Simple Touch LED Circuit

Thread Starter


Joined Feb 6, 2007
A long time ago I had a schematic that consisted of two transistors, 9v battery, LED, and other resistors.

I have looked hi and low and can't find it around my house and have search on the internet with a no go.

So I found this web page and was hoping that you all might help.

This this circuit I would demonstrate it to kids by having kids hold hands in a circle and also touch each end of the touch switch. If any kid let go then the LED would go off. It worked very well.

Any ideas?

Thanks in advance


Joined Jan 17, 2007
This reminds me of a prank, which one of my friends has pulled on me once. He had put on rubber boots, walked next to an unmarked electric fence and grabbed it with one hand. When grabbed it, he didn’t get shocked immediately, because the boots insulated him from the ground. Unknowingly, I walked up to him and he stretched his hand for a handshake. I stretched my hand too and got shocked the moment I touched him. I was wearing flip-flops and I had a good ground path. Of course my friend got shocked as much as I did, but the difference is that he was expecting it.


Joined Jan 28, 2005
Here is another circuit that uses a darlington-pair connection of the same two transistors to increase the input impedance of the overall circuit.