The Servo Motor Tester can be used to manually operate a servo motor clockwise and anti-clockwise direction. By pushing the forward or reverse button for a short period of time you can control the rotation of the servo. It will also test a servo. A Servo is a small device that has an output shaft. This shaft can be positioned to specific angular positions by sending the servo a coded signal. As long as the coded signal exists on the input line, the servo will maintain the angular position of the shaft. The angular position of the shaft is determined by the duration of a pulse that is applied to the control wire. This is called Pulse Coded Modulation.

In the Servo Motor Tester when using a servo motor in if it does not respond as per the input, how to make sure that the fault is not in the servo motor but the circuit or logic One way is to isolate the servo motor from the circuit and check its proper working by feeding it pulses of varying width and checking the angle that the servo motor turns to. Hear a 555 timer IC use to operate the servo motor. The circuit is designed to give control signals to the Servo. The LM555 timer IC is designed as an Astable multi vibrator which can give pulses for the operation of the Servo. BC547 is used here to amplify the signal of timer IC, as the current required by the servo motor is large