Title: Three wire detection circuit

Abstract: A three wire circuit for supplying electrical power to active, power-consuming detection devices and communicating electrical signals providing supervisory information and fire alarm information to a control panel. Two wires supply electrical power the third carrying supervisory and alarm signals. Passive non-power-consuming detectors may also be utilized on said circuit. Detection devices switch the positive power to the signal wire in the event of an alarm and an end-of-line device switches the negative power to the signal wire through a current limiting device as a supervisory signal when conditions are normal. The end-of-line device measures the voltage on the power supply wires and opens its switch when the voltage falls below a specific level to indicate trouble. The circuit can carry an alarm signal in spite of and overriding a supervisory signal.

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Inventors: DeLime, III, Thomas L. (Parsipanny-Troy Hills, NJ, US)

Application Number: 576511
Filing Date: 1975-05-12
Publication_date: 1976-08-31
Assignee: Firetek Corporation (Clifton, NJ)
Primary Class(es): 340/517 324/522, 340/533, 340/577
Other Classes:
US Patent Ref:

3603949	Sep, 1971	Walthard	340/409.
3676877	Jul, 1972	Kobayashi	340/176.

Other Refs:
Primary Examiner: Caldwell, John W.
Assistant Examiner: Wannisky, William M.
Attorney: Cannon, Jr.; James J., Cannon; James J.