stepper motor output waveform

[hubble]

I have a small 12v 200 steps stepper motor. I am using it for generating an emf. What is its output emf waveform with respect to time? Is it sinusoidal or some other waveform? Also, is the waveform related to number of steps?

Thanks.

[Hero999]

I've never tried this myself but I'd suspect it's neither square nor sine. It's probably a messy waveform. The number of steps will determine the number of cycles per revolution.

[hubble]

OK. Then how can the nature of this type of unknown waveform be found? Do we need some kind of oscilloscope?

Thanks.

[Hero999]

Yes, you need an oscilloscope.

Spin the motor at a constant speed, perhaps use a drill but don't go too fast as very high voltages will be produced, and measure the waveform using an oscilloscope.