Smoke detector

Details Smoke detector Smoke detector

1979-10-22

1981-02-10

Caldwell, Sr., John W.

Communications: electrical

Condition responsive indicating system

Specific condition

250381, 340629, 340630, G08B 1710

Patent

active

042505003

ABSTRACT:
In a smoke detector of the type wherein an alarm signal is generated to activate an audible indicator and an oscillator circuit drives a pulsating visual indication of standby readiness, the oscillation frequency increases between its standby and alarm modes. In addition, duty cycle means controls the operative period of the alarm indicator during each cycle of the increased frequency. The smoke detector includes a relaxation oscillator where the oscillation frequency is proportional to the charge rate of a capacitor. Independent current sources are connected through separate switches to change the charge rate of the capacitor and thus the oscillation frequency. Each switch is controlled by signals from a separate detector of a condition which requires that the oscillation frequency be changed, for example, the presence of smoke.

REFERENCES:
patent: 3462752 (1969-08-01), Stroh
patent: 3537087 (1970-10-01), Osborne
patent: 3798625 (1974-03-01), McMillian et al.
patent: 3842409 (1974-10-01), Mayer
patent: 3866195 (1975-02-01), Ried, Jr.
patent: 3872449 (1975-03-01), Scheidweiler
patent: 3946241 (1976-03-01), Malinowsi
patent: 4001723 (1977-01-01), Sheng et al.
patent: 4063227 (1977-12-01), Peterson

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