FET Buffered Analog Voltmeter

This is a voltmeter circuit that use FET as the buffer to improve the input impedance. This circuit uses A2N3819 FET which provides a solid-state VOM. Beside that, a cathode follower in a VOM of this circuit is The 2N3819. The calibration of this circuit is done by adjusting R12 (scale/sensitivity) and R14 (zero offset).  Since FET has very high […]

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DC, RMS, And Peak-to-Peak High Impedance Voltmeter

Analog meter normally doesn’t have high impedance since they don’t have buffer circuit inside. With active buffering, the input impedance of this circuit depends on the impedance of the op-amp. You can use other op-amp for higher impedance, but a low-cost 741 is enough for may application. The rectification inside the feedback loop path remove the effect of diode’s voltage […]

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