Hi,
Present setup: I have an experiment that requires high electrical shielding, that has an output (two pins) from an electrometer op-amp (INA116PA), that will go through a very small pin hole in the metal chassis. The output is DC voltage anywhere from 0.1mV to a few volts, although it would cool to see less than 0.1mV. The entire experiment is DC. I use a normal DMM connected to the output of the chassis, but this requires the DMM to be inside a shield, so I just place everything inside a microwave oven and view the DMM through the oven door. This works great, but lugging around a microwave oven is not so mobile, and doesn't look so pretty. The input wires that go through the chassis pin holes cannot allow any appreciable external noise to enter into the chassis, and should be less than 100uV rms, preferably a lot less.
New setup idea: So, earlier today the idea was to get a 4.5 digit ADC chip and an LCD display, all just outside the chassis that connects to the electrometer output via the small chassis pin hole. That should work since the ADC input pins are very close to each other and probably would not produce much external noise into the chassis. Perhaps a small cap could be placed on the output pins on the outside of the chassis. I wanted to stay away from magnetic filter beads on the input wires because that would setup resonance with capacitance. Do you think this method would shield external noise well enough without the need of the microwave oven?
Any other idea? I thought about getting a small DMM that the proper input connector well suited for noise, but don't know of any.
Regards, Paul