Abnormal condition responsive means with periodic high sensitivi

Details Abnormal condition responsive means with periodic high sensitivi Abnormal condition responsive means with periodic high sensitivi

1978-07-31

1980-09-09

Caldwell, Sr., John W.

Communications: electrical

Condition responsive indicating system

Specific condition

250381, G08B 1710

Patent

active

042220467

ABSTRACT:
An ionizing type smoke detector device has an output voltage which is compared with a reference voltage and upon the output dropping below the reference, a horn is energized. The reference voltage is normally quite low to reduce the number of false alarms and thus the smoke detector is relatively insensitive to smoldering fires which may require a high sensitivity of the smoke detector device. A timer means periodically modifies the reference voltage to a high value for a short period of time to make the smoke detector more responsive to smoldering fires and yet with the higher sensitivity for the short period of time the number of false alarms are kept at a minimum. Additionally a counter circuit is provided for counting the outputs of the smoke detector over three timing periods and if an output exists for three consecutive periods, an output to the horn is provided.

REFERENCES:
patent: 3295121 (1966-12-01), Meyer
patent: 3407299 (1968-10-01), Jehle
patent: 3657737 (1972-04-01), Hamm et al.
patent: 3725660 (1973-04-01), Doherty
patent: 3728703 (1973-04-01), Burnett
patent: 3849685 (1974-11-01), Larsen
patent: 3872449 (1975-03-01), Scheidweiler

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