Manual Stepper Motor Controller
Approx construction cost US$16
Illustrates how a 4-phase stepper motor can be controlled bi-directionally using a conventional rotary switch
A high school student recently contacted the author for help in building a robotic arm for a school project. He had some stepper motors on hand, and was looking for a simple way to utilize them. Unfortunately there didn't seem to be any really simple way to do it - nor could the author find any published design to help - at least not any that fitted the description of "simplicity itself".
A typical stepper motor control system incorporates a microprocessor control unit, a drive card, and a dedicated power supply unit - as well as, of course, the motor itself. The author perceived in this a basic problem. The barrier between owning a stepper motor and actually using it is fairly great. Contrast this with the easy availability of stepper motors today, particularly from cast-off 5žin. disk drives and fax machines, and you clearly have a problem waiting for a solution.
This project describes a simple way to rotate a four-phase unipolar stepper motor with the help of a single rotary switch, just eight inexpensive rectifier diodes, and some incidental components.
More details on this construction project can be found in the April 2002 issue of EPE Online, the world's first web-delivered electronics and computing hobbyist magazine.
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