Quote Originally Posted by Mad Professor View Post
I am using Astrosyn MY103H702 stepper motors <click link for datasheet.

I will do the other tests shortly.
Same motors I have.

I was wondering if the switches are actually adjusting the idle current when the motor is stationary and not the operating current, the data sheet isnt clear. If that was the case then the 100% setting corresponds to the RMS phase current set by the resistors which would be the RMS current shown by the ammeter

The maximum peak current this could be for these motors on 13.3v (allowing .5v for Vref) is:
Unipolar: 13.3/6.2 = 2A (which appears to be your bipolar series setting)
Bipolar Parallel 13.3/3.1 = 4A
Bipolar Series 13.3/12.4 = 1A (which appears to be your bipolar parallel setting)

Do you have a stand-alone ammeter or a 'scope?