In this project guide, we’re building a Touch Switch Circuit using NE 555 IC. As you know, NE/SE 555 is a very popular timer IC with multiple applications in different projects. A touch switch is basically a simple switching circuit activated upon a touch. If you’re new to 555 IC, please take the time to read our beginner’s guide on 555 IC. Also, you can try many of our applications using 555 timer IC

### 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 then turns off automatically.

This circuit is realized by utilizing the high input impedance of the trigger pin of the 555 IC. When the IC is triggered by the induced voltage of the 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 set up the circuit connects to the power supply and adjust R1 while keeping touching on the touch plate. Stop at the point where relay activates. If the relay is in the activated state initially then do the same until the relay is deactivated.

### Touch Switch Circuit Diagram

1. priyanka sivam

sir,I’m not understand concept of touch switch circuit,plz kindly send information of touch switch circuit as soon as possible sir.

2. VISWINI.A

SIR, I WANT MINIPROJECT CIRCUITS FOR ECE WITH COMPLETE EXPLANATION AND CIRCUIT DIAGRAM WHICH ARE MODERATELY COMPLEX.PLEASE HELP ME………

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

• Seetharaman

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.

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

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

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

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

thanking you

6. udbhav mishra

thanking u bye

7. Sipiriansimpo

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

8. 5M pot is not available in the store. then which pot is used? led where connected? PLEAS replay.

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

ground should be connected to the point marked with the ground symbol, a positive should be connected to the point marked 12V DC

• 5M ohm pot is not available in the store. led where connected.

• You mean indication LED? It can be connected to the O/P of the relay terminals

10. Alfonzo Manjarres

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?

11. 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

12. sugiman/the-g-man

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

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

14. 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!

15. how it works?

where should i touch it?

only in the plate?

or plate and the ground

16. confused…

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?

17. blwngazkit

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)

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

19. twits4twats

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.

20. Jules Moretti

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?