Servo input: PWM or analog

Thread Starter


Joined Jul 26, 2007
Hello all,

I am working on a "IR sensor/Schmitt Trigger" which outputs an analog signal to a Servo Motor (HS-322HD), however when plugging the servo to the Schmitt circuit it does not work

The servo seems to be wanting a PWM signal as it is going on and off in an unsteady fashion. Does this servo works with analog, if not, what would be the way to go?

The application: wave the hand at the IR sensor and have the motor turn on (a certain # of degrees) and then off.

Thanks for the help!


Joined Jul 22, 2007
Posting a circuit usually will get more response, quicker...

Servos usually need a signal between a square wave, with a pulse width between 1 and 2 ms, 1.5 ms being the middle position of the motor. The square wave is 20-50 hz, if I remember correctly. Anyway, there are several 555 based 'servo tester' circuits on the web you might be able to use with the rest of your circuit....