STEPPER MOTOR EXPERIMENT
Stepper motors are most commonly controlled by microprocessors or custom controller ICs and the current is often switched by stepper motor drive ICs or power transistors. Precise motion is possible but the complexity usually lands the hobbyist’s stepper motors in the "maybe someday" parts bin. But steppers may be used for a variety of applications without complex circuitry or programming.
At first glance the stepping motor looks a bit intimidating since there are at least four wires and often there are six. Most steppers have two independent windings and some are center-tapped, hence the four or six wires. A quick ohmmeter check will determine which wires belong together and the center-tap may be identified by measuring the resistance between the wires; the center-tap will measure 1/2 the total winding resistance to either end of the coil. Tie the wires that belong together in a knot and tie another knot in the center-tap wire for easy identification later.
Stepper motors have become quite abundant and are available in all shapes and sizes from many surplus dealers. Experimenters can also salvage excellent steppers from old office and computer equipment.