Line-hum-touch-switch


Posted on Jan 3, 2013

The monostable period is set for about 1 second, as is the usual case. The induced line hum comes through C2, providing a continuous string of trigger pulses. The output becomes low for about 10 ms per second as the monostable times out and then retriggers. Diode D1 and capacitor C3 buffer the relay so it doesn`t chatter on those 10-ms pulses. Resistor R2 sets the sensitivity.


Line-hum-touch-switch
Click here to download the full size of the above Circuit.

The relay energizes when the plate is touched and de-energizes, up to one second after the finger is removed. The delay is a function of when the monostable last retriggered.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Hall effect sensor as Toilet Tank Refiller
    20 Watts Car Stereo Amplifier Using TDA2004
    Pong Game Console
    build lithium ion battery
    CF5019 High-Frequency 3rd Overtone Crystal Oscillator Module ICs
    light flasher/blinker circuit diagram
    touch free timer switch circuit
    Intermittent start and stop cycle control circuit Five of a
    LM4561 LM4562 consisting of 170W power amplifier circuit
    Ultra High Sensitivity Metal Detector Circuit



    Top