J-FET based high-impedance voltage meter

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01:26:21

Voltmeter circuit consists of input voltage divider (switched to 1:1 by default) and microammeter connected to the diagonal of the ((initially balanced) bridge formed by a pair of JFETs (each of them emulated by MOSFET, Vsource and 100M resistors) and a pair of 1.2K resistors. 300 Ohm resistor emulates the microammeter resistance with connected in series CCVS just doing the right scaling for proper measument indications. Green plot is the input signal, blue is the voltmeter indication. As you can see measured value does not exactly follow to the input one due to some delay. Use (left-bottom) switch to choose another source which voltage changes slowly. (for the last case measured and input values are almost coincide)

published 1 year ago

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