12V DC Motor Speed Control Circuit Diagram

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The simplest 12V DC motor speed control circuit diagram implies a single potentiometer. However, this is not an efficient way of controlling the speed of a 12V DC motor. The best way to control the motor speed is using a PWM.

12V DC Motor Speed Control Circuit Diagram

PWM circuits are simple oscillators which are capable to efficiently control the DC motor speed by closing and opening the circuit repeatedly, over and over. With a PWM circuit you will supply to your motor a fixed pulsed voltage.

The 555 IC is one of the simplest timers wide spread for it’s cheap price and almost unlimited options.

One application of the 555 timer Integrated Circuit is the 12V DC motor speed control. The circuit diagram for this motor speed controller is very simple and can be built in air without a PCB.

12V DC motor speed control circuit diagram with 555 timer IC

By using the above 12V DC motor speed control circuit diagram you will have a speed control between 5% and 95%. By the variation the voltage straight using a potentiometer, this extended speed range would be impossible.

The MosFet will be limiting the current through the DC motor. You will have to pick one MosFet to fit your engine’s power requirement. In case of high amperage you should place a radiator on it.

The diode placed on the motor will help protect the PWM circuit the resistive inductance of the DC motor. This is the high current rectifier diode from our bill of materials.

The list of materials needed for 12V DC motor speed control circuit diagram:

  • 1 555 timer Integrated Circuit
  • 1 high current rectifier diode
  • 2 low current rectifier diodes
  • 1 variable resistor (potentiometer) max 1 Mega ohm
  • 1 low power 1 Kilo Ohm resistor
  • 2 electrolytic capacitors 0.1 micro Farad
  • 1 electrolytic capacitor 470 micro Farad
  • 1 power MosFet

Don’t forget the DC motor.

This is a simple 12V DC motor speed control circuit diagram using a 555 timer IC in astable mode. This PWM circuit is the very basic PWM DC motor speed controller.

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