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555 touch sensor switch circuit schematic

Touch Sensor Switch Circuit with 555 timer

This is a very simple touch sensor switch that is build with the 555 timer IC.
You just need to touch the metal plate and the relay gets energised and is kept in this state for about 100 seconds, then is released.

This kind of sensor switch is suitable for making touch operated bells, buzzers of small toys which operate for a small time and then switch off automatically.

The input impedance of the trigger is very high and the touch sensor switch can be triggered by the voltage induced in the human body. The relay is a 12 V DC relay operating at currents less than 200 mA.

555 Touch Sensor Switch Schematic

555 touch sensor switch circuit schematic

27 Comments

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  • STEFANOS

    Hello Dear Mr P. Marian

    I’m ineresting to buid a similar circuit but with a small diference.
    Touch the plate and the relay stays energised (for as long as you want).
    Touch the plate again and the relay deenergised (for as long as you want).

    first touch – state ON
    next touch – state OFF
    next touch – ON
    next touch – OFF
    next touch – ON
    next touch – OFF
    …… and so on

    Thanks a lot for listening me.
    Best regards.

    • rex

      good day sir. have you find already a circuit that will stay on and when you touch the plate again it will turn off?. i realy need one for may bike i will use if for hazard blinking purposes. waiting for your reply sir and thanks in advance sir. from rex gerona philippines

    • rocky

      I need the circuit diagram ASAP for single touch latching switch in ne555 to stay on as much as u want not like limited time period, if anyway u can help me tht will be good ..

      Thnks in ADVANCE ..:)

    • Ie Chien

      There are already posted, but with separated on off touch plate.
      http://www.electroschematics.com/8435/on-off-touch-switch-with-555/

      Use the search in this web to see more circuits using other than 555 ic

    • Jim Keith

      I want to post a circuit for this function soon, so keep watching…

  • bilal

    i tried a breadboard prototype of above circuit but not working relay energises without touch when powered on and keeps on even when capacitor is full charges.
    Whats the matter can u help?

    • ritam-banerjee30gmail-com

      *resistor

    • ritam-banerjee30gmail-com

      Could you tell me what should I replace the 100uF capacitor with?? I m facingthe same problem. And if there is an alternative to the 10M register u have suggested.

    • Santhosh

      Know how to connect using breadboard

    • Jim Keith

      Replace the 100uF capacitor –it may be too leaky to charge.

      Also, try adding a 10M resistor between pin 2 and 12V

  • chienline

    I’ve built one linked to a 555-auto-off-blinking-led.
    I built it for my kid’s truck. I use 9V battery instead of 12V source.
    The idea is they always forget to turn off their toys, so I make one with auto off and touch sensor on instead of switch.
    But the next day, there was 5V remain in the battery.
    Maybe I should link it to another solar charged battery instead of 9V battery. Any other idea how to avoid battery drains with a touch sensor?

  • KROKKENOSTER

    Thanks as soon as my laziness get healed I want to build this and use it as an alarm

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