P
Paul
Guest
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
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