Vex Servo Motor

Vex servo motors have a lot of good features. They are compact, powerful, and easy to mount and connect to things like gear shafts, beams, levers. I’ve been using micro controllers to operate these in previous projects, but decided to go old school and use a 555 timer. I really just want to do something to try out my new USB oscilloscope. I found this page with a couple of good plans.

wolfstone.halloweenhost.com

Breadboarding this was fairly easy and took just a few minutes.  I keep a lot of components around with breadboard wire already soldered, so that makes prototyping a lot faster.

Before I attached the motor, I verified that the circuit was performing as needed.  With the oscilloscope set to show 5 ms per division I could measure the minimum pulse width of 1.15 ms and a maximum width of 2.75 ms.

This seemed good enough to try, so I plugged in the motor.  The black wire is ground, the red (or orange) wire is positive, and the white wire is the signal (pin 3 on the 555).    I had nearly the full 100 degree rotation in the motor as I turned to potentiometer shaft back and forth from minimum to maximum.

Just for fun, I substituted a flex sensor for the potentiometer.  Not quite the same amount of rotation, but, I didn’t bother changing any other component values.

Servo Motor with Flex Sensor from Patrick Lewis on Vimeo.