Design of an ESR Meter from Practical Television 1999 - Page 1
Forum section: electronics / projects

author: Tim88
author_rank: Regular Contributor
timestamp: October 31, 2023, 04:03:35 pm
content: Good day everyone, snowing here in NW Indiana. Anyway, In many of Shango66's vids on the youtube, he uses a capacitor wizard to quickly look around for bad caps. Those things are ridiculously expensive and have always wanted to build one. I stumbled across this on the interweb looking for a good build, looks promising. Forgot to screenshot the protection addition which is two 1N4007 diodes back to back in series with a 1A circuit protector on one of the test leads. Links to the full articles listed below. Would be very inexpensive to build and handy, thoughts...?https://www.worldradiohistory.com/UK/Practical-Television/90s/Television-1999-03.pdfhttps://www.worldradiohistory.com/UK/Practical-Television/90s/Television-1999-04.pdf

author: daisizhou
author_rank: Super Contributor
timestamp: November 01, 2023, 12:12:12 am
content: http://www.crystalradio.cn/forum.php?mod=viewthread&tid=664750This may be better

author: The Electrician
author_rank: Frequent Contributor
timestamp: November 01, 2023, 12:50:20 am
content: Quote from: Tim88 on October 31, 2023, 04:03:35 pmIf you can afford a FLIR TG165-X, then you can afford a DE5000 LCR meter.

author: Tim88
author_rank: Regular Contributor
timestamp: November 01, 2023, 12:59:44 am
content: The FLIR was worth the money, the cap-wizard, not so much...

author: The Electrician
author_rank: Frequent Contributor
timestamp: November 01, 2023, 01:05:24 am
content: CapWizard is $209 on eBay, DE5000 can be had for less than $100. If you buy a DE5000, you get much more than just an ESR meter; you get a decent LCR meter that can measure ESR at 120 Hz for capacitors used in linear grid frequency power supplies, and also at 100 kHz for capacitors used in switchers like the dedicated ESR meters, and can also measure inductors.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: November 01, 2023, 02:12:27 am
content: Hi, you can also check this thread:https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/regards,Jay_Diddy_B

author: Tim88
author_rank: Regular Contributor
timestamp: November 27, 2023, 09:20:25 pm
content: Over the Thanksgiving, I built this bad boy and have some issues. Note, I am just a hobbyist, learning as I go. Anyway, on the schematic from the article, they have one of the probes connected to to the oscillator circuit between the lamp and the 1 ohm R3. This has to be an error? I can scope the out put fine from the opamp at pin 1 but not on the point on the schematic. My understanding of the Wien Bridge Oscillator is that the bulb is part of the feedback resistance and not sure why they tap it off where they do? Thanks!

author: RoGeorge
author_rank: Super Contributor
timestamp: November 27, 2023, 09:38:05 pm
content: The output is from the 1 ohm resistor because only a small fraction of the total voltage is used for measuring. The idea is to have a very small AC voltage when testing, so it won't damage the circuit to be measured (the ESR meter can be used to measure in-circuit capacitors, without desoldering the capacitor first, only powered off).At the 1 ohm resistor, the AC voltage is supposed to be about 100 times or so smaller than what you measured at pin 1 of the Wien oscillator opamp. At the 1 ohm point, the voltage should be visible with the oscilloscope in the mV range.

author: Tim88
author_rank: Regular Contributor
timestamp: November 27, 2023, 09:53:05 pm
content: Thank you for explaining that! I can indeed get a very small signal there. In the setup of the meter, they speak of a 5V peak to peak setting but that must be measured at pin 1 of the op amp. I attached a copy the schematic I made and a copy of the article for anyone else interested. I just need to explore further why my buzzer no buzzy and meter no movy...

author: RoGeorge
author_rank: Super Contributor
timestamp: November 27, 2023, 10:01:11 pm
content: The schematic in the last 'sch.png' can not work. With D7 and D8 back to back, nothing will pass through them. D7 and D8 must to be removed, as in the original article.

author: Tim88
author_rank: Regular Contributor
timestamp: November 27, 2023, 10:05:58 pm
content: Ok good, where would a guy put the protection circuit?"A small board with two 1N4007 diodes wired back-to-back and a 1A (N25) circuit protector in series with one of the test leads can be mounted on the back of the meter movement."

author: RoGeorge
author_rank: Super Contributor
timestamp: November 27, 2023, 11:09:09 pm
content: Try the one in the attachment, it's from an existing ESR-meter. No fuse. You'll still need to discharge the capacitors before measuring them, but in case you forget, the instrument should survive. The entire circuit is supposed to be connected between the resistors R3 and R4 in the original schematic from the magazine article (entire circuit connected instead of Cx).With the extra C of 0.47uF/600V as in the attached schematic, the same instrument will be able to also measure the internal resistance of battery cells or battery packs.

author: Tim88
author_rank: Regular Contributor
timestamp: November 27, 2023, 11:18:08 pm
content: Cool beans, will give it a shot. Figgered out the buzzer, had an AC one instead of a DC buzzer. Narrowing down the meter problem. Thanks again!

author: Tim88
author_rank: Regular Contributor
timestamp: November 28, 2023, 12:16:56 am
content: What a dummy, I got a 100mA meter instead of a 100 uA meter. On the plus side, the contraption works!

author: Tim88
author_rank: Regular Contributor
timestamp: November 28, 2023, 01:09:03 am
content: Updated schematic.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 28, 2023, 01:21:30 am
content: Many mA (or bigger) range galvanometers are in fact 50-100uA meters with a parallel shunt internally. If your model can be dismantled, open it and remove any resistor found inside.

author: Tim88
author_rank: Regular Contributor
timestamp: November 28, 2023, 01:25:56 am
content: I was wondering that very question, gonna take it apart and see what is inside...

author: RoGeorge
author_rank: Super Contributor
timestamp: November 28, 2023, 01:29:19 am
content: Note that the battery I've drawn can be placed either way, the instrument doesn't have a +/- polarity. Same for the capacitors, can be oriented either way. R17/10k might be too small, the original was 1 Megaohm (1000k\$\Omega\$/0.5W)

author: Tim88
author_rank: Regular Contributor
timestamp: November 28, 2023, 02:12:50 am
content: Ya, a typo on that resistor. Will delete the polarity symbols as well.

author: Tim88
author_rank: Regular Contributor
timestamp: November 28, 2023, 02:15:34 am
content: Fixed

author: Hamelec
author_rank: Regular Contributor
timestamp: November 28, 2023, 02:23:12 pm
content: I built a similar device in 2006, but without the buzzer function. It also works with just a single 9V battery - you might want to check yours...

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 28, 2023, 02:37:05 pm
content: Quote from: Tim88 on November 28, 2023, 02:15:34 amWell, is the project finished? How did it go overall? Would you build it again? Any post-completion screenshots to share?- Wil

author: Tim88
author_rank: Regular Contributor
timestamp: November 28, 2023, 04:30:13 pm
content: The project is 95% finished, have a couple things to work out then will test it on some caps. It went better than expected, fitting all the components on a small board was quite the challenge. I would do it again, assuming it performs well. Will post a bunch of pics soon!

author: CJay
author_rank: Super Contributor
timestamp: November 28, 2023, 07:45:25 pm
content: Quote from: The Electrician on November 01, 2023, 12:50:20 amIf I'd bought a FLIR TG165 then I'd definitely not be able to afford a DE5000 #Skint

author: Tim88
author_rank: Regular Contributor
timestamp: November 28, 2023, 08:09:21 pm
content: Here is some test cap pics, the daggum thing looks to be right on the money. The meter pictured ranges from 0-300uA so at the 10 mark is 100uA or zero ohms. Tested 3 caps, one at under 1, one at 3 and one over 40 esr respectively. Meter scale and board pic also attached. Also the oscillator set at 5v peak to peak at pin 1 of U1. Frequency is off a tad but close enough. The bulb used was a JKL COMPONENTS / 6838 in the oscillator.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 28, 2023, 08:36:42 pm
content: Quote from: Tim88 on November 28, 2023, 08:09:21 pmVery nice!

author: RoGeorge
author_rank: Super Contributor
timestamp: November 28, 2023, 09:23:20 pm
content: Nice!Do you happen to have any battery at hand? It should be possible to tell which ones are discharged by measuring their internal resistance, or to tell which rechargeable from the same lot got more damage with time.

author: Tim88
author_rank: Regular Contributor
timestamp: November 29, 2023, 12:47:14 am
content: I want to get that protection circuit installed before I go checking any batteries.

author: skipp
author_rank: Newbie
timestamp: December 01, 2023, 08:09:57 am
content: Buy a kit and build one that's what I did. I am only just a beginner myself. but look on aliexpress they have them fairly cheaply.

author: Hamelec
author_rank: Regular Contributor
timestamp: December 01, 2023, 05:17:42 pm
content: I don't know any kit which is able to measure the ESR incircuit and under supply voltage, like this one

author: Tim88
author_rank: Regular Contributor
timestamp: January 09, 2024, 08:34:03 pm
content: Finally got the ESR tester done, found a very cool enclosure for it for $10, link below. I also attached a couple meter scale pics one colour and the other not.https://www.aliexpress.us/item/2255800409490545.html?spm=a2g0o.order_list.order_list_main.11.12de1802Jjm7fX&gatewayAdapt=glo2usameter bw.pdf(783.16 kB - downloaded 90 times.)meter colour.pdf(797.6 kB - downloaded 87 times.)

author: soldar
author_rank: Super Contributor
timestamp: January 09, 2024, 09:44:50 pm
content: Variations of this design have been going around for quite some time. I had one on my web site for many years and that page gathered many visits.Poptronics magazine in July 2001, page 25.Italian magazine Nuova Elettronica issue 212 dated October 2002IZ7ATH also published it in QSL.netEdit: It is not the same circuit. The one I mentioned uses a bridge of four resistors and a single TL084.