03
beginner+200 XP

Transistor Motor Switch

Use a transistor as an electronic switch to control a motor.

🎯 Objective

Use an NPN transistor to switch a DC motor on and off with a small control signal.

📖 Background Theory

An Arduino or logic gate can only supply ~40mA from a digital pin — not enough for a motor that might need 500mA+. **The transistor as a switch:** A small current (5–10mA) at the Base controls a large current (up to 1A) between Collector and Emitter. This makes the transistor act as an amplifier or electronic relay. **NPN switching circuit:** - Emitter → GND - Motor between VCC and Collector - Base → current-limiting resistor (1kΩ) → control signal - Flyback diode across motor (prevents voltage spikes when motor turns off)

🔧 Components You'll Use

BatteryNpn TransistorDc MotorDiodeResistorGround

📋 Steps (7)

  1. 1Place Battery, NPN Transistor, DC Motor, Diode, two Resistors, and Ground
  2. 2Wire Motor from Battery + to Transistor Collector
  3. 3Wire Transistor Emitter to Ground
  4. 4Wire 1kΩ resistor from Base to your control signal (Battery + for always-on test)
  5. 5Wire Diode across motor (cathode to VCC side)
  6. 6Wire Battery – to Ground
  7. 7Run simulation and watch the motor spin!