Stepper Motors. Any Experts?

[duke37]

The resistance of the motor could be much less than 113ohm. The output depends on the voltage (118V pk-pk) and the resitance and inductance in series. Car alternators have a leakage inductance built into then so that they will current limit.
The voltage will be propotional to speed and the reactance will be proportional to frequency (speed) so the current is limited at a similar value irrespective of speed.

It should be possible to find the resistance and inductance by measurements at different speeds, try zero speed to start.

 

[MadMechanic]

Interesting, I have been looking at steppers on ebay, I think I will buy a few cheap ones and do some testing. I've been trying to figure out bipolar and unipolar wiring of these across a voltage doubler circuit. I think I am just going to build everything so that I have my dropped DC values and see what I can read. Anyone know a good way to rig up a tachometer? I know they exist for R/c airplane motors and read from the motors leads, however the tachometer would have to be calibrated for said motor. Ive also seen the handheld laser ones, I just need a way to measure rpm if I wanna be scientific about it.