Smoke alarm

Details Smoke alarm Smoke alarm

1975-06-23

1977-05-03

Caldwell, John W.

Communications: electrical

Systems

Call station

250574, 356207, 340251, G08B 1710

Patent

active

040217922

ABSTRACT:
A smoke alarm having a smoke chamber with at least two inlet ports together with an array of louvered apertures and flue means to provide free access to the smoke chamber for smoke flowing in any direction within a hemispherical zone. A circuit employing photocells to measure smoke obscuration and reflection by means of an improved wheatstone bridge to sound a loud audible alarm. A relaxation oscillator coupled to a light source which is used for the optical portion of the smoke alarm. The oscillator produces an alarm to indicate failure of the light source, which alarm is distinguishable from the smoke alarm. A heat sink thermally coupled to the light source to induce filament vapors to condense on non-critical portions of the light source.

REFERENCES:
patent: 2537028 (1951-01-01), Cahusac et al.
patent: 3505529 (1970-04-01), Moore
patent: 3576558 (1971-04-01), Devries
patent: 3585621 (1971-06-01), DiCello
patent: 3774186 (1973-11-01), Enemark
patent: 3868184 (1975-02-01), Marsocci

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