12V stepup regulator

[TomWS]

Since you have both motors in hand, can you measure the respective winding resistances and see if they are truly different motors?

Looks like 80 ohms for the 12V and 28 for the 5V.

Thanks for taking the time to measure and report this!  I'm surprised that there is a difference.

Tom

[perky]

That's interesting, 80 ohms gives 150mA at 12V (1.8W), and 28 ohms gives 178mA at 5V (0.9W). If the power was the same we'd expect the resistance at 5V to be somewhat less. It's almost like it's exactly the same motor but with a additional resistors in series with the windings at 12V.
Mark.