Motor low speed and high torque control circuit

Working principle of the circuit: This circuit uses the cooperation of the perforated disc on the motor shaft and the photointerrupter to obtain feedback pulses
proportional to the rotational speed . Because of the difference between the feedback pulse and the input frequency , a variable voltage is generated and sent to pin 3 of IC, and through the IC, a voltage signal with changing pulse width is generated to control the motor. The frequency of IC2 is determined by Rio and C4. The values ​​of filter center and C: should match the motor , and their values ​​are as shown in the figure. C, used to smooth pulses and reduce noise. In order to observe the operation of the circuit, a two-wire oscilloscope can be connected between the signal input and pin 3 of IC2.