A little bigger than a postage stamp, the Simple Servo Tester lets you control two digital or analog servos without using a transmitter or receiver, just plug in your battery pack to start testing.
Use it to check your servos before installing them into your models or to center your servos when setting up linkages. The Simple Servo Tester can also be tuned to precisely center your servos – Some manufactures consider 1.520 milliseconds to be center while others use 1.500 milliseconds.
Use it anytime you want to operate a servo but don’t want to get out your RC equipment!
This project was designed by W9GFO. You can get the kit from Gadget Gangster and download a PDF version of this howto.
Warm up your soldering iron and get started!
For more detail: Simple Servo Tester