Power Saver

[bkamalnivas]

I want to build a circuit that would turn off the lights and fans if there is NO ONE in the room...
what are the basic ideas that i could employ to detect the presence or absence of a person in the room

 

[Externet]

Occupation detectors of several kinds are available at the electrical store, they work on several infrared, active, passive, zonal principles. Get one, dismantle it, reverse engineer to a schematic and put it together again. You will have all the right parts on hand for an unbeatable price.

 

[Willbe]

I'd say use motion OR'ed with sound [filtered for traffic noise] detection.