an actuator comprising a motor for rotating a shaft connected via a gear train to an output device ; an interrupter vane connected to the output device and adapted to travel in a path corresponding to the movement of the output device ; and at least two interrupter switches , such as opto - interrupter switches , spaced apart from one another along the path of the interrupter vane at locations corresponding to travel limits of the output device . a controller energizes the motor in response to a command signal and de - energizes the motor in response to an indication from one of the interrupter switches that the output device is at or approaching one of the travel limits . the actuator may be a rotary or linear actuator , and may be particularly well - suited for avionics applications .