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Transistor Touch Switch Simple Science Project Parts List

Parts list for the simple transistor touch switch

This project is the simplest touch switch circuit that I could come up with. It has the bare minimum number of parts but it still manages to work well.

Solderless BreadBoard
830 tie-points

This is the breadboard that I used because I happen to have several of them. I find that they are a good general size for making small circuits and they snap together when more breadboard area is required.


No matter what projects you decide to build in the future you will need resistors. Having a handy stock of different value components on hand can prove very useful.

I used two 470Ω resistors in this project but you could use any value between 100Ω and 1kΩ if you have them handy.


Transistors are very useful. You can use them to build all manner of circuits and you will often find you need one or two even when dealing with more advanced microcontroller projects.


Any high intensity LED will do. Most LEDs available today are high intensity so it should be easy to find some.

Hookup wire

I have a reel of bare 21 AWG (22(SWG) solid copper wire which I tend to use for short hook ups. Insulated solid hook up wire will do the same job for you and you can strip the insulation off so that you can use a longer length to make the touch strip.



You can generally buy a 9v battery from almost any store. I have included it into the parts list for completeness to allow you to order everything at the same time if you wish.

Battery connector

Cheap snap on battery connectors provide an easy way to connect and disconnect power from your circuit.

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Comments (10)

Topic: Transistor Touch Switch Simple Science Project
Full StarFull StarFull StarFull StarHalf Star 4.5/5 (7)
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Chad (US) says...
Studying capacitors as well as transistors right now. Would adding one cause the light to blink?
19th February 2017 6:17pm
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divya (India) says...
what is the principal for touch switch?
17th December 2016 7:53am
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sravanthy (India) says...
can i place the same circuit on pcb
8th April 2016 5:25pm
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Jhajha Bokarowasi (India) says...
Done! Perfect. If Anyone needs help connect with me through Quora. Thanks Steve. Love you ♥
26th November 2015 10:50am
megha (India) says...
will dis be perfect???? or if possible.. can u suggest me some better topics....
23rd October 2015 7:44pm
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megha (India) says...
hey, my question is.. where can i get a complete information on this in detail... since i need to submit it for my 12th boards... pls help...
23rd October 2015 7:42pm
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sumit (Bangladesh) says...
Cryingwhich NPN transistor did i use???
5th May 2014 8:13am
Steve (UK) says...
Hi Sumit,

Any NPN from the pack listed in the parts list on page 2 of this article should do just fine.
15th May 2014 8:33am
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nisha (India) says...
its gud bt i wonder whether its useful in dae to dae life!
6th April 2014 3:12pm
Steve (UK) says...
Hi Nisha, This circuit is meant to demonstrate the use of a transistor as a switch. It can be used anywhere that a small current signal is available but it must switch a larger current. This requirement crops up every day when interfacing microprocessors with external equipment for instance. Even turning on an indicator LED from an output pin of a microcontroller is often done using a circuit like this with the output pin driving the base of the transistor. I hope that this helps you to think ... Read More
6th April 2014 3:40pm

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