Balanced tone application system

Claim 2

A balanced tone application system for applying dial tones, busy tones, or the like generated by a tone generator, to telephone transmission line pairs in a balanced manner and for use in a telephone exchange of the type having a supervisory relay coupled across each transmission line pair, said system comprising: a transformer having a primary coupled to the tone generator and a secondary including first and second windings; a power source coupled to said first winding; a source of common potential coupled to said second winding; and switching means coupled to said first winding, said second winding, said power source, said source of common potential, and to a supervisory relay, and said switching means being capable of assuming first and second states for connecting the supervisory relay only to said power source and to said source of common potential when in said first state to thereby apply only energizing power to the supervisory relay and to the transmission line pair associated with the supervisory relay, and for connecting the supervisory relay to said power source, to said source of common potential, and to said first and second windings when in said second state to thereby apply both energizing power and the tone generated by the tone generator through said first and second windings to the supervisory relay and to the transmission line pair associated with the supervisory relay, whereby the supervisory relay isolates its associated transmission line pair from all other transmission line pairs.

Claim 3

A system in accordance with claim 1 wherein said switching means comprises a relay having first and second pairs of contacts, said first pair of contacts including a first make contact and a first break contact, and said second pair of contacts including a second make contact and a second break contact, each of said make and break contacts having first and second sides, said first sides of said first make and break contacts being coupled together and to one side of the supervisory relay, said first sides of said second make and break contacts being coupled together and to the other side of the supervisory relay, said second side of said first break contact being coupled to said power source, said second side of said second break contact being coupled to said source of common potential, said second side of said first make contact being coupled to said first winding and said second side of said second make contact being coupled to said second winding.

Claim 4

A system in accordance with claim 2 wherein said first and second windings include first and second ends, said first end of said first winding being coupled to said second side of said first make contact, said second end of said first winding being coupled to said power source, said first end of said second winding being coupled to said source of common potential, and said second end of said second winding being coupled to said second side of said second make contacts.

Claim 5

A system in accordance with claim 3 wherein said source of common potential is ground.

Claim 6

A system in accordance with claim 3 wherein said first and second windings comprise an equal number of oppositely wound turns to thereby provide the transmission pair lines with tones of equal and opposite polarity energy.

Claim 7

A system in accordance with claim 3 wherein said relay includes means for closing said make contacts prior to the opening of said break contacts.

Claim 8

A balanced tone application system for applying dial tones, busy tones, or the like generated by a tone generator, in a balanced manner to telephone transmission line pairs and for use in a telephone exchange of the type having a supervisory relay, wherein one transmission line pair is coupled across the supervisory relay, said system comprising: a relay having first and second pairs of contacts, said first pair of contacts including a first make contact and a first break contact, and said second pair of contacts including a second make contact and a second break contact, each of said make and break contacts having first and second sides, said first sides of said first make and break contacts being coupled together and to one side of the supervisory relay and said first sides of said second make and break contacts being coupled together and to the other side of the supervisory relay; a power source coupled to said second side of said first break contact; a common potential coupled to said second side of said second break contact; and a transformer having a primary and a secondary, said secondary comprising first and second windings, one side of said first winding being coupled to said second side of said first make contact and the other side of said first winding being coupled to said power source, one side of said second winding being coupled to said second side of said second make contact and the other side of said second winding being coupled to said common potential, and said primary being coupled to the tone generator; whereby, when a tone is not applied to the transmission line pair, said make contacts are open and said break contacts are closed to thereby connect said power source and said common potential across the supervisory relay to provide the supervisory relay and the one transmission line pair with energizing power, and when a tone is applied to the one transmission line pair, said make contacts are closed and said break contacts are open to thereby provide energizing power to the supervisory relay from said power source and said common potential through said first and second windings and to provide the tone generated by the tone generator to the one transmission line pair through said transformer and the supervisory relay, whereby the supervisory relay isolates the one transmission line pair from all other transmission line pairs.

Claim 9

A balanced tone application system for applying dial tones, busy tones, or the like generated by a tone generator, in a balanced manner to telephone transmission line pairs and for use in a telephone exchange of the type having a supervisory relay, wherein one transmission line pair is coupled across the supervisory relay, said system comprising: a relay having first and second pairs of contacts, said first pair of contacts including a first make contact and a first break contact, and said second pair of contacts including a second make contact and a second break contact, each of said make and break contacts having first and second sides, said first sides of said first make and break contacts being coupled together and to one side of the supervisory relay and said first sides of said second make and break contacts being coupled together and to the other side of the supervisory relay; a power source coupled to said second side of said first break contact; a common potential coupled to said second side of said second break contact; and a transformer having a primary and a secondary, said secondary comprising first and second windings, one side of said first winding being coupled to said second side of said first make contact and the other side of said first winding being coupled to said power source, one side of said second winding being coupled to said second side of said second make contact and the other side of said second winding being coupled to said common potential, and said primary being coupled to the tone generator; whereby, when a tone is not applied to the transmission line pair, said make contacts are open and said break contacts are closed to thereby connect said power source and said common potential across the supervisory relay to provide the supervisory relay and the one transmission line pair with energizing power, and when a tone is applied to the one transmission line pair, said make contacts are closed and said break contacts are open to thereby provide energizing power to the supervisory relay from said power source and said common potential through said first and second windings and to provide the tone generated by the tone generator to the one transmission line pair through said transformer and the supervisory relay, whereby the supervisory relay isolates the one transmission line pair from all other transmission line pairs.