Touch Switch Circuit

Touch Switch Circuit using NE 555

Description

This is the circuit diagram of a small touch plate controller using IC NE 555 .This circuit is ideally useful for making touch operated doorbells, buzzers,toys etc which when touched on the touch plate operates the relay for a preset time and the turns off automatically.

This circuit is realized by utilizing the high input impedance of trigger pin of the 555 IC.When  the IC is triggered by the induced voltage of human body the output goes high for a time determined by R1 and C1.The transistor is used to drive the relay.The relay contacts can be used to drive the load like bell, motor , lights etc.

Notes.

To make the touch plate cut a 1 square cm thin metal sheet.

To setup the circuit connect to power supply and  adjust R1 while keeping touching on the touch plate.Stop at the point where relay activates.If relay is in the activated state initially then do the same until the relay is deactivated.

Touch Switch Circuit Diagram

touch switch circuit

 

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31 Responses to “Touch Switch Circuit”

  • atanu says:

    Please suggest me the function of potentiometer……… And what occur if I don’t use that………. Am I use 5m register…..
    Reply

    • Seetharaman says:

      5 mega ohms potentiometer is used as a variable resistance (rheostat). Its value decides the on time duration of the load. 4.7 mega ohms present pots are available van be used.

  • atanu says:

    How to connect pot…… Don’t understand the pin…… 5m pot unavailable in market….. Please give a supplement…… Please Please

    • vasudev says:

      the middle pin is the no-3 pin,pots do not have polarity so you can connect in any way

    • atanu says:

      Please suggest me the function of potentiometer……… And what occur if I don’t use that………. Am I use 5m register…..

  • dip says:

    sir i want pcb lAYOUT… plz kindly send this

  • vasu says:

    dear sir we want touch switch circuit,we r using this circuit elevator panel(switchs)

    please sir
    thanking you

  • udbhav mishra says:

    sir please help me in making touch switch please send some information at my e mail its urgent
    thanking u bye

  • Sir, can the touch sensor circuit be used as door knob alarm?

  • mahen says:

    I want project report of this project in detail!

  • mahen says:

    I what project report of this project in detail!

  • mahen says:

    I project report of this project in detail!

  • mahen says:

    5M pot is not available in the store. then which pot is used? led where connected? PLEAS replay.

  • mahen says:

    where ground is connect? where positive terminal is connect? pleas replay ….

  • Alfonzo Manjarres says:

    Style and Sound not sure about this particular style choice, but I love the idea of customizing one’s case.  Does flat black spray paint count?

  • RICK says:

    This Circuit is not BAD,,,, but it does WORK!!!! Thanks John—-It WORKS,,I Tried it out with a LED and a series resistor connected between pin#3 and 12Vdc

  • amjaad says:

    its a very bade touch switch circuit

  • for admin or mr seetharaman. please tell me, how its work. if i use this to be a secret switch for motor cycle, will it stay on? after i touch it until i touch again. or it’ll automaticaly off after a few minutes after 1st touching? how can i lock it until 2nd touch for turn it off? thanks

  • vijay says:

    i like this circuit i have to do a b.tech project in this touch plate switch…………..

  • Keith says:

    Hello. I am looking for a way to adapt a wireless door bell transmitter with a push button to a touch sensitive switch. I am not familiar with electornic circuits, but it looks like this would be something I can use. My question is, does this circuit use quite a bit of power from that 12V battery (even when it is not being touched)? How long can a 12V battery last hooked to a circuit like this? And lastly, are there parts like this on the market? Thank you!

  • jhapet says:

    how it works?

    where should i touch it?

    only in the plate?

    or plate and the ground

  • confused... says:

    Wouldn’t a capacitor installed between pin 2 and +12VDC result in a constant on as it would send a trigger voltage to the timer?

  • blwngazkit says:

    If I’m not mistaken, the 5M Pot, even at half value when coupled with a 100uF Cap will result in an ON time of several hundred seconds. Was/is that the intent?

    T = 1.1 * (5×10^6) * (100×10^-6)
    T = 550 seconds (9.1 minutes)

  • yao says:

    kind of you, i realised this diagram but as twits4twats said, without this aditionnal capacitor, the result is not correct; thank you

  • twits4twats says:

    The “Touch Switch Circuit using NE 555″ above works. Only one small issue with it though. A 100pF – 300pF ceramic capacitor should be installed between pin 2 and 12VDC to eliminate any electrical interference caused from electrical devices turned on and off. If you don’t install this capacitor, the circuit activates radomly giving the impression that it is faulty.This value can be altered through trial and error to see what works but stick between these values and you should be ok.

    A suggestion if the circuit is to be used in a battery operated application. Depending on what load you are switching, leave the relay out and select a higher spec transistor. This way the current consumption is restricted saving your battery life.

  • Jules Moretti says:

    Dear John,

    Very nice Circuit, I was wondering if you could help me out as I am trying to find a circuit that is touch sensitive like yours that is also 12VDC powered but that when triggered it dims light on and when touched again dims light down.

    do you know of any circuits that can do this?

    Thanking you in advance.

    Jules