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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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  • Logesh

    Got it, 1M is used for 100 secs timing. More t resistance more the secs…

    Can we hook this with 12v siren straight away with out relay?

  • Logesh

    Why are we using 1M resistor… Kindly tell me pls..

    It s very interesting circuit, am going to implement this on my metal gate, and am going to use 12V DC siren.

    Kindly let me know any changes has to be done on circuit…

  • Shiva

    How much amount of relay we can use

  • Mac

    What does the size of the “touch plate” have on the sensitivity and operational reliability? I want to wire a touch sensor to my front door, which is metal… or run a wire to the door knob assembly. Has anyone tried something like that? [The object is to light a floor lamp via relay/driver, and delay-off circuitry (all of which I’ll add) when the door knob is touched.]

  • pat

    pls sir, i want to know what makes the touch not to function except i touched the negative line before touching it?

  • Yusuf

    please can the above circuit b fixed to motor car fo anti theft, if yes, hw do I fix the touch plate? you knw d body of a car is carrying negative voltage

  • Yusuf

    please can the above circuit b fixed to motor car fo anti theft, if yes, hw do I fix the touch plate? you knw d body of a car is carrying negative voltage

  • George Karitu

    Hello Rocky,
    You want a Touch circuit that can remain on for as long as you want.Yes this is possible if you let the relay operate a Digital on/off switch.Download a digital on/off switch.
    Best Regards,
    George Karitu
    Kabethi Holdings Ltd.

    • Rocky

      Hi, thanks for the reply but I am wondering what a digital on/off switch is? is that RS flip flop you are talking about or something else. please tell me ASAP I will be highly appreciate for your reply.

      Thabnks,
      Rocky

  • sj

    whats 1M???

  • dipak

    sir i want pcb layout for this.. plz kindly send this

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