A power control module which can be used to automatically open a power circuit for electrically operated devices, particularly battery operated devices, during predetermined periods of non-use. A timer is reset by a motion detector indicating continuing use. The timer controls a transistor switch which closes and opens the power circuit as required. The timing interval can be user-selected e.g., by programming a microprocessor controller. The transition time between conductive and non-conductive states of the transistor can also be controlled to prolong the life of incandescent bulbs or other sensitive load devices.