Wheelock, Inc.

Bart Falzarano, Jr

Joseph Kosich

John J Nicol

A microprocessor provides a pulse width modulated pulse train at a predetermined frequency to a tuned resonant circuit having a transducer element. The first pulse has a predetermined width. The pulse widths of successive pulses are decreased in a predetermined manner until the pulse width reaches a minimally desired width. The next generated pulse has the first predetermined width and each successive width is decreased in the same predetermined manner. This pattern is generated repeatedly. Each one of these generated patterns produces an audible waveform from the tuned resonant circuit which changes over time. If the pulse train frequency, the pulse width modulation, and the circuit's resonant frequency are chosen correctly, the audible waveform will have the same characteristics as the waveform produced by a specified bell which has been struck.

Electronic bell tone generator

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.

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Bayville, NJ, United States of America

Bart Falzarano, Jr