Communications: electrical – Systems – Call station
Patent
1975-03-21
1976-05-04
Habecker, Thomas B.
Communications: electrical
Systems
Call station
324 51, 340412, G08B 1900
Patent
active
039551830
ABSTRACT:
An alarm circuit includes an alarm condition indicating section having an alarm indicator, such as a lamp, and a power supply therefor, the lamp becoming illuminated in response to sensing of an alarm condition. Also included is an alarm condition sensing element, such as a normally open switch or a photoconductor normally incident with a low level of light, which under normal conditions, i.e., in the absence of an alarm condition, exhibits a very high impedance, but which in response to an alarm condition exhibits a low impedance. The alarm condition sensing element is connected to the alarm condition indicator and in response to the sensing of an alarm condition and being placed in its low impedance condition causes the alarm indicator to provide an alarm indication. A circuit is also provided for testing the operability of both the alarm indicator power supply and the continuity therefrom to the alarm sensing element, which test circuit accomplishes its test function without actually placing the alarm condition sensing element in an alarm condition or electrically simulating the circuit conditions which exist when such is done.
REFERENCES:
patent: 2664795 (1954-01-01), Tone
patent: 2944252 (1960-07-01), Muehter
patent: 3562730 (1971-02-01), Hill
Habecker Thomas B.
The Mosler Safe Company
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