Stromberg-carlson Corporation

Patrick M Kelly

Stanley L Russell

Alton E Dorazio

An automatic call generator is connectable with the main distribution frame of a common control telephone system and monitors the operation of the system. To this end, the automatic call generator is connected to dedicated line and trunk circuit ports and attempts to place calls from one dedicated spot to another. If the system fails to terminate a call within a prescribed period of time, a malfunction is noted. Two malfunctions within a prescribed set of programs for monitoring the system cause a system alarm to be generated. The call generator also tests itself after proceeding through assigned programs for monitoring the system.

Automatic call generator

A digital interface especially useful for isolating a speedily responsive circuit from the effects of transients at its input such as may be caused, for example, by contact bounce in a relay. The circuit includes a monostable multivibrator connected to be set in response to changes of alternately opposite polarity of the input signal and having a characteristic period equal to a predetermined fraction of the normal minimum interval between intended changes of the input signal. The output of the multivibrator is used to drive a flip-flop at the end of the characteristic period to produce the desired output signal. Thus, the circuit is non-responsive to relatively rapid alternations of the input signal immediately following a change of its condition, yet responds reliably when the input signal changes state and remains stable in its new state for a time exceeding the characteristic period of the multivibrator.

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Victor, NY, United States of America

Patrick M Kelly