DC motor Speed Control with MOSFET & Potentiometer

Here a circuit to control DC motor speed using MOSFET and Potentiometer is demonstrated. The MOSFET used is CEP7030L which is N-Channel Enhancement Mode Field Effect Transistor(MOSFET). This MOSFET transistor can be salvaged from old PC power supply units(PSU) as was done in this demonstration. Using such power MOSFET we can apply high voltage to the DC motor without heating the power MOSFET. Here the DC motor has voltage rating of 12V. The potentiometer is a 10KOhm potentiometer. An additional resistor of 1MOhm is also used. 

Watch the following video to see how the DC motor speed controller works.

The following pictures shows the speed controller setup.

DC motor control using potentiometer and mosfet

The following shows the speed controller circuit on breadboard with MOSFET and Potentiometer.

DC speed controller circuit on breadboard

The circuit was powered using 12V from bench power supply as shown below.

DC motor power supply

The circuit schematic of the DC motor speed controller using MOSFET and Potentiometer is shown below.

dc motor speed controller animation
In the circuit schematic above, 12V positive terminal is connected directly to the drain of the CEP7030L power MOSFET. One terminal of the DC motor is connected to the source of the MOSFET while the other terminal of the motor is connected back to the negative terminal of the 12V battery. The 10kOhm potentiometer middle terminal is connected to the gate of the transistor. The other two sides are connected to the positive and negative wires. Thus the potentiometer is used as a voltage divider. The 1MOhm resistor is used to bias the transistor. This was explained in the tutorial
Zero Gate Bias of Depletion MOSFET.

Here we have shown how to build a DC motor speed controller using Potentiometer and power MOSFET salvaged from PC power supply unit. One an also build simple DC motor at home and this controller can be applied also. For robotics more sophisticated motor controller such L298N IC as can be used as is demonstrated in the tutorial DC motor control using L293D Motor Shield and Arduino.

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