In circuit ESR meter Project - Page 1
Forum section: electronics / projects

author: backd00r
author_rank: Contributor
timestamp: April 10, 2015, 04:15:51 am
content: I am thinking about making a 100khz in circuit ESR meter and I wonder if anyone has a good schematics to follow or similar project link to recommend. I dont want to buy one but rather make a decent one and learn more about how they are made in the process.thanks,

author: Refrigerator
author_rank: Super Contributor
timestamp: April 10, 2015, 04:30:14 am
content: https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/

author: dannyf
author_rank: Super Contributor
timestamp: April 10, 2015, 01:37:31 pm
content: Depending on what you meant by "good".I built one using just 1 (dual) opamp and a few passives / diodes.

author: w2aew
author_rank: Super Contributor
timestamp: April 10, 2015, 04:07:36 pm
content: Lots of ways to do this - plenty of designs out there. I like the 5 transistor one by Jay, but haven't had a chance to build it yet for fun. Here's the one that I built about 9 years ago...

author: Spike
author_rank: Regular Contributor
timestamp: April 13, 2015, 01:00:16 am
content: While Alan's comments are endorsement enough for the 5-transistor circuit, I'd like to add the beginners perspective. As a software guy with a long-simmering interest in electronics that I'm finally feeding, I really like this circuit. I breadboarded this a while back and it worked beautifully. I'm in the process of laying out a through-hole board for it at the moment.The thing I like so much about this circuit is that, while it's relatively simple and works well, each of it's functional pieces offers a great learning opportunity. Once I got this working on the breadboard, I spent a bit of time studying each piece and learned lots of fundamentals along the way. The oscillator, bridge and finally the differential amplifier and meter circuit all offered great excursions into various aspects of analog electronics that I found very valuable. I'd heartily recommend this circuit to anyone just starting out in electronics such as myself. A big thanks to JDB for sharing this.Along the way I also explored various options to power the circuit on batteries including a boost converter, which for the old-school 5-trainsistor is maybe a bit out of place. It did, though, create an interest in building a simple adjustable load, and so I started poking around with Dave's. Again, another excursion that turned out to be a great learning experience. It was during this exploration that I learned more than I thought I could about loop stability. Argh!At the risk of a thread hijack, that brings me to a request while I have you in this thread, Alan. I would sorely love to see you do a video on loop stability, specifically one where you talk about the practical aspects of measuring gain and phase. Maybe show how to properly inject a signal and how to use the oscilloscope for yet another thing it wasn't meant to do. ;-)Thanks to all for sharing your expertise on this forum.

author: backd00r
author_rank: Contributor
timestamp: April 24, 2015, 06:13:08 pm
content: Thanks all for the replies. I will study each one and I already like the 5 Transistor one I think that would be my next project once this semester is over with.

author: markce
author_rank: Regular Contributor
timestamp: April 25, 2015, 09:54:12 pm
content: I build an opamp version of an ic ESR checker myself. This is what I learned.It's a big plus if the ESR indication is not power supply dependent (battery supply). 100kHz is too high, 60kHz served me better. Use sine wave to avoid errors. Keep in mind your meter does indicate Zc total, not just ESR. Mine is used mainly for checking elco's.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 28, 2015, 01:28:49 am
content: Hi,The 5 transistor ESR meter is fairly easy to build, and will work with most junk box components. The critical parts are the diodes and the meter.If you need an ESR meter that is really well protected take a look at my other ESR meter design:https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/msg341177/#msg341177This one uses a DMM for the display.Regards,Jay_Diddy_B

author: backd00r
author_rank: Contributor
timestamp: September 29, 2015, 07:17:41 pm
content: Hi,I have been looking at different schematics and understanding them. But I would like to understand how the esr meter works first, especially the in circuit one. Because let say you have caps in parallel or something like that how would it determine the esr of one of the caps seperately. please post any documents or videos you might have.Thank you

author: singapol
author_rank: Frequent Contributor
timestamp: September 30, 2015, 04:23:06 am
content: I hate to dampen your learning enthusiasm but as a hobbyist myself I built a 2 opamp esr meterand later found that while it works as stated because it can measure in-circuit it does not have the resolution to give one confidence about the measurement as it can only measure down to 1 ohm only.Initially I did manage to use it to troubleshoot a repair but as I "learned" more about esr it was obviousthat the esr meter I built was not "good" enough. In short I bought a commercially made one, a chineseMESR100 V2 ( version 2). It could measure down to miliohms and mcu controlled with a colour lcd. NowI humbly ask can anyone diy something like this and look as good for the price? Can also get the cap meter as a combo. Of course if you want something better than this then a lab grade esr meter from the big famous manufacturers is the way to go.Some might say "A bad carpenter blames his tool" but all the theory and knowledge one has aquired will come to zero if you don't have the "right" tool for the job that's why the endless discussions on multimeter's performance and safety issues until someone ends up with a 8.5 digit monster.Overkill? yes but just like having a sports car driving in city traffic it's just gives you confidence knowingif you need the performance it's there.QuoteLike others have said it basically measures total impedance. Impedance is ac equivalent of dc resistance.So series impedance adds and parallel impedance also obey ohms law that is: equal impedances divide by the number of individual ones. A search on the internet will yield many links and papers on the subject.

author: kripton2035
author_rank: Super Contributor
timestamp: September 30, 2015, 05:57:09 am
content: if you want a lot of schematics to look at, then go to my esr repository (web link below)