Dear NI forum, I have a setup (shown below) which is meant to read voltage between a capacitor and resistor in series. Unfortunately I find that the capacitor is unable to fully charge with the DAQ input connected. However, If I remove AI0 connection from the circuit then the capacitor charges normally...
I'd be grateful if anyone could explain to me:
- Why this happens
- If there's a way to modify my test circuit to be able to fully charge the capacitor while DAQ is connected
For reference, I've tried switching the position of resistor and capacitor (i.e. putting the capacitor first in series) and in that case the capacitor had no problem charging. But for my application I will need to test with resistor first in series because I already have a lot of test boards that are built this way.
The power supply is configured to provide 75V (the rated voltage of the capacitor) when switched on, and current limit is set to 20mA. With those settings my capacitor only will charge to about 20 or 30 V with DAQ in the circuit.
Let me know if I can provide any other details, and thanks in advance to those who give thought to my question,