Single transistor projects

Touch switch circuit by using an NPN transistor

Touch switch circuit using NPN Transistor

The touch sensor also touch-sensitive switch or touch switch circuit the current is passed our finger body and the NPN transistor is turned ON when current is passed out through our body to the base of the transistor and the LED glows.” Touch Switch Circuit “.

Step 1: Materials and the Circuit

Touch switch circuit


1. Transistor 2N2222A(NPN) -1 pcs

2.100-200ohm resistor 1/2w -1pcs

3.LED-red any color-1pcs

4.6V TO 9V POWER SUPPLY (from the battery or dc power supply, etc)

5.Some small pieces of metal sheet(for the touchpad)

The circuitry used here is having a single NPN transistor acting as a current signal amplifier so that dc could be passed through our hand or body easily from battery positive to the transistor base making it turned on(switched on) and as a result, the LED starts to glow.

The materials are listed above and also in the circuit diagram but a video can help more so I have added a video at last.


Step 2: Complete Circuit and Making the TouchPad

Touch switch circuit

>Have a look at the completed circuit, I have added the metallic strips in the form of finger touchpad. Arranged like two strips connected to one wire and other two strips to the other wire to be touched, so that when they are touched the current passed and LED glows.

Step-3: Below is the video.

I hope you guys liked it. If you liked it then comment below and let me know.

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Aabhishek Sharma is a Computer Science Engineer and a Digital Marketing Trainer and Consultant. Aabhishek Sharma also loves working on Electronics Projects and working with microcontrollers and Designing Home automation Gadgets.

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