Capacitive Sensor

Posted on Feb 4, 2014

Q1, Q2 & Q3 form a high impedance super-Darlington that drives the relay, amplifying the 50 or 60Hz alternate mains-supply frequency induced in the sensor by the human body. C1, D2 & D3 ensure a clean switching of the relay. Power supply can be any commercial wall plug-in transformer adapter with rectifier and smoothing capacitor, capable of suppl

Capacitive Sensor
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ying the voltage and current necessary to power the relay you intend to use. * For proper operation, circuit ground must be connected via a small value, high voltage-rating capacitor to one side of the mains supply socket. The "Live" side is the right one.

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