Hello, I am quite new on this forum. I am assembling an electronic circuit that can read a small current, coming from a magnetic source therefor has no power. The voltage in this circuit varies from 200mV to 2V alternating current. Once I connect my circuit to a bridge rectifier and then filter the signal with a capacitor, my readings become unstable. Can anybody help me?

 

Post the circuit and explain what do you mean that the measurements become astable.