US1474430A - Telephone bepeatee - Google Patents

Description

Nov. 20 1923.

O. B. BLACKWELL TELEPHONE REPEATER Filed May 29, 1919 INVENTOR. 7 (1B. Blackwell BY C A TTORNIJ Patented Nov. 20, 1923.

UNITED STATES PATENT OFFICE.

OTTO B. BLAGKWELL, 0F GARDEN CITY, NEW YORK, ASSIGNOR 'lO AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TELEPI-IUNE REPEATER.

Application filed may 29, 1319. Serial No. 300,558.

To all rv/1 0 m it may concern:

Be it lznown that l, Or'ro l3. BLAonwnLL, residing at titarden City, in the county of Nassau and State of New York, have invented certain Improvements in Telephone Repeaters, of which the following is a specilication.

This invention relates to telephone repeaters and more particularly to repeaters for phantomed transmission systems.

Tn systems of this character it is common practice to separate the phantom from the side circuit current at repeater installations by means of a pair of repeating coils or transformers, in each side circuit. The phantom current is led from the midpoints of these coils to the repeater of the phantom circuit, and the side circuit currents are con ducted to the side repeaters by connections to the secondary winding of the coils. The metallic continuity of the line conductors is thus interrupted at the repeating coils. so that telegraph current or other direct current for signaling purposes cannot be sent over the line, without the use of auxiliary apparatus for shunting the current around the repeater installation. Such apparatus must also be provided for alternating sig naling currents of low frequencies, because of the low efficiency of the transformers and other repeater apparatus when traversed by such currents.

The essence of the present invention is the elimination of the above described repeating coils and the preservation of the conductive continuity of the line conductors, so that the auxiliary apparatus for transmitting telegraph and other signaling currents may be dispensed with. This is accomplished by the use of a transformer having the coils of one winding inserted in th line conductors, and the coils of the other winding associated with one side, either input or output, of the amplifying device. The other side of the amplifying device is associated with the line conductors by means of a secon d transformer connected between the midpoints of inductance coils or like devices bridged across the side circuits. The coils of the first transformer are so connected that it responds to phantom current but not to side current and the second transformer receives only phantom current by virtue of its balanced connections to the line. Side current is thus excluded from the amplifyng device.

; The inductance devices which s rve to associate one of the above transformers with. the phantom circuit may serve also to associate the side repeaters with the side circuits.

A good understanding of the invention may be had by considering the following detailed description, with reference to the accompanying drawing which, in diagrammatic form, shows an arrangement of circuits and apparatus embodying this invenlion.

In this drawing reference characters 1, 2, 3 and 4: designate the line conductors of a four-wire phantom group. The conductors l. and 2 are traversed in opposite directions by current of one side circuit and the conductors 3 and ll, by current of the other side circuit. Phantom current flows in one dire. tion through conductors l and 2 in parallel, and in the other direction, through conductors 3 and 4:, in parallel.

A transformer 15 is shunted across each side circuit at points 50 and 51 on the line conductors, and the midpoints 52 and 53 of these transformers are connected to the terminals of a transformer 21. A bridge is thus established across the phantom circuit, and phantom current flows through this bridge from one side of the phantom circuit to the other. This current traverses half of the winding of each transformer 15 in opposite directions but flows through both halves of transformer 21 in the same direction. It has therefore no magnetizing effect on transformers 15, but it does create a flux in transformer 21, so that this transformer impresses the phantom current on the amplifying device 40. This device may be of any suitable type and preferably comprises an electron tube, the grid, filament and plate circuits of which may be connected in the usual manner. The outgut circuit of this amplifying device is associated with the primary winding of a transformer 20, comprising coils 33 and 34 connected in series. The secondary winding of this transformer is comprised of coils 25 to 32, a pair of these coils being inserted in each line conductor. The coils of each winding are symmetrical and arranged, preferably on a common core as indicated by the dashed lines, in such manner that coils 25, 26, 29 and 30 are magnetically additive with respect to coils 27, 28, 31 and 82. When, therefore, the amplified phantom current enters the primary winding of transformer 20, the secondary thereof causes flow of current in one direction in wires 1 and 2 and in the opposite direction in wires 3 and 4. The above described apparatus constitutes a repeater for the phantom circuit, which repeater derives phantom current from the line by trans, former 21, amplifies this current by means of the device 40 and impresses the amplified current on the line by means of transformer 20. None of the current from transformer 20 enters transformer 21 under conditions of proper balance of the phantom circuit be cause the points 50 and 51 in both. pair of Wires are of like potential relative to the electromotive forces impressed on the wires by the symmetrical coils of transformer 20. Transformer 21, in other words, is conj to transforn'ier 20. Although the amplifying device 40 is described in the present embodiment of the invention as h ring its input circuit associated with the shunt trans former 2'1 and its output circuit with the series transformer 20, there is no objection from a theoretical standpoint to an arrangement associating the input side of device 40 with the series transformer 20 and the outputside, with the shunt transformer 21.

In case it is desired to provide repeaters also for the side circuits, transformers 15 may serve as the input "ansformer of the side repeaters. The drawing shows a singleelement two-way repeater of well known type for each side circuit, each repeater comprising an amplifying device l0 whose input circuit is associated with transformer 15 and whose output circuit is connected to the coils 10 and 11 of the primary winding of the output transformer 5. The secondary winding of this transformer comprises coils 6 to 9 inclusive, inserted into the line wires, one on each side of points 50 and 51. The connection of coils 6 and 7 is such that they are magnetically additive to coils 8 and 9 when traversed by side circuit current so that this transformer impresses side current on the line, when its primary receives current from the device 40.

Each of the side circuit repeaters operates by shunting part of the side current through its transformer 15, amplifying this current in device l0 and returning the same, amplilied, to the line conductors by transformer 5. Transformers 5 and 15 are conjugate under proper conditions balance so that current from one does not enter the other.

it should be noted that there is no interference between the phantom and side circuit apparatus. The phantom transformers are unresponsive to side current, and the side current transformers to phantom current, provided always, that proper balance is maintained. rrlt-hough transformers are used in the present embodiment of the invention to provide the side circuit neutral points 52 and 53, it is readily understood that any other suitable devices may be used for this purpose, as for example, inductance coils.

The line conductors are metallically con tinuous through the repeater circuits and therefore transmit direct current or low frequency alternating current, such as is commonly used for signaling. Condensers u; and 17 are inserted into the primary windings of transformers 15 to prevent these windings from short circuiting the signaling currents. Th invention thus provides for normally continuous signaling paths through the repeater installation. To make the arrangement particularly adapted for composited systems, retardation coils l8 are bridged across the input transformer 15 and 21. The condensers and retardation coils constitute filters, which provent the low frequency ringing current, and the pulsating telegraph current from entering the repeaters and thus causing interference in the telephone circuits. It is readily understood that each telegraph or other signaling circuit may be formed of one line conductor and ground or may be constituted of two line conductors, as usual in the art.

Although only one form of apparatus and circuits embodying the invention is shown and described herein, it is readi y understood that various modifications and changes may be made therein within the scope of the following claims, without departing frmn the spirit and scope of this invention.

What is claimed is:

1. ln combination, a plurality of electrical conductors, conductively continuous side circuits each formed of a portion of said conductors and adapted for the transmission of direct current, a phantom circuit forn'ied of said conductors, a repeater intermediate the ends of said conductors, said repeater having input and output sides and means for operatively associating both sides of said repeater with said conductors in their phantom circuit relation.

2. In combination, a plurality of electrical conductors, circuits over said conductors normally continuous to direct current, a phantom circuit over said conductors, a repeater intermediate the ends of said conductors, said repeater having input and output sides and means associated with said conductors for operatively associating both sides of said repeater with the phantom circuit.

In combination, a plurality of continuous conductors arranged to form a phantom circuit, a translating}; device intermediate the ends of said conductors, means for associating one side of said device with said circuit in shunt relationship and means for associating the other side of said device with said circuit in series relationship. I

4. In combination, a plurality of electrical conductors arranged to form side and phantom circuits, a repeater, and means for operatively associating said repeater with said phantom circuit, said means comprising a transformer having the convolutions of one winding in the side circuit conductors.

5. In combination, a plurality of electrical conductors arranged to form side and phantom circuits, a translating device having one side associated with said phantom circuit in shunt relationship and a transformer for associating the other side of the device with said circuit in series relationship the convolutions of one side of said transformer being inserted into the side circuit conductors.

6.111 combination, a plurality of electrical conductors arranged to form side and phantom circuits, a translating device, coils in said side circuit conductors for associating one side of said device with said phantom circuit in series relationship, and electrical connections to points on said conductors intermediate said coils bridging the other side of said device across said phantom circuit.

7. In combination, a plurality of electrical conductors arranged to form side and phantom circuits, a translating device, coils in said side circuit conductors for associating one side of said device with said phantom circuit, and means having conjugate relation to said coils for associating the other side of said device with said circuit.

8. in combination, a plurality of conductively continuous line conductors arranged to form a phantom circuit, a repeater for said circuit and comprising input and output circuits, a device bridged across said conductors for associating one of said repeater circuits with said phantom circuit, a transformer conjugate to said device and comprising a winding connected in series with said conductors for associating the other repeater circuit with the phantom circuit.

9. In combination, a phantom group comprising two pairs of line conductors arranged to form a phantom circuit, a repeater for the phantom circuit, a transformer for associating one side of said repeater with said circuit in series relation ship, said transformer comprising two coils in each line conductor all of said coils being magnetically additive, when traversed by phantom circuit current and a second transformer having one winding connected to each conductor intermediate the coils therein for associating the other side of the repeater in shunt with said line, and in conjugate relationship to said first transformer.

10. The combination with a plurality of electrical conductors arranged to form two side circuits and a phantom circuit, of a repeater in each side circuit, comprising a circuit bridged across the corresponding side circuit, a repeater for said phantom circuit comprising an amplifier and input and output circuits therefor, means for bridging one of said last-mentioned circuits across said circuits of said side circuit repeaters, and means for associating the other of said circuits with said phantom circuit in series relationship thereto.

11. In combination, a plurality of line conductors arranged to form a phantom and two side circuits, a repeater for each circuit, each repeater comprising an input and an output circuit, means for each side repeater for bridging one of its circuits across the corresponding side circuit, means for the phantom repeater for bridging one of its circuits across the first mentioned means, and means traversed by both phantom and side circuit currents and selectively responsive thereto, for associating the other circuit of each repeater with the line conductors.

12. In combination, a phantom group comprising four conductors arranged to form a phantom and two side circuits, a. transformer for each side circuit comprising a pair of coils in series with each conductor of the side circuit, the coils in one conductor of each side circuit being magnetically opposed to the coils in the other conductor with respect to phantom current but additive with respect to side circuit current, a second transformer for each side circuit conjugate to said first transformer and having one winding connected across the corresponding side circuit conductors at points therein intermediate said pairs of coils, an amplifying device for each side circuit and operatively associated with the shunt and series transformer thereof, a third transformer having a pair of coils in each side circuit conductor, the coils in each side circuit being magnetically opposed relative to side circuit current and additive relative to phantom currents, a fourth transformer bridged across the midpoints of the first transformer and having conjugate relationship to said third transformer, and an amplifying device operatively associated with said third and fourth transformers.

13. A transmission system comprising a plurality of circuits, one of said circuits being a phantom, a line conductor traversed at each point by current in said phantom and another of said circuits, and a repeater for said phantom circuit associated with said conductor intermediate its ends.

-. 14. In a composite transmission. system, a plurality of continuous line conductors, a plurality of circuits including a phantom circuit Over said conductors, a signaling. circuit associated with one of the conductors comprised inv said phantom circuit each point of said conductor beingtrayersed. by current in said phantoinand said signaling circuits, a repeater for said: phantomucircuit, and means for preventingthe signaling current from causing interference in said plurality of circuits.

15.In combination, a plurality-of .line conductors a phantom circuit comprising said conductors, a repeater, and meansiinterposed in said line....conductors between the terminals thereof for operativelyassociating said repeater with said phantom circuit, said means being connected. to the conductorszsqzasism-permit the flow oi di rect current therethrough.

16. In combination, a phantom group of conductors "comprising side and phantom circuits, a transformer having tl1ec 0nv0 lutions ofone Winding in-series in said conductors and traversed "by current in both :side and phantom; (circuits, a translating device, and qafsecond winding for said transformer having its terminals associated with said translating deviceand having its 'convolutions s0 related to those ofithevother Winding that said translating device is operatively associated only with said phantom circuit.

In testimonyqvhereof, I have signed my name to, this specificationthis 23rd day of l/Iay, $1919.

OTTO B. BLACKVVELL.

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