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2025-10-19 01:29:01
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https://www.eevblog.com/forum/beginners/!help!-altuim-designer-pcb-layout/
|
!HELP! Altuim Designer PCB Layout - Page 1
|
[
{
"post_id": "",
"author": "YaSaRa_N",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 17, 2019, 04:12:23 am",
"content": "Hi!I am designing a Micro-mouse robot as a hobby project. I did the schematic using the EasyEDA online editor. that is because i can directly chose parts from LCSC.(I use LCSC because of the lowest shipping rates). however, after creating the schismatic using EasyEDA, I convert it to a PCB and then exported it as a Altium PCB ducument(.pcbdoc) to do the routing.Once I opened the file from Altium it works fine except for that there is a white box around each component. (as shown in the attached image. it only appears once i selected the component)it seems to be a clearance thing. as in the image 1 , I cannot move R48 or R50 closer to the SW5. when the components are in either horizontaly or verticly, this white box is basically the package outline and its ok.but when i rotate a component, it becomes bigger. How can i get rid of this ? i am using AD19.Thank uou."
},
{
"post_id": "",
"author": "YaSaRa_N",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 17, 2019, 06:02:24 am",
"content": "Quote from: blueskull on July 17, 2019, 04:14:43 amI disabled the component clearance rule but no luck.At the very beginning of the layout i was able to place the components such that the white box overlaps. but now i cannot.So it must be a setting that i changed ?"
},
{
"post_id": "",
"author": "YaSaRa_N",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 17, 2019, 04:11:18 pm",
"content": "Quote from: blueskull on July 17, 2019, 06:10:25 amI tried that. no luck.however I installed AD18 and it seems to be working fine. I think it might be a bug in AD19. anyway problem solved. Thanks for the replies.now i can place components anywhere i want. even on top of another"
},
{
"post_id": "",
"author": "Dave",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 18, 2019, 04:56:23 am",
"content": "If you want clearance rules to work correctly in Altium, you need to have 3D models embedded in the footprints. Otherwise it does what you've noticed: draw stupid rectangles around the footprint and claims everything is colliding. This often isn't a problem if all components are horizontal or vertical, but it's absolutely useless at any other rotation angle."
}
] |
2025-10-17T18:06:44.387219
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/!updated!-beginners-shopping-list!/
|
!UPDATED! Beginners Shopping list! - Page 1
|
[
{
"post_id": "",
"author": "Lisbeth",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 11, 2015, 01:45:04 am",
"content": "Hey everyone!Bout a couple weeks ago, I made a post here about my shopping list. I realized I wasn't getting as much bang for my buckby a nice friend of mine as he suggested I try SparkFun. I check it out, and dear lord in heaven, I get SO much more!First off, the soldering Iron. Geniuine Hakko, which is always a good sign. I also found the ever so elegant Chisel tip so that'staken care of as well. But I also found some alligator clip jumpers, a moderately good digital multimeter, a screwdriver kit with a large bit set,spools of differently colored hookup wire (solid core), a nice tool kit that comes with a bundle of tools and with a nice carrying case. ^^All in all for slightly under 200$! I also went and added a notebook and hackerspace passport, cuz why not? X3Here's the wishlist containing all the tools if you wanna check them out!https://www.sparkfun.com/wish_lists/111182I would love some more suggestions and tips! ^^"
},
{
"post_id": "",
"author": "GreyWoolfe",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 11, 2015, 02:07:54 am",
"content": "Better price for the Hakko here:http://www.all-spec.com/products/FX-888D.html?gclid=CjwKEAjwg7yqBRCu5NmlgMm6i08SJADDEudZ9Sf0YXucTKmGDJhhiXPX2ohhyQXCAk3Sv1rzSiYATxoCRvfw_wcBPlease don't try to measure anything but low voltage with that meter, it's too dangerous. I have 'precision' screwdrivers with bit sets and I like them but I also have numerous screwdrivers in different sizes/styles. You will find trying to fit the bit sets into tight spaces becomes difficult with the bulge on the shaft that holds the bits. It seems that the more individual screwdrivers I get, the less I use the sets. You might be better suited by buying screwdriver sets instead. It will cost more but hey, who doesn't want to have more toolsDon't forget solder/flux, isopropyl alcohol, flush cutters, dental probes, locking hemostats (probes and hemostats are plentiful and cheap at flea markets). A package of bamboo skewers also serves double duty as non conductive high tech pointy thingies for probing circuits and old toothbrushes are good for cleaning flux residue. A variable output power supply will also be useful. I'm sure others will add to this."
},
{
"post_id": "",
"author": "Lisbeth",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 11, 2015, 02:33:13 am",
"content": "Quote from: GreyWoolfe on May 11, 2015, 02:07:54 amWhy do I have to have such a small budget..."
},
{
"post_id": "",
"author": "xrunner",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 11, 2015, 02:40:42 am",
"content": "Quote from: Lisbeth on May 11, 2015, 01:45:04 amHow much more money canweyou spend?"
},
{
"post_id": "",
"author": "cellularmitosis",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 11, 2015, 03:33:25 am",
"content": "If you've got another $50, you should get a power supply.I've been happy with this one:http://www.ebay.com/itm/Bench-Power-Supply-0-2Amp-0-18VDC-Adjustable-DC-Regulated-CSI1802X-/221584095605?pt=LH_DefaultDomain_0&hash=item339770f975I'd suggest replacing the pots with 10-turn pots as your first hack on this piece of equipment.https://www.eevblog.com/forum/testgear/picked-up-a-csi1802x-bench-supply-%28$50-0-18v-0-2a%29/A good goal would be to try to limit yourself to only buying one (crappy) power supply ever. When you inevitably need second one, or one with better specs, design and build yourself! Building your own power supply seems to be like a Jedi making his own light saber: at some point every EE hobbyist must do this as a right of passage"
},
{
"post_id": "",
"author": "Johndi",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "May 11, 2015, 03:48:16 am",
"content": "I noticed that your flag states you're in the US. If that is the case, then I would look at Lowes, Home Depot, or your local hardware store for a precision screwdriver set. I have the HDX 23 piece precision screwdriver set pictured here and its done me well for things that I've needed to do for the price:http://www.homedepot.com/p/HDX-Precision-Screwdriver-Set-23-Piece-009-177-HDX/203436713"
},
{
"post_id": "",
"author": "Lisbeth",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 11, 2015, 05:33:32 am",
"content": "Quote from: Johndi on May 11, 2015, 03:48:16 amThe one I have in mind has a bit more than the one you suggest:4\" ABS Plastic Handle with Rubberized Grip5\" Flexible Extension Neck5\" Steel Extension BarTorx T4, T5, T7, T6, T8, T10, T15, T20Hex Socket 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4Tri-Wing 1.5, 2.0Triangle 2.0, 2.3Star 1.5, 2.0Center Dot 1.0PZ0, PZ1M 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5H 2.3Slotted 1.3, 1.5, 2.0, 2.5, 3.0, 4.0Phillips PH00, PH0, PH1, PH2"
},
{
"post_id": "",
"author": "Lisbeth",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 11, 2015, 05:38:22 am",
"content": "Quote from: cellularmitosis on May 11, 2015, 03:33:25 amI'm thinking about building my own, nothing too powerful, then I can move on to buy my own."
},
{
"post_id": "",
"author": "kizzap",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 11, 2015, 09:12:16 am",
"content": "Quote from: Lisbeth on May 11, 2015, 05:33:32 amBeing that you are just starting out, I would consider getting something like this:I got that set at an \"ag\" show (agriculture:- farming) here in Australia for less then $5. I would be sure that you would be able to find something similar where ever you are.Then, get a decentish driver/handle, and it should get you through most problems you will face. The only exception to those are for those nasty screws that are recessed deep, in which case you generally need a better set of screwdrivers, but when that comes up, you can buy them then.As for designing the PSU: Great idea! Just don't do what I did, and let feature creep set in. Also be aware that any store bought one will be generally cheaper then building your own, as they have the benefit of mass production behind them."
},
{
"post_id": "",
"author": "Lisbeth",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 11, 2015, 10:56:00 am",
"content": "One issue I have been noticing with this post and the one before is that people keep linking me All Spec.Now don't get me wrong, All Spec is a great distributor for engineers. But I'm a hobbyist, and even thoughtheir soldering iron is cheaper than the one on SparkFun, the shipping does not... It adds 6 dollars and some changeto the original price. While buying the iron from SparkFun, or anything above 75$ on the site comes with free shipping.So yeah, I think I will buy from All Spec WAAAY down the road if I get really into it, but for now, I'm satisfied with whatSparkFun provides.Also, as far as the multimeter, I would not trust it as far as I could throw it. But, everybody has to start somewhere andI DO NOT intend to be messing with wall socket voltage any time soon. Also, it beats having to pay 40$ for a multimeterthat can do the same thing, except with better design. Sometimes you have to compromise..."
},
{
"post_id": "",
"author": "nanofrog",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 11, 2015, 11:37:52 am",
"content": "Quote from: Lisbeth on May 11, 2015, 01:45:04 amAs per theHakko FX-888D, you might want to consider getting it from TEquipment.net instead (comes with a free cutter).Free shipping over $99, which you'll reach just by adding a couple of tips. They even offer it in kits (extras are usually popular styles of tips).They also offer a discount (code sent via PM), which usually makes them extremely competitive on price, if not the cheapest source.Other Tools:Screwdrivers- I'd recommend considering a dedicated set or two for slotted, Phillips, and Torx (ideally, security Torx <has a hole drilled in the end of the screwdriver>, as they'll work on either security or standard Torx screws). TheWiha 26190(basic slotted & Phillips set; also includes a free pair of needle nose pliers), andWera 2067/6(Wiha doesn't offer a set of this type). Use a bit set elsewhere, and upgrade as needed.There is also something similar to bit sets, but it's an entire shaft length, instead of 1\" bits (aka System 4 blade products from Wiha;example). Pricing can be very similar or more than dedicated drivers, depending on the set (blade system is more expensive than 1\" bit versions, but do keep in mind, there's usually a screwdriver profile ground into each end, so 2x per blade; exceptions would be nut drivers).Cutters & Pliers- Freebies included with the recommendations above (Wiha set + Hakko FX-888D Kit 2).Tool Roll you linked; skip it due to ^. Other tools you'll want can be had inexpensively from eBay, such as thevacuum desolder pump, and a pair or two of tweezers (say afine point tip&curved tip, Vetus brand).DMM-UT139C. It has a nice set of features and has decent protection for the price (you'd be able to use it with AC/mains).Quote from: GreyWoolfe on May 11, 2015, 02:07:54 am+1Much better to get the commonly used drivers as individuals to avoid this problem. There are times even standard shaft lengths won't reach the bottom of some recessed holes (i.e. need 4\" shaft length).Quote from: GreyWoolfe on May 11, 2015, 02:07:54 am+1 here as well.Make sure the consumables mentioned ^ are quality brands, NOT stuff made in China (solder & flux) . Look for brands such as Kester, Multicore (Henkel), AIM (American Iron & Metals), Indium, MG Chemicals, and Alpha (Cookson). All-spec is a good source for these. Granted, you'll have to pay shipping, but they're very fair with it (little to no markup from what they pay), and in the end, they're still excellent pricing to your door (particularly useful regarding solder & flux for example).Solder(note the diameter, as it's good for general purpose; flux type is RA <= Rosin, Activated>, and a flux core size of 66, which is 3.3% by weight). Lead based alloys are easier to use (only lead issue is if you handle it, then stick your fingers in your mouth or up your nose without washing your hands first).FluxThis is also a quality RA product, and more importantly, is available in hobbyist friendly sized containers. You can dispense it with a needle bottle, refillable felt or brush tip pen, or just use a hobby artist brush (usually located inexpensively on eBay and similar sites; some may be counterfeits, such as BON-102 refillable brush pens, but should do the job)."
},
{
"post_id": "",
"author": "Fat",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 11, 2015, 02:49:44 pm",
"content": "I have had bad luck with the Vetus tweezers (maybe it was just my set?), the tips were very soft and after a few days they didn't touch at the tip. Tried rebending, but not much luck. I tried the Hakko brand, and have had some very good luck with them. They are not much more than a pair of Vetus if you shop around.I have a background in watch making (previous hobby) and am kind of particular about my tweezers.Fat"
},
{
"post_id": "",
"author": "redshift",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "May 11, 2015, 04:36:15 pm",
"content": "Here is my advice:Hakko FX-888D + Chisel Tip- This makes up more than half of your budget but if you're comfortable with that, it's a great iron. Ordering from TEquipment instead, as nanofrog suggested, makes a lot of sense. You'll also need some solder(the little tube in the roll-up kit doesn't count) and good solder is expensive.Sparkfun Multimeter- It's hard to give any advice on this unless you're willing to buy a more expensive meter. But no auto-ranging, doesn't power down on it's own, etc. Also, generally cheap meters like this have pretty awful continuity testers, but this is just a hunch.Six 25' Spools of 22AWG Wire- This seems like a good price especially considering you get six colours and a box that dispenses them.Aligator Clip Leads- Good price but I'd think if I had to choose between the two, I would opt for female-male and female-female test leads instead.Roll-up Tool Bag Kit- Convenient. But I think that you could source the components more cheaply. Also, the look of the solder, wire-strippers, cross-lock tweezers, and screwdriver set don't impress me.Screwdriver Set- Cool.But one thing I'm wondering about this list: Is this just theequipmentyou're buying? Because you have no parts to play with. Sparkfun will have competitive prices on genuine Arduino's, etc if you want to throw some stuff like that in too. Their components are expensive though.Lastly, do you have a breadboard? Some sort of power supply? Small collection of passives? Because you should get all of those things tooYou might be interested in getting something likethisorthisso that you don't have to worry about resistor/capacitor values for a while.Maybe we can have a follow-up digikey cart when you have some new projects in mind"
}
] |
2025-10-17T19:40:54.611368
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/$120-$150-budget-build-to-learn-soldering-need-opinions-on-my-selected-parts/
|
$120-$150 Budget build to learn Soldering. Need opinions on my selected parts - Page 1
|
[
{
"post_id": "",
"author": "OntoTheWoods",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 28, 2024, 05:57:49 pm",
"content": "I would first like to preface this by saying that I do not live in the US, but rather in the Philippines. That's why some prices are cheaper, and some items like the Pinecil v2 are more expensive to procure.ModelProductPricePTS200 v2 AluminumSoldering Iron$21Aneng 683 TouchMultimeter$15Hayve 7\" HD 1200X 12MPDigital Microscope$39.5Yihua 8858-V (I don't think this is enough, more info below)Hot Air Station$19Yihua 948DQ-IFume Extractor$15Goot GS-104 MediumDesoldering Pump$14Anker Atom 2 60wIron Power Source0GRAND TOTAL123.5Soldering Iron - PTS200 v2 - $21I've searched reddit and found a couple commonly recommended Irons such as the:Pinecil v2 - $40.TS80P - $49HS02 - $31PTS200 v2 - $21 (just because the seller is doing a sale + coupons, original price is around $32)The Pinecil V2 and ts80p are one of the most commonly recommended budget Irons I've seen on that sub.However, I do think they're a bit outdated (but can be seen as a testament to their reliability) and based on the 2024 posts I've seen, the HS02 seems to be showing up quite a bit.But after digging deeper, I've seen the PTS200 v2 come up a few times, and just from a pure spec-wise comparison, The HS02 and PTS200 v2 seem to be the same in terms of build quality and having the ability to reach 100w.However, the similarities end there, the most glaring difference is their shape, and I find the PTS200's shape to be subjectively better. The PTS200 also use the ESP32, which theoretically could run IronOS, although official support for it is still currently unavailable. Although there's a custom firmware out for it, not that I know much about that, I just wanna plug my Iron and dissolve some solder. PTS200 can also accommodate t12,t13,ts tips.So there, that's how I decided on the PTS200 v2. I crossed out Pinecil/ts80p because they're twice the price, has less max power, and are less durable. I crossed out HS02 because if it's the same as the PTS200 in terms of build quality and 100w power, the next most important thing to consider would be the shape and then tip compatibility.Aneng 683 Touch - $15Any multimeter would've probably worked for my use-case. The design, recharge-ability, touch screen, manual mode (compared to the 681/682) and extra bells & whistles @ this price was just too attractive to pass up.Hayve 7\" HD 1200X 12MP - $39.5Seems like a decent plug-and-play solution at an attractive price.However, I'm a bit on the fence on this one as I have particular setup in mind wherein I could build a 4k streaming digital microscope. Would be a cool project to do once I get the hang of soldering.I could potentially can get a 4k Sony imx 678-based Microscope + Orange Pi + 4k capture card for around $110 and build my own 4k microscope set that can stream to my iPad Pro or 4k screen. Maybe add in another $15-20 for a built-in battery pack that I could read the power from as well and throw it to the feed for a truly wireless experience.Software-wise, it seems fairly easy to do in theory, but that's because I'm a programmer and already made much more complicated web apps. Just setup Nginx as your web server, install a video encoder, setup to encode the video sent by the capture card, encode to something like rtmp, have Nginx serve it using the device's local ip address (or your ddns of choice). Access web server from my iPad/Phone/PC. I just need to study the hardware side.I also own a 3d printer, so I can definitely create the perfect housing for this, maybe even include some fans.Yihua 8858-V - $19Looks like a decent hot air station for its price, and from a known brand at that. Can't really find another hot air station around this price. Currently getting the version 5, which was probably released around 2022-2023. The only gripe I found online with this one is that some people have a hard time triggering the auto shut off due to the angle the holder has. I could very easily design and 3d print a better-angled holder to alleviate that problem. Or if the filament can't handle the temps, just make an angled base to rest the device, so it leans more and easily activate the auto shut off.HOWEVER, I received a reply from someone who actually ones the 8858 (but maybe not the exact V version) that claimed that this was simply underpowered air volume-wise and burnt their board.So I may have a bit of leeway on the budget for this one as I can see myself using this tool equally as the iron.So far, here are the new models I picked out:RF4-H5 = $75. Got the idea from this post:https://www.eevblog.com/forum/reviews/rf4-1000w-hot-air-rework-station-rf-h2-$125/Forward FW-HA01 = $66. It looks like it's based off of the H5 (or is it the other way around? Both were released around 2-4 months ago). It's not a 100% rebrand, but the knobs, number of memory buttons, heck even the pump looks very familiar to each other. And what even confirms my suspicions is that they almost have the same specs. Both can do 800w, 50L/Min Airflow, brushless turbine fan, 13000r/Min fan speed, 80cm handle. The only difference they have in their specs is that the H5 can do up to 480C, whereas the Forward can do up to 500C. And the H5 uses a Nixie display and the Forward uses a segment display (which I admit to be unfamiliar with, so I asked Claude and it said that the segment is much more durable). Haven't really seen this brand recommended, but they seem to be focused on mobile repair, and have a couple high end products as well. Their website also looks clean and professional (to be fair, as a web dev, you could easily spin up a site like this in less than a week, but I appreciate that they took the time to design it well, use https, and even purchased a .com domain).RF4-H6 = $45Yihua 959D II = $40Yihua 858D = $23Yihua 948DQ-I - $15Nothing much to say. A cheap and decent fume extractor from a known brand. I guess this is better than nothing. I have a 650cfm Dewalt fan (would most definitely not max it though) that I'll angle a bit toward it to help with the air flow and blast any remaining fumes. There's the II and III versions, but they all use the same extractor, the difference is that the latter ones have extra stuff that I already have.Goot GS-104 Medium - $14I was leaning on the SS-02 but found a forum reply @https://www.eevblog.com/forum/reviews/engineer-ss-02-solder-sucker-or-other-nice-desoldering-pumps/of someone who has the SS-02 and Goot pump, and he seemed to lean more towards the Goot.Anker Atom 2 60wI was gonna buy a 100w power bank, but since I only wanna work on pcbs, I decided to just use my existing charger, seeing that pcb work is mostly <=60w.Final thoughtsAs for the flux/solder/attachments for holding the items, I opted not to include them since they're fairly cheap enough to experiment with. Also, some of the brands suggested in this sub aren't available in my country. My plan is to just get the smallest rolls from a couple of brands and practice with them on a test board to see which one is more effective.I really only wanna learn soldering, this wouldn't be used in any commercial capacity, I'm looking at 10-15 hours a week of usage. I'll be happy if this set lasts me 2 years. I think that's enough time to determine if I wanna go ahead and splurge on the big guns. I've already learnt my lesson in spending too much for things that I quickly lost interest in such as power tools, gym equipment (to be fair I still use some), airsoft, drones, cameras, etc."
},
{
"post_id": "",
"author": "K5_489",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 05, 2024, 06:15:52 am",
"content": "It might just be the old fart in me, but I just don't understand the draw to all these \"smart\" irons, especially so when I see reports of people frying them left and right just from using the wrong USB power supply on them. And then a need to be constantly updating them...how many firmware updates does it take to heat up a stick of steel to a set temp?Reliability you say? I've been using the same Hakko 936 soldering station for almost 20 years now...and for the few times I needed to take a soldering iron to the work instead of the bringing the soldering work to the bench, a Weller butane iron...also for about 20 years.I suppose an argument could be made for a need where 99% of your soldering had to be done off bench...Or if canned butane is a pain to obtain wherever you are.Something I've seen reported time and time again on a lot of these \"off brand\" irons are the tips are absolute garbage, but seem to work well once replaced with genuine Hakko tips, when the irons are built to use Hakko style tips, of course. Which would be one of my big recommendations - get something that uses Hakko style tips. Eventually you're going to want something other than a basic point or chisel tip, and there's a bunch of different sizes & shapes in the Hakko line. Geniune Hakkos are so cheap that there's really no reason to run the clone garbage.I feel genuine Hakko is worth the money, and my first inclination is skip all the extras, get yourself a Hakko soldering station, andhave fun. But I understand budget is budget, and my next thought is to get something like a Yihua 936 or 939. Save a few bucks, roll it towards your next gear buy once you decide yay or nay on this.Fume extractor - you want something that sucks the fumes away, not blowing across your work, especially if you're dealing with SMDs. I know it seems like semantics, but it's important. You also don't need super high airflow for this. All you're after is getting the soldering fumes directed away from your nose so you're not directly inhaling them. Honestly, I don't even bother for most of my work when it's just a quick resistor or cap changeout, and have done tons of work with nothing more than a simple computer case style pancake fan set on edge on my bench.Skip the hot air station for now. There's definitely an art to using one effectively, getting it wrong can quickly destroy a PCB, and you're probably not going to use it much while learning the simple stuff first anyways. This is one of the things you really don't want to cheap out on. You really want something that can blow of LOT of really hot air quickly, so you can get in and melt the solder fast and get back out without heat soaking the parts. Until you get a feel what it takes to melt and flow solder quickly, you're just going to break things with a hot air station to the point of not being able to repair them, and just do it faster with a cheap hot air station.Same with the microscope. You're going to need a good feel for this to begin with, and that's going to be amplified 10 fold when you're dealing with parts tiny enough to need a microscope. Jump right in to that on day 2, and you're likely to just get frustrated enough to want to bin it all and move on to the next hobby."
},
{
"post_id": "",
"author": "JustMeHere",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 05, 2024, 07:00:35 am",
"content": "Get a real soldering iron. You'll end up spending the same once you factor in a power supply and a cable. You really want silicone cables hooked up to the iron.Spend $75 or more on the iron. Don't worry much about anything else until you learn how to solder. And you don't need much more than an iron, a multimeter, and an inspection loupe for that."
},
{
"post_id": "",
"author": "Solder_Junkie",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 05, 2024, 07:46:57 am",
"content": "Stick with a proper soldering station, Hakko or Weller. Use only genuine tips and branded solder.A digital camera is hopeless for SMD soldering, you need stereo vision from a binocular microscope. The Swift type with two LED lights is pretty good. Also needed is a low profile PCB holder for SMD work on small boards, such as those used to repair mobile phones.This video shows you all you need to know about hand soldering both through hole and SMD parts.https://youtu.be/eZtPR8_x0nc?feature=sharedSJ"
},
{
"post_id": "",
"author": "SteveThackery",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 05, 2024, 08:09:26 am",
"content": "About the microscope. There are two things I can share my experience with. Firstly, make sure the microscope provides enough working space under it. Secondly, lag. One of the mics I bought had a nasty delay in the video feed to the monitor, making it very difficult to work with it. Fine movements are very difficult to control with a delay in your visual feedback loop.Also, there's the problem of 3D. A simple mic plus screen gives you a detailed picture of the work, but with no depth information. Makes you clumsy. That's why I no longer solder like that. For most work I use a good quality \"visor\" with optical glass lenses, and if you haven't used one before it's a transformative experience. Importantly you see in 3D. For the really small stuff I use an optical binocular microscope. Again, you see in 3D, and again it's a transformative experience."
},
{
"post_id": "",
"author": "nmcgann",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "October 05, 2024, 10:33:00 am",
"content": "Quote from: Solder_Junkie on October 05, 2024, 07:46:57 amThat is a good video. I’d also recommend the “Mr Solderfix” channel, there are some great SMT soldering videos on there. I followed his advice and got some 0.25mm solder (lead free) for doing SMT work and that has massively improved the joint quality and consistency I can achieve.I second the good iron+tip+solder advice - I have a Weller TCP station that is 40 years old and a Hakko FX888D that I got recently, both are very good."
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2024, 02:34:14 am",
"content": "LOL! The OP has a budget under $150 and everyone is recommending he spend 5 times that. Folks, not everyone can afford the best equipment in the world .. and they don't need to. I have an old Hakko 936 station and I have an even older Weler. Guess what I use 90% of the time? A FNIRSI HS-01. Yup, a $30 iron. Why? because it heats up faster, maintains temperature better, is smaller and lighter and is cheaper to run. So, it might be easy to brush me off as a know nothing newbie, but no, I've been soldering since I was 10 years old. That's 57 years of experience including at least 10 years doing it as a part of my profession from production line, through production re-work and on to CET.Even a cheap Hakko FX88DX or an equally cheap Weler WE101NA will blow his entire budget, yet they are not great performers compared to something like the $30 HS-01. I know from actual, real experience. Yes, having actually used all of these. To get the performance of something like the HS-01 from a Hakko where the heater and sensor are built right into the tip, and it will heat up from cold in 8 seconds, and from standby in 3 seconds and will shut itself off it you forget for safety and to prolong tip life, you'll need to spend a lot of money. Alotof money. Yes, it will last longer and will perform better, but replacement tips for it cost more than the whole HS-01! And .. he does not have $900 to spend on an iron.My grandfather used to use a soldering iron he heated up in a bed of coals. He swore by it. Made his living with it. No one uses those anymore. Don't knock these little smart irons until you have put them to use for a few hours. They work, and they work well.Let's not get into $900 binocular microscopes!To the OP, your list looks good. It will do what you want and if one of those items is not putting a smile on your face, there are other options you have for replacement when funds permit. Please don't get discouraged by the equipment snobs. The most important thing is for you to get started and your list will get you going. Once on your way you can decide if you enjoy electronics enough to continue and upgrade your equipment or not. I think you are taking the right approach. The only thing I don't think you need to get started is that digital microscope. I can't imagine it would be a great performer. A good magnifying glass you can mount on a retort stand would probably be a better choice for about the same money. Just my opinion and I could be wrong on that as I don't have any experience with that particular DM, but I've had access to similar items that left a lot to be desired."
},
{
"post_id": "",
"author": "shabaz",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 06, 2024, 03:05:21 am",
"content": "Quote from: BillyO on October 06, 2024, 02:34:14 amUnless some messages are deleted and missing, I don't see that at all. Everyone above appears to have offered suggestions that are well within the budget."
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2024, 03:14:20 am",
"content": "Quote from: shabaz on October 06, 2024, 03:05:21 amOh, really? My mistake.Since you are so sure, please give the model numbers of a Hakko soldering station and a binocular microscope where you can get both for under $150.The absolute cheapest iron you can get from Hakko is $100 and it is and absolute POS. So, now you have to get everything else, including the suggested binocular microscope, for $50. I'll stand by for your revalating response in great anticipation .."
},
{
"post_id": "",
"author": "shabaz",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 06, 2024, 04:49:09 am",
"content": "One person who suggested a Hakko station advised not to get a microscope for now. Another person explained that a digital camera would be a disappointment and suggested a microscope. I don't think they suggested that the OP should now hold off and not buy a soldering iron until they had saved up a thousand $. They reiterated that a proper soldering station is advised. That's very good advice. Yet another person again advised against a digital microscope, and made the suggestion of a head-mount magnifier. They are excellent.Anway, if someone really did want a binocular microscope immediately, what's wrong with Craigslist/Gumtree type websites? That's precisely how I got my binocular microscope, so it's possible. Even new microscopes do not have to cost a lot; but personally if you ask me (well, even if you don't), I'd advise a second-hand binocular microscope at that sort of a budget. That's if they really need it. A head-magnifier works great and is low-cost; worth the OP considering that (and the good advice that was given) if they have not already done so.You certainly can buy cheap brand new binocular microscopes at low-cost. Is it advised for a beginner? Certainly not, so why even raise a challenge of fitting a $125 budget on that, plus a soldering station?What's with the dumb popcorn and fizzy drink emoticon? It's childish, grow up. You're just being argumentative and that's of no benefit to anyone, especially not the OP."
},
{
"post_id": "",
"author": "JustMeHere",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 06, 2024, 08:27:53 am",
"content": "Quote from: BillyO on October 06, 2024, 03:14:20 amNot sure why you're copping an attitude. No need here for that.Basically there's no point in buying too many things until the first skill is learned: how to solder.If cheap tools are purchased so \"all\" of the tools are purchased, then the effort becomes self-defeating.Step 1: Get a decent soldering iron and learn how to use it.Don't skip to needing to do anything that requires a microscope until step 1 is accomplished. No need having a microscope until you can do step 1 well. If having the microscope causes step 1 to never be accomplished well, then the microscope should not be bought at the beginner step.Basic project management: when resources are limited, focus on the critical path. Don't spend resources on anything but the critical path. If you spend resources on other things you may never need the other things because you never got past step 1. Microscopes are nice, but you don't really need one. A $10 hand loupe works just fine. The loupe is for inspection. (https://www.walmart.com/ip/Carson-Minibrite-3x-Pocket-Acrylic-Lens-Magnifier-with-Built-in-LED-Light-and-Sliding-Case-Gray-PO-25/11186221?wl13=1383&selectedSellerId=0&wmlspartner=wlpa).Now when you move past the beginner stage and do so much work the loupe is slowing you down then you can consider the microscope. Hopefully at this time you have acquired more resources."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2024, 09:04:11 am",
"content": "A combo hot air and soldering iron station (e.g. YIHUA 8786D) is worth considering - not instead of a soldering iron that takes cartridge tips (integrated heater), but in addition to. Hakko 900 style tips are dirt cheap and if they are a decent fit to the element (shim if necessary), the 907 style iron is more than adequate for less demanding soldering tasks + you have less clutter on the bench. Because the tips are cheap you can afford a wider selection. When you encounter a difficult joint, or are out in the field, grab the PTS200 or similar cartridge iron.Also its always good to have min. two irons otherwise what do you do when your one and only iron goes wrong and you need to fix it?"
},
{
"post_id": "",
"author": "xvr",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 06, 2024, 01:58:56 pm",
"content": "QuoteExactly! I've got my first iron at age 10 (take or give), and microscope at age 40. And I still don't need fume extractor (at age 57). Do not hurry."
},
{
"post_id": "",
"author": "K5_489",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 07, 2024, 12:22:44 am",
"content": "Quote from: BillyO on October 06, 2024, 02:34:14 amGenuinely curious....how is $60 five times as much as $150? The math doesn't seem to track here, but I'm always open to new ideas..."
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 07, 2024, 12:32:56 am",
"content": "Quote from: K5_489 on October 07, 2024, 12:22:44 amWhat is $60? A Hakko soldering station plus binocular microscope (and no, just no, on that plastic thing from the sex toy shop)?"
},
{
"post_id": "",
"author": "Andree Henkel",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 07, 2024, 11:27:39 am",
"content": "Things you should start with, and which you should notSoldering Iron:YesHot Air Station:No, something for laterMultimeter:Yes, you will need the continous check mode with beep, you need sharp and small tips at your probesdon´t buy DMM with fixed attached probe cable, but with banana Jacks and included probe cables.fast beep is important. the beep beep thing is just the one thing this \"meter\" needs to do really nice.sice of display and backlighting is not that important for your app, as well as meas modes, digits and accuracy,but: Auto power off is must have, if possible with way to disable, you will curse every timeyou forgot to turn off and battery is emptyMicroscope:No, something for laterMore important is a good light: LED Ring light with *3 magnification, lights your workspace, and for smaller components you look through italso a magnifying glass *7, much cheaper than µsope, you need the money for the ringlightfirst is much more essential than µscope, second will postpone need for µscopeSoldering pump:No, I solder almost every day, and never more need feel need for one, I have sure used them. Only useful if you do a lot of through hole desolderinginstead get a good solder wick, which is essential for SMD, but handles through hole as well:https://www.reichelt.de/de/en/desoldering-wick-1-5-m-1-5-mm-edsyn-sw021-15-p247901.html?r=1this is best I ever used, It is tinned+flux , which greatly improves capillary action compared to just copper+fluxSolder: don´t underestimate Importance, don´t buy just cheapest alloy, more expensive ones are especially great for learning soldering, as the appearance of joints is better, so you can learn to evaluate the quality of your solder joints better.First you have to decide unleaded or leaded.I use leaded, to avoid damaging prototypes (like torn pads) by the higher melting temp of unleaded solder.Best leaded solder I use: 0,5mm Diameter, ofcourse flux, eutectic Sn62Pb36Ag2, the 2% silver make a differenceOther stuff needed right at start:*soldererin iron stand - if not included with iron or station*sponge for tip cleaning or wool for this purpose, if not included with Iron / stand*soldering tip tinner*pair of tweezers for holding small components*in case you want to deal with wires:#side cutter#wire stripper"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 07, 2024, 12:22:24 pm",
"content": "Hot air is increasingly necessary to even work with modern parts. You'll curse any attempts at reworking any SMD IC if you don't have it, and good luck soldering a QFN IC without it - the center pad is essentially unreachable by soldering iron unless its your own board and you design it with one or more large through-plated access holes in the pad, which makes it unsuitable for standard SMD assembly processes. If you aren't interested in component level stuff and only need to solder wires and headers to pre-assembled modules you can do without.Desoldering pump (aka:Solder sucker): *YES* - its good for bulk solder removal not SMD stuff but when you need one the alternative would be to use up desolder braid by the meter! However *DON'T* buy an expensive one. The cheap blue plastic aluminium barrel ones with the machined shaft are entirely adequate for a beginner, provided their plunger O ring is kept lubricated with light silicone oil or silicone spray lube, and only cost a few dollars. DON'T buy one with a pressed U section shaft - they are absolute cr@p - See:https://www.eevblog.com/forum/reviews/need-a-new-solder-sucker-suggestions/The visible difference when buying is a machined step and taper groove right round the shaft up near the plunger cap - if its got it its OK if not its junk!"
},
{
"post_id": "",
"author": "Andree Henkel",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 07, 2024, 01:09:07 pm",
"content": "regarding Hot air: you are surely right.But he is short on budget.So I suggest to skip hot air and µScope FOR NOW and spend the money on ringlight, accessoires and better tool quality."
},
{
"post_id": "",
"author": "K5_489",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 07, 2024, 07:50:17 pm",
"content": "Quote from: BillyO on October 07, 2024, 12:32:56 amQuote from: K5_489 on October 05, 2024, 06:15:52 amhttps://www.amazon.com/YIHUA-Professional-Digital-Soldering-Station/dp/B07RVMZNYR/Yihua 939D+, currently $53.99.Later on in that same post of mine, right after telling OP to skip the hot air station for now -Quote from: K5_489 on October 05, 2024, 06:15:52 amAgain I ask - how is $60 five times as much as $150?"
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 07, 2024, 09:26:05 pm",
"content": "Quote from: K5_489 on October 07, 2024, 07:50:17 pmQuit trolling!Quote from: K5_489 on October 05, 2024, 06:15:52 amThis tells me you have no first hand information to share. You also first suggested a Hakko station - minimum ~$150, and it's no great shakes.Someone else suggests a stereoscopic optical microscope - Let's suppose you can get one that has real glass in it's optics used for t$150. I seriously doubt it though. Someone else suggest only use top name-brand solder - There's $65 for a 1lb spool of Kester or the like. Someone else suggests a better DMM, so throw in another $60. What are we at now? $425? Beginning to look like 3x the budget of $125-$150 to me.A single Hakko station that's worth its salt is 5x just by itself.I didn't call any one person out, so why are you trolling me?Just more elitist BS"
},
{
"post_id": "",
"author": "Old Printer",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 08, 2024, 12:14:33 am",
"content": "Five years or so ago I bought a Hakko FX888D as my first \"solder station\" and I like it very much. Head and shoulders above the standard irons I have used for years. I am sure Weller sells an equivalent. I paid $100 and they are $120 now. I moved up to a FX951 just because I got a good deal on a nice used one. I would recommend something in the class of the FX888, a good quality magnifying visor and a bright flexible work light. I would also skip the lead free stuff, unless you have a very good need for it. Regular solder will be easier for a beginner to work with, the lead free can come later, if at all. Be careful of counterfeits for the Hakko stuff, buy from a known dealer."
},
{
"post_id": "",
"author": "J-R",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 08, 2024, 06:49:30 am",
"content": "Another drive-by post. Will the OP ever return to observe the aftermath??There's no denying that if you just want to get some gear to play with on a tight budget, the cheap stuff will get you started. And I think that was made very clear by the OP.Side note, Hakko recently released the updated FX-888DX and the current sale price here in the US is $97.17 with free shipping and gifts:https://hakkousa.com/breast-cancer-awareness-2024-promo1"
},
{
"post_id": "",
"author": "K5_489",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 08, 2024, 08:34:38 am",
"content": "Quote from: BillyO on October 07, 2024, 09:26:05 pmNo, you didn't call any ONE person out. You quite literally called EVERYONE out, and now are shockingly digging your heels in deep on showing how wrong you can beNow excuse me while I throw away all my perfectly functioning gear to try out some cheap stuff that dozens of people have reported is garbage, just so I too will have \"first hand experience\" to report that it is in fact...garbage.I'd wonder how people like manage to survive on a day to day basis, but there's not enough psychedelics in the world to make it make sense..."
},
{
"post_id": "",
"author": "Aldo22",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 08, 2024, 03:21:02 pm",
"content": "Quote from: K5_489 on October 05, 2024, 06:15:52 amThanks for the tip!I had never thought of that before.But I solder too rarely to need an extra device for that.I just tried the handheld vacuum cleaner that I already have.It works perfectly!Absolutely no more fume in my nose."
},
{
"post_id": "",
"author": "K5_489",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 08, 2024, 06:51:33 pm",
"content": "Quote from: Aldo22 on October 08, 2024, 03:21:02 pmGlad someone found my ramblings useful other than displaying how they can't do math...or read...lolI've done the same thing with a Datavac, with a window exit hole panel I fabricated. The small hose size made it relatively easy to use on the bench without relying solely on the filters to clean the exit air, but I figured if I mentioned that, someone would lose their mind over my \"suggestion\" to use a $500 vacuum for a fume extractor. Little did I know..."
}
] |
2025-10-17T16:29:23.149606
| 25
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/$200-oscilliscope-any-recommendations-please/
|
$200 Oscilliscope, Any recommendations please? - Page 1
|
[
{
"post_id": "",
"author": "Azhar",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 30, 2016, 02:44:03 am",
"content": "I need to buy an Oscilloscope, my budget is $200, are there any scopes that you recommend?I need a simple 2 channel scope that do the basic stuff.thanks"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2016, 03:43:33 am",
"content": "This is the cheapest in the Siglent range if you can stretch to a new DSO for a little more than your budget.http://www.siglentamerica.com/pdxx.aspx?id=26&T=2&tid=1You can get a EEVblog members discount to buy from Saelig.Ask for the discount code in this thread:https://www.eevblog.com/forum/testgear/equipment-discounts-from-saelig/"
},
{
"post_id": "",
"author": "Muttley Snickers",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 30, 2016, 04:31:13 am",
"content": "The price of $239 on the Siglent seems like a fair deal providing you live in the US, not quite the same ballpark if you need to buy it locally down here though.Trio Test/ Siglent.http://www.triotest.com.au/shop/siglent/2948-siglent-sds1052dl-50mhz-2-channel-widescreen-oscilloscope.htmlUnfortunately as far as a new scope goes you probably wont get much more than a toy down here for $200, some of the Hanteks, Attens/ Grattens go for a little over $300 on Ebay but be careful where you buy one because if found to be faulty or dead on arrival then you might have to pay the postage back overseas just to claim a refund, Paypal required me to send a small item back to Asia using the most expensive postage method they could dream up yet it arrived via the cheapest method possible from interstate.As an example these types of listings below deserve special attention and can be a serious trap for the uninitiated, the items location states Riverwood, NSW, Australia but if the parent Ebay account holder is located elsewhere then that's where the item needs to be returned according to Paypal, this happened in my case with a Hobby King deception so always verify where the item is truly located, where it is to be returned to and any other terms involved even if shipped from what may appear to be a local region."
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2016, 10:28:25 am",
"content": "One way to consider is older Tek 7000 series. You start by getting themainframe + amp + timebase plugins.The advantage is the broad selection of plugins you can buy as necessary,like high gain diff amp, counter, digitizer, spectrum, sampling....very flexible.This approach does not have the sophisticated math and trigger system of a modernscope, but when used in conjunction with a modern scope very useful.http://w140.com/tekwiki/wiki/Main_PageRegards, Dana."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2016, 08:26:50 am",
"content": "If your budget is $200,the best general purpose unit you will get will be a secondhand analog 'scope.The US$400 DSOs often mentioned in this forum get a lot closer to $A700 when you take exchange rates,freight & so on into account.The days of the \"mighty Oz\" being at,& above parity with the greenback are long gone!Unfortunately many eBay sellers,seeing this increase in cost for new DSOs, have also increased their prices for old 'scopes to quite absurd levels.There are still some Oscilloscopes on eBay for sensible prices,though,& there are other sources.Look for Hamfests in your area----they often have a good selection of older test equipment,but sometimes don't.The advantage of Hamfests & other such \"swapmeet\" style meetings is that you can ask to see the device operating.Don't blow all the $200 if you possibly can find a ;scope at around $150 or under."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2016, 09:15:25 am",
"content": "Quote from: vk6zgo on October 01, 2016, 08:26:50 amMake sure it is aworkingscope. Ignore any ebay or other adverts that don't show awaveformoneverychannel. My rule of thumb, here, is £1/MHz for a low end scope.For debugging poorly controlled digital signals, 100MHz and higher is preferable. A 20MHz scope can be used for simple well-behaved digital signals (i.e. no signal integrity problems), and for mechatronics.Don't forget that probes are an integral part of makingeverymeasurement. Even cheap/grotty probes will cost as much as a low-end scope."
},
{
"post_id": "",
"author": "CraigHB",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 01, 2016, 03:15:09 pm",
"content": "Yes $200 is a bit on the low side. You'd have to go with something used. I have a Rigol DSO which cost around 400 USD new. I'm pretty happy with it, though I would like to buy a new once since mine is older and the newer ones have bigger displays. Probably just get another one in the same price range.An analog scope can do most of what you need, but there are some things an analog scope can't do a DSO is really handy for. I actually had an analog scope for the longest time until I finally got the scope I have now. Though now that I've been using it a few years I wouldn't want to go back to analog. A DSO's ability to store waveforms is actually a big help."
},
{
"post_id": "",
"author": "Azhar",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 02, 2017, 12:44:18 am",
"content": "thanks guys, that was helpful"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2017, 12:58:06 am",
"content": "What kind of stuff do you want to do with it? Do you need a DSO or would an analog scope work for you? It's hard to go wrong with Tektronix, one of my favorite scopes is the 465B, it's old now but still a very capable instrument and a nice one should be able to be had for $200 or less. Ideally look for one that includes a couple of probes, those can be expensive."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2017, 01:17:40 am",
"content": "I don't know anything about the used equipment market in Australia but here in the US, I bought a used 350 MHz Tek 485 for just $200 about 13 years ago.In looking at eBay today, the prices are around the same with a few very overpriced exceptions. I don't know enough scopes to recommend any particular model but you can search eBay for '100 MHz Oscilloscope' and find MANY scopes including some from GW Instek. But that's over here..."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 02, 2017, 04:38:49 am",
"content": "Quote from: rstofer on March 02, 2017, 01:17:40 amThe Australian market is nowhere near that.The population comparison between the USA and Australia is around 15:1 - and the used equipment market would be at least that squared, IMO. Add to that the premium we pay for being where we are and the chances for good deals on good equipment are vary rare.I'm sure anybody from Australia visiting the USA that is shown the best places to look, would want a small container to bring back the gear they would like to grab."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 02, 2017, 04:48:29 am",
"content": "Quote from: Muttley Snickers on September 30, 2016, 04:31:13 amI know it's an older post - and I don't know when you had to do the return - but did you know of this?...https://www.paypal.com/webapps/mpp/returnsIt was introduced as a trial mid 2015 IIRC and was made permanent later that same year.Seems it's still active."
},
{
"post_id": "",
"author": "lordvader88",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 02, 2017, 11:44:10 am",
"content": "If you are lucky, u can get a decent 1980-2000 era 1, working in good shape from ebay for >200.I sort of did, for 200 CAD, at the time maybe 170USDWithout having read the above, I say hold and save your money. Then buy a 500-1200 scopeI would like a? can't remember, but it will cost me +1200, perhaps this summer."
},
{
"post_id": "",
"author": "lordvader88",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 02, 2017, 12:00:26 pm",
"content": "hEY ALSO FOR $18usd, i JUST ORDERED A DSO138 oscilloscope, from ebay.It's a MINI / POCKET OSCILLOSCOPE, so will go very nice next to my DMMs. So it will very nicely provide a VISUALIZATION of stuff under 200kHz(and really less but thats fine)My 2nd hand, ch1 broken, $200 scope still lays in piecesI worry because I never labeled all the screws, so I have a few I'm not sure where they will go"
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 02, 2017, 12:44:04 pm",
"content": "Quote from: lordvader88 on March 02, 2017, 12:00:26 pmI got a kit version of that and made it up. It works - but don't expect too much from it and you might be OK with it."
},
{
"post_id": "",
"author": "daybyter",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 02, 2017, 01:26:52 pm",
"content": "http://www.stm32duino.com/viewtopic.php?t=107"
}
] |
2025-10-17T19:02:02.998433
| 16
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/$200-power-supply-new-korad-or-used-hp-tektronix-or-similar/
|
$200 power supply: New KORAD or used HP, Tektronix, or similar? - Page 1
|
[
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 07, 2024, 08:59:10 am",
"content": "Hello. I trust your experience more than my research. I’m going to spend in the neighborhood of $200 on a power supply. I need/want dual output, up to 30v, not sure about amps. I don’t mind servicing older stuff and actually like vintage stuff that is reliable but need it to work from the start as my project has a timeline. Based on past experience would you buy two KORAD KA3005’s (or comparable) or would you purchase a used, dual output HP, Tektronix, BK or similar off of eBay. I’m new with limited knowledge so if you have other suggestions please feel free to share other possibilities. Any help is appreciated."
},
{
"post_id": "",
"author": "aliarifat794",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 07, 2024, 02:52:57 pm",
"content": "These brands have a reputation for reliability and performance.Look for models that meet your voltage and current requirements."
},
{
"post_id": "",
"author": "donlisms",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 07, 2024, 03:06:24 pm",
"content": "I have bought several used Power Designs, one HP, and one Lambda supply, and had pretty good luck with all of them.The HP needed the most attention - the power switch crumbled; the smoke came when I turned it OFF! Confusing. Not a typical fail, I think. It also has old stiff wiring that needs replacing.The PD's just seem to work; I love them, and would like more, just because I like 'em, not because I need 'em!"
},
{
"post_id": "",
"author": "coromonadalix",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 07, 2024, 03:08:23 pm",
"content": "I'm not impressed by Korad .... i would choose any reputable brand well before that one, and if you don't find a dual one, buy two identical models,if it's the case you'll have to fiddle, serial and parallel mode ..Some Mastech and clones had better reliability in the pastDo note, you pay cheap, you'll get cheap"
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 08, 2024, 08:22:09 am",
"content": "Quote from: coromonadalix on April 07, 2024, 03:08:23 pmWhat problems did you have with your Korad?"
},
{
"post_id": "",
"author": "voltsandjolts",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 08, 2024, 08:31:08 am",
"content": "Buy your test equipment second hand, preferably broken (and repairable).You'll lose much less money that way, learn something doing repairs and likely make a small profit when you sell it on."
},
{
"post_id": "",
"author": "psysc0rpi0n",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 08, 2024, 09:01:52 am",
"content": "I have 2 Korad KA3005P. For what I do I cannot complain.From what I could check when I purchased them, they are accurate and the only thing that is on the cons is the confusing OCP and OVP buttons and their functions. I recently watched a video of someone trying to figure out how to deal with these 2 buttons and the guy was also quite confused!From minute 18, it starts the struggle with these functions! Other than that, I'm happey with both of them!"
},
{
"post_id": "",
"author": "BILLPOD",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 08, 2024, 12:39:50 pm",
"content": "Quote from: psysc0rpi0n on April 08, 2024, 09:01:52 am"
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 09, 2024, 05:26:30 am",
"content": "Quote from: donlisms on April 07, 2024, 03:06:24 pmWhat PD models would you recommend for dual output and up to 30V? Also, is Power Designs and Power Designs Precision considered the same quality?"
},
{
"post_id": "",
"author": "donlisms",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 09, 2024, 10:07:35 am",
"content": "There are several dual and triple versions, e.g. the TW4005 is a twin 40 volt 0.5 amp model. I don't have one but want one. I have a 6050, single output 60 volts or 5 amps, but not both at the same time!The Precision models, always with those nice four-digit dials, are probably about an order of magnitude more precise. Single output. Specs are 100uV noise and regulation and such; I usually see around 10uV or less, including watching the oven heater switch on and off. (Newer models used LM399.)The precision models are good enough that you start expecting them to be a reference; not to metrology standards, but sub-millivolt easily.Quality... well, I guess... the designs came out of the same brain, but for different purposes. They're all nice.All the PD's are old, no doubt. A little control cleaning might be in order; I keep thinking I should do that someday. Mine just work, except some of the meters. Which I should fix someday, but... no big deal.I should say this: the current limiting adjustment is intended as a safety net, not as a CC supply. The limit is a little vague. In those days, CC wasn't such a normal thing. As best I understand it, you want an infinitely high output impedance for CC and zero for CV, so supplies that try to do both must compromise a little somehow in their output circuitry.I suspect the HP's are similar to the PD's in most ways, including their precision versions (uhm... 6111? 6112? Others?)."
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 09, 2024, 12:37:33 pm",
"content": "Quote from: donlisms on April 09, 2024, 10:07:35 amThank you! This is helpful. They've come up in my searches. I like the old school look and assumed (but didn't know) the build quality matched the appearance. I'll include them in my list of options. Gonna have to pull the trigger within the next week or so. I appreciate your input."
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 09, 2024, 12:48:35 pm",
"content": "Quote from: MaxBishop on April 07, 2024, 08:59:10 amHave you built or repaired power supplies?What other test equipment do you have?What is your project and timeline?"
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 10, 2024, 05:38:31 am",
"content": "Quote from: Electro Fan on April 09, 2024, 12:48:35 pmI haven't built any but I'm gathering parts. I have a few laptop battery packs. I'm intimidated by the thought of it. Is there a build you would recommend? This is all new to me. I don't have anyrealgearother than a couple of voltmeters and an old, currently misplaced oscilloscope that my dad used to use many years ago. My project is already late, lol. I sent a message to an eBay seller tonight on an HP 3620. We'll see what comes of it. If that doesn't pan out there are a few other brands/models I'm watching"
},
{
"post_id": "",
"author": "Wallace Gasiewicz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 10, 2024, 12:05:35 pm",
"content": "About old PS, some of them have an IC that is very hard to find. This chip is the thing that blows, without the chip it is very hard to fix. I have a Lambda like this, I redesigned the control circuits for it but this is a hard thing to do. This is an old Lab Grade Supply with analog meters.I do not know if any of the more modern PS with Digital Meters have this same problem with hard to find reference chips.This is too bad because these old PS have good transformers."
},
{
"post_id": "",
"author": "mr ed",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 10, 2024, 09:25:03 pm",
"content": "I got fed up with cheap chinese switchers and went with used hp 6236 (6v 2.5a and +/-20v 0.5a ) and 6284 (20v 3a) when the half amp wasn't enough. Get the more recent ones, not the real old ones by Harrison with the colored hp logo. The 6284 has a safety crowbar too. They can be stacked in parallel or series so in principal I can get 60 volts if needed at 0.5a. No fans."
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 12, 2024, 02:59:44 am",
"content": "Quote from: MaxBishop on April 10, 2024, 05:38:31 amOKStill not sure what your project is but it sounds like you have something in mind that needs a power supply. Some people like to build a power supply, others are into refurbishing/repairing power supplies - both approaches can be good ways to learn and/or keep the budget down.Having said that, if everything is new to you then I think you might be better off starting with a few pieces of reliable and reasonably accurate pieces of test equipment. If you have a decent power supply and a decent DMM then when you measure V, I, and R you will have some confidence when your measurements and calculations agree, or some reason to relook the measurements and/or calculations if they don’t agree.It depends on how much adventure and experimenting you want to do - but if you are new to electronics and you want to learn and build stuff I’d recommend starting with a few decent tools. Along these lines, a used power supply might save some budget but for about $110 you can get a 30V 5A Korad that will be fairly accurate. Starting with a new working PS from a reliable seller is probably going to be a better experience than starting with a used PS but YMMV. A KA3005D from Amazon can be returned if it isn’t working or doesn’t meet your expectations. I’ve had one for about 10 years and it’s been rock solid; I bought a 2nd unit a couple years ago, and I gave another one as a gift to a new EE. Until you know what else you expect from a PS it’s likely all that’s needed.If you start with one Korad and you really need another PS you can buy a second unit. Sometimes it’s nice to have two of the same pieces of test equipment. You can compare measurements, you will be familiar with the UI on both, and if one is used in another location or is unavailable you have a spare."
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 12, 2024, 05:18:49 am",
"content": "Quote from: Electro Fan on April 12, 2024, 02:59:44 amI appreciate you taking the time to provide this feedback! I agree that I should get something that is known to work and go from there. Before I came to that conclusion, I bid on an HP PS on eBay but did not get it. It was kind of the (most recent) final straw for me.My project is simple, but I lack experience and knowledge. I want to make a simple machine surveillance system. Once the initial phase is working well, I’ll add phase two and so on. I’m starting with a Raspberry Pi, some simple diffuse reflective sensors and a bit of coding to count input vs output to get a solid waste count. I didn’t know how to power the sensors, so I Googled it, and it led me here.The power supplies listed here are overkill for what I need to do but now I have the bug and, need it or not I want a capable power supply for future projects. To your point on the Korad, I agree. Yet, I haven’t pulled the trigger because I’m envious of all the cool gear I’ve seen here!As far as my project goes, I was gifted an Allen Bradley 1606-XLP yesterday. It was in a junk pile at work. It is doing what I need for now and it’s affording me time to be picky on my future power supply. The power supply was simply to bench build the system. Acquiring the Allen Bradley was a surprise that, lucky for me, will work for the completed system. The search continues."
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2024, 08:22:27 pm",
"content": "Read Reply #5 and#6 in this thread:https://www.eevblog.com/forum/testgear/are-premium-scope-brands-still-justified/msg5448176/#msg5448176The thread and Reply #5 and #6 are about professional use but the concept applies at some level to enthusiast use also - if you can’t reasonably rely on measurements it can be extra confusing and time consuming."
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 13, 2024, 08:32:23 pm",
"content": "Quote from: Electro Fan on April 13, 2024, 08:22:27 pmThank you. More data points for me to consider. There just is no simple path. Well, I guess if funds are abundant that would be a game changer.Maybe, I should be asking the experienced folks here what investment amount is reasonable."
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2024, 09:50:44 pm",
"content": "It’s always good when asking questions here to give context. How much knowledge, experience, skill, budget, etc do you have to apply? What are the objectives, short term and long term? Test Equipment is like a tool - it can help a person solve problems, learn, and have a very enjoyable journey - but it can sometimes be like a drill to make rabbit holes.The question about a “reasonable investment” is a good one - but give some thought to that not just for a power supply or two, but for a bench full of test equipment that might surprising populate like rabbits. There are threads here you can find by searching that give advice on what new enthusiasts should consider with respect to various types of test equipment, tools, parts, consumables, etc.The forum members here are super helpful and will try to answer your questions but you will get the best answers when you frame the questions well with your context. Otherwise you might get a lot of enthusiastic answers from someone else’s context. Checkout a thread called “TEA”; there might be at least a couple - one short and one long. If you read thoroughly you might find, for example, some people will say you haven’t reached par on oscilloscopes until you have 19.After ~10 years of thoroughly enjoying EEVblog I’m about 15 short of par on oscilloscopes but I’ve made due with just (2) Korad power supplies. That doesn’t mean Korads are right for you - but I’m sure a person can learn a lot and get a lot done with <30 volts and <5 amps if the PS is easy to use, reliable, and accurate to a few hundredths of a volt and a few milliamperes - which the KA3005D is. It will probably be fine out of the box but there is a calibration routine you can use to dial it in with a DMM. But here you see the beginning of the rabbit hole. What if your DMM isn’t accurate?My suggestion would be start with a Korad PS and a couple decent DMMs (so you can measure voltage current at the same time), and climb in the rabbit hole.Once you see voltage and current on your two DMMs agree with the voltage and current readouts on the Korad and all four readouts agree with the calculations you made before hand for your Device Under Test you will be certified to climb in and out of the rabbit hole under your own power - just watch out for TEA symptoms."
},
{
"post_id": "",
"author": "Jwillis",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2024, 09:53:45 pm",
"content": "Mastech power supplies are now VOLTEQ.https://www.volteq.com/. The design has been around for years and are robust, reliable and very easy to repair and calibrate."
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2024, 10:08:33 pm",
"content": "fwiw, I think you want a linear PS and one with a DC output on/off button, not just an AC on/off button. And then you will want to see how cleanly the output turns on and off - which will be the sound of the rabbit hole telling you maybe you need to buy an oscilloscope to see and measure the waveforms.edit: and then you can post your scope’s screen captures of the PS output on/off, at which time you will realize you might need some different probe grounding techniques and accessories to avoid ringing, etc and help you confirm your PS has relatively low ripple, and so on and so forth…."
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 14, 2024, 06:05:47 am",
"content": "Quote from: Electro Fan on April 13, 2024, 10:08:33 pmWhat in interesting coincidence. Your timing is spot-on. I've been picking through this post tonight.https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/Mind blown.I can see the rabbit hole ahead, lol. I don't have a good power supply or oscilloscope, that I can find, anyway. I have my dads old scope around here somewhere. Regardless, already I can't seem to settle on just one of either. I have to remind myself this is what I do, jump in with both feet, usually with a fair amount of regret later. So, all the feedback I'm getting is most welcome! So, I have a Fluke, I believe it's a 17B or similar and a Klein Tools CL210. Hopefully, that's a decent set of starter DMM's. i can't seem to settle on the vintage power supply I want to purchase so I'm good with the KORAD. Quick question on that... I'm assuming the difference between programmable vs non programmable is well worth the $24 difference. Any thoughts on that are welcome."
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 14, 2024, 01:05:15 pm",
"content": "Given your questions and comments I don’t think you will regret jumping into the rabbit hole - but to get the best experience I suggest using a good ladder.The trick to getting a ladder that will enable an ee (non-degreed electrical enthusiast) to safely and enjoyably climb in and out of the rabbit hole, imo, is to get well grounded (haha) in Ohm’s Law. This means doing enough simple math to understand and reasonably predict the relationships that result from V=IR.Print the wheel and post it near your bench.https://www.formulacalculators.com/ohms-law-calculator/DC is a good place to start, then when you get to AC you can build on the foundational concepts and math learned with DC. AC will add things like RMS. Along the way you will start to recognize the concept of reactance as you distinguish impedance from simple resistance. The oscilloscope can help you visualize some of this and if it has useful math or measurement readouts the scope can help you connect the wave form insights to measurement insights. Things like Peak to Peak vs average vs RMS and 50 ohms vs 1 M ohms will start to show up over and over like markers on your rabbit hole ladder. This is a long way of saying you don’t need an expensive DMM but I’d get one with TRMS vs average RMS. When you see numbers like .707, 1.414, and 2.828 in your dreams you will know you are making progressAnd when this chart makes sense you will be another ladder rung proficiently into the rabbit hole.https://www.minicircuits.com/app/AN40-012.pdffwiw, from an early rabbit hole journey:https://www.eevblog.com/forum/testgear/fluke-17b-rms/For high voltage stuff, get a Fluke or Brymen. For low voltage stuff get one or two Aneng 8008 (save money and get good features with surprisingly good accuracy).The KA3005P adds the programmable PC interface and won’t cost much more than the KA3005D (but you might find the software a tad primitive). Both the D and P offer excellent value for the price.As for scopes, just take the elevator into the rabbit hole, get off on the Siglent floor marked HD.This advice is intended to save you time and money. Enjoy the journey, it is likely to be fascinating.edit: Maybe add one Aneng 8008 from Amazon to your Fluke and Klein collection and you are set on DMMs."
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 15, 2024, 05:12:31 pm",
"content": "Quote from: Electro Fan on April 14, 2024, 01:05:15 pmThis is all a bit intimidating... SOOO much information! I downloaded the charts. Thank you. After looking closer at the Fluke 17b I am wondering if that is actually the model I have. If it is I didn't realize it is so capable. When I return I'll have a look. As for the scope, I just don't know if I can manage something new in the budget. Even the 804 @ $439 is steep for my (initial) plans. And, it is out of stock, currently. When watching the Oscilloscope training vids I had myself convinced a used Tektronix would suffice. Is that not a good route to take? I'm a bit weary of buying used for such an important tool but I feel if I wait for the perfect tool at the perfect price I may never get started. Thoughts?* This advice is intended to save you time and money.Your consideration is much appreciated! Thank you."
},
{
"post_id": "",
"author": "donlisms",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 15, 2024, 07:47:39 pm",
"content": "There are many people who can't imagine relying on an analog Tektronix scope; it's not even digital! It does depend a lot on what you're doing, of course, and there are many people who *do* rely on them. I prefer my 485 as daily driver, unless or until there is some feature I need on the cheap digital scope.As to the fear of the unknown... you'd want to try and get as good a sense as possible of how well it's working before you buy, though there is always risk. I have a couple that were in great shape, and a couple that need work. The nice thing about it is the manuals are readily available and amazingly helpful. And while there may be obscure parts that fail, my guess is that you'd mostly need standard things like... capacitors. Plus there is a helpful community of experience out there. And videos. IOW, my view is once again \"don't be scared.\" :-)I also very firmly believe that your projects in your bench will tell you when it's time to get more gear, as opposed to trying to predict the future and what you might need someday. This is not necessarily a popular view, and doesn't always line up well with the Joy of Acquisition of New Shiny Baubles!"
},
{
"post_id": "",
"author": "wizard69",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 16, 2024, 12:49:44 am",
"content": "Quote from: MaxBishop on April 07, 2024, 08:59:10 amThat really isn't a lot of money to buy new. In fact I wouldn't bother with a lab supply.QuoteTimelines imply a project that is for money in most cases. As such it might make sense allocating more money for new hardware. On the flip side a project implies that you might know the exact voltages and currents required. If so fixed voltage industrial/commercial supplies are very cheap. You can literally find hundreds of such supplies from the regular distributors and they can be cheap.QuoteThere are numerous suppliers of lab type variable voltage supplies and they often come up for sale or auction. You can also go a bit upscale and get supplies used in test and measurement systems, often surprisingly cheap on auction or used. However the lack of information related to what makes this a pressing need really means we can't offer ideal advice."
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 16, 2024, 02:36:27 am",
"content": "Quote from: MaxBishop on April 15, 2024, 05:12:31 pmStill not sure what your project and overall objectives are but I’d recommend making it fun and educational.One easy low cost way to do that if you are just getting started is to stick with DC circuits until you get comfortable with Ohm’s Law. For this you can postpone an oscilloscope.Just get the Korad and use your existing DMM(s). Get a couple breadboards, a package of LEDs, and an assortment of resistors, plus some 22 gauge solid wire, and a wire stripper - all easy to get on Amazon. Make simple circuits in various combinations until you can predict (calculate) what voltages and resistances will result in what current as shown on the Korad readouts and as confirmed on your DMM(s).Watch some youtubes and post your breadboard layouts and test results and questions here. Total investment less than $200 including the power supply. (Or to really save on the budget just use a 9V battery - but I think the flexibility and functionality of the power supply will speed up the learning process and make it more fun).When you get Ohm’s Law working as expected you can move on to capacitors or maybe transistors or other components, or maybe try an Arduino if you are interested in digital and software. Lots of cool and useful stuff can be learned and built without an oscilloscope. If you go this route and decide you need or want a scope you can revisit the used analog vs new digital vs bothdiscussion. Enjoy the journey."
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 19, 2024, 05:31:13 am",
"content": "Quote from: wizard69 on April 16, 2024, 12:49:44 amThank you for the feedback, wizard69. My initial plan was to buy all used gear but it is looking like I may buy the KORAD for future testing but, for this project I'm using an Allen Bradley power supply.It isn’t something I’ll get paid for. Not the work I’ll put into it, anyway. It is something I want to use at work, though. Specifically, I want to prove there are other options than cost prohibitive industrial surveillance systems. I’ve considered using a PLC but I don’t know anything about the programming languages typically used.It’s only pressing because I’ve put a tentative completion date on it."
},
{
"post_id": "",
"author": "MaxBishop",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 19, 2024, 05:39:52 am",
"content": "Quote from: Electro Fan on April 16, 2024, 02:36:27 amThank you, Electro Fan. This sounds like a great plan for me. I'm going to utilize many of your suggestions. As far as my project, it's embarrassingly simple. I want to make a production machine surveillance system. The first step will be to count production pieces, input with one sensor and output with the other. Then, with some basic programming I can determine the % waste (raw material). If that all goes well, I’ll add another sensor at a different location in the process."
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2024, 12:24:53 pm",
"content": "Maybe just learn/experiment/prototype with an “Arduino sensor kit” fromAmazon. An alternative to the oscilloscope would be a low cost (~$20) logic analyzer from Amazon or eBay plus free Pulseview software. The Arduino or Rasberry Pi are excellent platforms for learning the intersection of electronics hardware and software; Arduino is a notch easier if you haven’t done much/any coding. You can power the Arduino from a computer USB cable as you program it, so even the Korad could move to Phase II. If you get TEA syndrome you will probably recognize the symptoms.https://sigrok.org/wiki/PulseView"
}
] |
2025-10-17T16:37:02.725598
| 31
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/$250-or-less-100mhz-oscilloscope/
|
$250 or less 100mhz oscilloscope? - Page 1
|
[
{
"post_id": "",
"author": "iLearn",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 11, 2013, 05:21:48 pm",
"content": "Hi EEV Blog community.I'm looking for my first oscilloscope to use on car projects and hopefully any car-related engineering projects when I start graduate school next semester (mechanical engineering). I read the rave reviews about the Rigol 50mhz being hacked to 100mhz, but even that is above my $250 budget.So, I wanted to ask you more experienced folks, what are some good 100mhz oscilloscope options for $250 or less in this new 2013 year? (the more portable the better)I'm also open to any diy kits as long as they have beginner-friendly build instructions."
},
{
"post_id": "",
"author": "ddavidebor",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 11, 2013, 05:45:24 pm",
"content": "All the analog you want, or some old hp with vey limited sample rate."
},
{
"post_id": "",
"author": "dfmischler",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 11, 2013, 06:19:46 pm",
"content": "I bought a Tektronix TDS380 oscilloscope (2 channel, 400MHz, 2GSa/s, 1kpt) on ebay for less than $250. With shipping. But it takes patience and knowing enough to decide what is a good deal when you see it."
},
{
"post_id": "",
"author": "iLearn",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 11, 2013, 08:45:56 pm",
"content": "Quote from: dfmischler on July 11, 2013, 06:19:46 pmThank you for your input guys and this is why I'm asking you more experienced EEVBloggers. I'm a beginner, but I want to get something that won't limit me 1-2 years from now as I become more knowledgeable in engineering and small electronic projects. I understand the Rigol DS1052E has been out a while now, is there a better 2013 alternative?(yes, I've searched the forum, but need some help since I'm a n00b)"
},
{
"post_id": "",
"author": "marshallh",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 11, 2013, 10:47:54 pm",
"content": "Quote from: dfmischler on July 11, 2013, 06:19:46 pmThe one in israel? Haha I linked that one to a few people."
},
{
"post_id": "",
"author": "dfmischler",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 12, 2013, 12:29:31 am",
"content": "Quote from: marshallh on July 11, 2013, 10:47:54 pmNo. Mine was purchased in, I think, 2010. Shipping from Israel to the USA would probably be a deal killer..."
},
{
"post_id": "",
"author": "Chalky",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 12, 2013, 02:52:11 am",
"content": "Quote from: iLearn on July 11, 2013, 05:21:48 pmHow about portability? I bought a Fluke 123 portable scope, which is great for cars, but the guy who sold it reckons that Picoscope is the way to go. Never used one of those myself, just thought worth mentioning."
},
{
"post_id": "",
"author": "iloveelectronics",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 12, 2013, 04:33:39 am",
"content": "I don't think you will be able to find any new 100MHz DSO for under $250, except for some unknown Chinese brands before any shipping fee is added. Your best bet would be to find some used equipment."
},
{
"post_id": "",
"author": "Corporate666",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 12, 2013, 09:03:36 pm",
"content": "There is no brand new scope with 100Mhz capability and some portability for <$250 - just not going to happen.Do you really need 100Mhz capability? I can't see many (any?) situations where that would be needed for automotive work."
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 12, 2013, 11:42:31 pm",
"content": "100 mHz ? Just place a very good Low Pass filter and you can use any scope that has a 1 sec/div timebase. A DSO would be best. Otherwise you only see a slow moving dot.Sorry, could not resist it. It is MHz. 1 mHz is 0.001 Hz.Buy a good secondhand analog Tek instead of a Chinese toy scope."
},
{
"post_id": "",
"author": "iLearn",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 14, 2013, 09:49:25 pm",
"content": "Ok guys,how about the best bang/buck PC USB oscilloscope with 100MHz accurate bandwidth?Recently, I'm playing with PropScope. It's very visually-comfortable to use because my laptop monitor is much bigger than most dso display screens. Unfortunately, the propscope is not accurate to 100MHZ..http://www.parallax.com/go/propscope"
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 14, 2013, 10:28:16 pm",
"content": "25 MS/s would be good for a few MHz real-time bandwidth. From what I gather from the extremely limited specs, its vertical range is also extremely limited (1/2/10/20 V full scale). Yet another toy.Some Picoscope models might be suitable for your application, but they're not going to be under $250. And the UI still sucks compared to a stand-alone scope for general purpose use. In my opinion, either pony up cash for a real DSO (DS1102E would probably be the cheapest that I would consider), or"
},
{
"post_id": "",
"author": "iLearn",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 15, 2013, 02:12:43 am",
"content": "Thank you to those of you who contributed your valuable and experienced advice.Per your advice, I've decided to wait a little more and buy something when I have a budget of ~$400. At the $400-$500 (USD) range, which 100MHz oscilloscopes do you guys recommend(including the PC-USB based interface ones)that have a bigger display screen compared to Rigol while also being battery powered and somewhat portable?"
},
{
"post_id": "",
"author": "iLearn",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 03, 2013, 10:33:56 pm",
"content": "I just purchased a Rigol DS1052E that is still in 50Mhz mode, but it feels like great quality and I'm excited to learn everything about it!Currently, I'm educating myself on all the functions and will test everything. One thing I'm pleasantly surprised is the fact that it's much more portable than I anticipated.YES, I have my 1st oscilloscope, woohoo!Btw, are there any fun automotive applications any of you have used this oscilliscope on for fun and testing, etc?"
},
{
"post_id": "",
"author": "Chalky",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "August 03, 2013, 11:45:58 pm",
"content": "Quote from: iLearn on August 03, 2013, 10:33:56 pmGood choice! In-car automotive is a bit hard with that scope unless you're able to run a mains lead out to the car - I used a portable scope recently when I was proving that my power windows were not causing significant drop in the voltage level at my bluetooth car kit."
},
{
"post_id": "",
"author": "iLearn",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 13, 2013, 07:30:08 pm",
"content": "Hey guys (and gals),are there any good oscilloscope tests you can recommend me beside what's in the manual to make sure this oscilloscope is working 100% perfect?"
},
{
"post_id": "",
"author": "dfmischler",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 13, 2013, 07:52:39 pm",
"content": "The classic test is to feed the scope a square wave or pulse edge with a fast rise time. Sub nanosecond would do it. The scope should show the edge rising at the scope's maximum slew rate (which for a 50 MHz scope should take around 7 nanoseconds or less)."
}
] |
2025-10-17T20:18:22.435442
| 17
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/$49-hitachi-v-1100a-for-repairs/
|
$49 Hitachi V-1100A for repairs - Page 1
|
[
{
"post_id": "",
"author": "jakeottinger",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 29, 2016, 02:47:56 am",
"content": "Hi guys and gals,I know it's not the best practice to be a newb and buy an oscilloscope that needs repairs but Looking at the photos I assumed the thing had been dropped on it's face and knobs were broken and that's all that was wrong. I powered it up and everything seems to work. I figured it would be a simple fix. However I'm having trouble sourcing the pots and knobs for this thing. Attached is a photo of the unit.Any ideas on where where to get these pots? I'm afraid to take it apart at the moment since my bench is a total mess and I'd enevitably loose parts until I clean up.Thanks for any and all replies!"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 29, 2016, 04:07:21 am",
"content": "Bugger, that's a shame it's so beat up.In the service manual the BOM may have clues to the value of the pots, type (lin or log) and the original supplier.http://elektrotanya.com/hitachi_v1100a_v1070a.pdf/download.html11.6 MBWait for \"processing\" to change to \"get manual\"."
},
{
"post_id": "",
"author": "jakeottinger",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 29, 2016, 04:20:19 am",
"content": "Thanks for the tip on waiting for Processing. I saw this page before but found no way to download. I guess I just had to wait a bit."
},
{
"post_id": "",
"author": "jakeottinger",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 08, 2016, 12:47:10 am",
"content": "So one of the destroyed pots is a RV2701 part number 8410393 EWK-ANAS 10k+10k. Where the heck can I find that? google only shows phone number reverse lookup for some reason. It's the level control without wich I'm assuming triggering will not happen. Do you think a stereo pot will work? It looks like a stereo footprint. Any Ideas? Thanks guys/ gals"
},
{
"post_id": "",
"author": "neko efecktz",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 08, 2016, 02:07:08 am",
"content": "Just a suggestion.Possibly find one of the same model online in a \"not working condition\" and salvage the parts from that.if there is board damage you may also be able to salvage boards from the Not Working unit.In the dropped unit check heavy components on the boards and especially the transformer.Bill."
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2016, 02:13:34 am",
"content": "Quote from: jakeottinger on July 08, 2016, 12:47:10 amIt's a dual concentric pot, not a single shaft pot like a normal stereo pot. (If you used a single shaft pot, you would have the same A and B trigger levels, which might not be so bad.)"
},
{
"post_id": "",
"author": "jakeottinger",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 08, 2016, 05:44:36 am",
"content": "I'm starting to doubt the ability of my go to supplier."
},
{
"post_id": "",
"author": "jakeottinger",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 08, 2016, 05:49:48 am",
"content": "@edavid do you happen to know if that pot is linear or log? Or at least how to test lin vs. log to find out?"
},
{
"post_id": "",
"author": "jakeottinger",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 08, 2016, 06:01:19 am",
"content": "@neko I already bought a non-working o scope, I understand the suggestion but I'm not about to buy another. I'd rather fix this one. Plus the only other Hitachi 1100A's out there sell for 4X the price I paid for this one. I'd much rather solder parts than steal them from other units that cost much more than I paid. I have thought about buying another donor but just can't bring myself to admit defeat just yet..."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2016, 06:17:27 am",
"content": "How good are you at mechanical repairs?Could the pot shafts be repaired?Some closeups of the removed pot might spur some ideas rather than trying to find something that's hard to obtain."
},
{
"post_id": "",
"author": "jakeottinger",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 08, 2016, 06:22:53 am",
"content": "https://www.dropbox.com/s/11jl68sas9p76k3/20160707_231934.jpg?dl=0sorry for the bad photography but the outer shell is completely severed."
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2016, 03:19:29 pm",
"content": "Quote from: jakeottinger on July 08, 2016, 05:49:48 amI would think linear, since zero trigger level is in the center... it's very unusual to find a log pot in a scope."
}
] |
2025-10-17T19:15:35.479565
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/$50-hot-air-station/
|
$50 Hot Air Station - Page 1
|
[
{
"post_id": "",
"author": "daveyk",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "April 30, 2017, 12:43:25 am",
"content": "Anyone have experience with these $50 hot air stations? Heck they look nice:https://www.ebay.com/itm/191557453776Sent from my iPhone using Tapatalk"
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 30, 2017, 01:30:57 am",
"content": "I have something similar for about 2 years now. The hot air seems reasonable. However the iron on mine is not crash hot. There is a significant air gap between the element and the tip, which really messes up the thermal capacity, so it doesn't get usedmuch(at all, really) - especially when I have a better iron on the bench. When I bought the unit, I looked at getting a spare element and found it was different to similar irons and while you can get replacements, they are not nearly as common. Haven't needed to replace the element yet - but that's hardly surprising since I don't use the iron. I have thought about getting a better iron that is electrically compatible - but I'm not motivated to muck around with that since I have a better iron right next to it. So I pretty much only use if for hot air.The iron also had one small issue which showed the level of quality of the unit:When I pointed this out to the seller, we went through a little dance on how to deal with it, which eventually worked out to me getting a partial refund. I bought a replacement plug from Jaycar to swap over, but I haven't fitted it yet.I did do the \"Don't turn it on, take it apart!\" to check out the internal construction - always a good idea on cheap Chinese stuff. While it wasn't aerospace quality, it was reasonable for the price and - more importantly - safe enough to use.It doesn't get a lot of use - but seems to be functional. You get what you pay for."
},
{
"post_id": "",
"author": "Jono427",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "May 01, 2017, 02:31:25 pm",
"content": "Looks like the hot air is the same (or similar) to this stand alone one. I grabbed a similar one, but haven't done work with it yet (just heat shrink). As Brumby said \"Don't turn it on, take it apart!\" - just look at the thread below too. Mine was fine and better than what Dave got in hid video.https://www.eevblog.com/forum/chat/deadly-wiring-fault-atten-858d-hot-air-rework-station/"
},
{
"post_id": "",
"author": "WaveyDipole",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 03, 2017, 10:43:44 am",
"content": "I've had my 858D for a few months now although I have only used it a handful of times so am still a relative novice. Since I already have a decent Weller iron, I only needed the hot air gun rather than a complete station. Besides, since my desk space is very limited, the less space used the better. I did take mine apart to examine before first use and did find a couple of problems. In particular, the fuse was on the neutral rather than the live AC input line so even if the fuse blew, the circuit would have been left connected to live. Also its worth checking all ground connections. However these issues are not difficult to fix. I initially practiced on a couple of old boards that I hadn't yet disposed of to get the hang of using it, although I'm still trying to get a feel for the optimum temperature and fan speed settings, which I'm sure will come with more experience. I think it does seem to depend to some extent on the type of solder used on the board but for most part seems to work very well. I also find that you have to leave it running for 3-4 minutes to get up to temperature properly before using it."
}
] |
2025-10-17T18:57:20.645853
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/$500-multimeter-recommendation/
|
$500 multimeter recommendation - Page 1
|
[
{
"post_id": "",
"author": "headingwest",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 19, 2013, 03:04:07 am",
"content": "Hi All,My better half has offered to buy me good multimeter, AUD$500'ish budget. What would your top recommendations be?I've been using the Victor 86E - a lovely chinese product - but it's time to step up a bit.Thanks for your help."
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 19, 2013, 03:14:55 am",
"content": "I guess you have to ask yourself what you want to do. $500 might be much better spent on two multimeters. One is not enough many times and four can be required for some things.If you really must spend $500 on only one multimeter then a nice one would be this:http://www.testequipmentdepot.com/agilent/multimeters/u1252b.htmHard to beat it for features and quality.If you think you might want to have two meters then I would suggest a Brymen BM869 and a Brymen BM257 both with their optional USB cables. Two great meters, both with good safety with the BM869 having the highest safety rating in the industry.Of course there is Fluke......"
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 03:23:15 am",
"content": "If you're looking in the $500 range, then I'm going to adamantly insist on two $250 multimeters. There's not much you're going to get in the $500 meter that the $250 one won't have. Go for dataloggers if you can find decent ones."
},
{
"post_id": "",
"author": "Fsck",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 03:27:09 am",
"content": "Are you limited to just one meter or the budget?(I'd hope the budget)If handheld, I'd get 2 decent meters. Not sure what the market is like, but for that price (in Canada), you can get anywhere between 2 to 4 secondhand Fluke 87 types. Or something like a U1272a + UT61E or a BM869 + UT61E.I'd personally probably go with a BM867 with logging kit+ 2*UT61E. (this fits if we convert AUD to CAD and buy shipped to Canada)"
},
{
"post_id": "",
"author": "Ferroto",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 03:36:54 am",
"content": "You can get yourself a Rigol 1052E for less then $500. I'd just stick with a Fluke 87, $500 bucks is abit much to spend on a meter."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 03:39:13 am",
"content": "I think its better to tell us a bit about your self like are you hobbyist, electrician etc, and your normal usage for this new upcoming meter."
},
{
"post_id": "",
"author": "jmole",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 03:42:26 am",
"content": "unless you're considering a bench meter, you should look into those handheld scopemeters by fluke. Believe you can pick up a used one on ebay for around $500 depending on the model."
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 04:32:06 am",
"content": "for that price you can get two 34401 meters on ebay.can't go wrong with those..."
},
{
"post_id": "",
"author": "headingwest",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 19, 2013, 04:38:48 am",
"content": "I'm a keen hobbyist with one years experience working with microchips and small boards. Mains voltage for testing faulty equipment but not design.I need to repair the coffee machines we import:http://www.coffeemachine.com.au/product/hlf-fusion/I am working revision 3 of a control board to let android phones control coffee machines:http://divapid.com/While trying to build a robot - like most hobbyist are:http://jimsrobot.com/So what do I really need:instructions in English - I'm sick of guessing what the manual sayslogging preferredprecise small voltage / currentdigital troubleshooting toolsplus stuff I haven't thought of yet but will need in the next few yearsnew not second hand - it's a gifta very understanding wife"
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 19, 2013, 05:14:27 am",
"content": "Based on what you want to do I repeat my recommendation for these two meters:http://www.tme.eu/en/details/bm257/portable-digital-multimeters/brymen/#$111 USD plus shippingplus the USB cable for logging when you need it:http://www.tme.eu/en/details/kitbrua-20x/meters-software/brymen/$31 USD plus shippingor get it from Franky, iloveelectronics here on this forum, when he gets it back in stock for $135 shippedplus he has the USB cable too when he has the BM257 in stock, I forget the pricePlus get the Brymen BM869:http://www.tme.eu/en/details/bm869/portable-digital-multimeters/brymen/#$240 USD plus shippingand the USB cable:http://www.tme.eu/en/details/kitbu-86x/meters-software/brymen/$52 plus shippingAll in it should come under the $500 price including the shipping.With these two really well built meters you will be able to have high accuracy and high safety plus the logging of both meters at the same time to a computer. The dual temp measurement of the BM869 will come in handy with the coffee machines as will the high safety of the meters when you are poking around the high power heater controls.So you will be able to log current and voltage at the same time and figure out power, or log voltage or current vs temperatures, etc....The BM869 is for high accuracy and high resolution and with dual temperatures, and the BM257 is the small one for poking around in smaller places and has a non-contact voltage detector to let you know if you have a live circuit before you actually touch something. Both should take a beating."
},
{
"post_id": "",
"author": "Ed.Kloonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 07:28:08 am",
"content": "Yeah also want to say, for $500, go with two (different) meters. Unless you have a reason to need one meter worth half a grand."
},
{
"post_id": "",
"author": "M. András",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 08:29:02 am",
"content": "Quote from: free_electron on April 19, 2013, 04:32:06 ami dont find any of them below 500 on ebay"
},
{
"post_id": "",
"author": "Fsck",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 08:41:55 am",
"content": "Quote from: M. András on April 19, 2013, 08:29:02 amme either"
},
{
"post_id": "",
"author": "KJDS",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 09:26:10 am",
"content": "Quote from: Fsck on April 19, 2013, 08:41:55 am^^^Wot e Sed^^^Usually at least £350 each"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 09:36:53 am",
"content": "Its obvious Vincent did his last ebay transaction at yester-years."
},
{
"post_id": "",
"author": "eevblogfan",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 09:39:07 am",
"content": "heysorry but I think you went nut'soplease have a look at the lovely 2'nd hand HP3478Acan be easly picked up for 100~150$ , so 2 can easly be bought ,and besides , If you need two top end multimeters for that price ( and new ) I'll suggest buying 2X 87V from some ebay seller , you can easly tell one that he'll do 2 for 500$ including shipping , I did found one for 147$ including shipping but that's rear , so please go for one of those , I would but some 3610A and two 3478A if I was you ,Cheers !"
},
{
"post_id": "",
"author": "bingo600",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 12:16:52 pm",
"content": "Quote from: headingwest on April 19, 2013, 04:38:48 amnew not second hand - it's a giftWell the New criteria , prob. rules out any 6.5 digit meter.The understanding wife ... Is prob gonna cost more than $500 (in shoes)/Bingo"
},
{
"post_id": "",
"author": "ddavidebor",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 12:28:26 pm",
"content": "I suggest you a good fluke or agilent plus an hp 34401aSo you have one strong and portable, and another one advanced and super accurate"
},
{
"post_id": "",
"author": "commongrounder",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 07:19:42 pm",
"content": "Fluke 289. Hands down best. Logging with trendplot built in. Measures just about everything. I treasure mine."
},
{
"post_id": "",
"author": "olsenn",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 08:12:30 pm",
"content": "Check out the Rigol DM3058E (http://www.rigolna.com/products/digital-multimeters/dm3000/dm3058E/). It costs $449 new, and is definitely your best choice unless you get a steal off some used Agilent stuff on eBay. The DM3058E is the same as the regular DM3058 except it doesn't offer GBIB or LAN connectivity (It still can be controlled remotely via USB or RS232).It is 5 1/2 Digits, 0.015% DCV accuracy; 240,000 count, and 123 readings/sec. It has extremely advanced features for a DMM including histogram plotting and other statistical analysis, can measures in dbm and other less commonly used formats when desired, features all the common measurements as well as capacitance, junction (diode) voltage, frequency, custom sensors; it has a continuity buzzer, and the display is pretty nice.If you are looking for a handheld meter, I'd highly recommend looking for a used Fluke 87 on eBay, or even a 28-II. One thing I would recommend though, if purchasing used, is to pick up some precision voltage references from TI free samples page to ensure basic calibration. Some precision resistors can also come in handy for calibrating resistance/current measurements."
},
{
"post_id": "",
"author": "kxenos",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 10:50:13 pm",
"content": "My beloved Beauty I Take Care Honestly off, decided (after speaking with her mother, I believe) that our family budget can afford a bench multimeter some months ago, so I bought a Keithley 2000 from ebay. There is also a forum member that sells a keithley 2015 in a very reasonable price, if he still has it. My point is, if you have a chance to get something of 500$ don't waste the opportunity for things that you could get anytime. Plus a decent bench DMM is a nice bit of kit to have."
},
{
"post_id": "",
"author": "bingo600",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2013, 10:56:25 pm",
"content": "Quote from: kxenos on April 19, 2013, 10:50:13 pmI can only second that , and i got a 2055 from KJDShttps://www.eevblog.com/forum/reviews/keithley-2015-teardown/msg213757/#msg213757It was calibrated in May 2011 , and is spot on my 10v Geller reference.Just get a probe set from ebay or ... If you decide to get the 2015 , there's just the 2015 in the package./Bingo"
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 19, 2013, 11:09:29 pm",
"content": "You guys keep missing one important point. He said NO USED EQUIPMENT.A new Fluke 289 is $600+A Fluke 87V is a nice meter but lacking some features for the price.The Brymens I mentioned cost less together with the PC cables and software than the Fluke alone. Two meters and each with PC software for less than the price of one 87V. It seems a no brainer to me and you can't beat the safety rating of the Brymen BM869. It is built to very high standards and is very accurate too."
},
{
"post_id": "",
"author": "ddavidebor",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 20, 2013, 08:36:44 am",
"content": "Used precision 5+ digit multimeter are much better than new"
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 20, 2013, 08:47:20 am",
"content": "Quote from: headingwest on April 19, 2013, 03:04:07 amAgilent U1272Ahttp://www.triosmartcal.com.au/2251-agilent-u1272a-dmm-digit-water-dust-resist.html"
},
{
"post_id": "",
"author": "bingo600",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 20, 2013, 05:19:16 pm",
"content": "Quote from: EEVblog on April 20, 2013, 08:47:20 amI'd check if the PSU + Free meter also applies to OZhttp://uk.farnell.com/agilent-technologies/e3610a-u1272a/bundle-psu-bench-30w-free-u1272a/dp/2250753Almost reachable for$500/Bingo"
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 20, 2013, 10:09:46 pm",
"content": "Quote from: EEVblog on April 20, 2013, 08:47:20 amAh c'mon Dave! We are trying to get him to follow your advice to get two meters!"
},
{
"post_id": "",
"author": "ddavidebor",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2013, 11:46:25 am",
"content": "I have the solution!!!Buy a 250$ meter and use the remaining 250$ for buy something sweet for your girlfriend-wife"
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 21, 2013, 11:49:03 am",
"content": "Quote from: Lightages on April 20, 2013, 10:09:46 pmBut he asked for ONE!Hardly anyone in here gave him the advice he was asking for, so I did"
},
{
"post_id": "",
"author": "Ed.Kloonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2013, 12:12:20 pm",
"content": "Quote from: EEVblog on April 21, 2013, 11:49:03 amTrue dat. A few of the accessories on the linked page and you're pretty spot-on I thought."
},
{
"post_id": "",
"author": "ivan747",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2013, 04:24:37 pm",
"content": "Remember this is a gift, SO, when you pick your gifts you generally do not ask for:Used stuffThings that weren't offered to you (getting 2 meters instead of 1, a scope etc.)Extra accesories (but that is not a strict convention)That's how I see it."
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 21, 2013, 04:38:52 pm",
"content": "I did suggest the U1252B!That would be my preference for ONE meter."
},
{
"post_id": "",
"author": "ivan747",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2013, 07:45:48 pm",
"content": "It all depends on his needs, really."
},
{
"post_id": "",
"author": "olsenn",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 21, 2013, 07:58:02 pm",
"content": "I'm still sticking to the DM3058E, haha; but if he's specifically looking for a handheld that Agilent should do nicely (I still prefer Fluke, what both are great meters)."
},
{
"post_id": "",
"author": "nanofrog",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2013, 08:00:31 pm",
"content": "Quote from: Lightages on April 21, 2013, 04:38:52 pm+1"
},
{
"post_id": "",
"author": "ddavidebor",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2013, 09:52:26 pm",
"content": "People, and an high end gossen metrawatt?"
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 21, 2013, 10:13:17 pm",
"content": "Quote from: ivan747 on April 21, 2013, 04:24:37 pmYep, and he's from Oz. So it's gotta be from an Oz supplier, or possibly ebay (but why would you do that and get no warranty?)So what would go get if offered ONE meter up to the value of AU$500?I vote the U1272A. Feature packed, and you get a nice cal certificate with values."
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 21, 2013, 11:06:37 pm",
"content": "Just curious Dave, why the U1272A over the U1252B for you?"
},
{
"post_id": "",
"author": "peter.mitchell",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 22, 2013, 08:42:37 am",
"content": "I WAS going to suggest the Gossen Metrahit Energy, because it can do volts + amps at the same time, so it's like getting two metersthen i looked at the price D:"
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 22, 2013, 09:17:13 am",
"content": "Quote from: Lightages on April 21, 2013, 11:06:37 pm- Completely new design- More rugged- Better IP rating- Low Z mode- Smart Ohm mode- tighter count spec- 300 hours vs 36 hours battery"
},
{
"post_id": "",
"author": "Wytnucls",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 22, 2013, 09:21:12 am",
"content": "...and the big one: internal data logging. 10,000 versus 100 points only for the 1252B.Also, CAT rating up to 3000 meters and there is a BT module available."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 22, 2013, 09:31:01 am",
"content": "Quote from: Wytnucls on April 22, 2013, 09:21:12 amI think the BT is available for both.Complete no-brainer though really, U1272A wins hands down."
},
{
"post_id": "",
"author": "Wytnucls",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 22, 2013, 09:46:11 am",
"content": "Features in favor of the 1252B:50,000 count on both displays (dual display)Square wave generatorCapacitance 100mF high range instead of 10mF on the 1272Aand yes, the BT adapter is available for both."
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 22, 2013, 06:57:50 pm",
"content": "It looks like it comes down to personal preference. But seeing as I have never seen nor used either I only have a weak opinion this one."
},
{
"post_id": "",
"author": "mark5009",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "April 24, 2013, 10:21:38 am",
"content": "I'm also from Oz (Sydney). I got a used Fluke 8842A (no RMS module) delivered for around $200 from eBay. 5-1/2 digits and lovely to use. Then you have $300 left over to get yourself something else, perhaps newer? But, unless you have a good idea of what you are after, maybe second hand and flexible is the way to go?.. m."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 24, 2013, 10:49:19 am",
"content": "Quote from: Wytnucls on April 22, 2013, 09:46:11 amNot close to making up for the poor battery life and other stuff IMO."
},
{
"post_id": "",
"author": "nanofrog",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 24, 2013, 04:46:30 pm",
"content": "Quote from: EEVblog on April 24, 2013, 10:49:19 amFWIW, I don't find it much of an issue for bench use. But I keep an eye on the battery indicator (I've figured out how low I can go before the meter to goes flakey), and swap it for a fresh one.For field work OTOH, I could see it as a notable issue."
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 24, 2013, 05:32:54 pm",
"content": "Hmmm, I thought your many complaints about the U1272A in your review would make it less of a recommendation.The annoying beepOff position on the dial (personal preference)Buggy firmwarePulse measurement error with DC offsetCapacitor measurement \"big fail\" on low caps, and errors on others \"way out there\"Overload protection recovery problemsYeah the battery life on the U1252B is horrible, but it will use a rechargeable and you can leave it on charge anytime you aren't using it. It doesn't log like the U1272A. It does have other features the 1272 doesn't. Maybe it has firmware bugs too but they haven't been mentioned that I can remember.Actually, for either of these, $400+ they should be damn near perfect. I see little to criticize on my Brymen BM869. It just works and has no bugs and has a higher CAT rating too!Maybe he should just get the Fluke 87V and be done with it."
}
] |
2025-10-17T20:23:24.041427
| 48
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/$55arduino-replaces-$18k-labview/
|
:: ... $55arduino replaces ... $18k labview - Page 1
|
[
{
"post_id": "",
"author": "3roomlab",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 01, 2015, 12:26:36 pm",
"content": "so i was bored, randomly reading things off internet ... and then i read thishttp://pheloniusfriar.dreamwidth.org/45390.htmlwe would all expect expensive high tech stuff to be well supported ... but then again LOLz happened"
},
{
"post_id": "",
"author": "electr_peter",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 01, 2015, 02:15:31 pm",
"content": "One guy who is not happy about $18,000 National Instruments 2.26 GHz Quad-Core Labview DAQ systemIt is a clear example of \"In some situation it does not matter what it is called or how much it costs as long as it works.\""
},
{
"post_id": "",
"author": "SL4P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 01, 2015, 02:22:52 pm",
"content": "I used to work for a large minicomputer manufacturer, and while technology marches on, and implementing more powerful hardware is not a problem because of price--- I'm amazed at what a lot of people don't know is possible with an 8/16-bit PIC or Arduino platform.If you flip back 30 years - there were multi-user 'mini-frame' systems with 20 or 30 concurrent users, disk, printing, and other activities - running on a processor/memory that was comparable to a high-end ATMEGA or PIC16 chipset.Maybe it's something they put in the coffee at university CS/SE cafeterias?"
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 01, 2015, 04:07:48 pm",
"content": "I remember when people were trying to convince me to use a Data General DOS 1.05 instead of a 486 PC, that sounds so quaint now"
},
{
"post_id": "",
"author": "3roomlab",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 01, 2015, 09:16:36 pm",
"content": "i wonder if NI came around to fix their embarassment ..."
},
{
"post_id": "",
"author": "SL4P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 01, 2015, 09:36:59 pm",
"content": "NI gear is well made and respected (or it used to be), but has always been cantankerous and fragile to setup and keep running.Really intended for set & forget applications. If you breathe on it, something will fall over!"
},
{
"post_id": "",
"author": "max_torque",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2015, 12:26:14 pm",
"content": "So it seems that if you just need to do a simple task, then a simple solution is, er, simpler..... wow who'd of thought it eh! ;-)(ie, both an $10 arduino and a $100M super computer can flash an LED, if that's all you want to do. But if you want to say decrypt 1000 parallel streams of 128b SSL encoding in near real time, then the arduino isn't going to perform quite so well)"
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2015, 04:35:03 pm",
"content": "Quote from: electr_peter on March 01, 2015, 02:15:31 pmI think that picture summarizes what I think about NI."
},
{
"post_id": "",
"author": "Sigmoid",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 02, 2015, 05:02:02 pm",
"content": "$55?!Someone got robbed, apparently."
},
{
"post_id": "",
"author": "3roomlab",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 02, 2015, 05:24:30 pm",
"content": "Quote from: NANDBlog on March 02, 2015, 04:35:03 pmgeez ... they are that bad huh? or the bosses skimped and didnt hire enough support engineers ... i would think its the guy up there insidei have a friend who happen to visit google some years back, he said the work environment is ... like wow."
},
{
"post_id": "",
"author": "mtdoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2015, 05:39:11 pm",
"content": "Sounds like a bit like just using the right tool for the job.From the other side:In the early 1990's I was in charge of running an undergraduate neurobiology lab course at UC Berkeley. We had one lab exercise that involved doing EEGs and measuring evoked potentials. They had been using the same dedicated EEG set up for 25+years. The equipment was far outdated and there was only one set up to share between all the students. I was tasked with finding a modern replacement.I contacted several companies making EEG equipment - all with complete solutions, costing about $30K for one set up. These were designed for medical use. There was nothing designed for a teaching lab that had the sophistication to measure the kind of evoked potentials we wanted.So - I did some research and found out that NI data Acquisition boards could be installed in the new Mac computers we were just then about to purchase for student use. For about $2K for LabVIew and $500 each for the DAQ boards we could potentially have numerous setups to do what we needed.I spent the next 6 months learning LabView and developing the application for the lab. It was a great success. We saved $25K and now had 5 setups instead of one and with a student friendly computer interface.Furthermore I went on to use DAQ boards with more computers on carts and Labview to develop other \"virtual intstruments\" to replace some outdated traditional hardware for other lab courses.Clearly NI products and LabView are not the right tool for every job but for some jobs it is and can actually result in a large savings spent on lab equipment."
},
{
"post_id": "",
"author": "3roomlab",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 02, 2015, 05:43:14 pm",
"content": "maybe the part which they implemented required very specific tolerances (smashing atoms!) ... and the NI engineer assign have no clue ... nanovolts?what kind of measurement ranges did you involve? mtdoc?"
},
{
"post_id": "",
"author": "mtdoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2015, 06:11:34 pm",
"content": "Quote from: 3roomlab on March 02, 2015, 05:43:14 pmWell, it was microvolts to millivolt range amplitude,with up to kHz frequencies -so nothing super high speed. We did need minimum 12 bit amplitude resolution as I recall.We didAuditory Brainstem Responseand other types ofsensory evoked potentialssuch as visual and somatosensory.We also didp300 evoked potentialsNone of these required super hi speed DAQ but they did require custom software to coordinate the stimulus with the acquisition, average out noise over several thousand samples, etc. This was being run with the PC hardware of the era (i.e. donkey slow compared to todays hardware)."
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2015, 06:22:16 pm",
"content": "Seems like someone missed the boat in not being fully Labview conversant before going to a limited time expensive one shot test opportunity. It is nice that the Arduino interface was able to save the day, and if he had to learn Arduino on the spot it is a nice plug for the Arduino interface, but not something I would want to bet my coveted time window on."
},
{
"post_id": "",
"author": "electr_peter",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 02, 2015, 06:28:03 pm",
"content": "This story is an obvious case of the right tool for the job.Sometimes you use a tool and find you have exhausted it in one or another way, specs simply are slightly lower than what you need. Other times tool are just too expensive/hard to use/time consuming/overcomplicated/too heavy/etc. but it could do the job.Original story has more details. Equipment used in a experiment was an absolute mess - clever engineers just try to do what they can to accomplish the required goals. NI instrument in question was used for one of weird integration functions and failed in that situation. It was mentioned that experiment setup was tried first time and will be improved and more integrated in future.NI instrument was an overkill in this story and it failed to do some designated function which was replaced with overpriced ($55) Arduino board. Scientist/engineer was flipping a bird at NI because of very demanding schedule on the site."
},
{
"post_id": "",
"author": "Dave Turner",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 02, 2015, 07:32:59 pm",
"content": "Now that's a Macgyver"
},
{
"post_id": "",
"author": "Harrkev",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "March 04, 2015, 10:06:23 pm",
"content": "Quote from: Sigmoid on March 02, 2015, 05:02:02 pmIf you RTFA, that included an Ethernet shield. So, no, not really."
}
] |
2025-10-17T19:46:05.908912
| 17
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(-bjt-amplifier-circuit-v_be-negative-)/
|
[ BJT amplifier circuit, v_be negative ] - Page 1
|
[
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 04, 2012, 04:17:39 pm",
"content": "Hi,I am learning about BJT transistor and I understand them quite well know... I guesseduntil I saw the following simple circuit:http://www.reconnsworld.com/audio_simplepreamp.htmlWhat I do not understand: passed the first AC coupling capacitor, the voltage can benegative. Usually, the transistor is base voltage biased in such a way there is an offsetso that negative voltages are not an issue. But in this schema, there is no offset. I builtit, and it works: I get some Vbe < 0 and get a correct Vc with no clipping...How is it possible, can someone explain to me what I am missing? I guess there issomething with a current involved from Vcc to C1 as the voltage accross C1 becomes< 0, and that it acts as the Vbe offset I do not see... but not clear at all to me.Thanks!Best regards,texane."
},
{
"post_id": "",
"author": "Tube_Dude",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 04, 2012, 05:40:10 pm",
"content": "HiTake out of circuit C1, and check, if then, you have around 0,6 Volts VBE, if not, or you have a faulty transistor, faulty R3/R2, or wiring error..."
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 04, 2012, 05:51:04 pm",
"content": "Thanks for answering.I think I found my mistake... I left the oscilloscpoe to AC coupling and obviously was seeing'negative' voltages instead of the real one... for my defense, let say this is an old scopeOf course, having Vbe negative would have clipped the voltage on the other end.Best regards,Fabien."
},
{
"post_id": "",
"author": "Tube_Dude",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 04, 2012, 05:54:10 pm",
"content": "Happy End!!"
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 04, 2012, 05:55:57 pm",
"content": "yes, but I spent a lot of time thinking that my understanding of BJT was wrong or incomplete...still a lot to learn by the way"
},
{
"post_id": "",
"author": "Tube_Dude",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 04, 2012, 06:03:33 pm",
"content": "We all (almost all...), learn with our mistakes..."
}
] |
2025-10-17T20:35:36.405688
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(-comparator-with-npn-transistors-)/
|
[ comparator with npn transistors ] - Page 1
|
[
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 17, 2010, 08:36:50 am",
"content": "Hi,I am working on a small project forwhich I need to compare a voltageto 2.5v. The compared voltage iscalled Vin. If Vin is more than 2.5,I need a Vout to 5V, otherwise to 0V.I do not want to use a comparator,but transistors for learning purposes.I was thinking about using the avoltage divider so that Vin is scaledfrom [0, 5 volts] to [0, 1.4] thus mycomparing voltage become 0.7v (ie.was 2.5v in [0,5] becomes 0.7v in[0,1.4]) which I plug to an opampwhich is linked to the transistor Basepin.< 0.7v wont switch the transistor ON,otherwise it will. I can replace the opampwith another transistor.Is the basic idea good? Any commentwelcome! I have read relying on theBaseEmitter voltage drop is not a goodthing...Thanks for helping,"
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 17, 2010, 12:12:49 pm",
"content": "You want to use an OpAmp, but not a comperator?I'll tell you a secret. A comperator is an OpAmp, just specially optimised for working as a comperator. So I don't see the learning experience here - replacing a comperator (which is an OpAmp) with an OpAmp, albeit one not specially suited for comparing."
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 17, 2010, 02:32:43 pm",
"content": "hi,forget about the opamp, and replace itwith a transistor providing the samevoltage (ie. Ve = Vb - 0.6) but with again in current. My question was aboutrelying upon the drop of 0.6v (0.7v) atVbe.Thanks,f."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2010, 05:53:11 pm",
"content": "You'll need several transistors, not just one.Google for 'differential pair' and learn the basics of differential amplifiers which is what goes into op-amps and comparators.Look at the datasheet for a comparator and op-amp IC and base your design on it.Accept, that your circuit will never be as good as an IC because none of the transistors are matched."
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 17, 2010, 06:03:59 pm",
"content": "ok, thanks for pointing me to the right direction.Thanks,"
}
] |
2025-10-17T20:43:45.214286
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(-different-grounds-)/
|
[ different grounds ] - Page 1
|
[
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 19, 2010, 02:09:28 pm",
"content": "hi people,let say I have a device D0 I want tomonitor the clock and data signals.The device is powered by a 5v/10Macurrent source I have no access to(except to power D0 of course)To monitor the signals, I plan to usea pic microcontroller. Let call itD1. I will have to power it withanother current source.Let say the D0 signal frequencies arefar below the one the pic can handle,so no problem for that point.My question: since the ground is notthe same in the 2 cases (cannot powerD0 and D1 from the same source), howcan I measure a D0 voltage from D1?Am I misleading?The question may be basic, but I donthave any clue... was thinking aboutsomething like a relay, but it wouldnot be possible due to relatively highfreqs...Thanks for answering,Regards,"
},
{
"post_id": "",
"author": "jahonen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 19, 2010, 03:25:32 pm",
"content": "How much voltage difference you have between the grounds? If it is not extreme (less than 1 kV), then maybe AD/TI digital isolators are the solution you are looking for. Optoisolator is also possible but problem there is a rather large drive current required by the optoisolator LED.Or, if the ground voltage difference is only a few volts, then even a RS-485/422 receiver / ordinary comparator may work.Regards,Janne"
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 20, 2010, 07:15:14 am",
"content": "Hi,Thanks for replying.Some friends told me that by linkin the2 grounds together, it will do the job, ieI will be able to measure both voltages.But I don t understand it...with this newmixed ground, how can the Vcc remainon the same value?Would you have any link, ref, course...handling this kind of topics? (ie. having2 current and voltage sources inside thesame circuit?)Regards,"
},
{
"post_id": "",
"author": "mkissin",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "February 20, 2010, 10:41:39 am",
"content": "As long as you connect the ground of D0 and D1 together, your PIC will be able to read the other digital signals from D0 just fine. It actually doesn't matter that they are being powered by two different sources.All voltages in electronics are relative. As long as all your devices agree on what voltage to call zero, it works. Only when they cannot agree on the zero voltage level do you need an isolation barrier.I'm assuming, though, that your PIC is also being powered with a 5V source. If it's not, then you would also need to be careful that it will accept the 5V logic levels used by D0 (i.e. a 3.3V PIC probably wouldn't accept 5V logic, unless you used current limiting resistors or level translators)."
},
{
"post_id": "",
"author": "jahonen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 20, 2010, 11:50:53 am",
"content": "Connecting the grounds together is easiest solution, but that is not always possible due to isolation/ground voltage difference or safety reasons.Vcc does not need to be exactly same for both circuits, but one must make sure that levels are compatible so that logic levels are correct. Small voltage differences are usually not significant.Regards,Janne"
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 21, 2010, 10:20:18 am",
"content": "Hi,Thanks for replying, your answers are of greathelp since I have hard time understanding somekey concepts (more of a software guy...)I think I understood all this, I will confirm bypracticing a bit...Regards,Fabien."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 26, 2010, 09:30:33 pm",
"content": "you should be able to connect the two grounds together, he you could even connect VCC of one to the ground of the other but that would make it difficult for the the circuits to interact, ground is essentially just that the 0 and reference point, provising it is actually negative (or even if not) you can connect it to your main earth, providing you don't connect two power delivering lines together at the same time. if your sampling one circuit with you pic circuit ensure you are not in a position where two voltages will clash, this is ually avoided by making a connection between the two via a pullup resistor and/or IC's that have an output transistor with an unconnected collector so that the two supplies never \"meet\" directly."
}
] |
2025-10-17T20:43:38.063355
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(-high-(gt20kv)-back-emf-suppression-)/
|
[ high (>20KV) back EMF suppression ] - Page 1
|
[
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 03, 2012, 05:43:24 am",
"content": "Hi,I am working on a project where I load capa then discharge them rapidlyin a coil using a MOSFET to produce a high magnetic field. To be efficient, oneconstraint is to make the field as short (in time) as possible. Thus, di/dt isvery high, and the back EMF can reach up to 20kV... and I did not find any'flyback' diode that can handle such a voltage. I found some monster diodesthat can handle 6kV, but they burned up during the first test ... :/I try to change the switching MOSFET by an IBGT, but same problem asabove.Maybe there are some well known techniques to address this issue, and yourhelp would be very appreciatedCheers,Fabien."
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2012, 06:35:45 am",
"content": "Maybe look at TVS diodes or MOVs"
},
{
"post_id": "",
"author": "TerminalJack505",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2012, 09:01:18 am",
"content": "Your diode will try to clamp the voltage at about a volt so the problem is really the current. More precisely, the power that's dissipated by the diode.You can try a diode with a higher power rating.And/or you can clamp at a higher voltage by putting several diodes in series. This will spread the power dissipation equally across the diodes.A small value resistor in series with the diode is another option. This will limit the current but raise the voltage."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2012, 09:10:39 am",
"content": "Quote from: TerminalJack505 on April 03, 2012, 09:01:18 amWill a series of diodes also increase the total break down voltage proportionally ?"
},
{
"post_id": "",
"author": "TerminalJack505",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2012, 09:19:14 am",
"content": "Quote from: BravoV on April 03, 2012, 09:10:39 amAs in the reverse breakdown? That I don't know.It shouldn't problem in this particular case, though."
},
{
"post_id": "",
"author": "Neilm",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2012, 06:32:40 pm",
"content": "There are some high voltage diodes used for rectifying at high voltages but they are not that easily available. One I have seen is the SL500 that can take 5kV. I think that it does go up to 12kV. I don't know how much power they can take. I have seen diodes that go up higher than that (>20kV) but I don't know the part number for that. I also don't know where you could get it. I used these in a project and ended up speaking to specialist distributors.YoursNeil"
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2012, 06:52:22 pm",
"content": "Do you have a circuit diagram? I don't understand where your diodes are placed and what function they are performing.(For example, back EMF suppression usually involves putting a diode in parallel with the coil to shunt the collapsing field current away from the rest of the circuit and prevent an EMF building up. What is the configuration here and why does the diode need 20 kV capability?)"
},
{
"post_id": "",
"author": "TerminalJack505",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2012, 06:53:43 pm",
"content": "I'm confused as to why everyone seems to think the diode needs to have a high voltage rating. The voltage rating of the diode just needs to be greater than the voltage that the capacitors are charged-up to before dumping their current into the inductor.The whole purpose of the flyback diode is to prevent the EMF voltage spiking up to, in this case, 20kV. It does this by clamping the voltage at its forward voltage, Vf. This will just be a volt or two in this particular case.So I'm pretty sure what is killing the diode is the heat dissipated during flyback. If the current through the inductor was 10A when the MOSFET was turned off then this 10A is going to flow through the diode. 10A * 2V is 20W of power, which the diode turns into heat."
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 06, 2012, 11:12:03 am",
"content": "Hi,Thanks for your replies.I join you a partial schema, but I have to take a look at theactual capa value so that I can compute the actual currentand the power that needs to be dissipated by the diode, asTerminalJack505 suggests."
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 06, 2012, 12:47:44 pm",
"content": "Assuming the capacitor and inductor are lossless (i.e., worst case), the peak current through the diode is:Imax = V * sqrt(C/L)The peak power (given the diode forward drop is Vf) is:Pmax = Imax * Vfand the total energy per pulse absorbed by the diode is:Qd = 0.5 * C * V^2And the decay time of the field is:t_decay = sqrt(L*C) * V/Vf"
}
] |
2025-10-17T20:34:47.996745
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(-switching-5v-on-off-with-3-3v-command-)/
|
[ switching 5v on off with 3.3v command ] - Page 1
|
[
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 09, 2013, 06:18:04 pm",
"content": "Hi,I need to switch on off a 5v source using 3.3v command (ARM MCU GPIOs).The load can draw up to 2A, typically 500mA. In this application, frequency andrising times can be omit (the source is switched on or off by a human).One constraint is that the analog switch must be in serie between the sourceand the load (high side design).I planed to use a P channel MOSFET, but looking at various datasheets showtypical Vgs threshold voltages in [2 - 4]v. 2v is too close, as 5v - 3.3v = 1.7v, andI am looking for a Vgs threshold more in the [3.5 - 4]v range, or some dedicatedIC that specifically fits this purpose ... Have you any reference?Currently, what I do is to use a N channel MOSFET to convert the [0 - 3.3v] to[5v - 0v] and use it to control the second P channel MOSFET. But it makes 2FETs.Thanks for your help!"
},
{
"post_id": "",
"author": "jmole",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "June 09, 2013, 06:21:03 pm",
"content": "Why not use a low-side switch?"
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 09, 2013, 06:22:56 pm",
"content": "Quote from: texane on June 09, 2013, 06:18:04 pmOh no, two FETs!Sounds like a perfectly acceptable solution to me. Why would you rather use a dedicated IC than two cheap-ass FETs?Quote from: jmole on June 09, 2013, 06:21:03 pmI second this, though. Are yousureit has to be high-side?"
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 09, 2013, 06:34:43 pm",
"content": "Hi,Thanks for your replies.Being high side is a requirement in this circuit. I thought some specializedand low cost ICs did exist for this kind of application, but the 2 FETs solutionis fine too."
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 09, 2013, 06:40:18 pm",
"content": "I'm sure there are specialized ICs for this, but it's hard to beat the price of a little FET. Out of curiosity, why high side?"
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 09, 2013, 06:54:44 pm",
"content": "This is part of the specs: currents not returning to the ground mustalso be switched off. That is why the switch is high side."
},
{
"post_id": "",
"author": "David_AVD",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 09, 2013, 09:45:26 pm",
"content": "You could also check out some of the \"load switch\" ICs that are around. Some of them should be in the current range you want."
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 10, 2013, 05:43:03 am",
"content": "Thanks for the tip, it helps a lot. The ICs I see all have a voltage drop betweenthe gate and source of max. 0.2V ... it can be an issue."
},
{
"post_id": "",
"author": "AndyC_772",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 10, 2013, 06:07:00 am",
"content": "Is the pin of your MCU 5V tolerant? If so, perhaps you could pull it up to 5V with a resistor, connect it to the gate of your P-FET, and program the pin into open drain mode."
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 10, 2013, 06:33:10 am",
"content": "Thanks for the advice. I will have a look at the datasheet to see if GPIOs are 5v tolerants."
}
] |
2025-10-17T20:21:21.725273
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(-ttl-output-to-cmos-input-)/
|
[ ttl output to cmos input ] - Page 1
|
[
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 14, 2009, 01:42:03 pm",
"content": "Hi,I am to interface an old TTL based device withthe PIC18f. The device has roughly 20 pins comingfrom TTL based gates I have to read at a given time.I did not know, but reading the PIC18f specs, someof the GPIOs are CMOS Schmitt trigger input buffer indigital IO mode. So I guess I have to translate the level,from TTL to CMOS, because the TTL level may be toolow for the CMOS Schmitt trigger to switch correctly, Iam right?In that case, do you know about a chip doing so?Cheers,Fabien."
},
{
"post_id": "",
"author": "jimmc",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 14, 2009, 03:50:02 pm",
"content": "A pull-up resistor from the TTL output to VCCwill ensure that VOHis CMOS compatible.Value is not critical, say 4k7 lower for high speed operation. Minimum value is set by IOLmax of TTL device.For ultimate speed use 74ACT series device (eg 74ACT04 hex inverter) as a level shifter, the ACTseries has TTL compatible input thresholds.Jim"
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 14, 2009, 05:52:58 pm",
"content": "Hi,Thanks for replying. I do not really care aboutspeed in this application. I did see the trick ofadding a pullup resistor, but I do not understandit... I understand what a pullup resistor is I mean,but could you explain why it raises the voltagein this case? I mean 2 voltages from differentsnodes do not add...Thanks for helping,Fabien."
},
{
"post_id": "",
"author": "septer012",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 14, 2009, 06:06:20 pm",
"content": "Maybe you need something like this?!http://www.sparkfun.com/commerce/product_info.php?products_id=8745I used one for a 3.3v GPS to 5v PIC/Shmidt Trigger Input"
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 14, 2009, 07:07:05 pm",
"content": "Thanks, I will have a look. At a first glanceit seems a bit undersized since I would needat least 6 pins, thus an octal buffer converter.Cheers,fabien."
},
{
"post_id": "",
"author": "jimmc",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 14, 2009, 07:09:49 pm",
"content": "The standard TTL output stage is the 'Totem pole' shown here:http://www.siliconfareast.com/ttl.htmas you can see that, on its own, the output cannot rise above 2 diode drops below VCC.Adding the pull-up resistor enables the output to rise to VCCwhen the lower transistor (T4) is off.Under these conditions the diode is reverse biased and T3 has no effect.If you're not interested in speed the a higher value resistor may be used for the pull-up, it only has to overcome leakage in the TTL output stage, 22k will still give 4v with almost 50uA of leakage.I am assuming that you are running the PIC from the 5v, the TTL only operates at 5v.A quick Google on 'TTL to CMOS' gives this as one of the top results:http://www.fairchildsemi.com/an/AN/AN-314.pdfJim"
}
] |
2025-10-17T20:43:50.722657
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(-ucurrent-gold-2-amplifiers-question-)/
|
[ ucurrent gold 2 amplifiers question ] - Page 1
|
[
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 24, 2014, 12:42:24 pm",
"content": "Hi,I am implementing a current / voltage logger, whose design will be opensourced. The current monitoring part is similar to Dave's ucurrent golddesign. I read the initial article:http://alternatezone.com/electronics/ucurrent/uCurrentArticle.pdfThen, I read the new design here:http://www.eevblog.com/projects/ucurrent/In the new design, there are 2 amplifiers both with a gain of x10instead one with a gain of x100, as it was done in the previousdesign. Can anyone explain the reasons of doing so ?Thanks for helping !Texane."
},
{
"post_id": "",
"author": "kizzap",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 24, 2014, 01:23:52 pm",
"content": "He did a whole video on this..."
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 24, 2014, 01:37:36 pm",
"content": "Missed this video, thanks !"
}
] |
2025-10-17T20:01:50.832501
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(-window-voltage-comparator-)/
|
[ window voltage comparator ] - Page 1
|
[
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 17, 2009, 10:25:42 am",
"content": "Hi,As a beginner, I am reading the following book: practical electronicsfor inventor, from Paul Scherz.For a light sensor project, I need a window voltage comparator. I useone from the above book. I attached the schema.What should happen:Vout is +5v when 2.3v<Vin<2.7vVout is 0v otherwise.However, I get the opposite...:Vout is 0v when 2.3v<Vin<2.7vVout is 5v otherwise.I use a lm339 quad comparator, so that I actually has only onecomparator. I tested the comparator inputs/outputs independentlyto see if it works, and I get right measures. Maybe there is somethingI didnot understand regarding the above schema...Any idea?Thanks for helping,Regards,Fabien."
},
{
"post_id": "",
"author": "texane",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 17, 2009, 10:40:03 am",
"content": "I think I misunderstood something... the schemaactually works as expected, sorry for posting"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 18, 2009, 08:41:46 pm",
"content": "if you get a similar situation again (thats if it really happens) reverse the inputs on the comparators"
}
] |
2025-10-17T20:43:51.840836
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(3x-5y)dx-(xy)-dy-0/
|
(3x-5y)dx + (x+y) dy = 0 - Page 1
|
[
{
"post_id": "",
"author": "J4e8a16n",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 30, 2015, 04:18:57 pm",
"content": "Hi,(3x-5y)dx + (x+y) dy = 0dy/dx = (5y-3x)/ (x+y)(5y-3x)/ (x+y) = 5A/ (x+y) - 3B/ (x+y)5y-3x = 5A - 3B5y-5A = 3x - 3B5(y-A) = 3(x-B)(y-A) * 5/3= x-B...............https://www.eevblog.com/forum/Smileys/default/huh.gifHave a good day,JPDaviau"
},
{
"post_id": "",
"author": "German_EE",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2015, 06:51:33 pm",
"content": "And the point of this math exercise is??"
},
{
"post_id": "",
"author": "J4e8a16n",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 30, 2015, 10:18:10 pm",
"content": "Is to find what type of solution exist for this equation.This is from Shepley L Ross 4th editionIntroduction to ordinary differential equations.It is not exact.I could not found an integrating factorI have tried v=y/x methodPartial fraction does not seem to workIt does not seem Bernouilli or homogenous.I am aiming to understand Laplace Transform.I do it for my pleasure and the pleasure to calculate my circuits.Maybe it is crasy but I am doing it for tree years now. I started with trigonometry. It is good for the mind.Well, that's it.JPDaviau"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2015, 10:29:14 pm",
"content": "Quote from: German_EE on July 30, 2015, 06:51:33 pmwasting your time and mine... in one possibility... y=A, x=B..."
},
{
"post_id": "",
"author": "onlooker",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 30, 2015, 11:26:19 pm",
"content": "A thing having no purpose may still have solutions,(y-3x)2= C(y-x)"
},
{
"post_id": "",
"author": "Christe4nM",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 31, 2015, 10:44:25 am",
"content": "It's a differential equation. Write it in the form of dy/dx + y = x. Then solve like a first orderlineardifferential equation.Edit: tried to rewrite and solve it, but it's a non-linear differential equation. My abilities unfortunately only include linear ones with constant coefficients"
},
{
"post_id": "",
"author": "Jope",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 31, 2015, 11:09:56 am",
"content": "Solution by Wolfram Alpha:(3x-5y)dx + (x+y) dy = 0."
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2015, 05:46:23 pm",
"content": "Quote from: J4e8a16n on July 30, 2015, 10:18:10 pmAccording to Wolfram Alpha that method leads to a solution (i.e. let y(x) = x v(x) and proceed from there). However, the solution does not come out as anything simple."
},
{
"post_id": "",
"author": "J4e8a16n",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "August 01, 2015, 09:38:05 pm",
"content": "dy/dx = (5y-3x / x + y) / x = > -3 + 5y/x / 1+ y/xy/x = v y = vx ==>d y /dx = d vx/dx ==>v + v' x ==> v + x*dv/dx-----v + x* dv/dx = -3 + 5y/x / 1+ y/x ==>x dv/dx = -v^2+4v -3/ 1+vdx/x = 1+v / -v^2 +4v -3 dvfrom here complete the square?I am working at it)JPD"
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2015, 10:22:11 pm",
"content": "Something like this, I believe:"
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2015, 10:43:46 pm",
"content": "Quote from: J4e8a16n on July 30, 2015, 10:18:10 pmi use this :"
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2015, 10:44:55 pm",
"content": "Laplace Transformations are for beginners. Real men use a Widlar Transformations."
},
{
"post_id": "",
"author": "J4e8a16n",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "August 01, 2015, 11:12:57 pm",
"content": "Quote from: IanB on August 01, 2015, 10:22:11 pmYes."
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2015, 11:14:33 pm",
"content": "Quote from: J4e8a16n on August 01, 2015, 09:38:05 pmIt looks like you got it right up that point. You might notice that ( - v^2 + 4v - 3) can be factorized..."
},
{
"post_id": "",
"author": "J4e8a16n",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "August 01, 2015, 11:18:04 pm",
"content": "Thanks for your support)JPD"
}
] |
2025-10-17T19:36:21.847001
| 15
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(almost)-silent-micro-switches/
|
(almost) silent micro switches - what brands? - Page 1
|
[
{
"post_id": "",
"author": "arekm",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "November 09, 2013, 11:02:14 pm",
"content": "Are there any brands of silent (or close to silent) micro switches? The typical ones are very loud and thus aren't good candidates for mouse-like equipment.Micro switch type I'm looking for"
},
{
"post_id": "",
"author": "ConKbot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2013, 12:12:46 am",
"content": "Those are generally called \"Tatctile switches\" because they are (almost) silent, just mainly felt when you push the button. Almost any tactile switch you can get from farnell or ebay in that form factor would be near silentMicroswitches on the other hand are louder, though my mouse has microswitches instead of tactile switches, but it does make a nice audible click as you push the button."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "November 10, 2013, 12:29:03 am",
"content": "Tact switches like on the picture are very bad idea for \"mouse like applicatoans\" as they work not so stable as should, have short life and overall feeling while pushing them won't be good. Only right choice is proper microswitches like thosehttp://www.ebay.com/itm/2Pcs-Micro-Switch-OMRON-D2FC-F-7N-10M-For-Mouse-New-/251336866229?pt=LH_DefaultDomain_0&hash=item3a84d839b5"
},
{
"post_id": "",
"author": "arekm",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "November 10, 2013, 08:24:09 am",
"content": "It needs to be the same type as shown on the photo, so that omron won't fit.Googling for tactile switches then -- found Omron B3F-1002"
},
{
"post_id": "",
"author": "G7PSK",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2013, 09:28:08 am",
"content": "My Hama twister mouse has just died as well due to the use of tact switches but as it was 7 years old I wont hold a grudge against it, the tact switches were not of the usual type either so I could not find replacements. Just ordered anothe wireless mouse meanwhile I have to put up with a rat that I keep just in case."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2013, 10:02:56 am",
"content": "Grab those out of an old cheap mouse, you will probably find one that has the right switches if you look through a pile of them in a ewaste pile."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "November 10, 2013, 02:45:30 pm",
"content": "Quote from: arekm on November 10, 2013, 08:24:09 amI have some B3F-1050 which are same as B3F-1000 just taller. Seem to be quieter that average. And they are with lowest operating force (0,98N) in B3F series. B3F-1002 is 1.47N however. Take in account that lower force switches have longer life than high force ones. B3F-1000 has 1 000 000 operations durability, while B3F-1002 only 300 000"
},
{
"post_id": "",
"author": "Stonent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2013, 03:55:27 am",
"content": "I prefer the click. But that's just me. I used to use a Model M keyboard for a little while at one job. I loved it."
},
{
"post_id": "",
"author": "Tube_Dude",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 12, 2013, 05:32:02 am",
"content": "Anyone knows where I can find this type of switch, but normaly closed. Means, it opens when pressed."
}
] |
2025-10-17T20:13:19.920849
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(almost)-zero-miliamps-on-the-power-supply-display-with-no-load-connected/
|
(Almost) zero miliamps on the power supply display with no load connected - Page 1
|
[
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 01, 2024, 11:39:04 am",
"content": "Hi!I have recently been wondering about the methodology of measuring current in power supplies, which shows the current drawn from them with an accuracy of 1 mA. (I have one similar to the one below).https://www.amazon.com/Adjustable-Switching-Regulated-Interface-Adjustments/dp/B09XTWKVLD/ref=sr_1_21?crid=UBUETUWMHPLS&keywords=bench+power+supply+5A&qid=1706787155&sprefix=bench+power+supply+5a%2Caps%2C205&sr=8-21I noticed that when I do not connect any load to this power supply, after pressing OUTPUT it should simply display 0.000A, but it displays once 0.000A and once 0.005A. When I connect a resistor to the power supply outputs, 5mA is always added to the current measured by the power supply.So, for example, when I connect a 1kohm resistor and set it to 5V, I see 0.010A instead of 0.005A, etc.Is this behavior of the power supply normal or some hidden fault?"
},
{
"post_id": "",
"author": "inse",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 12:07:59 pm",
"content": "Don’t confuse accuracy with resolution"
},
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 01, 2024, 12:13:40 pm",
"content": "Perhaps this was the impression, but the very fact of the existence of non-zero current despite the lack of load connection worried me."
},
{
"post_id": "",
"author": "inse",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 12:17:10 pm",
"content": "Perhaps there is some kind of discharge resistor across the output clamps"
},
{
"post_id": "",
"author": "Buriedcode",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 12:19:06 pm",
"content": "Quote from: bodzio_stawski on February 01, 2024, 12:13:40 pmYou mean non-zerodisplayedcurrent. You are assuming the power supply (and the display) is measuring the output current perfectly - it isn't. There will be errors, including offsets, which in this case appears to be around 2.5mA - and if the resolution of the measurement is 5mA, then it will toggle between the two nearest values - 0.000 and 0.005.If it always adds 5mA to the diplsay, then the offset iwth +5mA, or + 0.005A. Some instruments allow calibration against a known reference, so you can zero these offsets out."
},
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 01, 2024, 12:39:23 pm",
"content": "The port can show 0.005, 0.006, 0.007 depending on the load, so it's not about resolution. To make matters worse, what is displayed depends on the voltage set. At 5V the current still fluctuates between 0 and 0.005A, while at e.g. 20V it is permanently 0.005A. However, when you wait a few minutes or more, the value fluctuates between 0.005 and 0.000, pointing often to 0.000, and finally stops at 0.000. PolskiBut when you then turn the power off and on again, those few milliamps will show up on the display again without any load connected.Unfortunately, it is not possible to calibrate the power supply (at least without intervening inside the device)."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 01:48:03 pm",
"content": "1% accuracy is hard to achieve with the best off the shelf parts. You'll see boasty specs for precision current sense amplifiers. That's all well and good but the typical external shunt resistor will add a nasty temcpco of 0.39%/'C. If you go from +25 to +50 you'll expeience 10% drift, ouch.There are devices with integrated shunts with a much better tempco they tend to be aimed at high current measurement. eg The INA250 looks like good choice for lower currents. One day I'll read the datasheet."
},
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 01, 2024, 02:14:41 pm",
"content": "Quote from: Terry Bites on February 01, 2024, 01:48:03 pmWell, it's true, I don't expect super accuracy from a somewhat unknown device. However, I am curious how the power supply's own ammeter can measure any self-current when there is no load. I wonder what is a source of that effect on display. I admit that I approached this matter somewhat in the way that the \"lack of an electrical quantity\" cannot generate any value error. Do other brands of laboratory power supplies have similar currents?"
},
{
"post_id": "",
"author": "BeBuLamar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 02:31:04 pm",
"content": "The specs said that current display accuracy is +/- 0.5% +5 digit. The fact that it has the +5 digit if it displays 5 cound more or less it's in specs. You shouldn't expect too much accuracy."
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 04:21:23 pm",
"content": "Quote from: bodzio_stawski on February 01, 2024, 02:14:41 pmCurrent is usually measured by using a shunt, aka current sense resistor. When current flows, there is a voltage drop. That voltage is what is measured. Lab power supply must be able to measure ralatively big range of current, from milliamps to amps. The sense resistor must be low value, to not heat up too much at high currents. Lets say it is 50 milliohms. But then low currents are difficult to measure. At 1mA you get voltage drop of only 50 microvolts! You ask, how can anything at all come out of nothing at zero current? We are dealing here with very low voltages, we need amplifier. Any amplifier will have offset and gain errors. Plus there could be other issues, like ground potential shifts in the circuit board. Current sense resistor is usually measured by using differential amplifier and ground shifts should not affect measurement - theoretically. But the measured voltage likely does not go as differential signal all the way to ADC, so ground shifts might still affect it. And yes, there are ADC errors too. There is also noise. Long story short, it is not easy to achieve microvolt precision. When there is no signal present, what is still present are errors and noise, there is no way to fully avoid that."
},
{
"post_id": "",
"author": "MarkT",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 08:11:50 pm",
"content": "Suspect they just fake any reading below 0.005 to 0 to hide the offset error (which would be more annoying in most situations)."
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 08:24:03 pm",
"content": "Quote from: bodzio_stawski on February 01, 2024, 02:14:41 pmThere are scaling errors, linearity errors and nulling (zero) errors. They all have their various causes, but there's nothing unusual in having some noise or fluctuations at the zero point any more than there would be having the same noise or fluctuations at some other point. Its a universal issue with almost all types of meters. It's not the \"electrical quantity\" or lack thereof, it's the meter itself that generates the error."
},
{
"post_id": "",
"author": "SiliconWizard",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 01, 2024, 08:30:57 pm",
"content": "From your description, the current reading would appear to have 5mA resolution, so what you see is, unfortunately, normal. Yes, say the current measurement is done with a 10-bit resolution, if say the current range is up to 5A, there that's your about 5mA resolution. Nothing you can do about it, and not a sign of defect as long as it was documented in the power supply's specs. But don't expect neither good resolution nor good accuracy with these power supplies. The reading is just meant to give you a rough idea. If you need better, use a multimeter."
}
] |
2025-10-17T16:41:19.997882
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(analog-electronics)-capacitor-measurement-circuit/
|
[Analog Electronics] Capacitor Measurement circuit - Page 1
|
[
{
"post_id": "",
"author": "Belquay Neust",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 04, 2020, 12:50:56 pm",
"content": "Hello!I want to build a circuit that can measure a capacitor. In that case I have used a REF102 and LM358 as (as much as it possible) precision current source. I want to measure between for example 1nF to 10uF. I want to make it as simple as it possible, and for now I want to receive a linear load voltage on capacitor, but I am receiving a exponential slope with a knee over 63%. What can I do to make it more linear?"
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2020, 01:36:00 pm",
"content": "If you charge/discharge a capacitor with a constant current you will get a constant slope ramp. So I'm assuming you are measuring the time to go between two voltages?What voltage is V+? Which voltage does the 63% relate to?"
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2020, 01:44:00 pm",
"content": "Quote from: Belquay Neust on March 04, 2020, 12:50:56 pmWhat are you using for V+ of the REF102?As the capacitor charges up, you are probably losing headroom for the REF102, so it is no longer regulating."
},
{
"post_id": "",
"author": "Belquay Neust",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 04, 2020, 02:29:03 pm",
"content": "You are talking about Quiescent Current, but I am talking about current from OP AMP, that I have in my circuit. From this datasheet is completely possible to make 1uA current source, but I can't get a constant slope ramp with about 8uA from LM358.On REF102 I have +5V.It is reacting like I would connect a capacitor to 500k resistor and 10V. Or maybe someone have a hint how should I build a stable current source for capacitor measurement if I am wrong with REF102?"
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2020, 02:36:08 pm",
"content": "Quote from: Belquay Neust on March 04, 2020, 02:29:03 pmAt T=0, 5 volts on pin 2, 0 volts on pin 4, 10 volts on pin 6? Nope"
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2020, 02:48:19 pm",
"content": "Analog computers make a stable slope all the time, it's all part of that integration thing.Consider an op amp configured with dual 15V supplies (for now), a 1 ufd capacitor in the feedback path instead of a gain resistor and a 1 Mohm resistor to the inverting input. Ground the non-inverting input.Start with the input to the 1 Mohm resistor equal to 0V. Now set the input voltage to +10V. Exactly 1 second later, the op amp output will be -10V and the ramp down will have been linear. That's because Tau (=R*C) is 1 second (10-6Farads * 10+6Ohms => Tau = 1 second)https://www.electronics-tutorials.ws/opamp/opamp_6.htmlThere are other ways to make a linear capacitor charge circuit but this is the one I am familiar with. I like analog computing!You don't need a linear charge voltage, all you need to do is change the voltage (as a % of operating voltage) over some period of time and then fit the time and voltages into the charge equation.Vout= Vin* (1-e-t/Tau) + V0So, the initial voltage goes into V0and is usually 0V, Tau is what you're trying to determine because you get Tau = R*C and you know R. Vin, Vout and t. A little ugly arithmetic and you're there.https://www.picotech.com/library/experiment/capacitorYou know that in 1 Tau seconds, the capacitor will charge to 63% of the input voltage, starting from zero. Substitute t = Tau in the equation above and you get Vout= Vin* (1-e-1) + V0with V0= 0. This results in 0.632 or 63.2% of the input voltage in 1 time constant.I have attached a charge plot where I am hitting the capacitor with a square wave.The Internet is full of capacitor measuring projects, try Google."
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2020, 02:48:46 pm",
"content": "REF102 minimum voltage is 11.4V, with your design you'll need at least 15V."
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2020, 05:17:28 pm",
"content": "I have built a capacitor tester using the method described by rstofer. I used an arduino. It worked well.I can understand the desire to use a constant current even though it is not necessary."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2020, 06:38:58 pm",
"content": "Quote from: Wimberleytech on March 04, 2020, 05:17:28 pmUsing an Arduino allows for automated selection of charging resistors.Here is the Digilent Impedance Analyzer for the Analog Discovery 2 (a very cool gadget)https://store.digilentinc.com/impedance-analyzer-for-analog-discovery/If you skip down the page, on the right, there is a link to the schematic and you can see where relays are used to select decade values of resistors (upper right of schematic).https://reference.digilentinc.com/_media/reference/instrumentation/analog_discovery_impedance_analyzer_sch.pdfBy using small relays, they get away from the issues related to driving MOSFETs as well as having to account for voltage drop across the MOSFET. Pretty clever!I could see doing something similar with an Arduino but like everything else related to Arduino applications, it has already been done and the project is on the Internet:https://www.arduino.cc/en/Tutorial/CapacitanceMeterGoogle for 'Arduino capacitor tester' without the quotes"
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2020, 06:58:52 pm",
"content": "Quote from: rstofer on March 04, 2020, 06:38:58 pmThat is what I did. Two values. Should have been more to handle a wider range of caps. This effort was a teaching exercise. I gave the problem to a kid I was teaching electronics and programming. Every exercise I gave him, I had to solve myself.When switching resistors, I set one (port) as output and tristated the others. Lived with whatever VDS there was associated with the output drivers.This was a great project for the kid because lots of different things can be learned."
},
{
"post_id": "",
"author": "Belquay Neust",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 06, 2020, 08:55:54 am",
"content": "Ok, I have changed my voltage to +15V and -5V. I've got a little better results, but still it's impossible to measure 10nF. I do not want to use arduino, because my project is on STM32F103VC, but I don't want to fixing measurement in firmware, because I do not believe that resolution of ADC should work correctly. Now I have:for 10nFfor 2uF"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 06, 2020, 11:35:06 am",
"content": "If you want to measure the capacitance, there are easier ways to do it. How about a simple Schmitt trigger oscillator? The output frequency is inversely proportional to the capacitance. Use a low a comparator with a push-pull output stage, such as the MCP6561 or TLC3702 to make life easier.If the correct values of R1, R2 & R4 are selected, then F = 1/(RC), to within 1% and even rounding R4 to 150k will give a closer tolerance, than most capacitors."
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 06, 2020, 12:20:52 pm",
"content": "Quote from: Belquay Neust on March 06, 2020, 08:55:54 amIf you are using the diagram in post#1 with V+ now +15V, you will only get a reliable reading up to 15-11.4V=3.6V or thereabouts. Read the REF102 datasheet.Probably wise to post more details about the exact setup you are using, ADC sample rate, desired accuracy, schematic etc.."
},
{
"post_id": "",
"author": "Belquay Neust",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 06, 2020, 02:12:55 pm",
"content": "I have solved my problem by Instrumentation AMP, no Arduino and no comparators. On my output i have 7.8 uA and linear response. Now I can easily calculate this by firmware. Ok, now I will go on. Thanks for your good faith and fast reaction."
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 06, 2020, 02:17:11 pm",
"content": "Quote from: Belquay Neust on March 06, 2020, 08:55:54 amYou are still not giving enough headroom to the REF block. I think you need to change your architecture.Maybe something like this. Get a matched pair for the PNPs but you can test the concept with discretes."
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 06, 2020, 04:23:58 pm",
"content": "Quote from: Belquay Neust on March 06, 2020, 02:12:55 pmI still don't think you are understanding the limitation with the REF102 V+ rail.All you've done is added a $5 amplfier with a gain of 3.Apart from the gain of 3, this really gives you nothing extra over the reading the OUT on the LM358."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 08, 2020, 07:07:19 pm",
"content": "Quote from: fcb on March 06, 2020, 04:23:58 pmYes, the same result can be achieved by using the other half of the LM358, as a non-inverting amplifier with a gain of 3."
}
] |
2025-10-17T17:54:25.509098
| 17
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(another)-isolation-question/
|
(Another?) Isolation question.... - Page 1
|
[
{
"post_id": "",
"author": "MartolFart",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 08, 2020, 04:25:06 pm",
"content": "Hi,I have a USB scope I've been using for SMPS troubleshooting from a desktop PC.... I'm switching (no pun!) to using a laptop and was planning to run from battery to facilitate probing across front end components which I'm thinking is safe (assuming normal HV precautions). But were I to accidentally leave the laptop connected to the charger, I'm thinking it would not be an issue either? The charging adapter plug in is not polarized with no ground prong. There is no continuity from prongs to tip connectors. Thoughts? Thanks!"
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2020, 05:43:03 pm",
"content": "Yes. You'll end up killing yourself.Donotisolate the test equipment,isolate the device under test(DUT).This means: get hold of a mains isolation transformer."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2020, 05:58:13 pm",
"content": "This comes under the general category of 'Floating a Scope not designed or intended for floating use'. Good engineers have been killed doing that - it only takes ONE small mistake to electrocute you. Differential HV probes rated for CAT II usage aren't *that* expensive nowadays so there should be no need, or excuse, for floating a scope.The *ONLY* way I'd ever consider floating a laptop is if it (and all connected instrument pods etc.) are *TOTALLY* inaccessible behind a perspex safety screen, its on battery power with no PSU connected, any need for the user to control it is handled with awirelesskeyboard and/or mouse, and probes are only connected/disconnected from the D.U.T. with its mains power disconnected and its reservoir capacitor discharged (i.e. absolutely *NO* hand-held probing).Don't trust the 'isolation' provided by a non-grounded laptop PSU. It will have a relatively high capacitance between input and output, and may well suffer insulation breakdown if stressed by high frequency high voltage switching waveforms as are common in SMPSes, power inverters, VFDs etc."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2020, 07:34:27 pm",
"content": "Quote from: MartolFart on July 08, 2020, 04:25:06 pmInternally the charger has a transformer which provides galvanic isolation between the input and output. However it was designed for and operates with a minimum common mode input to output voltage and they are typically only rated for continuous operation to a fraction of their input voltage between the primary and secondary.In theory if you want to do this, then an isolation transformer would allow it however as others have already said, this is a hazardous mode of operation and is not recommended."
},
{
"post_id": "",
"author": "Purduephotog",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 02:24:10 am",
"content": "I was working under a desk in Germany at an AFB. They run on 220. Well... someone dropped a neutral- so I took 110V or 220V across the chest... by touching the USB port on one computer and the Serial port on another computer.So don't float it. It hurts....there was a MASSIVE writeup over the incident, as you'd expect. That could very well have killed me given where and when I was working."
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 07:06:43 am",
"content": "Quote from: MartolFart on July 08, 2020, 04:25:06 pmYes, the problem is that when you connect unisolated test equipment to an HV circuit, all normal HV precautions also apply to the test equipment now.And if you further have a laptop connected to that scope, ..."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 10:47:49 am",
"content": "Quote from: blueskull on July 09, 2020, 07:20:30 amIf the scope is correctly earthed (as it should be), the GFCI will work perfectly."
},
{
"post_id": "",
"author": "capt bullshot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 10:59:00 am",
"content": "Apart from the plentyfully mentioned personal safety issues, measuring live SMPS components the way you mentioned might disturb or damage your equipment due to high frequency and high voltage common mode signals. Better do not measure switching nodes or nodes significantly affected by the primary switching action with any kind of floated scope, except it is specially made for this purpose (e.g. the TPS20xx, or some of the stuff from Cleverscopes). If not for your personal safety, for the sake of your equipment."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 04:27:04 pm",
"content": "Quote from: blueskull on July 09, 2020, 11:03:14 amWhether you simultaneously touch L and N on the \"live\" side or the \"floated\" side of the isolation transformer makes no difference, neither will trigger the GFCI and you'll be just as dead.The point is that having 'scope/laptop at live potential is lethal, having them at earth potential is safe (apart from the fact that you're working with 230 VAC, of course)."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 05:34:04 pm",
"content": "Anyone who doesn't believe that an isolating transformer prevents GFCI (RCD) protection devices from working should consider the following facts:GFCIs detect faults by detecting current imbalance between Line and Neutral.Neglecting capacitive leakage and non-ideal insulation, by Kirchoff's current law, the current entering any two terminal transformer winding at one terminal must be identical to that leaving it at the other (as any point in the winding may be considered a KCL node).Capacitive leakage in a line frequency mains transformer will be far less than even the most sensitive GFCI's trip threshold current.Therefore it is impossible for a GFCI with either its supply or load terminals directly and only connected to a two terminal transformer winding to trip, unless the circuit insulation or transformer insulation is defective.To add ground fault detection after an isolating transformer with a floating secondary would require sensing the ground conductor current of all test equipment that may introduce a ground to the D.U.T. and wouldn't protect you if you made contact with a live part of the D.U.T and a grounded test equipment chassis on the load side of the ground current sensing point. It would also be defeated if anything introduced a parallel ground path that did not pass through the ground current sensor. Unfortunately ground conductor current sensing circuit breakers are no longer readily available."
},
{
"post_id": "",
"author": "calzap",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 06:37:36 pm",
"content": "If you are touching the scope probe or attaching the ground clip to an non-isolated DUT, there is the chance than any piece of metal on the computer (case, latch, hinges, connectors, etc.) and anything attached to it might be hot relative to ground or a neutral. Say it's the hinges. If you are grounded and touch them, it could be the last thing you touch.It you are using an isolation transformer for the DUT, use a multimeter to check that it's really isolated before proceeding with tests. Some transformers that are sold with an isolation label are not really isolated from ground. They are designed to protect equipment from line noise and surges. Read the fine print; use a multimeter to check.Mike in California"
},
{
"post_id": "",
"author": "MartolFart",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 17, 2020, 07:20:49 am",
"content": "Thanks to everyone for their comments, concerns and recommendations! Back at it after some domestic distractions!In summary, ideally I'd have the isolation auto transformer and purpose built differential probe.... When I was in production doing this kind of work frequently I would already have or track down these goodies (usually). But us old dabblers just wanna have some fun without expending a ton of funds! I did take a look at differential probes and didn't see much under $200 (and none too impressive really), maybe I'm missing the deals to be found? Pretty sure I don't need the 10kV 10GHz jobs....So anyway, I'm doing the two 100x probe (ground leads removed) A-B approach, and based on the sage advice rendered, won't (intentionally) test with the laptop on its charger.Another idea I had for isolation work around is to use a disconnected from mains UPS to power the DUT for quick tests (under light load and using the light bulb current limiting gimmick)?Btw I am definitely an adherent of the one hand behind my back HV testing technique (if I can't just hang a probe somehow) and I don't do it enough to get complacent (which is probably the biggest risk right along with faulty design and implementation issues) which is how I've earned my moniker I imagine! I should be okay unless I fall off a ladder...."
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 17, 2020, 08:31:19 am",
"content": "If you use standard passive probes without ground leads then you can ground the scope without issues.Moreover, you probably should, in case one of the probes arbitrarily decides to short out. If the scope is grounded, there will be a bang, smoke and tripped circuit breaker. If it's floating, there will be a surprise HV on the scope.editHonestly, I were to float a scope I would rather connect it to the hot ground, which is the only point of reference that I have ever cared about in an SMPS. That way at least Iknowthe scope is live, stand back and don't touch it. Not sure if you should be doing it, though, given the sort of questions you askQuote from: MartolFart on July 17, 2020, 07:20:49 amNo such thing, it's either auto or isolation."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 05, 2020, 10:31:57 pm",
"content": "A related thing to watch out for:If you have a metal-cased computer (or other equipment), and the PE (3rd prong) wire is not connected properly, then the two capacitors in the line filter will pull the metal case to half of the mains voltage, in series with a reasonable but not trivial capacitance. The capacitor should be chosen such that 60 V or 110 V (depending on the local mains) should not electrocute a healthy person, but you can easily receive a jolt that could knock you off a ladder or other slapstick cause of injury, especially in 220 V lands. At work, we called this the \"Dan effect\", as in \"it's not easy to shock Dan, but...\" after he encountered this phenomenon in the field, where the locals had not bothered to ground the generator properly."
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 05, 2020, 11:16:10 pm",
"content": "Quote from: MartolFart on July 08, 2020, 04:25:06 pmIs your USB scope rated for those voltages and CAT II?As for relying on your charging adapter for ground isolation, it may be adequate to keep 120VAC 60HZ at bay, but depending on how you connect everything up, you could be exposing it to something like 400V and 50kHz. It won't do well at that. And even before it goes up in smoke, you may have a highly energized laptop. Make sure your files are backed up and your will is current."
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 05, 2020, 11:18:36 pm",
"content": "Quote from: magic on July 17, 2020, 08:31:19 amHe's referring to a combination unit with both in one box, typically autotransformer first and isolation transformer second."
},
{
"post_id": "",
"author": "MartolFart",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 06, 2020, 11:33:44 pm",
"content": "Thanks for the comments!My pure chinesium USB scope has no stinking IEC 1010 category labeling... It does proudly sport the CE insignia (self tested to the highest standards!). The max input with 1x probe is 35V. The 100X probes don't have cat specs either, just 2KV DC+AC again with CE label.Per my previous post, I'd already discarded the idea of leaving the charger on the laptop powering the USB scopage gizmo; may as well just run off the battery anyway. I really don't think it was a ridiculously stupid question or idea though.... I didn't see any responses to the other idea of running the DUT off a disconnected from mains UPS? As I mentioned before, if I was doing this kind of work frequently/for a living, I'd prolly break down and buy an isolation transformer, maybe even a fancy one with integrated rheostat...So another question comes to mind as a result of the test eq cat rating.... If the DUT is powered by \"protected electronic equipment\", does CAT I suffice?My reading on the IEC category ratings indicated these were developed to address transient and available energy (essentially short circuit current) as adjunct to the insulation voltage ratings already commonly specified..... My ancient Fluke DMM has no labelling on the leads with max 1000VDC/750AC on the input jack and certainly no CAT rating!Not having much luck with the SMPS PD so far (I did fix two other smaller ones!), I might have to beg some help when I get data collected, trying to sketch out the discrete chopper schematic is killing my old eyes....)!"
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 08, 2020, 05:19:20 am",
"content": "Quote from: TimFox on September 05, 2020, 10:31:57 pmI will add yet another: 3 phase motors with the chassis miswired to line"
}
] |
2025-10-17T17:42:53.315625
| 18
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(another)-pulse-generator-with-si5351/
|
(another) Pulse generator with Si5351 - Page 1
|
[
{
"post_id": "",
"author": "stcoso",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 20, 2020, 11:03:09 am",
"content": "Hi! I'm trying to design a pulse generator.I need adjustable 1-10 ns pulse with adjustable frequency (ideally 10kHz/50MHz).Si5351 has 3/8 clock outputs with adjustable 333ps/step phase offset. So I'm thinking to generate 2 clock signal ( same frequency but out of phase) and feed them into a fast comparator (with reasonable rise/fall) to obtain the pulse that I need.Where am I wrong?"
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 20, 2020, 03:25:33 pm",
"content": "si5351 already has 1 ns rise/fall time. So, there is no need for comparator, you can use it's output directly."
},
{
"post_id": "",
"author": "stcoso",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 20, 2020, 03:31:50 pm",
"content": "Ok... but it's 1ns 20/80% and that wouldn't allow 1ns pulse width"
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2020, 09:43:50 am",
"content": "Quote from: stcoso on February 20, 2020, 03:31:50 pm1 ns pulse width is 500 MHz. But you're mention that you're needs 10kHz...50MHz frequency with 1..10 ns rise time. si5351 allows to produce 5 kHz...200 MHz with rise time 1 ns. Which ideally fits your requirements, isn't it?"
},
{
"post_id": "",
"author": "stcoso",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 21, 2020, 12:18:41 pm",
"content": "1 to 10 ns pulse width. Rise/fall need to be good enough to get 1ns pulse with decent shape (this signal will be fed into a gan driver). For a 1-ns pulse width 1ns rise/fall time are clearly not enough. Also, si5351 has fixed duty cycle and is limited to 200MHz so can't use this directly to generate 1ns pulse width.I'm wondering if there is a clever way to achieve what I need.I could also use a AND gate with the clock signals from the si5351 shifted (starting from 180°) to achieve overlap."
}
] |
2025-10-17T17:55:17.257498
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(arduino-pwm-analog-meter)-my-fancy-contraption-freezes-intermittently-(/
|
[Arduino, PWM, analog meter] my fancy contraption freezes intermittently :( - Page 1
|
[
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 11, 2017, 04:58:28 pm",
"content": "Hey there enginerds!I made a fancy contraption and documented the first beta versionhere in the forum…it fails intermittently, i.e. the bloody ting doesn't twitch its needles anymore.Here is what it looks like on the back side:…directly connected, through 22k resistors.I run it on Linux. Its CH340 USB to serial IC is the only device of its kind handled by the kernel, so it's always /dev/ttyUSB0.I noticed two failure modes with varying severityttyUSB0 just disappears and my, admittedly rather crude, script throws errors. In this case i stop the script, unplug, wait a few seconds, re-plug, restart, donettyUSB0 remains existing, the RX LED of the Arduino (nano v3 clone) still indicates incoming data (changes of duty cycle), but the needles don't move anymore.In second case i made a weird observation: originally i tried to blind-fumble the reset switch on the back side, i felt the connection points under my finger tip, where i soldered the meter to the board …viola, without actually closing the reset switch, it started moving its needles again. My layman's guess is, that there is some kind of capacitive or static charge thing going on. Something that prevents the systems' desired operation, but is neutralised by connecting my body (skin) to those contacts, which causes it to operate as intended again.What phenomenon did i witness?And what does it teach me (us) regarding improvement of the system reliability?"
},
{
"post_id": "",
"author": "Nusa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 11, 2017, 05:20:09 pm",
"content": "Or you've got a poor solder joint on one of those wires, and mechanical force from your finger made it work again, at least for the moment. You could try reflowing them all and see if the problem goes away."
},
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 24, 2017, 02:06:21 am",
"content": "Quote from: Nusa on March 11, 2017, 05:20:09 pmHmm, that might actually be the cause. Well, kind of; I \"made it work again\", and left it (the whole system, metre, cables, USB connections) untouched for over a week. It still works. I doubt that a cold joint is the culprit here. All solder joints look fairly decent. Might be a broken wire though, but intensely wiggling those didn't affect operation. Another parameter I've changed is the USB port, the contraption is connected to. I'm still using that one cheap arse Chinesium USB cable, which proved unreliable when wiggled in the USB 2.0 host port of my PC. Wiggling it in an USB 3.0 port doesn't disturb operation at all. So, that USB 2.0 host port could be of lesser quality, rather than the cheap Chinesium pokey bit. Wiggling the pokey bit in the Arduinos' mini-USB receptacle, quite fiercely, didn't affect operation, at all.The mentioned unreliable USB 2.0 host port is part of the front i/o panel of a CoolerMaster Elite 130 Mini-ITX case.Initially i thought, the CH340 USB-tty-IC of the Arduino Nano v3 (clone) is unstable; it's (seemingly) not -> worked fine all the time …on the USB 3.0 port …in 2.0 mode, of course."
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 24, 2017, 06:30:41 am",
"content": "I had a similar intermittent problem with stuff I connected to the front-panel USB ports on my computer case. Finally I took it apart and looked carefully at the solder joints connecting the USB connectors (and audio, mic jacks) to the underlying PCB that mounted to the case. They were slightly cracked from the mechanical movement caused by plugging and unplugging cables from the connector. Cheap brittle lead-free solder cannae take the strain of repeated mechanical stress cycles! So I re-soldered everything with good old leaded solder and voila, no more problems.I don't know if this is happening with your case USB connectors but it might be worth taking a look."
}
] |
2025-10-17T19:00:13.126283
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(arm)-does-a-usb-device-need-a-driver-on-the-host-microcontroller-to-get-power/
|
[ARM] Does a USB device need a driver on the Host Microcontroller to get power? - Page 1
|
[
{
"post_id": "",
"author": "robotwizard",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 12, 2018, 06:39:57 pm",
"content": "I've recently transitioned from arduinoes to ARM devices[Noob Alert]. I'm trying to make a maze solving robot - 'micromouse' and I'm trying to use an optical mouse's sensors to track the movement of the robot on the maze floor.So I got this free NXP development board from Hackster - a FRDM-K82F board; This Board has USB support. So I saw the USB demo drivers and they're fairly complicated and add to that my puny knowledge of the USB stack - So I decided I would setup the hardware first; so I'm making a prototype and I connected two optical mice to a USB hub and tried connecting it to the USB port on the microcontroller via a cheap micro USB cable. Before powering the microcontroller up, I read in the documentation that there is a jumper in the FRDM-K82F that is supposed to be 'jumped' to give power to the USB port and allow the board to act as a USB hub. I connected the jumper properly.Now to check if the hardware is working properly, I connected the optical mouse + hub setup to my laptop computer and the laptop is reading both the mice. But when I connect the hub to the microcontroller and power the microcontroller, The light on the USB hub doesn't light up; neither does the light on the optical mouse.So this is my noob question - Does a USB host need to be running driver code for it to supply power to the devices? Or could there be something else wrong with my setup. Will I have to write the driver code before plugging in the optical mouse setup?Also it would be nice if someone could direct me to a nice tutorial other than the documentation on setting up USB devices on NXP or ARM cortex M4 devices.This is the link for the Development Board I have.https://www.nxp.com/products/processors-and-microcontrollers/arm-based-processors-and-mcus/kinetis-cortex-m-mcus/k-seriesperformancem4/k8x-secure/freedom-development-platform-for-kinetis-k82-k81-and-k80-mcus:FRDM-K82F?&&tab=In-Depth_TabI've also attached the Datasheet for the Board.Please tell me if you need more information. Thanks for your time!"
},
{
"post_id": "",
"author": "GeorgeOfTheJungle",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2018, 06:45:00 pm",
"content": "As far as I know a USB 1 or 2 (and 3 too?) host should provide up to 500 mA @5v even when/if there's nothing connected to the data+ and data- pins."
},
{
"post_id": "",
"author": "GeorgeOfTheJungle",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2018, 06:48:04 pm",
"content": "OTOH, it may well be that your mouse won't lit its led until after it has negotiated properly with the host, you know, the enumeration phase and all that jazz."
},
{
"post_id": "",
"author": "robotwizard",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 12, 2018, 06:49:38 pm",
"content": "Yes that is what I was wondering about."
}
] |
2025-10-17T18:40:52.874577
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(art-of-electronics)-zener-power-supply-exercice/
|
[Art of Electronics|solved] Zener power supply exercice - Page 1
|
[
{
"post_id": "",
"author": "Nicals",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 20, 2017, 04:53:41 pm",
"content": "Hello,I'm currently reading theArt of Electronicsbook, and I am having difficulties with an exercice relating to a simple zener diode regulated power supply.The exercice says this (ex 2.6, p 82, 3d edition):QuoteThis is all about resistance with a Zener diode in serie.The next exercice is the same thing, but with a transistor in emitter follower configuration to show the difference in required zener power.And then added some computation to it.We want at least 100mA load, so I just assume that I had a 100mA current sink through the right wire.I then computed the R1 resistance value so that 100mA flows through it.Code:R = Umin / Imax = 20 / 0.1 = 200Without any load connected, I still have my 100mA flowing. This is at least the 10mA asked. So we are good.At this point, I know I did something wrong. I should have computed the current through the Zener diode.But there is no indication on the Zener internal voltage.I also don't understand why we would have a Zener current of at least 10mA.What does this relates to ?Shouldn't we want the zener current to be minimized to prevent power loss ? Or is their a good reason to have a minimum current though the zener diode ?I'm really lost at this point. It seems easy, but I can't manage to find from where I should start to solve this problem.Thanks for helping."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 20, 2017, 05:13:22 pm",
"content": "The zener current keeps the diode in a mode where it regulates the voltage drop.When you calculate the resistor, you need to consider both the load current plus the zener current at the same time. You need to consider this at Vmin which you did. So, Vmin / (10 + 100) mA...When Vin is higher than Vmin, there will be more current flow through the zener and the maximum zener current will occur when there is no load and the voltage is at Vmax. Once you know the maximum zener current (based on the resistor selected above), you just multiply by the zener voltage (10V) to get the power dissipated. As a practical matter, the actual device will have a rating somewhat higher than the calculated rating."
},
{
"post_id": "",
"author": "djnz",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 21, 2017, 04:04:57 am",
"content": "If you look at a typical zener's I-V curve, for very low currents, you are still in the \"rounded\" region of the curve, but beyond a certain current, the curve becomes a more vertical straight line. Look at Fig 1.15 on page 12 of your book. For good regulation, you want to be in the stiff straight line part of the curve, not the rounded part. Mathematically, you want dV/dI to be as close to zero (the definition of regulation!) or, dI/dV to be very large in magnitude. Thus, to be safe, the authors suggest that current through the zener should not drop below 10mA.However, this 10mA is not the output current! There is some input current coming in; a portion of it goes through the zener and the rest is delivered through the load."
},
{
"post_id": "",
"author": "Nicals",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 22, 2017, 02:48:46 pm",
"content": "Thanks, it is now much more clear. It really helped me."
}
] |
2025-10-17T18:58:11.481784
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-about-minibloc-sot-227-b-mosfets-and-the-extra-source-pin/
|
[ASK] About miniBLOC SOT-227 B mosfet and the extra Source pin - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 27, 2016, 07:56:11 am",
"content": "Few questions :- The extra 2nd Source pin which is drawn near to Gate pin, does that mean or imply anything special ?- The words \"Kelvin Source (gate return) terminal\", anyone can explain in more friendly words please ? Examples maybe ?- Is that a standard mosfet's symbol ?Thanks in advance."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2016, 09:04:05 am",
"content": "Connect the gate driver to the G-S pins on one side. Connect load current to the D-S pins on the other side.This avoids load current flowing through the drive pins, improving performance.Tim"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 30, 2016, 01:23:44 pm",
"content": "Thanks for the replies guys.Quote from: T3sl4co1l on April 27, 2016, 09:04:05 amTim, what is the exact performance improvement we're talking about ? Example case ?Although its mentioned that we can use both source pins as they're identical, I assume these two has also separated bond wires into the die ?Quote from: blueskull on April 27, 2016, 09:12:02 amAs this form, the wires for either three pins will be much longer (higher parasitic inductance) than the other mosfet types that is soldered on board, as we need to use quite relative long wires to be secured at the terminals. Does this mean for this type of power mosfet, relatively high switching speed is quite challenging ?"
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 30, 2016, 01:53:30 pm",
"content": "The drain is a sheet tab from the terminal to the device top, the source is another sheet tab contacting the device inside, and it leads to both terminals using the same length of strip. This means the resistance is the lowest possible so the gate capacitance can be charged and discharged as fast as possible, without the voltage drop caused by 100A flowing in the other lead having an influence on it. Gate lead probably is a slightly narrower sheet tab, just so they can use the same compression welder settings on all 3 terminals to do the connections.Think it through, if the source lead voltage rises 1V on turn on, then the gate effective voltage drops 1V, and this can increase power dissipation a lot to the point of self destruction. Thus a lead to reduce this drop as much as possible."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2016, 03:56:00 am",
"content": "Quote from: BravoV on April 30, 2016, 01:23:44 pmIIRC, the typical lead inductance is around 8nH, and the mutual is much less.You bolt the PCB to the device(s), after bolting them to the heatsink. With several transistors, the PCB can be self supported, or you can use standoffs or brackets to hold things together as usual.Made a 5kW inverter module, some 5 years ago, using a quad of these. Up to 400kHz. Think the expected limit was around 600kHz at modest derating, but we never pushed it.Suppose you have a transistor with an equivalent gate of 2 ohms + 20nF. This must be driven at +15/0V (or some negative 'off' bias), as fast as needed (on the order of 2 ohm * 20nF = 40ns).A typical driver would be IXDD614CI, which has under 1 ohm output ESR, and can switch in about 20ns, fast enough.The gate driver loop includes these elements:- Gate drive supply bypass cap (\"big enough not to matter\" C, some ESL and ESR)- Driver IC (~10nH ESL due to pin inductance, ~1 ohm ESR due to Rds(on))- Gate resistor (if applicable; no more than a couple ohms, unless you need it slower*)- Transistor lead inductance (~8nH)- GND return path- And of course any stray inductance in all these paths along the PCB.*Of course if you need it slower (say for EMI reasons), you can cheapen the driver a good bit.Likewise the drain circuit has a loop including:- Transistor D-S (~8nH, and ESR of Rds(on) when on, or C of ~nF when off)- Opposite side transistor D-S (if applicable; take half bridge for instance)- Supply bypass C (and ESR, ESL)- And PCB strays.For the gate circuit, you have a total of maybe 20nF + 3 ohms + 30nH. This RLC circuit has a resonant impedance of Zo = sqrt(30nH/20nF) = 1.5 ohms. ESR > Zo, so it is overdamped. There is no need to further minimize inductance, nor to increase RG.For the drain circuit, you have a total of maybe 24nH + 4nF, for an impedance of 2.4 ohms. But ESR is maybe 0.3 ohm! So, if this resonance is excited, it will exhibit considerable overshoot, leading to failure!The resonance has a quarter period of pi*sqrt(24nH*4nF) = 15ns, which is on the order of times we expect to see here (gate switching will occur in < 80ns, so the Miller plateau will easily be started, crossed or finished in this time period). So expect large overshoot (~60%?).What to do about it?Add inductance.If the load is 300V and 50A, then the load impedance is around (300/50) = 6 ohms. Adding ESL to bring the total to ~100nH will raise the switching impedance Zo to the same level. This only makes things worse at first (more reactance means more parasitic energy stored during a switching cycle), but the first step is to make the inductance manageable, and balanced. Now, when the inverter is lightly loaded (in hard switching), it dissipates maximum power in junction capacitance; when loaded with rated inductive load, it dissipates maximum power in snubber inductance.Now we add a clamp snubber. Since the supply inductance is modest (~80nH added), we have some opportunity to add an RCD clamp snubber circuit across it. The capacitor and diode may have ~20nH (a large part of which is equivalent from the diode's turn-on speed (forward recovery) -- you'd use a junction diode here for the lower cost and capacitance), which is 1/4th the supply loop inductance so we won't be doing too badly here (we can expect a similar reduction in overshoot).The C value needs to be some times the loop capacitance (>3x, otherwise it charges too much during the spike), and R needs to be small enough so the capacitor is discharged (> 2 RC time constants) before the next pulse. The diode handles very little average current, but cannot be too small (I think the failure mechanism is electromigration; follow the repetitive pulse rating if present).Now the resistor dissipates the majority of commutation losses. It doesn't need to be fancy; a tubular ceramic resistor is fine, or you can build a converter to recycle the clamp energy. (A quasi-resonant \"lossless\" snubber can be used to recycle its own energy as well, but this increases the turn-on peak current, and usually needs more voltage overshoot. In other words, solves the problem by making things worse again. They can be appropriate for some converters though.)Tim"
}
] |
2025-10-17T19:19:30.453661
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-big-and-old-c0g-10nf-leaded-capacitor/
|
[ASK] Big and old C0G 100nF leaded capacitor - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 10, 2016, 07:14:22 am",
"content": "Bought this on impulse recently at our local component store, its quite old and even the store keeper put on sale.Even though I do NOT need it, its the C0G dielectric type, also reputable name Kemet and also quite big 100nF (imo) tickled my hoarding nerve.Aware that C0G is stable and usually for timing application, even though can't beat silver mica (isn't it ?), just wondering what kind of application need this kinda of relatively big capacitance of C0G cap ?Any comments are also welcome.The only printed label at the cap :KEMETC512C0G -> Checked at Kemet, C512 is the case size , C0G = aka NPO104J -> 100 nF 5% tolerance100V9609 -> 1996, quite old isn't it ?Attached below photo of the caps compared to TO-220 ic size."
},
{
"post_id": "",
"author": "chris_leyson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 07:45:49 am",
"content": "Hi BravoB, if they are marked 104J then that is 10 followed by 4 zeros, 100,000n or 100n. Temp characteristic is +/- 30ppm per degree C."
},
{
"post_id": "",
"author": "MK14",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 07:47:01 am",
"content": "Beaten to it, above..What makes you think it is 10nF ?It appears to be a 100nF, 0.1uF cap ?104JIgnoring J,tolerance10, then 4 (zeros) = 10,000 = 10 x 10,000 = 100,000 pF = 100nF104J are used somewhat often (when making stuff) by me as decoupling capacitors, so it would be difficult to forget.But I looked it up anyway (to avoid embarrassingly being wrong....)http://www.csgnetwork.com/capcodeinfo.html"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 10, 2016, 07:48:23 am",
"content": "Thanks guys, silly me, 1st post & title corrected."
},
{
"post_id": "",
"author": "chris_leyson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 07:57:33 am",
"content": "Hi BravoV, at 30ppm/C tempco they would be OK for a timebase."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 02:35:11 pm",
"content": "Those Kemet molded-box capacitors are excellent units. Inside is probably a 1206 or similar size monolythic (chip) capacitor."
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 03:23:09 pm",
"content": "Like semi-accurate/stable RC analog filters.They are handy for protoyping and such. You can bend the pins and solder it directly to a SO8 package."
},
{
"post_id": "",
"author": "Audioguru",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 04:44:58 pm",
"content": "I think it is a ceramic capacitor, not silver mica."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 09:38:38 pm",
"content": "Low loss, good for RF and power switching. The lead inductance is kind of unfortunate (not as good as an SMT chip!) but it can still be useful for low voltage/low impedance resonant circuits, high stability and so on. Maybe a low voltage, LF to MF range, RFID transmitter?I forget what dielectric absorption is like on those, probably not as good as classic polystyrene, but it's the best ceramic you can get, in any case. I don't think it would be bad for S&H sorts of things.Tim"
},
{
"post_id": "",
"author": "Cerebus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 09:56:32 pm",
"content": "Quote from: T3sl4co1l on March 10, 2016, 09:38:38 pmDielectric absorbance is fair to very good on C0G/NP0 caps BUT it can vary by a factor of around 100 between different brands/ranges of nominally identical capacitors (i.e. same value and voltage rating). Some are slightly better than polystyrene, some are just worse then polyester, none are as good as PTFE. Annoyingly it rarely makes it into the datasheets so you either have to get some and test it yourself or find a knowledgable application engineer at your chosen capacitor vendor."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2016, 11:16:42 pm",
"content": "Also, NP0/C0G has a specified temperature co-efficient of 0 +/- 30 ppm/C, but silver mica has between +35 and +75 ppm/C."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 11, 2016, 01:20:17 am",
"content": "I'm aware of other dielectric type like PTFE or Silver mica, its just mostly they have quite small capacitance in pF range, while this one is at 100nF, and according to Kemet literature, it doesn't age, also has a linear tempco, cmiiw.Btw, this particular cap aint cheap either, like at Mouser cost about $23 a pop->Kemet C512C104J1G5CA.Actually what I have in mind with this huge cap is to turn it into sort of \"good enough\" enthusiast grade long term stable cap that once measured (& profiled with high end LCR meter), it will be a reference cap for years to come, is it suitable for this job ?"
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 11, 2016, 03:45:14 pm",
"content": "Quote from: BravoV on March 11, 2016, 01:20:17 amWhatta? Someone put the decimal point the wrong place."
},
{
"post_id": "",
"author": "quarks",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 11, 2016, 08:09:14 pm",
"content": "Quote from: BravoV on March 11, 2016, 01:20:17 amIf I had one of these, I would exactly do that and keep it for long time comparisons."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 11, 2016, 09:07:46 pm",
"content": "Note that traditional General Radio standard capacitors, either mica or polystyrene, were in hermetically-sealed packages to avoid problems with humidity affecting the capacitance. If you mount your NP0 device in a box, take measures to avoid humidity."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 12, 2016, 01:14:57 am",
"content": "Quote from: TimFox on March 11, 2016, 09:07:46 pmThanks, I guess I have to come out with a way to sort of seal it, maybe in a small glass jar filled with silica gel, and with only two leads out while the whole unit will be sealed maybe using hot glue gun or epoxy."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 13, 2016, 04:04:17 pm",
"content": "Do not use hot glue, it is not vapour resistant. Glass jar with a feedthrough ( probably a waterproof BNC connector per lead, fitted with some slow cure epoxy during installation) connection, filled with some very dry silica gel ( deepest blue you get after baking in an oven for 2 hours at 140C) and then seales with the same epoxy."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 14, 2016, 08:56:47 am",
"content": "Quote from: SeanB on March 13, 2016, 04:04:17 pmGood idea SeanB, especially on the feedthrough BNCs. thanks.Time to find a suitable jar, with metal lid that wont corrode."
}
] |
2025-10-17T19:22:29.567629
| 18
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-coaxial-rg-174-vs-rg-58-with-length-under-150-cm-or-5-feet/
|
[ASK] Coaxial RG-174 vs RG-58 under 150 cm or 5 feet - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 28, 2017, 02:21:33 am",
"content": "Does it matter much ?I'm about to make another batch of relatively short coax cables with BNC connectors for my electronic bench. And quite favor the RG-174 coax as its quite thin & flexible, and also its quite a space saver if you have a bunch of them rolled and stacked on the bench compared to RG-58.Scope of this discussion is for the T&M interconnects like from/to scope, FG, active probes and etc, that will be used at the bench only, with working signal is under 500 MHz."
},
{
"post_id": "",
"author": "helius",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 28, 2017, 04:51:52 am",
"content": "RG-174 is higher loss, but with short cables that isn't significant. I believe RG-58 has a higher dielectric withstanding voltage, but this will be practically limited by your connectors, so may not matter in actual use."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 28, 2017, 09:34:22 am",
"content": "I made myself a couple of RG-174 and RG-316 patch cables and while they are useful, their major disadvantage is that the thinner cable is fragile compared to a thicker cable. My favorite patch cables use RG-400 which is the diameter of RG-58 but double shielded."
},
{
"post_id": "",
"author": "CJay",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 28, 2017, 11:06:34 am",
"content": "I lucked into a couple of bags of brand new 1 Metre RG174 BNC-BNC cables in a bargain bin at a component supplier, they've been excellent for my needs (HF to UHF) and have proven to be reliable in the year or so I've been using them to hook up test gear (frequency counter, 'scope, spectrum analyser with relevant adapters, modulation meter etc...)"
},
{
"post_id": "",
"author": "SingedFingers",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 28, 2017, 12:38:54 pm",
"content": "Incidentally you can buy RG174 by the metre here:http://www.spectrumcomms.co.uk/Aerials.htm#FEEDER%20CABLE%20&%20PATCH%20LEADSGood company."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 29, 2017, 01:54:38 am",
"content": "Thanks for the feedbacks guys, RG-174 it is.Quote from: David Hess on March 28, 2017, 09:34:22 amAs patch cables only which are only like 4 or 5 feet ( 150 cm) length, is there any significant difference between RG-174 and RG-316 ? What max working frequency do you usually work on when using these ?RG-400, yeah, it would be an ideal like for fixed/permanent cable between T&M equipments, apart from double shielded, its also has stranded core that make the cable quite flexible compared to the stiff solid core coax, its only for patch cables. Its just really hard to find it locally here, and probably way too expensive for just few meters for my needs.Anyone want to sell me just \"few\" meters of RG-400 ?"
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2017, 12:07:28 pm",
"content": "Quote from: BravoV on March 29, 2017, 01:54:38 amLoss is mostly dependent on cable diameter so solid polyethylene RG-174 and Teflon RG-316 perform almost identically. RG-316 is a little easier to work with because the Teflon dielectric will not melt at soldering iron temperatures. Incidentally, both make great shielded audio and microphone cable.I can see the difference in edge and dribble-up response between RG-174/RG-316 and RG-58/RG-400 at 300 MHz but not at 100 MHz.QuoteI used to pick up RG-400 from the cable guy at the ham radio swap meets. It does not age like RG-8X so I never worried about old stock.There is a double shielded solid conductor version of RG-400 (RG-142?) which should be almost as good and is probably easier to work with. The Teflon dielectric and double shielding of RG-400 make it pretty stiff even with its stranded center conductor."
}
] |
2025-10-17T18:59:49.863463
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-converting-typical-buck-switcher-into-split-rail-power-supply/
|
[ASK] Converting typical Buck switcher into split rail power supply - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 13, 2016, 08:28:58 pm",
"content": "Just curious if is it that simple to make a typical Buck switcher to generate positive and negative rails using this method ? Any other considerations ?TIAEdit : Some corrections"
},
{
"post_id": "",
"author": "Paul Price",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2016, 02:51:41 pm",
"content": "No.If the circuit you show is very lightly loaded both the Virtual-Ground and V+ outputs would have about the same output voltage refereced to V-Negative."
},
{
"post_id": "",
"author": "chris_leyson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2016, 03:25:16 pm",
"content": "You could also us a single switch in a combined SEPIC and Cuk converter, see Analog Devices app note AN-1106.http://www.analog.com/media/en/technical-documentation/application-notes/AN-1106.pdfAnother option is a \"flybuck\" converter and wire up the coupled inductor to the negative rail, a word of warning though the rail generated by the coupled inductor has NO short circuit protection."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 14, 2016, 03:45:48 pm",
"content": "Quote from: Paul Price on November 14, 2016, 02:51:41 pmAre you saying the V-Ground and V+ must be loaded all the time, or both rails V+ \"and\" V- must be loaded at the same time and all the time ?I got the idea after reading TI's app note ->SLVA369A - Creating a Split-Rail Power Supply With a Wide Input Voltage Buck Regulator, and thinking if I can apply the example like this one below at \"other\" buck switcher ?"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 14, 2016, 03:47:06 pm",
"content": "Quote from: chris_leyson on November 14, 2016, 03:25:16 pmThanks Chris, never read that b4, noted on the short circuit weakness."
}
] |
2025-10-17T19:08:31.484635
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-incandescent-lamps-in-series-for-load-testing/
|
[ASK] Incandescent lamps in series for load testing. - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "August 01, 2017, 02:42:36 am",
"content": "Scored a really cheap, used AC/DC converter recently (photo attached), and I was only allowed to do on site test at the output voltage but unloaded with DMM, and it was spot on.As its output max out at 36 Volt at 46.5 Amp, I have problem finding the suitable load at 36 V in order to load test it, and I mean quick & cheap way at constant load only. I do have many of car's 12Volt incandescent lamps, just lets assume they're all same model and spec.The question is, can I use three of these lamps (12 V x 3 = 36 V) \"in series\" to load test this PSU ?All I need is to test whether its capable of running say at about 30 plus Amps for about 6 hours, and also planning to measure it's output quality with scope while on load, and do some simple temperature measurements.Also if there are any other tips for testing or verifying this particular PSU, I'm all ears.Thanks in advance."
},
{
"post_id": "",
"author": "alm",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2017, 03:07:31 am",
"content": "Since incandescent bulbs have a positive temperature coefficient, I would expect this to work fairly well as long as you use lamps with the same voltage and current ratings.An alternative might be this (although 6 hours might require a very large bucket or replacing the water multiple times):"
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2017, 10:38:13 am",
"content": "36V * 46.5A = 1674W = 1.674kJ/s which is coincidentally almost exactly 0.4 of the specific heat constant of water, 4.184kJ/kg/K. It'll raise the temperature of 1L of water 0.4 degrees per second, or 200 seconds for an 80 degree rise (assuming 20C to boiling). 10L will take 2000s, 100L will take 20000s (5:33:20). Alternatively, it will take 6h to boil 108L of water at that power."
},
{
"post_id": "",
"author": "oldway",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2017, 02:16:17 pm",
"content": "A very cheap solution is to use inox MIG welding wire to make power resistors.A 0.8mm diameter wire can take up to about 5A at free air....For 12V, I use about 1M of wire.In order to wind it, it is first necessary to anneal it by elevating his temperature up to red hot."
},
{
"post_id": "",
"author": "MrAl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2017, 06:38:36 pm",
"content": "Hello,I've used power resistors in distilled water, and it works pretty well at low voltages. Never tried it at high voltage like 120v.I've also used light bulbs and there is one caution.light bulbs have a very large dynamic resistance range. They can start out at around 1/10 the resistance of what they are when hot. So a 12v bulb that draws 1 amp when hot (12 watts) could draw 10 amps when first turned on, then quickly heat up. Trouble is inverters may trip on overcurrent before the bulbs heat up when you get nearer to full load. To get around this you might be able to switch them on in banks, one at a time. For example, of you wanted to test up to 360 watts and had 12v 1 amp bulbs, that would be 36 watts per string, so you'd need 10 strings of 3 bulbs each. Turning them on one at a time would probably prevent the inverter from going into over current limit, or at least maybe the last 5 strings should be turned on one at a time.They also sell load cones that have nichrome wire wound around a ceramic cone. They screw into a standard 120vac light bulb base. The wattage varies up to 1000 watts each, but that's at 120v volts, so each one may only be about 100 watts at 12v, maybe 300 watts or so at 36 volts. They are made to take the heat even when they get red hot, which is at 120vac, so they can run for hours but they will heat up the room fast because after all they will be putting out a lot of heat. A typical room electric space heater is 1000 watts or a little more, so go from there."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 02, 2017, 12:43:21 am",
"content": "Simple answer is Yes.If you want to test 36V @ 30A, then you are talking 1.08KW. That's a lot of light.If you want to use the classic 21W/5W automotive stop/tail light (using both filaments) - you will need42of them ... 14 parallel strings of 3 globes in series (with the filaments of each globe in parallel). The numbers put that at 1.092KW - but with a few losses thrown in, it should be pretty close to your target."
},
{
"post_id": "",
"author": "BrianHG",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 02, 2017, 12:59:20 am",
"content": "I would use 11 * (3 halogen spot light 12v 50 watt bulbs in serial). Dirt cheap, BUT, having 33 bulbs on all in 1 area will be like a space heater...The only annoying thing is wiring them without sockets is a pain because wire wont solder to the pins too well..."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 02, 2017, 02:10:30 am",
"content": "Quote from: BrianHG on August 02, 2017, 12:59:20 amYou could put them outside around the house..."
},
{
"post_id": "",
"author": "MrAl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 02, 2017, 02:23:26 pm",
"content": "Hi,That would be one heck of a night light :-)Biggest bulb i had in the past was a 300 watter. I used it mostly as a load for testing stuff."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "August 03, 2017, 03:46:52 am",
"content": "Thank you all for the replies !Also appreciation to @amyk for the heat calculation, now I have a picture how much water that I'm going to deal with, and also MrAl for the incand bulb cold resistance, must think of sequential turn on at the arrays of bulbs in parallel.As using cooled wire in water, this need to be fully attended even with plenty of water, and also I need to find a suitable place to test it, no way going to turn my little puny lab into steam bathroom.If I'm going to use water as Mike does, will copper wire from unwind from broken transformer is enough ?Have to find one that suitable for shorting it in 36 Volt @ +30 Amps ..."
},
{
"post_id": "",
"author": "MrAl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2017, 11:36:08 am",
"content": "Hi again,Watch out when you do the load immersion in water thing. If the surface area of the part being used for the load is too small it can cause local heating even in the water. This will cause the water to boil near the location of the wire even though the rest of the water is not boiling. Depends highly on how much power is present over the given surface area. Lowering the current will stop it.Power resistors work pretty well, but there could be problems if it is pushed too far because of internal hot spots. A check on the resistance would tell if the resistance is changing too much as it heats up. Keeping it within reason would be wise."
},
{
"post_id": "",
"author": "alm",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2017, 11:41:28 am",
"content": "Some stirring should help against local hotspots, though of course the thermal resistance from resistive element to water will ultimately limit the maximum power dissipated by the resistor."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 03, 2017, 11:41:55 am",
"content": "I have a 27R load resistor. Lots of power dissipation capacity, especially in water.Same model as this:"
},
{
"post_id": "",
"author": "Kjelt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2017, 11:56:20 am",
"content": "Quote from: BrianHG on August 02, 2017, 12:59:20 amAh but they are the exact fit for a what we in Holland call a kroonsteen (crownstone) and the Germans call Europaklemmen (european clamps) but I do not know or can find the english term.They are these rows of plastick 1:1 connectors for mains with a small screw inside and you break off the amount you need, they are in multiple sizes and distances, some do fit these bulbs quite nicely.Due to the heat you do need the porcelain version as in the second picture."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2017, 03:41:06 pm",
"content": "2x parallel 230V 18\" 1KW ceramic wirewound bar fire elements, with 6 equally spaced narrow stainless Jubilee clips on each wired alternately to either end of the element to convert each to 7 paralleled sections of approx 1/7 the resistance would also be in the ball-park for a 36V 46A load. Use heat resistant, or even bare wires, bolted to a hole drilled in the tail of each clip and alternate the tail directions so the paralleling wires can be on opposite sides of the element. The connections are chunkier and the elements less fragile so its probably easier than trying to hook up 33 50W halogens without the proper sockets. Build it on a shiny metal sheet and you only need high temperature insulation for the element support brackets - through bolt ordinary steel L brackets with over-size holes, on mica sheet with mica washers (+ a steel washer on top) under the bolt heads and pack between the bolt and the oversize hole with natural fiber string (which may carbonise) or glassfibre string to keep the bolt centered. You've still got that pesky 1.67KW of heat output, but at least its dry radiant heat, not steam so if you can point it out of an open window, you can run your load all day.Adjust one bar at a time with the other out of circuit so you are running somewhere near 50% load. If the load is too high, disconnect one end terminal and if still too high, move the last clip towards the disconnected end. If its too low close up the Jubilee clip spacing towards one end till the hot resistance is slightly too low (measure it by powering 4 sections and measure the current into the center pair), then move the last clip back towards the other end to fine trim it."
},
{
"post_id": "",
"author": "Delta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2017, 04:32:50 pm",
"content": "\"Ah but they are the exact fit for a what we in Holland call a kroonsteen (crownstone) and the Germans call Europaklemmen (european clamps) but I do not know or can find the english term.\"The British sparky slang terms for those is \"choccie blocks\", as they look like a chocolate bar."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2017, 05:04:16 pm",
"content": "Yes but tightening a porcelain screw terminal block on the pins of a glass pinch GU5.3 base risks cracking the bulb and with 33 to do the odds are against you.If one wanted to go down the bulb route, personally, I'd pick up a job lot of cheap pigtailed GU5.3 sockets off EBAY, mount them all on a 7.5 cm grid to a polished metal baseplate (must be polished because dichroic reflector bulbs put most of the heat out the back), and wire them all in series at the back with each node brought out to one way of a porcelain screw terminal block (or a regular one on a thermally insulating standoff). By daisy chain (up to the wire ampacity) jumpering 1 of N ways of the terminal block alternately to either supply terminal, you can reconfigure it as parallel strings of N bulbs to suit any voltage that's multiple of 12V, or leave part of the array only connected at one end to reduce the total load."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "August 04, 2017, 03:34:12 am",
"content": "Quote from: Ian.M on August 03, 2017, 03:41:06 pmThank you, you've made me think of heating element for iron.Here locally, the replacement part for iron are abundant and cheap, most are rated about 300 Watt at 220 Volt, and usually priced just about $ 0.5 per piece. Fyi, here mains is 220 Volt.They look very similar to this, and comes with different variety of connection terminals.(random photo taken from Google search)Of course they will be submerged into the water or flowing water, I've been thinking to use a big bucket and just put the water hose in it and let the water run during the test period.Now, more questions :1. Can I use these in 5 or maybe 6 of in parallel ?2. Safety concern, as I'm going to do this in a wet environment, lets say I've secured and isolated \"ALL\" mains 220 Volt wiring at this power brick, \"AND\" with earth connection at the brick is also properly done. Also the unit is relatively far from the water tank. Is it safe to expose the 36 Volt DC ? With the possibilities that my body may get connected accidentally with it, either directly or thru the water.3. Do these type of iron heater element has similarity to incandescent bulb at the cold and hot resistance as Mr.Al mentioned ?Also just fyi, this is the specification of the converter :"
},
{
"post_id": "",
"author": "Beamin",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 04, 2017, 03:42:28 am",
"content": "Quote from: alm on August 01, 2017, 03:07:31 amAS soon as I read the first post this was exactly what came to mind: An English voice saying \"Right...\" then a big bucket full of water and a jumble of wire. Stop reading my thoughts."
},
{
"post_id": "",
"author": "Beamin",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 04, 2017, 04:03:42 am",
"content": "Quote from: amyk on August 01, 2017, 10:38:13 amWon't the 200 second rise just bring the water to 100'C but to get to boiling you need to put in much more energy (8 or 10 times IIRC) as its a state change to go from 100'C water to 100'C steam? Would be a fun experiment to try."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 04, 2017, 04:18:26 am",
"content": "A1. The iron's hot element resistance is about 160R. The outer sheath surrounds the mineral powder insulation and is normally grounded, so no you cant tap the element part way to parallel section of it. You'd need about 200 elements paralleled for your load, so unless a pallet of them falls of the back of a lorry in front of you, they are no good to you. If you do have a pallet-full they'd dissipate about 8W each @36V, probably low enough for fan assisted air cooling.A2. Its under 50V, with a floating output and 3KV RMS isolation between its primary secondary and secondary sides, so it *probably* can be categorised as SELV, and is fairly safe. However if you ground either side of the output it becomes far more dangerous - consider the scenario of you tripping and ending up on your knees in a puddle with your arm in the tank. 36V DC diagonally across you body with large area abrasions in contact with wet conductive surfaces. As little as 42V DC can be lethal with enough low resistance contact area so I'd treat a wet area 36V system with *EXTREME* respect.A3. Got an iron in the house? Measure its cold element resistance (pin to pin on the mains plug) then calculate its nominal hot resistance from its rated wattage and supply voltage.I would expect some change but far less than the 10:1 ratio typical of incandescent bulbs."
}
] |
2025-10-17T18:51:18.217655
| 21
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-precautions-needed-for-a-noob-with-a-spectrum-analyzer/
|
[ASK] Precautions needed for a noob with a spectrum analyzer - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 14, 2018, 10:15:03 am",
"content": "Recently by luck, scored an used bench type 9KHz - 3GHz spectrum analyzer, and as noob regarding this fine piece of T&M equipment, I have read few precautions needed (more to read), and think I need to hear experienced members here regarding your wise advice.This is my SA's input :Click to enlarge.So please excuse few 1st noob questions :- Is it important to always use the so called \"DC Block\" adapter on the input to reduce the risk oftypical noob's mistake? Or any other comments on this.- Aware there are so many \"cheap Aliexpress\" type sales on this DC block, are they \"decent\" for this SA ? Yes, I'm currently lurking & stalking a 1st tier branded used DC Block online. Or any other suggestion ?- What is the RF Surge Protection ? As locally I got an offer of one of this, can I use this \"temporarily\" to secure the SA instead of a real DC Block adapter as this needs time to score a good one yet relatively cheap, and no, I can't afford a new one.- Or any other suggestions or advice for a noob, please.Thanks in advance for your help."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2018, 10:30:57 am",
"content": "You'll need the official datasheet to be sure how much the input can handle.The SSA3000X models are rated similarly:Maximum input DC voltage +/- 50 VDCVDC isn't all you need be concerned about, more so max dB and that can be managed with internal attenuation (again check datasheet for how much is available) or external attenuation. 20dB is a pretty normal value to have on hand and it's the default (not max) internal attenuation for SSA3000X models."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 14, 2018, 10:35:37 am",
"content": "Quote from: tautech on March 14, 2018, 10:30:57 amMy SA official datasheet ->NS-30 Spec (PDF)"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2018, 10:47:50 am",
"content": "Quote from: BravoV on March 14, 2018, 10:35:37 amThe important stuff is there:QuoteQuoteNow you just need to learn how to drive it !Dive over to the SSA3000X thread and look at the excellent usage examples by rf-loop.https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2018, 11:22:13 am",
"content": "BravoVFurther to just point out the modern approach is have an integral DC block which your unit by virtue of a 50V input rating will have.When I got my SA I had similar fears to you of damaging the input but with some little knowledge gained from members here and very careful initial small steps you will gain confidence as to what you can do with it.Achieving useful results on the display with just a near field loop is a safe way to make progress and become familiar with the UI before advancing to actual connection to a DUT.Play it super safe and conservative to start with and you'll be fine."
},
{
"post_id": "",
"author": "PA0PBZ",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2018, 11:53:13 am",
"content": "That arrestor isNOTa DC block, it is a lightning arrestor and will happily conduct DC because most GPS antennas do have a preamp built in.What you need is a DC block which is simply said a capacitor, the trick is to get a capacitor that is big enough to not attenuate the lower range of the SA (9 KHz).So check the specs of any DC block you are going to get and see if the lower range is acceptable for what you are going to feed the SA with."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2018, 01:12:27 pm",
"content": "Quote from: PA0PBZ on March 14, 2018, 11:53:13 amAnd linear enough that high voltages don't change its capacitance, thus changing the low frequency cutoff and/or creating harmonics.QuoteYes.Don't try to make your own. For RF (as opposed to audio) look at Minicircuits."
},
{
"post_id": "",
"author": "Shock",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2018, 02:36:20 pm",
"content": "Gotta measure em all! Went through a similar process when I got mine though I'm mainly interested in ULF to LF. I think it is common sense, similar to a scope you need to have an idea up front of the characteristics offset/amplitude of the signal you are measuring before connecting the front end, try not to use the instrument as an exploratory tool and use attenuation if necessary. You also have ratings on adapters and termination and need to be mindful to \"err on the side of caution\".These links have some tidbits, but it would be nice to see some deep dives on the subject. I'm always interested in how not to destroy gear. A nice project would be to make a few RF pads and a diode detector circuit.http://literature.cdn.keysight.com/litweb/pdf/5989-8791EN.pdfhttps://www.criticalcomms.com.au/content/test-measure/article/protecting-test-equipment-from-rf-damage-1405796639#axzz59jBWCOaYhttps://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/application_notes/1ma201_1/1MA201_9e_spectrum_analyzers_meas.pdf"
},
{
"post_id": "",
"author": "mnementh",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2018, 04:03:41 pm",
"content": "So what is the \"probe power\" for? A FET high-impedance probe, or an active attenuator probe of some sort?mnemEvery day you learn something is not a wasted day."
},
{
"post_id": "",
"author": "Shock",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 01:06:12 am",
"content": "Quote from: mnementh on March 14, 2018, 04:03:41 pmIt's a power source for compatible high impedance probes."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 03:17:51 am",
"content": "Quote from: tautech on March 14, 2018, 11:22:13 amThank you, I thought I was too paranoid, as current the SA input N connector is the 1st and the only one in the house, and currently I just powered it on as don't have anything and the ball to connect anything into it yet.What is \"near field loop\" are you talking about ? Mind elaborate further ?"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 03:19:40 am",
"content": "Quote from: PA0PBZ on March 14, 2018, 11:53:13 amThanks, noted. As I suspected.Quote from: PA0PBZ on March 14, 2018, 11:53:13 amNow, finding the \"right\" DC block that is good enough for my SA input range and also cheap, that is the hard part."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 04:19:35 am",
"content": "Quote from: tggzzz on March 14, 2018, 01:12:27 pmNoted, especially the DIY one, definitely its not in my plan."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 04:22:51 am",
"content": "Quote from: Shock on March 14, 2018, 02:36:20 pmShock, thank for the links and docs. Yes, I've watched the Alan's one hence the DC Block hunt.Curious, what kind of SA you have that does ULF to LF ?"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 04:24:57 am",
"content": "Quote from: Shock on March 15, 2018, 01:06:12 amYep, and still don't have any idea what kind of connector is that ?Attached below the close up shot and it's outputs rating."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 04:33:03 am",
"content": "Reading one of the Keysight document above, on the highlighted text, what is that ?Sort of a shorting cap for the N connector ?"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 04:47:32 am",
"content": "Quote from: BravoV on March 15, 2018, 03:17:51 amYou've a few options so I'll just give you some links in which to get a handle on them and then decide whether to buy something or DIY.https://www.eevblog.com/forum/projects/diy-magentic-field-probes/https://www.eevblog.com/forum/testgear/new-affordable-emc-probe-set-at-a-bargain-price-from-ariel-rocholl's-lab/https://www.edn.com/design/test-and-measurement/4380475/Near-field-probes-sniff-circuitsObviously if you need accuracy characterized probes are the way to go but I'd suggest you DIY from a loop of coax.That will at least get you started and give you a 'feel' for how to use a SA.You can use these on scopes too but you don't have the BW like a SA has."
},
{
"post_id": "",
"author": "Shock",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 04:47:48 am",
"content": "Quote from: BravoV on March 15, 2018, 04:22:51 amHP 3580a 5Hz-50kHz and I also have a HP 3581c selective voltmeter.Shown here but my HP 3580a has the balanced input (takes both balanced and non balanced sources) and battery option."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 05:02:54 am",
"content": "Let me just say I'm no wiz with a SA, just that I've had to come up to speed some due to wanting/needing to sell them.Read as much as you can, not just the links I've added and try to get a handle on those here that 'know their stuff'.I've mentioned one already and there's several more following whose opinions I deeply respect.Look here:https://www.eevblog.com/forum/testgear/kirkby-calibration-kit-alternatives/It can be a deep rabbit hole but it is fun."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 05:07:21 am",
"content": "Quote from: BravoV on March 15, 2018, 04:33:03 amNot all SA's are created equal....sensitivity, input robustness etc.Check if the KS has:Quote"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 05:08:44 am",
"content": "Quote from: tautech on March 15, 2018, 04:47:32 amGreat links, thanks again Rob.I guess I will be busy reading and gathering more infos especially on the DIY field probe 1st.Quote from: tautech on March 15, 2018, 04:47:32 amAccuracy on RF part is not my priority now, as this purchase is never planned, I didn't even expect to own a SA.It really changed a lot in my learning direction.My highest scope bandwidth is only at 400 MHz analog, this 3 GHz thingy is really quite a big jump in my T&M inventory."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 06:00:18 am",
"content": "Quote from: Shock on March 15, 2018, 04:47:48 amCool piece of equipment, ULF & LF .. no wonder with battery option for low noise stuff."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 06:06:05 am",
"content": "Quote from: tautech on March 15, 2018, 05:02:54 amYes, I'm aware of few fellas here looking the way they share/post their knowledge, that I believe are RF kung-fu masters.Quote from: tautech on March 15, 2018, 05:02:54 amDamn, I'm now just walking thru the hole's gate ..."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 06:22:29 am",
"content": "Quote from: BravoV on March 15, 2018, 04:33:03 amBasically a load of bollocks ! ( as far as ESD is concerned)We used to carry spectrum analysers all over the state without caps on the connectors.If you havep them, though, by all means use them, as they protect the thread on the outside of the \"N\" connector.( BNCs are worse, even though they don't have threads, they are much more prone to daThe problem is that, unless they are captive to the instruments"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 06:32:42 am",
"content": "Related to BNCs , other question, attached below the rear ports, I do know common types like serial, VGA, printer port, GPIB too, and the 10 Mhz reference clock BNC, its capable of as input or output.How about these BNCs ? Do I need a special extra precautions on these ? I am not saying like hooking up to mains voltage, but are they also ultra sensitive sort of like the main input ?Mechanically wise, I know how to protect BNC as I have lots of those silicone caps for BNC."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 06:38:44 am",
"content": "Quote from: BravoV on March 15, 2018, 06:06:05 amYou'll be captivated by it in no time.This is where I started and following posts show my SA newbie ramblings and growing confidence.https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/msg984038/#msg984038Study the GUI's shown for the many little visible clues on usage.Sure yours won't be the same however the same usage principles apply.One thing, check your documentation for the existence of an 'excessive input signal' warning alarm.....it's a bit like the confidence added when wearing a safety belt.....it won't save the SA if you do something stupid but it will warn you if you're pushing the input. Only had mine go off once when using a near field probe and the cellphone in my shirt pocket decided it should handshake with a cell tower some 5km away.Yes, they arethatsensitive !Quote from: BravoV on March 15, 2018, 06:32:42 amNo, just treat them the same as they were on a scope."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 06:40:09 am",
"content": "Quote from: BravoV on March 15, 2018, 04:33:03 amNo, the caps you will usually see used don't short the connector, they just cover the whole thing so the centre pin can't touch anything.In my opinion, the ESD reason for their use is all bollocks!We carried Spectrum Analysers all across the State without covers with no adverse effects.If you have them, use them as they protect the connector against physical damage.I have seen caps used on BNCs much more often than on\"N \" connectors, as the former are more prone to damage.Their biggest problem is that, unless captive to an instrument, they will easily be lost."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 06:53:56 am",
"content": "Quote from: vk6zgo on March 15, 2018, 06:40:09 amOk, noted, especially on NOT TOUCHING the central pin, thanks.Quote from: vk6zgo on March 15, 2018, 06:40:09 amIf its just for mechanical and dust protection, you mean sort of this cap right ? Example from Aliexpress ->N Dust Cap, its cheap too."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 06:58:54 am",
"content": "Quote from: tautech on March 15, 2018, 06:38:44 amWow !I'm not talking working at high power RF transmitter, or even a walky talky, but are you saying even using the near field probe and probing near a silly cell phone can toast the SA input ?Btw, looking at the spec of my SA, is the sensitivity level common ?Again, as a noob, I basically have no idea or fully understand yet, reading the majority part of the specification sheet."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 07:06:35 am",
"content": "But wait! ---- There's more!!!Re DC Block:-Nice to have, but you probably won't use it a lot.Over the years, I've noticed that such devices are the most \"new looking\" in the SA accessories kitAn external attenuators is probably a more useful device, as I've seen SAs where the front end has been \"cooked\" from excessive input signal level, but not from the application of DC.A 20 dB attentuator is very effective for input protection.In fact, as a resistive device, it will also reduce the level of any applied DC, whether by enough to protect the SA is in the lap of the gods!"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2018, 07:18:00 am",
"content": "Quote from: BravoV on March 15, 2018, 06:58:54 amPossibly, but it depends on the sensitivity of the probe, proximity andinput attenuation settings....they are your biggest friend when gaining experience. Always use some when initially investigating a DUT !So what happened that day, homing in on DUT signals just fine and reducing input attenuation for a lower floor and greater displayed signal amplitude when it did the handshake. Lesson learnt leave phone somewhere else when using a SA !Input attenuation is just one of the things to get your head around but the most important. Be it external or internal you must keep in your mind where you're at. SA's are so sensitive you must manage the input signal to within safe limits that are BTW far less that anything your'll encounter on 1M scope inputs.Start chucking some #'s into this and you'll see what I'm on about:https://www.rapidtables.com/convert/power/dBm_to_mW.html"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 07:53:09 am",
"content": "Quote from: vk6zgo on March 15, 2018, 07:06:35 amOk, say a decent DC Block that has a flat response on my SA frequency range is hard to find, or still very expensive. Still going to find one though, as I'm a complete noob, just so worry I accidentally toast the input.Now, we're talking bout attenuator, since my SA range is 9 KHz- 3 GHz, as they're so many choices, which one is the most suitable ?I mean say like examples between two that have spec of DC-3Ghz vs DC-10GHz, is higher one is better ? Or just a bit higher say DC-4GHz one, so the performance at 3GHz is still good enough ? Worry I may fall into trap for young player.Also correct me if I'm wrong if I've asked the wrong question, as I'm just starting to grip on these."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 15, 2018, 03:14:34 pm",
"content": "Quote from: tautech on March 15, 2018, 07:18:00 amThanks again, simple yet really important lesson for SA noob.Quote from: tautech on March 15, 2018, 07:18:00 amAgree, its just few days ago I just realized and understood clearly the \"power\" vs \"voltage\" as in SA vs scope, cmiiw.Scope measures voltage while SA measures power, that is one of the fundamental different, again, cmiiw.Of course on time vs frequency as well.Thanks again."
}
] |
2025-10-17T18:36:12.245942
| 33
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-pro-con-of-rectangular-shaped-enameled-copper-wire/
|
[ASK] Pro & Con of rectangular shaped enameled copper wire ? - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "January 24, 2017, 01:05:24 am",
"content": "Inductors using a rectangular shaped enameled copper wire, what are the pros & cons ?Example, random image from google."
},
{
"post_id": "",
"author": "KMoffett",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 24, 2017, 01:26:25 am",
"content": "I'm thinking these were for induction furnaces for melting metal. The rectangular cross section allows a very low resistance in a a very small space for passing a very high current.Ken"
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 24, 2017, 02:15:50 am",
"content": "Moffett is right about that application.Pros: Lower resistive loss within a given coil volume allowance if wrapped properly. Cheaper than silver as solution to resistive loss problems.Cons: More expensive conductor, more difficult to wind. Can have \"interesting\" skin currents/arcing potential, particularly at high frequency. With the exception of the inductive heating application, most uses I have seen are low frequency. Under 100 kHz."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 24, 2017, 10:15:35 pm",
"content": "I used rectangular wire in a DC electromagnet to improve the fraction of the \"coil\" volume that was taken up with copper, and to improve the heat conduction out of the coil. This was grad school, and I was lucky to find a surplus roll of insulated rectangular wire that was originally intended for a transformer."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 24, 2017, 11:42:52 pm",
"content": "Not so much -- I never seen 'em used for induction heating.Why? No cooling! The poor thing will melt, from the inside out, in under a minute (and that's at low power levels of several kW).Square and rectangulartubingis used a lot, though: but not because of losses. It's easier to fabricate. You can chop a piece into segments by making miter cuts (sealed with silver solder). It bends easily without kinking, even for fairly tight inside corners.Indeed, the losses are higher. Much higher! For a coil with dimensions as pictured above, there would be extremely high eddy currents induced in the coil itself (the eddy currents flow across and around the conductor, while the load current flows lengthwise). This forces the load current towards the inside corners (path of least impedance). Indeed, the effect is so strong that the outside corners will carry opposing currents (going backwards!), if not as intense as the inside corners' current.For any application where low losses are required (RF tank coils, most induction heating apps), round tubing is best, spaced with a pitch twice the tubing OD. This reduces the eddy currents, caused by the turns being so close together, without reducing the overall inductance too much (because it is stretched, relative to having pitch as close to diameter as possible).To put concrete numbers on it: the pictured coils might have a Q in the 20-50 range, depending on shape and frequency. A loosely spaced coil of round wire/tubing will have Q ~ 100-200, all else being equal. That's a big deal when you're resonating over 100kVAR!They do work nicely for cored inductors, and lower power levels. All the big name manufacturers have lines of inductors made this way: for example, Vishay IHLP series, lots of Bourns and Cooper (now Eaton) high current parts, Coilcraft high-current parts, etc.And of them, the powdered iron types are actually molded around the winding, so the core material completely fills the gaps and crevices between turns. You can't beat the amount of inductance available this way -- these things have dense ratings -- lots of inductance and amps in a small package.The Q factor improves about proportional to permeability, so they don't get terribly hot in the process, either. Add a permeability of 10, and Q shoots up from 20 to 200. In practice, it's worse than that, because of geometry factors and core losses. Typical Q for this type is 50-200: quite reasonable for a power conversion application that only needs to circulate 100s of VARs.And what is square/rectangular wire most ideal for? The applications that don't need to worry about skin and proximity effect: mains frequency transformers! The high winding factor (most copper area in the winding space; packing factor) allows a good ~20% improvement in current capacity, over round wire, for a transformer of identical construction (same wire width, same number of turns).Tim"
},
{
"post_id": "",
"author": "Richard Crowley",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 25, 2017, 01:19:41 am",
"content": "JBL (and perhaps others?) used to boast about their edge-wound voice coils.Quote"
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 25, 2017, 05:46:18 pm",
"content": "Quote from: Richard Crowley on January 25, 2017, 01:19:41 amExcellent reminder that there are always a lot of factors that go into the \"best\" solution for any problem."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 25, 2017, 05:49:24 pm",
"content": "Quote from: CatalinaWOW on January 25, 2017, 05:46:18 pmIndeed -- note that my complaints of poor electrical performance, are easily overruled by the other requirements of a voice coil: light weight for one, and for that matter, poor efficiency is actually a desirable trait (since coil resistance leads to acoustic dampening).Voice coils are also a low frequency application (as the wire is concerned), which puts them in the same regime as power transformers: better fill factor means more power in the same space!Tim"
}
] |
2025-10-17T19:04:32.100008
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-scope_s-50-ohm-input-mode-why-crap-scope-don_t-have-it/
|
[ASK] Scope's 50 Ohm input mode, why cheap scopes don't have it ? - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 21, 2012, 08:25:59 am",
"content": "Just a noob question, understand the objective to reduce the cost, but from technical point of view, does it really need expensive front end components and / or advance electronic design/build that can make huge or significant difference in the cost of making it ?Appreciate any comments or technical insight why they don't provide it at low end models."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2012, 09:24:04 am",
"content": "A switchable 50 Ohm termination,is in my opinion,a bit of a gimmick,although some people are very taken with them.Most older Oscilloscopes don't have them.Unfortunately you can't just stick a toggle switch & a resistor across the input,as a switched termination needs a bit of finesse in design at high frequencies.Special switches must be designed,or relays used,all of which adds mechanical complexity & creates possible reliability issues.Afixed50 Ohm termination would severely limit the versatility of your 'scope.Through terminators are available for both 50 & 75 Ohms,which are,again in my opinion,a more versatile way of using a terminated input.The external terminations usually have a higher power rating,but if you do cook one,you don't have to replace any bits in your 'scope."
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2012, 09:39:35 am",
"content": "The normal reason for 50R inputs are for use with active probes, which are expensive, and for high frequencies, so users of cheap scopes don't have any need for it, and the additional cost is not justified."
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 21, 2012, 09:51:15 am",
"content": "The reactance of the 1 Mohm inputs becomes a problem at high frequencies, so an external terminator works just fine at 50 MHz. I don't agree that it's a gimmick. With an external terminator, there's still the input capacitance of the scope in parallel, which screws up your VSWR. Most fast scopes might have 1+ GHz BW at 50 ohms, but only 500 MHz at 1 Mohm."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2012, 01:12:33 pm",
"content": "The value of Xc for a 1 Mohm input is going to have a lot less effect when the 1Mohm is shunted by 50 Ohms.That said,yes,an input stage designed from the outset for 50 ohm impedance should be capable of better frequency response.----conceded!From what I have seen,some of the \"50 ohm\" inputs are,as I suggested above,just switched terminations,still using the 1Mohm input.I still regard these as \"gimmicks\".As I said earlier,fixed50ohm inputs reduce the versatility of the instrument,& for normal use ,especially by a beginner,are unnecessary."
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2012, 01:25:21 pm",
"content": "You want to keep the impedance constant to the real input ( the first amplifier )So this means from your pickup point , through the coax, through the bnc or mxc ( hf scopes do not use bnc's , or specially modified bncs with less dielectric / not stupid plastic but torlon or even kapton as isolator . Look at the bnc of a 1 ghz scope.. It does not look like the bnc of a 10MHz scope ... Ill take a picture of mine and post it. Notably different.... ) all the way on the pcb in the scope to the first active element.So ,adding the terminator outside fools you , because the last stretch , in the connector , on the board is not covered.Simply adding a switch is no solution either. It has to be done at the right place and in the right way. In 'real' scopes this is done in the front end hybrid or chip. Wing wang pong scopes... May be a simple through hole relay... Good up to a few 100MHz.. Above that ... Needs self wiping contacts and shielded switches.As for scopes with a fixed 50 ohm input. The machines i have at work are in that category. Once you hit the 2GHz and above machines it is fixed 50 ohm... No high impedance option, not even switchable.... Only to be used with active probes. Amplifier in the tip , 50 ohm all the way in to the digitizer."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2012, 02:12:14 pm",
"content": "The OP,as far as I know,just wants to know why some (most) Oscilloscopes do not have 50 ohm terminations.In my reply,I pointed out the main reasons why.I also conceded your point on continuity of impedance.I still maintain that for most normal work,an ordinary 'scope with an external termination is adequate.The OP is unlikely to require specialist 'scopes like you use at work.Most UHF work outside your special area is done using Spectrum Analysers in the frequency domain.These devices commonly operate up to & beyond 2GHz,they use \"N\" connectors with plain old PTFE insulation(not \"stupid plastic\"orkapton) and they are made by HP/Agilent,Tektronix,Anritsu,Rohde & Schwarz,etc,NOT \"Wing wang pong\"!"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2012, 02:51:09 pm",
"content": "even with my wing wang pong scope, long 50ohm coax cable need to be terminated with 50ohm externally (at the scope's bnc input). otherwise the signal will wing ping pong in the coax back to the source. just an ack."
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2012, 03:00:07 pm",
"content": "Quote from: vk6zgo on April 21, 2012, 02:12:14 pmPsst... Your age is showing. 2 GHz is no longer the exclusive domain of RF signal junkies. Most manufactures entry level 'pro' scopes go up to at least 1 GHz, and there are lots of general purpose scopes in the ~ GHz range.But yes, a cheap low performance low bandwidth scope doesn't benefit much from a integrated terminator compared to an external 'tee' with a 50 ohm terminator. Up around 500 MHz, you want integrated terminator. A good switchable termination should remove the 1 MOhm resistor and its compensation cap from the signal path, although I confess I don't know how many scopes meet my definition of 'good' here"
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 21, 2012, 03:50:51 pm",
"content": "I work in the harddisk industry. all digital stuff. Take the transceiver eye diagram of a usb3 or sata cell ? get the 20Ghz scope out .... it's all controlled impedance , matched line length stuff.Wanna look at the write signal going to the head of a harddisk ? that a 4 Ghz analog signal.. better have a real scope.and mechatrommer also has a valid point.Same goes for people using any kind of active probe ( detector probes, differential probes etc, current probes ) . these things all have built in amplifiers in the head and do need the 50 ohm termination on the back end.So , why fidget with external 50 ohm feed throughs . You are injecting 2 connectors. cable - bnc - feed through - bnc - scope. all the more risk of trouble."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 22, 2012, 01:14:57 am",
"content": "Quote from: free_electron on April 21, 2012, 03:50:51 pmBecause they are commonly used by thousands of people doing general Electronic work without any problemsIn Spectrum Analyser use ,external attenuators are commonly used without these problems you are worrying about.I never disputed that Oscilloscopes with responses of the kind you are referring to do need 50 Ohm inputs.Many perfectly adequate 'scopes do not have 50 Ohm inputs,& some lousy 'scopes do,so for general use I stand by my comment that they are \"a bit of a gimmick\"."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 22, 2012, 01:27:48 am",
"content": "Quote from: ejeffrey on April 21, 2012, 03:00:07 pm"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 24, 2012, 04:33:03 am",
"content": "Thanks for the responses, I think I got it now, if the context is for \"casual\" measurements , basically even the cost or design complexity difference is trivial, its very unlikely the cheap scope owners buying an active probe is almost none as Mike said."
}
] |
2025-10-17T20:34:28.197126
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(ask)-stacking-up-multiple-tvs-in-series/
|
[ASK] Stacking up multiple TVS in series - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 03, 2015, 09:20:46 am",
"content": "Currently I have only 5 Volt rated TVS in stock, plan is to protect power mosfet's Vgs (non logic level Vgs@20V max) by using 3 of these 5 volt TVSes connected in series to get up to 15 volt, also its only one off ad hoc project.Will these work ?"
},
{
"post_id": "",
"author": "rs20",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 03, 2015, 09:31:17 am",
"content": "Yeah, more or less. Your inaccuracies will be tripled, maybe check that it actually does shunt at the absolute max Vgs. Otherwise a nominal 5V TVS which actually trips at 8V * 3V = 24V Vgs and a dead mosfet. But the reason thatBy contrast, things like gas discharge tubes and trisils cannot be used in series, because the V/I curve is discontinuous so you might end up with weird halfway states. But TVSs just have a nice monotonic VI curve; and putting them in series just triples the voltages."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 04, 2015, 07:48:26 am",
"content": "rs20, thank you !"
},
{
"post_id": "",
"author": "Kjelt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 04, 2015, 12:44:56 pm",
"content": "Interesting, going to test this soon, saves me also an extra component to order"
}
] |
2025-10-17T19:30:58.150165
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(assignment)-need-to-make-the-most-simple-circuit-possible/
|
[Assignment] Need to make the most simple circuit possible - Page 1
|
[
{
"post_id": "",
"author": "UberStrike88",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 09, 2015, 05:33:50 pm",
"content": "Hi,Well I got a assignment today from school and the most simple circuit possible and it should be useful with the part you get.Some got a easy chip like the 7805 and some got something harder. Anyway I got this chip:AZ431-Ahttp://www.diodes.com/datasheets/AZ431A.pdfSo yeah it's a three-terminal adjustable shunt regulatorWell I have no idea it should be easy useful and it needs to be with the least parts you can use.Anyone got any idea?(yes we may ask around on forums)Regards,"
},
{
"post_id": "",
"author": "AndyC_772",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2015, 05:37:43 pm",
"content": "What's wrong with the application circuits in the data sheet?"
},
{
"post_id": "",
"author": "JacquesBBB",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 09, 2015, 05:38:44 pm",
"content": "Just look to the datasheet and make the first example. It looks perfect to me. To understand it, as well as thefunctional diagram schematic on page 4 is a perfect training for you."
},
{
"post_id": "",
"author": "UberStrike88",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 09, 2015, 05:42:18 pm",
"content": "Quote from: JacquesBBB on March 09, 2015, 05:38:44 pmOkay will try to make it although they don't specify what rating the resistors need to be"
},
{
"post_id": "",
"author": "AndyC_772",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2015, 06:08:12 pm",
"content": "No, but you can work that out for yourself. You know what the input voltage, output voltage and reference voltage are. Pick sensible currents, and then you can work out the power dissipation in each component from Ohm's law."
},
{
"post_id": "",
"author": "JacquesBBB",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 09, 2015, 06:13:55 pm",
"content": "As an exercise, you can demonstrate the formula of the first example : Vout = (1+ R1/R2) Vref. You will see that it does not dependson R3 nor on Vin.If you want to get benefit from this simple example, you will have to determine also the minimum and max values for Vin, and as said by Andy, the required specifications of the resistors."
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2015, 06:43:24 pm",
"content": "Love the 431, an op amp and a voltage reference. Voltage detectors,relay driver, time delay, even turn it into an audio amplifier."
},
{
"post_id": "",
"author": "Refrigerator",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2015, 08:14:19 pm",
"content": "Make the first example circuit and add a darlington transistor and you got yourself a little voltage regulator. Simple as that."
},
{
"post_id": "",
"author": "AG6QR",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 09, 2015, 11:51:03 pm",
"content": "Another idea: Add a single transistor, use the current source example from the data sheet, and you've got a constant current LED driver. It can drive an LED with 20mA (or whatever you design it for) over a wide range of input voltages."
}
] |
2025-10-17T19:45:42.013186
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(au)-inexpensive-kit-to-start-soldering-with-paste/
|
[AU] Inexpensive kit to start soldering with paste - Page 1
|
[
{
"post_id": "",
"author": "rthorntn",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "November 12, 2024, 05:03:03 am",
"content": "Hi,What to buy in Australia to get started, namely the heat source?Beginner stuff thats a bit small to hand solder (0402, SOIC & SOT).The paste seems like a right PITA for the occasional job, if I remember rightly it wants to be refrigerated and only lasts 6 months, so a lot of waste then, I guess there is no such thing as a long-life solder paste in 2024?Thanks!"
},
{
"post_id": "",
"author": "Hectorx1999",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "November 12, 2024, 06:24:37 am",
"content": "To start soldering small components like 0402, SOIC, and SOT, consider a hot air rework station for controlled heat and a fine-tip, temperature-controlled soldering iron. For occasional use, buy small quantities of solder paste to reduce waste or use fine-gauge solder wire instead. A flux pen and magnification tools will also help with precision. Unfortunately, long-life solder paste doesn’t exist yet, but proper refrigeration extends its shelf life."
},
{
"post_id": "",
"author": "rthorntn",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "November 12, 2024, 06:27:59 am",
"content": "Thanks, what do you mean by a \"hot air rework station for controlled heat\" when you're hand soldering with an iron?"
},
{
"post_id": "",
"author": "Anthocyanina",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 12, 2024, 07:03:44 am",
"content": "you will probably need both a hot air station and a soldering iron to get solder joints cleaned up on the smallest components. at least while you figure out the right amount of paste to use, the right airflow speed and temperature of the hot air.I have experience with a multicomp branded atten 862d and i'm happy with it, so i would recommend it. it comes with 4 tips, and you can get angled tips as well, which while i don't have them, i would recommend the angled tips if you do get it"
},
{
"post_id": "",
"author": "rthorntn",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "November 12, 2024, 07:24:36 am",
"content": "Thanks, so do you only do one component at a time, you apply paste (only with a stencil?), place the part and put low velocity hot air on it, and the iron is to fix any stubborn bits?"
},
{
"post_id": "",
"author": "BennoG",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 12, 2024, 07:36:39 am",
"content": "What I usually do is mix the paste with flux (50 / 50) about and use a thin wire to apply the paste to the right places.Even they I sometimes apply too much paste. By mixing it with flux you can extend the life to 2+ years.That is only for the small experiment jobs. I usually order pcb's with the small 0402 components placed on it and the \"special\" components I hand solder.Benno"
},
{
"post_id": "",
"author": "Anthocyanina",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 12, 2024, 07:40:26 am",
"content": "Quote from: rthorntn on November 12, 2024, 07:24:36 ammost of what i use it for is for repair, so i'm replacing one or a few components in an area at the same time. I'll remove the components that need to be replaced, clean the pads, put paste on them, place the new components, and run hot air over them. slow air speed has worked for me and it seems to be the common setting other people use as well. when using it for personal projects, if the board is small enough, i'll use hot air for all the smd components at the same time with a wide nozzle, or with the tips removed, and it's worked well for that. the iron i use for through hole components, and to fix solder blobs or the odd tombstoned resistor or cap. i have a very crappy soldering iron, so there's no recommendation on that side, but i'd like to get a pinecil or one of the basic hakko stations since either of those would be a big improvement over what i have right now"
},
{
"post_id": "",
"author": "rthorntn",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "November 12, 2024, 07:44:28 am",
"content": "Thanks, is that feasible, to have the fab just place the tiny stuff, on a board I'm looking at now that would be four SOT and twelve 0402 (out of a hundred SMT parts)?What do you mean by the \"special\" components, expensive stuff?"
},
{
"post_id": "",
"author": "BennoG",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 12, 2024, 07:51:00 am",
"content": "Quote from: rthorntn on November 12, 2024, 07:44:28 amYes or the stuff that JLC does not carry.Benno"
},
{
"post_id": "",
"author": "rthorntn",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "November 14, 2024, 11:57:53 pm",
"content": "Thanks all, a quick questions for the Aussies, where to get hobbyist amounts of quality paste in Oz, mail order from an Australian company, not wanting to go down the get to $60 for free delivery from overseas rabbit hole?"
},
{
"post_id": "",
"author": "brucehoult",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 15, 2024, 01:16:47 am",
"content": "https://www.jaycar.co.nz/solder-paste-smd-syringe-15g/p/NS3046https://www.jaycar.co.nz/lead-free-solder-paste-smd-syringe-10g/p/NS3048?? I assume you have one nearby you can walk into? Or mail order.Edit: oh, weird, there don't appear to be any in Mackay or Townsville or Cairns or even Adelaide.Here in NZ I've got one 35 min away in Whangarei, and also other small cities such as Tauranga, Rotorua, Wairoa, Napier, Hastings, New Plymouth, Palmerston North, Nelson, Blenheim, Dunedin, Invercargill. And several in each of the main three cities.I'm not sure if it's as many as there used to be DSE (they did take over some DSE shops in both countries), but it's a lot."
},
{
"post_id": "",
"author": "rthorntn",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "November 15, 2024, 01:57:54 am",
"content": "Thanks, so the Jaycar stuff is alright, is the price OK for that quantity?"
},
{
"post_id": "",
"author": "brucehoult",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 15, 2024, 02:11:13 am",
"content": "Price? No idea. Probably more than buying overseas, but then I'd imagine for most hobbyists their $20 of solder paste will time expire with some (even most) unused, so it's more of a (bi)annual cost than a per ml one.And, as one of those descriptions says, they get it in bulk from a local supplier and keep it in a fridge in the store, which is an advantage over importing it yourself."
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 16, 2024, 03:58:29 pm",
"content": "GC10 used to be the highest quality solder paste around, with a pot life of several years without refrigeration. I forgot the brand (Heller? Loctite?), it also got sold to some other company.But that was years ago. Back then it was exceptional, but apparently there are also other brands these days with a similar pot life."
},
{
"post_id": "",
"author": "awakephd",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 20, 2024, 02:12:37 am",
"content": "I don't know what the brand is, but I am still using some solder paste (in a \"syringe\") that I got 5 years ago - still works just fine. I keep it double-bagged in the refrigerator between uses."
}
] |
2025-10-17T16:27:31.987284
| 15
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(audio-preamp)-capacitor-question/
|
[Audio Preamp] - Capacitor question? - Page 1
|
[
{
"post_id": "",
"author": "ElectricGuy",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 06, 2014, 10:12:01 pm",
"content": "Hi all;I understand most of this schematic, but i don't know the purpose of the C7?What is the difference between using C7 or a direct short between R2 and R8?Thank you!"
},
{
"post_id": "",
"author": "grumpydoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2014, 10:15:04 pm",
"content": "It limits the DC gain of the stage to 1"
},
{
"post_id": "",
"author": "w2aew",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2014, 10:15:45 pm",
"content": "C7 makes the DC gain unity, such that the DC operating point (and output quiescent point) is established by the R6-R7 votlage divider. For AC signals, C7 looks like a near short, so the AC gain is determined by resistors."
},
{
"post_id": "",
"author": "ElectricGuy",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 06, 2014, 10:39:03 pm",
"content": "HI«i;Thank you both for the answers. So if i understand, C7 don't amplifie the DC voltage, only the AC voltage by 6 in this case, right?How can i calculate the value of that capacitor?"
},
{
"post_id": "",
"author": "Richard Crowley",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 07, 2014, 12:19:30 am",
"content": "C7 does not \"amplify\" anything. The gain comes from the op-amp, IC1B.As others have observed, the addition of C7 into that feedback voltage divider means that AC signals will be attenuated by the voltage divider (R2/R8), and thus make the op-amp work harder to equalize the differential inputs. i.e. the opamp will AMPLIFY the AC signal.However, at DC, there is no path to ground, so the opamp is limited to unity gain for DC signals. That is exactly what we want in an AC (audio) amplifier. We don't want any extra DC coming out of the output.But note that there is ANOTHER function of C7 in this particular case.Since this circuit has only a unipolar power supply, they are using that other voltage divider, R6/R7 to create an artificial ground for the opamp.But since the voltage divider R2/R8 is connected to \"real ground\", that would create quite an offset in the output.So C7 is also used to compensate for this difference in ground references.You can calculate the value of C7 from the requirement of what the low frequency response of amplifier should be.Roughly the 3dB down point is where the \"reactance\" of the capacitor equals 12K (R2 and R8 in series)For example, a 0.5 uF capactor would make the gain of the amplifier roll off by 3dB at 26 Hz.http://www.calculatoredge.com/enggcalc/Resistance-Frequency-Capacitance.htm"
},
{
"post_id": "",
"author": "ElectricGuy",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 07, 2014, 12:56:30 am",
"content": "Ok, i understand.I know that C7 doesn't amplify... i write wrong.Tank you for the link too."
},
{
"post_id": "",
"author": "Syntax_Error",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 07, 2014, 03:05:33 am",
"content": "Yes, thank you for the detailed technical responses. I just wanted to point out that there are many lurkers here who benefit and learn from the more advanced members' conversations here, and I thank you for that."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 07, 2014, 04:14:56 am",
"content": "Quote from: Richard Crowley on October 07, 2014, 12:19:30 amThat is not the number I end up with. The capacitor and R8 operate into the operational amplifier's virtual ground (which follows the non-inverting input) so they cannot see R2. Just calculating the non-inverting gain yields a 3 dB point with a 0.5 uF capacitor of 290 Hz instead of 26 Hz although because the amplifier is non-inverting and has a gain of 1 + R2/R8, the phase is not 45 degrees at that point.Or maybe I have too much blood circulating in my caffeine."
}
] |
2025-10-17T19:54:18.043099
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(aus)-second-hand-test-gear-for-setting-up-a-home-lab/
|
(AUS) Second hand test gear for setting up a home lab? - Page 1
|
[
{
"post_id": "",
"author": "Drewboy",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 16, 2014, 07:58:53 am",
"content": "Hi,First time poster, but have been very much enjoying the eev blog and forum for a year or so now. I'm also a second year EE student interested in setting up a home lab.I found this old thread:https://www.eevblog.com/forum/chat/electronics-flea-markets-swap-meets-(australia)/Wyong Field day was mentioned, has anyone been recently? Would it be a good place to pick up an analogue scope/benchtop power supply/waveform gen/DMM etc? I'm not into amateur radio but love old electronics.Generally, I haven't had much luck looking for second hand stuff online (eBay mostly), there appears to be a lot of speculators on oscilloscopes especially ($$$, powers up, not tested further, sold as is), also shipping to Australia usually kills any reasonably priced listings. I would love to hear how people within Australia go about sourcing their gear and any tips they might have (auctions, second hand dealers, pawn shops, tender centre, flea markets etc. Do any of these work?).After a lot of searching so far the best option seems to be cheap-o new equipment (e.g. Rigol scope, mastech power supply) it just seems a shame, I rather like older electronics and the idea of reusing stuff that might otherwise end up in landfill or gather dust appeals to me."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 08:18:50 am",
"content": "The Wyong field day is next weekend!See my previous video for the types of gear there. They didn't seem that cheap to me, but at least you can scratch'n'sniff before you buy.I'm thinking about taking all my auction gear down and trying to flog it, but not sure if it's worth the effort.I get most of my stuff on ebay, you just have to hang out for overseas seller who offer cheap international shipping."
},
{
"post_id": "",
"author": "Drewboy",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 16, 2014, 08:28:49 am",
"content": "I was quite surprised. I sat down to look at what electronics markets exist in Australia and lo and behold the only one in Australia is on next weekend! I too am trying to gauge if it will be worth it, I'm based in northern NSW (5 mins shy of the Qld border) so the travel time would be non trivial."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 08:34:28 am",
"content": "Quote from: Drewboy on February 16, 2014, 08:28:49 amMake up your mind:I expect similar again this time. I'm told it's not as good as it once was. You have to get there early for the flea market / car boot sales. They are all mostly gone by midday.Realistically the petrol will probably cost the same as shipping from an international seller."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 08:48:56 am",
"content": "Quote from: Drewboy on February 16, 2014, 07:58:53 amThe majority are silly priced, but some are reasonable like this:http://www.ebay.com.au/itm/Tektronix-2445-Analog-Oscilloscope-/231149951559?pt=BI_Oscilloscopes&hash=item35d19c5a47&_uhb=1The weak aussie dollar does not help."
},
{
"post_id": "",
"author": "VK5RC",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 09:04:03 am",
"content": "I have had moderate success with eBay, I have stuck with gear that I can get full manuals, schematics. Unless really cheap avoid 'as is'.The manual requirements tends to put me in with HP/Agilent, often their gear 5-10yr old that is still going well but depreciated a fair bit. You have to be patient at times and quick off the mark at others."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 16, 2014, 09:12:04 am",
"content": "Quote from: EEVblog on February 16, 2014, 08:48:56 amYou think the AUD is weak? Try the ZAR. 11 to 1 and worsening."
},
{
"post_id": "",
"author": "Drewboy",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 16, 2014, 09:27:58 am",
"content": "Thanks Dave and VK5RC. Regarding eBay and buying internationally, have either of you had any experience with eBay's \"Global Shipping Program\"? I believe US sellers ship locally to a processing centre in Kentucky who then handles the forwarding of it internationally, opening up \"US only\" sales to the rest of the world.I've heard of it being a rort for sending to some countries (excessive customs fees) but apparently it results in quite reasonable cost shipping to Australia. If you have any firsthand experience I'd love to hear about it (Price, timeframes etc)."
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 09:42:25 am",
"content": "Quote from: Drewboy on February 16, 2014, 08:28:49 amThere's more than one ham swap meet in Aus, but unless you know where to look you'd struggle to know it (e.g. there used to be one at a local school every year, yet neither my partner who works there nor my father who lives a couple of streets away had ever heard about it). There's a reasonable, but probably incomplete, list for SE Qld / N NSW on theVK4ICEwebsite (scroll down).Apologies in advance to any hams I may upset, but I've gotta say I've never been impressed with either the range of stuff for sale or the people selling it (e.g. the one time I did find a reasonable bargain the guy refused to sell it to me because I was neither a ham nor known to anyone there!). They're not all like that - I do know a few active hams locally who are good people - but that kind of attitude does seem to be rather prevalent, at least amongst the local groups.All in all, waiting and watching eBay for a bargain is probably a better bet."
},
{
"post_id": "",
"author": "Drewboy",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 16, 2014, 10:08:23 am",
"content": "Tac Eht Xilef, thanks for the additional info, very much appreciated. I thought it was a little odd that I couldn't find any others, turns out they're not much into SEO so I didn't finding them with a cursory google.I think I might forego the 8hr trip to Wyong and try some of these more local meetups instead. As suggested, will keep my eye on eBay too."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 10:09:20 am",
"content": "Quote from: Drewboy on February 16, 2014, 09:27:58 amNo idea about the ebay program, but I have a US address through a shipping company for rare stuff. But the shipping is very expensive so you have to be desperate.I just search for the lowest price shipping (usually USPS I believe) and they ship it. Never had an issue."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 16, 2014, 10:34:18 am",
"content": "Quote from: Tac Eht Xilef on February 16, 2014, 09:42:25 amWith respect,itisa Hamfest,& the majority of stuff will be Transceivers & the like.Test Equipment is quite peripheral,so there normally won't be tables full of Oscilloscopes.etc.As I said on another occasion,it's like a River's ad---\"There may be lots,there may be none!\"The Perth Hamfest often has non-Ham people turn up,& the only case where you may be queried is if you are looking to buy Transmitting equipment & don't have a licence.I bought my Tek 7613 at the Hamfest a few years back for $135---I haven't really seen anything on eBay.au which was as good a deal,especially when you factor in postage from the ES.There are a couple of organisations on eBay.au who post ludicrous prices for old gear---for example,$350 for a BWD 509!"
},
{
"post_id": "",
"author": "VK5RC",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 10:45:28 am",
"content": "No idea about the eBay program as I have not used it.Yesterday I got a HP 6644 60V 3A PSU for 270 incl post. I was happy as it is still in production and for sale new at AUS ~2,000.fromhttp://stores.ebay.com.au/tekdragonstore/Bizarrely I think sometimes you get the best deals from a general electronics used dealer than some of the specific electronic T&M ones but the risk goes up with higher end equipment.Good Hunting."
},
{
"post_id": "",
"author": "nowlan",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 16, 2014, 11:01:54 am",
"content": "I think hat global shipping is a tie in with fedex or ups & ebay. My mother has used it once, where the parcel was destroyed at request of shipper. Neither she or seller knew anything about it, until we queried tracking message.She ended up contacting paypal for non delivery. Seller needs to chase up insurance via ebay etc.I suspect that if the item is over 1,000$aud they know they need to collect duty, and will bill you administrative fee on top.Ive noticed amazon now collects this upfront too.---Not sure what happens to surplus equipment in Australia. Ive only seen the local tafe, and not sure they ever throw things away. Suspect a lot of equipment just sits in storage as spares etc.Its not like computer parts, which are leased or turn over often every few years. Good reliable equipment seems to keep on ticking, or be repaired."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 12:03:39 pm",
"content": "Quote from: vk6zgo on February 16, 2014, 10:34:18 amThere are many people in Oz who simply won't buy from overseas, so gear always goes for more here. But yeah, there are some silly prices.Like this old 5000 series Rigol for $500:http://www.ebay.com.au/itm/RIGOL-Digital-Oscilloscope-DS-5102MA-/301097828242The classic 1052E is better, smaller, and cheaper brand new.I've made a decent amount of money over the years buying and selling test gear on ebay.I usually buy from overseas and then resell locally.I have a TDS220 listed for $199 at the moment. A pretty reasonable price I think, but I know it will go for more, the going rate here seems to be about $350 and there are currently 23 watchers."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 12:07:21 pm",
"content": "For analog fans, this nice Tek 2445 is going for $299 in Oz, that's US prices.http://www.ebay.com.au/itm/Tektronix-2445-Oscilloscope-4-CH-150-MHz-Tested-Working-/291079369751"
},
{
"post_id": "",
"author": "Drewboy",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 16, 2014, 12:17:31 pm",
"content": "Quote from: EEVblog on February 16, 2014, 12:07:21 pmI was considering that one. Not sure what to make of the \"horizontal deflection is slightly unstable\" detail in the product description though, guess thats where the \"scratch & sniff\" element of buying in person comes in handy."
},
{
"post_id": "",
"author": "metalphreak",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 16, 2014, 12:56:44 pm",
"content": "Quote from: Drewboy on February 16, 2014, 09:27:58 amIt's through a company called Pitney Bowes. I had a bunch of reasonably heavy server power supplies shipped through it and the prices were very reasonable. Shipment for the international part of it was pretty quick as well. When you pay via paypal, you actually pay the US shipper for the item price + local US shipping the pitney bowes distribution hub. The rest of the payment goes directly to PB for the international shipping.I actually had two shipments of PSUs from two different sellers, and it was a great experience overall. I'd definitely recommend it for Aussie buyers. You get proper package tracking the whole way from seller to PB to you."
},
{
"post_id": "",
"author": "peter.mitchell",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 16, 2014, 12:58:39 pm",
"content": "I watched this one go the other day Dave;TDS1012B, I reckon if that fella can get $305 for that, looking like that, $350 should be cakewalk for you Stone the Flamin' Crows! You can get a Brand SpankinDS1052Efor $340 Delivered!"
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 16, 2014, 01:49:03 pm",
"content": "Quote from: vk6zgo on February 16, 2014, 10:34:18 amWithout wishing to derail the thread further, I was thinking of the many times over the years I've gone to local hamfests/boot sales looking for old transcievers to part out, receivers to repair and use, radio test gear, and to just browse and maybe pick up some random connectors, old books and manuals, or other bits and bobs. What I found was retail dealers selling new stuff, people selling second-hand stuff at not very good prices, and a lot of utter junk (e.g. gear totally stripped of anything worthwhile) at ridiculous prices. But, as I said, that was local hamfests - not anything big like Wyong.Quote from: vk6zgo on February 16, 2014, 10:34:18 amIn the case I mentioned it was an old RF millivoltmeter (with probe, which is why I was interested). And it wasn't a query, it was a flat-out \"I'm not selling that unless you can prove you're licenced or someone here will vouch for you\" as I picked it up to look at it...I dunno, maybe I'd just struck someone having a bad day. It happens. All I can say is that case - and more than a few others like it over the years - have left a bad taste in my mouth.Not looking for an argument - as I said before I know plenty of hams who aren't like that - and this really isn't the right place for an extended discussion.Drewboy, remember to watch for mis-spellings too. Picked up a nice R5000 for stupid-cheap a couple of years ago because someone couldn't spell \"Kenwood\", \"communications\", or \"receiver\""
},
{
"post_id": "",
"author": "GreyWoolfe",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 17, 2014, 12:08:43 am",
"content": "Tac, I could understand his comment if you were trying to buy a transceiver. But a millivolt meter? That's just a cranky old ham, regardless of his age. Unfortunately, not too uncommon these days. Common civility, along with common sense, seems to have left the building. I wouldn't be surprised if he didn't go home with it and grumbled that he didn't sell enough. I won't sell a transmitter/transceiver to anyone not licensed, but test gear? As long as your money is the right color and we can agree on a price, we will do the deal."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 17, 2014, 12:24:49 am",
"content": "Quote from: wilfred on February 16, 2014, 12:38:37 pmI've never really done that, but it does make sense in some cases."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 17, 2014, 12:26:28 am",
"content": "Quote from: peter.mitchell on February 16, 2014, 12:58:39 pmMy last TDS220 went for $342"
},
{
"post_id": "",
"author": "AlfBaz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 17, 2014, 02:26:05 am",
"content": "Quote from: EEVblog on February 17, 2014, 12:24:49 amI was in the market for one of those CNC routers, they were all going for 1200 or so dollars \"Buy it now\". Somebone did the .99c thing and it ended up going for just over 2 grand"
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 17, 2014, 03:35:19 am",
"content": "Ok, 99cent auction:http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=271404227340"
},
{
"post_id": "",
"author": "pickle9000",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 17, 2014, 03:53:06 am",
"content": "MmmnnmmMMmm Crusty, great meter though. It was shiny when I bought it, still use it daily."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 17, 2014, 03:55:41 am",
"content": "Quote from: EEVblog on February 17, 2014, 03:35:19 amWell, it only took 5 minutes before someone bid."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 17, 2014, 06:54:10 am",
"content": "Quote from: Tac Eht XilefSome Hams (more commonly in the USA than in this country),get quite \"aggro\" at the thought of people buying radios,parting them out then selling the parts.Admittedly,there are some \"vultures\" who make a big thing of this,buying radios in perfect operating condition & selling the parts at a substantial \"markup\".This has two effects:(1) It reduces the number of functional secondhand radios on the market,pushing up prices.(2) It makes refurbishing of existing radios more expensive.I'm not suggesting that you are one of the \"vultures\" referred to,but maybe some people have incorrectly assumed you are.Demanding you show a Ham licence is a bit silly,as some of the \"vultures\" are licenced Hams."
},
{
"post_id": "",
"author": "Weez",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "February 17, 2014, 01:55:01 pm",
"content": "Quote from: Tac Eht XilefAnd, it doesn't really prove anything anyway, since it's very easy to get a license nowadays."
},
{
"post_id": "",
"author": "jokkydee",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "July 01, 2014, 02:32:28 am",
"content": "Quote from: nowlan on February 16, 2014, 11:01:54 amI used to work for Codan Limited (Adelaide based electronics manufacturer), and they would have internal auctions for all their surplus equipment. I picked up an old analog scope for $2 and put it straight on ebay. Also picked up a vintage HF/Audio signal generator for $3, served me well for a few years and soon I'll be putting it on ebay in coming weeks. They also auctioned off soldering irons, drill presses, laptops, you name it. It was anabsolutegold mine."
}
] |
2025-10-17T19:59:41.764061
| 30
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(avr-components)-need-help-regarding-nimh-aaa-charger/
|
[AVR / Components] Need help regarding NiMH AAA charger - Page 1
|
[
{
"post_id": "",
"author": "Nitrus",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 07, 2017, 04:00:23 am",
"content": "Hi everyone,I've been trying my hand at making a NiMH charger (I'll explain my project below).I know the topic has been extensively discussed to hell and back, however surprisingly there areveryfew open source circuits available online.My requirements are that it needs to be capable of charging two AAA cells @900mAh each (wired in series), to run off USB +5V, and to be reasonably fast (3, 3.5 hours is acceptable).I foundthis one charger circuitand I think it will be suitable for my purposes, however there are a few things in it that I can't wrap my mind around. I tried asking the author however I don't think he's active on that blog anymore.https://arduinoelectronics.wordpress.com/2012/04/20/smart-nimh-battery-power-charger-based-on-attiny85So, if you've taken a look already, you would have seen the Red LED that's used to provide constant current. I'd venture to say that it is a neat trick (even if I disagree with it).Here come my questions:1) Can anyone explain to me how that Red LED constant current thing works? I understand as far as forward voltage drop, but not the part about the constant current, not really. I've remade the schematic in a SPICE simulation environment and that LED never blinks for me, which is clearly different from the author's video. I get pulsed current, but not the blink.2) There is a Schottky below the PNP. Is there any other function to it other than to protect the components behind it from the battery connection?3) Can the circuit work as-is with +5V, instead of the +12V specified in the schematic? The author says it was designed for 6 cells @2500mAh, however I think it can work as-is for my requirements as well: 2xAAA cells @1800mAh. I only got rid of the linear v.regulator part of the circuit, everything before the Red LED, and replaced the 12V source with 5V. I'd appreciate if anyone can make the corrections (if any), or better yet teach me about what needs to be corrected.Finally, if anyone can link me a better circuit, I'll gladly take it. Any advice is welcome at this point, I've rarely done anything to do with NiMH/NiCd charging before, other than some research in the past few days.---My application is as follows: I need a small circuit to implement within the enclosure of a joystick controller that has two built-in AAA batteries. Ideally I would have wanted to replace those with LiPos and have a single-chip charging setup, but the problem is I can't bloody fit any decent capacity LiPOs in the casing, I'm very limited in terms of space. The current draw of the joystick is about 15mA, which is quite a lot for e.g. those small 250-300mAh LiPOs. It would be discharged in a matter of hours...So, I'm stuck with NiMH AAAs, and need an intelligent charging solution for the specific situation.I'm not afraid of AVR, I've got a few different types at my disposal.Thank you all in advance for anything you can throw at me."
},
{
"post_id": "",
"author": "tron9000",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 07, 2017, 09:43:38 am",
"content": "FYI - introduce yourself first - go do that now:https://www.eevblog.com/forum/chat/new-member-please-introduce-yourself/?topicseenI'll give it a shot: The LED is acting like a zener: applying a fixed \"regulated\" voltage. The LED has a forward voltage of ~2V and the PN junction of Q1 has a drop of ~0.7V. This means that there must be about 1.3V across R3. Current therefore through Q1 and thus into the batteries should be1.3/R3and should be constant with respect to the LED voltage. Build it and try it and change the LED colour and you should see a different current through Q1Nope - you hit the nail on the headNope"
},
{
"post_id": "",
"author": "Nitrus",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 07, 2017, 12:31:47 pm",
"content": "Quote from: tron9000 on February 07, 2017, 09:43:38 amRight, I've gone and done thatThanks for your explanation on 1), it confirmed some of the things I was thinking, I'll mull it over some more. I didn't have anything like the darlington on hand, and only BC517 for now so I'm waiting for those to arrive, which may take a while since when I order components like these, I order in bulk of 50s or 100s from ebay or aliexpress. (more legit places rarely deliver to my country, or delivery costs 10 times as much as the components)To be perfectly honest I'll be getting surface mounts components sooner than through hole ones, I put an order for typical kit stock of caps and resistors before hand, because I was hoping to design and make it as small as I can.As for 3), you mean it cannot work as-is, or you have no corrections/suggestions?Thanks for the help so far!"
},
{
"post_id": "",
"author": "tron9000",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 07, 2017, 02:38:58 pm",
"content": "well maybe just, actually. You need a supply greater than the 2 charged AAA's + one schottky diode drop + Vdrop across R3"
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 08, 2017, 09:17:33 am",
"content": "Quote from: tron9000 on February 07, 2017, 02:38:58 pmDon't forget the Vce of the transistor. It's a darlington so this figure is likely to be quite high, certainly high enough to prevent this working. It should be possible to use a normal NPN to lower Vce with some circuit adjustments.Also the current source is configured for 1.5A to 2.5A depending on LED etc. which may be a problem for some USB ports (esp. older laptops) and is likely too high for AAA cells anyway."
},
{
"post_id": "",
"author": "Nitrus",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 08, 2017, 10:33:48 am",
"content": "Quote from: mikerj on February 08, 2017, 09:17:33 amThat's true. I've read somewhere that charge rate for AAA NiMH is 400mA tops (1A for AA), so I should be able to find suitable replacements easily, hopefully.Quote from: mikerj on February 08, 2017, 09:17:33 amYes, USB 1.0 & 2.0 are rated at 500mA and USB 3.0 at 900 (although I wouldn't push my luck).Anyways, where is it configured for 1.5A to 2.5A? To me it looks like it's going to scale down with the Voltage, not sure... Any pointers?EDIT: I've added my modified schematic, at least what Ithinkwould be OK. I could be dead wrong. P.S. The transistor's Vce seems to be not that bad."
},
{
"post_id": "",
"author": "tron9000",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 08, 2017, 12:34:11 pm",
"content": "Quote from: mikerj on February 08, 2017, 09:17:33 amYeh no Vce no workie!I think its darlington so the amount of base current needed doesn't affect the Vf of the LED maybe. hfe of 1000 for TIP127 Vs hfe of 10 for a TIP32 say means 100 times increase in base. This would give to a greater voltage rise across R1 and affect Vf of LED."
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 08, 2017, 10:09:53 pm",
"content": "Quote from: Nitrus on February 08, 2017, 10:33:48 amIt's a constant current circuit, the whole point is that the current should remain fixed irrespective of voltage. In this case it's a fairly crude current source so there will be a little variation, but the current won't scale with voltage in the way you are hoping.The current is set by the voltage developed across R3, the 0.3 ohm resistor. e.g. given a 2v Vf LED and 0.7v drop across each Vbe junction you get I=(2-0.7-0.7)/0.3 = 2 Amps. To reduce the current, increase the value of R3."
},
{
"post_id": "",
"author": "Nitrus",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 08, 2017, 10:38:26 pm",
"content": "Quote from: mikerj on February 08, 2017, 10:09:53 pmOhhh, I see! Thanks, that makes a lot of sense!Hmm, I think most Red LEDs that I can get my hands on will have a 2.2 Vf, so I'll have to get a 1% resistor that will be in the 1Ohm range: ( 2.2 - 0.7 - 0.7 ) / 1.0 = 0.8 Amps.Provided that the rest of the circuit stays the same, I think this solved my dilemma.Finally, one last question, since I've very little experience with NiMH. Well with charging circuits in general really.As I mentioned previously, I've got 2xAAA that supposedly can be charged at 500mA. I'm wiring them in series because I need upwards of 2.4 Volts, so essentially like a two cell pack.Do I charge them with 500mA or with 1000mA?My guess is 1000mA, but I'd rather be safe than sorry"
},
{
"post_id": "",
"author": "Audioguru",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 09, 2017, 01:51:15 am",
"content": "Two batteries in series have the same 500mA of current.A red LED has a range of voltage from maybe 1.8V to about 2.2V. You cannot order a \"2.2V\" LED, you get whatever is available and it might be only 1.8V.Transistors also have a range of base-emitter voltage and collector to emitter saturation voltage. Again you get whatever is available.So the very simple circuit might charge the battery with almost no current or averyhigh current."
},
{
"post_id": "",
"author": "Nitrus",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 09, 2017, 02:38:45 am",
"content": "You know, that first sentence you said just dawned realization on me:Series. Only adding the voltage... {gears grinding} mAh will stay the same (facepalm)Without thinking I'd foolishly set myself on a path that I somehow imagined would get me more juice... 😧I will still probably build the circuit. It's going to be useful to have a semi-intelligent NiMH charger.However, for my application I'm thinking I may go down the Li-ion route and get two CR2/15270 cells and wire them in parallel, then make them go through a v.reg.Charging solutions will be a lot simpler then.Discharge rates may be a bother but ultimately it's going to be a simpler implementation...Then again AAAs will always be cheaper if I need to replace them further down the line... Bah!I guess no matter which route I go, with my form-factor I wouldn't be able to get much more than 1200mAh, tops. (If I buy better rechargeable AAAs, or two 600mAh 15270s)Thank you all for the wonderfully educational experience, cheers!"
},
{
"post_id": "",
"author": "eugenenine",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 09, 2017, 12:37:04 pm",
"content": "Quote from: Nitrus on February 07, 2017, 04:00:23 amTi, Maxim, etc all make NiMH charging IC's with reference designs you can use."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 09, 2017, 10:27:09 pm",
"content": "Quote from: Nitrus on February 07, 2017, 04:00:23 amThe voltage across R3 is roughly Vled - 2Vbe so about 2 - 1.4 = 0.6 volts so with a 0.3 ohm resistor, 2 amps.On advantage of using the LED this way is that its temperature coefficient roughly matches the temperature coefficient of one of the transistor Vbe junctions. If a bipolar transistor was used instead of a Darlington, then the temperature matching would be very good.QuoteIn the design shown in the link, the diode is necessary because otherwise the 7.2 volts from the charged battery would likely flow back through the collector-base junction through the LED and also through the emitter-base junction of the transistor when the input supply is removed.QuoteSaturation of the Darlington transistor will be about Vbe + Vce = 0.7 + 0.35 = 1.05 volts. The resistor has about 0.6 volts across it. So the total drop is 1.65 volts leaving 3.35 volts to charge two NiMH cells in series. That could work but does not leave much margin.The 2.4 to 2.8 volts from 2 NiCd cells is low enough that the reverse protection diode would not be needed.QuoteThe charging current for NiMH and NiCd batteries does not need to be that exact. Use a high side transistor switch and rely on the 5 volt supply to be stable and use a resistor to limit the current. Subtract the charged battery voltage and transistor saturation voltage from 5 volts to find the voltage across the resistor and set it accordingly for the desired current. USB limits you to 500mA so a single PNP bipolar transistor instead of a Darlington could be used."
},
{
"post_id": "",
"author": "Nitrus",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 10, 2017, 12:10:30 pm",
"content": "@David yes, I've since found out that the circuit could be minimized and stripped significantly when used with only 2xAAA batteries. For example, there is a wide choice of bipolar transistors that could be used at such small currents, and as you say the diode is not even needed with this application.Thank you very much for the thorough explanation!"
},
{
"post_id": "",
"author": "tron9000",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 13, 2017, 09:20:19 am",
"content": "Something I would like to know: does the example program use negative delta V detection to determine end of charge or is that not essential?"
},
{
"post_id": "",
"author": "Nitrus",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 13, 2017, 09:31:40 am",
"content": "Quote from: tron9000 on February 13, 2017, 09:20:19 amI believe so, the author mentions it in the text:\"We need to constantly read the voltage of the battery being charged, and when there will be a maximum peak voltage followed by a sudden drop of about 20mV, the battery may be considered charged. This phenomenon (called Negative Delta V) is related to the chemistry of this type of battery, and allows to establish precisely the right moment to terminate charging.\"In the code it's covered (a bit convoluted) in the voltread() function, line 62 and onwards."
}
] |
2025-10-17T19:03:19.361297
| 16
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(cheap)-esr-meter-for-beginner-suggestions/
|
(cheap) ESR Meter for beginner, suggestions? - Page 1
|
[
{
"post_id": "",
"author": "LeWidget",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 27, 2015, 01:57:55 pm",
"content": "hey guys,I was wondering if anyone had suggestions on cheapish ESR meters for basic repairs ? I've looked around and two that I've read about are at least $100usd + shipping.. which seems a lot, not sure if that's what they run for.http://shop.anatekcorp.com/index.php?src=directory&view=products&srctype=detail&refno=2&category=Component%20Analyzershttp://www.ebay.com.au/itm/DER-EE-DE-5000-High-Accuracy-Handheld-LCR-Meter-New-from-Japan-Free-ShIpping-/151122560024?pt=LH_DefaultDomain_0&hash=item232f9b4418(Not sure if an LCR meter would benefit me or not)I have a MM (https://www.toolmart.com.au/measuring-tools/qm1548.html) which does Capacitance, though never used it, nor know of its accuracy. an ESR that measures both ESR/Capacitance would be neat I guess, but probably not essentialhttp://www.peakelec.co.uk/acatalog/jz_esr70.htmlHear the above wasn't too good and pricy for what is was.I also came across this one in ebay,http://www.ebay.com.au/itm/ESR-V5-ESR-Capacitor-Tester-Internal-Resistance-Meter-Test-In-Circuit-Online-NEW-/331330272460?hash=item4d24d2bcccthough a cheap chinese model, not sure how accurate it would be. It also says it only measures upto 2000uF, is that considered low? Would there be higher rated caps in smaller devices?I was considering learning repairs for basic electronic items (monitors, PSUs, speakers etc..), but didnt want to waste money on something that might be of no benefit.I have seen some schematics on making one.. but at this stage I think it's a bit much for me and I don't think I have the proper means to calibrate it.Any suggestions would be super,Thanks,"
},
{
"post_id": "",
"author": "GreyWoolfe",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 27, 2015, 03:56:40 pm",
"content": "The DER EE DE-5000 is a nice unit. The best bargain is the get it with the TL-21, TL-22 and TL-23:http://www.ebay.com.au/itm/DER-EE-DE-5000-High-Accuracy-Handheld-LCR-Meter-with-TL-21-TL-22-TL-23-/261980180124?hash=item3cff3c4e9cPedroDaGr8 did a review on it here-https://www.eevblog.com/forum/testgear/der-ee-de-5000-unboxing-and-teardown/I also have one and it is very useful. I would pull the plug and get with the extras."
},
{
"post_id": "",
"author": "Mephitus",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 27, 2015, 04:06:22 pm",
"content": "Might I recommend the 5 transistor ESR?https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/msg171364/#msg171364"
},
{
"post_id": "",
"author": "kripton2035",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2015, 04:29:42 pm",
"content": "build yourself one, it's easy and you learn from thatplenty of schematics on my repository (address below)"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2015, 06:32:12 pm",
"content": "I have one of these...http://www.ebay.co.uk/itm/Auto-Range-In-Circuit-ESR-Capacitor-Meter-Tester-Up-to-0-001-to-100R-MESR100-UK-/311001050791?hash=item48691b6ea7It works well and has good resolution. It measures at 100kHz with (approximate) sine wave - I don't remember paying that much for it though.Note that it only measures ESR, there's no capacitance measurement function. The clips are not Kelvin connection though so it doesn't distinguish contact resistance from ESR at the milliOhm level but the Zero button takes out lead resistance.and most of the contact resistance if you zero it with both clips on the same capacitor lead first.I agree, a basic one is a good beginners project for basic go / no-go testing where you're not trying to check low ESR caps against manufacturers' specs."
},
{
"post_id": "",
"author": "michaeliv",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 27, 2015, 07:32:48 pm",
"content": "I have this and it works great. You don't get continuous measurement though, you have to hook up the component & press the button.http://www.aliexpress.com/item/Free-Shipping-New-1Pcs-Mega328-Transistor-Tester-Diode-Triode-Capacitance-ESR-Meter-MOS-PNP-NPN-L/1881144443.htmlhttp://www.ebay.com/itm/Mega328-ESR-Meter-LCR-Transistor-Tester-Diode-Triode-Capacitance-inductance-MOS-/281453993732?hash=item4187f71f04Accuracy is great ( better than my $50-$60 ish multimeter for SMD caps ).Measuring time is around 2s.It actually does an impressive job when recognizing components."
},
{
"post_id": "",
"author": "McBryce",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2015, 07:46:14 pm",
"content": "Take a look at the Peaktech LCR meters (3705, 3730 or 2175). They start at about €30 for the simplest version. They're obviously not \"highend\", but for occassional use and to find out whether you'd make use of one they are more than enough.McBryce."
},
{
"post_id": "",
"author": "AG6QR",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 28, 2015, 03:07:44 am",
"content": "I can endorse the Anatek Blue ESR meter, which I built from a kit. It's cheaper as a kit (80 vs 99), and the kit isn't hard to put together.That meter is basically a low ohm AC impedance meter. It works well for diagnosing failed caps, where precision isn't necessary. It works in-circuit, which is useful for service work. It is not a precision LCR meter, and doesn't pretend to be.It's good for those times when you have a failed circuit that used to work, and you kind of suspect bad caps. Without going into too detailed troubleshooting or tracing schematics, you can quickly check each electrolytic and see which ones need to be replaced."
},
{
"post_id": "",
"author": "kripton2035",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 28, 2015, 05:47:15 am",
"content": "Quote from: McBryce on July 27, 2015, 07:46:14 pmthese meters do not measure ESR. only R,C or L"
},
{
"post_id": "",
"author": "McBryce",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 28, 2015, 08:28:16 am",
"content": "Oops, doh! I went to get a link for the ESR meter I use (Peak Atlas 60) and got completely side tracked because I am looking for a cheap LCR meter for someone elseI think I'm going senile!Ok, then back to the original question... How about the Peak Atlas 60http://www.reichelt.de/?ARTICLE=81773&PROVID=2788&wt_mc=amc141526782519998&&gclid=CIOvk-iz_cYCFS3ItAodnK0MLQMcBryce... Heading off to find his medicine..."
},
{
"post_id": "",
"author": "oldway",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 28, 2015, 08:53:19 am",
"content": "Here, you will find a cheap and very good project of ESR meter by Jay_Diddy_B.It is fully protected and will not been damaged by loaded capacitors.Sadly, you must be aware that most of comercial ESR meter's are fragile and that they are easily damaged by loaded capacitors.https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/Another great application of such an ESR who will not be damaged by DC apply voltage is to do a quick test of all kinds of battery measuring their internal resistance."
},
{
"post_id": "",
"author": "LeWidget",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 29, 2015, 12:22:51 pm",
"content": "Where do you get the PCB for the home-built ESR meters, such as the one by 'Jay_Diddy_B' or the kits listed on 'Kripton2035' site ? I think at this stage, that's the main problem compared to ordering a pre-built one.I had a look at the 'Peak Atlas 60' but at around $140.. seems a bit pricy for me at this stage.The cheap one that cost <$20 seem tempting, especially if they do the job.. only thing is they dont seem to be in-circuit, which is a bummer. In-Circuit seems like it would savealotof time.. especially if needing to test multiple components...Next one im leaning towards is the MESR-100http://www.ebay.com.au/itm/Auto-Range-In-Circuit-ESR-Capacitor-Meter-Tester-Up-to-0-001-to-100R-MESR100-AU-/121376072454?hash=item1c4293e306Though @ $80.. are there any that sit in-between the $20 - $80 range that can do in-circuit? Even ones that are homemade (assuming I can get a PCB) ?Thanks again guys, much appreciated"
},
{
"post_id": "",
"author": "McBryce",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2015, 12:32:21 pm",
"content": "I wouldn't put so much value on In-circuit ESR measurement. In many realworld cases there will be parallel components on the board that will cause inaccurate (or completely wrong) ESR readings even in the device claims it can measure in-circuit.McBryce."
},
{
"post_id": "",
"author": "JackP",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 29, 2015, 12:39:20 pm",
"content": "Watch SDG electronics' review on the Peak ESR metre (and keep the content coming for us subs!)."
},
{
"post_id": "",
"author": "AG6QR",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 29, 2015, 02:26:01 pm",
"content": "Quote from: McBryce on July 29, 2015, 12:32:21 pmNot as often as you might think. A reasonable in-circuit ESR meter keeps the test voltage low enough to avoid turning on any semiconductor junctions, so they appear as open circuit. We're only left with passive components directly in parallel with the capacitors that might affect readings. The ESR should be on the order of Ohms, maybe tens of Ohms, depending on capacitance. Anything with impedance an order of magnitude higher in parallel won't be significant. There's rarely a reason to put a very small resistor in parallel with a capacitor. A larger value bleed resistor in parallel with a capacitor will have negligible effect.Sometimes two or more capacitors will be placed in parallel. This is a situation where an in-circuit ESR meter can't see the ESR of each capacitor individually, but can only see the ESR of the combination. That can be a problem, and may call for desoldering one leg of a cap.An inductor directly in parallel with a capacitor may have a low enough impedance at the test frequency to be misleading, as well, in a tank circuit that's designed to resonate at something near the test frequency or higher.But most circuits don't have these situations."
},
{
"post_id": "",
"author": "McBryce",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2015, 07:22:23 pm",
"content": "Quote from: AG6QR on July 29, 2015, 02:26:01 pmAll true and correct, but I've had so many situations where I couldn't trust the reported values, that I tend to unsolder one leg every time now, just to be sure. In most cases it was a repair and some other component had failed to short or almost short. So I no longer consider in-circuit testing to be an important factor.McBryce."
}
] |
2025-10-17T19:36:26.703282
| 16
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(design)-how-to-drive-many-high-current-out-of-gpios-(esp32)/
|
[Design] How to drive many "high" current relays and LED out of GPIOs (ESP32) - Page 1
|
[
{
"post_id": "",
"author": "crgarcia",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 01, 2023, 04:37:45 pm",
"content": "Hi,I want to build a panel that has:- 8 push buttons (like this one:https://m.media-amazon.com/images/I/51+XvhFq5FL._SL1100_.jpg)- 8 5V LEDs (in the button, but controlled separately)- 8 relaysI want to control all that with an ESP32.The relays are in a modules,triggered on LOW, similar to this one:Relays:I have some 74HV595 shift register, that I thought I could use to control the relays.My concern is that the relays might get triggered while the microcontroller is booting. To solve that, I was planning to add a transistor to a GPIO to control the relays power supply (JD-VCC) (the PN2222A in the schematics bellow)Leds:I was thinking on adding a ULN2003 in series to the 74HV595, that would allow me to handle more current and voltageMy conceptual design:Since I am a self-tough beginner on electronics (pretty dangerous combination)... What do you think on that design?Is there a better way to make sure the relays are all off while the microcontroller is booting?Thank you!"
},
{
"post_id": "",
"author": "Kim Christensen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2023, 04:59:37 pm",
"content": "Isn't the ESP32 a 3.3V device? The way you've got Q1 wired means that the relay module would receive less than 2.6V because of Q1's 0.7V Vbe drop...Another way of disabling the relays would be to drive pin 13 (-OE) of U2 high during boot and only shift it low once the data has been clocked into U2 and latched."
},
{
"post_id": "",
"author": "mishomvp",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "May 01, 2023, 09:48:39 pm",
"content": "See this schematichttps://kmpelectronics.eu/wp-content/uploads/2019/12/ProDINoESP32-ETHv02-Schematic.pdf"
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2023, 10:22:09 pm",
"content": "Place a pull-up resistor on the OE input to the HC595, and a transistor to pull it low when your MCU is ready. Remember a pull-down on the transistor base as well as a series base resistor. A small logic-level MOSFET sould also do the job."
}
] |
2025-10-17T16:55:14.426671
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(diy-serial-analog-duty-cycle-meter)-voltmeter-voltage-regulators-mcu-usb/
|
Finished: DIY serial analog duty cycle meter (for CPU and RAM load) - Page 1
|
[
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 19, 2016, 11:58:38 am",
"content": "Hey there, i need some noob lube!I want to build aserial analog duty cycle meter.Its application would be a CPU load meter …like this:Core 2 Duo:Core i7 (w/ HT):Here's my idea (Plan A):The meter appliance will be connected via USB, and contain a USB-to-serial module (CH340)My OS of choice is Linux, so the software should be relatively easy: a shell script loop collects data (load per CPU core, as int 0-100) and dumps it (in CSV format, or such) to /dev/ttyUSBxAn MCU, probably an Arduino nano (ATmega328P), does some *magic* with the numbers and drives avoltage regulating black boxThe output of thevoltage regulating black boxis fed intothose panel meters(1 per core) …scale x10, 0V = 0% load, 10V = 100% loadBam, done, now i have moving needles which indicate CPU load…do i?This project has constants:It is connected via USB (, and preferably, but optionally, entirely powered via USB / 5V @ 500mA envelope)Data is fed serially via a USB-to-serial moduleThere are some Questions:Thevoltage regulating black boxis a mystery: …what could be inside? …PWM? …booster+switches+resistors?How much power do those panel meters consume?Maybe someone already built a \"serial analog duty cycle meter\" but DuckDuckGo didn't find it?What alternatives do exist? …maybe re-purposing a VU meter (those are basically Amps meters, right?)?"
},
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 19, 2016, 01:26:22 pm",
"content": "I found this ->https://learn.adafruit.com/trinket-powered-analog-meter-clock?view=all<- an analog meter clock. They use µA meters. I think i can go from there."
},
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 19, 2016, 01:41:01 pm",
"content": "Seems like someone else had my idea before:http://www.sharebrained.com/2012/05/30/the-monulator/http://www.lungstruck.com/projects/pc-meter/… here are some more exampleshttps://www.google.de/search?tbm=isch&q=Clock+Analog+Meterhttps://www.google.de/search?tbm=isch&q=analog+usb+meter"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 19, 2016, 02:01:28 pm",
"content": "Arduino with enough PWM pins for the number of meters. RC filter for each meter with a time constant of the order of 0.1 seconds to get smooth movement, then direct to the meter coil. Adjust the total series resistance for full scale defection with a steady 5V output level. Its trivial enough not to even need a PCB apart from the arduino board, which should be bought without headers fitted so you can solder direct to it.The Arduino Nano only has 6 PWM pins so if you have more than 6 cores you need another solution. I suggest Arduino Pro Mini, which doesn't have on-board USB to serial. Feed all the Arduino RX lines in parallel via the same USB <=> serial converter, and use a protocol that 'tags' each value with the core meter its for, e.g. a binary protocol consisting of a continuous byte stream of [0x80 | meter_address<<1 | (PWM_value & 1) ],[PWM_value>>1], Because the high bit is set for the first byte of each meter block, synchronisation is easy. Set the first meter address by grounding a pattern of spare digital inputs on each board so they can all run absolutely identical firmware.That's the cheap and easy way to do it one-off. If you wish to mass produce them there are better options e.g. multi-channel LED driver chips with individual PWM dimming - just fit RC filters feeding meters instead of LEDs."
},
{
"post_id": "",
"author": "JS",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 19, 2016, 03:26:43 pm",
"content": "I don't think you need RC filters, the meters usually are slow enough so you don't have to worry about a fast enough PWM and then your smoothing could be done in software. Which is usually what you want with µC projects, as lower part count as possible, lines of code comes easier to swap if the first try isn't what you wanted.Then, for theyou need to understand a basic of how they work, of course you need a DC one. They move the needle proportionally to the current in the winding, the winding has a resistance, you could add a resistor in series to increase the voltage at the same current or you could use a shunt resistor in parallel to increase the total current for the same current through the winding. First, you want a low current instrument so you don't need to feed more power than what you need, second you want a low voltage instrument so you don't need to have a boost circuit to get to the max range. The easiest choice would be a 5V meter, so you have the 100% with 100% duty cycle, but the needle won't be death on 100%, so probably better to start with a lower one and have a little room to play. As you are adding a resistor you could just go for the lower current meter you can find (without getting crasy low cause they are more expensive) Try to get something low enough it can be driven directly from the µC, 1mA for example. Then you could add a trim for each one and leave space in the board in case you need that cap, you could add one later to dampen the PWM freq if needed. Or just buy the cheapest one, open (while you change the backing paper) and take the unneeded resistor out.JS"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 19, 2016, 03:36:00 pm",
"content": "Arduino PWMs aren't always that fast (can be as low as 488 Hz) and the RC filter also protects the MCU from back-EMF from PWMing the meter coil inductance. You need a resistor anyway to set the FSD and slapping a cap across the coil doesn't significantly increase the cost."
},
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 25, 2016, 12:00:29 am",
"content": "Hey there!Here's an update on the project progress.Firstly, my Arduino firmware.The host script, that collects CPU and RAM load data and pushes it to /dev/ttyUSBn does not exist, yet. I'll publish it in this thread, once it's done.Code:/*Serial Analogue Duty Cycle MeterArduino firmwareAuthor: faekjarzVersion: 20161124.2License: WTF-DNSM (Public Domain -ish)> Do Whatever The Funk you want with it, but> Do Not Sue Me if it burns your house and/or kills your cat!Developed and tested on an Arduino Nano 3 clone w/ CH340G USB ttyThe communication protocol is simple. One line per dataset,terminated by a line feed char (\\n). A dataset comprises of an integerchannel identifier, a colon, and a duty cycle integer of max 3 digits.e.g. 0:42\\n1:69\\n0:100\\1:0Datasets will be somewhat validated, and the duty cycle values will beconstrain()ed to the range of 0 to 100 (%). The duty cycle values willthen be map()ed (translated) to the calibrated full scale PWM values.For full scale PWM calibration, i used the Fade example,from the Arduino IDE: File > Examples > 01.Basics > Fade.I adjusted fadeAmount to 1 and played with the 255 in the if statement.I used an initial maximum of 100, and a 22k resistor between pin and meter,then incremented my way up to full scale, until the needle didn't move further.Channel data is identified by the array index.i.e. chPin, calPWMfs, ... relate to channel 0 (1st),chPin, calPWMfs, ... relate to channel 1 (2nd), ...If your setup has more than two meters, well then, just add more channels. ;DOnly the first 3 variables, chCount, chPin, and calPWMfs, have to be altered.*/// the amount of channels: 2 meters = 2 channels = 2// afaik, there is no method to count array elements, must set manuallyconst int chCount = 2;// to wich pins the meters are connectedconst int chPin[] = {3, 5};// calibrate max PWM for full scale deflection// These are MY values, for MY meters, and MY 22k resistors// Your cal may vary.// 0, right, yellow, 152// 1, left, red, 177const int calPWMfs[] = {152, 177};// miscellanious initialisationconst boolean d = true; // serial debuggingconst int loopDelay = 50; // milliseconds (1/1000)boolean inputReady = false;String inputString;int seppos;int ch;int duty;int valDuty; // an array with chCount elementsint valPWM; // an array with chCount elementsvoid setup (){// initialise UARTSerial.begin(9600);Serial.println(\"begin\");if(d)Serial.println(\"debug output is enabled\");if(d){Serial.print(\"channels: \");Serial.println(chCount);}// set meter pin modefor (int i = 0; i < chCount; i++){pinMode(chPin, OUTPUT);if(d){Serial.print(\"channel \");Serial.print(i);Serial.print(\" pin \");Serial.print(chPin);Serial.println(\" mode: OUTPUT\");}}}void loop (){// handle input when readyif (inputReady){if(d){Serial.println(\"inputReady\");Serial.print(\"inputString: '\");Serial.print(inputString);Serial.println(\"'\");}// find separatorseppos = inputString.indexOf(':');if(d){Serial.print(\"seppos: \");Serial.println(seppos);}// validate separator positionif (seppos < 1){if(d){Serial.println(\"nope: invalid input\");}}else{// extract channel id fieldch = inputString.substring(0, seppos).toInt();if(d){Serial.print(\"ch: \");Serial.println(ch);}// extract duty cycle fieldduty = inputString.substring(seppos + 1).toInt();if(d){Serial.print(\"duty: \");Serial.println(duty);}// constrain duty cyle value (0 - 100%)duty = constrain(duty, 0, 100);if(d){Serial.print(\"constrained duty: \");Serial.println(duty);}// update memory and meters only if changedif (duty == valDuty) {if(d){Serial.println(\"nope: no changes\");}}else{if(d){Serial.print(\"old valDuty: \");Serial.println(valDuty);}valDuty = duty;if(d){Serial.print(\"new valDuty: \");Serial.println(valDuty);}// map value to calibrated PWM valuevalPWM = map(valDuty, 0, 100, 0, calPWMfs);if(d){Serial.print(\"mapped valPWM: \");Serial.println(valPWM);}// update meter pin, set new PWM valueanalogWrite(chPin, valPWM);}}// handling done reset input varsinputString = \"\";inputReady = false;}// everyone loves a little nap, right?delay(loopDelay);}void serialEvent (){while (Serial.available()){// collect new bytechar newb = (char)Serial.read();// check for newline (\\n), end of datasetif (newb == '\\n'){inputReady = true;}else{// append to string variableinputString += newb;}}}Secondly, a picture of the disassembled dual meter, that arrived from China the other day.…and a screen shot of the Serial Monitor with some debug output"
},
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 28, 2016, 03:00:15 pm",
"content": "May I introduce the Pussy Meter.It doesn't purr, but its whiskers twitch.Here's a video of it:with twitter account:https://twitter.com/faekjarz/status/803241651074371584without twitter account:https://video.twimg.com/ext_tw_video/803241308890533888/pu/vid/1280x720/UJz6VopR6-nzyP_A.mp4Here're the essential project files, see attachment:SerialAnalogueMeter.ino: Arduino firmwareSerialAnalogueMeter.sh: Linux host shell scriptscale.svg: the face plate created with Inkscapeoutput.pdf: same face plate, different file format…this is the meter I used:https://www.aliexpress.com/item/new-SZ-70-Panel-Dual-SWR-Forwad-Reflected-VU-Meter-100uA/1585330306.html"
},
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 21, 2017, 12:18:15 pm",
"content": "Pussymeter mk 2:Firmware / script upgradei hope you don't mind my thread cross-linking:https://www.eevblog.com/forum/beginners/iterating-serial-ports-to-identify-the-target-device/The systemd upgrade, i.e. updated project ZIP archive, will be posted here in this thread."
}
] |
2025-10-17T18:58:17.459751
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(dwin-display)-danger-high-voltage-for-esp32-and-others-below-5v/
|
[Dwin Display] Danger: high voltage for ESP32 and others below 5V - Page 1
|
[
{
"post_id": "",
"author": "rtek1000",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "March 09, 2024, 06:31:50 pm",
"content": "Hello,The DMG80480Y070_02NN display is releasing 5V at output TX2.But Datasheet says: Output Voltage (TXD): 3.2 Typ.I have 2 displays and they are the same.My ESP32 started to stop receiving data from the display.You have to be careful with this equipment without very reliable quality control.If the software has a lot of BUGS, be suspicious of everything.https://github.com/dwinhmi/DWIN_DGUS_HMI/issues/17"
},
{
"post_id": "",
"author": "ozcar",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 09, 2024, 08:24:01 pm",
"content": "The page of the datasheet you posted there gives no maximum for the TXD high level (\"1\") output voltage. It also mentions \"5V TTL\" (or jumper optionally, \"RS232\", but I don't know why there is then only one set of input and output voltages given)."
}
] |
2025-10-17T16:39:11.698439
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(electrical-wiring-question)-ac-wires-sizing-for-current-rating-and-distance/
|
[Electrical wiring question] AC wires sizing for current rating and distance. - Page 1
|
[
{
"post_id": "",
"author": "aramosfet",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 25, 2014, 11:59:17 am",
"content": "Hi All,I have a basic question on Electrical wiring. I've been setting up a small electronics lab at my home. Unfortunately, there aren't any electrical outlets at the place. So I set out to do the electrical wiring myself. My requirements were fairly simple. Enough outlets for a desktop PC, Laptop, an oscilloscope, a power supply, Few outlets for soldering station, lighting etc. I calculated that the maximum power drawn shouldn't exceed ~1.2KW (230V 50Hz here).While doing the wiring, i ended up buying a 70m spool of 1Sqmm multicore (~19 strand ??) local brand wiring. I didn't see any safety certifications or labels. I completed the wiring and connected all the outlets. At the end I checked for shorts between line/neutral and ground, everything was fine. Then for some reason I decided to check the resistance. I was surprised to see 2ohms for the roundtrip length of 20M on Line and neutral. The total length of the wiring is ~10M. That would mean, if i'm pulling the estimated 1.2KW through the wires, I'd be dissipating a 54W in the wires alone!!!This seems far too much. Not to mention the fire hazard.I compared the resistivity datasheets for well known branded cables and they specify ~20 ohms/km for 1sqmm multistrand cables. Compared to that, the ones I've got have about 5 times resistance for the same length.The question I have now is, Should I rip out all the wiring and redo with branded cables. Are there any other options? How should I size the wires for the application I have.Also, why do all the sizing suggestions for cables only talk about current capacity alone? Shouldn't the length of the cables also be considered?Thanks,"
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 25, 2014, 12:08:31 pm",
"content": "It might be a mislabelled roll of 0.75mm wire or even a copper coated steel wire ( check with a magnet) or even thinner wire sold falsely. 1.2kW is around 5A, so a 10v drop is within the limits of a mains cable, as you typically can have a max drop of 10% from nominal mains voltage. Yes the cable will get warm, but if you want a cooler cable you have to have more copper, like 1.5 or 2.5mm cable. Preferably you should have a breaker of around 5A to protect the cable, or do it properly and use a 2.5mm cable so as to have the same rating as the wiring in the wall."
},
{
"post_id": "",
"author": "Rerouter",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 25, 2014, 12:12:08 pm",
"content": "I agree 2.5mm cable is really recommended for a dual outlet (on 230V mains) as who knows one day you could want to vacuum the lab and poof, fire starts off in the wall, (2.5mm is rated for 16A according to my countries regulations)also another point is that the earth return (if your country uses one) is recommended here to be under 2 ohm to ensure your circuit breakers will go off fast and reliably,"
},
{
"post_id": "",
"author": "HackedFridgeMagnet",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 25, 2014, 12:24:48 pm",
"content": "Also how good is your multimeter? you can short the leads and subtract the amount shown from your 2 ohm figure.How did you get 54watts? 5A x 2 ohms is 10 watts.oopsAnyway (in order)first you decide what your load is.work out max load current.choose a fuse or circuit breaker to let this amount of current through.then choose a cable that will carry more current than the circuit breaker.the current carrying capacity is dependent on the conditions of the cable run as well as the CSA, and also maximum ambient temperature, local rules and temperature rating of the cable.but 1mm csa is only good for approximately 5amps.You need to check the local rules and conditions.Current carrying capacity is basically trying to measure the amount of current that it can carry before overheating.Voltage drop is another separate limitation on cabling systems.In Australia we cant use less the 2.5mm csa for power outlets."
},
{
"post_id": "",
"author": "aramosfet",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 25, 2014, 12:44:51 pm",
"content": "Quote from: HackedFridgeMagnet on May 25, 2014, 12:24:48 pmI have taken the relative readings from the multimeter, So the probe resistance is not included.P=I^2 * R isn't it?@SeanB , I checked the cable again and it's not copper coated steel cable. Should most likely be 0.75mm. no easy way to check that?I should probably change them to atleast 1.5sqmm cables.Thanks,"
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 25, 2014, 01:05:27 pm",
"content": "Most likely a 0.75 cable with a false rating. You can run 2 cables and have the outlets shared on them, so that you have half the load on one and half on the other if you want, or with lights on one and all on the rest. That way you can switch off all except lights fast."
},
{
"post_id": "",
"author": "HackedFridgeMagnet",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 25, 2014, 01:19:43 pm",
"content": "Yeah lol brain fade."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 25, 2014, 02:26:43 pm",
"content": "Take the cable back out and take it back to the shop and wrap it round his/her neck for selling you such garbage.I agree that you want 1.5-2.5sqmm, if you are doing it do it properly as you WILL run out of capacity sooner rather than later"
}
] |
2025-10-17T20:01:44.493366
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(entry-level)-digital-integrated-circuits-designer-i-need-your-two-cents/
|
(entry level) Digital Integrated Circuits Designer - i need your two cents - Page 1
|
[
{
"post_id": "",
"author": "steamedhams",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 14, 2021, 10:30:29 am",
"content": "I am preparing for an interview for a (entry level) Digital Integrated Circuits Designer.The job ad itself was very extensive and i am familiar with the other areas well. However, I am not confident with my knowledge of the areas below.I'd appreciate if people could give their two cents so I can go on a deep dive on these areas based on your inputs. I am worried of any blinds spots before going into the interview.wafer test parametric specificationsI covered Fault models (stuck at, Observability & Controllability..etc) at Uni, but thats about it...CPU architecturesI am aware of x86 and RISCV, are there any other commonly used ones i should know of??DMA managementWhat could this refer to? IP Core to manage memory or something else??"
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 14, 2021, 02:48:03 pm",
"content": "Quote from: steamedhams on July 14, 2021, 10:30:29 amThe ARM architecture would be important and knowing how to set up the peripherals to use DMA would be helpful.https://deepbluembedded.com/how-to-receive-uart-serial-data-with-stm32-dma-interrupt-polling/BTW, the STM32xxx ARM chips seems to be very common. These chips are probably a good place to start.https://www.st.com/en/microcontrollers-microprocessors/stm32-32-bit-arm-cortex-mcus.htmlMore fun is the PSOC 6 by Cypress.https://www.cypress.com/products/psoc-6-microcontrollers-32-bit-arm-cortex-m4m0"
}
] |
2025-10-17T17:25:45.033276
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(esd)-(in-space)-ground-to-earth-vs-eliminating-local-potential-difference/
|
[ESD] (in space) ground to earth vs. eliminating local potential difference - Page 1
|
[
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "August 25, 2018, 12:08:59 pm",
"content": "Hey there, enginerds!I was thinking about electrostatic discharge / ESD; what it is and how it works. I just watched a YouTube video about servers. Those servers have been decommissioned and unplugged from mains grid. The videographer touched some exposed RAM modules without wearing an ESD protection device, but he touched the metal case 1st, and therefore created equilibrium.That got me thinking. What kills / damages ICs is the discharge, the arking and sparking, caused by a potential difference. But if the handler and the handled device have reached potential equilibrium, by touching the case, there'll be no discharge / ark / spark. So, the now connected system (handler + device) still has an electrostatic charge, a potential difference to earth ground.Wouldn't that be a safe scenario, without actually being grounded to earth?I guess it's safe, until the workspace system (bench + handler + device) suddenly connects to earth ground potential, right?My point is, that grounding to mains earth is not actually necessary, as long as all parts of the whole workspace system \"floats\"(?) at the same potential.Right? Correct me if i'm wrong.A few more thoughts:While i was writing this post, i thought about relevance; is this actually relevant, or am i answering my questions by investing thought in order to ask said same question. Then i thought about manual satellite maintenance, where there's no way one could possibly ground to earth. I guess, it comes down to potential difference.Another question:Are EVA tethers conductive; i mean, there are two entities in non-conductive vacuum, very likely to have a differential in static charge…? …there's probably a physical contact protocol; something similar to what helicopter crews have for high voltage cable maintenance. (EVA: Extra Vehicular Activity, in space flight, satellite maintenance) I'll forward this post to Scott Manley on twitter, maybe he gets a video idea out of it."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2018, 12:47:43 pm",
"content": "Right, the only reason grounding is ever used is because of convenience and simplicity.When you have to educate a billion workers about electricity, it's a lot easier to tell them to grab a pipe (or some more abstract version thereof, like a wrist strap) and use grounded work mats, than to teach and certify each and every one about something they'll probably never fully understand anyway, and also never use again.Dunno about tethers. There can be quite large voltages generated on them (if conductive), due to induction at the great velocities crossing through Earth's magnetic field. Which in turn generates large currents, due to (I suppose) field emission, and what little gas and plasma there is out there (the mean free path in LEO is, what, a bit less than a meter, right?).Tim"
},
{
"post_id": "",
"author": "Rerouter",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2018, 12:56:12 pm",
"content": "In space tethers also get interesting due to charged solar wind particles,EVA tethers generally still use a foil thermal insulation which acts as a ground wire out to the astronaut, not to mention there gloves are made out of very good insulators,Scott manly recently did a video about the gyroscopes failing in satellites, this was in effect a solar wind driven ESD event into a mechanical system, the charge caused enough current to melt parts of the metal on a bearing surface.Similar things happen to IC's, the power dissipated from the current flowing over an isolation gap generally melts both sides a little and leaves growths that extend towards the start and end point of that arc."
}
] |
2025-10-17T18:26:24.600342
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(extreme)-esd-or-emp/
|
[Extreme] ESD or EMP? - Page 1
|
[
{
"post_id": "",
"author": "CZroe",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "March 20, 2019, 12:44:55 pm",
"content": "One month ago we took a direct lightning strike to the house. My brother’s car was parked only a few yards away from the obvious point where the lightning found it’s way to ground but it didn’t have a mark on it so we thought it was fine......It wasn’t.Insurance totaled it.He did have two tires in the grass beside the paved driveway. I doubt that mattered much but, well, my car was parked next to his and it was fine. He didn’t have anywhere to go with his car for a couple days, so we were kinda surprised to discover that it wouldn’t start. Everything lights and bings like it should with the key in there except the indicator for selecting PRND12 doesn’t show and nothing happens when you turn the key. It uses an indicator light behind the transmission selection instead of a physically moving needle. If the system doesn’t know it’s in Park or Neutral then the neutral safety switch will not allow it to start, so I was hoping that’s all it was.Fuses and relays all checked fine. Shop said the computer and starter were bad and that those needed to be replaced before they could even start looking for other issues. It seems that the insurance company has dealt with lightning strikes enough to know that other electrical issues are inevitable and they just decided to total out the car at that point.I don’t know much about vehicle electronics but since I see no evidence of a direct hit, wouldn’t the EMP damage likely be less severe than a typical lightning strike? Think they are just treating it as a lightning strike instead of an EMP? What do you think was more likely wrong with it? Looking for info on EMP and cars mostly leads you to speculative doomsday prepper stuff (nothing useful).More:https://imgur.com/a/w44Mxoz"
}
] |
2025-10-17T18:14:21.955370
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(fluke-17b)-400ma-fuse-blown-fuse-is-replaced-but-there-is-no-continuity/
|
[fluke 17b+] 400ma fuse blown: fuse is replaced but there is no continuity - Page 1
|
[
{
"post_id": "",
"author": "snailevangelist",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 19, 2023, 12:00:39 am",
"content": "ahoy everyone!please bear with me since i am still new to electronics, but i could use some assistance. recently, i did a thing that i now know i definitely shouldn't do— measuring current in parallel with a circuit instead of in series. the fuse on the 400ma port blew, naturally. i ordered some new fuses, which i have tested and are fine, and replaced the old one. interestingly, when i measure continuity between the com port and the 400ma port, there is still no continuity. i've blown the 10a fuse before and replaced it, but i still get continuity between that path and the com port.does anyone have any suggestions, guides, or means of fixing/fault finding this issue? any help or advice would be really appreciated.thank you!!"
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 19, 2023, 12:21:02 am",
"content": "I've attached a schematic excerpt from a 17B, the 17B+ is likely very similar. As you can see, in any position other than mA, you'll have ~1.1k resistance if you measure from the mA/µA terminal to common. In the mA range, this will be about 1.1R, maybe a bit more. This is presuming you dont use an excessively high test current and the voltage is limited to three diode drops. So to test the mA/µA socket, use the resistance range, not continuity. You can also try measuring a small current to verify that the meter works (or doesn't). If it still appears to be broken, you'll need to take it apart and carefully inspect the PCB for damage. Assuming a correct, original fuse was installed, I'd be surprised if anything else was blown up."
},
{
"post_id": "",
"author": "mwb1100",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 19, 2023, 02:25:00 am",
"content": "Quote from: snailevangelist on May 19, 2023, 12:00:39 amMeasure resistance, not continuity. Fromthe 17B+ manual:Quote10 kOhm will not set the continuity buzzer.On the other handQuoteWhich will trigger the buzzer.(edited to link/quote the 17B+ manual instead of the 17B manual)"
},
{
"post_id": "",
"author": "snailevangelist",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 20, 2023, 05:06:36 pm",
"content": "thank you so much for the reply! i will certainly test this out, unfortunately i am out of town for the weekend. when i come back i'll follow your instructions and make another reply."
},
{
"post_id": "",
"author": "snailevangelist",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 22, 2023, 04:43:52 pm",
"content": "i was finally able to test this out yesterday, and my multimeter (affectionally named \"grumbo\" lol) is chugging along like a champ. in the process of tearing it down, i screwed up reassembling the wheel and the lcd screen and it took me a hot minute to get the whole thing going. i'm glad everything seems to be okay. thanks for your help everyone!"
}
] |
2025-10-17T16:54:16.211927
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(help)-esp8266-esp-01-programming-troubles/
|
[HELP] ESP8266 ESP-01 Programming Troubles - Page 1
|
[
{
"post_id": "",
"author": "ashwinbr",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 29, 2017, 06:56:15 pm",
"content": "Hi All,I'm a newbie in electronics and just getting into Arduino/RaspPi type projects.I'm working on a project to add some ESP8266 MCU based IoT devices at my home (switches, dimmers etc).In trying to upload a firmware on to ESP-01, I've repeatedly failed to even get an AT command to work and I'm desperate.I'd be grateful for any help/advice/pointers towards this.So far here's my setup.Power supply: 3.3v breadboard P/S moduleUSB Serial adapter: FTDI based USB to Serial adapter. Connected to a Windows 10 PC using FTDI 2.12.28.0 drivers with a 8/16/17 timestamp.I've tried 3 different adapters all based on FTDI chip, including one that says genuine FTDI chip. :-)ESP-01 connections as follows:Normal Working mode:FVCC --> +3.3vGND -> GroundCH_PD --> +3.3vGPIO 0 --> OpenGPIO 2 --> OpenRX pin --> TX of FTDITX pin --> RX of FTDIFirmware Upload mode:VCC --> +3.3vGND -> GroundCH_PD --> +3.3vGPIO 0 --> GNDGPIO 2 --> OpenRX pin --> RX of FTDITX pin --> TX of FTDISoftware:ArduinoIDE (All the appropriate boards' libraries updated)ESPEasyESPlorerPutty terminal emulatorNormal working mode:When I hook up everything all the right lights are on (power indicator on FTDI, power indicator on ESP-01)Blue light flickers initially as the module is coming up and shuts off.When I connect the terminal emulator (9600 and 115200 baud), I get a constant stream of junk characters.Most of the time it doesn't respond to any AT commands I type and rarely it responds back with garbage characters.Firmware Flashing mode:GPIO-0 conected to groundRX to RX of USB moduleTX to TX of USB Module.Does not respond to any AT commands, terminal is quiet/blank.When I run ESPEasy flash command I get the following error about 9 times:trying to connectflush startsetting serial port timeouts to 1 mssetting serial port timeouts to 1000 msflush completeespcomm_send_command: sending command headerespcomm_send_command: sending command payloadread 0, requested 1warning: espcomm_sync failederror: espcomm_open failedI would be very grateful if you could kindly give me any pointers on what I'm doing wrong and how to get this working.Thank you so much!-Ash.PS: I have other ESP-01 based switches like Sonoff switch and Sonoff S20. I've not had any luck with these either."
},
{
"post_id": "",
"author": "hamster_nz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2017, 08:43:29 pm",
"content": "On a fee modules I played with many months ago I had to add a pull-up on one of the GPIO pins to enable programming. Sorry I can't be more specific - it was a while ago!"
},
{
"post_id": "",
"author": "hamster_nz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2017, 10:26:02 pm",
"content": "Found a link regarding pullups....https://www.forward.com.au/pfod/ESP8266/GPIOpins/ESP8266_01_pin_magic.htmlThere is a table indicating a pull-down on gpio0 and a pull-up on gpio2"
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2017, 11:43:44 pm",
"content": "Not sure what module you are using but for Nodemcu use ESPFLASHERto restore firmware.https://github.com/nodemcu/nodemcu-flasherRegards, Dana."
},
{
"post_id": "",
"author": "ashwinbr",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 30, 2017, 05:04:30 am",
"content": "Hi All,Thanks so much for the input.I will definitely check out the URL for pullup resistors (I've not used it in my setup, so it could be something I possibly need).Also thanks for the new flasher tool. Will check it out.THank you.Ashwin."
},
{
"post_id": "",
"author": "LukeW",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 30, 2017, 09:35:04 am",
"content": "RX pin --> TX of FTDITX pin --> RX of FTDIThis should be the case for both programming mode and normal operating mode - always.Other than that, check that your 3.3V supply can supply sufficient current.Check that your FTDI (or similar) device works by sending characters in a serial terminal, and then just connect the TX back to the RX with a wire, and confirm that you now get an \"echo\" from the serial port.Generally, I would not recommend the ESP-01 as a worthwhile beginner's device.It's hard to set up for beginners, you have to provide the serial comms and 3.3V supply, you can't use it on a breadboard, and you only get a couple of GPIO pins.An ESP-12 is about the same price, or a Wemos D1 board, or a NodeMCU Amica board, are all much easier to use.Something like an Amica is slightly more expensive but gives you the 3.3V and serial already sorted easily for you.GPIO15 is already tied to ground on the ESP-01. There are already internal pull-ups on GPIO0 and GPIO2, but you can try adding some yourself, like 10k or 4k7, and see if there's a difference.Maybe try adding a decoupling capacitor on the 3.3V supply too."
}
] |
2025-10-17T18:47:49.538446
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(help)-finals-steps-with-altium/
|
[Help] Finals Steps with Altium - Page 1
|
[
{
"post_id": "",
"author": "simon66",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 23, 2013, 05:01:47 am",
"content": "Hello all,I've been a eevblog viewer for a few months now and I finally decided to join.I've used eagle CAD for all of my personal projects. A friend of mine bought me Altium Designer 13! I was able to design my project but this is also my first time sending it to a fab (oshpark.com to be specific)How can I create a keep-out Layer? On my project the \"board shape\" is what I want my final board to look like. I've seen some places and they have some fancy lines around which I don't have.Can some one take a look at my project and point me out what I did wrong? Or what I can improve on? Any help is appreciated!Thank you so much!"
},
{
"post_id": "",
"author": "David_AVD",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 05:23:26 am",
"content": "I always draw the board outline on the keep-out layer with the keep-out attribute checked.EDIT: I usually have the traces coming out of the centre of pads, especially round ones."
},
{
"post_id": "",
"author": "simon66",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 23, 2013, 04:31:50 pm",
"content": "Quote from: David_AVD on October 23, 2013, 05:23:26 amThat's my problem I think. How do I draw the board outline. I see info on the wiki but nothing really that helps me out.Thanks!"
},
{
"post_id": "",
"author": "M. András",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 05:08:29 pm",
"content": "like a track. draw a line simply shortcut is p+l, switch the to keep out layer and draw it there, same with silk screen if you want custom shapes and you can define the board shape from the menu too"
},
{
"post_id": "",
"author": "Rufus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 06:40:47 pm",
"content": "Quote from: simon66 on October 23, 2013, 04:31:50 pmYou seem to have already defined the board shape (which is very difficult to manufacture with the square internal corners).You can manually draw lines and arcs around it on a mechanical layer to provide the manufacturer with the outline. The 'Design | Board Shape | Create Primitives from Board Shape' will do it for you automatically."
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 08:56:57 pm",
"content": "DRAW THE BOARD SHAPE ON THE KEEPOUT LAYER.IF THE LAYER IS NOT VISIBLEO-L AND TICK THE 'KEEPOUT LAYER CHECKBOX.THEN DRAW USING ARCS , LINES WHATEVERS-Y SELECT ALL ON LAYER ,D-S-D DESIGN BOARD SHAPE DEFINED OBJECTSOops didnt meant to shout. i'm in altium designer right now so capslock is on ... before i looked at what i wrote..."
},
{
"post_id": "",
"author": "simon66",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 23, 2013, 09:00:29 pm",
"content": "Quote from: M. András on October 23, 2013, 05:08:29 pmQuote from: Rufus on October 23, 2013, 06:40:47 pmThanks! Does it matter how thick the line is? The \"Create Primitives from board shape\" does the trick faster but I keep getting some errors (Due to default Rules). I was able to make it but not sure if the line thickness matters.Thanks again!"
},
{
"post_id": "",
"author": "AlfBaz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 09:30:34 pm",
"content": "Quote from: free_electron on October 23, 2013, 08:56:57 pmI was wondering who was making all that racket. Thought there was a fire!!"
},
{
"post_id": "",
"author": "mrflibble",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 09:37:56 pm",
"content": "Quote from: free_electron on October 23, 2013, 08:56:57 pmIs this some secret Altium handshake for those in the know? Turn capslock on, it will give you better PCBs? O_o"
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 11:03:33 pm",
"content": "Leaving capslock on in altium has an advantage ...netnames and part designators are all neatly in capital letters like they should be."
},
{
"post_id": "",
"author": "mrflibble",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 11:40:34 pm",
"content": "MY NETNAMES ARE IN CAPS TOO, BUT I DONT oh wait, but I dont have capslock on for that. So basically, uppercase netnames. Check!Incidentally, do you use netnames starting with a plus/minus sign for supplies (a la +1V8, -12V), or some symbolic name like VCC/VDD/VWHATEVER?"
},
{
"post_id": "",
"author": "David_AVD",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2013, 11:44:08 pm",
"content": "Quote from: simon66 on October 23, 2013, 09:00:29 pmI use a 10 mil line for the board outline."
},
{
"post_id": "",
"author": "AlfBaz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 24, 2013, 12:32:31 am",
"content": "Quote from: mrflibble on October 23, 2013, 11:40:34 pmWhile we're at it what about net names with an Overbar or to put it another way, active low net names. Sure it looks pretty in the schematic** but locating these in the PCB netlist is not much fun when you have to type /l/i/k/e t/h/i/sSo do you suffer the mangled netname or go for something like the preceding underscore system**When placing net lables on multiple pins the font size and pin grid conspire to hide the overbar with the above wire"
},
{
"post_id": "",
"author": "Rufus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 24, 2013, 12:58:44 am",
"content": "Quote from: AlfBaz on October 24, 2013, 12:32:31 amI have settled on a lower case 'n' prefix. If the nets come from a processor or programmable logic I want to use the same names in the firmware or HDL.Supply rails I generally name like V5V or V3V3 or VM5V (for -5) but not strictly. It depends what makes most sense for particular circuits."
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 24, 2013, 01:15:49 am",
"content": "P12V N12V V3V3 V5V L3v3 A3v3Positive 12 voltNegative 12 voltVoltage 3v3Voltage 5VLogic 3v3Analog 3v3thats how i work.please dont use overbars on netnames ! the problem is on dense schematics the overbar tends to disappear under a wire of the pin above ! and thi cause problemsnuse lowercase n before or after netname to indicate active lownRESETRESETnI leave capslock on when in altium as netnames , part designators part values are always uppercase120R 1K2 12K 120K 12R 0R331U 10U 10N 2U2 (CAPACITORS)1UH 2U2H 10UH (INDUCTORS)AD720 LM317 .Nobody writes lm317 or ad720also : NEVER EVER use dots orcommas in part values. use the Multiplier letter instead of the dot. : 12.7K = 12K7dots tend to disappear if you copy a printout... and your 12.7k becomes 10 times larger ..."
},
{
"post_id": "",
"author": "ludzinc",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 24, 2013, 01:49:35 am",
"content": "Quote from: free_electron on October 24, 2013, 01:15:49 amIMHO, k should be lowercase, as it's defined in SI units.... i.e. 1k2 not 1K2."
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 24, 2013, 01:52:18 am",
"content": "I actually prefer lowercase k simply because it's less likely to be mistaken for a capital R in a shitty scan/copy (and if you think scans can't bethatshitty.... trust me, they can). SI is irrelevant, they also define both m and M but you're a dumbass if you use both of those in a schematic. And they sure as hell don't define the \"1k2\" notation."
}
] |
2025-10-17T20:14:31.416894
| 17
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(help)-parts-or-circuit-to-control-5v-rail-with-min-loss/
|
[HELP] parts or circuit to control 5v rail with min loss - Page 1
|
[
{
"post_id": "",
"author": "allenpan",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "March 21, 2016, 12:55:03 pm",
"content": "parts or circuit to control 5v rail with min losslong story short: I have MCU that use 2.1v for GPIO, and i have a separate 5v circuit, i would like to use the 2.1v logic to switch 5v on an off... (5v will be up to 200mA, typical 100mA)feel free to suggest other parts or circuit..but simple with min part countsi did exploredBJT (2N3904): problem, the Vce has 0.6v drop at 200mAEnhanced n-MOSFET: problem, Vgs threshold = 1.8v-2.1v too close to my logic voltage, and Vds = 0.6 drop as well...any other suggestion? i was thinking get another controllable voltage regulator, but i dont know if that is good idea or put too much load on the 3.3v rail..-Allen"
},
{
"post_id": "",
"author": "ovnr",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 21, 2016, 01:17:32 pm",
"content": "Use a dedicated PDU IC, like theTPS22929D?Alternatively, just use a BJT to control your FET. Or a cheap gate driver."
},
{
"post_id": "",
"author": "soligen",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "March 23, 2016, 03:31:22 pm",
"content": "The AO3400 has a Vgsth under 1.5V."
}
] |
2025-10-17T19:21:51.565834
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(help)-suggest-opamp-to-shift-and-gain-50x-of-ac-signal-to-adc/
|
[Help] Suggest opamp to shift and gain 50x of AC signal to ADC? - Page 1
|
[
{
"post_id": "",
"author": "nhn",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 22, 2019, 02:20:26 pm",
"content": "HiI'm new here. Sorry if my English is not good.I has a simple knowledge about Electric. I try to design my own energy meter using voltage transfomer, current transformer and STM32's ADC. To read AC Voltage I use current type transformer, output swing from -0.033V to 0.033V. I searched and found that I can use differential amplifier with Voltage Ref is 1.65V, below is my schematic. I run simulator and it's working. But I don't know which opamp is good for my case, so I post here looking for any suggestions, dual opamp is better, one for buffer, one for shift and gain. Source voltage is AC 230, 50Hz. SDADC run as 6 MHz, 300ksps.Thank very much"
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 22, 2019, 02:42:20 pm",
"content": "Figure 4-7 in \"Op Amps For Everyone\" - look at curve for TLV2472https://web.mit.edu/6.101/www/reference/op_amps_everyone.pdfThe TLV2472 is a single supply rail-to-rail op amp with output characteristics that get very close to the rails. The TLV2472 is a dual op amp. It is also available as a single and quad. You should still design the circuit to stay away from the rails. Check the datasheet.Rail-to-rail is a marketing term, not an engineering reality. If you look at the output voltage (high and low), you will see that it only comes within 150 mV.http://www.ti.com/lit/ds/symlink/tlv2472.pdf"
}
] |
2025-10-17T18:03:16.062777
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(help)-with-usb-powered-digisparkarduino-with-shutoff-after-3-minutes/
|
(help) Dash camera UPS - Page 1
|
[
{
"post_id": "",
"author": "robotic",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 05, 2017, 01:35:13 am",
"content": "Hi everyone,I bought a dash cam a while back and am not complete sure what is wrong with it. I'm thinking the internal battery is out of most of it's power or something. It works when I turn on the car and the time and date are always right when I start up the car. However, it use to turn off after a couple of seconds and properly power down so my last file would not be corrupt. Now after I shut off the car it pretty much just shuts down immediately and the last file is always corrupt.To solve this, I was thinking of creating a dashcam ups connected to my car 5v -> dashcam ups -> dash cameraSo the dashcam ups bypass will just feed 5v to the dash camera and when the dashcam ups notices that it is not being powered it will count 2 minutes and then turn off. This will let the dash camera finish it's 3 minute write cycle and the last file will be saved.Now I'm not too sure how to make this... I know I will need- some kind of timer (I thought it would just be easier if I use a digispark or arduino)- A way to sense voltage coming from car usb port to tell when there is no more power- A way to switch to battery mode if power is cut off from the car- A 3.7v battery as a power source for the 2 minutes.- A charging circuit for the 3.7v battery. I'm hoping for it to charge the dashcam ups's battery as well as passthrough the 5v to the dash camera at the same time.Any help would be appreciated. This dash camera has sadly(because I had accidents)/luckily saved me from he said she said arguments from a couple of accidents.Thanks"
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 05, 2017, 01:52:04 pm",
"content": "Been looking down this road for a while myself.https://www.eevblog.com/forum/beginners/battery-float-with-current-limiter/msg1331637/#msg1331637The short answer is. It's not going to be easy. Most of the easy options have \"gotchas\".If you are willing to spend money there are a few commercial options, but they cost between £180 and £300.As to the last file being corrupted, it \"could\" be the super capacitor within it has dried out or failed in the heat of the sun stuck in the window constantly. The powering down within a few seconds is perfectly normal, but the corrupt file is not.Note that you do get the odd corrupt file due to the dash cams not properly implementing the error detection and sector marking which should be used for SSD cards.My use case is a little bit different than yours. it seems you only want to power the dash cam for a couple of minutes after the car goes off.For that you could purchaer single super capacitor and wire it across the two power pins of the dashcam. Job done. When the power is on the cap will charge up and supply a smooth 5V (do check it's not 12V which would make more sense in a car). When the power shuts off the capacitor will discharge slowly. A LARGE super cap the size of a D Cell battery will probably run the dashcam for 10+ minutes."
},
{
"post_id": "",
"author": "IanMacdonald",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 05, 2017, 02:42:55 pm",
"content": "Problem I see here is that even if you extend the shutdown time it will still corrupt the last file when it shuts down. Since that could mean half an hour of recording lost it's not very acceptable.I feel that having a dashcam on a separate switch is a better idea anyway. There is the the risk of leaving it on overnight but usually that won't case a flat battery. The draw is about 300mA which means a few Ah overnight at most. The problem with having it on the ignition is that you have to leave the keys in the car to have it stay running at the scene of an incident. That risks having the car stolen.That risk would certainly arise if you rendered assistance to a crashed vehicle and it turned out that the driver was a criminal."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 05, 2017, 02:59:24 pm",
"content": "The is \"Power magic\" boxes, for 12V dash cams, which run direct off a non-switched fuse in the car fuse box, 24/7 using the car battery. They have configurable low voltage cut outs so you should be able to restart the car in the morning.I personally don't trust these. My car is notorious for having a weak battery and high leak current at times. I have left it for a week idle and even after that I could hear the starter motor turn slower. Don't want to put more fuel on that fire.http://www.halfords.com/technology/dash-cams/dash-cam-accessories/blackvue-power-magic-proAlso of note. Dashcams usually save videos in 3-5min chunks for the exact purpose of preventing loss of larger segments. The internal capacitor is meant to last long enough for the dashcam to close the current open file and flush the disk buffer.Note, you read that right, £40 for a low voltage cut off and 555 timer."
},
{
"post_id": "",
"author": "Gregg",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 05, 2017, 09:52:55 pm",
"content": "I've been thinking about the same situation, but mostly I'm concerned that someone will smash a window to steal the dash cam so I remove it most of the time. Anyway I think that a small 12V glassmat lead acid battery powered via a Schottky diode to charge from an ignition on circuit and a battery protection circuit between the small battery and the 5V dash cam power supply to keep from overly discharging the small lead acid battery would be about as simple, cheap and reliable as anything. Here is a link to an ebay seller of a ready made battery protector module:https://www.ebay.com/itm/Under-Over-Voltage-Protection-Module-Battery-Automatic-Charger-Discharger-Board/232477980321You may have to scroll down to review all of the modules offered by this seller."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 05, 2017, 10:13:08 pm",
"content": "One thing to consider is the initial charge current when the small lead acid is part depleted. The car will happily give it 10A if it wants it and (in my case) blow the utility socket fuse.Small SLAs have different float charge voltages too. A car battery will happily sit at 14.40V-15V all day, a small SLA will not.As the OP only needs to run the camera for enough time to end the current video file and start a new one (which will become corrupted), all he needs is a beefy capacitor across the 5V leads."
},
{
"post_id": "",
"author": "robotic",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 05, 2017, 11:53:06 pm",
"content": "Quote from: paulca on December 05, 2017, 10:13:08 pmYes all I need to the current video to end. The dashcam records in 3 minute chunks so technically I only need 2m59s. What is considered a beefy cap? I bought a couple of small supercaps a whileback maybe I'll test it out if that's all I need and time it for dissipation. What would be approx. F? I'm not sure the draw I'm guessing 200mah. I'm assuming 20F @ 5VPower is drawn from an usb adapter connected to the cigarette lighter. So not hard wired into the 12V system"
},
{
"post_id": "",
"author": "suicidaleggroll",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 05, 2017, 11:56:39 pm",
"content": "Quote from: robotic on December 05, 2017, 11:53:06 pmThe camera expects a 5V input, let's assume it can operate down to 4.5V before having issues. It likely draws a watt or more as well. So this capacitor would need to supply at least 1W for at least 3 minutes while only allowing the voltage to drop from 5 to 4.5V. That would require nearly 100F. You're well into series-connected and balanced/protected supercap territory there. There's also the issue of it discharging back into the switched off DC/DC converter, possibly damaging it or discharging the cap prematurely. You could use a diode to keep the current from reversing, but then you lose your 0.5V discharge room. There's also the issue of the minutes-long current surge when powering this on, which would certainly send the DC/DC converter into overcurrent shutdown. Far simpler to use a battery IMO.Of course the simplest option is to just open up the camera and replace the internal battery."
},
{
"post_id": "",
"author": "robotic",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 06, 2017, 12:06:24 am",
"content": "Quote from: suicidaleggroll on December 05, 2017, 11:56:39 pmYeah I thought about that as well. Last time I opened it up, I broke it somehow... Not sure if it was already broken and I just couldn't fix it by adding a new battery or what. Probably the latter. Sounds like too much of a problem to do supercap. I forgot about voltage drain. Doing the ups may also help with future projects or as an emergency solution. I would like to pursue it I think."
},
{
"post_id": "",
"author": "robotic",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 06, 2017, 12:12:46 am",
"content": "Yeah it is probably the battery like I said in my previous post. It surprisingly still keeps time though after a few days, so I know the battery isn't completely dead anyways.I still want to work on it, just as a nice project as well as if I do ever need something like this because it does seem useful to have a ups type device to turn off things after a certain amount of time.I found an article using FQP30N06L for a ups. That might work for 1 part in which it triggers the dashcam off.powerA = carpowerB = upsSo if powerA is providing power turn on FQP30N06L [dashcam will turn on]if powerA is not providing power, start timer for 3 minutes, turn off FQP30N06L.I'm not sure how to bypass powerA and use powerB when powerA is interrupted (car engine off)."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 06, 2017, 08:12:03 am",
"content": "It's likely the cam is powered by a super cap inside it. Which (should) provide enough power to give it a few seconds to close the file it's currently saving when it detects a loss of input power. This is how mine (BlackVue) works.If you have dislodged that cap or broken it some other way then the camera will power down instantly when you disconnect the power and corrupt the last file and potentially the SD card filesystem.Currently when you disconnect the power does the dash cam indicator lights remain on for a few seconds and then fade out or does it just switch off instantly?Mine even has enough time/power to audibly say \"BlackVue shutting down\"There are many cheap and nasty dash cams. How sure are you that the one you have did save it's last file without corruption previously?"
},
{
"post_id": "",
"author": "robotic",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 06, 2017, 01:12:36 pm",
"content": "Quote from: paulca on December 06, 2017, 08:12:03 amMine doesn't shutdown immediately it waits about 2 seconds but requires about 5-8 seconds to properly shutdown (triggering the shutdown when not connected to power. I'm pretty sure it's a lipo battery inside and I know the battery isn't completely disconnected or I would not have any time/date.Anyways, I'm more interested in building the UPS. I may change the battery in the future and have talked about this in earlier posts. Thanks anyways."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 06, 2017, 01:50:12 pm",
"content": "I wonder if you could hack a USB power bank for this purpose. The one I have will not output AND charge at the same time though maybe they exist were they will.This might give you ideas:http://www.theoutpost.org/6-techy/raspberry-pi-usb-power-bank-ups-pass-through/"
},
{
"post_id": "",
"author": "robotic",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 09, 2017, 02:59:53 am",
"content": "Quote from: paulca on December 06, 2017, 01:50:12 pmI bought a couple of powerbank modules and that was actually one of my ideas. Once I get the logic transistor chip I will probably test it out."
}
] |
2025-10-17T18:42:57.045261
| 14
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(help-needed)-oscilloscopearduino-issue-overshooting-and-ringing/
|
[Help Needed] Oscilloscope/Arduino Issue: Overshooting and Ringing - Page 1
|
[
{
"post_id": "",
"author": "Ratents0",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 16, 2023, 04:43:37 am",
"content": "Hello everyone,I'm a newbie to the world of electronics and oscilloscopes, and I am currently facing a peculiar issue with my new Siglent SDS1202X-E oscilloscope and an Elegoo Uno R3 board. I'm generating a square wave with the Arduino, but I'm seeing a significant amount of overshooting/undershooting and ringing. This happens regardless of the frequency of the square wave, and the deviation is quite noticeable (~3V off a 5V signal on both the rising and falling edge).I've tried various troubleshooting steps including updating the oscilloscope's firmware, compensating the probes, calibrating the scope, and more. I've even tried using a different board (Elegoo Mega 2560 R3) to no avail. I'm at a loss as to what's causing this issue.Here's the code I used to generate the square wave:Code:#define REFRESH_RATE 60void setup() {pinMode(12, OUTPUT);}void loop() {unsigned long period = 1000000 / REFRESH_RATE; // total period for one cycleunsigned long halfPeriod = period / 2; // half periodunsigned long start = micros();digitalWrite(12, HIGH);while (micros() - start < halfPeriod); // delay for half period while HIGHdigitalWrite(12, LOW);while (micros() - start < period); // delay for remaining half period while LOW}I've also posted this question on Stack Exchange and provided a more detailed explanation of the problem there, along with some images of the waveform, and my oscilloscope probe connection to the Arduino. Here's the link to the post:https://electronics.stackexchange.com/questions/670233/why-does-my-square-wave-signal-from-an-elegoo-uno-r3-have-3v-overshoot-undershoo.I would greatly appreciate any insights or suggestions that you might have to help resolve this issue. Is this a common issue when generating square waves with Arduino boards, or could there be a specific issue with my setup?Thank you in advance for your help!"
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 04:53:58 am",
"content": "Quote from: Ratents0 on June 16, 2023, 04:43:37 amit depends on the load impedance connected to output port. If there is overshoot and ringing it means that there is impedance mismatch. For example unloaded port.It doesn't depend on arduino. It depends on what you're connected to the digital port."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 04:57:45 am",
"content": "Need to see a picture of how you used the ground spring. The problem sure looks like the ground connection is too long. The photo shown with the ground clip would definitely cause overshoot.What is the 10x probe bandwidth?"
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 05:56:34 pm",
"content": "The oscilloscope pictures you posted on stackexchange look perfectly normal.When you are measuring with the crocodile GND clip, you can't expect a measured bandwith of more then 20MHz and extending your GND lead with the grey \"dupont\" cable makes it even worse. You've got yourself a nice 200MHz scope.Also, if you move the GND wire or hold it in a fist (without disconnecting the wire) you will see the amplitude of the ringing changing. That is a clear indication that this ringing is caused by the GND wire.Now repeat that measurement, but instead of the long GND lead, use small GND clip. The ringing will be (nearly) gone.The crocodile GND lead is much more convenient to use, and I usually combine it with using a 20MHz bandwidth limit on my oscilloscope."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 06:12:57 pm",
"content": "EasyThe ringing is caused by the inductance of that long ground lead (~1nH/mm) resonating with the probe tip capacitance.FFI about theory, practice, and how to improve the issue, seehttps://entertaininghacks.wordpress.com/2015/04/23/scope-probe-accessory-improves-signal-fidelity/As aseparateissue, such resonances occur elsewhere, e.g. flying leads and circuit input capactiances. That's why long leads on solderless breadboards are a bad idea. For alternative construction techniques, seehttps://entertaininghacks.wordpress.com/2020/07/22/prototyping-circuits-easy-cheap-fast-reliable-techniques/.BTW, it is good that you tested, observed, and thought. Not everybody does thatBTW it is also good that you noticed the phenomenon iscompletely unrelatedto your waveform'sfrequency/period. That's because the issue is solely related to your waveform'stransition time. You are now innoculated against the incorrect statements about your \"scope needing 5 samples per clock period\" and related nonsense. FFI about why, seehttps://entertaininghacks.wordpress.com/2018/05/08/digital-signal-integrity-and-bandwidth-signals-risetime-is-important-period-is-irrelevant/"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 06:41:24 pm",
"content": "You should read Jim Williams' comments about probing techniques in app note 47.https://www.analog.com/media/en/technical-documentation/application-notes/an47fa.pdfJim was one of the true greats in analog design and his application notes are fantastic."
},
{
"post_id": "",
"author": "Infraviolet",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 06:52:23 pm",
"content": "If this rippling is problematic in some application, or you fear that the highest point on the ripple could be a large enough voltage to threaten to shorten the life of anything sensitive wired on to it... have a look at some simple low-pass filter circuits to somewhat slow the rise time of that edge."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 09:15:04 pm",
"content": "Quote from: Infraviolet on June 16, 2023, 06:52:23 pmMany digital logic outputs have configurable \"strength\" parameters which limit the output current. The first benefit is to reduce ground bounce (i.e. the voltage induced across the ICs internal lead inductance). The second benefit is to increase the transition time, thus reducing EMI.Beyond that, the best technique is to use appropriate interconnection practices, as described in many textbooks and application notes."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 10:56:08 pm",
"content": "Quote from: tggzzz on June 16, 2023, 09:15:04 pmI don't think the atmega used in the Arduino does though. In this case I suspect the ringing is largely due to probing technique though and is not actually there otherwise. That said, arduinos are often rather carlessly connected to peripheral devices to the point that sometimes it's remarkable that the circuits ever work at all and yet they usually do."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 16, 2023, 11:22:29 pm",
"content": "Quote from: james_s on June 16, 2023, 10:56:08 pmQuite likely, definitely, and rather than \"ever work at all\", I'd encourage the OP to think of such circuits as \"working well enough that you can persuade yourself the intermittent failures aren't really happening\".The OP isn't falling into the lazy way of not-thinking, though, which is an excellent start"
},
{
"post_id": "",
"author": "LukeW",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 18, 2023, 03:49:25 am",
"content": "You really want a reliable, consistent connection between the thing that you're trying to measure, and the scope. Ideally, hands-free and with as low stray inductance as possible, and without mechanical intermittency.I would use a female SMA connector with two very short (<10mm) pigtails of wire soldered onto it, and soldered onto the DUT. (Just tacked in place is fine, as long as it's a reliable solder joint.) Solder it onto the pads on the bottom of your Arduino board, in this case.Then I would use a SMA male-to-male cable and a SMA-to-BNC adapter to connect it to the scope.You now have a completely consistent, reliable connection to the scope, you don't need to hold it, with low stray inductance, with no mechanical intermittency.Much easier way of working IMHO, even if it seems like more work at first.Those \"breadboard jumper\" wires with the round pins and the moulded black rubber part are the worst. I suggest throwing them away. They're even more crap than usual \"DuPont\" jumper wires.(Relatively high resistance, very thin core, low quality soldering, relatively high inductance, intermittent connections.)"
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 18, 2023, 04:45:11 am",
"content": "Your ground connection is way too long for the rise time being measured. Try to reduce it to about 1 cm. Your Siglent probes would have come with little spring grounds. Use one of those."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 18, 2023, 12:51:42 pm",
"content": "One method I like is to use a probe tip to BNC adapter to attach a short RG-174 pigtail which can be soldered into place. This is more useful with switching power supplies where the coaxial pigtail reduces interference from magnetic flux. The disadvantage is added capacitance but length is seldom a problem below 100 MHz."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 19, 2023, 06:38:55 pm",
"content": "Jim Williams discusses all these techniques in the app note I referenced.For poking around an arduino circuit it's probably sufficient to just use the shortest possible ground on the probe tip, but various other techniques have their place."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 19, 2023, 10:51:09 pm",
"content": "Quote from: james_s on June 19, 2023, 06:38:55 pmFor too many decades I've liked HP10020 probes: 1.5GHz with a tip capacitance of <0.7pF, interchangeable 1:1, 5:1, 10:1, 20:1, 100:1 resistive divider tips.They are difficult to find,but you can make your own(unlike mis-named passive \"high impedance\" probes)."
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 19, 2023, 11:04:29 pm",
"content": "I'm sure all these comments are well meant, and have their place, but for probing around in \"arduino circuits\" or on breadboards, just use the covenience of the crocodile clamp ground lead and use the 20MHz internal filter of the scope. That's plenty plus good for most measurements, but of course it does not hurt to get to know more \"advanced\" probing techniques and learn about when they are useful to apply."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2023, 01:00:35 am",
"content": "Quote from: Doctorandus_P on June 19, 2023, 11:04:29 pmThe danger with such a low bandwidth is that it can conceal double clocking in most modern logic."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2023, 07:37:24 am",
"content": "Quote from: Doctorandus_P on June 19, 2023, 11:04:29 pmThat's the equivalent of looking at the world through rose-tinted spectacles or Zaphod Beeblebrox's sunglasses .If you filter out problematic behaviour, then of course you won't see problems. Digital hardware inputs interpret the analogue waveforms to infer digital signals, and the nanoseconds can matter - e.g. dynamic hazard glitches, or hold times, or ground bounce, or random interference. Having said that, orange sunglasses do allow you to see more of a cloud's structure, and hence help find thermals and avoid being forced to find a suitable field"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 22, 2023, 08:56:51 pm",
"content": "But you already know there's going to be problematic behavior, in most cases that isn't what's actually causing the problem though. When I've worked on projects like this what I'm usually interested in seeing is whether my code is doing what I expect it to be doing with the IO, I'll concern myself with signal integrity after I've confirmed that the code is behaving as expected and the thing is still not working. I've found that most devices are remarkably robust and can work properly with all sorts of noise and garbage. It's just toy hobby projects, not avionics or life support hardware."
}
] |
2025-10-17T16:52:47.083933
| 19
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(how-to)-arduino-digitally-controlled-step-down-buck-dc-converter/
|
[HOW TO] Arduino digitally controlled step down buck dc converter - Page 1
|
[
{
"post_id": "",
"author": "MOROZAW",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 17, 2014, 01:37:37 pm",
"content": "Welcome!This is my first post on this forum!My name is Dominik and I am from Poland!I can't find similar topic on this forum and in a web so please help me with my problem.Almost all topics in web not satisfy me and I am still looking for solution my problem.I am looking for the best way to control synchronous dc-dc converter output voltage via uController.My problem is how to control output voltage from converter.I would like to control 4 dc converters from one Arduino.My input voltage is 12,4V and output voltage should be from 5V to 90-100% of Vin.My output current is up to 3A.I have found this application note:http://www.maximintegrated.com/app-notes/index.mvp/id/818but I am not sure if it is the best way.Firstly I was thinking about last option with filtered PWM, but I wouldn't like to make feedback to uC.My second idea was to replace the potentiometer by digital potentiometer, but it's little complicated and I think little overkill.I would like to only set voltage via PWM or voltage or other signal and \"send\" this information (voltage which I wanna have on output) to converter without feedback to uController. DC converter should work alone without \"help\" and modify them PWM signal to maintain the output voltage which I wan't.Is this possible?I hope You know what I meanYesterday I found this two completely different schematics and way to modify feedback loop in dc converters.Please check the attachments. I think this is it what I am looking for. What do You think about my problem?If this topic should be inserted into other, please merge this to appropriate topic.Best regards,Dominik"
},
{
"post_id": "",
"author": "Prime73",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 17, 2014, 01:59:14 pm",
"content": "Watch Dave's videos on his DC power supply where he covers voltage/current control using arduino. Seems like exactly what you need."
},
{
"post_id": "",
"author": "Spike101",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "March 17, 2014, 06:54:41 pm",
"content": "I am currently trying to do the same thing.What i found is this:http://www.microchip.com/forums/m688260.aspxSeems to be similar to what you found, but maybe a bit simpler to implement?Quote from: Prime73 on March 17, 2014, 01:59:14 pmI didn't know Dave covered that in a video. Do you have the video nr.?"
},
{
"post_id": "",
"author": "MOROZAW",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 19, 2014, 12:09:00 am",
"content": "Thanks Prime for reply!I will watch videos within few daysUnfortunately I can't find any EE which can help me with design good feedback schematics, I have friend who can make whole PCB and finished product but he is not sure for this feedback loop so we need little kind of help.Spike, Your link didn't work. I think Dave had in mind Power Supply Tutorial (from about #220 video).I think schematics found by me would be the best, but I'm not sure which will be better.Could anybody tell something more about this circuits?Maybe somebody made something similar?Greetings!"
},
{
"post_id": "",
"author": "MOROZAW",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 30, 2014, 02:22:41 pm",
"content": "Hello everyone!I watched Dave's videos, but still I need some informations and help from You.I need only to adjust output voltage using other voltage reference which is generated from uC after 2-nd stage RC filter and buffer.After small thoughts I decided to use LDO instead SMPS for first project.I would like to understand and learn firstly how to control output voltage before building SMPS.I choose STM LD29150 LDO regulator. As I can see the most of the regulators use the same adjustment so this LDO is for example.Could somebody help with this?I would like to adjust V out from 5V to ~12V.My Vin is ~12,2V, I have Vref from converting PWM to linear 0V to 5V.//editQuoteI have very high problem with finding somebody to help.Any help would be appreciated.Best regards,Dominik"
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 30, 2014, 02:46:44 pm",
"content": "LD29150 can only handle up to 1.5A and that's when properly heatsinked.If you want 3A, consider using something like LT1084 (5A) or LT1085 (3A) which only have 1v dropout (so it allows you to adjust up to 11v if your input is 12v).You could replace the resistor with a digital potentiometer or you could use pwm with a filter to get a voltage and feed that into the adjust pin .. see for example this for help:http://dev.emcelettronica.com/how-to-use-pwm-to-generate-analog-or-analogue-voltage-digital-circuits-part-2Get some parts and practice and try stuff, don't just ask someone to do your work."
},
{
"post_id": "",
"author": "MOROZAW",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 30, 2014, 02:58:12 pm",
"content": "Thanks mariush for reply!I know how to filter PWM but I don't have any idea to interfere in ADJ pin.1,5A is sufficient for my first apllication and project.If it will work I would like to build another one with more Max Output Current.I wouldn't like to use digital pot, as it was wrote at first post, apparently schematics with op-amp is this what I need, but I don't have idea how to change and use it in my application."
}
] |
2025-10-17T20:05:11.484195
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(how-to)-determine-the-accuracy-of-a-circuit/
|
[HOW TO:] Determine the accuracy of a circuit - Page 1
|
[
{
"post_id": "",
"author": "ivan747",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 13, 2011, 03:36:18 pm",
"content": "Hello,I have said it before and I will say it again: I'm not an analog guy, but now I'm trying to get into op-amps so here we go.I have a circuit and I want to determine it's accuracy. It is a current limiter, and I will do a simplified schematic. What I want to do is show you how to get the total accuracy based on the worst case scenario analysis. I'm learning about this too, so if I got something wrong, feel free to point it out.At a glance:The uses a negative feedback loop, so the only critical thing there is a single feedback resistor used for current sensing. I have a voltage reference, with two low tolerance resistors for dividing the voltage and the op amp, of course. I don't know if I should get in the expense of getting a chopper amplifier, which has almost no input offset voltage.Every title in bold is a calculation. Also it might have a small explanation of what it is. As you are doing the worst case scenario, you have to calculate both the lowest possible value and the highest one, and from there calculate the lowest and highest value of the next block, taking in count the values you go on the first block. Then get the worst out of the results and calculate the next one the same way.Error in the input offset voltage:Input offset voltage is an error any real op amp has. When they are used in a feedback loop, op amps will adjust their output until the two inputs have what they believe is the same voltage. But there is an error.If the offset is 10mV (a lot), one of the pins could be 10mV higher than the other. You can confirm this by tying the output to the inverting input and the non-inverting input to a voltage in the middle of your supply voltage. If you have a dual supply, that is GND; if you have a single supply, get two resistors of the same value and connect the non-inverting input in the middle, and both of the ends to Vcc and Gnd.I did a quick approximation and having a 1mV offset with a 1V reference gives me 0.1% of accuracy in the output of the circuit.Code:Offset = 1mVVref = 1V <----This has 2% of accuracy in the reference itself and also we have to take in count the resistor tolerance, but this is just a quick approximation to get the idea of how much offset contributes to the lack of accuracy.Percent of error=?Error/100=Offset/VoltageError/100=0.001/1Error=0.001*100Error=0.1Error is exactly one thousandth of the voltage reference, just like a millivolt is one thousandth of a volt. If the reference was 2.5, then the offset would be even less significant. I am using a volt because I'm working on a 5 volt system and if I increase the input voltage I would have to change the feedback loop in a way that is not convenient for my circuit or I would have to add some gain to compensate the change. That means even more calculations and possibly a trim pot (I won't be adjusting 5 pots per board in a 100 board batch and I won't pay anyone to do it).Now I just have to figure out the rest. I will consult a book I have on the subject.Working on it, please don't give me the answers, I want to figure it out myselfIvan"
},
{
"post_id": "",
"author": "Aners",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "June 01, 2020, 02:17:26 pm",
"content": "Did you figure it out yet?"
}
] |
2025-10-17T17:48:50.945038
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(i2c)(uart)-txs0108e-issues/
|
[I2C][UART] TXS0108e issues - Page 1
|
[
{
"post_id": "",
"author": "mr_byte31",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 03, 2024, 09:10:22 pm",
"content": "Hi All,I am trying to use TXS0108e module (in figure below) to interface my RPI 4 with 5v components (I2C ADC andGPS)I connect the MPU6050 on the 3.3v SDA and SCL and connect the I2C ADC (+5v) to TXS0108e and then to the SDA and SCL (+3.3v). I attached a figure for that.when I trigger \"i2cdetec -y 1\" command , I could see it give different values each time I execute it. I only have two I2C devices no more ( 3.3v and 5v modules).The UART component doesn't work as well. I tested it with another Arduino and it works fine but it doesn't seem to work with TXS0108e.The 3.3v and 5 volts are coming from voltage regulators (ams1117-3.3 and ams1117-5)I appreciate your support."
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 03, 2024, 10:42:04 pm",
"content": "TXS0108E has very low logic low threshold, only 0.15V (meaning if your logic low output from RPi is say 0.2V, it is not guaranteed to be detected as logic low), and its own port A low level output can be as high as 0.55V. Furthermore, when the TXS0108E misdetects the direction (when the logic level is low), it –– and all other similar bidirectional translators –– tends to have a \"step\" in its low level output, which can be interpreted as a logic high by some microcontrollers. I'm not sure if that affects RPi 4 or not, though.This means that for UART and SPI –– which are inherentlyunidirectional, each signal being in a specific direction and that direction does not change at run time –– you are much better off with unidirectional translators like TXU0102, TXU0204, TXU0304, or single signal translators like 74LVC1T45 (in SOT23-6). I've used all of these at quite high baud rates for 1.8V to 3.3V and 3.3V to 5V, and they're worked extremely well for me.I've seen many others have issues using bidirectional translators with UART and SPI, but they tend to be specific to particular components –– i.e., you need to have components that happen to have input/output logic level thresholds closer to the edge than the average –– so it can be very difficult to reproduce using different components from the exact same series.Thus, while TXS0108E is pretty much perfect for I²C, I wouldNOTuse it for UART or SPI. I would use TXU0102 (RX+TX), TXU0204 (RX+CTS+TX+RTS), TXU0304 (SPI), or individual 74LVC1T45 in SOT23 (two for RX+TX, four for RX+CTS+TX+RTS), as I have done so and these have worked really well for me. I do prefer the TXU0n0m, because they have Schmitt trigger inputs (robust logic level input detection).I do also use 100nF = 0.1µF X7R or C0G/NP0 bypass capacitors between each VCC and GND (so two per TXU0n0m), as it ensures they work as promised in the datasheets; in practice, they may or may not be actually required. See Dave's video about bypass capacitors to understand why.For the cheapest possible solution, see my74LVC1T45-based RX+TX translator board(in Public Domain). It is absolutely tiny, 12.7mm × 12.7mm, and takes two 74LVC1T45W6-7 or SN74LVC1T45DBVR per board. You can have five or ten boards manufactured at JLCPCB for $2 + shipping, buy the LVC1T45 chips off LCSC or Mouser or elsewhere for a couple of USD/EURO, and solder them yourself. Just make sure you orient the pin 1 dot to the white silkscreen dot on the PCB, the two are rotated 180° with respect to each other. I also have aTXU0304 SPI translator, which would also work with TXU0204 as-is (but the silkscreen O3 and I3 would need to be swapped, and the corresponding arrow/triangles mirrored).Edited to add:Hereis the corresponding TXU0204 UART translator (all files in Public Domain). In addition to a TXU0204PWR (JLCPCB/LCSC C4363888, Mouser 595-TXU0204PWR), you need two 0.1µF = 100nF X7R capacitors in 0805 or 0603 footprint (perhaps Samsung CL21B104KBCNNNC in 0805, or CL10B104KB8NNNC in 0603)."
},
{
"post_id": "",
"author": "mr_byte31",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 05, 2024, 10:17:34 pm",
"content": "Many thanks for the reply. Highly appreciate it.I will definitely give a try to TXU0204 for UART.when you say that TXS0108E is perfect for I2C , do you know how could I fix my issue to make it work ? this issue is annoying me and I can't figure out any option.I have found other modules on internet that use BSS138 and few resistors to make the logic conversion. reference :https://www.adafruit.com/product/757do you believe this can be better option ?"
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 05, 2024, 11:47:56 pm",
"content": "Quote from: mr_byte31 on December 05, 2024, 10:17:34 pmMy sincere apologies: I absolutely forgot about that part! (Me fail, once again.)Did you forget the pull-up resistors?You see, I²C is anopen collectorbus, which is just a name for a bus where all devices on the bus can only pull the signal lines to ground. They cannot actually push or pull the signal line to any specific positive voltage. To ensure the signal lines are high, we need to use specific resistors.Note that only one resistor is needed per signal, i.e. one resistor between SDA and VCC, and one resistor between SCL and VCC. You do not need one resistor per signal per device; just one per signal line. (If you were using the 3Mbit/s or 5Mbit/s data rates, then it might be useful to use one resistor at each end of each signal line, twice the resistance of a single resistor, but those speeds are extremely rare in Arduino land.)The lower the resistor value, the more current runs in the signal wires (when pulled to ground). These resistors vary from 1k to 10k, with 2.2k most common. The smaller the current, the closer to ground the device can pull the signal line.When using bidirectional translators like TXS0108E for I²C, it is also important to realize that the signal line on each side of the TXS0108E requires their own pull-ups; the pull-up does not \"pass through\" the TXS0108E.To connect the MPU6050 to RPi, you need:Wire from RPi GND to MPU6050 GNDWire from RPi +3.3V to MPU6050 VCCWire from RPi SDA to MPU6050 SDAWire from RPi SCL to MPU6050 SCL2.2k resistor between SDA and +3.3V2.2k resistor between SCL and +3.3VWire this up, and test.To connect the ADC to RPi, use:Wire from RPi GND to TXS0108E GNDWire from RPi +3.3V to TXS0108E VCCAWire from RPi +5V to TXS0108E VCCBWire from RPi SDA to TXS0108E A3Wire from RPi SCL to TXS0108E A4Wire from RPi GND (or TXS0108E GND) to ADC GNDWire from RPi +5V (or TXS0108E VCCB) to ADC VCCWire from TXS0108E B3 to ADC SDAWire from TXS0108E B4 to ADC SCL2.2k resistor between RPi SDA (or TXS0108E A3) and +3.3V. (This is the same SDA resistor as in the previous test.)2.2k resistor between RPi SCL (or TXS0108E A4) and +3.3V. (This is the same SCL resistor as in the previous test.)2.2k resistor between ADC SDA (or TXS0108E B3) to +5V.2.2k resistor between ADC SCL (or TXS0108E B4) to +5V.I recommend you try the above separately first. When both work separately, you can combine them. Note that when combining, you only need four resistors, not six.Note that TXS0108E cannot supply much current on its outputs. If you want to switch power to peripherals on and off, you need something called a \"high-side switch\". For +3.3V, a single P-channel MOSFET suffices (I like DMP3099L for Arduino peripherals); for higher voltages, you need a P-channel MOSFET and either an N-channel MOSFET or NPN transistor. You'll also need a current-limiting resistor (for the GPIO pin –– MOSFET gates behave like capacitors, so when changing state, may draw uncomfortably much current from the GPIO pin, which the resistor limits to safe values, only slowing the switching action a tiny bit), and a pull-up/down resistor to set the state of the \"high-side switch\" when the GPIO pin is an input.Quote from: mr_byte31 on December 05, 2024, 10:17:34 pmThese have their own problems, especially switching speed. I consider them in the same class as other bidirectional voltage level translators.In general, I do like BSS138 (although I tend to use NX138AK instead, which is slightly faster switching, but otherwise almost identical, in three-pin SOT23 footprint) for my 2.5V to 12V signal-related N-channel MOSFET needs.I'm only a hobbyist myself, mostly using microcontrollers with native USB interfaces (like Teensy) to add user interfaces and other stuff to Linux-based SBCs and appliances like routers and TV boxes. I don't like the hardware compromises in USB implementations on the Raspberry Pis, and I don't like how the Foundation does not directly interface to the open source projects they rely on and insist hiding anything Linux or Open Source by their own naming schemes.It is exactly because of a lack of existing voltage translation modules for UART and SPI that I created my own. (The very first one I did, was one using two 74LVC1T46 IC's in SOT23 footprint, to interface a Teensy LC to the 1.8V UART on Odroid HC1.) After that, I noticed that when connecting separately-powered devices (like my desktop computer with a properly grounded supply) to other devices using wall warts (we have unpolarized \"Schuko\" sockets here; no live and mains, both are live, so ungrounded supplies 0V/GND level floats somewhere not even close to true ground), I was getting ground current loops (because their GNDs were at different potentials), and started using isolators too. (I particularly like TI ISO6721, which is very similar to TI TXU0102, allowing different supply voltages on each side, butalsoisolates the two GNDs.) Note, however, that I've beenridiculed for thathere, so I might be doing things wrong. I don't believe so, of course, based on the results I get.The Schmitt trigger inputs on the TXU0n0minputs also mean that when the GPIO pin they are connected to is floating (an input, during bootup when it is not yet configured as an UART pin), no excess current will flow. When the pin floats at an intermediate voltage (for 3.3V CMOS logic like RPi 4 uses, 0.8V and below is \"low\", and 2.0V and above is \"high\"; so between 0.8V and 2.0V in this case), and it is connected to the gate or base of a transistor, the transistor may be in its linear region, and instead of either fully conducting or non-conducting, acts like a resistor (with its resistance depending on the voltage on the gate; as described by its gate-source voltage to on-state resistance curve, if given, in the datasheet). That means it can waste power and generate excess heat. The Schmitt trigger inputs avoid all that, even if their output is used to control a transistor gate or base."
},
{
"post_id": "",
"author": "mr_byte31",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 06, 2024, 09:51:53 pm",
"content": "Many thanks for the answer.I am a bit confused when you use TXB0108E instead of my issue with TXS0108E.I checked datasheet for TXB0108E and I see it is not recommended for I2C. Please check attached figure.regarding TXS0108E, I checked the datasheet when I started my project and I understood that there is a smart pull-up resistors internally. The mentioned that external pull-up resistors are not required so I didn't connect any external pull-up resistors to both side of TXS0108E.Please check attached figure."
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 06, 2024, 11:36:06 pm",
"content": "Quote from: mr_byte31 on December 06, 2024, 09:51:53 pmJust a typo. (My concerns apply to both, though.) I did mean TXS0108E throughout, the I²C-appropriate one, just got the two mixed up. I've edited the post to avoid misleading/confusing others.See section 7.2 in the TXS0108E datasheet (PDF). The integrated pull-ups are equivalent to 4kΩ/40kΩ (depending on state, as they are active and not simply resistors), which may not be enough. I would definitely add external pull-up resistors, and do the tests, as I described. Only after the tests are successful, would I consider testing without the pull-up resistors.The exact pull-up strength (resistance needed) depends on the devices connected. Even in of the same PCB no pull-ups would be needed between TXS0108E and other devices, when you use wires the pull-ups may be necessary for a number of reasons, biggest reason being capacitively or inductively coupled noise. Adding external pull-up resistors means more current is used, which means such coupled noise affects the signal voltage less."
},
{
"post_id": "",
"author": "DavidAlfa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 06, 2024, 11:38:13 pm",
"content": "It'll probably work with pullups to 3.3V, skipping the level shifter entirely.Which ADC?"
},
{
"post_id": "",
"author": "mr_byte31",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 07, 2024, 07:49:44 pm",
"content": "I added 2K ohm pull-up to SDA and SCL on both sides (+3.3v and 5v )still the I2C is crazy and giving random values."
},
{
"post_id": "",
"author": "DavidAlfa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 07, 2024, 11:24:21 pm",
"content": "https://e2e.ti.com/support/logic-group/logic/f/logic-forum/909479/txs0108e-txs0108e-connected-i2c-devices"
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 08, 2024, 02:16:42 am",
"content": "Quote from: mr_byte31 on December 07, 2024, 07:49:44 pmSo, do what I suggested, and start by connecting the 3.3V MPU6050 directly to your RPi (with 2K pull-ups on both SCL and SDA), and see if that works.You see, right now there are dozens of places where the problem might be. It could be any of the hardware, even the RPi. Or it could be some kind of misconfiguration; perhaps you're using the wrong pins. (See the GPIO pin mapping in Linux to the pin labels on the RPi silkscreen.) You might be using the wrong Device Tree Overlay (say, one for RPi 2 instead of what you're using now).By doing things one step at a time, you limit the possible candidates, making troubleshooting much easier.By avoiding that, you're making it very difficult to find the actual problem. I don't like the\"throw spaghetti at the wall, and see what sticks\"approach (trying the easiest thing to see if it fixes the problem), and I don't like that you're refusing to test things one step at a time like any engineer or scientist or practical hobbyist should, and I suspect my posts are too long for you to bother to even read fully, so I will not waste both of our time any longer interacting with you. I do hope you solve your problem, though!"
},
{
"post_id": "",
"author": "mr_byte31",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 08, 2024, 02:12:03 pm",
"content": "Quote from: DavidAlfa on December 07, 2024, 11:24:21 pmI am aware about this topic and it is not working for me since the thread is based on wrong assumptions ( remove VCC_A)Quote from: Nominal Animal on December 08, 2024, 02:16:42 amMy devices on I2C ==> MPU is connected to 3.3v and I2C compass is connected to 5vLet me tell you what is the test cases I did:MPU(3.3v) connected directly to RPI with no pull-up: it works fineMPU(3.3v) connected directly to RPI with 2K pull-up : it worksMPU(3.3v) connected directly to RPI with 2K pull-up and TXS0108e connected to compass (5v): it doesn't workMPU(3.3v) connected directly to RPI with 2K pull-up and TXS0108e connected to compass (5v) and connected to 2K pull-up: it doesn't workMPU(3.3v) connected directly to RPI and connected directly to compass (5v) without pullup and without TXS0108e: it worksNote: RPI max voltage is around 4.5 and shall not be connected to 5v. I just did that to prove that all my configurations are correct and the issue starts when TXS0108e is in the middle."
}
] |
2025-10-17T16:26:42.689170
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(long-road-to-e-kart)-practical-information-about-making-high-power-circuits/
|
[Long road to e-kart] Practical information about making high power circuits? - Page 1
|
[
{
"post_id": "",
"author": "Ciel",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "February 27, 2025, 07:16:48 pm",
"content": "Hello peeps, Ive been learning electronics from the internet (ikr) on and off for a month now, and Im set an “ultimate goal” so to say to build a 5/10kW electric kart? golf car? some kind of LEV with two pmsm motors and a custom controller/driver. But Im sure I have plenty to go before I should be working with either 100+V or A. I was also insistent on using sodium ion cells for some reason so there’s also challenges that come with that(72V pack goes from 95V max to 36V cutoff lmao, but ofc I don’t need to always extract everything)I know basic electricity from studying physics in HS, and some design patterns and parts from strolling around the net, including a great series about BLDCs from Jantzen Lee, which taught me a lot of higher level concepts about controlling BLDCs(well, PMSMs but theyre similar), but there seems to be little in the way of more practical information about handling higher power currents through the pcb or how to connect to the thicc bolt terminal things, probably because it’s much harder to get right just for a video. I did find an EV inverter teardown video from DENKI OTAKU and that gave me some good ideas, but the details are still pretty faint. Im also slowly going through MIT’s 6.002 Circuits and Electronics(2007) on OCW though that’s more fundamental(and has countable number of pixels), maybe I should move to 6.622 Power Electronics (2023).So in a way Im asking for two things here, for one Im looking for some resources to learn about the specifics of dealing with high power, safety and execution wise. Like Im looking for MOSFETs and they barely go above 100A from TI and seems to be limited to 200A by the leads from Infineon so Im not sure how to get some more safety margins, maybe the way is to parallel them? But that seems like a different set of wormholes. Overall I just don’t feel… comfortable? confident? with power electronics yet as I am with lower power, like I don’t know how to design a pcb specifically but I can’t be *that* much off, I feel like I can always get it working even if I need to hack it, at least I know what to hack. But with high power, I’m just clueless, like there are things that I have zero idea on what to do like connecting the components, I feel that I am missing still some crucial pieces of information to make it all “click”.On the other hand, I would also love y’alls opinion on what I can do to prepare myself up to this big project. I got a gimbal bldc already because I wanted to make the SmartKnob, maybe I should do this first? What should I do next?Also I should mention that I haven’t gotten a power supply or oscilloscope yet(other than an USB oscilloscope and a low? current .5A multi-voltage board) but I’ll get them soon when I get a space in a few months(space constraints in my home). I do have a decent multimeter and soldering setup though if that counts for anything. And since I mentioned this, equipment advice is also welcome lol.Sorry in advance if anything was hard to understand, Im very bad at writing long passages and it can become decoherent."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 01, 2025, 03:47:01 pm",
"content": "Since you got no responses I'll try.Your question is like saying to a musician that you want to write a symphony but you just need some help with the notes. I think having an eventual goal to build an electric cart is good goal. Here are perhaps some ways to learn. It will be a long road.Look at similar equipment and see how they're wired an built. The fancy name for this is reverse engineering.You might buy a broken cart or kiddy car or electric wheelchair and get it going.There is a good book called \"Practical Electronics for Inventors\" by Shertz. Its in the right area for your needs.As far as high current wiring, approach it from ohm's law that you got in HS physics. V=IR, P=I^2R,R= rho*L/A (rho resistivity is 1.7e-8 for copper). To move 100 + amp currents, you need 50 mm^2 area wire (7 mm diam). This is from standard tables from the National Electric Code. You can calculate what the total power dissipated in this wire would be with those equations.Your question is very difficult to answer but I guess it comes down to dedicate yourself to the problem and learn."
},
{
"post_id": "",
"author": "Ciel",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 01, 2025, 08:25:35 pm",
"content": "Thank you for the response, I know that I am far from my goals and I am inching(centimetering?) away at it. I think I will get a controller and disassemble it, it can also come in handy for testing, I had been thinking about it for a bit but it’s quite expensive for a nice one. I was planning on buying a small wheeled robot for a more robotics focused project of mine as well and I was planning on taking a peak inside.Regarding the high current part, yeah I know I need really thick wires but that’s easy to do, the more burning question I have is how to get them onto a PCB without obliterating everything, high power mosfets/gan fets like to come in tiny packages cause parasitic capacitance and loop something that I forgot the name of, so there has to be a transition from “thicc wire” to pcb traces which uhh, R=ρ l/A doesn’t have the best A… and the 2221 standard tell me I need 30cm traces(iirc and it’s said it’s not applicable at this scale) so that’s probably not gonna work out, what is that missing link of “getting the huge amount of current onto a pcb, into the mosfet, and out of it? How do I ensure the traces dont turn into copper soup? Either my wording or idea is wrong because somehow I had been able to find zero information talking about this, at most mentioning in passing.Also thanks for the book recommendation, Ill look into it."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 02, 2025, 01:00:41 am",
"content": "If you take apart some car audio stuff or a hefty DC to AC inverter- you can see how they do it. You use very beefy PCB and very wide tracks. Board materials come in different copper weights- standard JLPCB stuff is 1 oz (weight/square foot)- this works out to 35 microns or about 1.3 mils thick. But it goes up from the there- I've done work with 10 oz and I think there is larger- this 10 oz stuff would .013\". A 2 inch track of this would have have an area of .026 in^2, that will do 100 amps if you go through the numbers or look at ampacity tables. Sometimes you'll see the high current area flowed over with extra solder- lead is a decent conductor- 10x worse than copper on rho but decent. This is common in audio stuff. Often they will screw the board down to copper bus bars to get off the board and act as input terminals. In cheap stuff, they use big ring lugs with large nuts, washers and bolts to the board. There are also connectors for this stuff that you'll see on tow trucks or electric forklifts- 200 amp is pretty standard. Solar installs have proliferated these high current connectors and there are some pretty nice ones. Its just ohms law. Milliohms turn into watts at these currents (squared). You can look at the specific heat of copper and see what 5 watts would do to a cubic inch... Physics all the way down.There are tons of tables and guides for all this stuff, you don't have to go back to first principles but its not a bad idea to derive it once at least. I googled and found Storm Power that has nice resources on line. Have fun, get off the computer, go buy some junked power stuff and get some burns, that's is how you'll learn.https://stormpowercomponents.com/technical-library/ampacity-and-specifications-tables/copper-alloy-c11000-busbar-ampacity-chart/Use the thanks button, its how I measure my worth to the world."
},
{
"post_id": "",
"author": "Konkedout",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 02, 2025, 01:23:21 am",
"content": "I have been design engineering electronics for almost 50 years, and I have a couple of observations:1) I recommend starting with lower power. Not sure what sort of thing to recommend but if you want to do electric locomotion then maybe do an R/C toy car.2) The greatest schematic diagram in the world will be garbage if the pcb layout is not good. A good pcb layout is critical and its importance cannot be overstated. In order to do a good pcb layout, you really need to understand what is going on.Bypass capacitors generally should be the first components placed/connected to many ICs, but newbies will typically postpone or ignore that.Check out any application notes (previously LT but now ADI) discussing \"hot loops\". I am sure that TI and other manufacturers also discuss the issue but theyprobablydo not call it a \"hot loop\".Those are just the first two items that come to mind dealing with circuitry and power."
},
{
"post_id": "",
"author": "Smokey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2025, 03:48:42 am",
"content": "Buy at e-kart kit if you want an e-kart.Just for a frame of reference, it would take a team of professional power electronics engineers quite some time (and money) to design and build what you are describing and have it work reliably. Every part of this is hard."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 02, 2025, 05:42:10 am",
"content": "Of course you're right- I don't think he really wants an E-Kart- he wants to dream about making one. It really isn't about what makes any sense in a rational sense, this is aspirational. I won't say it out loud, but its very likely, that this dream will never be realized. That's not the point either. Its just about thinking about this thing with a Sodium Battery that does things. Its beautiful.I have a dream to make an electric boat- I could buy one, likely better than my imagined object but it doesn't matter much either. It won't happen but I won't admit that.We are on earth to dream and strive- most dreams are never realized- this is ok."
},
{
"post_id": "",
"author": "voltsandjolts",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 02, 2025, 09:41:22 am",
"content": "search \"formula student electric\""
},
{
"post_id": "",
"author": "eTobey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2025, 10:16:33 am",
"content": "The way to success start with a small step.If you have some electronics knowledge, start with a small project. Parts are cheaper, and not that dangerous, if they blow up. (still dangerous with certain battery types)."
},
{
"post_id": "",
"author": "Ciel",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 03, 2025, 04:37:49 pm",
"content": "Quote from: Konkedout on March 02, 2025, 01:23:21 amThank you for the insight! I'll be looking out in terms of PCB design.I think I mentioned in a previous reply but I was planning on getting what is kind of a bigger RC car for a separate reason anyway, it'll probably be a lot of quality learningDo you mind linking to these \"application notes\" so I know what kind of documents I should be looking out for? Thanks"
},
{
"post_id": "",
"author": "Ciel",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 03, 2025, 04:43:36 pm",
"content": "Quote from: jwet on March 02, 2025, 05:42:10 amQuote from: Smokey on March 02, 2025, 03:48:42 amI did look a bit into FSAE/Formula Student info, and I know it's a ton of work to get an actually good kart and/or with compliance to join races and stuff. But my goal wasn't to make a good kart anyway, go-kart is just the form factor, really I just want to make some kind of high power thing and go vroom XD. Of course jumping to it is probably not the best idea, but I do aim to realize it no matter how unusable is turns out, just like a lot of other expensive toys I got lol. How does the saying go? You don't grow up, your toys only get bigger :p."
},
{
"post_id": "",
"author": "Smokey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 03, 2025, 07:57:30 pm",
"content": "You may find that electronics of this power level do not exist on a \"continuum of functionality\" that goes linearly from not-working to working with all manner of partially-working in between.Roughly speaking, Power electronics at this level are either working or blowing themselves up."
},
{
"post_id": "",
"author": "Ciel",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 04, 2025, 05:25:20 am",
"content": "Quote from: Smokey on March 03, 2025, 07:57:30 pmGood to know, thank you for the advice"
}
] |
2025-10-17T16:22:16.199523
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(math)-solving-circuit-analysis-problems/
|
[Math] Solving circuit analysis problems - Page 1
|
[
{
"post_id": "",
"author": "nForce",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 04, 2018, 02:14:38 pm",
"content": "Hi,this topic will be a little refresh of math and circuit analysis. The first circuit is here:Here U = Voltage.How do we get U_1? I know that here is used a voltage divider, but I can't see it.More problems to come"
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 04, 2018, 03:08:22 pm",
"content": "I get the feeling that there is more to the original question that you are telling us.With the given diagram, my first step would be to write-down the impedance for the parallel combination of \\$L\\$, and \\$R + Z_b\\$."
},
{
"post_id": "",
"author": "nForce",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 04, 2018, 03:27:08 pm",
"content": "I forgot to mention that L and R are inside two-port network. Those circles are contacts. Does this help you?"
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 04, 2018, 05:33:35 pm",
"content": "Quote from: nForce on January 04, 2018, 03:27:08 pmOnly to confirm my suspicions that there is more to this question than you have shownYou asked \"how do we get \\$U_1\\$. Since an equation for \\$U_1\\$ is given I assume you want to know how to get that equation?As I said, my first step would be to find the impedance of the parallel combination of \\$L\\$ and \\$R + Z_b\\$ using the short-cut \\$Z_p = \\frac{Z_1 Z_2}{Z_1 + Z_2}\\$. If you put \\$Z_1 = R + Z_b\\$ and \\$Z_2 = j \\omega L\\$, I think we have:$$Z_p = \\frac{(R + Z_b) j \\omega L}{R + Z_b + j \\omega L}$$Now you have your divider of \\$Z_g\\$ and \\$Z_p\\$ - plug those into the first equation given and the equation for \\$U_1\\$ readily drops out.However, the diagram is labelled with \\$I_1, I_2\\$ and \\$U_2\\$ which leads me to suspect that the original question also specified a method for the solution (e.g. \"using Kirchhoff/Thevenin/nodal analysis, \"... or whatever), and now you mention \"two port network\"."
},
{
"post_id": "",
"author": "MrAl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 04, 2018, 06:53:28 pm",
"content": "Hi,I agree with Andy, if you want to see how this works you would first collapse the right side of the network into one impedance Zx, then use that in the voltage divider formula:U1=Ug*Zx/(Zx+Zg)Now you are also in a position to calculate the output U2 using a second application of the voltage divider formula:U2=U1*Zb/(Zb+R)You dont have to do it that way though. That's a \"reverse collapse\". You can go forward (left to right) by using Thevenin and Norton source transformations."
}
] |
2025-10-17T18:41:22.623708
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(mini)oscilloscope-advice/
|
(Mini)oscilloscope advice - Page 1
|
[
{
"post_id": "",
"author": "quicknick",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 14, 2021, 05:47:46 pm",
"content": "Hello everyone,Retro computing junkie here, feeling more and more the need for a simple and small oscilloscope. Kept postponing it, but after seeingthis videoI'm determined to pull the trigger so that 2022 doesn't find me oscilloscope-less.So, what I expect from it? To be able to measure and display usual frequencies found on old PC boards (dunno if the unit from the above video passes this test, as it seems to display a sine wave instead of a (mostly) square one - maybe bandwidth is too limited?), and also to measure ripple (PSU rails, CPU/GPU/RAM VRM).Handheld units as the one from above are strongly favored, but I'll consider other options too. Target price would be around 100 ($/EUR) but can go higher (200 max) if the features justify it (or if it's impossible to find what I need at target price).Thanks!"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 14, 2021, 06:01:18 pm",
"content": "My advice - don't. Video editing does not show the frustration of trying to find a trace on that toy. Button interface for scopes never works (or at least I have not seen a good implementation that works).Something like Hantek DSO2C10 or OWON SDS1102 are quite cheap (not as cheap as those handhelds, of course) and compact. They are also real tools with decent performance for the price."
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 14, 2021, 09:38:47 pm",
"content": "I agree with ataradov here.It's a toy that has too many limitations to be used in a decent way and it will very likely end up in the bottom of a drawer because of it's limitations and because its so annoying to use.Another review of this thing: EEVblog #1260 - $70 100MHz Oscilloscope?This other Fnirksty is also too much rubbish to be worth looking at:EEVblog #1317 - $140 2CH 100MHz Fnirsi Tablet Oscilloscope ReviewThat brand also makes a gadget in a \"normal scope form factor\", but if you take those other two as any indication then I fear the worst. That brand does not even try to make something useful, it just makes toys that look acceptable on paper and in shallow reviews.I'd say just don't buy that brand. Maybe they are capable of making something decent in 10 years time.All those mini scopes have a pretty cumbersome user interface.If you really want such a small (and battery powered, which can be an advantage) scope, then have a look at:Hantek 2D72 vs. OWON HD272S – Which Scopemeter is Better?Those do have two channels, so you can compare input and output of a circuit to each other.They are also a bit less cheap, but the price difference between those and a scope in a \"normal form factor\" is becoming quite small, and those bigger boxes have a much better user interface."
},
{
"post_id": "",
"author": "quicknick",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 15, 2021, 12:22:52 am",
"content": "Thank you both!As usual, one look down the rabbit hole, and suddenly I realize how little I know on the subject!I started by watching the 2D72 vs. OWON HD272S video, at the end I was quite convinced about the Owon, but after that went and watched a video on the SDS1102 and boy, does a \"proper\" oscilloscope make those handhelds look like toys...A comment at the end of the handhelds review got me worried: \"Also minimum v/div is too high making it impossible for low voltage or noise measurements.\" - not sure if I wholly understand, but does this make them unsuitable for measuring ripple/noise on power rails? Also, what is the importance of protocol decoding?Another issue (although it shouldn't be a problems in most of the measurements I'll need to take) - am I right in assuming that the ground of the probe is connected to the safety earth in mains powered scopes?"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 15, 2021, 12:50:33 am",
"content": "The little handheld scopes are essentially just toys. They are marginally better than no scope at all but I would not want to have to get by with one. IMO you are better off saving your money up until you can afford something like a Rigol or other budget DSO, they are larger than handheld but still quite compact. If that is really too much of a stretch then you could look for an older used scope and pick up one of those.There is a saying that applies here \"buy cheap, buy twice\", I think if you buy a cheap handheld you will quickly outgrow it and decide you need something better, hence it is cheaper in the long run to spend a bit more.It might help to know what you actually intend to accomplish with the scope though. \"Measure and display waveforms on old PC boards\" could mean different things. It sounds like perhaps all you want is a toy? If that's the case then sure, you will be able to see waveforms, but what's that going to do for you? You may be better off learning more about oscilloscopes, how they are used and for what applications before you spend any money. Having a scope without having a solid understanding of what to do with it is not really going to help you much, unless you just want to play around."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 15, 2021, 01:07:54 am",
"content": "Quote from: quicknick on October 15, 2021, 12:22:52 amOn the chapos you mostly measure weather in Africa on low v/div settings anyway.SDS1102 has 50 mV/div lowest setting. It is not ideal, but usable for ripple that may affect digital electronics.Quote from: quicknick on October 15, 2021, 12:22:52 amNot at all, especially on low end scopes. On the toy scopes it is even bigger joke. Get a cheap USB logic analyzer and your life would be instantly better.Quote from: quicknick on October 15, 2021, 12:22:52 amYes, in most cases."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 15, 2021, 09:51:20 am",
"content": "If you need portability, get the OWON DS7102V, with the battery option. It's more expensive, but the nice big screen is worth it. Note that it shouldn't be used above 25VAC, or 60VDC, when run of the battery and unearthed. Never use on the mains."
},
{
"post_id": "",
"author": "dophuc",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 16, 2021, 09:49:07 am",
"content": "I have a handheld oscilloscope (OWON HDS242, 2CH/ 40Mhz + DDM 20,000 counts) and a 4CH oscilloscope (Siglent SDS 1104X-E). I bought Owon for only about $120 and I really like it. The oscilloscope function is simple but quite useful. DDM function can measure resistors, diodes, capacitors..."
}
] |
2025-10-17T17:21:11.896868
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(most)-simple-regen-am-receiver-confused-about-the-feedback-circuit/
|
(Most) Simple "Regen" AM receiver - confused about the feedback circuit - Page 1
|
[
{
"post_id": "",
"author": "AxelGreen",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "February 26, 2019, 09:40:50 pm",
"content": "Hi everyone !I'm sorry to soil this forum with such a question ! I'm majoring in math (first year at Uni in France), but happened to love electronicsI can't fathom why (in many regen receivers and particularly this one, see attachment) the signal reenters the LC filter through the middle of the coil. I intuitively understand that it cannot but increase the quality factor but I'm a bit at loss on how to handle the analysis of this circuit.Couldn't this parallel LC filter be replaced with a series LC filter, filtering directly the signal from the emitter of T1 ?Is there any induction from one part of the coil to another ? (this is one single coil, the wire from T1 being placed at the fifth turn from the gnd). Or is it just an electrical way to get the signal back into the filter ?Thanks a lot and sorry for my terrible English !"
},
{
"post_id": "",
"author": "Paul Rose",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "February 27, 2019, 12:29:51 am",
"content": "Your English is good, and regen radios are fun.It would help if you posted a link to (or copy of) an example schematic.You are right that taking the feedback from a tap is about keeping the Q of the overall tank circuit high ( loading it less ).There are other schemes ( often seen in older vacuum tube designs ) where they get the feedback from a separate coil with fewer windings, but wound on the same form.Yes, there is mutual coupling.You can model either case ( tapped coil or separate coild ) in something like LtSpice. Place two inductors with appropriate inductance. To model a tapped coil, connect the \"dotted\" end of one to the plain end of the other. You may have to enable something in the inductor's properties to show phase dots. Then set the coupling factor between the inductors to something high ( like 1.0 ). Use a spice \"K\" directive to set the coupling ( example \"K La Lb 1\" ).You might get more responses in the \"RF, Microwave, Ham Radio\" section of this forum."
},
{
"post_id": "",
"author": "Paul Rose",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "February 27, 2019, 04:42:39 am",
"content": "OK, found this schematic, which is reasonably easy to understand.The collector-emitter voltage drives the top half of the coil. Note that the emitter is AC coupled to the center tap.The feedback into the base of the transistor is taken from the bottom half of the coil.When the top of coil swings positive with respect to the center tap, the bottom of the coil swings negative ( again with respect to the center tap ). This is due to the coupling between the top half and bottom half of the coil.But the collector-emitter voltage swings opposite to the base drive ( more base current = more collector current, so the collector-emitter voltage is lower ).So the net effect is positive feedback. The circuit \"wants\" to oscillate.But you cut the gain by adjusting R2 so that it doesn't quite oscillate."
}
] |
2025-10-17T18:15:44.040488
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(msp430f5529-ili9341-screen)-command-instruction-seem-dont-works/
|
[SOLVED] [MSP430F5529 + ili9341 screen] command instruction seem don't works - Page 1
|
[
{
"post_id": "",
"author": "OrKaraz",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 21, 2021, 09:26:20 am",
"content": "Hi,Since few days i'm working on a screen project with my MSP430F5529 and one ili9341 screen.I have take an exemple (from arduino, can't find on MSP) and adapt it to know how use the screen.After few try, i can fill the screen with colors but can't draw a simple line or rectangle at a special position.When i run the program step by step, all instruction command work and on the screen i have all the program what have to do.I have try to change all wire but no change.The MSP430F5529 run at 25 MHz (max) with 3.3V like the screen.Code://This application does not rely on any libraries and it is for ILI9341//This program is a demo of clearing screen to display black,white,red,green,blue.//when using the BREAKOUT BOARD only and using these hardware spi lines to the LCD,//the SDA pin and SCK pin is defined by the system and can't be modified.//if you don't need to control the LED pin,you can set it to 3.3V and set the pin definition to -1.//other pins can be defined by youself,for example//pin usage as follow:// CS DC/RS RESET SDI/MOSI SCK LED VCC GND// GND//Remember to set the pins to suit your display module!#include <msp430.h>#define FPROC 25000000/*P3.0 : MOSIP3.1 : MISOP3.2 : CLK*/#define RSUP P6OUT|=BIT0 // DC/RS#define RSDOWN P6OUT&=~BIT0#define LEDUP P6OUT|=BIT1#define LEDDOWN P6OUT&=~BIT1#define CSUP P6OUT|=BIT2#define CSDOWN P6OUT&=~BIT2#define RESETUP P6OUT|=BIT3#define RESETDOWN P6OUT&=~BIT3unsigned long oldrand = 5468;void SetVcoreUp (unsigned int level){// Open PMM registers for writePMMCTL0_H = PMMPW_H;// Set SVS/SVM high side new levelSVSMHCTL = SVSHE + SVSHRVL0 * level + SVMHE + SVSMHRRL0 * level;// Set SVM low side to new levelSVSMLCTL = SVSLE + SVMLE + SVSMLRRL0 * level;// Wait till SVM is settledwhile ((PMMIFG & SVSMLDLYIFG) == 0);// Clear already set flagsPMMIFG &= ~(SVMLVLRIFG + SVMLIFG);// Set VCore to new levelPMMCTL0_L = PMMCOREV0 * level;// Wait till new level reachedif ((PMMIFG & SVMLIFG))while ((PMMIFG & SVMLVLRIFG) == 0);// Set SVS/SVM low side to new levelSVSMLCTL = SVSLE + SVSLRVL0 * level + SVMLE + SVSMLRRL0 * level;// Lock PMM registers for write accessPMMCTL0_H = 0x00;}// fonction aleatoireunsigned int random(unsigned int n) {unsigned long nn = oldrand;oldrand = (unsigned int)((859*nn)%6823);return oldrand % n;}void delay(unsigned int i){while(i--)__delay_cycles(FPROC/1000); // 1000 for 1MHz}// envoyer sur le SPI la donnéevoid Lcd_Writ_Bus(unsigned char d){while(UCB0STAT&BIT0) {} // si la communication n'est pas finie on attendUCB0TXBUF = d;}// écrire la commandevoid Lcd_Write_Com(unsigned char VH){RSDOWN; //LCD_RS=0;Lcd_Writ_Bus(VH);}// écrire la donnéevoid Lcd_Write_Data(unsigned char VH){RSUP; //LCD_RS=1;Lcd_Writ_Bus(VH);}void Address_set(unsigned int x1,unsigned int y1,unsigned int x2,unsigned int y2){Lcd_Write_Com(0x2a);Lcd_Write_Data(x1>>8);Lcd_Write_Data(x1);Lcd_Write_Data(x2>>8);Lcd_Write_Data(x2);Lcd_Write_Com(0x2b);Lcd_Write_Data(y1>>8);Lcd_Write_Data(y1);Lcd_Write_Data(y2>>8);Lcd_Write_Data(y2);Lcd_Write_Com(0x2c);}void draw_pixel (unsigned char cr,unsigned char cv,unsigned char cb) {Lcd_Write_Data(cr);Lcd_Write_Data(cv);Lcd_Write_Data(cb);}void SPI_Init(void){UCB0CTL0 = BIT7 | BIT5 | BIT3; // Master + MSBfirst + front montant + CLK inactif 0UCB0CTL1 = BIT7 | BIT6; // SMCLKP3SEL |= 0x07; // on utilise le SPI (CLK, MOSI et MISO)}void Lcd_Init(void){RESETUP;delay(5);RESETDOWN;delay(15);RESETUP;delay(15);CSDOWN; //CSLcd_Write_Com(0xCB);Lcd_Write_Data(0x39);Lcd_Write_Data(0x2C);Lcd_Write_Data(0x00);Lcd_Write_Data(0x34);Lcd_Write_Data(0x02);Lcd_Write_Com(0xCF);Lcd_Write_Data(0x00);Lcd_Write_Data(0XC1);Lcd_Write_Data(0X30);Lcd_Write_Com(0xE8);Lcd_Write_Data(0x85);Lcd_Write_Data(0x00);Lcd_Write_Data(0x78);Lcd_Write_Com(0xEA);Lcd_Write_Data(0x00);Lcd_Write_Data(0x00);Lcd_Write_Com(0xED);Lcd_Write_Data(0x64);Lcd_Write_Data(0x03);Lcd_Write_Data(0X12);Lcd_Write_Data(0X81);Lcd_Write_Com(0xF7);Lcd_Write_Data(0x20);Lcd_Write_Com(0xC0); //Power controlLcd_Write_Data(0x23); // 23 VRH[5:0]Lcd_Write_Com(0xC1); //Power controlLcd_Write_Data(0x10); //SAP[2:0];BT[3:0]Lcd_Write_Com(0xC5); //VCM controlLcd_Write_Data(0x3e); //ContrastLcd_Write_Data(0x28);Lcd_Write_Com(0xC7); //VCM control2Lcd_Write_Data(0x86); //--Lcd_Write_Com(0x36); // Memory Access ControlLcd_Write_Data(0x48); // 48 (28 -> mode paysage, 48 -> mode portrait)Lcd_Write_Com(0x3A); // Pixel format setLcd_Write_Data(0x66); // 55Lcd_Write_Com(0xB1);Lcd_Write_Data(0x00);Lcd_Write_Data(0x18); // 18Lcd_Write_Com(0xB6); // Display Function ControlLcd_Write_Data(0x08);Lcd_Write_Data(0x82); // 82Lcd_Write_Data(0x27);Lcd_Write_Com(0x11); //Exit Sleepdelay(120);Lcd_Write_Com(0x29); //Display onLcd_Write_Com(0x2c);CSUP;}void H_line(unsigned int x, unsigned int y, unsigned int l,unsigned char cr,unsigned char cv,unsigned char cb){unsigned int i;CSDOWN;Lcd_Write_Com(0x02c); //write_memory_startAddress_set(x,y,l+x,y);for(i=1;i<=l;i++){draw_pixel(cr, cv, cb);}CSUP;}void V_line(unsigned int x, unsigned int y, unsigned int l,unsigned char cr,unsigned char cv,unsigned char cb){unsigned int i;CSDOWN;Lcd_Write_Com(0x02c); //write_memory_startAddress_set(x,y,x,l+y);for(i=1;i<=l;i++){draw_pixel(cr, cv, cb);}CSUP;}void Rect(unsigned int x,unsigned int y,unsigned int w,unsigned int h,unsigned char cr,unsigned char cv,unsigned char cb){H_line(x , y , w, cr, cv, cb);H_line(x , y+h, w, cr, cv, cb);V_line(x , y , h, cr, cv, cb);V_line(x+w, y , h, cr, cv, cb);}void Rectf(unsigned int x,unsigned int y,unsigned int w,unsigned int h,unsigned char cr,unsigned char cv,unsigned char cb){unsigned int i;for(i=0;i<h;i++){H_line(x , y , w, cr, cv, cb);H_line(x , y+i, w, cr, cv, cb);}}void LCD_Clear(unsigned char cr,unsigned char cv,unsigned char cb){unsigned int ii,mm;CSDOWN;Address_set(0,0,240,320);for(ii=0;ii<240;ii++)for(mm=0;mm<320;mm++){draw_pixel(cr, cv, cb);}CSUP;}void LCD_Arc(){unsigned int ii,mm;unsigned char cb = 0, cv = 0, cr = 0;CSDOWN;Address_set(0,0,240,320);for(ii=0;ii<320;ii++) {if (ii<80) cr=3*(ii%80);else if (ii<160) cr=3*(80-(ii-80)%80);else if (ii<240) cb=3*((ii-160)%80);else cb=3*(80-(ii-240)%80);for(mm=0;mm<240;mm++){cv = mm%240;draw_pixel(cr, cv, cb);}}CSUP;}void LCD_Carre(){unsigned int ii;CSDOWN;Address_set(10,10,20,20);for(ii=0;ii<100;ii++) {draw_pixel(0xff, 0xff, 0xff);}CSUP;}/*** main.c*/void main(void){WDTCTL = WDTPW | WDTHOLD;// stop watchdog timerSetVcoreUp(1);SetVcoreUp(2);SetVcoreUp(3);UCSCTL3 |= SELREF_2; // Set DCO FLL reference = REFO (32 768)__bis_SR_register(SCG0); // Disable the FLL control loopUCSCTL0 = 0x0000; // Set lowest possible DCOx, MODxUCSCTL1 = DCORSEL_5; // Select DCO range 25MHz operationUCSCTL2 = FLLD_0 + (FPROC/32768 - 1); // Set DCO Multiplier for 25MHz (487 pour 16MHz) (761 pour 25MHz)// (N + 1) * FLLRef = Fdco// (761 + 1) * 32768 = 25MHz// Set FLL Div = fDCOCLK__bic_SR_register(SCG0); // Enable the FLL control loopthen select clock source by write SPI control register (UCSSELx)UCSCTL4 |= SELA_3; // présence de MCLK/1024 sur P1.0UCSCTL5 |= DIVPA_5 | DIVA_5;P1DIR |= BIT0;P1SEL |= BIT0;SPI_Init();P6DIR |= 0x0F; // bit0 à 3 en sortieRSUP;LEDUP;CSUP;RESETUP;Lcd_Init();while (1) {LCD_Clear(0xff, 0xff, 0xff);delay(1000);LCD_Clear(0xff, 0x00, 0x00);delay(1000);LCD_Clear(0x00, 0xff, 0x00);delay(1000);LCD_Clear(0x00, 0x00, 0xff);delay(1000);LCD_Arc();delay(3000);LCD_Carre();delay(5000);LCD_Clear(0x00, 0x00, 0x00);Rect(10,10,100,50,random(256),random(256),random(256));/*for(i=0;i<100;i++){Rect(random(239),random(319),random(239),random(319),random(256),random(256),random(256)); // rectangle at x, y, width, hight, color}*/delay(5000);}__bis_SR_register(LPM4_bits);}Thank you for help."
},
{
"post_id": "",
"author": "mayor",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 21, 2021, 11:53:18 am",
"content": "Pasting the entire program makes it difficult to help. Can you paste a minimal working example (filling the screen), and a minimal non-working example (a line) ?"
},
{
"post_id": "",
"author": "OrKaraz",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 21, 2021, 01:20:32 pm",
"content": "Hi,All the program is minimum.After more research when waiting this answer (16h i search it) i have find the probem.To me : never use any more --opt_level 3 or 4.Don't know why, but the \"P6OUT &= ~BIT0\" instruction was not working in --opt_level 4 nether 3. (line 84)I have set to 2 and now all works like it does to be.Now i'll able to use ASM.Thank you for answering."
}
] |
2025-10-17T17:35:11.686121
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(my)-casual-product-review-a-tech-play-mp3-and-phonograph-record-player-!/
|
(My) Casual Product Review, A Tech Play MP3 and Phonograph record player ! - Page 1
|
[
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 03, 2025, 09:54:17 pm",
"content": "Hi All : I like to post in BEGINNERS section because we are about learning and analyzing existing products...before hopefully doing our own.This time I've gotten my grubby hands on a FLEA MARKET or dump recycled record player, or at least I thought, until I got it home. It's an MP3 / record / tape cassette / SD machine...and it powers up !!!Pictures on the way. First assumption was the thing got thrown in the dump trash, maybe due to some hopefully minor fail. But the 12 Volt wall wart worked, (once I moved my multimeter lead off from 'AMPS' and plugged into the 'V/hz' banana jack...duhuh...)This bedside super-alarm-clock radio costs around $100 at Walmart, Amazon, etc.Heck, I just needed the piezo sensor stereo needle, and would have been happy to convert to my Acoustic Guitar; a blast in itself, converting to '5 string' trimmer line BARITONE - BASS, in my rig.(more soon)Thanks for reading !"
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 17, 2025, 03:27:46 pm",
"content": "That's funny. I have a 35 year old son and he and his friends are very into Vinyl these days. He regularly comes over and raids my dusty 80's record collection. Used turntables and records are getting valuable here in the US with this generation. There are allways these funny products that appear during any technology transition. I had a funky VCR that could copy tapes to DVD's- not such a bad idea but a rare find."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 17, 2025, 07:45:14 pm",
"content": "Quote from: jwet on July 17, 2025, 03:27:46 pmYes, vinyl is here to stay. Unlike CDs, apparently.Now, with no disrespect to the OP (Rick) or to his dumpster-diving discovery, that all-in-one LP/cassette/MP3 thing is, unfortunately, pretty much a piece of shit when it comes to the record-playing part.Meaning it will actually probably damage your LPs when you play them on it. Probably has a cheap ceramic (piezoelectric) cartridge, not the better and more compliant magnetic cartridge found on better turntables. Plus minimal or no counterbalancing of the tone arm, and no anti-skating.One could certainly use something like that to play scratched-up old yard-sale/thrift-store LPs that one doesn't really care about, but not one's pristine, carefully-kept-clean LPs. And, no, I'm no audiophool: just like to keep my record collection (currently ~500 or so discs) sounding as good as possible.Good turntables are harder to find these days than junk phonos like the one Rick found, but they are still out there. Any separate turntable, including the low-end Garrards, BSRs, etc., will be better than his find. Of course, you'll then need an amp and speakers. (Could easily build a small one to drive headphones, to keep with the hobbyist angle here.)But hey, it's good to find a (maybe working?) pornograph*in the trash, and I wish him the best of luck with it.*Anthony Perkins' Freudian slip in Orson Welles'The Trial; great flick."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 19, 2025, 09:18:32 pm",
"content": "Quote from: Analog Kid on July 17, 2025, 07:45:14 pmNo, No! CD's are coming back too!- I guess people are getting tired of all the MP-3, lossy encoded, streaming, Pandora and Spotify junk. Neil Young was right as usual- he had a real beef with the streaming services. Now that you can get Terabyte drives for a few bucks and download at a gig/sec, who needs compression? People are re-ripping their CD collections with FLAC (3:1 lossless) or just straight PCM. Time was when 660M sounded like a lot but I can record 1000 CD's complete raw on a $50 disk. The only problem with ripping all that music is that everyone sold off or threw out their CD collections. I've been listening to 128K MP-3's so long, I'm kind of lost. I do listen to CD's still and they do sound better...If I live long enough, we'll probably see the return of cassettes and 8 tracks. Cassettes could muster 70+ db kind of number but 8 Tracks were hopeless. Its still an Analog World (spoken as a Maxim retiree after 25 years)Take care."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 19, 2025, 09:34:46 pm",
"content": "Quote from: jwet on July 19, 2025, 09:18:32 pmThere seem to be plenty of places to acquire CDs these days. Thrift stores have them by the thousands; yard sales, even put out in the trash sometimes.Town I live in has a record store (vinyl!) that also sells CDs and cassettes; lots and lots of them. They're doing a roaring business.I recently ripped a cassette I had from decades ago of a performance (symphony orchestra) that I played in. I was absolutely astounded by the quality of the recording; much better than I would have thought. Plenty of dynamic range and HF reproduction. It's a much underrated medium.I actually have an 8-track player (Pioneer) that someone gave me and I haven't even tried out yet; chances are that it works and only needs cleaning and a lube. Then I can look for all the trucker tapes to play on it ..."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 19, 2025, 09:54:43 pm",
"content": "QuoteI graduated college in 1982 and my first company gave me a relocation stipend of $2000. This was supposed to get me moved and settled in my new town, San Diego! I lived with my sister and moved my self so used that wad of cash to buy a killer stereo complete with a Nakamichi LX-3 Cassette deck. The bargain option of their line of amazing Cassette machines- it was $500 IIRC. Cassettes were a great format and were/are under appreciated. A year or two later, 1984?- CD's came out and Vinyl and everything else seem to disappear overnight. I think the cost of reproducing CD's in high volumes was peanuts compared to pressing LP's. These things go in cycles. 8 tracks fit the time pretty well. You could access any quarter of an album (10 minutes- 2 songs?) with a click. They crammed 4 stereo channels on a 1/4\" tape roughly the density of pushing 4 tracks onto 1/8\" cassettes but all that moving head stuff was pretty dodgy. I lived through all the audio formats and my favorite is probably CD's but for portability and convenience, MP-3 is a winner. (not an audiophile). I have 40G of music on my phone and spotify, its all just too easy."
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 20, 2025, 12:12:32 am",
"content": "Quotewouldn't say there hard to find,but maybe its different over here,5 minutes from my door i can pick up an entry level turntable for just over £100 in a shop thats more tv /home cinema biased than hifi,and one of our larger online sellers has 157 models to choose from.Ive still got all my vinyl going back to the first albums i was given, they still get played regularly and my trusty ole P3 still makes em sound good, crackles an all.QuoteI was a big fan of mini disc.First used them for sound fx playback,replacing a revox, life became so much easier,and soon realised what a good format it was,especially as work had free loan of cds at the local libaryQuoteThey never really took off over here,cassette was way more popular.pity nobody seems to do a reasonable priced machine that sounds decent these days but i guess theres no market for them."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 20, 2025, 10:57:51 pm",
"content": "It's The Sound, man....THE TUNES !As long as we are on the subject, of MP3 sound vs CD, (etc.) MY motivation is two-fold:First, I like bass, in balance of course, but bass response is a big part of concert-going excitement ! So a good Dual brand automobile low end speaker (10 inch), helps providing a moderately loud low end sound.Second, I have several music related projects, a standard scale 5 string bass, tuned down a fifth, and a toy based REVERB microphone.The microphone is also for picking up the bass guitar, hopefully with a heavy, mechanical spring reverb sound. For that I need a (sensitive) magnetic pickup.I'm also considering a piezo-audio pickup,...hence the interest in the record player (needle and piezo pickup).This cheapo TOY creates a non-electronic REVERB sound by using a focus sound cup, and with an attached spring, at the apex of the hard plastic cup. It's enough to create a large room or auditorium reverb sound, having a long delay (or persistence of the general sound frequencies that happened over the last couple of seconds).Plan is to try using one of my electric guitar pickups, to pick up the mechanical vibrations, of the internal spring."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 20, 2025, 11:04:23 pm",
"content": "Quote from: RJSV on July 20, 2025, 10:57:51 pmNow that sounds tres kewl.How does the toy pick up the reverb sound at the other end of the spring?Piezo pickup of some kind (my guess)? something else?Hell, that's how all those old Fender amps created that great reverb sound they had.Ever pick up an amp a inch or two off the floor and drop it? You can definitely hear the springs hitting their casing.(Not recommended to try with tube amps!)"
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 21, 2025, 12:01:57 am",
"content": "Well the toy microphone gathers sound through the usual grill and that collects into a hard plastic cup, similar to how we used to use a string, as kids, for communicating (yelling \"what ?\"), to the other kid's paper cup.Once that plastic cup vibrates, the spring connected to the end will transmit vibrations down the spring, and also up and down the length of the spring multiple times. A kid using this toy has to bend an ear against the end of the microphone, but then things sound like in a big cavern or auditorium."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 21, 2025, 12:16:12 am",
"content": "Quote from: RJSV on July 21, 2025, 12:01:57 amAha.So you'll need to add some kind of pickup at the end of the spring, plug it into some kind of amp.Sounds like fun."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 21, 2025, 12:32:25 am",
"content": "Yes as my standard guitar, at approx. 28 inch scale, is an acoustic Ovation brand, featuring an engineered plastic body, in back of the usual wood diaphragm style body top and sound hole.Usually, I understand, a piezo style pickup is located on the vibrating bridge. My plan, is to use a coil, or an existing guitar pickup for obtaining the microphone audio, along with audio reflections.Next after that, is attempting to make the reverb effect adjustable in the 'depth' or amount of special effects getting introduced as a 'color' to the real-time sound happening.Otherwise, a heavy reverb sound can get annoying, or inappropriate for the moment."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 21, 2025, 12:41:31 am",
"content": "Quote from: RJSV on July 21, 2025, 12:32:25 amYes, Ovations, as well as pickups (like Barcus-Berrys, etc.) use piezoelectric pickups. Very high impedance.QuoteDon't think a coil will work, unless you put it right next to the vibrating spring (which is steel).Try your guitar pickup here.QuoteMaybe just a simple high-R pot (250-500KΩ) in line with the pickup might work."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 21, 2025, 12:52:24 am",
"content": "No. It would have to be mechanical, like some sort of immobilizing screw turn. I would need to use, maybe a very short price of the spring, where the oscillating magnetic field gets picked up, whether by way of an 'official' guitar pickup, or just a simple but very high turns count solenoid coil.Problem would be how to isolate or dampen the excess spring, from introducing the delay and sound persistence.Ultimately might be better to simply add in a piezo sensor channel, for obtaining the 'dry' or non-effect sound.Besides...intention to experiment as a BASS guitar, usually played by single notes, isn't where most reverb effects are used. Just saying."
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 21, 2025, 01:02:51 am",
"content": "hows about a cheap small speaker,hook the end of the spring through the dust cap."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 21, 2025, 01:06:51 am",
"content": "Quote from: RJSV on July 21, 2025, 12:52:24 amOK. How 'bout some kind of damping material, foam rubber or such, that could be brought into variable contact w/part of the spring?"
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 21, 2025, 05:09:33 am",
"content": "The idea of small speaker resembles actual Fender Instruments transducer, which I now understand came from Hammond organ reverb development. Your idea (thanks, Thermahippy ) of using a speaker as a type of microphone is very close to the actual, TAPE HEAD style magnetically modulated sensor, that Hammond used.My idea will likely pick up all sorts of squeaks and scuffle sounds, as any microphone should, really. The Fender spring reverb uses all electronic input and so the only real worry is about doing the 'spring crash' sound, via extreme joustling of an amp, to cause physical contact of the sound conducting spring, with a side of container. That effect, BTW was used in an amusement park. In Knott's Berry Farm (L.A. area) there was a 'monster' gorilla used for creating very loud crashing and disaster noises. A person would walk up, and notice the little gorilla doll, bashing a set of SPRINGS with his little sledge hammer.The BASS or BARITONE guitar uses weed trimmer line, for the 5 strings tuned a fifth low;String #1: 'B', uses 0.065 inch line,String #2, 'G', using 0.065 \" as well.String #3, 'D', uses 0.080 inch lineas well as String #4, 'A'.and String #5, 'E' uses line at 0.095\" or about 1/10 inch. That thick line doesn't ring out so much, musically."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 21, 2025, 05:16:00 am",
"content": "That bass/baritone guitar sounds a lot like the Mexicanguitarrón, a pretty powerful instrument. Really booms out."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 21, 2025, 06:22:21 am",
"content": "Quote: \"Junk phonos\", (Pornographs). Since I am into word mangling sarcasm, I guess I would have to accept that reader's contribution. Besides, as many members here know, getting some possibly negative commentary does serve to get my own ideas moved, to the top of the heap...(Wistful Sigh...)BTW, doing the 5 string bass project helped me to learn better ways to do mechanical caliper measurements, for high accuracy in the new guitar string spacing. It turns out, that each string, on a 5-string, is spaced to 1.25 or 1 and 1/4 of the original, standard 6-string spacing.That forced me to focus, on getting the utmost accuracy, from my newly purchased calipers.There was enough space, to ignore the old slots, and create new slots for string placement, in the guitar nut. The guitar bridge will still need a bone or ivory material newly cut, for slots for string placement."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 21, 2025, 07:56:54 am",
"content": "Quote from: RJSV on July 21, 2025, 06:22:21 amBone. Nobody uses ivory anymore (except maybe a couple of African poachers).If you don't want to pay music-store prices for a bone blank (kinda expen$ive), get a bone from the butcher. You'll have to get the grease out of it, but it's the right stuff for a nut or bridge."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 21, 2025, 08:05:42 am",
"content": "Are YOU an AI ??YOU are, an AI, right ? (Who builtz yous ?)"
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 21, 2025, 08:09:40 am",
"content": "Last time I needed to change string placement, I used a stainless steel rod, which has plenty of hardness. The little rod fit into a small U-channel that also included string height adjustment, of the two rod ends."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 21, 2025, 08:40:48 am",
"content": "Quote from: RJSV on July 21, 2025, 08:05:42 amYes. I.am.an.AI.Take.me.to.your.leader."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2025, 08:59:54 pm",
"content": "Rick, an idea for your project:Instead of using a guitar pickup (which might work but seems unwieldy because of its shape and size), how about making your own pickup?Shouldn't be too hard: get yourself one of those \"super magnets\" (neodymium) in the shape of a small rod, wind a bunch of magnet wire around it. Put it close to the spring and connect it to your guitar amp.I'll bet that would work just fine. You'd need a few hundred turns of wire, I'm guessing."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 27, 2025, 11:33:15 pm",
"content": "Pickups have a LOT of turns, otherwise they might require a high gain preamp. But, the advantage I see, over, say, a piezo crystal pickup, is the piezo would essentially also pickup any rubbing or impact sounds, maybe even better than the musical tones.The whole, experimental rig is going to have that bulky TOY 'microphone' looking case INSIDE my Ovation brand acoustic guitar!Not very hard to work on, actually, as the standard size round sound hole allows a person to get 'one hand' inside. Note that I've also broken off the center brace, up under the deck (sound board front).BTW, it's a standard scale at 25 inches but I've altered the string spacing, for being a 5-string baritone. That actually was an enjoyable exercise, figuring and doing the new slot placements, (and purchasing a standard micrometer.Micrometer ? Sorry, I meant Calipers, which takes myself some memory recall effort. That's LYME DISEASE / CFS (chronic fatique' syndrome). I've had folks comment, over the years:\"YOU could have come up with a better name, for the disorder!\"Ahh, sorry, I guess.But one telltale distinction, is that the measuring and reasoning skills aren't so much impacted, while the memory and 'brain fog' aspects rage. I suppose perhaps. that disease / disorder puts a person into the whole, autism-like spectrum, for symptoms.At any rate, on the guitar string spacing change, I concentrated on accurate use of my calipers, to place 5 strings into the usual 6-string spacing. Turned out I needed to space them at 1 1/4 X the original.One (new) slot in the middle of the end 'nut', and 2 new slots, while still retaining the slots on the ends (1rst and 5th now, but was 1rst and 6th strings in the original guitar).That was, actually, more a satisfying job, than actually PLAYING the sucker is. (Go figure, huh).- - Rick B."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2025, 11:47:11 pm",
"content": "Wow. Does the guitar actually play in tune? That's definitely a non-trivial thing, re-scaling a guitar.I know; in a previous lifetime I was a guitar repairman. But I never did anything like that!Sure, refretted a few instruments, but that's easy by comparison; just put new frets in the old slots."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 27, 2025, 11:49:22 pm",
"content": "...but you are correct, as the best would be a bobbin (machine screw) having many, many turns, hand-wound. Big difficulty today is the simple lack of direct retail, as I've been buying my brass wire from various ARTISTS...No Radio-Shack. Although I believe Berkeley, CA still has the store: Quintronics, as in owner Mike Quinn!Best to wind the sensor with many turns, for better S/N ratio in the AMP (that's Signal to Noise ratio).Gonna put in a movie and wind, wind, wind."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2025, 11:56:11 pm",
"content": "Quote from: RJSV on July 27, 2025, 11:49:22 pmNope. Mike Quinn went out of business a loooooong time ago.QuoteYou might could make yourself some kind of winding jig to make it easier. Here's mine:The problem otherwise is that the thin magnet wire tends to get all tangled up, which is a total pain in the ass.Yeah, a machine screw, nut and 2 washers would make a pretty good bobbin. Cover the threads with tape first."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 28, 2025, 12:00:07 am",
"content": "Yeah, in tune, at a fifth below standard guitar pitch.Although the thickest / lowest 'string' is very dull, at 0.095 \" inches.I try to play: Third Stone from the Sun, partially, (as taught to myself by the late, Buzzy Linhart.). That chord sequence starts in after the intro and is a basic 'C' chord, but with the high C note dropped a half-note, by omitting that finger. Literally it's an 'F', but I'm talking in terms of standard 'C' chord SHAPE. That's a major 7th jazz style chord.(Sorry no photo). That break, BTW, happens twice during the long instrumental as Hendrix takes off into heavy blues licks for a few moments. Very nice and Jazzy derivative.They say he was good, on the guitar.... (Ahem)"
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 28, 2025, 01:45:53 am",
"content": "Aaaaargh. I totally misread your previous post, where you said you altered thestring spacing.I somehow brain-farted that to mean that you altered thefret spacing.Which would have been a hell of a job.But still, if you got the string spacing right, good for you.I've played tenor guitars (4 strings), never a baritone. I'd like to have a tenor again (had a Harmony a long time ago); great accompaniment axe."
},
{
"post_id": "",
"author": "RJSV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 28, 2025, 02:47:58 am",
"content": "No harm done. I declined to nit pik, (and others are so involved, in their own goals, that they often don't notice some flaw or typo error.Point was, I had purchased a MECHANICAL oriented device, as part of a way to force things, in the direction of my passion, which is the nano-scale Computer Architecture, melded with the existing electronics development.A couple of teaching toys have surfaced, using rolling ball activated logic. My approach went way, way complex, into whole systems.I mean: WHO wants 98% of a machine that needs FULL function.But, there are snags; a big obstacle is that a ball bearing poses substantial swallowing hazard! Especially for young school starting kids...a deal breaker, I've felt..."
}
] |
2025-10-17T16:15:51.488523
| 31
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(mystery-connector)-nitendo-ds-touch-screen/
|
[SOLVED] [Mystery connector] Nitendo DS touch screen - Page 1
|
[
{
"post_id": "",
"author": "nickn4",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 04, 2015, 02:10:05 am",
"content": "Hello everyone,A long time ago, i bought an little touchscreen for one of my projects but i never got to play with it because i don't know where to get a connector for this type of cable.the specific product i bought can be found here:DealExtreme - Nitendo DS touch screen €2.41When i started my Journey, i had no clue what search terms i could use to find the name/type of that specific cable+connector. after a couple of weeks i started getting somewhere,What i am looking for might be called theflat flex connector. but even now that i have a name i cant find an appropriate connector matching the 4-pin cable.i did however find that sparkfun has a breakout board for this Nintendo module, can be found here (picture 5):https://www.sparkfun.com/products/13631there might be a change that my particular cable has different dimensions, i can check on that if required.but first i really need to know what connector that is and where, for the love of god, can i get them.PS:open attachment if you don't want to open linkthanks allot for your timenick"
},
{
"post_id": "",
"author": "nickn4",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 04, 2015, 02:14:39 am",
"content": "offtopic:lol just found out i write allot instead of \"a lot\". im so bad at language stuff please excuse me. not gonna bother editnick"
},
{
"post_id": "",
"author": "john_p_wi",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "June 04, 2015, 02:47:44 am",
"content": "Look for zif connectors. You'll need to know the width, pitch (spacing of the flat flex contacts), number of contacts and determine if you need top or bottom contacts."
},
{
"post_id": "",
"author": "nickn4",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 04, 2015, 03:00:02 am",
"content": "Ok i will look it up tommorow, will measure everything, scout for some zif connectors. will keep you updated for the people who are interested too.nick"
},
{
"post_id": "",
"author": "kolonelkadat",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "June 04, 2015, 04:14:03 am",
"content": "so just a 4 pin ffc connector? or am I missing something?http://www.digikey.com/product-search/en?pv88=6&FV=fff40016%2Cfff80421&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25"
},
{
"post_id": "",
"author": "nickn4",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 04, 2015, 09:00:56 pm",
"content": "okay i have been looking around, have not found an exact match yet but will keep you informed.@kolonelkadati will check on that link as soon as i come back home in about half an hour.also here are my dimensions i measured. there might be a slight error because my caliper is not top notch quality.see attachment."
},
{
"post_id": "",
"author": "john_p_wi",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "June 04, 2015, 09:19:43 pm",
"content": "Look at pages F8 and F9 for info, click on the \"4 circuits\" for data sheet...http://www.molex.com/catalog/web_catalog/pdfs/F.pdf"
},
{
"post_id": "",
"author": "nickn4",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 04, 2015, 09:39:09 pm",
"content": "Okay, i needpart no 52745-0497, but now i need a distributer that ships to holland for a reasonable price (product only half a euro, dont want to pay ten times over for shipment) with a mininum order amount of 1. how do i go about that?i checked on some of molex's distributer's but the order amount is min 1000 or 5000.i also checked on digikey but it seems they ask 30$ for shipment if product price is under 100$ so i wont try that lol..any idea's?"
},
{
"post_id": "",
"author": "jwm_",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 04, 2015, 09:46:02 pm",
"content": "Quote from: nickn4 on June 04, 2015, 09:39:09 pmYou can get free samples from molex themselves usually if you just want a couple.Joh"
},
{
"post_id": "",
"author": "nickn4",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 04, 2015, 10:11:13 pm",
"content": "I have no company, what should i fill in the required forms \"Requester Company Name\" and \"Industry\" and \"Job Function\" and \"Ship To Company\"?and how much will shipment cost, i have to enter a FedEx, or UPS account that will be charchednick"
},
{
"post_id": "",
"author": "Jorpy",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "June 04, 2015, 10:20:21 pm",
"content": "Quote from: nickn4 on June 04, 2015, 09:39:09 pmTME has itShipping should be about 10$Minimum order amount is 2 though.."
},
{
"post_id": "",
"author": "nickn4",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 05, 2015, 02:20:06 am",
"content": "@JorpyThanks i ordered 2 of themI could not have done this without you guys! the names for these connectors are hard to trace for me when i had no clue, but things start to make senseEveryone who helped me, THANKS A LOT!nick"
}
] |
2025-10-17T19:39:24.274604
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(need-help)-atx-power-supply-ocpuvp-disabling/
|
[Need help] ATX Power Supply OCP/UVP disabling - Page 1
|
[
{
"post_id": "",
"author": "ipullstuffapart",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 19, 2014, 05:37:38 am",
"content": "Hi guys! I'm new to the forum here, but am indeed a fellow Eevblog viewerHoping you could help me out with a bit of a pickle I'm having with a project of mine.I am attempting to run a car amplifier off of an ATX power supply.As a note : Yes the power supply is capable of running the ampSo as I've found, trying to turn the amplifier on causes a rather horrific undervoltage lockout on the PSU as the amp turns on. This is a huge problem.I have read on the RepRap forums that people have been able to disable the undervoltage protection on their power supplies to stop them from... well, turning off under load when used for 3D printing. This person was using an EST. 7502C (datasheet) and disabled it by shorting pin 4 to ground and breaking the trace to pin 4 on the board.I have checked on my PSU and it is running a CP494 (datasheet), however as my knowledge of EE is hazy at best, I was wondering if I could get a bit of helpful advice on how to disable the UVP on my supply as I can't get my amp to run.Thanks!Sean"
},
{
"post_id": "",
"author": "Whales",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 19, 2014, 07:18:58 am",
"content": "QuoteBy what margin? Keep in mind many PSU manufacturers hideously overstate the ratings of the PSU. Even honest labels are arbitrary to some degree: some manufacturers give a stable max with a small amount of headroom, others give a theoretical max (where the unit starts screaming for its life).I'm only vaguely familiar with the topology of audio amplifiers, so I assume the inrush current to charge its primary capacitors is what's triggering your OCP. Perhaps looking atinrush current limitingmay be of help. Mind you, if the PSU can't survive the capacitor charging, I severely doubt it will be able to supply enough power for the amp's max output -- YMMV, and new PSUs arerelativelycheap."
},
{
"post_id": "",
"author": "ipullstuffapart",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 19, 2014, 12:57:19 pm",
"content": "Quote from: Whales on March 19, 2014, 07:18:58 amSpecifically speaking, there is very little headroom, the amp pretty much peaks what the power supply can handle (and it is a cheap supply so most likely overrated output).> What doesn't help is that the amp, though rated as a 300w monoblock by Rockford Fosgate actually puts out just over 400w at 5%THD, so with head loss and everything accounted for, we're looking at about 35+ amps at 12vHowever, it is not as if I will be having this amp screaming as it is going to be powering a sub for my computer, meaning for any decent SQ with my speakers, it'll be running at about 1/5th capacity, it's just the sudden charge load when it's turned on that gives it a peak to trip it.To be honest however, I just want to do a workaround for the supply, as car amps can handle massive voltage changes when they create a bit of load (eg when it turns on, I'm not too worried about a stupid 1% or so drop in voltage that the UVP is tripping for, and if the power supply blows it's not a huge issue for me (I have about 10 of them ripped from a bunch of ex-govt computers) so replacement is easy."
},
{
"post_id": "",
"author": "Kjelt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 19, 2014, 01:10:31 pm",
"content": "You have to look at the buildup of your powersupply, if the 12V is a single rail or multi rail. For instance if the PS is 300W rated that usually does not mean it can deliver 12V and 25Amps but for instance 2 times 12V 10 amps and the rest in 3,3V and 5Volts.Then next step is to startup the PS with a small load and after it has start up add the caramp with a resistor in series to limit the current to 10Amps or so, if that all works bypass the resistor and play the music see if it still holds out. That should give enough information where it goes wrong."
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 19, 2014, 01:28:46 pm",
"content": "Well, you can limit the inrush current wit a lightbulb. If you can find a big enough one..."
},
{
"post_id": "",
"author": "ipullstuffapart",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 19, 2014, 03:19:56 pm",
"content": "The PSU is indeed a single 12 volt rail, so no real worries there. I did try it with a few hard drives and DVD drives plugged into it and started the amp, same result. I guess a long read of the data sheets may uncover how to disable the UVP.... The idea is to have a $0 budget"
}
] |
2025-10-17T20:05:54.676443
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(newbie)-servo-capacitor-filtering-question/
|
Servo capacitor filtering question. - Page 1
|
[
{
"post_id": "",
"author": "Pedro R.",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 21, 2016, 12:41:27 pm",
"content": "I am designing a PCB for a hexapod robot with 19 servos(3 for each leg, 1 for a ultrasonic sensor positioning), controlled by an Arduino Mega and it kind has some jitter to it, and I wish to use some capacitors in it so it can have less external noise. I was wondering if there is a quick answer for the following question. Where should I put the capacitor with which value? I've seen EEVBlog recent video about bypass capacitors but I'm not really sure how to get ESR and ESL values so I can calculate the resonance frequency and all that stuff, and I think there is probably a rule of thumb for that, my guess, that I've made from previous research is, just put a 10nF ceramic capacitor between VCC and GND. My doubt is, for a servo, is it better to put the capacitor to VCC or SIGNAL? Also, is 10nF an appropriate value? Also, I'm using a 7.4V LiPo battery to supply, and I drop this voltage to 6V with some diodes, and have 10k pull up resistors in the signal pin (I know diodes are not the best way to regulate, but I'm from Brazil, and we don't actually have many parts available here, so It's kind hard to find regulators others than LM317 or 78XX that needs 2V drop, which we don't have in this case, and everything from the internet takes 1 mouth+ to arrive and have salty shipment fee).So resuming my questions.Should I put capacitors between VCC and GND, or SIGNAL and GND?Should I use 10nF as a rule of thumb, or there is better method?If someone can explain me the decision making process on this situation I would be really happy. I appreciate your time trying to helping me, sorry if I said anything wrong or misspelled anything, English isn't my first language, tell me if I've got anything wrong. Already, Have a good day! O0"
},
{
"post_id": "",
"author": "retrolefty",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 21, 2016, 02:29:42 pm",
"content": "Servo jitter as a symptom could have a number of root causes each of which should be considered:Insignificant current/voltage source for driving the number of servos that may have variable mechanical load(s) and always variable current requirements between moving, stalled, or at position. This is best seen with an o-scope and cannot be fixed with bypass filtering.Firmware/software problem(s). Only posting actual code can anyone other then yourself look it over.Bypassing between signal and ground is almost never the correct electrical fix for a jitter problem."
},
{
"post_id": "",
"author": "Kilrah",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 21, 2016, 06:35:22 pm",
"content": "Given the signal to a servo is the width of a square pulse, putting a cap on that would basically destroy the one important characteristic of that signal.But your problem is very likely firmware, cleanly driving 18 servos from a Mega sounds impossible without clever tricks and external hardware. You can't really drive multiple servos without jitter with a software-only solution on a processor of that speed, and there aren't 18 hardware PWM outputs on a 2560."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 21, 2016, 08:44:29 pm",
"content": "100uF 10V low ESR electrolytics between +5V and 0V right at each servo can be very helpful if the servos have long wires to them. Use a switching regulator for the servos (e.g. a DC-DC buck converter module off EBAY if you cant get anything better easily) and a 5V LDO regulator for the Arduino Mega (as the on-board regulator needs too much headroom for operation down to 6V), and powering the MCU from the noisy servo power rail is asking for trouble.Its possible to drive up to eight Futaba compatible servos from one hardware PWM channel (capable of arbitrary pulse generation), by using a 74HC238 demultiplexer to steer the generated pulse (applied to its E pin) to each servo in turn, and in an ISR, while the pulse is low, changing its address pins to select the next servo, + updating the pulse width. The result is interrupt driven background jitter-free servo control with all edge timings handled in hardware. To do this successfully you'll have to throw out the Arduino servo library and write directly to the ATMega registers."
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 21, 2016, 10:43:55 pm",
"content": "The best bulk caps are Polymer Tantalums.https://www.newark.com/pdfs/techarticles/kemet/Replacing-MnO2-with-Conductive-Polymer-in-Tantalum-Capacitors.pdfRegards, Dana."
},
{
"post_id": "",
"author": "Pedro R.",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 23, 2016, 12:39:18 am",
"content": "Thanks a lot for all the good people who wrote useful information, the aggregate of all will certainly help me with my decision process. If anyone wants help out with more information, I would be pleased if you did. Again, thanks a lot people."
}
] |
2025-10-17T19:21:53.771588
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(noob)-choosing-a-potentiometer-for-a-12v-fan/
|
[NOOB] Choosing a potentiometer for a 12v fan - Page 1
|
[
{
"post_id": "",
"author": "TDA81",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 12, 2021, 06:47:21 pm",
"content": "Hi, guys!I want to wire a 12v server fan directly to the power supply, inside a pc.I can't wire it directly to the motherboard due to it's power consumption (4.3W), and I want to use a potenciometer so I can control the fan speed.The specs of the potentiometer is what I need help about.I did my math (that is probably wrong) and the results are far, far away of the specs of the pots I find.The fan is:PAPST MULTIFAN 4212/2 G12v - DC 4.3w(7-14.5v DC)By my calculations (that might be wrong!!), I need a pot with about 40 ohm and rated for 1.5w (1.07w plus safety margin).But all I can find are pots with 1k, 10k, 50k... and really low power dissipation. Hence, I believe my calculations are wrong, and I deeply need your help.What potentiometer should I get for my fan??Thanks in advance.T. AtalaiaPS: Sorry for my bad english..."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 12, 2021, 07:28:12 pm",
"content": "Very 1960s and expensive solution. You need a wire wound power pot for this.Better solutions:1: LM1117-ADJ set for 7...12 V output.2: PWM control. I'm sure highly qualified experts will supply any number of 555 solutions."
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 12, 2021, 07:47:42 pm",
"content": "Quote50 ohm 5 watt pots are fairly common,for examplehttps://uk.rs-online.com/web/p/potentiometers/1790672/"
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 12, 2021, 09:20:54 pm",
"content": "Quote from: themadhippy on March 12, 2021, 07:47:42 pmYes... at £3.10. Not really a bargain, and a lousy solution on top. The fan is not a simple brushed DC motor. It's a BLDC with integrated controller that stops working under 7 V."
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 12, 2021, 09:34:14 pm",
"content": "Did i say it was a good or bad solution?No, however i did show the o/p were to find something close to what he was asking for."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 13, 2021, 10:23:06 am",
"content": "For a resistor solution, I would go for a fixed resistor and a switch to bypass it, giving you two speeds. If you want more control, then you could use two resistors and a centre-off toggle switch to bypass one or both, giving you three speeds. Going beyond that is probably a bit anal.Using a couple of 2W resistors an toggle switch is probably the cheapest too, and avoids worries about the fan not starting if switched on with the pot turned too low.The LM317 solution would probably be the cheapest for fully variable control, as long as you restrict the minimum output voltage."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 13, 2021, 07:34:45 pm",
"content": "Quote from: Gyro on March 13, 2021, 10:23:06 amI mentioned LM1117 on purpose. The LM317 has far too much voltage drop."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 13, 2021, 07:42:26 pm",
"content": "Good point."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 13, 2021, 10:21:35 pm",
"content": "Just use an emitter follower with the potentiometer and resistor on the base and fan on the emitter."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 13, 2021, 10:47:50 pm",
"content": "Quote from: Zero999 on March 13, 2021, 10:21:35 pmAlso an idea, but I think you need to refine it a bit. Otherwise the B-E junction will pass all the current at full speed. To avoid this, you're into the same voltage drop as the LM1117."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2021, 05:05:54 am",
"content": "A variable resistor of that power handling capability is usually referred to as a rheostat. As others have mentioned, more efficient solutions are available, and in this case you may want to use a MOSFET connected to the PWM output from the motherboard which will let you vary the speed but not overload it."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2021, 08:45:19 am",
"content": "The easiest solution is to use a linear regulator with a low voltage drop and use a regular potentiometer to adjust the output voltage. 1117 has low voltage drop but there are regulators with even lower voltage drop.If you don't need super fine control and you'd be fine with just a few steps , then you could use a slide switch (or a sort of rotary control/switch) to switch between different resistors or different number of diodes.For example, see picture below ... by moving the slider, you short out a different number of diodes (remove them from circuit basically), so the voltage drop across changes. On the first position, there's no diode shorted, so you get n diodes x voltage drop per diode at that current ... one position to the right will short one diode, next position will short out two diodes and so on..with 1n5817...1n5719 and your fan that consumes around 0.35a, each diode should drop around 0.6v ... if you use 1n400x you should get 0.8v..1v drop.If you go with resistors, you can calculate your fan's internal resistance using this page :https://www.blackfiveservices.co.uk/fanspeedcalc.phpand then pick resistors to limit current at various levels.For example you say 12v 4.3w or 0.35A ... like the page shows you have V = IxR so your fan resistance is 12v / 0.35 = ~ 34 ohmIf you want maximum current, you set a 0 ohm resistor or just connect wires directly like the first position for the diode layout in the picture belowIf you want let's say 7.5v, then the resistor will have to be aroundtarget current for 7.5v V = IxR => I = 7.5 / 34 = 0.22Avoltage drop across resistor 12v - 7.5v = 4.5vSo again V = I x R ... 4.5v = 0.22A x R ... R = 4.5/0.22 = 20.45 ohm so a standard 21 ohm will do ....Power dissipated over the resistor would be 4.5v x 0.22a = 0.99w , so you'd want to use a 2-3w rated resistor or two 10 ohm resistors in series (for a total of 20 ohm) so that each resistor generates 0.5w of heat, making it possible to use 1w rated resistors."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 14, 2021, 09:48:31 am",
"content": "Quote from: Benta on March 13, 2021, 10:47:50 pmWhat makes you think that? The base will only pass too much current, if VBis taken above VC, which will only happen if there's a lot of resistance in Q1's collector, compared to R2, otherwise IB= IC/hFE."
},
{
"post_id": "",
"author": "bobbydazzler",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 14, 2021, 04:26:38 pm",
"content": "I thought most motherboard fan headers could supply up to 1A current? Have you tried plugin it directly into the motherboard yet? Otherwise I think a simple lm317+trimpot regulator or make 3 different speed settings with resistors is easiest."
},
{
"post_id": "",
"author": "archil",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "March 16, 2021, 08:33:58 am",
"content": "right way!"
},
{
"post_id": "",
"author": "perieanuo",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 16, 2021, 02:03:39 pm",
"content": "here you go, with automatic temperature control, you set the temp that starts the ventilatorI use that in some ps I designed"
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 16, 2021, 02:32:39 pm",
"content": "Quote from: perieanuo on March 16, 2021, 02:03:39 pmShould work, unless the OP needs the tacho output. I that case it should be inverted to a P-channel circuit."
},
{
"post_id": "",
"author": "LooseJunkHater",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 17, 2021, 06:27:56 pm",
"content": "Hey op, if this is a server fan, consider using a PWM + duty cycle signal to control the speed of the fan, instead of controlling the voltage; most desktop/server fans don't respond to voltage changes for adjusting the fan speed.A stupid-cheap option for controlling the PWM + duty cycle would be the SG3525 module from eBay. These can be found for about $1.5USD.To control the fan, set the modules PWM to 25khz, and vary the duty-cycle between 0-100%.If you need more assistance, let me know!"
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 17, 2021, 06:46:29 pm",
"content": "Quote from: LooseJunkHater on March 17, 2021, 06:27:56 pmThis is three wire fan, 25 kHz would never work (that's for 4-wire fans). 50 ... 100 Hz is OK.Three wire fans only have power input plus tacho output, so you'll need to PWM the supply voltage. Four wire fans have a separate PWM input, which is specified for 25 kHz."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 17, 2021, 06:47:49 pm",
"content": "You can buy little devices specifically intended to control the speed of computer fans. They are a little box that plugs inline and has a pot on it, internally I'm sure they're a simple PWM driver."
},
{
"post_id": "",
"author": "LooseJunkHater",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 17, 2021, 07:12:07 pm",
"content": "Quote from: Benta on March 17, 2021, 06:46:29 pmI'd be very surprised if their server fan is 3-wire (12v, gnd, tacho), as 90% of the ones I've come across are 4-pin. Also, where was it mentioned that it's a 3-pin fan? I must have missed that part."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 17, 2021, 07:55:34 pm",
"content": "Quote from: LooseJunkHater on March 17, 2021, 07:12:07 pmThe OP lists the fan part number IN THE VERY FIRST POST, and it's a three wire fan. OK?"
},
{
"post_id": "",
"author": "LooseJunkHater",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 17, 2021, 08:33:55 pm",
"content": "Quote from: Benta on March 17, 2021, 07:55:34 pmWoops, you are 100% right. Sorry, I had a feeling I missed something :p"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 17, 2021, 09:02:40 pm",
"content": "I'm sure you can find something cheaper but I've used things like this a few times.https://www.ebay.com/itm/Gelid-Solutions-Fan-Speed-Controller-with-Manual-RPM-Control-3pin-Case-Fans-0-7A/233927307056"
}
] |
2025-10-17T17:31:34.489113
| 24
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(noob-mistakes)-importance-of-op-amp-decoupling/
|
[noob mistakes] importance of op amp decoupling - Page 1
|
[
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "June 09, 2017, 09:00:31 pm",
"content": "Hey guys, I had an almost detective story today. I was experimenting charachterizing different opamps I have.Essentially, I measure offset voltage (Vos), input current and Vos change with temperature (I use a heatgun set at ~100C, cheap thermocouple shows peak temperature at around 118C).I recently bought a bunch of NE5532D from TI because it was cheap, and one expensive NE5532D from ON SEMI.And I couldn't believe my eyes, the on semi's device was total crap all around.I kept staring at both chips until I realized there was something wrong... Got it, I soldered decoupling cap to wrong pins. Damn!So, once I fixed the cap all went good.The final stats: TI showed offset 0.05mV and 0.1mV (both showed 0.19mV at ~100C) if you trust uni-t 61. ON SEMI showed 0.43mV and 0.51mV (0.15mV and 0.51mV at ~100-110C). I tested only one sample of each, so results are not statistically significant and no conclusions to draw. Both chips are well within spec for the parameters I measured. But I would prefer TI chip for DC stuff. Anyway, I have two more chips from TI, will see how they perform.Now question.Do you think voltage offset will be better if I remove flux?I'm yet to try, didn't have spirit at hand.PS Just realized that chips only specified to work up to 70C. Huh, I wanted to buy SE5532 that has extended range, but it was not on sale on tme.eu ."
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 09, 2017, 09:59:37 pm",
"content": "Possibly the flux could increase bias current which in turn wouldgenerate offset from the source impedance.http://www.ti.com/lit/an/slyt166/slyt166.pdfRegards, Dana."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 09, 2017, 11:20:53 pm",
"content": "The 5532 has a high input bias current anyway so it would take a lot of leakage to become a problem. In audio applications there is an assumption that AC coupling at some point will remove DC errors so bias current and leakage are of secondary importance.Low bias current is used where high impedance is needed to keep capacitor values reasonable. In low cost applications, FET input operational amplifiers are used not for their low input bias current although this does make design easier but because of their AC performance advantage from lower input stage transconductance. (1) Some people think they sound better but I am dubious.(1) Do a search for transconductance or Gm reduction in operational amplifiers.Thisis a good place to start and it is interesting to study how the 5532 achieved its AC performance."
},
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "June 10, 2017, 06:12:17 pm",
"content": "Thank you very much for the link.I cleaned the flux but, unfortunately, I confused wires and applied to the inputs 5 volts below the ground. The result -- no real changes in offset voltage (it become slightly worse, but after thermal cycle it become slightly better, so, I guess, mechanical stress?). But the input current now just like a wild between 2 and 4uA. I think I blowed the input diodes (even though my PSU was set to source only a few mA a current, but it has 10uF output cap, so peak discharge current is high).So I took another TI opamp and... it has Vos 1.26mV and 0.68mV (still within spec). Way much worse than the previous sample from TI. Damn, I destroyed my best opampOne thing surprised me is that thermal cycle may change Vos after cool down. On the picture below you can see I managed to get zero offset (according to my uni-t 61, opamp connected in unity gain configuration, supply voltage 17.5V unipolar, input voltage 5V). Although I'm not sure if this is a permanent state."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 11, 2017, 07:30:55 am",
"content": "It can be a tricky to measure the input offset voltage and bias current directly from the input terminals; the capacitance of a long lead at the inverting input can cause oscillation or RF can get in and be rectified.Usually offset and bias current are measured at the output in a configuration where the operational amplifier amplifies its own offset by 100, 1000, or any convenient fixed amount. Bias current is measured by adding a known resistance in series with one input at a time and measuring the change in offset."
},
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "June 11, 2017, 08:41:33 am",
"content": "Thank you very much for suggestion with the resistor. I actually only measured input current only at positive input (the sum of both inputs, I connected positive inputs together). So, perhaps, it's time to repeat measurements again, but in a proper way.I used unity-gain configuration because I don't have precision resistors. But now I think I may want to try it. I will not get accurate numbers, but I can compare opamps between themselves (provided I use the same resistors)."
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 11, 2017, 08:43:28 am",
"content": "One approach to measurement -http://www.analog.com/en/analog-dialogue/articles/simple-op-amp-measurements.htmlRegards, Dana."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 13, 2017, 08:43:05 am",
"content": "In an op-amp with a BJT input stage, the bias current has a negative temperature coefficient. As the temperature is increased, the Hfe of the input transistors also increases, so they sip less base current in order to maintain the same collector current, which is normally fixed by a current source/sink inside the op-amp.Whilst it's very good to understand this, you shouldn't lose sight of the fact that the NE5532 was never designed to be a precision op-amp. It was primarily designed for used in audio amplifiers where the DC component is removed with AC coupling capacitors. Offsets due to the bias currents can also be minimised by making sure both inputs see the same impedance, with respect to 0V."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 13, 2017, 12:13:14 pm",
"content": "That is called bias current compensation and operational amplifiers intended for audio applications rarely include this feature for the reason you identify, AC coupling makes DC errors irrelevant, and because the bias current compensation both increases noise and usually increases distortion.There are ways to implement bias current compensation externally if necessary."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 13, 2017, 03:47:55 pm",
"content": "Quote from: David Hess on June 13, 2017, 12:13:14 pmI think you've misunderstood. I made no reference at all to bias current compensation. I just stated that: for BJT amplifiers the bias currents have an NTC, how to mitigate them and briefly explained why."
}
] |
2025-10-17T18:54:34.333873
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(opamp)-is-a-dual-rail-supply-required-for/
|
(opamp) Is a dual rail supply required for ... - Page 1
|
[
{
"post_id": "",
"author": "Audiofanman",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 04, 2025, 04:31:43 pm",
"content": "First... I'm a total beginner, learning what I can absorb every day..I could say EE is a 2nd language that I am picking up slowly lol...So I'm (still) developing a high impedance circuit (10Meg min) that reduces a negative voltage from -100vdc to -10, and using a unity gain inverting opamp drives an analog 1mA full deflection meter by using a resistive divider network.The expected range of function is really -6 to -3v, and conversely the output +3v to +6v dc. 10 just was a nice number giving me a bit of leeway.Does an opamp require a negative power supply for the inverting input to work well as some sort of internal reference with the inverting inputoris the negative power supply used most times so the opamp can work well under the 1v or so threshold (i forget the correct term, is it common mode?)I know that it depends is a valid answer applicable to any question with more than one answer lol so I found with ltspice and I ln real life, my non inverting op amp buffer works fantastic with no negative voltage source, but my ltspice sim is getting real complex as the ac power source i want to use is not center tapped and trying to float the output of a bridge in ltspice gives strange results, adding a virtual ground to the bridge with (2) 10k resistors to ground appears to solve most of the trouble i see.Got me thinking that 1, the negative rail model I have is more an ltspice issue and in real life floating the dc output from a bridge shouldn't be a problem..Or2, (probably more true) i know only enough to make myself feel more stupid hahaha.."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 04, 2025, 04:53:42 pm",
"content": "An inverting amplifier normally*acts to keep the inverting input of the OPAMP very very very close to the same voltage as its non-inverting input, which will be grounded if you don't want to introduce an offset. For single supply operation, you therefore need an OPAMP with common mode input range including its negative supply (and preferably min. 0.3V below that). If there is any risk the negative input voltage will be present with the OPAMP unpowered, you may need a clamping diode from -in to ground to prevent the pin being dragged very far negative.* It fails to do so if its output rails.Edit: I forgot to mention that a single supply OPAMP's negative supply *IS* ground! David's comments below are well worth your attention"
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 04, 2025, 06:20:25 pm",
"content": "Quote from: Audiofanman on June 04, 2025, 04:31:43 pmNo, the negative supply limits the negative side of the input common mode range, and the negative side of the output voltage range. For an inverting amplifier, the voltage across the input resistor cannot go negative because feedback will hold the inverting input to the same voltage as the non-inverting input, which will typically be ground (common).Difference amplifiers are sometimes made from a pair of inverting amplifiers to allow input voltages beyond the supply rails.QuoteThere are many reasons to include a negative supply."
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 05, 2025, 07:59:14 am",
"content": "With a single supply OP-amp (like LM358) one could get away without a negative supply. The input can work all the way to ground (= neg supply of the OP-amp) and a tiny bit (like 0.1 V) below. It depends on the OP-amp type (the parameter is the input common mode votage range) how for this works, e.g. the classic µA741 would not.One would not need a divider first. So it could be directly some 10 M from the input to the inverting input of the amplifier and than the FB resistor to get an inverting amplifier with a gain of maybe -1/10 or even less. So -100 V are converted to +10 V.The input is virtual ground and the amplifier does not see the high input voltage, as long as the amplifier can provide the compensating current. Unless already part of the OP-amp one wants the already mentioned clamping diode in case the OP-amp power is off, but the input voltage is on.If the meter movement is in series with the feedback path (one of the sensible configurations) one wants a parallel capacitor, as the inductance of the movement can add phase shifts and might cause oscillation."
}
] |
2025-10-17T16:17:52.918728
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(pcb-review-request)-pi-zero-breakout-for-sensors-3-30v-regulated-input/
|
[PCB review request] Pi zero breakout for sensors + 3-30V regulated input - Page 1
|
[
{
"post_id": "",
"author": "mrburns",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 15, 2023, 02:50:27 pm",
"content": "Hi, I could use some help with my hobby PCB design. There must be tons of rookie mistakes and other things to improve. This board is for Raspberry Pi Zero W and acts as a breakout for sensor modules. Mainly DHT22:s. The power will be delivered from battery or usb. I used Altium Circuitmaker2 for this project.▶ I used TIs online power designer to get the power delivery circuit I wanted. This one uses TI TPS55289 buck-boost regulator and takes 3-30 VIN and outputs 5V 500mA max. (avg usage will be 150-250mA). After the regulator the 5V goes to the PIs 5V pin and to the LM1117MP-3.3 linear regulator to feed the 3.3V to the sensors. I did not want to use the PIs 3.3v for possibly 20 sensors.▶ The GND is poured to the top and bottom and I already added lots of vias. Im little unsure of are the vias 'correct' size. I think I will order the PCBs from pcbway.com with SMD components assembled. pcbway website says that they require annular ring size of 6mil. They also state that all vias should be same size on the pcb. my Vias are 18mil diameter and 12mil hole size. Should I use smaller hole size? If the hole size is 6mil and the diameter is 18mil then the annular ring is 6mil right? There was no way to check the annular ring or add design rule on circuitmaker2.▶ The TPS55289 regulator has vias on its traces on the reference designs for heat dissipation and better grounding so the 18mil diameter was the largest I could fit in the design.▶ The reference design of the TPS55289 also showed and stated that there should be some separation between the AGND and PGND so I think I managed to copy the idea of the reference design.▶ The voltage to the sensors is selectable between 3.3V and 5V with jumper. I think this design of mine should also bee looked at. The ouput of the LM1117 regulator is disconnected from the sensor voltage line by NPN transistor if the 5V is selected to protect the regulator. Is this even necessary? I did not use diode because I did not want any voltage drop.▶ I have no idea if the mounting holes are correct and if there is some standard to them.▶ I will order the PCB with all SMD components assembled.SincerelyNot electrical engineer. (actually automation engineer) (▀̿Ĺ̯▀̿ ̿)Link to the project on altium365: ↓https://365.altium.com/files/F83B14F7-4F95-4AAD-81B0-549B5C326031Link to all files:↓https://1drv.ms/f/s!AnfIOtcTpP6BgrIedCTnukogk8Dn7w?e=TQX36dLink to TPS55289 pdf:↓https://www.ti.com/lit/ds/symlink/tps55289.pdf?ts=1689073822212&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS55289"
},
{
"post_id": "",
"author": "dobsonr741",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 15, 2023, 04:18:43 pm",
"content": "Gut reaction: the TPS55289 is an overkill. Also: are you OK soldering it?"
},
{
"post_id": "",
"author": "mrburns",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 15, 2023, 04:30:50 pm",
"content": "I will order the PCB with all SMD components assembled.I also like the versatility of the TPS55289. If I someday need to modify the design for 24V-out it should be quite simple.The I²C interface on the chip is also one thing Im looking forward to test out and play with."
},
{
"post_id": "",
"author": "dobsonr741",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 15, 2023, 07:29:18 pm",
"content": "It seems the I2C is the only way to configure the output voltage. How are you going to set it to 5V to boot the raspi up?"
},
{
"post_id": "",
"author": "mrburns",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 15, 2023, 08:47:53 pm",
"content": "Good point. I was under impression that using the TI power designer with 3-30VIN and 5VOUT 0.5A would give a schematic that would give 5VOUT by default but now Im not sure abouth that. In the schematic the VCC of the regulator is connected to EXTVCC so it gives 5V reference? If needed I can use any of my RPIs to set the registers to output 5V through the I²C interface.If it is the case that the registers are volatile and the ouput would need to be set every time it boots up then this would be a problem and I need to change the chip."
},
{
"post_id": "",
"author": "liaifat85",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 17, 2023, 11:23:03 am",
"content": "The vias you've used (18mil diameter, 12mil hole size) are generally suitable for most PCB manufacturing processes. However, since you plan to order from pcbway.com, and they require an annular ring size of 6mil, you should adjust your via hole size accordingly. To achieve a 6mil annular ring with an 18mil via diameter, you would need a hole size of 6mil. So, you can change the hole size to 6mil while keeping the diameter at 18mil. Having consistent via sizes throughout the PCB is good practice and helps with manufacturing.There are other designs at PCBway website faetureing Raspberry Pi zero like this:https://www.pcbway.com/project/shareproject/PiPod___Raspberry_pi_Zero_portable_music_player.htmlIf you have any dilemma, you can see these designs or ask their customer service engineers by mail."
}
] |
2025-10-17T16:51:14.419447
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(please)-help-me-pick-a-new-sig-gen/
|
(Please) Help me pick a new Sig Gen - Page 1
|
[
{
"post_id": "",
"author": "adamboon",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 20, 2016, 08:06:47 am",
"content": "Right. So We do mostly audio - I Already have a HP oscillator, that is super low distortion, 600? output and has a stepped attenuator - and I love it!I do, however, want something to drive a square wave into audio circuits - to establish ringing/overshoot - I've also found it a quick way to determine how something's Frequency Response is tracking through a circuit.I'm favouring this one:http://www.ebay.com.au/itm/162103238915?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITbut I've also looked at:http://www.ebay.com.au/itm/401071567565?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIThttp://www.ebay.com.au/itm/201590002731?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIThttp://www.ebay.com.au/itm/271274673004?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITI've watched a few HP Agilent 33120A see for more than I'm prepared to pay (I do like the look of them).I know a lot of people have the Hantek DDS 3X25, and there is one available for A$155 locally - which is good value - but I read it's a DA that spits out 7v max and then bit crushes below that - plus I don't love the idea of needing a computer to control it (although I always have a computer around... but it's usually a mac).I am concerned about the long-term reliability of the RAG101 - I'd appreciate any advise from owners of this one.Thoughts?Thanks.Adam"
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 20, 2016, 08:18:23 am",
"content": "What's your budget?"
},
{
"post_id": "",
"author": "adamboon",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 20, 2016, 08:32:29 am",
"content": "Well really I just want to make a good square wave at (and around) audio frequencies. If I get a more robust or versatile tool for a bit more $, then great (but as you know, you can quite quickly start looking at tools that are way overkill and unnecessary). I was also originally looking at some Siglent AWG units.I'm probably comfortable spending between $100 - $300, but could go a bit higher if necessary."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2016, 08:53:41 am",
"content": "On the other hand, if it's specifically square waves you need for audio testing, then it's about the easiest signal to generate yourself.Why not just build something with logic an switched attenuator and an AC coupled output. If you want a large output swing then you could use 4000 series logic running at 15V. You could tailor the output to your specific needs and also battery power it to avoid hum loops.Edit: You'll probably get a rather cleaner (quieter) square wave than something being generated by a micro and a DAC too."
},
{
"post_id": "",
"author": "adamboon",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 20, 2016, 09:09:06 am",
"content": "Quote from: Gyro on June 20, 2016, 08:53:41 amI had thought about this. I was probably just being lazy..."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2016, 09:17:33 am",
"content": "QuoteHaha, well there I can't help you.It does come down to the cost and bench space of yet another expensive grey plastic box covered with displays, lights and encoders, versus something small, simple and dedicated that puts our (say) spot frequencies at 100Hz, 1kHz and 10kHz."
},
{
"post_id": "",
"author": "System Error Message",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 20, 2016, 09:45:10 am",
"content": "When i was searching for a scope it is suggested that you use 12bit DAC/ADC at least for audio."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2016, 10:11:12 am",
"content": "But for a square wave generator you only need 1 bit!"
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 20, 2016, 12:25:01 pm",
"content": "One one these dinky things will get you by for cheap:http://www.ebay.com.au/itm/10MHz-DDS-Function-Signal-Generator-Sine-Square-Wave-Sweep-Frequency-Meter-/121633684437"
},
{
"post_id": "",
"author": "System Error Message",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 20, 2016, 01:29:50 pm",
"content": "Relating to audio there are some interesting bits about frequency especially if you have adjusted it on your PC. High end soundcards will do 192Khz per channel so how many Mhz you need is to take that value * number of channels (excluding the .1 or .2). Than theres also bit depth. Im not so sure how the bit depth ties into bandwidth but it may be related. Essentially even a 10Mhz signal generator should be enough.Seeing as you're working with 600ohm this means high fidelity audio so its not wrong to assume you are working on high end DACs. Good luck with your work and show us your work too. I've had bad luck with cards that use creative chips as for some reason creative chips are unreliable even though the only creative component on the card is the card CPU (the creative chip). New creative cards seem to work fine though with their \"quad core\"."
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2016, 01:48:34 pm",
"content": "You may want to consider theOwon AG051F 5 MHz Single Channel Waveform Generatorfor $199. It's big brother the Owon AG1012F was reviewhere.Saelig also has a discount for EEVblog members."
},
{
"post_id": "",
"author": "luxfx",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "June 20, 2016, 03:07:12 pm",
"content": "I just went through this, and JUST bought an FG (as in, purchased but it hasn't arrived yet). And I had considered that same SFG-2107 you found. But then I found the Hantek HDG2000 series and bought a HDG2012B. It's more expensive than the SFG-2107 you saw, but within the price range you mentioned. I know Hanny oscilloscopes don't have a good rep around here but haven't heard a lot about the FG.The kicker -- it's hackable. As in Rigol 1054Z style hackable. The 2012B I got is 10MHz, but with a small hack you can upgrade it to 100MHz. Turns into quite excellent value."
},
{
"post_id": "",
"author": "adamboon",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 21, 2016, 12:48:22 am",
"content": "Quote from: EEVblog on June 20, 2016, 12:25:01 pmI looked at 2 different things like that and I believe one has a square wave jitter issue and the other distorts waves asymmetrically (especially sine) as you wind up the amplification.\"System Error Message\" - It's mostly pro / studio audio and almost always analog."
},
{
"post_id": "",
"author": "Lightages",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 21, 2016, 07:31:04 am",
"content": "Wow, so much money to do a simple thing? Just run the output of your oscillator through a Schmidt buffer or inverter and buffer that with a good op amp with some variable gain or input level control. $3 worth of parts........."
},
{
"post_id": "",
"author": "System Error Message",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 23, 2016, 01:33:52 am",
"content": "Instead of splurging cash for an expensive signal gen theres a much much better signal gen but would have limited voltage. Simply get a high end soundcard, some computer software to generate the waves you wand and use it on the output. Make sure the soundcard is pogrammable. A voltage limited programmable wave gen, definitely something worth trying. perhaps EEVBlog could do a video on this on using a soundcard to generate waves as they come out as electrical signals.All you need is a PCIe to mini HDMI adapter as used for eGPUs (or even an eGPU enclosure), a PSU if one is not included and connect to your laptop/PC and run some software to make sound. Just make sure the soundcard you use has a consistent frequency response. it will take a bit of math but the output could reach Mhz depending on the output port. External soundcards can also be used too like usb and such.Seeing as it is a studio im pretty sure you should have plenty of soundcards/boards around that you can use as your signal generator."
},
{
"post_id": "",
"author": "luxfx",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "June 23, 2016, 02:52:19 am",
"content": "There are mobile app options as well -- a quick search yieldedthis iOS app. I assume it works through the headphone jack.Not being familiar with signal generators (yet!) what benefits would one get from a dedicated unit over these sound-based options? Voltage control I'm assuming. Is isolation an issue? Anything else?"
},
{
"post_id": "",
"author": "System Error Message",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 23, 2016, 03:45:52 am",
"content": "Quote from: luxfx on June 23, 2016, 02:52:19 amAccuracy. The phone's sound output isnt as accurate as a high end sound card/board. There are quite a lot of catogaries from various low end to mid and high end that can do all sorts of things. One of the important features a wave generator must have is that the output must be accurate to what you set it to do. So dont use your phone's sound jack because those have limited frequency and arent very accurate. if you're just messing around having fun and exploring than accuracy wont be a big deal but if it is professional work you need accuracy and this is one reason why dedicated signal generators are pricey."
},
{
"post_id": "",
"author": "adamboon",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 24, 2016, 01:17:52 pm",
"content": "Quote from: System Error Message on June 23, 2016, 01:33:52 amYeah - I've tried a little phone and USB / Firewire interface stuff, but found the output to be a bit ordinary - like my square waves plagued with overshoot - which is what i'm trying to test for. I haven't tried any of our very high end cards, just a couple of Pro series M-Audio and MOTU things.Quote from: luxfx on June 20, 2016, 03:07:12 pmI got excited about the Hantek - I read the first half a dozen pages of the MASSIVE eevblog post about it. all positive. I read the last half a dozen posts - everyone hated it - bugs everywhere, freezes all the time, PSU is an electrocution and/or fire hazard.I think I'll either build something, or more likely look at one of the OWON or Siglent generators. The OWON review linked was a bit long winded, and I couldn't figure out if he liked it or if it's any good or not.I did find a local deal on a used instek DDS unit, but after reading up on it - it seems to suffer from jitter like most of the other Low Frequency DDS units.It seems to go if you want a good function generator, buy a cheapish AWG - the AWG part seems to almost always be rubbish but the FG part seems okay. I wonder what you buy if you want to end up with a decent AWG?"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 24, 2016, 06:13:16 pm",
"content": "If youreallyjust want a decent quality squarewave signal then why not just go with my suggestion of a simple logic oscillator, or Lightages suggestion of a schmitt trigger to go with your existing high quality sinewave generator.If you make sure the final stage is a divide by 2 then you're guaranteed 50:50 mark:space with a very low level of jitter. Signal quality and rise time are completely under your control.Surely it's got to be quicker, easier and more satisfying than trawling through endless threads on depressingly flawed AWGs, DDS generators and phone apps."
},
{
"post_id": "",
"author": "System Error Message",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 24, 2016, 09:23:13 pm",
"content": "but in a studio you have access to the high end soundcards so all you need is software to generate the waves. Other than accuracy the phone's output is limited in things like frequency. If you only test 1 channel at a time you can use a high end soundcard and set to 192KHz i know some soundcards can generate more, really depends what you have so you probably wont have to spend any money.Otherwise building your own is cheap if you only need to test 1 wave. a wave generator is useful if you need to test various different waves."
},
{
"post_id": "",
"author": "adamboon",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 25, 2016, 12:22:51 am",
"content": "I appreciate these great suggestions. I have solved it by winning the bidding on a lightly used Siglent SDG1025. I scored it for just over a couple of hundred bucks US - which I think is excellent value. I like that it's one machine that will generate any kind of signal I might ever wish to generate (I think), and that it's independent of computers, sound cards etc. and is reasonably portable also.On a seperate note - thanks (blueskull) for the info on the Analog Discovery line, I teach an electronics/robotics class at the local library to juniors and a couple of these will be a very versatile tool for our purposes there!"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2016, 01:01:38 am",
"content": "Quote from: adamboon on June 25, 2016, 12:22:51 amCheck the latest FW is installed when you get it.http://siglentamerica.com/download/software/SDG1000-V100R001B01D01P37R3.rarAll documentation:http://www.siglentamerica.com/prodcut-wd.aspx?id=145&tid=16&T=2Thread:https://www.eevblog.com/forum/testgear/the-sdg1000-and-sdg800-thread/They can generate waveforms with *commands* to the max BW of the SDG1000 series, rf-loop explains how in the above thread, shouldn't be hard to find."
},
{
"post_id": "",
"author": "Alex Eisenhut",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2016, 01:06:31 am",
"content": "Quote from: EEVblog on June 20, 2016, 12:25:01 pmAssuming they can package it right. Mine arrived in a paper-thin box, dented front and back."
},
{
"post_id": "",
"author": "bitseeker",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2016, 05:09:44 am",
"content": "Quote from: adamboon on June 25, 2016, 12:22:51 amAh, so you were the high bidder. What a coincidence (I do seem to run into lots of forum members on eBay). Congrats! I'm glad I didn't bid higher and derail your project."
},
{
"post_id": "",
"author": "System Error Message",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 25, 2016, 11:21:50 am",
"content": "well guys perhaps we should share about what we bid on so we can argue who should get it and work together so the bids can be low.Think about it, if 2 guys kept bidding against each other the winner is gonna pay a high price, if one decides to let that particular item go (perhaps theres also another item for bidding too) than instead of multiples bidding on multiples making it expensive we can lower ebay's salary."
},
{
"post_id": "",
"author": "bitseeker",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2016, 10:20:57 pm",
"content": "I'm open to suggestions along those lines. I've done it before, so it does work when you can determine who's there, but therein lies the difficulty. There are many members, which makes coordination and timing a challenge. Maybe a mailing list or something? Using the forum just drives prices up!"
},
{
"post_id": "",
"author": "System Error Message",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 25, 2016, 10:43:45 pm",
"content": "it has to be in a members only section, to make it harder for sellers to know people are collaborating.Think of how much can be saved, no more overpriced ebay stuff."
},
{
"post_id": "",
"author": "StillTrying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2016, 11:27:40 pm",
"content": "Quote from: EEVblog on June 20, 2016, 12:25:01 pmFrequency range 0.01Hz ~ 10MHz (FY2110S)Rise and fall time of square wave 100nsI hate the way they don't use leading zero suppression on the displays of these things."
},
{
"post_id": "",
"author": "bitseeker",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2016, 11:32:23 pm",
"content": "I wouldn't go quite so far as to say there would be no more high prices. There are still crazy people on eBay who are willing to pay too much for stuff, even in the niche area of test equipment."
},
{
"post_id": "",
"author": "ez24",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 26, 2016, 03:36:47 am",
"content": "Maybe a sticky with a title like:\"Ebay test equipment I am bidding on\""
},
{
"post_id": "",
"author": "bitseeker",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 26, 2016, 03:48:22 am",
"content": "\"Stay away, please...\""
},
{
"post_id": "",
"author": "ez24",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 26, 2016, 04:00:51 am",
"content": "Corrected\"Ebay test equipment I am bidding on - Stay away - Please\"I think this would work"
}
] |
2025-10-17T19:16:12.334306
| 32
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(poll)-do-your-vias-and-pads-ever-overlap/
|
(Poll) Do your vias and pads ever overlap? - Page 1
|
[
{
"post_id": "",
"author": "sparkydog",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 08, 2024, 05:39:33 pm",
"content": "Since myoriginal questionhas seen no love, maybe a poll would be interesting?Comments welcomed if you think I missed an option!"
},
{
"post_id": "",
"author": "dino7",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "January 08, 2024, 06:15:02 pm",
"content": "I do not like via-in-pad because of the solderwick effect. Only except for when I really want to wick away heat from some device, but then again I try to via it besides the device instead of in the footprint."
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2024, 06:43:04 pm",
"content": "Every single middle ground pad on QFN packages."
},
{
"post_id": "",
"author": "isometrik",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 08, 2024, 07:09:42 pm",
"content": "There are no issues when via in pad are filled/capped, planarized, and then surface finished (ENIG) by your PCB fab house."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2024, 08:23:55 pm",
"content": "None of the above:Pads and vias may partially overlap, when the via is tented and the pad's soldermask opening doesn't quite touch the barrel of the via.Recent example.As above, via-in-pad is fine when adequate solder volume is available. QFN pads tend to have a bit too much, and the wicking helps if anything -- within reason, mind. The alternative is simply dosing less, which is also done on a regular basis.Small vias wick less; <= 12 mil (0.3mm) wick slowly, especially with lead-free. During a typical reflow cycle, they might not even fill all the way through.Single-tented and blind vias are to be avoided. Flux flows into the cavity, bubbling away, creating voids. Always fully tent, or un-tent both sides, when one side is being soldered.Note that, while you can try and tent a via within a wider pad (soldermask capping), the mask adds height, worsening planarity, and it still presents an opportunity for flux to bubble away and create voids. (Flux is lipophilic, so is soldermask and bare PCB, so it sticks around.) It's also a PITA, because you basically have to draw the soldermask opening entirely by hand.Tim"
},
{
"post_id": "",
"author": "LinuxHata",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 09, 2024, 04:43:02 pm",
"content": "Yes, I always add via, whenever possible, to the pad, because it improves mechanical strength of the pad."
},
{
"post_id": "",
"author": "Infraviolet",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2024, 07:05:53 pm",
"content": "Thinking in regard to 2 layer boards, so no blind/buried vias possible:I think some PCB manufacturers refuse to allow pad-in-via, atleast on cheaper board production options, for manufacturing reasons? Some have issues with having exposed plated copper in the same place as a via? not just because of the effect it can have at assembly stages later on.If one is hand assembling the parts on the board then one can usually overcome any solder wicking effects of the via, adding extra solder until it is full and then soldering the actual joint if it comes to that. If the manufacturer is willing to produce pad-in-via.If one has a board machine assembled then the machine wouldn't notice any wicking and that could get troublesome."
},
{
"post_id": "",
"author": "Faranight",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 09, 2024, 09:05:45 pm",
"content": "I regularly use via-in-pad's since I'm mostly doing hand-soldering, so I'm not worried about the solder-wick effect.Sometimes it also allows for easier placement of uC decoupling caps on the back side of the board when space is constrained."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2024, 04:22:19 pm",
"content": "I feel a via in pad is fine unless you've identified a production issue resulting from it.Keep the via size to a minimum.Via plugging keeps the solderwick fairies at bay."
}
] |
2025-10-17T16:42:18.631361
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(possible-or-not)read-data-from-spi-flash-memory-using-a-usb-sd-card-reader/
|
(possible or not)Read data from SPI flash memory using a USB SD card reader? - Page 1
|
[
{
"post_id": "",
"author": "zinoviy",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "February 25, 2017, 09:27:15 pm",
"content": "Hi thats my first post here!, and im happy to be here. im a beginner please be patient with me.let me explain my question,I have seen that we can use µ-controllers and arduino to read/write data using SPI with SD-CARDs.So,would it be possible to read a SPI flash memory (like Winbond) using a conventional USB SD card reader?Please, if it's possible tell me how(that would be fun), and if it isn't tell me whythanks for your attention."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 26, 2017, 12:30:41 am",
"content": "It is impossible, because SPI is just a fallback mode for SD card, and it uses protocol different from typical SPI flash ICs.SD Card readers use SD mode, not SPI."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 26, 2017, 03:35:23 am",
"content": "You could, however, make an SD card controller and connect it to an SPI flash to effectively use it as an SD card..."
}
] |
2025-10-17T19:02:20.648417
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(potentially)-noobish-questions-about-lipoliion-charging/
|
(Potentially) Noobish questions about LiPo/LiIon charging - Page 1
|
[
{
"post_id": "",
"author": "blc",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 05, 2012, 05:23:17 pm",
"content": "Hello allFirst post, new to the forum and all that. Compared to the experience on tap here I've only got a rudimentary understanding of electronics: I can follow a schematic, lay out a circuit on a stripboard and wield a soldering iron competently enough (though I haven't tackled SMD yet), but it has been a very long time indeed since I've designed my own circuit and I've never done anything as remotely complex as this. Therefore please forgive me if I've overlooked something obvious or I'm barking up totally the wrong tree. I've tried to do as much research as possible already, but I think I've hit a bit of a brick wall.I'm trying to design a mobile power supply for the Raspberry Pi. My \"rough plan\" is to have the Pi powered by a 5v boost converter (preferably one with a low-voltage dropout), and have the charging circuit and some sort of \"fuel gauge\" battery meter on the same PCB. I want the system to be able to seamlessly switch from battery power to external power when a charging cable is plugged in - in the same way that a mobile phone or laptop would do - and then revert to battery power when charging is complete and the external supply is removed. The output of the charging circuit feeds the battery, which in turn feeds both the load (the boost converter and the Pi) and the \"fuel gauge\".LiPo charging was covered way back in, but I want to be absolutely sure that I have everything correct before I even start designing anything; LiPo/LiIon batteries have the potential to be legitimately dangerous, and I don't want to mess around, even with protected cells...First of all, if I have a LiPo battery where all the cells are in parallel and properly balanced, it is my understanding that - for the purposes of charging - these can be treated as a single cell. Is this correct? Potentially I could be dealing with some pretty hefty capacities - over 2/3Ah - so I think a compact single-cell solution is out of the window. I can't find anything reasonably small with a capacity greater than 2.2Ah, which won't last long with a device that sucks around 0.6A under full load (although that entirely depends on your definition of \"reasonably small\").Second, I want this to be an in-system charger, which I understand that charger ICs can handle perfectly well. I can't quite get my head around this part though. My understanding is that charging a LiPo is a two-stage process, the first being constant current and the second being constant voltage with a steadily decreasing current. Let's assume that the load can potentially draw up to 1A, which is, conveniently enough, the charging current of the battery (these are likely to be pretty close to the real values). Let's further assume that we are in the second phase of charging and the current being supplied to the battery by the charging IC at this point is only 500mA; if the load is drawing the full current - i.e., 1A - how does the charging IC \"know\" that only 500mA is needed to charge the battery when the circuit overall will be drawing 1.5A? This is further complicated by the fact that the current consumption of the Pi may well be in constant flux; it's not going to be drawing a full load all the time, and could swing wildly in a short space of time.Furthermore, if the charging phase is in constant current mode, supplying the specified charging current of 1A, and the Pi is drawing a full load of 1A, does this mean that the charger IC will have to be able to cope with 2A? The cells I'm going to be using (or at least planning to use) for prototyping will be at least 4.4Ah, possibly up to 6.6Ah, and can sustain a maximum charging current of 0.5C. For simplicity's sake, I'll probably stick to a charging current of 1A.Thanks in advance for any help."
},
{
"post_id": "",
"author": "peter.mitchell",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 06, 2012, 03:30:52 am",
"content": "Quote from: blc on December 05, 2012, 05:23:17 pmYou can use cells in parallel as much as you want and treat them as a single cell, provided that each cell has an equal internal resistance and the connections between cells are very very low resistance, keeping them equally charged/discharged. The \"lowness\" of this resistance is dependent on charge/discharge current, due to voltage drop, more draw you need lower resistance ect.Quote from: blc on December 05, 2012, 05:23:17 pmGenerally, the cell will be charged with constant current until it reaches the cell gets to a certain voltage (generally between 4.10v and 4.18v for 4.2v lithium), then the charger switches to constant voltage.*I ASSUME*I assume, that once the voltage goes below this level again (maybe with a hysteresis) it would return to constant current. So basically if the cell is being charged, not drained the IC will maintain the CV, and the current would be limited by the draw, and if the cell is being discharged the charger wouldn't be able to maintain the higher threshold voltage so the charger would stay in CC mode.Quote from: blc on December 05, 2012, 05:23:17 pmThe charger IC will only supply what it is set to supply and will appropriately current limit itself. So the IC will only have to cope with it's set current, the issue associated with this is even though you have the IC charging, the cell will still go flat because you are drawing out more than you're putting in.Of course things vary from IC to IC and some may have features which allow more efficient charging of a battery whilst supplying a load."
},
{
"post_id": "",
"author": "blc",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 06, 2012, 06:15:43 pm",
"content": "Many thanks for the reply. I had thought I was on the right track with running cells in parallel, but it's good to have a second opinion.I've been doing a little more research this evening about this - as mentioned above, feel free to correct/slap me if I've got any of this wrong.What I wasn't clear on before is how the current is gradually reduced when it comes to the constant voltage phase: does the charging IC apply a gradually reducing current limit, or does the battery gradually draw less current and the charging IC just supplies as much current as is needed.From the reading I've done this evening, I think I understand this a little better. During the constant current stage, the charging IC just lets the battery slurp as much current as it needs - up to the programmed charging current - whilst gradually increasing the voltage. Once the constant voltage phase kicks in the battery will gradually draw less current and the charging IC just supplies as much as is needed (which will gradually reduce over time as the resting voltage of the battery approaches 4.2v).Therefore, if that is the case, then there should not be a problem - provided I can find a charging IC that can supply a current which is greater than the maximum current draw of the load. The more that the load draws, the less will be available to charge the battery - the net result being that the charging time is simply elongated.My principle challenge at this point is to source a charging IC that can supply up to 1.5 to 2A and is reasonably priced.My sources of information are the following links, in decreasing order of how useful/informative I found them:https://sites.google.com/site/tjinguytech/charging-how-tos/how-lipo-chargers-workhttps://sites.google.com/site/tjinguytech/charging-how-tos/lipo-terminologyhttp://electronics.stackexchange.com/questions/35864/lithium-ion-charging-schematic?rq=1http://electronics.stackexchange.com/questions/15722/algorithm-for-charging-li-po-batterieshttp://code-42.blogspot.co.uk/2011/03/li-po-batteries-explained-part-4.html"
},
{
"post_id": "",
"author": "digsys",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 06, 2012, 11:14:30 pm",
"content": "Quote from: blcMake it a 3rd opinion. We make up 5-15KWHr Li packs for Solar car racing (Aurora solar), and usually put 5-7 cells in parallel. Our next generationpack will have ~12 in parallel. The benefits are that neighbours can \"condition\" weaker cells, and IF a cell goes high(er) impedance, you havea LOT of redundancy !! IOW, you don't SUDDENLY lose all power and are pretty much screwed :-)Quote from: blcThis is where it gets VERY MESSY, unless you design your own Li Charger system. Manufacturer specs usually state \"if you want the longest life / bestperformance\", you MUST limit the CV current to C10, or C20 (ie1/20th C). You can definitely go higher, but the cell life will diminish.In racing we don't give a rats, and if we only get 10-20 cycles life, FINE ! But back to you -Once the IC has reached CV changeover, and as LONG AS your P/Supply can deliver FULL Load AND \"trickle\" currents, the ACTUAL current going in tothe cells will be \"around\" the correct level. In fact it will likely be a bit higher. You need to examine the manufacturers charge curves carefully, findthe CC/CV changeover point (lets assume it's 4.10V), then calculate how much over their recommended CV current (and how long) you end up.Basically, it's NOT ideal, but unless you want 100% cycle life, it won't be too bad.I have JUST finished a design (3rd gen), where I split up the DC Input into 2 paths - one SOLELY for the battery charger, so it's mostly ONLY on standby,and the 2nd path is to the DC Output. Either a PNP FET/BJT switches the battery instantly in event of Power fail. (Some people even use a tiny relay).If you go that way, you can also include a battery load test function, that puts a say 1/10 load for 5 mins, once a day.A little more work, but it's the \"ideal\" method.Quote from: blcYup, pretty close. The charger IC \"should\" ALSO limit the current to C10/C20 in CV mode, IF you want full cycle life.That's where you need to make a decision !!"
},
{
"post_id": "",
"author": "blc",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 07, 2012, 02:57:15 pm",
"content": "Excellent, many thanks for the reply.Thankfully I don't need the battery to be cope with a massive current draw, so I'll definitely be using protected cells. I'm not overly concerned about battery longevity at this point, as this isn't going to be a commercial product; it's mostly a project to get me off my lazy backside and start working with SMD. Of course it has practical applications, so I do want something that worksI think I've got a good idea of what I'm doing now, so it's on to design and part selection, methinks."
}
] |
2025-10-17T20:28:24.397327
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(pre-)amplifier-to-measure-power-supply-noise/
|
(pre-)amplifier to measure power supply noise - Page 1
|
[
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 06, 2019, 07:53:14 am",
"content": "Hello.I would like to measure noise of my linear power supply. I think I need a pre-amplifier as my oscilloscope's noise dominates the measurement. I've seen a few circuits before, but, sadly, didn't make a bookmark. So far I only found not too many circuits, one of them is this one:https://www.analog.com/en/analog-dialogue/articles/low-noise-inamp-nanovolt-sensitivity.html. Basically, it's a single IC solution using ad8248. The article suggest to put four of them in parallel to reduce the noise, but, give the price of the device, I think I'll start with one.So, what do you think of ad8248? Is it good-enough to measure some tens of microvolts? Or may be there is a cheaper alternative? I see there are quite av few low-noise opamps on the market. I don't really need it to be very accurate in terms of gain or something. It's more for comparative measurement. Bandwidth is not that important. I think 1MHz is should be fine. Gain 100-1000x, not sure how much I really need. I think the trade-off here bandwidth and gain accuracy. More gain -- less bandwidth."
},
{
"post_id": "",
"author": "iMo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 06, 2019, 12:22:12 pm",
"content": "The lowest frequency of interest?"
},
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 06, 2019, 05:30:04 pm",
"content": "10-20Hz, up to 50Hz if this makes a big difference (I want to see ripple, if any). But I'm open for suggestions. I think very low frequencies I can measure with my keithley 2000 (may be not, never tried).Basically, for me it's a learning experience, I don't really have a need for this. I just want to play with my DIY power supplies and see what and how affects stability and response."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 07, 2019, 12:23:35 am",
"content": "For a cutoff frequency that low, a low input bias current operational amplifier should be used to make the size of the input coupling capacitor reasonable. This only applies to the first stage; a majority of the gain can be in the following low impedance stage or stages.If the noise is really that low, then a differential measurement may be necessary to remove noise from ground loops."
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 07, 2019, 12:45:06 am",
"content": "if you want to test power supply, you're needs at least 3-10 MHz bandwidth, in order to be able to see possible internal oscillations in the linear regulator circuit or noise in the switching regulator."
},
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 07, 2019, 05:26:55 am",
"content": "May be I need two different amplifier? One is for low frequency measurement, the other one is with higher bandwidth (and possibly lower gain). Although ad8428 claimed to have a 3.5MHz bandwidth, which is probably enough for me.I wonder how much gain do I need. With 3MHz bandwidth I can use x1 passive probes. My oscilloscope can display signals of amplitude 10mV (noise floor is around 1mV when input is shorted). Sounds like gain of 1000 should do the job. May be I'm a bit optimistic about environment noise. I'm pretty sure I'll need to shield the preamp.BTW, the power supplies I'm going to measure are in plastic enclosure (=not shielded). So, may be, I don't even need sensitivity down to tens of microvolts due to EMI. I dunno."
},
{
"post_id": "",
"author": "iMo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 07, 2019, 06:30:17 am",
"content": "Mind the \"bandwidth\" of an opamp is always a product of the closed loop Gain and the BW.With an opamp with claimed 3.5MHz GBW and an amplification set to 100 the actual BW will be 35kHz.For 3.5MHz bandwidth and amplification of 1000 you would need an opamp with GainBW product of 3.5GHz.Therefore you need several opamps in series (AC coupled).. Like 3 opamps with 3.5MHz GBW each, set 10x gain each and as the result you'll get 1000x Gain with around 350kHz BW.FYI - below is a 2 transistors Amplifier with 72.4dB (4190x) gain, with 135kHz bandwith (30Hz-135kHz). I bet with good noise params for your application."
},
{
"post_id": "",
"author": "not1xor1",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 07, 2019, 07:32:51 am",
"content": "Quote from: imo on April 07, 2019, 06:30:17 amAD8428is aninstrumentation amplifierwith a fixed gain of 2000 and 3.5MHz is the -3dB bandwith at that amplification rate.IMHO that bandwidth should be enough for a linear PSU and if that is just an ordinary PSU (nothing related to metrology) a single AD8048 would work as well.An alternative is AD8049, with programmable gain, but the full bandwidth (15MHz) can be achieved only with a gain of 1."
},
{
"post_id": "",
"author": "not1xor1",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 07, 2019, 07:40:52 am",
"content": "Quote from: exe on April 06, 2019, 05:30:04 pmRipple is usually at 100Hz (unless you are using just a single diode instead of a rectifier bridge).In any case you need a much wider bandwidth since ripple is usually full of harmonics."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 07, 2019, 08:09:15 pm",
"content": "Quote from: radiolistener on April 07, 2019, 12:45:06 am20 MHz is common for noise measurements but lower limits are fine if direct comparisons are not needed.Quote from: exe on April 07, 2019, 05:26:55 amI commonly use my Tektronix 7A13 with a 5MHz bandwidth or 7A22 with a 1MHz bandwidth for power supply noise measurements. Higher sensitivity oscilloscopes tend to be limited to 5 or 10 MHz because of input noise considerations anyway.QuoteJust enough gain to exceed the input noise of the oscilloscope is needed. 1000x might be convenient but is pushing what is feasible without very careful construction. See below.Quote from: imo on April 07, 2019, 06:30:17 am1000x in three integrated stages of 10x each is just barely feasible without too much trouble. That is 60dB of gain however which will require very careful isolation and shielding between stages to prevent oscillation."
},
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 07, 2019, 08:51:36 pm",
"content": "Thank you very much, guys! I'll take suggestion into account and try to measure something.Quote from: imo on April 07, 2019, 06:30:17 amGood point, I had doubts about that as well. I started to look into the datasheet and it says \"[two-stage architecture] This architecture results in a 3.5 MHz bandwidth at a gain of 2000 for an equivalent gain bandwidth product of 7 GHz.\". I'm glad they are explicit about that"
},
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 07, 2019, 08:53:40 pm",
"content": "Quote from: imo on April 07, 2019, 06:30:17 amNice old-school! May be I'll start with that, before buying expensive AD devices."
},
{
"post_id": "",
"author": "not1xor1",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 08, 2019, 04:53:53 am",
"content": "Quote from: exe on April 07, 2019, 08:53:40 pmThat is a bad choice.Those AD ICs are differential amplifiers. They would take care and get rid of all common mode noise while that simple 2 BJTs amplifier will show just EMI noise in your lab.Look at\"How to measure PSU noise and ripple\"video and thread for more details."
},
{
"post_id": "",
"author": "Gerhard_dk4xp",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 08, 2019, 05:22:50 am",
"content": "Quite a strong allegation. Show me a baseline at -190 dBV with your differential amplifier.The EMI noise in my lab must be something different.<https://www.flickr.com/photos/137684711@N07/24354944411/in/album-72157662535945536/>noise density of some LEDs, 0 dB = 1 nV/rtHz, no cross correlation.regards, Gerhard"
}
] |
2025-10-17T18:13:08.719488
| 14
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(q)-feasibility-creating-a-(poor-mans)-dac-with-a-led-driver-and-current-mirror/
|
[Q] Feasibility creating a (poor-mans) DAC with a LED driver and current mirror - Page 1
|
[
{
"post_id": "",
"author": "CircuitBreaker",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2025, 06:02:41 pm",
"content": "Dear audience,In my never-ending quest to have a cheap solution for multiple calibration voltages (context: DIY synthesiser), I have come up with the following solutions in the past:[Actually built]STM32-internal DAC synchronised with GPIO output, using an SMP-08 (a stand-alone 8-channel S&H buffered IC) to have 8 quite stable voltages <- that was the ideal when I could buy it for ca. $1,1 at AliExpress (ca. $0.15 per buffered channel). That cannot be bought anymore at that price, regrettably[Read up about, but not tried]- PWM with RC filter -> but if I want 8/16 channels, I need to multiplex a lot (and synchronise a lot), and that lowers the usable PWM rate quite a bit- Cheap DAC ICs, but they will be quite a bit above $0.15 buffered per channelLately I was thinking: can't I use a bread-and-butter LED driver IC (quite cheap for multiple channels) and convert the output from constant-current to constant-voltage using either a current mirror and resistor, or perhaps directly a resistor directly attached to the driver?The thing is, I cannot find any info whether that's feasible, since all hits I get when searching for this really focus on using it with LEDs, not how to use it for constant-voltage output (which is understandable, since that's the primary use case after all).So my question to you is: a) do you think it is feasible at all? b) do you have any actual experience doing this?(and side question: what other poor-mans DAC for control voltages can you think of that cost ca. $0.15 per channel, buffered?)Thanks for reading!"
},
{
"post_id": "",
"author": "petemate",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 01, 2025, 08:47:32 pm",
"content": "The answer to these kind of questions always end up being about your specific requirements. What are your stability requirements for your calibration requirements?PWM with RC filter can be as stable as you want if you just add enough lowpass filtering(and then stuff like component noise comes into play), but your transient performance will suffer.You can probably use a LED IC driver, but they probably aren't that stable - especially the switching ones. You'll also need to adapt your receiving end to whatever voltage that the LED driver expects to see - they probably have some sort of over- and under-voltage triggers that you'll need to navigate.why not just use a DAC instead?a) Feasible? Yes, to some degree of stability. b) No, I do not. I would definitely go with a more tried-and-true solution."
},
{
"post_id": "",
"author": "Smokey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2025, 09:55:26 pm",
"content": "\"Cheap\" as in $0.15 and \"Calibration\" don't mix.Your LED driver probably also has terrible resolution since it's designed to dim an LED not make a highly accurate and stable voltage reference. So you probably get, what, 64 steps? Maybe 256? You can get an 8bit DAC for practically nothing and, as you noted, it's built in to many microcontrollers."
},
{
"post_id": "",
"author": "langwadt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2025, 09:59:57 pm",
"content": "why not 8/16 pwm outputs? the stm32 has plenty of timers"
},
{
"post_id": "",
"author": "CircuitBreaker",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 02, 2025, 06:36:47 am",
"content": "Hi, thanks for replying. Regarding your points:Quote from: petemate on October 01, 2025, 08:47:32 pmYes. The idea is that I'd do that and that I'd use the voltages for relatively stable offsets -> really to calibrate certain offsets that you would normally use single-setup potmeters for (so no \"musical\" transients like e.g. filter frequency, OSC frequency, etc.)So I indeed have no problems with e.g. a 10 Hz cut-off for the PWM filter.Quote from: petemate on October 01, 2025, 08:47:32 pmThanks for that insight -> that's something I didn't think of. Perhaps I need to just build it and see how it behaves.Quote from: petemate on October 01, 2025, 08:47:32 pmHonest to god -> to try to have an overall BOM cost of a single \"voice module\" that is as low as possible. Am prepared to do more in software like calibration, etc. to make up for it. And, since it's a hobby project -> to see how far I can go that route before giving up and say \"let's just use a DAC and accept the cost\".Maybe I need to fall back to a \"fixed, hand-calibrated\" potmeter solution; I just had really liked to firmware-auto calibrate most parts of the voice module - so that manual re-tuning would not be needed.Second point; if I have 1 DAC, I need to multiplex that for multiple voltages (they way I did with the SMP08), and I'd need to build an additional S&H per channel - basically re-building the SMP08 in discrete. Maybe thatisthe best way. Who knows...Quote from: petemate on October 01, 2025, 08:47:32 pmThanks for the input. I'll consider it."
},
{
"post_id": "",
"author": "CircuitBreaker",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 02, 2025, 06:43:36 am",
"content": "Quote from: Smokey on October 01, 2025, 09:55:26 pmThat is good input. Perhaps the resolution would indeed be too low. Had, however, hoped that e.g. a 10-bit LED PWM driver would be sufficient. Would have to measure it then.Regarding the DAC - same point as I wrote above: An LED driver IC has multiple PWM outputsin parallelthat was the whole point of trying out this route. With only 1 (additional) DAC at my disposal in the MCU, I'd need to multiplex it; which has its own BOM cost effect and switching issues with it.Now, PCB real estate is not yet a prohibiting factor, so maybe indeed using an external DAC per channel is the solution. But IIRC 12-bit DACs are also quite a bit above the $0.15 per channel. But maybe I didn't look well enough... I'll have a look at that again.Do you perhaps have a cheap (12-bits) DAC IC in mind that doesn't cost (much) above ca. 15-20 ct. per channel?"
},
{
"post_id": "",
"author": "CircuitBreaker",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 02, 2025, 06:47:18 am",
"content": "Quote from: langwadt on October 01, 2025, 09:59:57 pmDedicated GPIO outputs per voltage needed you mean? So, no multiplexing?I'd need to look that up, I thought that for reasonably cheap MCUs - think F0, G0, and the like - you only have 4 dedicated mappable PWM HW outs (even when you would have pins enough).-> But, good idea, I need to look that up for newer MCUs, thanks! Just tried it out with the newest STM32CubeMX -> for a G431C6U, I can actually map 22 HW pins to PWM channels (probably fewer, since I need timers for other stuff as well, but still)! So, that might actually be a good route. Thanks for the hint."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 02, 2025, 09:58:51 am",
"content": "The ROHM BU2506FV-E2 might just meet your stinge point without any additional mickey mouse circuitry.www.lcsc.com/product-detail/C184386.html"
},
{
"post_id": "",
"author": "CircuitBreaker",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 02, 2025, 10:45:06 am",
"content": "Quote from: Terry Bites on October 02, 2025, 09:58:51 amThanks! I'll look into it. Ah.Bufferedas well! Great."
},
{
"post_id": "",
"author": "petemate",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 02, 2025, 10:34:20 pm",
"content": "Quote from: CircuitBreaker on October 02, 2025, 06:36:47 amYou could consider an alternative option: Some sort of resistor ladder. If you have enough GPIOs, or you are wiling to throw demux ICs at it, you can build a DAC from just resistors, which are basically free. If PCB area isn't an issue, that could be a solution. Especially considering if your alternative is potentiometers.Quote from: CircuitBreaker on October 02, 2025, 06:36:47 amI'm currently repairing a device that does exactly this. One DAC fed into a 4051, which then has a film capacitor on each output. As long as the load is negligible(in this case its buffered by some opamps), you can probably get away with it."
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2025, 12:19:48 pm",
"content": "Quote from: petemate on October 02, 2025, 10:34:20 pmAnd providing you can tolerate the noise from the inevitable charge injection during channel switching."
},
{
"post_id": "",
"author": "CircuitBreaker",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 06, 2025, 06:29:14 pm",
"content": "Thanks for (all) your advice!I'll probably go for this IC first:www.lcsc.com/product-detail/C184386.htmlThe only thing I'm a bit afraid of is that I have no (cheap) option when that is out of stock or not being fabricated anymore -> that IC isso muchcheaper than comparable alternatives, that when it's not available anymore, I'd probably have to rethink the design (not just buy a different IC)But that'll be worry for later..."
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2025, 09:37:00 pm",
"content": "The Microchip MCP48FVB18 is reasonably priced, 10bit 8ch like the Rohm part:https://www.microchip.com/en-us/product/MCP48FVB18"
}
] |
2025-10-17T16:13:47.968042
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(q)-ina226-and-low-side-current/
|
[Q] INA226 and low-side current sensing - Page 1
|
[
{
"post_id": "",
"author": "AlxDroidDev",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 29, 2016, 04:45:27 pm",
"content": "For my electronic load project, I decided to use aTexas' INA226. If I went with the INA219 (high-side only), I'd have to use 2 shunt resistors: one, high-side, for the INA219, and another one, low side, for the opamp's feedback. Plus the INA219 is limited to 26V, and I'd like to go up to 30V.1) Using the INA226, I can share the same shunt resistor for the INA226 and the opamp feedback, correct?2) If I understood the INA226 datasheet correctly, when used on the low-side, it must be the last device in the current loop before ground. Is that correct? Is so, it means I cannot use this project as a constant current source for other devices that I'd connect after the load, such as a battery I wish to charge or a LED I wish to test.3) Does the VBUS pin always have to be connected to the Vin pin? Can I connect the VBUS pin to the high side of the load, before the FET?thank you!"
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 29, 2016, 05:31:24 pm",
"content": "The INA226 can measure two voltages, a smaller one between the two inputs for the shunt and a second one between GND and VBus. Its is up to you to decide where to have the inputs. The main thing is to have less than 36 V at any input relative to GND. So the shut can be high side or low side or somewhere in the middle if you like and have two loads in series. So if a 30 V outout is planed the raw voltage before regulation might be to high under wirst case conditions."
},
{
"post_id": "",
"author": "AlxDroidDev",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "February 02, 2016, 09:57:51 pm",
"content": "Quote from: Kleinstein on January 29, 2016, 05:31:24 pmVielen Dank!"
}
] |
2025-10-17T19:25:30.307938
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(q)-transistor-question/
|
[Q] Transistor question - Page 1
|
[
{
"post_id": "",
"author": "itvend",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 02, 2014, 11:46:17 am",
"content": "Hy.So i have little circuit and why does collector output signal does this, it goes 60us longer before dropping to 0V."
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 02, 2014, 11:59:30 am",
"content": "You need to take care about where the scope trigger occurs - at the moment you appear to be looking at each signal independently - i.e. the time is not correlated."
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 02, 2014, 12:02:09 pm",
"content": "Andy's right, the signals aren't correlated. But you're also right, the timing is off - but it's actually taking too long to rise back to 12V, not drop down to 0V.You're likely seeing the transistor'sstorage timeor storage delay. When the transistor saturates, you store excess charge onto the base; this charge must be removed (slowly) to switch off.Try aBaker clampto hold the transistor right on the threshold of saturation:Edit - er, or not. Your input waveform is asymmetric too, and the time is perhaps a bit too long to be storage time.Something to keep in mind, anyway."
},
{
"post_id": "",
"author": "Bored@Work",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 02, 2014, 12:28:34 pm",
"content": "Quote from: Andy Watson on May 02, 2014, 11:59:30 amAnd what he missed when \"aligning\" the waveforms is that the transistor stage inverts. The input has shorter on than off times, so the output has shorter off than on times."
},
{
"post_id": "",
"author": "itvend",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 02, 2014, 12:49:51 pm",
"content": "Thanks guy-s for good infonow its with correct triggers"
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 02, 2014, 10:39:33 pm",
"content": "Quote from: Bored@Work on May 02, 2014, 12:28:34 pmAnd it took a grumpy old Greybeard to notice!"
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 03, 2014, 01:24:27 pm",
"content": "What make and model of DSO like that supports independent triggering?I am used to seeing that kind of mistake on analog oscilloscopes which support alternate triggering."
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 03, 2014, 03:56:59 pm",
"content": "What piece of shit scope allows moving one trace in respect to another ? (Apart from probe skew alignment of course)I have growled multiple times at scopes that cannot time-lock traces. Example : throw something in memory, then tap a live signal, hit single shot or stop, start scrolling , the memory traces stay , only the live ones scroll... Totally useless if you want to do a comparision between an earlier captured signal and what you just captured. Timelock is broken. All visible traces should scroll in sync when operations on timebase or trigger position are done post-capture.Of course the scope input stage must allow for skew between channels to compensate cable and probe length , but that compensation happens BEFORE viewport manipulations."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 03, 2014, 04:13:53 pm",
"content": "Quote from: free_electron on May 03, 2014, 03:56:59 pmSome allow a trace to be \"unlocked\" so they may be shifted horizontally relative to the others.A more common problem at least with analog oscilloscopes is alternate triggering while in alternate instead of chop mode which destroys the displayed phase relationship between traces. It is doubly annoying when a DSO does it. The solution is to force the trigger to only use one channel or to use chop mode.QuoteI agree that it should happen first but probe skew is usually an insignificant source of error on slow oscilloscopes. I have only seen it compensated for significantly above 100 MHz and never as part of the horizontal positioning except in very special circumstances like when using a current probe or active probe."
}
] |
2025-10-17T20:02:52.628266
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(q)-what-are-these-parts/
|
[Q] What are these parts? - Page 1
|
[
{
"post_id": "",
"author": "fusionimage",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 30, 2015, 04:09:18 pm",
"content": "hi! this is an old garage door opener from 1991.i would like to know, of these parts are inductivities and what colorcode they use?they have 5-6 pins"
},
{
"post_id": "",
"author": "nitro2k01",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 30, 2015, 04:15:34 pm",
"content": "Those look like trimmers (could be resistive, capacitive or inductive) and the dabs of paint probably just mean that the trimmer in question was calibrated."
},
{
"post_id": "",
"author": "daqq",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 30, 2015, 04:18:09 pm",
"content": "Shielded tunable coils. Some of them might have a capacitor or some misc extra parts inside, but most of it is the inductor. You tune it by adjusting the height position of the ferrite core."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 30, 2015, 04:18:25 pm",
"content": "Those are adjustable inductors: slug-tuned coils. They presumably tune the opener to the RF operating frequency."
},
{
"post_id": "",
"author": "w2aew",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 30, 2015, 04:20:48 pm",
"content": "Quote from: fusionimage on April 30, 2015, 04:09:18 pmThey're certainly either adjustable inductors or IF transformers. Unless there are some part number markings printed or stamped into the metal housings, you'd have to remove them to measure them. You could use a technique like this video to measure them, whether they are inductors or tuned IF coils or transformers:"
},
{
"post_id": "",
"author": "fusionimage",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 30, 2015, 04:27:57 pm",
"content": "thanks a lot!"
},
{
"post_id": "",
"author": "mathias",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 30, 2015, 04:41:19 pm",
"content": "Tunable inductor is indeed most likely, but there also exist helical filters of this shape and size."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 30, 2015, 05:08:41 pm",
"content": "With the age of that board that is not likely. Most likely the one on the bottom left is a 455kHz oscillator to do FM modulation on the crystal. the top 2 are to select harmonics of the crystal before they go to the final amplifier and the output tuned circuit, the black coil on the left with the thick silvered wire."
},
{
"post_id": "",
"author": "fusionimage",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 15, 2015, 09:33:33 am",
"content": "Ok, I'll try to reverse engineer itfyi: the transmission frequency is ~40MHz"
}
] |
2025-10-17T19:40:39.958324
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(question)-circuit-with-diodes-and-zener-diodes-for-various-voltages/
|
[Question] Circuit with diodes and zener diodes for various voltages - Page 1
|
[
{
"post_id": "",
"author": "krd777",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 01, 2010, 04:12:42 pm",
"content": "Hi everyone!I'm having some doubts here and i can't find the proper answer anywhere.It is I can't remember the models for diode circuit analysis.I've started to try to get the answers but I need to make sure they're correct.So:if I have a silicone diode D1 with a junction voltage Vj of 600mV and a resistance Rr of 10 ohm.When I connect it in series with a voltage source Vdc and a resistor R1 of 1k ohm.To analyze this circuit, when Vdc is 5V and the diode is directly polarized (ON).-Can I substitute the diode for a voltage source equal do Vj in series with a resistor equal to Rr to represent the voltage drop along D1?Also, if Vdc is equal to Vj, can I assume the diode is ON but the current through it is zero? Or should it be behaving like open circuit?Also, if Vdc is smaller than Vj but bigger than zero, Should I assume the diode as being only a resistor? Or should it be behaving like open circuit?Also, if Vdc is maller than zero should I assume the diode is OFF and behaving like an open circuit? (I say this because the reverse current is so small in the junction)Sorry for all these questions but I didn't pay attention in class and I can't find it anywhere on my books. So I'm trying to design these models myself.My biggest doubts is what to consider when Vdc is between zero and Vj. Should it be a resistor like Rr? Doesn't seem to make much sense.Thanks in advance and if I explained it badly, please tell me, I can try better."
},
{
"post_id": "",
"author": "DJPhil",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 01, 2010, 08:52:17 pm",
"content": "Fair warning, this is off the top of my head with a little googling.Quote from: krd777 on December 01, 2010, 04:12:42 pmApproximately, but not accurately for analysis (or probably schoolwork). The circuit has no Thevanin equivalent, for example, due to the VI curve of the PN junction.Quote from: krd777 on December 01, 2010, 04:12:42 pmThis I don't quite understand. Practically speaking there will be some leakage current, but I can't reconcile the diode being ON with zero current as a sane state of affairs. Semantics aside, this might make a lot more sense if you study a VI curve. The more ideal the diode model you use, the steeper the curve. An ideal diode curve is zero to Vj, then instantly vertical. A diode with Vj applied is beginning it's linear region, and should be passing current equal to Vdc/Rr+R1. I doubt this would satisfy a professor though.Quote from: krd777 on December 01, 2010, 04:12:42 pmThis is a bit easier. Now you'd be sitting on the bottom of the VI curve and the only factor is leakage, which is much smaller than I = Vdc/Rr. This is almost certainly regarded by academia to be an open circuit.Quote from: krd777 on December 01, 2010, 04:12:42 pmYes, right up until you hit zener (avalanche) breakdown, at which point the diode starts conducting heavily.Quote from: krd777 on December 01, 2010, 04:12:42 pmI'd dig in to wikipedia, or google, with a handful of keywords. VI curve, zener, linear region, and the like should get you started. You can also lean onthe open textbook at All About Circuitsfor formulas and the like.Hope that helps."
},
{
"post_id": "",
"author": "scrat",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 01, 2010, 09:38:17 pm",
"content": "Diode circuits are quite confusing, if you don't find a \"method\" to procede solving them. Particularly if you try solving circuits with diodes and opamps...The simplest way that I have found is to suppose the diode as open, as a first thing, which is usually easy to calculate (in the OFF state current is known, while in the ON you only know it's positive). Then, if the resulting voltage is higher than the threshold, the OFF state is not consistent, and you are sure the diode is ON. In this last case, you substitute the diode with the voltage+resistor.This is right also for Zener zone, you just have to consider the proper voltage value and direction.For some circuits with multiple diodes, you should consider all of the cases, preferably starting with the OFF state.I also found useful to consider current direction when inductances are connected to diodes (as usual in power switching circuits).Besides all of this, one always have to use good sense, and discard solutions that are not consistent, or intuition to rapidly solve.A rule that always applies to physical systems is that if the model is right and you find one solution, that is the RIGHT solution. So, if you analyse one of the diode states and find it is consistent, then you have found the solution.BTW, null current and voltage equal to the threshold is at the limit between OFF and ON state, but a component with null current is simply equivalent to an OPEN circuit."
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 01, 2010, 09:43:11 pm",
"content": "My $0.02 (not fact checked either):Quote from: krd777 on December 01, 2010, 04:12:42 pmThe IV curve of a resistor is linear, and an (ideal) diode is exponential, so it won't be a very good approximation. But it's a first order approximation, which may do in some cases. In other cases, it will get you in trouble, like your next question.Quote from: krd777 on December 01, 2010, 04:12:42 pmThe ideal pn junction has an exponential IV curve (as long as Vj >> VT*someconstant, which is something like 25mV at room temperature), so at Vdc = Vj(somecurrent), the current will just equal to somecurrent. Eg. the forward voltage may be 300mV at 1uA, 500mV at 1mA and 700mV at 1A (made up numbers, check a real datasheet for actual data). So if you apply 500mV, the current should be 1mA.Quote from: krd777 on December 01, 2010, 04:12:42 pmThe exponential curve will allow some current to flow unless the forward voltage approaches VT. A resistor sounds like a pretty bad approximation.Quote from: krd777 on December 01, 2010, 04:12:42 pmThe reverse leakage current will flow, which is a constant (first order approximation, depends on temperature and probably tons of other factors in real life).Quote from: DJPhil on December 01, 2010, 08:52:17 pmMost diode models I know at least model some kind of exponential function, the step curve is mainly used at the very basic level (and things like digital systems were it usually doesn't matter)."
},
{
"post_id": "",
"author": "krd777",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 03, 2010, 09:16:13 am",
"content": "Alright everyone, thank you so much for the answers. Based on what you guys said, I'll use a voltage source and resistor in series to replace the diode for the ON mode. For OFF mode I shall replace it with an open circuit. Same way of thinking for Zener region.I'll confront my teacher with these models and see what she might say. Then I'll come back to let you know if they were accepted. Byt the way, using these models gave me correct results, so following what has been said above, I assume tthey're correct.Again, thank you very much and I shall be back with answers.Best regards,krd777"
}
] |
2025-10-17T20:41:23.235257
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(question)little-programming-question/
|
[QUESTION]Little programming question - Page 1
|
[
{
"post_id": "",
"author": "anker_by",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 07, 2017, 06:26:25 pm",
"content": "Hello everyone, I want to know if Pythong works across with micro processor, electronics... etc... sorry for noob question...Regards,- Anker_by"
},
{
"post_id": "",
"author": "daybyter",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 07, 2017, 06:50:43 pm",
"content": "Checkhttps://micropython.org/"
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 08, 2017, 04:18:54 am",
"content": "Quote from: anker_by on September 07, 2017, 06:26:25 pmNo need to apologise - thisisthe Beginners section."
}
] |
2025-10-17T18:49:17.147075
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(questionadvice)-adaptiveintelligent-lighting-system-planning-and-parts/
|
[Question/Advice] Adaptive/Intelligent Lighting System - Planning and Parts - Page 1
|
[
{
"post_id": "",
"author": "superheromario",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 16, 2021, 04:41:52 pm",
"content": "Hi guys,I think this is the first time I post here and I am not sure if it's the appropriate place to do so, so please guide me out if it isn't. Thank you.I sort of have some spare time while waiting for my job application, and so I'm thinking of something to fill in my gap time cause I don't play games anymore.I want to have a lighting control system in my room (which is about 10-12 metres square).I am thinking of using the Pi 4 as the controlling board, with a number of sensors around my place. At first I thought of some proximity sensors, then I thought of IR, but then I had this problem where I thought that IR could easily be spoiled by other source of heat in the room. So for the time being I am not even sure which sort of sensor I should be using. Would love to hear form your advice.Next thing I am thinking of using batteries with a simple and small board, for example what comes to my mind is a board from STM32, like the one I used in my school, that can communicate using Bluetooth for example. But I don't know if there's any other better option. Because if not using batteries then I need to route all the wires in my room, which is what I want to avoid.About the idea, maybe you will ask why not just use an IR device available on the market, which if I look for, I could easily find one for about less than 40 euros. But there's problem with those things, they only detect movement, while in my plan, I want the light to be on even when I am idle. I have sort of an idea about how things work in my mind, though I haven't sketched anything. I want the room to be lit as long as I am awake, working (I will define exactly what that means later), and when I am about to sleep (for example when I lie down), the lights turn off.About the lights, at first I thought of using simple transistors to control the electricity but there's couple of problems which I am not very confident on, I am not very good at Physics in the past, so I am not sure if it's okay to let AC flow through the transistor. That's for starters, and I am quite scared of letting the wires running and that there's a chance there's electricity leak somewhere (but I'll work that part out). I have a second thought where I might end up using LED's (or LED strips) for this, but I'm wondering if a bunch of LED's could provide the same amoung of illuminations as the light bulbs.Well that should be all for now and by all means, thank you for reading the messy post. Wish you all a gread day/night ahead.Love from Vitry."
}
] |
2025-10-17T17:35:29.151798
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(raspberry-pi)-3-5-inch-display-rotation-does-not-work/
|
[Raspberry pi] 3.5 inch display - rotation does not work - Page 1
|
[
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 05, 2024, 11:03:29 am",
"content": "Hello!This week I started learning about Raspberry PI 4B and a 3.5 inch MHS display - the same model as described here:http://www.lcdwiki.com/MHS-3.5inch_RPi_DisplaySo the drivers come from github from goodtft, updated basically on a regular basis:https://github.com/goodtft/LCD-showFirst of all, I installed Raspberry PI OS. Unfortunately, I realized I didn't have a MicroHDMI cable, so I had to settle for VNC to start with. Thanks to this, I managed to connect remotely to Raspberry before I could even install the LCD driver.Unfortunately, due to my ignorance, I started installing the driver for the Waveshare 3.5 inch display instead of MHS, then I simply formatted the SD card with Raspberry OS and installed everything again. Then I started working on the LCD driver for the MHS display according to the guide from the link a few lines above. And it installed.Now I control it via VNC and everything can be seen on the LCD, or control it on the LCD itself (touch screen function works). However, it turns out that the screen rotation option is somehow disabled permanently and changing the parameters related to it does not affect it.According to some information from the Internet, it should be possible to set it this way:a) Using the following commands -nothing changed for me:Code:cd LCD-show/sudo ./rotate.sh 90b) By reinstalling and setting the rotation at the very beginning -nothing changedCode:sudo rm -rf LCD-showgit clone https://github.com/goodtft/LCD-show.gitchmod -R 755 LCD-showcd LCD-show/sudo ./MHS35-showc) By getting into theconfig.txtfile and trying to change this value \"90\"; this didn't change anything, so I also tried changing the name mhs to tft35a, and then mhs35 to piscreen,drm (To make sure that the manufacturer did not deceive me with the print on the silkscreen):Code:dtoverlay=mhs35:rotate=90Code:# For more options and information see# http://rpf.io/configtxt# Some settings may impact device functionality. See lin># uncomment if you get no picture on HDMI for a default >#hdmi_safe=1uncomment the following to adjust overscan. Use positi># goes off screen, and negative if there is too much bor>#overscan_left=16#overscan_right=16#overscan_top=16#overscan_bottom=16uncomment to force a console size. By default it will ># overscan.#framebuffer_width=1280#framebuffer_height=720uncomment if hdmi display is not detected and composit>#hdmi_force_hotplug=1# uncomment to force a specific HDMI mode (this will for>#hdmi_group=1#hdmi_mode=1uncomment to force a HDMI mode rather than DVI. This c># DMT (computer monitor) modes#hdmi_drive=2# uncomment to increase signal to HDMI, if you have inte># no display#config_hdmi_boost=4# uncomment for composite PAL#sdtv_mode=2uncomment to overclock the arm. 700 MHz is the default.#arm_freq=800# Uncomment some or all of these to enable the optional >#dtparam=i2c_arm=on#dtparam=i2s=on#dtparam=spi=onUncomment this to enable infrared communication.#dtoverlay=gpio-ir,gpio_pin=17#dtoverlay=gpio-ir-tx,gpio_pin=18# Additional overlays and parameters are documented /boo>Enable audio (loads snd_bcm2835)dtparam=audio=on# Automatically load overlays for detected camerascamera_auto_detect=1Automatically load overlays for detected DSI displ>display_auto_detect=1# Enable DRM VC4 V3D driver#dtoverlay=vc4-kms-v3dmax_framebuffers=2Run in 64-bit modearm_64bit=1# Disable compensation for displays with overscandisable_overscan=1# Enable host mode on the 2711 built-in XHCI USB con># This line should be removed if the legacy DWC2 con># (e.g. for USB device mode) or if USB support is no>otg_mode=1# Run as fast as firmware / board allowsarm_boost=1hdmi_force_hotplug=1dtparam=i2c_arm=ondtparam=spi=onenable_uart=1dtoverlay=mhs35:rotate=90hdmi_group=2hdmi_mode=1hdmi_mode=87hdmi_cvt 480 320 60 6 0 0 0hdmi_drive=2For now, the screen still doesn't rotate. Thanks to this, I always have the screen with the power cable facing down, which makes it difficult to place it normally. I checked this error by installing Raspberry Pi OS 64-bit and then 32-bit (both viaRaspberry Pi Imager v1.8.5, released 2024-03-15)Is it possible that something has been messed with in the RPI settings since these reinstallations, that the screen rotation option is blocked, or am I just doing something else very wrong? I will be grateful for your help.RegardsBogdan"
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 05, 2024, 11:38:19 am",
"content": "Perhaps it simply defaults to 90 degree rotation, as many of these small screens are actually portrait orientation by default?That is, have you tried e.g.sudo ./rotate.sh 0orsudo ./rotate.sh 180?Also, you do realize you need to reboot the Pi for the new rotation to take effect; it is not immediate?"
},
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 05, 2024, 12:28:02 pm",
"content": "Hi, thank you for your reply!Yes, I am aware of the need to restart the raspberry after such operations. For me, after performing the operation from the Terminal available in Raspberry OS, the situation is as follows:1) command:Code:sudo ./rotate.sh 0(followed by:Code:sudo reboot)will cause the following lineCode:dtoverlay=mhs35:rotate=90to remain in the config.txt file (so nothing will change)2) command:Code:sudo ./rotate.sh 180provides the return text as follows:LCD rotate value is set to 180reboot nowHowever, this time the system resets itself. After restarting, the following entry appears in the config.txt file:Code:dtoverlay=mhs35:rotate=270So you can see that the value in config.txt is somehow shifted forward by 90.3) EnteringCode:sudo ./rotate.sh 0will once again cause the system to reset itself and the value in config.txt will return to 90.The visual orientation of the image on the screen is still the same after each of these steps (i.e. with the power port facing down)."
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 05, 2024, 01:34:22 pm",
"content": "TheMHS35-Showscript you use, can install xserver-xorg-input-evdev fromhttp://mirrors.zju.edu.cn/raspbian/raspbian,which makes myself a bit, uh, suspicious... but really, it is just horribly shoddy work; bad enough to make my eyes bleed.Anyway, it seems to using the\"standard\" fbtftdriver, just configuring it differently for specific displays. As you do get a display, the driver is already installed, it's just its configuration that needs fixing. For MHS35, the base device tree overlay (mhs35-overlay.dtb) you should see in your/boot/overlays/mhs35.dtb0, containsCode:/dts-v1/;/ {compatible = \"brcm,bcm2835\\0brcm,bcm2708\\0brcm,bcm2709\";fragment@0 {target = <0xdeadbeef>;__overlay__ {status = \"okay\";spidev@0 {status = \"disabled\";};spidev@1 {status = \"disabled\";};};};fragment@1 {target = <0xdeadbeef>;__overlay__ {tft35a_pins {brcm,pins = <0x11 0x19 0x18>;brcm,function = <0x00 0x00 0x00>;linux,phandle = <0x01>;phandle = <0x01>;};};};fragment@2 {target = <0xdeadbeef>;__overlay__ {#address-cells = <0x01>;#size-cells = <0x00>;tft35a@0 {compatible = \"ilitek,ili9486\";reg = <0x00>;pinctrl-names = \"default\";pinctrl-0 = <0x01>;spi-max-frequency = <0x6dac2c0>;txbuflen = <0x8000>;rotate = <0x5a>;bgr = <0x00>;fps = <0x1e>;buswidth = <0x08>;regwidth = <0x10>;reset-gpios = <0xdeadbeef 0x19 0x01>;dc-gpios = <0xdeadbeef 0x18 0x00>;debug = <0x00>;init = <0x10000f1 0x36 0x04 0x00 0x3c 0x0f 0x8f 0x10000f2 0x18 0xa3 0x12 0x02 0xb2 0x12 0xff 0x10 0x00 0x10000f8 0x21 0x04 0x10000f9 0x00 0x08 0x1000036 0x08 0x10000b4 0x00 0x10000c1 0x41 0x10000c5 0x00 0x91 0x80 0x00 0x10000e0 0x0f 0x1f 0x1c 0x0c 0x0f 0x08 0x48 0x98 0x37 0x0a 0x13 0x04 0x11 0x0d 0x00 0x10000e1 0x0f 0x32 0x2e 0x0b 0x0d 0x05 0x47 0x75 0x37 0x06 0x10 0x03 0x24 0x20 0x00 0x100003a 0x55 0x1000011 0x1000036 0x28 0x20000ff 0x1000029>;linux,phandle = <0x02>;phandle = <0x02>;};tft35a-ts@1 {compatible = \"ti,ads7846\";reg = <0x01>;spi-max-frequency = <0x1e8480>;interrupts = <0x11 0x02>;interrupt-parent = <0xdeadbeef>;pendown-gpio = <0xdeadbeef 0x11 0x01>;ti,x-plate-ohms = [00 3c];ti,pressure-max = [00 ff];linux,phandle = <0x03>;phandle = <0x03>;};};};__overrides__ {speed = <0x02 0x7370692d 0x6d61782d 0x66726571 0x75656e63 0x793a3000>;txbuflen = [00 00 00 02 74 78 62 75 66 6c 65 6e 3a 30 00];rotate = [00 00 00 02 72 6f 74 61 74 65 3a 30 00];fps = [00 00 00 02 66 70 73 3a 30 00];bgr = [00 00 00 02 62 67 72 3a 30 00];debug = <0x02 0x64656275 0x673a3000>;swapxy = <0x03 0x74692c73 0x7761702d 0x78793f00>;};__symbols__ {tft35a_pins = \"/fragment@1/__overlay__/tft35a_pins\";tft35a = \"/fragment@2/__overlay__/tft35a@0\";tft35a_ts = \"/fragment@2/__overlay__/tft35a-ts@1\";};__fixups__ {spi0 = \"/fragment@0:target:0\\0/fragment@2:target:0\";gpio = \"/fragment@1:target:0\\0/fragment@2/__overlay__/tft35a@0:reset-gpios:0\\0/fragment@2/__overlay__/tft35a@0:dc-gpios:0\\0/fragment@2/__overlay__/tft35a-ts@1:interrupt-parent:0\\0/fragment@2/__overlay__/tft35a-ts@1:pendown-gpio:0\";};__local_fixups__ {fixup = \"/fragment@2/__overlay__/tft35a@0:pinctrl-0:0\\0/__overrides__:speed:0\\0/__overrides__:txbuflen:0\\0/__overrides__:rotate:0\\0/__overrides__:fps:0\\0/__overrides__:bgr:0\\0/__overrides__:debug:0\\0/__overrides__:swapxy:0\";};};which basically describes the display (and touch screen) configuration.See the linerotate = <0x5A>;?<0x5A> = <90>, so it definitely defaults to 90 degrees of rotation.(Note that if you installdevice-tree-compilerpackage, you can convert .dtb and .dtbo files to sources usingdtc -I dtb -O dtsfilenamesource-filenameand sources to device tree blobs or overlays usingdtc -I dts -O dtbsource-filenamefilenamebut as your display is a standard ILI9486 one using SPI and configured via device tree, you don't need to.)TheMHS35-Showscript also adds the following lines to your/boot/config.txt:Code:hdmi_force_hotplug=1dtparam=i2c_arm=ondtparam=spi=onenable_uart=1dtoverlay=mhs35:rotate=90hdmi_group=2hdmi_mode=1hdmi_mode=87hdmi_cvt 480 320 60 6 0 0 0hdmi_drive=2where you should take note of thedtoverlay=mhs35:rotate=90line.If you have runMHS50-Showscript more than once after installing Raspbian, you will have multiple copies of the above settings in/boot/config.txt. Use your favourite editor, for examplenano, to edit it and remove the extra copies:sudo nano /boot/config.txtIn nano, Ctrl+K deletes the current line, Ctrl+O saves the file, and Ctrl+X exits (as shown at the bottom of the editor window, with ^ being the Linuxy/Unixy abbreviation for the Control key).After you have done that, you should only need to run one ofsudo sed -i -e 's|^\\(dtoverlay=mhs35:rotate\\)=.*$|\\1=0|g' /boot/config.txtsudo sed -i -e 's|^\\(dtoverlay=mhs35:rotate\\)=.*$|\\1=90|g' /boot/config.txtsudo sed -i -e 's|^\\(dtoverlay=mhs35:rotate\\)=.*$|\\1=180|g' /boot/config.txtsudo sed -i -e 's|^\\(dtoverlay=mhs35:rotate\\)=.*$|\\1=270|g' /boot/config.txtand reboot, to change the rotation of your display. (The above only changesdegreeson thedtoverlay=mhs35:rotate=degreesline, which you can do equally well using e.g.sudo nano /boot/config.txtif you prefer. Just remember to reboot afterwards for the change to take effect.)"
},
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 05, 2024, 03:10:11 pm",
"content": "I'm not sure I understand everything correctly.I have not experienced any duplication of any lines in the config.txt file. When I try to make changes both via the command line and directly in the config.txt file, I still have 93 lines of text in the config.txt file, just like in my first post, where I also inserted the content of the config file.The problem is that all the changes in the config.txt file that are saved successfully are ignored by the raspberry itself and do not change the screen orientation. It's as if the kernel completely ignored what changes in the config file."
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 05, 2024, 05:26:51 pm",
"content": "You could install dtc,sudo apt install device-tree-compilerand then runCode:cd ~dtc -I dtb -O dts /boot/overlays/mhs35.dtbo mhs35.dtssed -i -e 's|^\\([ \\t]*\\)rotate *= *<[^>]*>|\\1rotate = <0>|g' mhs35.dtsdtc -I dts -O dtb mhs35.dts mhs35.dtbosudo cp -f mhs35.dtbo /boot/overlays/mhs35.dtbosudo cp -f mhs35.dtbo /boot/overlays/mhs35-overlay.dtbsudo chmod u=rw,go=r /boot/overlays/mhs35*.dtb*to decompile the device tree overlay, change the rotation parameter, recompile it, and save it back. Reboot. If the display orientation changes, but isn't correct, runCode:cd ~sed -i -e 's|^\\([ \\t]*\\)rotate *= *<[^>]*>|\\1rotate = <180>|g' mhs35.dtsdtc -I dts -O dtb mhs35.dts mhs35.dtbosudo cp -f mhs35.dtbo /boot/overlays/mhs35.dtbosudo cp -f mhs35.dtbo /boot/overlays/mhs35-overlay.dtbsudo chmod u=rw,go=r /boot/overlays/mhs35*.dtb*and reboot.In both cases, thesedcommand edits therotatevalue inmhs35.dts. You can usenano mhs35.dtsinstead, if you don't trust my regular expression. :|If this does not fix it either, then deeper digging is needed. Listing the files you have in/boot/overlays/would be a good start for that.Edited to add: Also, if you run a 5.4 or newer kernel, then you might be using TINYDRM_ILI9486 (ili9486) DRM driver instead (which is a much better solution anyway). So, do check your kernel version (uname -rorcat /proc/version), too."
},
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 05, 2024, 06:37:33 pm",
"content": "Thanks for the replyQuote from: Nominal Animal on May 05, 2024, 05:26:51 pmAfter this line I get:Code:Usage: dtc <input file>Options: -[qI:O:o:V:d:R:S:p:a:fb:i:H:sW:E:@AThv]-q, --quietQuiet: -q suppress warnings, -qq errors, -qqq all-I, --in-format <arg>Input formats are:dts - device tree source textdtb - device tree blobfs - /proc/device-tree style directory-o, --out <arg>Output file-O, --out-format <arg>Output formats are:dts - device tree source textdtb - device tree blobyaml - device tree encoded as YAMLasm - assembler source-V, --out-version <arg>Blob version to produce, defaults to 17 (for dtb and asm output)-d, --out-dependency <arg>Output dependency file-R, --reserve <arg>Make space for <number> reserve map entries (for dtb and asm output)-S, --space <arg>Make the blob at least <bytes> long (extra space)-p, --pad <arg>Add padding to the blob of <bytes> long (extra space)-a, --align <arg>Make the blob align to the <bytes> (extra space)-b, --boot-cpu <arg>Set the physical boot cpu-f, --forceTry to produce output even if the input tree has errors-i, --include <arg>Add a path to search for include files-s, --sortSort nodes and properties before outputting (useful for comparing trees)-H, --phandle <arg>Valid phandle formats are:legacy - \"linux,phandle\" properties onlyepapr - \"phandle\" properties onlyboth - Both \"linux,phandle\" and \"phandle\" properties-W, --warning <arg>Enable/disable warnings (prefix with \"no-\")-E, --error <arg>Enable/disable errors (prefix with \"no-\")-@, --symbolsEnable generation of symbols-A, --auto-aliasEnable auto-alias of labels-T, --annotateAnnotate output .dts with input source file and line (-T -T for more details)-h, --helpPrint this help and exit-v, --versionPrint version and exitError: missing fileseven though the filemhs35.dtbois in the Overlays folder, and has the appropriate access permissions, so it should be possible for the dtc command to process it...Code:ls /boot/overlaysact-led.dtboadafruit18.dtboadafruit-st7735r.dtboadau1977-adc.dtboadau7002-simple.dtboads1015.dtboads1115.dtboads7846.dtboadv7282m.dtboadv728x-m.dtboakkordion-iqdacplus.dtboallo-boss2-dac-audio.dtboallo-boss-dac-pcm512x-audio.dtboallo-digione.dtboallo-katana-dac-audio.dtboallo-piano-dac-pcm512x-audio.dtboallo-piano-dac-plus-pcm512x-audio.dtboanyspi.dtboapds9960.dtboapplepi-dac.dtboarducam-64mp.dtboarducam-pivariety.dtboat86rf233.dtboaudioinjector-addons.dtboaudioinjector-bare-i2s.dtboaudioinjector-isolated-soundcard.dtboaudioinjector-ultra.dtboaudioinjector-wm8731-audio.dtboaudiosense-pi.dtboaudremap.dtbobalena-fin.dtbobcm2712d0.dtbocamera-mux-2port.dtbocamera-mux-4port.dtbocap1106.dtbochipdip-dac.dtbocirrus-wm5102.dtbocma.dtbocm-swap-i2c0.dtbocrystalfontz-cfa050_pi_m.dtbocutiepi-panel.dtbodacberry400.dtbodht11.dtbodionaudio-kiwi.dtbodionaudio-loco.dtbodionaudio-loco-v2.dtbodisable-bt.dtbodisable-bt-pi5.dtbodisable-emmc2.dtbodisable-wifi.dtbodisable-wifi-pi5.dtbodpi18cpadhi.dtbodpi18.dtbodpi24.dtbodraws.dtbodwc2.dtbodwc-otg.dtboedt-ft5406.dtboenc28j60.dtboenc28j60-spi2.dtboexc3000.dtbofbtft.dtbofe-pi-audio.dtbofsm-demo.dtbogc9a01.dtboghost-amp.dtbogoodix.dtbogooglevoicehat-soundcard.dtbogpio-charger.dtbogpio-fan.dtbogpio-hog.dtbogpio-ir.dtbogpio-ir-tx.dtbogpio-key.dtbogpio-led.dtbogpio-no-bank0-irq.dtbogpio-no-irq.dtbogpio-poweroff.dtbogpio-shutdown.dtbohat_map.dtbhd44780-lcd.dtbohdmi-backlight-hwhack-gpio.dtbohifiberry-amp100.dtbohifiberry-amp3.dtbohifiberry-amp4pro.dtbohifiberry-amp.dtbohifiberry-dac8x.dtbohifiberry-dac.dtbohifiberry-dacplusadc.dtbohifiberry-dacplusadcpro.dtbohifiberry-dacplusdsp.dtbohifiberry-dacplus.dtbohifiberry-dacplushd.dtbohifiberry-digi.dtbohifiberry-digi-pro.dtbohighperi.dtbohy28a.dtbohy28b-2017.dtbohy28b.dtboi2c0.dtboi2c0-pi5.dtboi2c1.dtboi2c1-pi5.dtboi2c2-pi5.dtboi2c3.dtboi2c3-pi5.dtboi2c4.dtboi2c5.dtboi2c6.dtboi2c-bcm2708.dtboi2c-fan.dtboi2c-gpio.dtboi2c-mux.dtboi2c-pwm-pca9685a.dtboi2c-rtc.dtboi2c-rtc-gpio.dtboi2c-sensor.dtboi2s-dac.dtboi2s-gpio28-31.dtboilitek251x.dtboimx219.dtboimx258.dtboimx290.dtboimx296.dtboimx327.dtboimx378.dtboimx462.dtboimx477.dtboimx519.dtboimx708.dtbointerludeaudio-analog.dtbointerludeaudio-digital.dtboiqaudio-codec.dtboiqaudio-dac.dtboiqaudio-dacplus.dtboiqaudio-digi-wm8804-audio.dtboiqs550.dtboirs1125.dtboi-sabre-q2m.dtbojedec-spi-nor.dtbojustboom-both.dtbojustboom-dac.dtbojustboom-digi.dtboltc294x.dtbomax98357a.dtbomaxtherm.dtbombed-dac.dtbomcp23017.dtbomcp23s17.dtbomcp2515-can0.dtbomcp2515-can1.dtbomcp2515.dtbomcp251xfd.dtbomcp3008.dtbomcp3202.dtbomcp342x.dtbomedia-center.dtbomerus-amp.dtbomhs35.dtbomhs35.dtsmhs35-overlay.dtbmidi-uart0.dtbomidi-uart0-pi5.dtbomidi-uart1.dtbomidi-uart1-pi5.dtbomidi-uart2.dtbomidi-uart2-pi5.dtbomidi-uart3.dtbomidi-uart3-pi5.dtbomidi-uart4.dtbomidi-uart4-pi5.dtbomidi-uart5.dtbominipitft13.dtbominiuart-bt.dtbomipi-dbi-spi.dtbomlx90640.dtbommc.dtbomz61581.dtboov2311.dtboov5647.dtboov64a40.dtboov7251.dtboov9281.dtbooverlay_map.dtbpapirus.dtbopca953x.dtbopcf857x.dtbopcie-32bit-dma.dtbopcie-32bit-dma-pi5.dtbopibell.dtbopifacedigital.dtbopifi-40.dtbopifi-dac-hd.dtbopifi-dac-zero.dtbopifi-mini-210.dtbopiglow.dtbopiscreen2r.dtbopiscreen.dtbopisound.dtbopisound-pi5.dtbopitft22.dtbopitft28-capacitive.dtbopitft28-resistive.dtbopitft35-resistive.dtbopps-gpio.dtboproto-codec.dtbopwm1.dtbopwm-2chan.dtbopwm.dtbopwm-ir-tx.dtboqca7000.dtboqca7000-uart0.dtboramoops.dtboramoops-pi4.dtboREADMErotary-encoder.dtborpi-backlight.dtborpi-codeczero.dtborpi-dacplus.dtborpi-dacpro.dtborpi-digiampplus.dtborpi-ft5406.dtborpi-poe.dtborpi-poe-plus.dtborpi-sense.dtborpi-sense-v2.dtborpi-tv.dtborra-digidac1-wm8741-audio.dtbosainsmart18.dtbosc16is750-i2c.dtbosc16is752-i2c.dtbosc16is752-spi0.dtbosc16is752-spi1.dtbosdhost.dtbosdio.dtbosdio-pi5.dtboseeed-can-fd-hat-v1.dtboseeed-can-fd-hat-v2.dtbosh1106-spi.dtbosi446x-spi0.dtbosmi-dev.dtbosmi.dtbosmi-nand.dtbospi0-0cs.dtbospi0-1cs.dtbospi0-2cs.dtbospi1-1cs.dtbospi1-2cs.dtbospi1-3cs.dtbospi2-1cs.dtbospi2-1cs-pi5.dtbospi2-2cs.dtbospi2-2cs-pi5.dtbospi2-3cs.dtbospi3-1cs.dtbospi3-1cs-pi5.dtbospi3-2cs.dtbospi3-2cs-pi5.dtbospi4-1cs.dtbospi4-2cs.dtbospi5-1cs.dtbospi5-1cs-pi5.dtbospi5-2cs.dtbospi5-2cs-pi5.dtbospi6-1cs.dtbospi6-2cs.dtbospi-gpio35-39.dtbospi-gpio40-45.dtbospi-rtc.dtbossd1306.dtbossd1306-spi.dtbossd1331-spi.dtbossd1351-spi.dtbosuperaudioboard.dtbosx150x.dtbotc358743-audio.dtbotc358743.dtbotinylcd35.dtbotpm-slb9670.dtbotpm-slb9673.dtbouart0.dtbouart0-pi5.dtbouart1.dtbouart1-pi5.dtbouart2.dtbouart2-pi5.dtbouart3.dtbouart3-pi5.dtbouart4.dtbouart4-pi5.dtbouart5.dtboudrc.dtbougreen-dabboard.dtboupstream.dtboupstream-pi4.dtbovc4-fkms-v3d.dtbovc4-fkms-v3d-pi4.dtbovc4-kms-dpi-generic.dtbovc4-kms-dpi-hyperpixel2r.dtbovc4-kms-dpi-hyperpixel4.dtbovc4-kms-dpi-hyperpixel4sq.dtbovc4-kms-dpi-panel.dtbovc4-kms-dsi-7inch.dtbovc4-kms-dsi-generic.dtbovc4-kms-dsi-lt070me05000.dtbovc4-kms-dsi-lt070me05000-v2.dtbovc4-kms-dsi-waveshare-panel.dtbovc4-kms-kippah-7inch.dtbovc4-kms-v3d.dtbovc4-kms-v3d-pi4.dtbovc4-kms-v3d-pi5.dtbovc4-kms-vga666.dtbovga666.dtbovl805.dtbow1-gpio.dtbow1-gpio-pi5.dtbow1-gpio-pullup.dtbow1-gpio-pullup-pi5.dtbow5500.dtbowatterott-display.dtbowaveshare-can-fd-hat-mode-a.dtbowaveshare-can-fd-hat-mode-b.dtbowittypi.dtbowm8960-soundcard.dtboEDIT:Quote from: Nominal Animal on May 05, 2024, 05:26:51 pmThe kernel is supposedly 6.6.20. I will look for this TINYDRM_ILI9486 (ili9486) DRM driver."
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 05, 2024, 08:03:06 pm",
"content": "config.txt, cmdline.txt and overlays folder are moved from/boot/to/boot/firmware/with some update for 6.* kernel.So, the proper way is to edit/boot/firmware/config.txtinstead of/boot/config.txtif you edit /boot/config.txt it won't have effect.Did you take this into account?"
},
{
"post_id": "",
"author": "bodzio_stawski",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 05, 2024, 09:31:49 pm",
"content": "Quote from: radiolistener on May 05, 2024, 08:03:06 pmI didn't take this into account at all, I admit. When I came to the conclusion that terminal commands change the values in the /boot/config.txt file, I had no idea that this second file (/boot/firmware/config.txt) exists. Thank you very much, this solved the problem and now the rotation finally works. Thanks also to you, Nominal Animal, because you gave me a lot of new content along the way, also devoting your time. Thank you gentlemen!"
}
] |
2025-10-17T16:36:10.224905
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(repair)-current-reading-error-with-dsn-vc288-(100v-10a-voltmeter-ammeter)/
|
[Repair] Current reading error with DSN-VC288 (100V 10A Voltmeter Ammeter) - Page 1
|
[
{
"post_id": "",
"author": "danon.spy",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 18, 2018, 12:02:54 pm",
"content": "Hi DIYer,I have come across this issue. When I tried to make a power supply using some cheap DC to DC converter and a volt+amp meter, the current meter show an error as in the pictures. It show stable ~15.5A even with or without load. I don't know what have I didWhen I shorted the little current shunt with the LM358 opamp (pin 2 or 3 or 4), it seems to fix the issue. But I don't know if I permanently do that, would it destroy that meter? Will it have any negative effect?Images (click on image for original size):"
},
{
"post_id": "",
"author": "BrankoMN",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "March 23, 2018, 08:31:17 pm",
"content": "https://www.ittsb.eu/forum/index.php?topic=1351.0"
},
{
"post_id": "",
"author": "danon.spy",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 24, 2018, 09:58:48 am",
"content": "Quote from: BrankoMN on March 23, 2018, 08:31:17 pmThank you so much for that link.I am reading this and test on my meter with the RESET trick, will update for the result."
},
{
"post_id": "",
"author": "jorgemef",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 19, 2022, 12:14:20 am",
"content": "After some fighting with a latest one from AliExpress I concluded:Best linearity is achieved by using external supply.If using same supply leave ground from voltage plug floating else will add a lot offset impossible to compensate with potenciometer.The best linearity I achieved was by incrementally regulating the potenciometer and reset the module to compensate offset for potenciometer setting unloaded. I used same power supply so with 10ma I read 8ma and with 1,5A I read 1,53A. With external supply I achieved 10mA as 10mA and 5A as 5,01A.I opted for same supply as is enough for my needs and didn't wanted to buy another transformer just to power it up as I am using two independent units in a same power supply to have independent rails. Have small switching PSU Wich I could use but they introduce EMI in the output through the amperimeter."
},
{
"post_id": "",
"author": "jorgemef",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 22, 2022, 04:48:04 pm",
"content": "Hello.Any bether unit that fits same layout or suggested seller that sell a good version of this meter?Unfortunately one of my units broke during reset. Not sure if is because I reseted with it on, but had done it before without problems. This time microcontroller and LDO let magic smoke out.I was powering them with 28V. Maybe was too much.Will look for a new unit to fit to my almost finished dual rail power supply. If I can find something better than my crippled version will go for it.Cheers,Jorge"
},
{
"post_id": "",
"author": "BrankoMN",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "October 22, 2022, 08:24:19 pm",
"content": "Try thishttps://www.aliexpress.com/item/1005003786622190.html?spm=a2g0o.order_list.0.0.21ef1802VVJUFkand read carefully product description. Here is a description of how to set it uphttps://youtu.be/NxnhyCE43Vc. I bought one and it works great."
},
{
"post_id": "",
"author": "xavier60",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2022, 10:52:57 am",
"content": "I wish the display refresh was really 300ms as advertised instead of really being 1000ms.Those 4 digit meters have auto-zeroing on the current meter, so the reading is very stable."
},
{
"post_id": "",
"author": "smd_hunter",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "October 24, 2022, 02:18:12 pm",
"content": "Quote from: jorgemef on October 19, 2022, 12:14:20 amThanks for the idea Jorge! I have two DC-DC source modules with segment display to see voltage and current, one of them has a lm358, the other one does not. The one with the op-amp differs the current as it happens to the OP. When I get home I will do some tests."
}
] |
2025-10-17T17:04:04.790316
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(review-request)-micro-sd-card-schematic/
|
[Review Request] micro SD card schematic - Page 1
|
[
{
"post_id": "",
"author": "kuelezav",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 15, 2024, 10:04:43 pm",
"content": "Hello everyone. I was hoping to get some feedback on my schematic for an SD card socket. Will this design work? My aim is record sensor data (accelerometer, temperature, pressure, etc.) and store onto an sd card using SPI communication with an ESP32. Would this design work? Is there anything I can do to improve it? Any help would be greatly appreciated.Thanks.https://1drv.ms/i/s!Asdy5Rhffb67tCDIX1rHm1HR9td0?e=N3WkeDhttps://1drv.ms/i/s!Asdy5Rhffb67tB8gssjrHJdLJW0W?e=35cFmd"
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 15, 2024, 10:45:55 pm",
"content": "Why are there two schematics?Just place the whole thing on one sheet and draw the wires."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 15, 2024, 11:03:19 pm",
"content": "Your GPIO12 and CLK of the card is connected directly to VCC."
},
{
"post_id": "",
"author": "kuelezav",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 15, 2024, 11:08:36 pm",
"content": "https://1drv.ms/i/s!Asdy5Rhffb67tCEufFxDQUo24-m3?e=ljAF20How about this one? For clock, is it better to have it connected only to the GPIO on the ESP32 or should I add a pull-up resistor to CLK?"
},
{
"post_id": "",
"author": "kuelezav",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 15, 2024, 11:15:45 pm",
"content": "They're both on the same schematic. I just screenshot these two."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 15, 2024, 11:21:13 pm",
"content": "Direct connection should be fine. Or place a resistor and not populate it if it causes issues.A better idea is to find a working design and copy it."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 15, 2024, 11:25:20 pm",
"content": "Quote from: kuelezav on December 15, 2024, 11:15:45 pmSo what's your expectation? If it's screenshots from a half-finished design, it's futile.Do the homework and THEN ask for a review."
},
{
"post_id": "",
"author": "kuelezav",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 15, 2024, 11:32:28 pm",
"content": "https://1drv.ms/i/s!Asdy5Rhffb67tCJRn_Itcs7zvmNM?e=bZr8OQHow about this? Is this what you were referring to?"
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 15, 2024, 11:36:40 pm",
"content": "Dunno. Needs a login."
},
{
"post_id": "",
"author": "kuelezav",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 15, 2024, 11:41:47 pm",
"content": "Sorry about that. Are you able to see this one?"
},
{
"post_id": "",
"author": "kuelezav",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 15, 2024, 11:50:48 pm",
"content": "Apologies. The link may not be accessible. Are you able to see the attached image?"
}
] |
2025-10-17T16:26:12.494873
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(review-request)-stm32-breakout-board/
|
(Review request) STM32 Breakout board - Page 1
|
[
{
"post_id": "",
"author": "Fcolor04",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 24, 2023, 02:38:22 pm",
"content": "Hello, I've recently been listening to all the do's and dont's of pcb design and so I want to ask for a pcb review of my arduino sized STM32 bluepill redesign, I used two ldo's for higher current capability but I didnt put many power output pins just yet because I want to get signals right first, do you think its gonna have EMI issues or ground loop issues? What would you suggest I take a look at/improve/redo?"
},
{
"post_id": "",
"author": "ArdWar",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 24, 2023, 03:56:03 pm",
"content": "Quote from: Fcolor04 on June 24, 2023, 02:38:22 pmThat's not how you parallel LDO, you can't just connect two together.Use ballast resistorIf you want to improve thermals, get LDO where the tab is GND. There are a lot of them available. I personally never a fan of Vout on tab design...Do you really plan to draw the full 3A out of it? When dissipation exceeds 3W it might be time to start considering buck regulator instead.I see there are a lot of places where your traces don't really need to switch layers, but that's not critical I guess.ED: A lot of your traces seems to be not actually connect to header pads. Don't you get DRC error? Where are the ratsnests?"
},
{
"post_id": "",
"author": "Fcolor04",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 24, 2023, 04:23:49 pm",
"content": "I'll look for other LDO, I meant 1.6A rating when combined, headers aren't connected yet because I dont want to change schemating a dozen of times if someone tells me that I should have more ground pins in between signals for example. Regarding \"signals changing layers when they don't have to\", I did that to preserve wide ground plane interconnections, with signal line going almost across the board it looked like the ground plane would split across with 1-2mm connection which doesn't sound like its best practise"
},
{
"post_id": "",
"author": "DavidAlfa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 24, 2023, 09:29:36 pm",
"content": "EMI issues? That's only for commercial or extremely sensitive applications - A breadboard powered for USB is nothing special.Yeah, the inventor to the LDOs with Vin in the tab should get executed, just why!I recently tried to find a decent SOT89 LDO, high noise rejection, low drop, >500mA...90% of them had power in the tab! The rest were just to expensive so I finally gave up.Not a bad layout, but add via stitching between ground planes!Paralleling LDOs is not good, they never have 100% voltage output so one might work a lot harder than the other.If powering high current devices like leds, motors, better to use a switching converter module.But keep a LDO to power the stm32 and analog stuff, you don't want noisy rails there!"
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2023, 09:23:51 am",
"content": "Quote from: Fcolor04 on June 24, 2023, 04:23:49 pmYou’ve got tons and tons of layer changes that make zero sense. Like all the top-layer connections to the left side header: why not just leave them on the bottom layer?Or the bundles of layer changes at the bottom, which exist only to get around some components that have no need to be in that exact spot (and almost certainly would benefit from being somewhere else).Or just above the MCU, where there’s a knot of vias and traces that could almost certainly be simplified.It’s not that it won’t work. It’s just needlessly complicated. And all those unnecessary via jumps take up space, taking away from the ground planes."
},
{
"post_id": "",
"author": "Fcolor04",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 25, 2023, 07:46:57 pm",
"content": "I've redone left connector tracks, tried to remove as many vias as I can, removed other LDO, its gonna cause more issues than necessary, I think its production ready hopefully I didn't miss anything this time"
},
{
"post_id": "",
"author": "DavidAlfa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2023, 09:27:44 pm",
"content": "Siggestion: avoid smaller parts than 0603 if soldering by hand!Also these smd electrolytics are a bit messy to get done, I'd put through holes in the said case.Still, that board can be made much smaller, specially in the LDO side"
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 25, 2023, 10:00:52 pm",
"content": "The SWD connector is in a very unfortunate location.If you move that connector, then you can route all the I/O to the first 10 pins to the left side connector on a single layer, and keep the other layer empty except for the GND plane.I also don't like running the reset track under the uC in the way you did. I prefer to at least have a local GND zone directly under the microcontroller, which connects all GND pins of the uC together."
},
{
"post_id": "",
"author": "Fcolor04",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 27, 2023, 12:25:41 am",
"content": "Thanks for all the suggestions, here's V3 of my design, it shrunk by 20%!!! by moving reset and analog voltage supply a bit also the 2 solid ground planes under uC should be much better than the original, any other tips?"
},
{
"post_id": "",
"author": "DavidAlfa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 27, 2023, 01:28:28 am",
"content": "You improved really fast , much better!Though you made a little ooops at pin 20, fix that track!What USB-C connector is that? Looks pretty awkard to me!Nevermind:https://jlcpcb.com/partdetail/HOOYA-USB306B/C309343"
},
{
"post_id": "",
"author": "ArdWar",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 27, 2023, 01:37:33 am",
"content": "Beware with the two huge caps in the VBUS. I don't remember exactly but I *think* there's guideline on how much inrush current and capacitance you can put on VBUS. A maximum of 10uF can be directly connected without inrush limiter IIRC.You probably don't need (or want) to make your board USB certified, but conforming to standards and best practices as much as possible is still a good idea. You probably don't need to limit to such extent, but definitely don't put two 220uF caps on it 😅"
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 28, 2023, 04:03:58 pm",
"content": "It does indeed already look a lot better. Some more ideas:Big ceramic capacitors on the output of an LM1117 can lead to instability. (I have not checked the \"LD\" version datasheet).I agree with the big buffer caps. These lead to very high peak currents when the connector is inserted, and this leads to sparking and connnector wear.Make the interruptuions from tracks on the blue layer shorter to improve the GND plane. In general when you have to interrupt the GND plane with tracks, add some via stitching if there are tracks on the other side to provide a return path for the sinals through the GND plane. In this situation it does not matter much because there is only one GND pin for the connectors on the right side (hint: adding more GND pins would be an EMC improvement)Move the capacitor in the top left corner of the microcontroller a bit so the GND plane has a solid connecton.There are some quite large area's on the red layer which are only connected to GND in a single corner. Such area's can (and will) act as antennas which can both pick up and transmit noise. You can add some via stitching to prevent this.Add one (or two) stitching via's to each GND pin of each capactor, to directly connect it to the GND layer on the bottom of the PCB.KiCad has a \"Symbol\" library which also has kicad logo's. It's always nice to see more KiCad logo'sI count around 20 DRC violations (arrows). What are they for? Are any of them important? (You can disable them in DRC if you have verified they are not important"
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 01, 2023, 01:51:03 pm",
"content": "Soooo much better in the revised version. Well done, Fcolor04.It’s good practice to not route any traces underneath your crystal. You’ve got enough space to easily make this change.Regarding LM1117 stability with ceramic caps: rather than changing the layout, I would simply find a pin-compatible alternative that is specified to be stable with ceramic input and output caps. For example, the LDL1117 from ST. Its performance (as far as noise rejection) is overkill for a microcontroller, but it’s still only about €1 and is expressly designed to work with ceramic caps. (I used it on the last MCU board I made.) Your regulator layout is physically nice and tight as it should be.I would just add more vias to ground, just like Doctorandus_P said. Put one or two next to each ground pad of components (especially ones with higher current, like power supply caps, where you may even want to add more), as close as possible. I would add a bunch of vias to the regulator ground, to ensure it’s got a nice, low-impedance path to ground. And since you’re not running out of space, just sprinkle them all over the place as via stitching. (I think kicad has a function for that, either built in or as a plug-in.) Just do that when you’re otherwise done."
}
] |
2025-10-17T16:52:12.909776
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(rf-basics)-mc60e/
|
RF basics - Page 1
|
[
{
"post_id": "",
"author": "papamoscas",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 17, 2018, 10:42:06 am",
"content": "Hi,I'm a beginner in the world of the PCB's and of RF. I need your help and your knowledge.I want to make a PCB with the Quectel MC60E with the two SMA connectors, one for GSM signal, other for the GPS/GLONASS. For the BLE I want to put one antenna on the board like A5839 Antenova (http://www.antenova-m2m.com/wp-content/uploads/2016/01/Rufa-A5837-A5887-PS-1-2.pdf).I already did my research but I'm a bit confused, I think I only need to take care of the 50 Ohm pad from the MC60E to SMA connector.My questions are :- I only need to take care of the impedance matching? What is the best procedure to do that?-What are the most important things to have a PCB without EMI problems? The PCB will have more components like sensors for example...Thanks in advance"
}
] |
2025-10-17T18:29:09.200289
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(rfc-on-yt-video)-_how-vrms-work_-mosfets-pwm-phases-and-stuff/
|
[RFC on YT Video] "How VRMs work" - DaveCAD, MOSFETs, PWM, Phases, …and stuff - Page 1
|
[
{
"post_id": "",
"author": "faekjarz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 29, 2016, 01:21:58 am",
"content": "Hey there!I've found this video on YT ?? and i like it. Since, according to Louis Rossmann (https://www.youtube.com/user/rossmanngroup), this here forum sometimes tends to be overly critical, i'd like to request some of that over-criticallity.The dude didn't elaborate on the (purpose of the) caps …those are for smoothing the ripple of the phases, right?"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2016, 03:46:55 am",
"content": "A half an hour? Meh...If you mean bypass caps, then yes, smoothing input and output voltages.Tim"
}
] |
2025-10-17T19:09:31.239273
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(rigol)-oscilloscope-ground-clip-leads/
|
[Rigol] Oscilloscope ground clip leads - Page 1
|
[
{
"post_id": "",
"author": "int2str",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 06, 2015, 05:51:13 am",
"content": "Just got a Rigol DS1054Z. I really don't like the alligator clips on the ground leads.Does anybody make leads with spring loaded hooks?Also, are the ground clips Rigol specific or do other manufacturers use the same diameter spade attachment point?"
},
{
"post_id": "",
"author": "Smokey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 06, 2015, 06:19:51 am",
"content": "Funny. I said the same thing.I had a set of 4 cheap Chinese 100MHz probes I got for like 15 bucks off ebay that I had already replaced the alligator clips for EZHooks. I just desoldered the alligator clips and used some good Pomona EZhooks. Those probes use the same type of ground wire as the new DS1054Z, so I just swapped them out. If I want alligator clips for something, I can just swap them back.http://www.ebay.com/itm/Two-P6100-DC-100MHZ-Oscilloscope-Scope-Clip-Probe-100MHz-For-Tektronix-HP-SY-/331378782364?pt=LH_DefaultDomain_0&hash=item4d27b6f09c"
}
] |
2025-10-17T19:43:31.554305
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(schematic-review)-semi-automatic-switching-grid-ecoflow/
|
[Schematic Review] Semi-automatic switching: Grid - EcoFlow - Page 1
|
[
{
"post_id": "",
"author": "glebkooo",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 21, 2024, 09:19:52 am",
"content": "Hello.Please help review the following idea / schematic. The main questions - is it actually safe.What I want to achieve is to charge EcoFlow Delta 2 when the household is connected to grid, and power the household from EcoFlow's inverter during blackouts.I have a 2 pole mains breaker separating the apartment from grid. So when grid goes off, I turn the breaker off, then connect EcoFlow's inverter output directly to the wall socket and turn it on. When power from grid becomes available again, I turn inverter off, unplug it's output from wall socket, plug the EcoFlow's \"charger\" cable to wall socket, and, finally turn on the mains breaker.I want to somehow automate this plugging and unplugging. I am not allowed to change the wiring in the apartment, because it is rented. So I cannot use Automatic Transfer Switch there.The idea is to use 2NC-2NO 25A Contactor driven by a Controller (Isolated AC-DC converter + MCU + Relay).When Controller is powered off, the EcoFlow charges from mains thru the normally closed contacts.When I turn on the EcoFlow's inverter it starts powering the Controller. If Controller detects there is no mains (using Optocoupler) - it turns on the coil of contactor, and the latter one disconnects EcoFlow's charger and connects the household mains to the inverter. Of course, I need to switch mains breaker off before that."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 23, 2024, 11:39:48 pm",
"content": "Below is a link that summarizes the National Electric Code in the US for such circuits. What you have looks safe in general. You might want to get your design figured out in detail and do a failure analysis. Allow any component to fail and see what the effect is. If there is a single fault that can cause an unsafe condition, it should be eliminated. For example, what would happen if the opto that sense the grid being out didn't operate? etc, etc.Be very careful, a lot of electrocutions have been caused with switchover circuits. Its a special danger to linemen working outside your house if you are not isolated from the grid. You should be an \"island\" when in an emergency. I see you're in Ukraine and circumstance might be difficult, it likely won't be you that gets hurt, it might be an innocent family member. Tag out switches and breakers very explicitly and keep people out of them.https://windsorlocksct.org/wp-content/uploads/2020/09/generator_requirements.pdfYou can read the requirements above- it looks like you understand the problem.The ampacity of the wiring has to be chosen and circuits must be fused properly- generally only certain loads are powered by backup power. Circuits should (but don't have to) operate automatically. Usually, emergency loads are segregated into a seperate box that is powered by the aux power source.There has to be a positive means to permanently isolate the generator from the power grid. This is usually a removable disconnect block.Also- there may be a loop in your system where the inverter could be running and charging its own battery unless the changeover switch won't allow this - is this possible- it shouldn't be."
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 24, 2024, 01:49:46 am",
"content": "Quoteplease dont tell me your using a plug to feed power into a socket,such devices are known as widow makers for a very good resaon"
},
{
"post_id": "",
"author": "leham",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 24, 2024, 03:04:23 am",
"content": "Doesn't the ecoflow have a UPS function.Why not just use that and put the important stuff you'll need in a blackout on its output.The average apartment size there is 57 sqm, I'd take the mess of cables (that could be tidy) over back feeding your apartment and possibly introducing hazards to you or someone else"
},
{
"post_id": "",
"author": "glebkooo",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 24, 2024, 08:02:09 pm",
"content": "Thank you for detailed answers!The first thing I am planning to do before implementing that, is to consult an electrician, maybe he would propose a better and safer solution."
}
] |
2025-10-17T16:30:06.603382
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(schematic-review-request)-fpga-power-circuit/
|
[Schematic Review Request] FPGA Power Circuit - Page 1
|
[
{
"post_id": "",
"author": "HasanSyr",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "March 12, 2025, 06:39:55 pm",
"content": "FPGA Power Circuit for my development board built around/for a SOM."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 13, 2025, 02:57:27 pm",
"content": "The one glaring problem that I see is that you can't buck a 5v nominal signal from USB Vbus to 5v- there is no headroom. Though the 62130 can run at 100% duty cycle, you'll still have IR losses through the internal FET and the inductor resistance. The HS FET has a resistance of 90 mohm so with a 2 amp load, you drop 180 mV plus the inductor IR drop. USB rails are often at or below 5v when loaded. Can you use Vbus without a buck for 5v and use the buck only on 3.3V. All the curves in the data sheet show a volt or more of headroom.As far as the rest, it look ok. I assume you used Webbench. Also follow the layout guidelines- these are very high frequency switchers and need a tight layout. Section 11 in the DS is very good for layout details."
},
{
"post_id": "",
"author": "HasanSyr",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "March 13, 2025, 05:36:09 pm",
"content": "Quote from: jwet on March 13, 2025, 02:57:27 pmSomeone has mentioned the same point and recommended using Buck/Boost. Im thinking of using TPS63020DSJR, if VBUS is below/above 5V it can adjust I think."
}
] |
2025-10-17T16:21:51.894232
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(schematic-review-request)-solar-powered-macropad-review-request/
|
[Schematic Review Request] Solar Powered macropad review request - Page 1
|
[
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 04, 2025, 04:40:16 am",
"content": "Hi! I haven't designed any circuits in about a year, and I'm getting started again, I barely remember anything...i was wondering if any of you could go over my schematic and give me advice or see if there's potential issues? I'm starting again after a long time so I'm sure the schematic is full of flaws...(PS, the U1 is a nice!view clone I got off AliExpress, it'll be changed to a nrf54l15 module so that's why I have a separate TP4056 circuit and a separate 3.3v, I might switch it to a modern and safer alternative with built-in safety features such as a time, but for a first attempt, it's simpler and easierI'll not solder those components/leave them empty depending on what I do, Or maybe if this revision looks good I'll just do it now and save myself the trouble.Thanks! I'll clean it up once it's approved and make it look neater."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2025, 04:52:43 am",
"content": "Question, if you don't mind: are you a woman?I ask because of your user ID, and also because there are so few women here, so it'd be an interesting data point.You are not, of course, required to answer this ..."
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 04, 2025, 05:11:00 am",
"content": "Quote from: Analog Kid on April 04, 2025, 04:52:43 amYeah I am.I do electronics for fun, I am(was) a software engineer I've taken a huge break and I barely have any of my skills left, tho I'm sure I'll pick them back up quickly!I'm sure there's more of us behind less obvious usernames"
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2025, 05:19:27 am",
"content": "Quote from: AmeliaBuns on April 04, 2025, 05:11:00 amI hope so!"
},
{
"post_id": "",
"author": "bookaboo",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 04, 2025, 08:08:06 am",
"content": "At a glance I don't see any glaring errors.What part is U1?Is it a module with onboard debug/prog?One suggestion would be to breakout the 5x spare pins to a header and/or LEDs to help with firmware development."
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2025, 04:41:52 pm",
"content": "I believe Q1 - your power path mosfet - is oriented backwards. The body diode and the shottky should both be pointing to the load. Otherwise, the 5V supply could send current back through the body diode to the battery, which you don't want. See the orientation used here:http://ww1.microchip.com/downloads/en/AppNotes/01149c.pdf"
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 06, 2025, 05:44:37 am",
"content": "Quote from: Peabody on April 04, 2025, 04:41:52 pmWait, wouldn't the body diode pointing at the load (VCC which goes to regulator) mean that the mosfet is always conducting the battery to the load trough its body diode? but the VBUS charging the battery is a good catch, fire prevented! I should be more careful with Li-Po"
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 06, 2025, 05:54:36 am",
"content": "Quote from: bookaboo on April 04, 2025, 08:08:06 amIt was originally going to be a nice!nano clone because they're cheap, but I'm actually going to switch to a random NRF module instead. the nice nano sadly doesn't have it's SWDIO pins on the headers, so I have to unplug it and manually connect it each time I program, that's why it's not wired.I do think the spare pins and a debug LED is a good idea, I didn't add any as they consume too much power, but they'll only turn on for debugging I assume.I'm thinking of one of these ones:https://www.aliexpress.com/item/1005008589699276.htmlhttps://www.aliexpress.com/item/1005007218800421.html"
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 06, 2025, 01:54:45 pm",
"content": "Quote from: AmeliaBuns on April 06, 2025, 05:44:37 amNo, because when the main supply is connected, which is higher than the battery voltage, the body diode will be reverse biased, so no current will flow through it. And when it's not connected, the mosfet will turn on and the body diode will be bypassed so the battery can power the circuit. And if for any reason the mosfet doesn't turn on right away, the output can still be fed through the body diode.I know it seems backwards because you're used to seeing a mosfet used as a switch. But in this case, the body diode and the shottky make up a two-diode OR circuit, where the source with the higher voltage feeds the load, and both sources are protected from reverse current. Except that if the battery is the higher voltage, the mosfet turns on, which eliminates the voltage drop.Here's another link showing the same orientation:http://blog.zakkemble.net/a-lithium-battery-charger-with-load-sharing/"
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 07, 2025, 04:07:40 am",
"content": "Quote from: Peabody on April 06, 2025, 01:54:45 pmOh thank you I think I get it now! In a way, we're using it as a very efficient diode here.? We'd need a different circuit for a different battery voltage.I now realized by reading the document further that my new problem is the diode reverse leakage current... I'm gonna thoroughly read the document and the article you sent instead of skimming trough it for answers! I'll let you know once I change the circuit. I didn't know Schottky diodes are so leaky...EDIT: oh you can just BUY nice diodes... the more you knowPMEG10020AELP is really low leakage at 200nA reverse leakage.EDIT2: Oh wait it has a 0.7v forward voltage...I think I'm taking a nap before proceeding... I'm acting stupid."
},
{
"post_id": "",
"author": "rteodor",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 07, 2025, 04:58:09 am",
"content": "C12 (ENCODER_BTN) should be to GND I think.Not sure what you wanted to do with R1 in series with the button. Maybe button would be shorting the C, R1 would be gone and instead use internal pull-up resistor (like presumably with C10 and C11)."
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 07, 2025, 02:24:31 pm",
"content": "The reverse leakage current is particularly important in high current situations. The reverse current increases exponentially with temperature, so if the diode has been carrying all the current for a while, and has become a bit toasty, you'll get lots of leakage current when it changes state, at least until it cools down. And yes, it seems you can have low forward voltage, or low reverse leakage current, but not both.As discussed in the Zack Kemble post, the key to dealing with reverse current is the choice of the gate pulldown resistor. And I guess using a mosfet with a low threshold voltage will also help."
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 08, 2025, 05:25:40 am",
"content": "Quote from: rteodor on April 07, 2025, 04:58:09 amOh nice catch! it's meant to smooth the bouncing a bit. tho It's probably useless and I need to do hardware anyway? Specially for the encoder as it's changing faster.the R1 is for the RC filter but I haven't made stuff in so long it might be in the wrong place.I'm using the IC's internal pull-up."
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 08, 2025, 05:39:05 am",
"content": "Quote from: Peabody on April 07, 2025, 02:24:31 pmIt's only carrying 150ma max I think? it's to charge the battery.Also, I just realized, the path for the reverse current in this diode is to ground trough a 3.8Mohm resistor, meaning I don't have to worry about it? Although I just finished reading the article which made me realize, the MOFSET turning on is a bigger issue and likely at such a high resistance. I could split 3.8 into two resistors to create a voltage divider. to have both a reduced reverse current and not turn on the MOSFET. Would that work?What other solutions do I have to reduce the reverse voltage leakage? 150uA might not seem like a lot but it's a lot when your solar panel is only providing 100uA and the device consumes 30uA (in sleep/idle)The BQ24030 might be a solution, from what I understand, without VBUS or VAC it consumes 5uA which is accetable."
},
{
"post_id": "",
"author": "Jeroen3",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 08, 2025, 05:56:39 am",
"content": "Looks okay!C8 and C9 do not appear to be wired up.On U3, CELL and VDD are wired up like they are joined on the chip. I think the intention of CELL is to be asensewire. Typicaly these don't carry current to avoid drop. You could consider separating these. However, the MAX17048doesn't actually wire up CELL internally, so it would just be to avoid confusion of yourself in the future to make the intent more obvious.I would also try to make the schematic hint the pcb design of U2, eg C2 is a input capacitor that makes boost circuit, it should be placed closer to L1 imho to make it more obvious.However, I assume you're doing this for fun, so that could also be nitpicking on my end.If you were to commercialise it, there may need to be some more ESD diodes around the battery/solar inputs and the buttons (with possible current limit resistors)."
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 08, 2025, 06:31:13 am",
"content": "OK so I think I figured out some solutions, not sure which is best yet but I think choosing another charging IC is smarter!first of all, with a BAT20J diode, the discharge isn't high enough to lose sleep over or worry about. it's only 0.65uA which is almost nothing. the voltage drop at 100ma is 0.4v and at 1A it's 0.62v max, it's all within acceptable levels.there are 3 ics I found, two of which support power path integrated into them and consume only 4uA or 300nA which is close to negligible.the BQ25170 has only 350nA battery consumption when idle and the datasheet states:QuoteBQ25185 / BQ25188 have power path integrated into the IC and the datasheet states:– 4-μA in Battery Only mode.which isn't as low as the other one but it's still very acceptable."
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 08, 2025, 06:47:44 am",
"content": "Quote from: Jeroen3 on April 08, 2025, 05:56:39 amAll great tips, I am doing this for fun, but one day, I dream of making products to sell, so having those tips is handy, and I appreciate knowing which ones are mandatory for function and which ones are for commercialization as I'm taking it very slow! this way I can focus on getting anything that works, then optimizing it.VDD and CELL are wired up on the datasheet the same way, and the datasheet says it's just to sense the output voltage. I'm not sure what you mean by wiring it separately? for MAX17048 it say: \"Not internally connected\" anyways."
},
{
"post_id": "",
"author": "Jeroen3",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 08, 2025, 01:41:33 pm",
"content": "The intent of the CELL pin is to measure voltage of the cell. Not the cell plus voltage drop over pcb traces, because your device is taking current from the cell."
},
{
"post_id": "",
"author": "rteodor",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 08, 2025, 04:02:51 pm",
"content": "Quote from: AmeliaBuns on April 08, 2025, 05:25:40 amYou can drop R1 then and make button debouncing the same as for the encoder signals. I use 10nF with cca. 10Kohm pull-up and it works fine for both encoder and button."
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 08, 2025, 05:34:06 pm",
"content": "Quote from: AmeliaBuns on April 08, 2025, 05:39:05 amNot sure what you mean. The diode in question is D14 in the power path block. The reverse current could turn off the mosfet."
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 09, 2025, 05:17:55 am",
"content": "Quote from: Peabody on April 08, 2025, 05:34:06 pm'I was hoping for a lower gate voltage but it was a bad idea, as I mentioned in the previous comments, ZI am probably either going with the different IC or just switching to the diode I mentioned which has less reverse current."
},
{
"post_id": "",
"author": "AmeliaBuns",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 17, 2025, 06:52:48 pm",
"content": "I'm slowly giving up on the panels as they're 50cad for just extra battery life but I found this interesting article that might help others in similar situations. it's still great for the charging part. I'm opting to go with a charger with this feature built in myself however.https://hackaday.io/project/169422-iot-ups/log/203175-power-path-management-diode-or-ing"
}
] |
2025-10-17T16:19:56.832805
| 22
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(search)-datasheet-uaa3000/
|
[Search] Datasheet UAA3000 - Page 1
|
[
{
"post_id": "",
"author": "PinheadBE",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 16, 2019, 08:08:08 am",
"content": "That IC is a timer made by Valvo that can be directly used on mains power and used in an application circuit that has been around for quite some time now.Seehttp://electroniq.net/other-projects/uaa3000-timing-circuit-electronic-project.htmlI am looking for the datasheet for that little beastGoogle and usual datasheets websites return nothing.I have some of those IC's laying around and would like to see what I could use them for.So, if you have a datasheet for UAA3000, feel free to share.Thanks"
}
] |
2025-10-17T18:06:49.990899
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(solved)-unity-gain-differential-amplifier-not-working-as-expected/
|
[Solved] Unity Gain Differential Amplifier not working as expected - Page 1
|
[
{
"post_id": "",
"author": "king.oslo",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 13, 2012, 12:20:07 am",
"content": "Hello there,I made an Unity Gain Differential Amplifier circuit. This tutorial told me that Vout = V2-V1:http://www.electronics-tutorials.ws/opamp/opamp_5.htmlMy exact schematic is attached. R1-R4 are 22R3The problem is that Vout != V2-V1.I built it up using a Microchip MCP6041 on a bread board. This is what I found:Case 1:V2: =1.475VV1: =2.835VExpected Vout = -1.36VVout = 1.936VExpected Vout != Vout----------------------------------------Case 2:V2: = 0.982VV1: = 2.829VExpected Vout = -1.847Vout = 1.930Expected Vout != VoutThis is the datasheet for the opamp:http://ww1.microchip.com/downloads/en/DeviceDoc/21669c.pdfWhat have I missed?Thanks for your time.Kind regards,Marius"
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 13, 2012, 12:27:00 am",
"content": "Are you supplying the op amp with a dual rail supply? You have not said how you are powering it.You cannot expect to get a negative voltage out of an op amp unless you have a negative supply voltage fed into it."
},
{
"post_id": "",
"author": "king.oslo",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 13, 2012, 12:35:30 am",
"content": "Quote from: IanB on January 13, 2012, 12:27:00 amOpamp is powered by 5VDC to gnd. I think you just pointed out the problem."
},
{
"post_id": "",
"author": "slateraptor",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 13, 2012, 12:36:19 am",
"content": "Quote from: king.oslo on January 13, 2012, 12:20:07 amHere's your problem, viz. your lower rail is tied to ground, thus cannot produce negative voltage."
},
{
"post_id": "",
"author": "king.oslo",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 13, 2012, 12:39:23 am",
"content": "That's great.It says my opamp can only do 1.4V to 6.0.Does that mean that I power it like this: VDD = 6V, VSS = 0V. Then pull inverting input to 3VDC, and then measure Vout between Vout and 3VDC?1. That should work, right?2. Is this the traditional way to do it?Thanks.M"
},
{
"post_id": "",
"author": "slateraptor",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 13, 2012, 01:11:21 am",
"content": "Instead of tying R4 to ground, tie it to Vcc/2. Then measure your output with respect to Vcc/2. This is standard single-supply practice.EDIT: If you analyze the circuit assuming the op amp is ideal, you can easily see why this will work. I encourage you to give it a shot."
},
{
"post_id": "",
"author": "king.oslo",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 13, 2012, 02:24:05 am",
"content": "Thanks.Since I wasn't doing this, I was measuring Vout with respect to gnd, and tying R4 to gnd as well. What values was I actually measuring?Thank you for you time. Both of you.Kind regards,Marius"
},
{
"post_id": "",
"author": "slateraptor",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 13, 2012, 02:53:04 am",
"content": "Quote from: king.oslo on January 13, 2012, 02:24:05 amThe op amp's output wasn't within its normal operating region; you were effectively measuring junk."
},
{
"post_id": "",
"author": "king.oslo",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 13, 2012, 08:40:02 am",
"content": "Quote from: slateraptor on January 13, 2012, 02:53:04 amOk, thanks!M"
}
] |
2025-10-17T20:36:42.811082
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(solved)-what_s-the-q-of-this-circuit/
|
[Solved] What's the Q of this circuit? - Page 1
|
[
{
"post_id": "",
"author": "SoftwareSamurai",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 10, 2011, 03:49:25 pm",
"content": "While tying to learn more about bandpass filters, I stumbled acrossthis circuit(see pic). Does anyone know how to calculate the Q of this filter?I know that the addition of the Rload changes the Q, but I'm not sure how to factor both R1 and Rload into the math."
},
{
"post_id": "",
"author": "Rufus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2011, 04:11:46 pm",
"content": "V1 has zero impedance. If you replace V1 with a line it becomes obvious that R1 and Rload are in parallel."
},
{
"post_id": "",
"author": "jimmc",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 10, 2011, 07:44:04 pm",
"content": "The resonant frequency of L1 & C1 is 159.15Hz at this frequency the reactance (X) of either is 100 Ohm.As Rufus has said RSand RLappear in parallel so their combined resistance (R) is 333.3 Ohm.Calculate Q as R/X = 3.333Jim"
},
{
"post_id": "",
"author": "SoftwareSamurai",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 10, 2011, 09:15:23 pm",
"content": "Thanks Rufus. I hadn't thought of V1 with zero impedance. I think that's what I was missing.Thanks Jim. I thought that Q = R/X, but I wasn't calculating R correctly which made me think that I had the wrong formula for Q."
}
] |
2025-10-17T20:37:42.296178
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(sorry)-op-amps/
|
(Sorry) op amps. - Page 1
|
[
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 20, 2017, 01:24:12 pm",
"content": "I've spent two days playing with op amps. Everything is grand with DC: comparators, followers, neg fb gain etc.It's when I put a small AC signal in that I run into problems.I have an input from my sound card, it's line level, +- about ~250mV around the ground on the RCA lead (normal 0V, it's 0V potential to the 0V rail on my breadboard)The opamp has 0V-12V rails.I have a 6V virtual ground from either a (variable) voltage divider or an opamp buffer producing 6V.TLDR;How do you correctly lift the input \"ground\" to the rail split virtual ground so you get VMax - Virtual Ground - VMin. In my case 6V +- 250mV and 6V +- 2000mV on the output?Skipping many hours of reading, you tubing, tinkering and genuine concern for my sound card RCA outputs. I did manage to get an amplified signal. But it had issues.Basically I had to decouple the input via a series cap, apply a pull up voltage onto that signal to raise it up above the lower rail and I got a signal.It felt very wrong applying (at first 2.5V) to the \"output\" of the RCA though even with the series cap \"decoupling\" it. I tried the opamp buffer (rail splitter) to get 6V which tested out fine, but when I applied that to the input signal I got a pop and the channel went mute ( I mean the sound card cut it's output off and the headphones went off). I don't think it liked it, but it thankfully recovered when I removed the voltage.Back to using a voltage divider for the \"virtual\" ground at 2.5V. I was able to get a maximum gain of about x4 before the op amp either clipped or just stopped working and the output collapsed. So that was something like 800mV p-p. If I wound the gain higher I clipped on the top rail, if I wound the reference voltage up the output collapsed.I gather the issue is the op amp is amplifying the virtual ground as well, so if I give it +2.5V and add my +-200mV AC signal @ x4 gain I getting 800mV peak to peak on a 2.5x4=10V DC offset. 9.2V to 10.8V. I confirmed this with the multi-meter. If I took the ref voltage up the amp clipped until it collapsed against the top rail. If I took the ref voltage down it collapsed against the lower rail.So do I apply the virtual ground voltage to both inverting and non-inverting or ... more likely am I just in a muddle.I think I'm just missing one piece of the puzzle or have miss interpreted something fundamental along the way regarding virtual ground on the op amp, versus the input signal ground.(Also... assuming I get this working, how would I then be able to bias the output 6V -+1000mV back down to normal 0V ground to send on to something like a speaker? Thinking out load, if I pass it through a series cap pulled to 0V ground on the speaker side, will that work?)"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 20, 2017, 01:41:31 pm",
"content": "Quote from: paulca on November 20, 2017, 01:24:12 pmThis is how it is usually done. You shall seek for application notes and reference designs from IC manufacturers, see how they suggest to implement stuff.Example:http://www.ti.com/lit/ds/symlink/tpa4861.pdfQuoteWhen use series capacitor, you don't apply voltage. You just create a \"pop\" when it is chargedAgain it is ok."
},
{
"post_id": "",
"author": "aiq25",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 20, 2017, 01:45:02 pm",
"content": "Do you have a schematic?I'm not familiar with audio applications. You can use differential amplifiers to adjust DC levels or just a DC blocking cap with a resistor divider."
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 20, 2017, 01:46:21 pm",
"content": "This might help -https://www.ti.com/lit/an/sloa030a/sloa030a.pdfA calculator/design tool -http://www.analog.com/en/design-center/interactive-design-tools/adi-diffampcalc.htmlRegards, Dana."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 20, 2017, 03:31:12 pm",
"content": "The pop was probably the large 1uF cap, I replaced it with a 50nF cap and the pop is now tiny and the RCA backs off less.I'm still lost. So I took a step back and removed the op amp completely.I put two probes on the input. One before the cap (direct from the RCA).RCA Output (Probe1) ---||--- (Probe2)|0VWith just that I get about 400mVpp on Probe1 and 200mVpp on Probe2. Is this just expected loss across the coupling cap?If I then pull the Probe 2 side up to 6V using a voltage divider I get about 100mVpp at Probe2 and a 6V DC offset (what I wanted).RCA Output (Probe1) ---||--- (Probe2) --- 6V|0VHowever if I try and pull Probe2 side up to 6V with the opamp buffer rail splitter the RCA output drops way down and I get about 70mVpp at Probe2 ... most of which is computer RF and it's virtually impossible to distinguish a signal on the oscilloscope.So I'm thinking I'm screwing up the impedances. Should the +6V from the virtual ground have a resistor on it?I tried pulling Probe2 side to ground with a 10K resistor, but it didn't make any difference or muted the signal all together.RCA Output (Probe1) ---||--- (Probe2) --- 6V --- 10K --- 0V|0VIf I can get this bit right, then it's a start."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 20, 2017, 03:35:29 pm",
"content": "Quote from: paulca on November 20, 2017, 03:31:12 pmI would say unacceptable signal level loss. Decoupling capacitance is too small. Don't go below 0.1uF (100 nF). 1uF seems about right. And don't worry about pops. They are expected for simple/single_power_rail amps.Further reading:https://www.allaboutcircuits.com/tools/capacitor-impedance-calculator/"
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 20, 2017, 03:46:08 pm",
"content": "I found this:QuoteSource:https://en.wikipedia.org/wiki/Line_level#Line_outDoes that mean I should have something like this, below, to AC couple it and give it the 10k impedance it expects to drive?RCA Output ---||---> 6Vgnd --> amplifier input|10K|GNDThe capacitor impedance is tiny compared to 10K it's like 100Ohms.Quote from: ogden on November 20, 2017, 03:35:29 pmI'm less worried about the pops and more where I hear them and the result after them. The headphone amp has a line level pass through, it's just electrically wired through. As the same time it's driving the headphones via it's own amp. I hear the pop through the headphones and the channel I just hooked up drops to considerably lower volume that the untinkered channel."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 20, 2017, 03:57:12 pm",
"content": "Actually I think in my original circuit the signal (Probe 1 side) has no circuit path. It's floating in the breeze. The oscilloscope sees the 400mV only because it has a GND on the probe shared with the line input. The left side of the circuit before the cap has no route to GND, so no current. When I then pull that floating voltage through the cap and up to 6V it gets all but lost in the noise.I don't have anymore time to play this afternoon, I'll have to pick it up later."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 20, 2017, 04:03:39 pm",
"content": "Here is a discussion of a simple amplifier with rail splitter circuit and it talks directly about the problems you are having:https://electronics.stackexchange.com/questions/153911/single-supply-op-amp-audio-amplifierHere is a much better article but for more advanced circuits:http://www.ti.com/sc/docs/apps/msp/journal/nov2000/nov_08.pdf"
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 20, 2017, 04:30:06 pm",
"content": "Quote from: rstofer on November 20, 2017, 04:03:39 pmAh ha!QuoteThat solves the \"amplifying the DC offset\" issue.I might get somewhere now.Thanks."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 20, 2017, 06:35:31 pm",
"content": "Quote from: paulca on November 20, 2017, 03:57:12 pmWhat you say actually does no makes sense unless youdo notconnect GND of the signal source to GND of the amplifier. If GND of the both are common and ground of both probes are connected to said GND connection - nothing is floating in the breeze. You shall try to show circuits you are talking about - to avoid misunderstandings"
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 20, 2017, 08:10:18 pm",
"content": "It works!The output from my PC is foul for noise, but the caps filter it right out.It's an LM741 and it obviously doesn't make a good audio amp, so I'm not even going to connect it to a speaker. It was just an exercise in opamps and AC.It responds to anything above about 30Hz and cuts off hard at about 15KHz. Not sure if that's the LM741 or more likely the RC values.Thanks for all the help I learnt a lot today.Next on the list is back to digital stuff (programming an LCD display from the PI), thankfully as this analogue stuff is hard on the head."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 22, 2017, 12:56:27 pm",
"content": "Quote from: ogden on November 20, 2017, 06:35:31 pmI was getting all confused with the whole AC coupling cap considering it as being effectively an insulator and only the fluctuations in current influencing the other side. So I then seen the signal wire from the RCA as \"floating\" with no connection to ground.Of course this is not true, but it's still an area of confusion.Out of interest, I did connect it to GND on the input side of the AC coupling cap via a 10K and it did absolutely nothing (visible)."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 22, 2017, 02:21:31 pm",
"content": "The RCA jacks on your sound card are probably connected to earth ground inside the PC. Is there any part of your amplifier that is referenced to earth ground? Probably not... It depends on the power source.However, the ground lead on your scope probe IS referenced to earth ground. So, the ground side of your signal is probably going to earth by way of the power cord and then coming back in via your scope probe.There really are no one wire circuits."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 22, 2017, 02:48:05 pm",
"content": "Quote from: rstofer on November 22, 2017, 02:21:31 pmThe anomaly is that my scope probe is not referenced to earth ground in any way when I pull the power cord out of the laptop just it's internal battery 0V. Note the scope is on the laptop, RCA outputs from the PC. Using a scope on a laptop battery allows this test and allows me to be absolutely sure I cannot short the probes to ground and fry stuff.One route the signal has to complete a circuit is through the AC coupling cap, through the amp breadboard circuitry and into the PSU GND which (IIRC) is floating, not clamped to the earth binding post. Eventually I assume that ends up some how onto the mains neutral.The shorter path is of course that the signal ground on the breadboard is shared with the PSU ground, so it will take the shortest route to that ground after passing through the AC coupling cap.Of course if I disconnect the RCA GND from the breadboard I still get signal but with a huge 50Hz mains hum as the signal circuit is forced to travel all the way through the whole Breadboard, PSU, Mains plugs etc. I expect if I used my phone as audio source (assuming it was running on battery) this route would not be available and I would get no signal at all. Similarly if I ran the breadboard amp on a battery there would be no GND path either and no signal.My only confusion was with the AC coupling cap as I was thinking of it as an isolator/insulator when of course it's not and current does pass through it and potential does exist across it. The fact the only route to GND for the signal exists beyond it doesn't matter, it is still a route. I watched some videos on the theory of capacitors and it gets pretty complicated pretty quickly."
}
] |
2025-10-17T18:44:22.882995
| 15
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(stm32)-why-a-0-in-the-output-data-register-activates-the-n-mos/
|
[STM32] Why a “0” in the output data register activates the N-MOS? - Page 1
|
[
{
"post_id": "",
"author": "unscripted",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 24, 2022, 12:04:49 am",
"content": "Really a beginner question.. but I thought a N-MOS like a N-Channel MOSFET was activated with \"1\" logic but while using a STM32 GPIO as open drain output I realized the N-MOS is activated with a \"0\". I would appreciate any quick enlightenment or suggested documentation to read more about N-MOS and P-MOS. Thanks."
},
{
"post_id": "",
"author": "fourfathom",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2022, 12:52:22 am",
"content": "You are correct about turning on an isolated NMOS transistor, but in this case the magic happens in that \"Output Control\" box. There the \"0\" is inverted (and potentially disabled in order to force both the NMOS and PMOS transistors off when you want to use that pin as an input). The NMOS/PMOS transistors invert the polarity once again and so an logic \"0\" becomes 0V at the pin."
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2022, 11:58:54 am",
"content": "It's an arbitrary choice. 0 corresponds to output pulled down to GND, 1 corresponds to output pulled high to Vcc. In open drain mode, latter means, pulled high by external resistor. The polarity of voltages is of course the same in push-pull and open-drain modes.One could have chosen opposite logic, so that 0 = higher voltage and 1 = lower voltage, but IMHO, that would be pretty weird. Even more weird would be to use different notations in push-pull vs. open drain mode."
}
] |
2025-10-17T17:06:31.329999
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/(suggestions)-what-is-wrong-with-this-schematic/
|
[Suggestions] What is wrong with this schematic? - Page 1
|
[
{
"post_id": "",
"author": "WaRc3L",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 30, 2015, 02:12:05 pm",
"content": "Hello everybody,I am newbie into design of PCB and I need your help for a suggestions about this schematic. It's a simple triangular-wave generator with a potentiometer to modify the frequency of the signal.Can I do it better?, what's seen in the schematic that \"cries\" your eyes?Thanks for all, and sorry for my english.pD: Do you know any tutorials or suggestions on Internet to pass the schematic into a board-design PCB?, I have seen the BenHeckShow tutorial and Jeremy Blunm on youtube, but it's not enough for me...Regards,Marcel"
},
{
"post_id": "",
"author": "McBryce",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2015, 02:18:50 pm",
"content": "The first thing that's obvious is that it's extremely difficult to read at a glance. did you make the 741 symbol yourself? Eagle already has a 741 symbol in it's library. The circuit is much easier to understand if you use the standard op-amp type symbol (see attachment).McBryce."
},
{
"post_id": "",
"author": "WaRc3L",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 30, 2015, 02:26:13 pm",
"content": "Quote from: McBryce on July 30, 2015, 02:18:50 pmYeah, it's obvious. I found the symbol into ST Microelectronics, I don't remember why. Thanks!!!.Any other suggestions?Regards,Marcel"
},
{
"post_id": "",
"author": "McBryce",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2015, 02:41:36 pm",
"content": "The green dots on the component pins aren't necessary unless there is more than one wire (net) going to the pin. The dots are usually just for joining two wires together. A single wire going to a pin is automatically connected. It's not wrong how you have it, just more work than is needed.McBryce."
},
{
"post_id": "",
"author": "WaRc3L",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 30, 2015, 06:15:54 pm",
"content": "Perfect!!!, thanks a lotRegards,Marcel"
},
{
"post_id": "",
"author": "Neilm",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2015, 07:02:57 pm",
"content": "A personal preference of mine - if two wires are crossing and are connected, I don't have them in the form of a cross as you have for your TRI port, but will offset them to form 2 T intersections. This means that I can tell at a glance that when one wire is going over another they are not connected rather than having to look. . It also means that if I see dot in this situation, I know to have a good look to check they should be connected."
},
{
"post_id": "",
"author": "codeboy2k",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2015, 07:37:27 pm",
"content": "Quote from: Neilm on July 30, 2015, 07:02:57 pmYes, this is very important, and something I always do too. Crossed wires never connect, and connections are only made using 'T' junctions, never '+' like that.This way you always know when something is or is not connected -->> \"T\" junctions ALWAYS connect. \"+\" junctions NEVER connect."
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2015, 07:39:26 pm",
"content": "Multiple standards require this, and for a reason."
},
{
"post_id": "",
"author": "WaRc3L",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 31, 2015, 03:32:02 pm",
"content": "Quote from: Neilm on July 30, 2015, 07:02:57 pmWow, thanks Neilm and codeboy2k!!.With all about your suggestions, I made this schematic. Is it better?.And, to reuse the post, I designed this PCB board with the Autorouter of Eagle. What do you think?, Is it really finished?.I remember that I am newbie with the designs of PCB...Regards,Marcel"
},
{
"post_id": "",
"author": "milow",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "July 31, 2015, 06:16:10 pm",
"content": "The triangle wave is at the output of U1. Right now, you would get a linear combination of the triangle wave and the rectangular wave."
},
{
"post_id": "",
"author": "WaRc3L",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 31, 2015, 07:55:37 pm",
"content": "Quote from: milow on July 31, 2015, 06:16:10 pmThanks for the annotation!"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 31, 2015, 08:59:54 pm",
"content": "Do you want to vary the frequency of the triangle wave, without changing its amplitude? If so then you need to make R1 the potentiometer and leave R3 fixed.The 741 is only suitable for low frequencies. You won't get a very good squarewave above a couple of kHz. I haven't done any calculations so don't know what frequency it'll oscillate at."
},
{
"post_id": "",
"author": "Hideki",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 31, 2015, 10:34:37 pm",
"content": "Quote from: WaRc3L on July 31, 2015, 03:32:02 pmNo. While it is connected up according to the schematic, it does looks like what you get when you let a beginner use the autorouter. The only reason to use an autorouter if you're a beginner is to try it out and learn some of the possible ways that traces can be connected. Once you get better at figuring that out you should do it manually... every time, every single time, always. After you get really good at it (maybe some years later) you can consider looking at autorouters again.The components are placed almost at random with large areas of unused space instead of grouping the components in any way. Strange connections all over the place. When you have that few components you really should try keeping all the connections on one side. Bottom if through hole and top if surface mounted. 2 layer prototype boards cost the same, so it's not that you HAVE to. It's just good style. Especially when you're learning how to do it."
}
] |
2025-10-17T19:36:20.618440
| 13
|
electronics
|
beginners
| true
|
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