US584415A - Charles e - Google Patents

Description

(No Model.)

O. E. SCRIBNER. TELEPHONE LINE CIRCUIT.

No. 584,415. Patented June 15, 1897..

lJNiTnn STATES PATENT Curios.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE YVESTERN ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-LINE CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 584,415, dated June 15, 1897.

Application filed August 1,1895. Serial No. 557,827. (No model.)

.To all whom it may concern: I have shown a form of my invention in the Be it known that I, CHARLES E. SORIBNER, attached drawing. a citizen of the United States, residing at Chi- At a substation A are located a transmitcago, in the county of Cook and State of Illiting-telephone b, a receiving-telephone b, a

nois, have invented a certain new and useful signal-bell b and a generator b of signaling- Improvement in Telephone-Line Circuits, current of the usual type. Line conductors (Case No. 396,) of which the following is a full, 1 and 2 extend from these appliances to a cenclear, concise, and exact description, refertral station C, where they are connected with ence being had to the accompanying drawing, the usual apparatus in a telephone-switch- 10 forming a part of this specification. I board.

My invention concerns the substation ap- At the substation the transmitting-teleparatus of metallic-circuittelephone-lines, its phone I) and the receiving-telephone b are purpose being to so arrange the telephonic included serially in a conductor uniting the and signaling appliances at the substation as two line-wires l and 2. The receiving-tele- I 5 to dispense with all switches without impairphone here represented has usually a resisting the efiiciency of operation of either of the ance of about twentyfive ohms and the instruments. transmitting-telephone a normal resistance My invention is particularly useful in conof one hundred or two hundred ohms. The nection with telephone systems in which curbell b is connected in a ground branch from 20 rent for exciting the transmitting-telephone conductor 1. This bell may havea resistance is supplied over the line-circuit during the of one thousand ohms or more and should be use of the telephone, although it is not limcharacterized by high impedance. The genited to such use. erator b is in a similar ground branch from My invention consists in including the sigconductor 2 of the line-circuit. It also should 2 5 nal-bell, of high resistance and impedance, in have high resistance and impedance. a ground branch from one of the line conduc- At the central station line conductor 2 is tors and the generator of signaling-current, led to ground through an annunciator cl. also of high impedance, in a similar branch Conductor 1 is here shown grounded through from the other line conductor and in placing an impedance-coil 6, but so far as my inven- 30 the telephonic appliances in a permanentlytion is concerned it may be left open. Both closed bridge or cross wire of the line-circuit. line-wires are provided with normally open At the central station the line-annunciator is terminal contacts in a spring-jack f in the located in that line conductor which includes switchboard. V the subscribers generator, while the outgoing The switchboard is furnished with a pair 3 5 signals from the central station are transmitof connecting-plugs g and g, which are united 8 5 ted over that line conductor which is more through the helices of an induction-coil 7L directly connected with the bell at the subthat is, the tips of the connecting-plugs are station. connected together through a conductor 3,

When the substation-generator is operated, which includes the helices h h of the induc- 40 very little of its current finds circuit through tion-coil, while the sleeves of the plugs form 9:)

the telephone and the call-bell to earth on theterminals of a conductor 4, including heliaccount of the high resistance of this path. ces [71 721 The point of union of helices h 77. On the other hand, only a small fraction of and that of helices 7L3 7L4 are connected tosignaling-current sent from the central stagether through a battery '2', which is designed 45 tion traverses the subscribers generator. to supply current to-the substation-telephone 5 Then the telephone is in use, no appreciable during the use of the latter. The strength portion of the telephonic current in the line of this battery may be so adjusted with relais shunted through the signaling apparatus tion to the annunciator d as not to operate it, on account of the high impedance of these inorany well-known device may be employedto 5o struments. prevent the excitement of the annunciator 10o during the connection of the battery with the circuit-as, for example, the inclusion of a condenser in the ground branch with the annunciator. If desired,- any suitable form of clearing-out annunciator may be employed.

Keys is are included in conductor 4-, the switch-lever of either key being adapted, when it is depressed, to open the circuit of this conductor and to connect the tip of the corresponding plug with one pole of asource Z of signaling-current.

The subscriber at stat-ion A, by turning his generator 19 may transmit a signaling-current to operate the annunciator d. As before stated, only a small portion of the generated current will traverse the telephone and callbell. When, replying to the signal thus transmitted, the operator inserts the plug g into spring-jackf, the circuit of battery 1' is closed through the transmitting and receiving telephones at the substation, thus supplying current for exciting the transmitter. Fluctuations in the current in the line-circuit produced by the transmitter are reproduced in the circuit with which plug g may be connected, through the medium of the inductioncoil h, in a well-known manner.

The escape of telephonic current through the ground branches at the substation is prevented by the impedance of the instruments in those branches. At the same time any deleterious influence on the balance of the line which their presence might tend to exercise is prevented by their symmetrical connection with the circuit. The impedance of the two instruments b and 72 being substantially the same, the electrostatic balance of the line will not be appreciably disturbed by their permanent connection with it.

If the operator should desire to signal to subscriber at station A, she would insert the plug g into the spring-jack f and would then depress the key 70. The current from the signaling-generator Z would then find circuit over conductor 1 and through the bell b at the substation.

I claim as new The combination with a metallic-circuit telephone-line, of a transmitting-telephone and a receiving-telephone in a bridge thereof at a substation,a signal-bell in a permanentlyclosed branch from one line conductor, a magneto-generatorin a branch from the other line conductor, an annunciator at the central station connected with the line to receive current from the generator, means for applying signaling-current to the line also at the central station to operate the signal-bell, a source of current adapted for exciting the transmitting-telephone at the central station and means for connecting the said source of current with the line;.Whereby switches at the substation are avoided, as described.

In witness whereof I hereunto subscribe my name this 13th day of June, A. I). 1895.

CHARLES E. SCRIBNER.

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