A lighting system, which includes one or more lighting apparatus sets, includes a control circuit. The control circuit has an ambient light sensing component and processing circuitry which produce a control signal whenever the intensity of ambient light reaches a given level and remains at that level...http://www.google.es/patents/US4645980?utm_source=gb-gplus-sharePatente US4645980 - Lighting system having photosensing timing switch circuit
Lighting system having photosensing timing switch circuit
