Abstract: An automatic door closer providing for use as a light duty door opener and having a slip clutch for protecting the electric gear drive power unit from damage due to overspeeding on excess loads applied by overriding manual door operation. Zener diodes across the power supply to the electric drive motor effectively throw a heavy electrical load on the motor and cause the clutch to slip if the motor is sufficiently oversped and caused to act as a higher voltage bucking generator, as by manually forcing the door substantially faster in the direction in which it is being driven. A direct current motor is used at considerably lower than its rated voltage so that electrical power may be safely applied continuously for holding the door closed with the motor stalled, and without the clutch slipping, with the clutch set to slip only when the force applied thereto is significantly higher than the force required to stall the motor yet safe for the drive unit.