Here is a easy to read 'Analog' Millivoltmeter. Just like the Moving Coil Voltmeter, but does not have that resolution. This gives a easy indication of process progress or parameter magnitude from a large distance. A bargraph is easy on decision making too, compared to a digital readout.
How this Works ? - The analog input in mV - millivolts is fed to R18, RC reduces Noise and the Zener Clamps protect. The LF353 FET Opamp offers High Impedance as a Non-Inverting Amplifier, which nullifies measurement burden, Remember the Moving coil voltmeter loads the measured circuit, causing sizable errors. Then they invented the Vacuum Tube Voltmeter to solve this issue. An FET voltmeter is near ideal, they ought to have inventing this first.
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