Smoke detector with remote alarm indication
First Claim
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1. Apparatus for indicating an environmental alarm condition comprising:
- two input terminals receiving direct current electrical power from a remote source supplying current in a normal and an alternative polarity,an environmental sensor producing an alarm signal in response to an alarm condition, andan alarm responsive to the alarm signal to indicate the alarm condition in a first mode of indication;
characterized by means for sensing the polarity of current at the power input terminals including a generator of a secondary signal distinguished from the alarm signal when current at the input terminals is in the alternative polarity; and
means coupling the sensing means and secondary slgnal to the alarm to cause the alarm to operate in a second mode of indication.
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Abstract
A smoke detector receiving at two input terminals DC power from a remote source not only gives an alarm indication in response to a significant density of smoke, but senses the polarity of DC power at the terminals and generates a secondary signal, distinguishable from the alarm signal, when the polarity of power source is reversed.
26 Citations
9 Claims
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1. Apparatus for indicating an environmental alarm condition comprising:
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two input terminals receiving direct current electrical power from a remote source supplying current in a normal and an alternative polarity, an environmental sensor producing an alarm signal in response to an alarm condition, and an alarm responsive to the alarm signal to indicate the alarm condition in a first mode of indication; characterized by means for sensing the polarity of current at the power input terminals including a generator of a secondary signal distinguished from the alarm signal when current at the input terminals is in the alternative polarity; and means coupling the sensing means and secondary slgnal to the alarm to cause the alarm to operate in a second mode of indication. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification