An LED can be used as a simple stepper motor continuity tester. Motors act as generators when driven and a typical stepper motor will generate a low voltage / low current output when spun by hand. This is enough to light an LED.
The technique can be used to figure out motor winding pairs and continuity.
Other methods of checking windings are:
- Short one winding. (In the video example that would require replacing the LED with a link.) You should feel a very marked increase in resistance to rotation and feel “cogging” as each tooth of the rotor passes a pole. Repeat for the other winding.
- Use a multimeter. This will be more useful than the video LED test in identifying the windings in, for example, centre-tapped uni-polar motors as each coil’s end to end resistance will be double that of centre to end resistance. It also allows comparison between windings.
