I want to be able to detect when a stepper motor is not receiving any power from the driver (e.g. like the driver failed, the motor failed or there was a power loss); and I want to do this electronically. I have thought about using a current sense resistor on both phases connected to one side of a voltage comparator with the other side connected to a 6V reference (the motors are run at 12V). The comparator will run high when the voltage is enough, and low when is not. Additionally, I plan to use this signal to control a hobby servo (the one’s that are pwm controlled). It only has to have 2 states, fully open or fully closed.
Question to the analogue engineers; would this method work? If not what would?