2THE TOUCH-ENABLED LIGHT
LIGHT UP AN LED WHEN YOU TOUCH A TOUCHPAD MADE FROM TWO UNINSULATED WIRES.
THE CIRCUIT DIAGRAM
THE PARTS LIST
PART |
VALUE |
DESCRIPTION |
R1 |
470 Ω |
Standard resistor |
LED |
Red/yellow/green |
Standard-output light-emitting diode |
Q1 |
BC547 |
General-purpose NPN transistor |
INTRODUCING THE TRANSISTOR
In this circuit, you’ll use a transistor—specifically, an NPN transistor. It has three pins:
- Top pin: Collector
- Middle pin: Base
- Bottom pin: Emitter
Don’t worry about the meaning of the pin names—just think of them as labels. ...
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