Communications: electrical – Condition responsive indicating system – With particular system function
Patent
1983-04-11
1986-06-17
Rowland, James L.
Communications: electrical
Condition responsive indicating system
With particular system function
250384, 340516, 340529, 340629, G08B 2900, G08B 1710
Patent
active
045959145
ABSTRACT:
A self test circuit for a combustion products detector automatically periodically tests whether the sensitivity of the sensor is in a predetermined range between minimum and maximum sensitivities. Transistor switches selectively connect different test impedances across the sensor for respectively simulating two amounts of combustion products, one of which is slightly less than the amount corresponding to the maximum sensitivity level and the other of which is slightly greater than the amount corresponding to the minimum sensitivity level. If the sensor either produces a smoke output signal in response to the first test or fails to produce an output signal in response to the second test, then the smoke alarm is actuated after the tests are completed to produce a unique fault signal, the alarm annunciator being inhibited during the test.
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Myer Daniel
Pittway Corporation
Rowland James L.
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