Originally Posted by Chip-3Door
The danger of a signal going DC of course is that the motor then stops being a motor and starts being a heater, which is obviously potentially catastrophic if the current draw is allowed to be too high.
not at all Chip...
the motor is always going to be a heater - provided the power rating of the motor isn't exceeded it won't care if the supply is DC or PWM or whatever else. For example, as mentioned above, a 12V peak 100% duty cycle PWM drive signal
IS 12V DC
You just have to establish what DC voltage is required to drive it fully open and not exceed that.