touch switch circuit diagram

Posted on Feb 6, 2014

When the water is empty the wires in the tank are open circuited and the 180K resistors pulls the switch low hence opening the switch and LEDs are OFF. As the water starts filling up, first the wire in the tank connected to S1 and the + supply are shorted by water. This closes the switch S1 and turns the LED1 ON. As the water continues to fill the

touch switch circuit diagram
Click here to download the full size of the above Circuit.

tank, the LEDs2, 3 and 4 light up gradually. When the water is full, the base of the transistor BC148 is pulled high by the water and this saturates the transistor, turning the buzzer ON. The SPST switch has to be opened to turn the buzzer OFF.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Voltage Inverter II
    5-Band Graphic Equalizer with LA3600
    220V 200W Bulb flasher
    fire alarm circuit with temperature
    Simple Metal Detector Circuit
    Decreasing intermod on the Kenwood TM-733 receivers
    MC1411 series Darlington current internal structure of a drive circuit
    Door light emitting logic circuit with CD4069