Abstract: A selected predetermined coded alarm is provided indicative of the one of a plurality of leads on which a signal indicative of an alarm condition may appear. If a station coded alarm should be initiated during the transmission of a coded alarm, the coded alarm is immediately terminated and the station coded alarm is given priority and transmitted immediately. Upon completion of the station coded alarm, the coded alarm being transmitted at the time of the receipt of the station coded alarm is transmitted with the new transmission starting at the start of its code irrespective of the status of the transmission at the time of the interruption. Appropriate delays are provided between codes and code elements. The plurality of leads are sequentially scanned, but once a transmitted code is transmitted, it is not retransmitted on a subsequent scan unless a reset signal has been provided. Each transmitted code is repeated a predetermined number of times.

Abstract: A flexible, expandable alarm control system in which varying combinations of functional circuit blocks or modules can be selected and connected in positions on a control panel by the customer or user of the system. Thus, the system can be modified to satisfy changing functional requirements by substitution of modules; furthermore, it can be expanded by adding functional modules to a given control panel or by extending the system to auxiliary control cabinets in which more circuitry can be mounted.

Abstract: Apparatus and technique for supervising a public address system such that any faults on the lines connected to speakers in the system or any faults within the speaker structures can be detected and suitable corrective action can be taken. To accomplish this purpose, only three wires or lines need be taken or extended to each zone within the public address system.

Abstract: An electrical load is energized from an energy source that may not have the capacity to carry the load directly. More specifically, a capacitor is charged at a low charge current for a relatively long period of time and when the load is to be energized, the capacitor is discharged through the load in a relatively short period of time. Current limiting devices protect the power source. The charge and discharge intervals are initiated in response to polarity reversals of the power source. When the power source presents one polarity, the capacitor is charged; and in response to a polarity reversal, the capacitor is discharged through the load. A plurality of capacitors and associated load circuits may be connected to a single power source without feedback between the circuits. A current limiting device may be used to limit the initial load current. Typically, the load may comprise a plurality of lamps, horns, bells or buzzers to indicate an alarm condition.