Abstract: In industry DC motor is widely uses for speed control and load characteristics, it's easy controllability provide effective and precise output so application of DC motor is large for commercial purpose. Speed control of DC motor is very crucial in application where required speed is precision and correcting signal representing and to operate motor at constant speed, so we used PWM method which are fulfill all requirements to speed control of DC motor. PWM based speed control system consists of electronic components (integrated circuits, Sensors etc.). In this paper, to control the speed of DC motor using Pulse Width Modulation (PWM) method. Microcontroller AT89S52 is used to generate PWM. L293D IC is used to drive the motor which is made up of two H-Bridge. 555 IC is used with opto coupler to sense the speed of DC motor. Rectifier circuit is used for power supply to circuit and motor. This paper shows that precise and accurate control of small DC motors can be done efficiently without using costly components and complicated circuit.

Keywords: DC motor, H-bridge, Pulse Width Modulation, IR sensor.