This is a 3AMP DC Motor speed and direction controller using MC33035 IC from on semiconductor, though the MC33035 was designed to control brushless DC motor , it may also be used to control DC brush type motors. MC33035 driving a Mosfets based H-Bridge affording minimal parts count to operate a brush type motor. On board potentiometer provided for speed control, slide switch for direction control and brake, On board jumper available to enable the chip. The controller function in normal manner with a PWM frequency of approximately 25Khz. Motor speed is controlled by adjusting the voltage presented to the non inverting input of the error amplifier establishing the PWM’s slice or reference level. Cycle by cycle current limiting of the motor is accomplished by sensing the voltage across the shunt resistor to the ground of H-bridge. The overcurrent sense circuit makes it possible to reverse the direction of the motor, using normal forward/reverse switch, on the fly and not have to completely stop it before reversing.
DC Motor & Direction Controller with Brake using MC33035 – [Link]