Introduction: Simple Touch Switch 3904 NPN
This project will show you how to make a simple touch switch using a 2N3904 (NPN) transistor.
A newbie special 10 minutes project!
Step 1: Parts List:
- 1 LED
- 1 2N3904 Transistor
- Jumper Wires
- 2 680 Ohm Resistors *or 1K or less
- Breadboard or PCB w/solder
- 5V Power Supply
Step 2: Connecting the Transistor
- Place the 2N3904 transistor on the breadboard with the flat side facing you.
- Connect a resistor from the right >>>>> most pin of the 2N3904 to the (+) short leg of the LED.
- Connect the (-) long leg of the LED to ground.
- Place a jumper wire in a spare slot where you placed your resistor.
- Connect the 2nd resistor to the left <<<<< most 2N3904 pin, power (5V) the other end of the resistor.
- Place a jumper wire in a spare slot where the left most <<<< pin of the 2N3904 is connected.
Step 3: Test the Circuit
Now that all the parts are connected test the circuit by simply tapping the wires together.
Did it work? YAY!!! Now try touching a wire with your left hand and touching the other wire with your right hand.
You can even have a friend join in, just hold hands and complete the circuit. The current travels through your body completing the circuit and lites the LED. Cool huh?
Step 4: Watch Me Build the Project!
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