Hello,
I have made a transimpedance amplifier circuit to measure the current going through a transistor, based on a TL082. I have a 100mV power supply going to the transistor's source and the transistor's drain going to the inverting input of the TL082. There is a 10k resistor in series with the inverting input and the output, and the non-inverting input is set to ground. The TL082 has a +9v and -9v power supply on the respective leads, with the 0V between them grounded.
Occasionally, a large voltage shorts through to both the transistor's source and drain and into the opamp, frying it. I was wondering what a good approach would be to limit the voltage going into the opamp, while not causing issues with current measurement. I have already tried a 12V Zener diode with the cathode attached to the transistor's drain and the anode attached to ground, and a 10 ohm resistor from the transistor's drain to the opamp's input. I was hoping that any high voltage would cause avalanche breakdown of the Zener, redirecting all high voltages to ground, but this apparently does not work.
