INTERFACE FOR A SUPERVISED MULTI-INPUT AUDIBLE WARNING SYSTEM

摘要

An interface for a supervised multiple input, audible warning system is disclosed. The interface continuously monitors or supervises a plurality of circuits between a control unit and an alarm unit for electrical faults. Each circuit represents a separate alarming condition. All the circuits are coupled to but normally isolated from each other and a common circuit for driving a piezoelectric device. The isolation is accomplished by means of a semiconductor switch normally reverse biased. The semiconductor switch prevents the supervising current of one circuit from driving the piezo by isolating all possible flow paths to all circuits without current flow in the alarming direction. Upon sensing an alarming condition, the direction of the current in the alarming circuit reverses resulting in forward biasing the semiconductor switch. The current in the alarming circuit, no longer isolated from the common circuit, actuates the common circuitry necessary for generating the audible warning . The interface circuits may be connected to an addressable micro controller for selecting a multitude of sounds.