A high impedance input and low voltage voltmeter is shown in figure 1.
Formula
High Impedance Voltimeter:
Im = Vin / R1
Where:
Im is the current flowing through the meter in amperes (A)
Vin is the input voltage in volts (V)
R1 is the resistance in ohm (Ω)
Note: R2 is the current limiting resistor and is chosen according the meter.
