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US 4,071,709 AGranted
Line conditioning and transfer circuit
AssigneeGTE Automatic Electric Laboratories Incorporated
InventorsDavid Quon Lee, Richard Michael Rovnyak
Life of this patent
Estimating the term…
Abstract
A circuit for electrically preconditioning a telephone line and switching an associated ringing generator on and off at the instant of opportune circuit conditions to eliminate circuit transients. The line circuit is switched by means of a relay so that an equipotential charge exists on either side of the switching contacts at closure and with zero current through the contacts at opening to eliminate suppression devices.
Claims7
A telephone system including, a telephone line connected to at least one subscriber station including a ringer;
- a central switching system including a central processor unit, line supervisory means, and line relay means connected to said central processor unit normally connecting said line to said line supervisory means, and a ringing signal generator connectable to a power source;
- the improvement comprising:
- voltage sensing means connected between said ringing signal generator and said power source;
- and a control circuit including circuit connections to said line relay, to said voltage sensing means and to said central processor unit, initially operated in response to said central processor unit to connect said power source to said ringing signal generator through said voltage sensing means and to operate said line relay, whereby ringing current from said ringing signal generator is connected to said telephone line to operate said subscriber station ringer.
1 more element
Dependencies are inferred from the claim text.