I on the other hand, automatically presumed he has a feedback loop, because otherwise things are quite ugly from my perspective.
The feedback loop job is to cut off the current when it reaches limit, and then let it fall down to zero (or not). Assuming a coil resistance of 1 ohm, the 12v psu / 1ohm, without a current limit and in condition longterm (inductor dissapears from circuit), it would go to ohms law and get up to 12Amps per coil which means coils will probably melt. No wander the coils getting hot. Instead, a bit of wander of how the test psus survived.
So without a feedback loop it has to be a much lower voltage psu, like 1v psu for a coil of 1 ohm, if we target a current of 1A. And again in this case the rise times will be bad and i expect motor dynamics also poor. Probably in an application where the motor just needs to sit there and just hold its position most of the times, and move slowly otherwise. Realm of some high inductance and high coil resistance motor (12ohms per coil) for that, which is contrary to the normal stepper type used in reprap.
The feedback loop job is to cut off the current when it reaches limit, and then let it fall down to zero (or not). Assuming a coil resistance of 1 ohm, the 12v psu / 1ohm, without a current limit and in condition longterm (inductor dissapears from circuit), it would go to ohms law and get up to 12Amps per coil which means coils will probably melt. No wander the coils getting hot. Instead, a bit of wander of how the test psus survived.
So without a feedback loop it has to be a much lower voltage psu, like 1v psu for a coil of 1 ohm, if we target a current of 1A. And again in this case the rise times will be bad and i expect motor dynamics also poor. Probably in an application where the motor just needs to sit there and just hold its position most of the times, and move slowly otherwise. Realm of some high inductance and high coil resistance motor (12ohms per coil) for that, which is contrary to the normal stepper type used in reprap.