A bit of surgery on an old inkjet printer on its way to be recycled, left me with two motors. A brushed DC one, and a bipolar stepper. A quick test with a 3V battery indicated that both motors work. Now the big question: with no marking (except the stepper is marked OKI), how to determine the appropriate operating voltage? Any smart tricks or tips out there? Increasing the voltage until something starts to smell funny is one approach, but I would prefer something slightly less destructive.