The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 24, 1981
Filed:
Mar. 29, 1979
Henry W West, Red Bank, NJ (US);
Wheelock Signals, Inc., Long Branch, NJ (US);
Abstract
An automatic audible signaling system for use in emergency warning and direction of people in the evacuation of buildings and the like comprises control apparatus at a central station, a plurality of local amplifiers mounted at remote locations, and at least one loudspeaker connected to each amplifier. The control apparatus comprises an audio preamplifier and, coupled to the output thereof, a modulation transformer having a center-tapped secondary to which a DC voltage is applied when it is desired to operate the loudspeakers. This arrangement supplies mixed DC power and low-level audio signal voltage to each of the remote amplifiers and obviates both the use of a high-power amplifier at the central station and the transmission of a high-power audio signal from the central control apparatus to the remote loudspeakers. The system also comprises supervisory means including a differential amplifier that normally produces no output but that, in response to a malfunction of the system, operates a relay that gives a trouble indication. The local amplifiers are specially designed to respond to the mixed AC/DC signal and to facilitate line supervision.