Gte Automatic Electric Incorporated

Gte Automatic Electric Labs Inc.

Gte Business Communication Systems Inc.

Larry A Woodworth

Eduard F Boeckmann

Gary Grantland

Hugh S Montgomery

A protective circuit consisting of two diodes which functions along with other external circuit elements to provide protection against transients for an integrated circuit utilized to generate dial pulses in an electronic telephone circuit. By means of included diodes, excessive transients are prevented from entering the integrated circuit internal circuitry and disturbing the memory included therein or other operational characteristics.

Transient resistant key operated pulse generating calling device circuit

In a hold circuit including a silicon controlled rectifier (SCR) normally turned on and connecting the hold circuit to a subscriber line, a first hold release circuit outputs a trigger signal to a transistor turning off the transistor and disconnecting a line seizing network. A second hold release circuit outputs a trigger signal to a second transistor responsive to the line seizing network being disconnected. The second transistor connects a load resistor across the SCR dropping the holding current flowing through the SCR causing it to turn off. The second hold release circuit is also arranged to output its trigger signal to the second transistor responsive to a pre-arranged timing interval.

Electronic hold release circuit

In a hold circuit connectable to a subscriber telephone line, a silicon controlled rectifier is turned on by a user operated momentary pushbutton connecting the positive side of the line to the hold circuit. A comparator circuit sensing the initial value of the loop voltage, turns on a transistor and connects a line seizing network across the subscriber line.

Electronic hold circuit

An improved loudspeaking substation circuit employing a dual-tone multi-frequency signal generator wherein output tone levels are regulated by the substation transmission circuit when operating in either a loudspeaker or handset mode. The circuit further provides for preventing acoustic feedback and self-oscillation between the loudspeaker and handset transmitter while transferring between either mode.

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Huntsville, AL, United States of America

Larry A Woodworth