Servo Motor Controller Circuit - ElectroSchematics This is the simple basic design of servo motor controller with pulse generator. It uses the CMOS IC 7555 in the Astable mode to generate pulses to drive the servo motor. The circuit can be suitably modified to get pulses of sufficient length. A Servo is a small device that has an output shaft. How do you build a simple circuit to control a servo So some sort of electronic circuit is needed to drive a servo. But this creates a complication for anyone building something from scratch. If you want to see if a car of your own design will steer properly, it would be useful to have a simple circuit that allows you to control the servo and put it through its paces.