This is a circuit of the open loop PWM controller using the NE5560. This controller is suitable for Switched mode motor drive. To get the best dynamic response, the switched-mode controller must be set consider to the motor electrical time constant and starting current. The motor has a peak current that must be carried by the transistor. Here is the schematic diagram of the circuit:

THE OPEN LOOP PWM CONTROLLER USING THE NE5560 FOR SWITCHED MODE MOTOR DRIVE SMMD  circuit schematic

If the voltage above 50V is to  be switched to the motor, the circuit must be added with diode transient suppressors and snubber networks to protect this device. Because of its very low drive current, the new power MOS FETs is used in many DC drive designs. An internal intrinsic diode give a protection from reverse transients. If more power handling capability is needed, just parallel these devices. [Circuit’s Schematic Diagram Source: Philips  Semiconductors Application Note]