Non-Microcontroller Servo Driver - Using discrete components
[Issue 57] A servo driver project using 555 timers and discrete components, without the need for a microcontroller.
There was a time, not too long ago, when microcontrollers were not so easily accessible to the average maker. Coding languages were more complex and less well-known outside engineering circles and like-minded people. Microcontrollers themselves were more complex, far harder to program than the bootloader-equipped versions of today. In addition, they were often quite expensive and less accessible in the domestic market.
Servos themselves have been used in radio control and model railway hobbies for decades, even without microcontrollers. The operating principle has not changed, either. The basic premise is to feed a rectangular wave of fixed frequency to the servo’s control circuit. The width of the high pulse determines the angle of the servo via an internal feedback circuit connected to a potentiometer on the base of the servo output shaft.
Our non-microcontroller solution uses two NE555 timers. The first establishes an astable pulse train of consistent frequency, which feeds a monostable circuit to deliver the desired pulse width, which can be adjusted with no possibility of affecting the frequency. In addition, the frequency can be adjusted with no effect on the pulse width.
The output from the monostable circuit can directly drive a servo signal pin.
We provide two separate options. Potentiometer-follower and switched. You can adapt these circuits to meet your needs.
Read all about the project on page 42 of Issue 57 or visit https://diyode.io/057qdpj