Introduction: PWM Controller Using Transistors

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When designing RC Cars, Robots or any project that makes use of a motor it is essential to have to control the speed of the motor. For this you need a PWM motor controller, there are a ton on motor controllers in the market but designing your own controller is what makes electronics fun. So this instructable I'm going to show you How to build a motor speed controller using inexpensive transistors.

Step 1: Bill of Materials

For this instructable, you will need,

  • BC557 & BC338 Transistor
  • 100 uf Capacitor 60V
  • 47Ohm Resistor
  • 22k Resistor
  • 220 Ohm resistor
  • 10k Pot

Step 2: Circuit Sketch

The circuit to design the speed controller is very simple you can build the circuit up easily on a breadboard. This circuit gives the motors a series of pulses whose width determines the speed at which the motor runs. This circuit is designed for 3V motors.

Step 3: Controlling the Speed

To Control the speed of the motor you need to vary the 10k variable resistor, this should vary the pulse width sizes and thereby should either increase the motor speed or decrease the motor speed based on the turning direction of the variable resistor.

Going Further...

Now that you have your circuit ready it is time to implement it into a breadboard and add along with a few extra sensors or components for your next project. This circuit is only capable of driving 3V motors, so in a future Instructable, I will show you how to work with controlling higher power motors.

If you have any queries, feel free to leave a comment below or PM me and I would try to help you.

Step 4: