How to build touch sensor circuit.pptx

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1. How to build touch sensor circuit Circuit Components Needed How it works How to build

2. Circuit Diagram

3. Components needed 9V Battery 9V Battery Clip Breadboard Jumper Wires 470Ω Resistor Red LED NPN Transistor (BC546/547/548 or similar)

4. How it works Your body has electric resistance. You can check by measuring the resistance between your fingers with a  multimeter . So when you touch the wires of the touchpad, your body behaves as a resistor. This means a small amount of current can flow from the plus of the battery, through the transistor’s base, and turn on the transistor. When the transistor is on, current can flow from collector to emitter of the transistor and the LED will turn on.

5. How to build the circuit Connect the transistor on the breadboard

6. Connect the resistor

7. Place the LED & Touchpad

8. Connect the Touchpad

9. Touch it!

10. Result You will see the LED glowing If you can’t see the light, try making the tip of your finger wet before touching again. When the skin of your finger is wet, the resistance decreases so that more current can flow through your finger and to the base of the transistor.