The system shown consists of the HA-2542, a small 12-Vdc motor, and a position encoder. During operation, the encode
r causes a series of "constant-width" pulses to charge CI. The integrated pulses develop a reference voltage, which is proportional to motor speed and is applied to the inverting input of HA-2542. The noninverting input is held at a constant voltage, which represents the desired motor speed. A difference between these two inputs will send a corrected drive signal to the motor, which completes the speed control system loop.