How to find out whether I have a unipolar or a bipolar stepper motor?
You have a third type of motor: A "Universal" motor.

This is a motor can can be configured as either a unipolar or a bipolar motor.

General rules:


4 Wires: Bipolar only
5 Wires: Unipolar only
6 Wires: Universal
8 Wires: Universal


A unipolar only motor has the center of both windings connected together internally. This precludes the use of the motor in a bipolar system.

With a motor with six leads, if you connect the leads from the center of each winding together, you get a unipolar motor. If you leave the center connections unconnected, and drive each winding using only the connections to the winding ends, you are using it in bipolar mode.