Abstract: A combined smoke and gas detector utilizes a conventional smoke detector IC (44) which is operable to drive a piezo element (46) and an LED (94) to provide indication of a smoke or gas detection. An ionization chamber (58) is operable to detect smoke and a gas detector (98) is operable to detect gas. A comparator (104) detects the output of the gas detector (98) for input to the logic circuitry of the IC (44). The LED (94) is modulated to provide a distinction between gas detection and smoke detection in addition to the tone output from the piezo element (46).
Type:
Grant
Filed:
March 11, 1986
Date of Patent:
August 18, 1987
Assignee:
BDC Electronics
Inventors:
Robert H. Buck, Kent G. Cowan, John P. Doughty, Stephen E. Marshall