Circuit for time-controlled power supply

摘要

The mains supply (1) is coupled to the primary side of a transformer (2) that supplies a number of lamps (4,5,6). The secondary side of the transformer is coupled by a relay (10) coupled to a microprocessor based unit (12). The relay switches to allow power to be connected across the lamps when a daylight detector (1) is operated a a set level. When the time reaches a predetermined time a brief interrupt in the relay actuation is initiated. Restart is controlled by a lamp based microprocessor unit (18) that is programmed to monitor the time from the predetermined time onwards. When a specific time has elapsed or lights are turned off at the same time. The system ensures switch off at a constant time, irrespective of when the daylight switch is triggered.