US552823A - Frank r - Google Patents

Description

(No Model.)

P. R. COLVIN. TELEPHONE SYSTEM.

Patented Jan. 7, 1896 AN DREW Ev GRAHAM FHOTMmm. WASH mmc N. M2.

UNITED STATES FFICB@ PATENT FRANK It. COLVIN, OF NEIV YORK, N. Y., ASSIGNOR TO THE INTERIOR TELEPHONE COMPANY, OF SAME PLACE.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 552,823, dated January 7, 1896. Application filed February 2, 1895. Serial No. 537,089. (No model To @ZZ wiz/m, it may concern:

Beit known that I, FRANK R. CoLvTN, a citizen of the United States, residing in the city, county, and State of New York, have invented certain new and useful Improvements in Telephone Systems, of which the following is a speciiication.

This invention relates to telephone systems, its object being to provide a simple and effective central-oiice apparatus for coupling subscribers circuits and permitting the central-office operator to hear and converse with both connected subscribers without disturbing the relations of their circuits.

N'Vith this end in view I provide in each connecting-cord used to couple the subscribers circuits an induction-coil, one winding of which is in series with the cord and the other winding of which is in a local circuit including a battery-transmitter, a battery and a telephone-receiver. 'With this provision the central operator may at all times hear and be heard by the subscribers without manipulating switches as has heretofore been customary.

The novelty' of' the invention will be more fully explained hereinafter and will be definitely indicated in the claims.

In the accompanying drawing is diagraminatically shown a system embodying my improvenients.

A B C represent three subscribers stations, the rst having a private line connecting it with central oihce, and the other two having a common line connecting them therewith.

The drawing illustrates a system equipped with metallic circuits, though the main featuresof the invention may be carried out with grounded circuits. At each station a magneto-bell l il lb is normally included in circuit, and switches 2 2, die., are provided for cutting it out and including a batterytransmitter 3 and receiver 4f. The switch is provided with a hook to support the telephone and is so arranged that when shifted to its talking position it will not support the telephone, thus insuring a proper restoration of the circuits when conversation is concluded. This construction is fully described and claimed in a patent granted to me March 27, 1894i, No. 517,263.

In a normally-olsen ground at each station is a key 5 5, &c., by which a battery (i at central station may be thrown into circuit through annunciators or indicators 7 7 in parallel relation to each other. A connectin g-cord or plurality of such cords is provided at central ohice bywvhich the several subscribers circuits may be interconnected. These cords, one pair of which is shown, terminate in switch-plugs S 9, comprising two metallic surfaces or cylinders insulated from one another and mounted on a common support. The inner cylinder is adapted` to engage a pin lO 10 of a jack-switch, and the outer one a springcontact ll 1la of said switch. Thus when the two plugs are inserted in theV switches corresponding to two subscribers circuits the subscribersA` instruments will be in circuit with one another. A battery l2 is inserted in that side of the cord which when the plug is in circuit will be disconnected from the annunciator. In series relation With the other side of each cord is one Winding of an induction-coil13, the other winding of which is in a local circuit la including a battery, carbon transmitter and receiver. The ratio of transformation of the induction-coil is preferably 1:1. Each central operator is also provided with a callingplug l5 connected or adapted to be connected with a magneto-call generator 1G and an answering-circuit including a battery, a transinitter and a receiver, as shown in circuit 17'.

Certain features of the system herein described are claimed in another application filed by me. The feature of novelty to which claim is made in the present application is the induction-coil 13 and its relation to the connectingcord and listening circuit by which the central-office operator is in' continuous communicating relation to both subscribers during transmission. As heretofore organized the listening-telephone is placed in parallel relation to the talking-circuit, requiring a branch of very high resistance to prevent a diversion of too much current and reduction of the loudness of transmission at the distant stations. Obviously, with my organization, the induction-coil being in series may be made of very low resistance and cannot divert any current from the distant inlOO vio

struinents. The quality or ioudness of trimsl ,mission is Vtherefore unafieetcd amd is the' saine for all instruments in circuit. i Molte-U over, the difference of resistance of two conznected circuits, :byvieasoncf diierenceof length or conductivityor 'different iocztl vatinospheific online conditions, cannot render vone instrument-feeble, as might be the cesse where the central-0fce iisteni11g-receiverisv in t branch circuit across the line.

Having vthus described my invention, what v I cla-iin as new, and desire to secure by Letters v Patent, is-

1. rihecombination with :t number of tele-v v phone lines extending to the cent1-ai station,

cfa cord connect-o1'foiiconnecting the cir cuits togetbeil for conversation, an induction coil having thesecondztry connected in series with v saidv cord vccnnectoi, and it telephone I transmitter and receiver in circuit With the piininryof stid induction coil, Iwhereby the telephone set may remain continuously in op'-v erative connection with the coi-d connectorsubstantially asvdescribed. y

i?. A telephone system comprising t plurality of subscribers circuits connecting with t v central office, battery transmitters at the sev eral subscribers stations, n eonnectingeord o1i cords stt central ofee, a battery for furnishingti-msnitting current :in circuit with' seid cord, and an induction vcoil having one winding; in series with the cord and the other Winding vinn local listening circuit inciudin transmitting and receiving' apparatus.

y In testimony whereof I have hereunto sul ,J

Images