Re: DIY ESR Meter advice (What one to build?!?!)  - Page 1
Forum section: electronics / beginners

author: NH-GrizzlyBear
author_rank: Contributor
timestamp: November 10, 2015, 05:57:00 pm
content: Hi, I'm new to the forum and I have a question related to an ESR meter I recently purchased and built.http://www.electronics-diy.com/esr-meter.phpIt works very well, but I have concerns about putting it into a case and extending the test connector, as large diameter leaded components will not fit the test connector. i have sent an e-mail to "electronics-diy.com" and have not received a response!Does anyone have this unit that can answer whether I can extend the test connector without degradation of function or performance?Thank you.Jon

author: kripton2035
author_rank: Super Contributor
timestamp: November 10, 2015, 06:03:03 pm
content: you can but you have to adjust the zero ohm (dont know if there is a pot for that ?) to compensate the length of the probes wires.but for esr as you don't need the milliohm that's not really critical.

author: NH-GrizzlyBear
author_rank: Contributor
timestamp: November 10, 2015, 06:31:38 pm
content: There is only a 'test' push button.In the instruction manual, there is a 'calibrate' function, where all three pins are shorted to each other at the test connector. It puts the unit into calibration and after that it will prompt me to remove the shorts and put a 100nF cap across pin1 to pin3.I would also like to put a DPDT toggle switch (center off) in parallel with the test connector, so I can have an easy calibrate mode function.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: November 10, 2015, 07:09:59 pm
content: Are these meters reliable as your only ESR meter?

author: Radio Tech
author_rank: Frequent Contributor
timestamp: November 10, 2015, 07:14:15 pm
content: Quote from: Aodhan145 on November 10, 2015, 07:09:59 pmI have found that the older ones are not as accurate as a stand alone unit.However some of the newer units seem to be a lot better. I just ordered a new one and posted a video here about it:https://www.eevblog.com/forum/other-blog-specific/diy-m12864-graphics-version-transistor-tester-kit-lcr-esr-pwm/

author: Aodhan145
author_rank: Frequent Contributor
timestamp: November 10, 2015, 07:14:43 pm
content: Quote from: Radio Tech on November 10, 2015, 07:14:15 pmThanks.

author: NH-GrizzlyBear
author_rank: Contributor
timestamp: November 11, 2015, 11:50:34 pm
content: Quote from: NH-GrizzlyBear on November 10, 2015, 05:57:00 pmI tried extending the test connector with 3 26ga wires 3" long and recalibrated. The 100nF measured about 3-4nF less after extension. I suspect that the arrangement of the wires is affecting the overall capacitance.Any ideas how I can extend the wires and minimize stray capacitance? Are there any low-capacitance wire near this gauge that can be purchased? What about ribbon cable which has equal separation?I had also wanted to add a DPDT (center off) switch to provide an easier calibration, but I think this will contribute to more stray capacitance!Does anyone have any suggestions and/or a solution that I can try?Jon

author: GBowes
author_rank: Contributor
timestamp: November 14, 2015, 03:13:19 pm
content: First, I think it is important that you realize that this is just a relabeled version of the ubiquitous Component Tester. It was originally designed as a transistor tester. Over the past 4 or 5 years, the author of the software has done a masterful job expanding the functionality and increasing its accuracy. It is a great little device and I use one of the versions I have almost daily. With that said, it may never be a great ESR meter or a substitute for purpose built device. It's primary limitation for accurate ESR measurements is the frequency of the test signal. If one is simply interested in comparing two capacitors or identifying a dying or dead old electrolytic, it will usually be fine but absolute values measured will be misleading.The measurement of capacitance has been significantly improved between early software versions and the current 1.11k or 1.12k versions, and can be quite accurate. But this accuracy is dependent on some the software configuration and especially on the accuracy and stability of a 5.0v VCC (and possibly the voltage reference if so equipped). The kit shown in the OP post will not be very accurate as it is using a 78L05 and apparently no external reference.For more information than anyone could want on these devices, there are two really long threads full of useful information.The software author's thread:https://www.mikrocontroller.net/topic/248078#This is generally in German, however, Google translate does an adequate job to get the benefit.There is also this thread that complements the official thread with some very helpful members:https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/For those without the patience to read these years of collected wisdom, the documentation provides some invaluable information that will help get the best out of these great little devices.https://www.mikrocontroller.net/wikifiles/8/8f/Ttester_eng111k.pdfTo the OP's questions, extending the test leads should introduce no real problem is using quality wire and connectors. I would suggest using 18 ga tinned, flexible (many strands) single conductors and would remove the test socket and solder them directly to the PCB. Good quality DMM leads would be a great alternative. The resistance of these leads is more important than the small values of stray capacitance to the measurement of both capacitance and resistance. The self calibration will offset reasonable amounts of resistance in the leads so as long as connections are good and consistent, the accuracy will be more than adequate.Graham