9203 Common Mode

[Hiemstra]

Hello,

I am trying to measure a small current (a few micro amps) with the NI 9203 in at a large AC potential (50Vrms @ 100 Hz).

In my results I find a current of about 4-5 micro amps oscillating with 100Hz and shaped like the time derivative of the applied Voltage

when no current is expected. If I increase the Voltage this current doubles in size.

I expect I am working on the limits of the amplifier, however I can't find the CMRR or the common mode voltage range in the data sheet or specs of the NI 9203,

can you help me get this data?

Thanks.

[LoCa]

Hello Hiemstra,

first of all, a few micro amps are lower than the accuracy of the 9203 (0,049mA).

You find the Limits of the Inputs in the specification -> follow this link

https://www.ni.com/docs/en-US/bundle/ni-9203-specs/page/specs.html

or at the picture in the attachments.

I hope this Information help you further.

Best Regards

Lorenz Casper