US749306A - Telephone system - Google Patents

Description

, No. 749,306. 'PATENTED JAN. 12, 1904.

\ A. D. T. LIBBY.

TELEPHONE SYSTEM.

APPLICATION FILED DEU. 3, 1902.

N0 MODEL.

i the talking-circuits.

lines, 'as well as in the ordinary type, to main- `ing of the wanted subscribers.

UNITED STATES Patented January 12, 1904.

PATENT OFFICE.

l ALBION D. T. LIBBY,V OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SVVITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 749,306, dated January 12, 1904. Application filed December 3, 1902. Serial No. 133,673. (No model.)

4cut-off relays of` the lines are bridged across the same or otherwise connected with the talking-circuits, and are therefore actuated over It 1s necessary 1n these tain the cut-off relays actuated during the call- The callingkeys are arranged to open the connection of the central battery with the lines at the time of ringing to prevent the ringing-current from going back over the lines of the calling subscribers, and thus proving an annoyance to them by causing noise in their telephones. The cutting' off of the battery, however, unlessiauxiliary means are provided, denergizes'the cut-off Vrelays and prevents the de- One such means is to employ an auxiliary generator or generators which is normally disconnected `from the lines and cord-clrcuits, but which during ringing is temporarily connected therewith, and is arranged to hold up the said relays. This is objectionable for several reasons, among which `maybe mentioned the eXtra expense involved in the cost and running of the eXtra generators, the additional space required for the installation,` and a greater compl'ication throughout.

`My invention is designed to accomplish the desired result with much less complication than heretofore and with greater economy and efficiency.

The invention is illustrated in the accompanying drawing, in which the figure represents adiagram of two subscribers lines and the central-oiiice apparatus involved in establish-` ing connections for conversation.

Two line-clrcuits L and L are shown eX- office C. At the substation the sleeve line4 conductor 3 terminates in a hook-switch 4, which is normally grounded through a signalingbell 5. A receiver 6 and transmitter 7 are adapted to be connected in series between the line conductors when the receiver is removed from the hook-switch 4, at which time also the grounded bell is disconnected from the conductor 3. This apparatus at the substation is intended merely to typify any of the usual common battery transmission sets, as it is evident that any other suitable arrangement may be employed in so far as the features of my invention are concerned.

At the central oiiice the line conductors 2 and?) terminate, respectively, in springs 8 and 9 of a cut-olf relay R, the normal Contact of spring 8 being connected by conductor 10 with the winding of the line-relay R2, which is joined through the medium of conductor 11 with the live pole of the charging-battery B and the other pole of which is grounded. The

,normal contact of spring 9 of the cut-off relay is grounded, as indicated by the conductor 12. The line-relay R2 controls the local circuit of the line-signal S, which in this instance is in the form of a small incandescent lamp. Each line is also provided with an answering-jack .I and with a suitable number of multiple jacks J2 and J3, the tip and sleeve contacts of which are respectively connected by means of conductors 13 and 14 With the forward contacts of the springs 8 and 9 of the cut-off relay R. The winding of this relay is bridged between the said conductors 13 and 14, as shown.

The opcrators outfit comprises a plurality of cord-circuits,` one only-being shown, and which is provided with an answering-plug I and a calling-plug P2, each having tip and sleeve contacts adapted to register with the like contacts of the spring-j acks or connectionterminals of the lines, and the tip-contacts ofn which are connected together through the lnedium of the tip-strands t and t2 and theinterposed condenser c, while the sleeve-contacts are joined by the strands s and s2 and the interposed condenser c2. From the tip and sleeve strand of the answering-plug conductors 15 and 16 extend to the opposite poles of the battery B, as shown, and each includes one of the differential windings of the supervisory relay o1, which-is adapted to control through its normally open contacts the local circuit of the supervisory lamp S2, associated with the answering-plug P. The strands t2 and s2 of the calling-plug P2 are likewise connected by means of conductors 17 and 18 with the opposite poles of a second charging-battery B2, and, as before,these conductors include the differential windings of the supervisory relay r2, which controls through its normally open contacts the local circuit of the supervisory lamp S2, energized also from the battery B2.

The operators receiver 19, the secondary of her-induction-coil 20, and a condenser c3 are adapted to be bridged between the two strands t2 and s2 by means of the listening-springs 21 of a suitable listening and ringing key. Her transmitter 22 and the primary of her induction-coil 20 are shown in a local circuit with a small battery B3; but it will be apparent that any other suitable source of current may be employed. An alternating-current ringing-generator 23 is employed to call the wanted subscriber and is connected between the ground and the sleeve-spring 24 of the ringing and listening key. A suitable non-induc tive resistance, which may be a lamp 25, is included in the ringing-circuit. The outer contact of the tip-spring24 of the ringingkey is connected by c0nductor26 with the battery-lead 112, extending to the ,live pole of the battery B2, and said conductor includes a suitable vretardation-coil 27. The line L2 is provided with apparatus similar to that of the line L and which is designated by the corresponding reference characters.

rlhe operation is as follows: The subscriber A desiring a connection with the subscriber D takes up hisreceiver and closes the line conductors 2 and 3 togetherA at the substation, thereby completing the path for c urrent from the battery B over the conductor 11 through the line-relay R2, conductor 10, and thence over the tip line conductor 2 and through the substation instruments and back to the cen'- tral oflice over a sleeve line conductor 3 and thence through the grounded branch 12. The line-relay responds to this current and closes the local circuit of the signal-lamp S, which is lighted to indicate the subscribers call, upon seeing which the operator inserts the answering-plug P of her cord-circuit in the answering-j ack J of the line. The insertion of this plug closes a path for current from the battery B over both strands and s of the cord-circuit and the switchboard-conductors 13 and|14 ofthe line and through the cut-olf relay R. This relay therefore operates to disconnect the vline-relay R2 to render the line-signal S inoperative and to also connect the switchboard-section of the line with the external line-circuit, thus placing the line in condition for conversation. rlphe current now flows from the battery B through the supervisory relay 7 and over the metallic line to the substation as well as through the cut-0H relay R, with the result that the magnetic eects through the coils of the relay fr are neutralized and the relay does not attract its armature and the local circuit of the supervisory lamp S2 is not closed. Upon learning the connection desired by the calling subscriber the line is tested by means of the tip of the calling-plug P2. If the line is busy, a cord-circuit similar to the one shown and connected with the same batteries is inserted in one of the jacks of the line, so that all of the test-rings thereof and which are connected with the sleeve sides of the line are thereby connected With the live pole of the battery B or B2. Upon touching the tip of the plug P2 to one of the test-rings, therefore, a complete path for current is providedffrom the test-terminals over the tip-strand t2 of the testing cord-circuit and through conductor 17 to ground. This varies the charge of poten- 'tial upon the operators condenser to such an extent as to cause a surge of current through her bridge and produces a click in her receiver. If the line is idle, however, the testrings are entirely insulated, s0 that no path for current is completed when the line is tested and no click is received. Upon finding the line in this condition the plug P2 is inserted and the ringing-key 24 operated. rlhe operation of this ringing-key connects the alternating-current generator 23 between the sleeve-spring and ground, and the tip-spring is connected with the conductor 26, leading to the live pole of the battery B2 through the retardation-coil 27. At the same time the springs 24 open the strands of the cord-circuit through their normal contacts to prevent the passage of the ringing-current back over the cord-circuit and through the instrument of the waiting calling subscriber. The severance of this circuit, however, does not deenergize the cut-off relay R of the line L2 for the reason that steady current for maintaining the same operated is furnished from the live pole of the battery B2 over the conductors 11u and 26 and thence through the switchboard-cable 13, the winding of the cut-off relay R, switchboard-cable 14, and thence over the sleeve-spring 24 of the ringing-key and through the ringing-generator 23 to ground. The current iowing over this path is suiiicient to maintain the cut-0E relay R operated during ringing, and at the same time the ringing-current from the generator 23 is not shortcircuited through this path by reason of the presence therein of the retardation-coil 27, which serves to effectually prevent its passage IOO ITO

and to confine it toits intended path over the sleeve line conductor 3 of the. line L2 and through the grounded signaling-bell 5 at the substation. After calling the subscriber and t 5 before his response a'path for current is pro `vided from the battery B2 over the conductor 18 andtlirough one winding of the supervisory relay r2 and thence over the sleeve-strand of the cord-circuit, the sleeve-conductors 14 and 3 of the line L2, andthrough the bell 5 of the i substation to ground. This serves to unbalance the magnetic effects in the two coils of y relay r2 and energizes the same to cause it to S3 associated with the plug P2, which is lighted to indicate the fact to the operator that the called subscriber has not yet responded. Upon the response of the Icalled subscriber the i ground through the bell 5 `at the substation is -20 removed, and the metallic circuit is completed for current from the battery B2, with 'the attending result that the relay 1'? is rendered neutral, and the local circuit of the supervisory lamp S3 is4 opened toy extinguish the same. The subscribers are now in conversation, and the batteries B and `B2 are furnishing current to the respective substations with which they t are Aassociated for transmission purposes. The windings of the supervisory-relays r and r2 are preferably placed upon the opposite ends oftheir cores or otherwise separated, so that although the magnetic elfects produced by the steady current flowing therethrough t during conversation areneutralized the magt .netic effects dueto rapidly-varying voice-currents are not neutralized, but cause'suiiicient impedance topi-event thevoice-currents from `being"slfiort-circuited through the bridges of the cord-circuitin which they, together with the batteries, arelocated.; i t t Although, the `electrical dimensions of the severaldevic'es lemployed are not of the essence of my invention and may be varied considerably, good, results have beenobtained with an impedance-coi] 27 of two hundred and ninety ohms Aandthe other parts of the usual or desired dimensions. .It will be understood t that any Ysuitable ringing and listening key y may be provided, but preferably one in which the `movement of `a single lever serves to si- Althoughbut one type of line-circuit has been described, I do, notdesire to so confine the invention, but hold it tov include all the uses and applications to which it; maybe found capable andrparticularly apply to those line-circuits in which the cut-01T relays are energized by current flowing over `a portion of thetalking-circuit.` t i y Itclaim---iA t i V- i 1. In a `telephone system, the combination witha telephone-line, of a line-signaling device therefor, a cut-off relay for the line adapted when actuated to render said line-signaling z device inoperative a cord-circuit to estabclose' the local circuit of the supervisory lamp i multaneously operate the opposite springs.,`

lish connections with the line, a steady current source associated with said cord-circuit and adapted during a connection to furnish current over a portion of the talking-circuit for the operation of said cut-0H relay, a ringing-generator adapted to be connected with the line to call the subscriber located thereon, means to open the cord-circuit during calling to prevent the ringing-current from iowing back over the same, an auxiliary path for current completed from said source through said cut-off relay during calling, and means in said auxiliary path to permit the passage of steady current and to prevent the passage of the ringing-current, substantially as described.

2. In a telephone system, the combination with a telephone-line, of a line-signaling device therefor, a cut-off relay for the line adapted when actuated to render said line-signaling device inoperative, a cord-circuit to establish connections with the line, a steady current source associated with said cord-circuit and adapted during a connection to furnish current over a portion of the talking-circuit for the operation of said cut-.off relay, a ringinggenerator-adapted to `be connected with the line to call the subscriber located thereon, means to open the cord-circuit during calling to prevent the ringing-current from flowing back over the saine, an auxiliary Apath for current completed from `said source through said cut-ofi? .relay during calling,and a retardation-coil in said auxiliary-path toprevent the passage of ringing-current andyto permit the passage of steady current, substantially as described. i

, 3. In a telephone system, the combination with atelephone-line, ofza line-signaling device therefor, a cut-ofi' relay for the line adapted when actuated to render said line-signaling -device inoperative, a cord-circuit to establish connections with the line, a steady current source connected therewith and adapted4 to furnish current over a portion of the talkingcircuit during a connection for the operation of said cut-off relay, a ringing-generator adapted to be connected with theline to call the subscriber located thereon, means-to open the normal connection with said source during calling, an auxiliary path for current completed from said source through. said cut-off relay during calling, and a retardation-coilin said auxiliary path, substantially as described.

4. In a telephone system, the combination witha telephone-line, of a line-signal therefor,

`a cut-.off relay bridged between the line conductors and adapted when actuated to'render the line-signal inoperative, a `cord-circuit to establish connections with the line, `a source of steady current bridged. across the cord-circuit andadapted during a connection :to furnish current over the talking-circuit for the operation of said cut-off relay, a ringing-generator adapted to be connected with the cordcircuit to call the wanted subscriber, the cordcircuit being opened between said source and the cut-off relay at the time of calling the subscriber, an auxiliary path for current from 'the line-signal inoperative, a cord-circuit to 'establish connections with the line, a source of steady current bridged across the cord-cir- A cuit and 'adapted during a connection to furnish current over the talking-circuit for the operation ofs-aid cut-off relay, a ringing-generator, a key located in the cord-circuit between thel bridge containing said source and the calling-plug, said key being arranged to sever the cord-circuit when the ringing-generator is connected with the calling-plug, an

auxiliary path for current from said source completed by said key during calling through said 'cut-OH? relay to maintain the same operated, and a retardation-coil in said auxiliary path tovprevent the passage thereover of the ringing-cu-rrent, substantially as described.

6.` In a telephone system, the combination Withfa telephone-line, of a connection-terminal normally disconnected therefrom, a relay -for connecting said connection-terminal with the line, a central source of current adapted to Vbe connected in the metallic circuit for talking purposes', means for operating said relay from said source when connection is made with the line by current flowing over a path including a portion of the talking-circuit, means for sending a ealling-currentover the line of the called subscriber only andl at the same time maintaining said relay in operated condition from said' source, and means for preventing thel shortfcircuiting of the ringing current through said source, substantially as described;-

H7. The combination withatelephone-line, of a'connection-terminal normally disconnected therefrom, -a relay for connecting said connection-terminal with the line,a charging source ofv electricity,`a calling source of electricity, saidcharg'ing source'being adapted to energiZe-said relay when-connection is made with the line, a ringing-key'for connecting said calling` source with the line ofa called subscriber and for disconnecting the normal path for current from said charging source, an auxilia'ry vpath for current from said charging i i i Y Y source completed by the ringing-key during calling, and a retardation-coil in said auxiliary path, substantially as described.

8. =In a-telephonesystem, the combination with a telephone-line', of a line-signal therefor, a cut-olf relay bridged between `the line conductors and adapted when actuated to render the line-signal inoperative, a cord-circuit to establish connections with the line, a source of steady current connected withthe cord-circuit and adapted during a connection to furnish current over thetalking-circuit for the operation of said cut-off relay and for conversational purposes, a ringing-generator adapted to be connected with one side of the cord-circuit to call the wanted subscriber, an auxiliary path for current from said source adapted to be connected with the other side of the cordcircuit during calling, the cord-circuit itself being at this time severed, a retardation-coil in said auxiliary path to prevent the passage thereover of the ringing-current and to conne it to the called line entirely, substantially as described. f Y

9. In a telephone system, the combination with a telephone-line, of a line-signal'operated by current from the central oice when the subscriber is calling, a magnet to render said signalinoperative when a connection is established with the line for conversation, a central source of current adapted to be connected in the line for talking, said magnet being operated. from said source during a connection by current over a portion of the talking-circuit, a calling-generator for sending ringingcurrent over the line of thel called subscriber only, means for simultaneously sending continuous current through said magnet to maintain the same actuated during calling, and a retardation-coil in the path of the latter current to prevent the passage thereover of the ringing-current, substantially as described.

10. The combination with a telephone-line, of a charging source of continuous current to furnish current for talking, Va line-signal, a magnet adapted to be energized from said source to render the said signal inoperative, the magnet-circuit including a portion of the talking-circuit, a calling-generator, means to connect said generator with the line' and to open the circuit of said source through said magnet, means for temporarily sending'continuous current through said magnet during ringing to maintain the same actuated, Vandal retardation-coil included lin the path of said temporaryv current to prevent the passage thereover of the ringing-current,substantially as described. i L

ll. The combination with a telephone-line, ofa charging source of continuous current to furnish current over the line for talking, a line-signal, a magnet adapted to be energized IOO from said source during a connection to render said 'signal inoperative, a cord-circuit to establish connections with the line for talking, a calling-generator, means to connect said generator with the line and to open `the cordcircuit, means for temporarily sending continuous current through said magnet during ringingv to maintain the'same operated, and a retardation-coilA included in the path of said temporary current to prevent the passage thereover of the ringing-current, substantially as described.

12. The combination with a telephone-line, of a charging source of continuous current, a magnet adapted to be energized by said charging source when connection is made with the line, a calling-generator, aringing-key adapted to connect said calling-generator with the line and to open circuit through said magnet, means controlled by the ringing-key for tcmporarily sending a continuous current through i said magnet during the'time the calling-generator is connected with the line, and a retardation-coil in the path of said temporary current to prevent the passage thereover ofthe ringing-current, substantially as described.

13. rlhe combination with atelephone-line, of a relay associated therewith, a cord connector for uniting said line with another telephone-line, a charging source of continuous current adapted to be connected with said line to send current through said relay, a calling-generator adapted to produce a noncontinuous current, a ringing-key adapted to connect said calling-generator with the line and to open the circuit of said charging source through said relay, means for temporarily sending a continuous current through said relay to energize the same during the timeI the calling-generator is in circuit, and a retardation-coil included in the path of said latter current to prevent the passage thereerator with the line and to open the circuit ofsaid charging source through said relay and means for temporarily sending a continuous current through said relay during the time the calling-generator is connected in circuit, and a retardation-coil included in the path of said temporary continuous current, substantially as described.

15. The combination with a telephone-line, of a relay in a bridge between the two limbs of said line, a charging source of electricity adapted when4 connection is made with the line to energize said relay, a calling-generator, a ringing-key adapted to connect said callinggenerator with the line and to open the circuit of said charging source through said reand a retardation-coil included in the path of lay, means to temporarily `send continuous current through said bridgedrelay during ringing by the actuation of said ringing-key,

said latter temporary current to prevent the passage of ringing-current, substantially as described.

16. The combination with a telephone-line,

of a relay associated therewith, a cord connector for uniting said line with another telephone-line, a charging source of continuous current adapted to be connected with said cord connector through said relay and furnishing current for talking purposes, a calling-generator adapted to produce a non-continuous current, a ringing-key adapted to connect said calling-generator with the line and to open the circuit of said charging source through said relay, means for temporarily sending a continuous current through said relay to energize the same during the time the calling-generator is in circuit, and a retardation-coil included in the path of said latter temporary current to prevent the passage of the ringing-current, substantially as described.

17. The combination with a telephone-line, of a line-signal therefor, a magnet to render said line-signal inoperative during a connection, a source of current connected with the line during a connection to energize said magnet over a path including a portion of the talking-circuit and to furnish current for talking purposes, a calling-generator, a ringing-key adapted to connect said calling-generator with the line and to open the circuit of said charging source through said magnet, means actuated by` said ringing-key for temporarily sending a continuous current through said magnet during the time the calling-generator is connected with the line, and a retardation-coil included in the path of said latter temporary current, substantially as described.

1,8. The combination with a telephone-line,

of a line-signal therefor, a cut-off relay for the 4said relay to energize the same during the time the calling-generator is in circuit, and a retardation-coil in the path of said temporary current to prevent the passage of the ringingcurrent, substantially as described.

19. The combination with a telephone-line, of a connection-terminal normally disconnected therefrom, a line-signal, a relay for connecting said connection-terminal with the line and for simultaneously rendering said signal inoperative, a charging source of continuous current adapted to energize said relay and to furnish current for talking during a connection, a calling-generator adapted to produce a non-continuous current, a ringing-key to connect said calling-generator with the line and to IOO IIO

open the circuit of said charging source through said relay, means for temporarily sending a continuous current through said relay during the time the calling-generator is connected in circuit, a retardation-coil included in the path of the'latter temporary current for the purpose of preventing the passage over said path of the ringing-current, substantially as described.

20. In a telephone system, the combination with a telephone-line, of a line-signaling device therefor', a cut-off relay for the line adapted when actuated to render said line-signaling device inoperative, a cord-circuit to establish connection with the line, a steady current source associated with said cord-circuit and adapted during a connection to furnish current over a portion of the talking-circuit for the operation of said relay and over the line for talking, a ringing-generator adapted to be connected with the line to call a subscriber located thereon, means to open the cord-circuit during calling to prevent the ringing-current from flowing' back over the same, means for temporarily sending a continuous current through said cut-off relay during calling, and means connected in the path of said temporary current to permit the passage of the continuous current and to prevent the passage of the ringing-current, substantially as described.

21. In a telephone system, the combination with a telephone-line, of a line-signaling device therefor, a cut-Ol relay for the line adapted when actuated to render said line-signaling device inoperative, a cord-circuit to establish connections with the line, a steady current source associated with said cord-circuit and adapted during a connection to furnish current over a portion of the talking-circuit for the operation of said cut-off relay and over the line for talking, a ringing-generator adapted to be connected with the line to call the subscriber located thereon, means to open the cord-circuit during calling to prevent the ringing-current from flowing back over the same, means for temporarily sending a continuous current through said relay during calling, and a retardatione'coil in the path of said latter current to prevent the passage of ringing-current and to permit the passage of steady current, substantially as described.

22. In a telephone system, the combination with atelephone-line, of a line-signal therefor, a cut-off relay bridged between the line conductors and adapted when actuated to render the line-signal inoperative, a cord-circuit to establish connections with the line, a source of steady current bridged across the cord-circuit and adapted during the connection to furnish current for the operation of the cut-o relay, a ringing-generator adapted to be connected with the cord-circuit to call the wanted subscriber, the cord-circuit being opened between said source and the cut-off relay at the time of calling the subscriber, means for temporarily sending a continuous current through said cut-off relay during calling to maintain the same operated, and a retardationcoil in the path of said temporary current to prevent the passage thereover of the ringingcurrent, substantially as described.

4 23. In a telephone system, the combination with a telephone-line, of a connection-terminal normally disconnected therefrom, a relay for connecting said terminal with the line, a central source of current adapted to be connected in the metallic circuit for talking purposes, means for operating said relay from said source when connection is made with the line by current flowing over a path including a portion of the talking-circuit, a calling-generator for sending ringingcurrent over the line of the called subscriber only, means for simultaneousl y sending continuous current through said relay to maintain the same actuated during calling, and a retardation-coil in the path of the latter current to prevent the passage thereover of the ringing-current, substantially as described.

24. In a telephone system, the combination with a telephone-line, of a magnet connected with the talking-circuit thereof, a cord-circuit, a calling-generator, a ringing-key to connect said generator with the cord-circuit to call the subscriber upon the line, said key serving to open the cord-circuit during ringing, and a source of steady current and a retardation-coil in series therewith temporarily connected with the cord-circuit by said key in calling to maintain said magnet operated, the said retardation-coil serving to oppose the passage of the ringing-current, substantially as described. v

25. In a telephone system, the combination with a telephone-line, of a line-signal, a relay to render said signal inoperative when a connection exists, a cord-circuit, a source of current associated therewith and connected with the line during a connection to furnish current for talking and for the operation of said relay, the relay-circuit including one talking-strand of the cord-circuit and a portion of one side of the line with suitable return, a ringing-generator, a key to open the said relay-circuit when operated and to connect the said generator in the circuit of the line, means also actuated by said key for temporarily sending a continuous current through said relay during ringing, and a retardation-coil in the said temporary path so formed by the ringing-key, substantially as described.

26. In a telephone system, the combination with a telephone-line, of a line-signaling device therefor, a cut-off magnet for the line adapted when actuated to render said line-signaling device inoperative, a cord-circuit to establish connections with the line, a steady-current source associated with said cord-circuit and adapted during a connection to furnish current over a portion of the talking-circuit for the opera- IOO IIO

I SO

said generator with the cord-circuit and line to call the Wanted subscriber, said switch serving to open the cord-circuit during callingto prevent the ringing-current from ilowing back over the same and disturbing the calling subscriber, an auxiliary path for current completed by said key-switch from said source through said cut-off magnet during calling, `and a retardation-coil in said auxiliary path a to prevent the passage ofthe ringing-current, `substantially as described. 27. In a telephone system, the combination With a multiple-switchboard common-battery telephone-line having its switchboard-section normally disconnected from the external linetween the strands of the cord-circuit and adapted to send current through said relay to `actuate the same during a connection and to erator, a ringing-key in the cord-circuit bei tween the connection of the said battery there- With and the connecting-plug, said key serving when actuated to open the cord-circuit strands and thus disconnect said battery, said key serving at the same time to connect said generator between ground and one side of the telephone-line, to actuate the subscribers bell, an auxiliary path for current completed from the live pole of said battery to the other side of the line by said key during ringing Whereby current from said battery flows over said auxiliary path through said bridgedcut-oif i relay and the grounded ringing-generator to maintain the same actuated during ringing, and a retardation-coil included in said auxiliary path to prevent the passage of the ringing-current thereover and coniine it to the subscribers line, substantially as described.

28. In a telephonesystem, the combination with a telephone-line, of a line-signal therefor, a magnet torender said signal inoperative during a connection, a ringing-generator and a source of steady current connected with the line When calling the Wanted subscriber,` the current from said steady-current source serving to maintain said magnet operated during ringing and having its path completed through said ringing-generator, substantially as described.

29. In a telephone-system, the combination witha telephone-line, of a line-signal therefor, a magnet to render said signal inoperative during a connection', a ringing-generator, and a source of steady current connected with the line when calling the Wanted subscriber, the

current from said steady-current source serving to maintain said magnet operated during ringing and having its path completed through said ringing-generator, and means to prevent the ringing-generator current from being confined to the path of the steady-current source, substantially as described.

30. In a telephone system, the combination With a telephone-line, of a line-signal therefor, a magnet to render said signal inoperative during a connection, a ringing-generator, and a source of steady current connected With the line when calling the wanted subscriber, the current from said steady-current source serving to maintain said magnet operated during ringing and having its path completed through said ringing-generator, and a retardation-coil in said steady-current path out of the desired path of the ringing-current to prevent the latter from flowing thereover, substantially as described.

31. The combination with a telephone-line, of a signal therefor, a magnet to render said signal inoperative during a connection, a battery and a ringing-generator 'connected with said line When calling the subscriber, the battery and ringing-generator having derived circuits, the said generator being in the com- Irion portion thereof and the s aid battery serving to maintain said magnet operated during ringing, substantially as described.

32. In a telephone signaling system, amainline circuit, a non-continuous-current generator for ringing the substation, a continuouscurrent generator, means for connecting both to the main-line circuit simultaneously and by the same operation to call the Wanted subscriber, a line-signal, an electromagnet connected With said circuit to render said signal inoperative during a connection, said magnet being energized by said continuous-current generator during ringing and over a path of loW actual resistance but relatively high apparent resistance, substantially as described.

33. In an electric signaling system, a main circuit, anon-continuous-current generator for calling the substation, a continuous-current generator, means for connecting both to the said circuit simultaneously and by the same operation when it is desired to call the subscriber, a line-signal, an electromagnet in a IOO IIO

branch of said circuit and adapted to be enering a main circuit, a line-signal connected therewith, an electromagnet connected with the line to render said signal inoperative, an alternating-current generator for sending outgoing signals, a continuous or uniform-direction current generator and a retardation-coil, and a signal-sending key or circuit controller interposed between the main circuit and both generators and adapted when operated to close the circuit of both over the said circuit simultaneously.

35. In a telephone signaling system, a main circuit, a ringing-current generator and a continuous-current generator associated together at the central station of the said circuit, a circuit-closer for connecting both to the said main circuit simultaneously and by the same operation, means for disconnecting both at the end of the call without taking down the connection, a polarized electromagnetic bell at the substation responsive to alternating current only andv adapted to give a signal upon the operation of said circuit-closer, a line-signal, an electromagnet to render said signal inoperative during a connection and actuated by current from said continuous-current generator, and means to prevent the passage of ringing-current over said lcontinuous-current path, substantially as described.

36. The combination with a main circuit, of a line-signal therefor, and an electromagnet to render said signal inoperative during connection and` connected with the main circuit, a source of alternating current for sending outgoing ringing-currents over the circuit, a source of continuous current for actuating said electromagnet to render the said signal inoperative during ringing and having impedance in its path to prevent the passage of the ringing-current, and means for connecting both sources with the circuit simultaneously in the normal act of calling the wanted subscriber, substantially as described.

37. The combination with a main circuit, of a polarized electromagnetic call device included therein responsive to alternating currents, an alternating-current generator, a continuous-current generator and retardation-coil associated therewith, a signal at the same station as the said generators, an electromagnet connected with the said circuit to render said signal inoperative during a connection, and a compound circuit-closing device controlling the terminals'of both generators and their connections with the main circuit so that when operated in calling a subscriber to make such connections the said magnet will be operated by the continuous current to prevent the operation of said signal by the alternating current and the latter current will be confined to the desired path, substantially as described.

38. In an electric signaling system, the combination with a main circuit, a line-signal, a cut-off relay connected with talking-circuit and adapted to render said signal inoperative during a connection, an alternating-current generator, a relatively low resistance continuous-current generator to operate said relay during ringing, a circuit-closer controlling branch terminals of the said main circuit and also the terminals of both generators and adapted when operated to connect both with said main circuit, an electromagnetic resistance or retardation coil of low actual but high inductive resistance included in the circuit of the continuous generator to prevent the currents of the alternating generator from being short-circuited or shunted through the said continuous-current generator while offering little opposition to the continuous currents developed thereby.

Signed by me at Chicago, county of Cook, State of Illinois, this 28th day of November, 1902.

ALBION D. T. LIBBY.

Witnesses:

C. S. WINsToN, ROBERT LEWIS AMES.

Images