[volt-nuts] nA advice

[Andrea Baldoni]

Hello!

I would like to measure insulation resistance of some defective load cells.
The measurement should be done with no more than 50V and the full scale
reading should be >=5Gohm. Accuracy of +-10% is enough (in fact it could
suffice just to check if it's >=5Gohm or not).

I have not been able to find a ready made instrument that could do this within
a reasonable price (100 EUR); the normal insulation resistance testers go much
high with the probing voltage (on the purpose, but this also lighten much the
requirements on the sensitivity of the meter).

It could be as simple as a led indicator "pass/fail", but at this point, why
not to build a good frontend for a multimeter, so it could be much more useful?

There are many way to do this and also many ready circuits (like the
null detector in the mini metrology lab by Conrad Hoffmann) or in the AoE,
but instead of making it from scratch, someone knows if there is something
already made (or a kit)?

Best regards
Andrea Baldoni