Count discriminating fire detector

Details Count discriminating fire detector Count discriminating fire detector

1980-03-13

1981-04-07

Caldwell, Sr., John W.

Communications: electrical

Condition responsive indicating system

Specific condition

250381, 250574, 340629, G08B 1710

Patent

active

042609844

ABSTRACT:
A detecting circuit is responsive to the change in a physical parameter indicative of a fire such as smoke, heat, flame or the like, and a comparator circuit connected to the detecting circuit produces detection pulses in synchronism with an oscillator circuit when the change in the physical parameter exceeds a predetermined amount. A counter circuit counts the detection pulses and produces an output which triggers a switching circuit when a predetermined number of consecutive detection pulses are counted. When triggered, the switching circuit transmits an alarm signal to an alarm receiving panel. Connected between the counter circuit and the switching circuit is a monostable multivibrator having a time constant which is equal to or smaller than the supply voltage rise time constant of the counter circuit so as to prevent the trigger signal from being applied to the switching circuit during the transition period immediately following the connection of the power source. A detection sensitivity validation means directs the detection pulses from the comparator circuit to the outside so as to facilitate the sensitivity adjustment.

REFERENCES:
patent: 3842409 (1974-10-01), Mayer
patent: 3846772 (1974-11-01), Peberdy
patent: 3946241 (1976-03-01), Malinowski
patent: 4011458 (1977-03-01), Malinowski
patent: 4015121 (1977-03-01), Gagnon et al.
patent: 4151522 (1979-04-01), Yamauchi
patent: 4163969 (1979-08-01), Enemark
patent: 4185278 (1980-01-01), Linlelmann et al.
patent: 4186390 (1980-01-01), Enemark
patent: 4193069 (1980-03-01), Cooper et al.

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