I have a box full of small motors, DC and AC. Looks like they came out of printers, scanners, small appliances, toys -- you name it. Is there a way to divine the voltage/amp requirements just by looking at these darn things?Some have numbers stamped on the cases but most don't.

 

Briefly, NO.
If no definite markings then it is a case of identifying the motor technology, DC brushed, stepper, RC ECM etc and then trying a suitable power supply circuit.
Max.