Yesterday, by using the ATX power supply (12V yellow plug), and after applying a heat sink and using a fan (aka blow dryer on cool setting) to the main chip on the motor driver, I was able to get the stepper motor to perform up to its full specifications. It worked fine at all speeds without stutter, including those in the midrange that were giving us trouble before. And the torque was more than enough to turn the same valve used by Matt Herpin several years ago in his own experiment.
I think this worked because we finally gave it a power supply with the right characteristics:
- a max current rating (18A) that was greater than the stepper motor’s rating (2A).
- a voltage that was many times higher (12V) than the stepper motor’s rating (3V), as recommended on the forums.
Anyway, some important notes:
- Matt says we can continue to use his valve if needed. It is attached to the stepper motor using the same metal connection he had milled for this purpose. It requires the small allen wrench to loosen.
- The quality of the stepping started to decline after 30-60min of continuous use. It could be that the voltage was running too high for too long, or something with the ATX power supply (I took a picture of the spec label).
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