Bidirectional DC Motor Speed Controller

This kit allows controlling the speed of a DC motor in

both the forward and reverse direction. The range of

control is from fully OFF to fully ON in both directions.

Normally, switches are used to change the direction of

rotation of a DC motor. Change the polarity of the applied

voltage and the motor spins the other way! However this

has the disadvantage that a DPDT switch has to be added

to change the polarity of the applied voltage. Now you

have two things to control the motor a direction switch

as well as the speed control.

Also, it is not a good idea to suddenly reverse the voltage

on a DC motor while it is spinning. It can cause a current

surge that can burn out the speed controller. Not to

mention any mechanical stress it can cause as well.

This kit overcomes both these problems. The direction and

speed is controlled using a single potentiometer. Turning

the pot in one direction causes the motor to start spinning.

Turning the pot in the other direction causes the motor to

spin in the opposite direction. The center position on the

pot is OFF, forcing the motor to slow and stop before

changing direction.