How to build the simplest DC Motor Speed Controller(Using Potentiometer and MOSFET)Updated
PLEASE FOLLOW THIS UPDATED VERSION:
Connect a heatsink to the MOSFET
POT can also be used to directly control a motor. But it needs to be a high power POT (unless the motor is really low power)
This circuit is very inefficient(but its really simple!) in controlling high power(torque) motors. To control such motor you're better off with PWM. PWM is much more efficient.
Here's a video showing how to build PWM speed control
Please comment if you tried building this circuit !! and hit like if you liked and dislike if you didn't like this video.
Refer the "Connections Diagram" frame in the video for connections.
This the simplest way to control the speed of a "normal" DC motor.
The variable resistor(Potentiometer,"POT") controls the voltage at the gate. The voltage at gate with reference to source(Vgs) determines the current flow through the motor. When the Vgs reaches around 2v the channels starts to open, as we keep increasing Vgs ,the channel becomes wider allowing greater current to flow. At Vgs=4v the gate opens completely and MOSFET acts a short circuit(almost short). A higher voltage at the gate leads to a higher current flow through the motor and vice versa.