Occupancy sensor

These savings accrue because in a spaces with access to daylight the occupant may decide on their return that they no longer require supplemental electric light.

The prototype utilized existing ultrasonic intrusion alarm technology coupled to conventional industrial timers, with basic switching elements.

First prototype was crafted on a plywood base; the first model required a separate transmitter and receiver processing 20,200 cycles per second of sound energy.

Mr. Fraser was employed by and developed the device for the Embarcadero Center high-rise office complex in San Francisco, and as such employee did not profit from the invention.

He took the concept to Unisec security devices and had them build a single piece transceiver based on 277VAC - the level of electricity used for commercial lighting in the Embarcadero Center complex.

Noted local columnist Herb Cain made mention that one should not sit too long in the stalls at Embarcadero Center, and the word caught on regarding the technology.