Abstract: A device controller synchronizes a counter to the detection of sunrise or sunset by photoelectrically sensing daylight, thereby establishing an approximate time reference for scheduling the timing of device activations to occur at any time of day or night. An uncalibrated method of measuring sunlight yields more reliable scheduling, relative to sunrise and sunset events. The integral approximate time reference is kept synchronized, even if occasional faults in detection of sunrise or sunset occur. The rules employed to establish and maintain synchronization, and the dynamically variable rules for evaluating changes in light intensity, contribute to the reliable performance of the controller apparatus. Inherently self-adapting and automatic, a potentiometer for setting a time parameter input and a push-button for setting a time parameter input are combined in the apparatus in such a way to yield further utility without complicating the programmability.