Akzona Incorporated

Protel, Inc.

Gerald J Yachabach

Regis B Mellon

Gary L Eisenhauer

Housing for a key pad, carrier select and credit card bezel for coin

Key pad and credit card bezel for coin telephones

A circuit for protecting telephone lines from AC hazardous voltages. The circuit includes an amplitude discriminator triggered at a predetermined voltage level connected to the telephone lines, and providing an output pulse for each zero voltage crossover of the hazardous voltage. A digital pulse counter counts a predetermined number of output pulses from the amplitude discriminator, which in turn operates a switch after the predetermined number of pulses are counted, opening the telephone lines between the central office and the telephone instrument until the hazardous voltage has been removed from the lines.

Hazardous voltage protection circuit

There is provided a line circuit for connection to a key telephone system for indicating an incoming call, a call placed on hold, and an answered call. There is further provided a means for automatically indicating that the incoming call has been placed on hold for a predetermined time period. There is further provided a solid state device which switches telephone instrument lamp current for visual indication of the various line circuit operations.

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Lakeland, FL, United States of America

Gerald J Yachabach