Low-ESR analog meter

[frako]

Hello

New year and new ESR-meter. This works much better than last year version. It is not ready yet as all power supply, protection, pcb etc. is missing. Also it is quite slow.

http://koti.mbnet.fi/hsahko/elek/kv/mcpESR/

Tried to draw what I have on breadboard into schematic, there may be errors in it

[frako]

Re: Low-ESR analog meter

Finally got the PCB on friday. How many mistakes there can be in one small board...

But after some modifications it seems to be working quite ok. Some small modifications are still needed (add zero trim, change gain adjust range and I must have been half-sleeping when I put that power supply part in there)

Test leads are connected at pads marked G+/-. This version uses two-lead measurement and runs from 9V battery
Tested it with some caps and it gave following results. Results are at least in the right ballpark.
Nichicon HE 1000 μF 16 V 41,3 mΩ
Panasonic FM 470 μF 16 V 44,0 mΩ
Panasonic FC 470 μF 25 V 72,8 mΩ

[Agent24]

Re: Low-ESR analog meter

Looks nice.. like the purple PCB!

[Th3_uN1Qu3]

Re: Low-ESR analog meter

Do you still need the relative function of the DMM with this version?

[frako]

Re: Low-ESR analog meter

Looks nice.. like the purple PCB!

They are from pcb.laen.org and that is standard color....

Do you still need the relative function of the DMM with this version?

Yes, it is still needed but the offset is only about 15 mV = about equal to test lead resistance. I think I but a trimmer for zeroing that out in next version.

[Agent24]

Re: Low-ESR analog meter

They are from pcb.laen.org and that is standard color....

Ah, most people seem to just use green, or red.