Electronic circuits that use the 555 Timer

555 Timer Circuits

555 Timers are fun and a great way to start learning electronics

SERVO TESTER Circuit

This circuit can be used to manually turn a servo clockwise and anti-clockwise.  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.
Here is a photo of a kit from Cana Kit for  $10.00 plus postage (it is a slightly different circuit) and a motor and gearbox, commonly called a "servo." The output shaft has a disk or wheel containing holes. A linkage or push-rod is fitted to a hole and when the disk rotates, the shaft is pushed and pulled. The shaft only rotates about 180� to actuate flaps or ailerons etc.



A pot can be used to control the position of the servo by using the following circuit. It produces a positive pulse between about 0.9 milliseconds and 2.1 milliseconds. The off period between pulses is about 40 milliseconds. This can be shortened by reducing the value of the 3M3 resistor.



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