Digital ESR meter design

[stefan_trekkie]

Hi all.. I will be building up new ESR meter from known design:

http://electronics-diy.com/esr-meter-low-resistance-meter.php

I was gravitating to Jay_Diddy_B's 5 Transistor ESR Meter but the use of analog μA meter in for home use only in my experience.  I have destroyed few analog meters by transporting them with my bicycle on cobblestone or bad streets. The second reason is that big caps have very small ESR even bad ones. The resolution is not so grate below 1 Ω. I work on industrial stuff.

Anyway .. I have ordered the parts. The ICL7107 analog to digital converter + direct drive 3½ digits will be nice with 0.01 resolution .. I have the 7 segment displays and op amps .. And Russian made 555s

[Conrad Hoffman]

You might also like to build a bridge for large caps. Simple and rugged. I did one here- http://www.conradhoffman.com/cap_bridge.pdf

[stefan_trekkie]

  something went wrong with my chloride. Even wormed up it does not want to each for 3 hours and start to dissolve the trace cover .
Fail I have 

Plan B .. Universal board bodge the f*** up on this thing

[kripton2035]

in the schematic, Cx is connected with 2 wires only. you will never get 0.01 ohms accuracy with a 2-wires measurement. you need 4-wires.


the elektor esr meter, from 2002, uses most of the same circuits, and has this 4-wires measurement method.
http://kripton2035.free.fr/commercial%20esr/esr-elektor-sept.html


Edit: article is available here : https://elektrotanya.com/esr-meter_elektor-electronics-2002-09_icl7106_by-flemming-jensen_project.pdf/download.html

[daisizhou]

look
This one is good, I do n’t know if it is suitable for you

[kripton2035]

same problem : Cx is connected only with 2 wires.

[Conrad Hoffman]

You can zero out the wires, though 4-wire kelvin is better. The driving impedance doesn't look all that low, so not sure how low the circuit can really detect.

[stefan_trekkie]

I am almost done with the original design and it is too late. I cannot see haw can be reconfigured and separate drive single from the measuring signal that easily but i will thing about if the meter is not good as what is intend to be.

[Shock]

If your circuit has calibration or can zero out the lead resistance you can get down into the 10s of milliohms with 2 wire method. Bob Parkers ESR MKII is an example of this. If you need more accuracy or resolution I would argue you should be looking at an LCR meter.

[Jay_Diddy_B]

Stefan_Trekkie,

You may want to consider my other design:

https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/


Regards,
Jay_Diddy_B

[stefan_trekkie]

If your circuit has calibration or can zero out the lead resistance

Yes, it has two calibrations. For zeroing and second for fine tuning by using known accurate calibrating resistance of few ohms

 

should be looking at an LCR meter.

I have dedicated Capacitance meter up to 20000 µF

You may want to consider my other design:

Nope I did not know of it. But i know now  It looks very linear and again simple enough .

***
That is the deal, folks .. The circuit is not good from 9 volt battery. When turned on it displays the usual (-1***) but after half of second the digits start go all over the place. After scoping found that the voltage is dropping to around 7 on the battery itself and 3.9 volts for the 5 volt digital stuffs. I have shunted the safety diode for additional 0.7 volts but it is not enough.
The drive signal is good, op amps are working nice.

[jaxbird]

I did a digital version of Jay_Diddy_B's 5 Transistor ESR Meter some years ago and I still use it today to check for bad caps in circuit.

However it appears all the details (images) are gone: https://www.eevblog.com/forum/projects/esr-meter-build/