How to make a simple touch sensor

Touch Sensor Circuit DiagramYou only need 3 components.

A transistor, a resistor and an LED.

Connect the resistor and LED in series from the positive supply to the collector of the transistor. Choose a resistor that sets the current of your LED to around 20 mA.

Connect the emitter of the transistor to the negative terminal of the supply.

Now, create two wires with exposed ends – so you can see the metal.

One goes to the positive supply. The other goes to the base of the transistor.

This is all it takes.

Now, try to touch these two wires with your finger – and the LED lights up!

The reason is that your finger acts as a resistor and will give enough current to the base of the transistor to turn it on.

This is one of the circuits you will build in «Getting Started With Electronics». Along with other fun and simple circuits, to get you started in electronics. Get it here:

Keep on Soldering!

This tool has helped me many times

Oscilloscope settings knobsBut how do you learn it?

Back in the 90’s, my dad brought home an oscilloscope.

He knew I was getting more and more interested in electronics – so he borrowed an old oscilloscope from his workplace. Maybe it was from the 80’s, and it had lots of buttons with strange names on them.

An oscilloscope is an instrument that lets you look at how signals behave over time. [Read more…]