Transistors as Electronic Switches

Introduction

Transistors are the building blocks of modern electronics. While they can amplify signals, their most common use in DIY projects is as a switch.

NPN Switching Circuit

To control a 12V motor from a 5V Arduino:

1. Base: Connect to Arduino pin through a 1kΩ resistor.
2. Collector: Connect to the negative terminal of the motor.
3. Emitter: Connect to Ground (GND).

Why Use a Transistor?

Microcontrollers can only output about 20-40mA. A transistor like the 2N2222 or TIP120 can switch much higher currents (up to several Amps).