Bidirectional proportional motor control circuit

Circuit working principle: The motor driver is an L2931C, which can output a current of 1A in either direction. Speed ​​and direction control can be achieved using a multivibrator with an adjustable duty cycle .
When the potentiometer is in the center, the oscillation waveform
is symmetrical and the motor stops; when the potentiometer slides to one side, a bias voltage is given in the corresponding direction
to make the motor rotate.