Controlling speed with PWM

A motor that can only be on or off is not that useful. We need to control the speed of a motor using code. Sometimes, we want the motor at half speed; sometimes we want it faster and sometimes slower. However, the motor is connected to a digital pin, whose value can either be maximum or nothing. How can we make this clear 1 and 0 into something in-between? With Pulse Width Modulation or PWM.

Getting ready

Following are the ingredients needed for this recipe:

  • A DC motor
  • A resistor between 220 ohm and 4,700 ohm
  • A standard NPN transistor (BC547, 2N3904, N2222A, TIP120) or a logic-level compatible MOSFET (IRF510, IRF520)
  • A standard diode (1N4148, 1N4001, 1N4007)

How to do it…

The following are the steps to control the speed of a ...

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