US1575271A - Telephone system - Google Patents

Description

March 2 1926. 1,575,271 y H. W. O'NEILL TELEPHONE SYSTEM Filed Dc. 1. 19%2 2 sheets-sheet 1 /Hveho'n' Hen/y 14./ @Ne/7l March 2 1926.

H. wjwoNElLL TELEPHNE SYSTEM Filed Dec. 1, 1922 Sheets-Sheet Patented Mar. 2, 1926.

il? il@ HENRY Wl ONJEILL. @El BBQGHLYllL. NEW" "YQ'RK, ASSfGNRiI-Ei XEZESTERN. ELEGTPSEC COMPANY, ENCQ'RQGEABTED, OIE' MEXX? YORK, Ni. Y., GQEEOEATION? OF NEVI YGRET.

iinnnrlnionn SYSTEM.

Application iled De'ceniber 1, 1922'. 'Serial No. 604,19.

fo @ZZ idiom may concern:

Be it l-nioivn that l, HENRY YV. OpNiirLi.,

a citizen ot the `United States, residing,I at

Brooklyn, in the county ot Kings, State ot Nev. York, have invented certain new and useful improvements in Telephone Systems, ot which; the tollowing` is a full, clear, con ciao, and exact description.

This invention relates to' telephone systeins and more particularly to signaling arrangements employed therein. Y

it is an object ot this invention to antoinatical-ly select signaling currents of dit'- iforent frequencies as reqnired for conti-'olling signals over different circuits.

lt is a 'further ohiect of this invention to automatically select signa-ling currents et' dii'i'erent frequencies to selectively signal dillerent stations on a transmission line.

An additional obj ect of the invention is to provide an in-iproved arrangement tor cna.- hling an operator to control the character ot a signal displayed at a distant point.

A further additional object of this in- 'vention is to provide that an originating' operator may control the` signals at successive distant switchingl points during); the hnilding up oit a so-called through connection -which control also includes the nianipnlation. oit the signal at the called station. toY indicate that the .callavas attended over a lone; distance or toll line.

fr still further object ot this invention is to provide that on a huilt-up connection, an. originating operator may so control the character ot the signals' displayed at each switching point as to indicate Whether the attention ot operators at such points is required, and also to operate: all of such sig'- nals simultaneously to indicate at the switching` points tl it the connection may he taken down.

A further additional feat-nre ot this invention to provide an improved system tor signaling' over a nun'iher oitl` types ot tele phone circuits Without the use of composite rangers. y

The 'foregoingand other objects ot this invention arc attained oy the provision in a link circuit oi switching, means, the operation ot which is dependent upon the characteristics ot the line terminals with which the link cooperates in establishing a connection. The position ot the switching' means determines the frequency of the' signaling currents available for' use on a connection. A liter the connection is established, the operator may canse asignal at a. distant ration to light steadily' or intermittently, under* control ot a ringing key. It the lrey is actuated tor' a prolonged interval aninterruptor is connected in series with the signaling current to; `the line, but itthe ring# ley is actuated inoinentarily` the signaling' current' is applied steadily to the linlr circuit independeni'ily' oi the interruptor.

The invention will' be readily I inderstoodi troi'n the following detailed description andy hy reference to the'` accompanying: drawings in which l shows a universal cord cuit adapted to cooperate directly Witli a snhscrihers line or indirectly therewith tl'irouggh a toll switching trank irirestahl'ishing a telephonie connection. `Figz 2 shows the' teri'ninals-oi three toll lines adapted to he connected individually either directly or indirectly with a sn'hscriloersjlin-e through the universal cord circuit shown in Fig; l;

lin order to describe the invention tail a toll call originating' at stationi-L'lilig.. l, will he traced throng-hy to the tollV sivitchboard position B, Fig. 2.. In accordance With. the well hnoavn practice, it may he assumed that a ticlret covering the details ot azcall originating at' station A has reached the toll' line operator at apositionat 'which cord circuit C is located. @ver an4 order Wire circuit, not shown, the operator thenV requestsconnectioir with station t from a toll switching operator `Who assigns the trnnlcT and insertsl plug l0 into jac'lt ll. Following this theline operator inserts plugv associated with the cord circuit C, into the ia-clit 13 ot the' assigned toll switching trunk T.

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hen a toll switching operator insertsr plug" l0 in jack ll, a circuit is established which may lre traced' troni grounded hattery, through the `Winding ot relay 520. sleeve contacts ot plug, V and jacl;` il, and thence to ,f ,fronnd through the Winding ot cutnotiI relay 2l. Relay 2O operates and. at its inner arniat i and baci; Contact, disconnects the lousy test lead BT troni the tip conductor ot the trunk T and, at its front contact, renders 'the tip conductor ot the trunk continuous'. At its outer armature and iront contact, relay establishes a circuit for supervisory lamp 22 which niay he traced troni grounded battery, through relay 24 over two circuits, one of which may be traced Jfrom grounded battery, leltt-hand winding of relay 24, conductor 29, inner break contacts of relay 30,' conductor 31,

upper right-hand windingot repeating coilv 32, tip contacts of jack 13 and plug 12, upper normal contacts ol key 33 and thence to ground through Vthe upper lett-hand winding ot repeating coil 34; the other eir cuit may lie-traced from grounded battery, winding oit relay 35,A conductor 35, lower lett-hand winding of repeat-ing coil 34, lower normal contacts of key 33, ring contacts ot' plug` 12 and jack 18, lower right-hand winding of repeating coil 32, conductor 37, outer break contacts et relay '30, conductor 38, and thence to ground through the righthand winding of relay 24.

Relay 24, in operating, interrupts the circuit for guard lamp 22 which is thereupon extinguished to notifyv the originating toll switching operator that the line operator has seized the proper trunk'l` in establishing the connection. In case the toll line operator, through error or otherwise, had tailed to take the assigned trunk T,'relay 24 would have remained inert and the continued glow of the lainp 22 would thus have indicated tor.

It is to be noted that upon the insertio-n of plug V12 into jack 18, relays 26 and 25 do not operate owing to the high resistance element 27 associated with the sleeve ot jack 13. Lamp 28 will nevertheless, due to the immediate operation of relay v35, be lighted over the following circuit: battery, lamp 28, armature and back contact of relay 26, armature and yfront Contact of relay 35 to ground. The glowingl of lamp 28 indicates to the line operator that. the connection has been made at the distant end orn the trunk circuit and that ringing inay be proceeded with. It now key 83 is actuated, the main conductors of the plug 12 are transferred from the right-hand portion ot the cord circuit C by way of the right-hand armature and back contacts ot .relay 25 to sources Vof alternating currents 57 and 58. Currents Jfrom these sources Vrnaynow traverse the main conductors of the trunk circuit T, right-hand windings of the repeating coil 32, thence to conductors 81 and 37, 72 and 73, and through a circuit completed through an associated condens-er and the windings ot relay 59. This relay 59 may be of any suitable alternating current type, but preferably ot the type disclosed in the copending application of H. lV. ONeill, Serial No.

this irregularity to the toll switching opera! 526,152, iled'Deceinber 31, 1921. Under the influence of these incoming alternating currents, the normally close-d contacts GO ot this relay 59 separate, and open the obvious circuit normally holding the relay 43 energized, causing this relay to release. Relay 48, in releasing, disconnects the righthand portion of the trunk circuit equipment, and applies ringing current from a source 61 by way of the main conductors of the plug 10 and jack 11 to the line oit station A. It is pointed out that current from the battery and ground connections at the relay 24 retain this relayv operated due to the loop path through the sources olf alternating currents 57 and 58 during the ringing period. To prevent the extinguishing ot' lamp 28 during this period, whenever such an arrangement isdesirahle, relay may be. maintained energized by closing a circuit therefor to ground through the makeA betere-break contacts Aot key The maintenance of relay 24 operated thus avoids lighting the lamp 22 at this time. rilhe sourcese57 and 58 supply current at respectively ditterent frequencies as required 'for operations, to be described hereinafter. In connection with the signaling ot the station-A., currents ot a single 'tre quency may be sufficient to operate relay 59, although this relay may be of a universal type relative to control through a wide range ot frequencies, and therefore respond to the joint effect of the sources 57 and 58.

On cessation of the ringing current from cord circuit C the resulting` restoration of relay 59 and the reoperation oit relay 43 disconnects the ringing current from line leading to station A and re-establishes the continuity of the conductors of the trunk. dien the subscriber at A removes his receiver from the hook, this re-establishing of trunk conductors permits a circuit to be traced from grounded battery,through resistance 41, winding o'f' supervisory relay 40, conductor 42, lower lett-hand winding ot repeating coil 32 and thence over the ring conductors through plug 10 and jack 11, the apparatus at station A, returning over the tip conductor, upper lett-hand winding of repeating coil 32, and resistance element 44 to ground. Relay 4() in operating, coinpletes a circuit 'from grounded battery through the right-hand winding et relay 30, the leithand winding of this relay to ground through the front contact and arinature of relay 24. Relay 30 a operates, switches the conductors 31 and 37 'from relay 24 and `ioins them. through a transmission condenser 9. In this position of relay 3() the windings of relay 24 are, however, joined locally to continue the energization of the latter relay, while the windings of relay 59 vare shunted by condenser 9. At the cord circuit C the resulting cessation ot direct llO ias-rami current Vthrough relay over the trunk circuit permits its release and the extinguishment of lamp 28, such lamp having been,

yline operator proceeds with the 4connection and inserts plug 14 into jack 15, and in so doing causes the operation of the sleeve relays 47,46 and 100 in an obvious circuit. Cut-off relay 100 in operating disconnects the regular line relay 1,01 from the line and prevents its operation at this' time. Relay i7 is marginal but the resistance of the cutoil relay 100 in series therewith is su'iicient-ly louT to permit relay 4-7 to operate. Vlhe operation of relay i6 performs no useful function in this case as relay 417, in operating, prevents, by the attraction of its outer left-hand armature, the lighting of lamp 48, which therefore does not enter into the operation of the circuit at this tin-ae.

Relay i7 also in operating connects a 16 cycle current source 55 to its armatures and upon the actuation of ringing key 56, current from the source 55 flows over a' path which may be traced through the armatures and front contacts of relay 47, outer contacts of ringing lrey 56, tip and ring contacts of plug let and jack 15, line conductors 104 and 105, and then through the left-hand Winding of relay 102 which bridges conductors 1011- and 105.

. versation between the subscriber at station i and the called subscriber may now taire place.

it the completion of the conversation, the subscriber at station A replaces the receiver on the sivitchhool; and inso doing interrupts the energizing circuit for relay 510, which relay retracts its armature thereby opening the energizingcircuit for relay 30. Relay 30 in deenergizing re-,establishes the energizing circuit for relay 35 which has been previously traced through relay 2li. Relay 35 in operating re-establishes the circuit for lamp 28, Lamp 28 in lighting informs the line operator of the termination of the conversation,

The line operator then removes the plug normal.

Relay 102 in operating establishes a circuit for lamp 1.09 which may he' 12 from jack 13 and, in so doing, causes the deenergizationof relay 241, `vhereupon circuit is established for lamp from grounded battery, lamp. 22, outer left-hand armature andfront Contact of relay 20, resistance element 2&3, bach Contact and armature of relay 2t to ground. Lamp 22 illuminates in this circuit and informs the toll switching operator that the period of conversation has ended and that the line oper-` ator has removed the plug 12'froin jack 13. The operator then removes plug 10 from jacl; 11 thereby restoring the apparatus associated with the toll switching trunk '.l to

To give a disconnect signal to the operator at position B,the line operator momentarily operates the ringing lrey56 to apply loiv frequency ringing current from the source over the line circuit. Assuming, as already mentioned, that a cord circuit similaito the cord circuit C is connected to jack 16 at position B, current will now ioiv through the relays in that cord circuit corresponding to relays 53, 68 and 54 of thel cord circuit C, but the relay corresponding to relay G8 only Will be energized to illuminate a supervisory lamp corresponding to lamp 70. The operator at position B will then actuate the listening .key 05 to ascertain Whether the connection is to be disestablished. lf now key of the cord circuit at position i3 is operated,` the holding circuit for the relay, corresponding to relay 68, is opened, causing the lamp, corresponding to lamp 70, tobe extinguished. The operator at position B may then disconnect thecord from the line circuit.

The `line operator Will then remove plug 1li from jack 15 whereupon the apparatus associated with the cord circuit C is restored to normal.

It Will nouv be assumed that a call originating at position B is intended for the subscriber at station D, the terminals of which are directly accessible to the line operator.

rfhe lineoperator Will in this case insert plug l2 into jack 75, the resistance of the sleeve of which is low. A circuit may then be traced Vfrom grounded battery, Winding of relay'25, Winding of relay 26, sleeve contacts of plug 12 and jack 75, and thence to ground through-the Winding of cut-oil relay 7 T he resistance. of this circuit is: low enough to permit the operation of marginal relays 25 and `20. The operation of relay 2S causes the 'lamp 28 to Vlight over an oio` viens circuit.

The response of the simscriber at station l) causes the operation of relay 35 over an ohvious circuit and thereby extinguishes lamp 28. This lainp will again be lighted when. relay 35 releases due to the restoration of the receiver tothe switchhook at station D. rThe establishment of this connection therefore differs from that estaliilished to the. @nibllO scriber A only in that, upon the operation of ringing key 33, the 16-cycle current source 71 is connected directly with the subscriber-s line D, due to the operation of relay 25, whereas in the previous instance, double frequency currents from the sources 57 and 58 were sent out over the toll switching trunk T, due to the non-operation of relay 25.

Having thus described the operation ot' the cord circuit C, first, when associated with a toll switching trunk having a high resistance sleeve terminal and a line requiring low frequency currents for signaling purposes. and second, when associated with a subscribers line having a low resistance sleeve terminal and a line requiring low frequency currents for signaling purposes, the following description will be directed to the use of the cord circuit C when the outgoing end thereof is associated with the line E which has a high resistance sleeve terminaland which requires a double frequen y current for signaling purposes.

To simplify the description, it will bey assumed that the plugs 2 and 14 have been inserted in the jacks 7 5 and 110, respectively. The effect of inserting` plug 12 into jack T5 has been described heretofore and neednot be repeated in this connection.

Upon inserting plug 14 into jack 110, a circuit is established which may be traced from grounded battery, winding of marginal relay 47, winding of relay 46, sleeve contacts of plug 14 and jack 110, and thence to ground through the winding oi' cut-off relay 111. The resistance of the winding oi cut-off relay 111 is sufficiently high to prevent the operation of relay 47 at this time. The operation of relay 46 effects in this instance, due to the non-operation of relay 4'?, the illumination of lamp` 48 over a circuit extending from grounded batter 1, armature and Jfront contact of relay 46, conductor 4S),

` armature and back contact of relay 50, lan'ip 48, and thence to groundl through the outer left-hand armature and back contact of relay 47 and the circuit controlling elements 51 and associated with relays 53 and 54, respectively. Relay 111 energizes in series with relay 46 and at its left-hand armature and back contact disconnects the relays 112 and 113 from the line conductors of the line E.

The line operator then actuates ringing key 56, whereupon currents of 1300 and 1700 cycles from the sources 57 and 58, respectively, traverse a path extending from the sources 57 and 58 over conductors 80 and 81, armatures and back contacts of relay 47, contacts of ringing key 56, tip and ring contacts of plug 14 and jack 110, line conductors 118 and 119 of line E, and thence through the windings of relays 120 and 121 which are normally bridged across the line conductors 118 and 119. Relay 120 is tuned to respond to 1800 cycle currents, whereas relay 121 will operate upon the application of 1700 cycle current to its windings.

It is to be noted that relay 122 is normally energized over a circuit which i'uav be traced from grounded battery, thence in parallel through the circuit controlling elements 123 and 124 of relays 120 and 121, respectively, to the point 125, through the left-hand armature and front contact of re lay122, and thence to ground through the winding of relay 122 so that relays 120 and 121 in operating upon the applicaiion of current from the sources 57 and respectively, to their windings interrupt this 'normally energizing circuit to eflcct the release of relay 122. Relay V122 thereupon retracts its armature which eects an obvious energizing circuit for lamp 126 located at position F.

In controlling the signal 126 to be steadily lighted, as above described, a single momentary operation only of the ringing key 56 is required. The present system provides that this signal may be intermittently ener gized through control from the cord circuit C. Itis readily seen that succeeding momentary'actuations of the key 56 will intermittently apply alternately currems from the sources 57 and 58 to effect the- relays 120 and 121 to correspondingly cause the flashing of signal 126. Such flashing may be at a relatively slow rate, whereas the signal may be flashing at a distinctly different rate through an interrupter 85, In the actuation oi' ringing lrey 56, the uppermost contacts apply ground over au obvious circuit to energize a slow-to-operate relay 86. Byrretaining the key 56 operated for a 'sufiicientlyvlong period, the relay 86 will respond and open at its armature and back contact a path normally shunting this interrupterv 85. In this case, the interrupter will'intermittently apply currents from the sources 57 kand 58 to relays 120 and. 121 to correspondingly flash signal 126. Thus, the signal at the distant end of the line may be operated in a number of ways to suit various operating requirements as will hereinafter be described.

The operator at position F, upon noting the illumination of lamp 126, inserts a plug associated withher cord circuit into jack 127, whereupon cut-off relay 128 operates effecting an energizing circuit for relay 122,-

which may be traced from grounded battery, frontcontact and armature ot relay 128.

and thence to groundthrough the winding ot relay 122. Relay 122, in operating, disconnectsthe line lamp 126. Relay 122, in operating, locks through its left-hand contacts to grounded battery at the normally closed contacts of relays and 121 to prepare the circuit for receiving another call after the disestablishment of the present call. The

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operated position of-the talking key of the cord circuit C during the passing of lthe call to the operator at position F,'closes a circuit frein grounded battery, contacts of relay 46, winding and right-hand normal contacts of relay 50 and the upper c. ntacts of key 65 to ground. Following the .Initial response of relay 50, the lead to the ground at key 65 is disconnected while the righthand forward contacts of relay 50 establish a self-locking circuit for relay 50, toy

ground through the normal contacts 51 and 52 of relays 53 and 54. This extinguishes the lamp 48. I

Upon learning the ,details of the call, the operator at position F proceeds to complete the connection and signal the called subscriber, after which conversationinay take place over Vthe established circuit. lt will now be assumed that the calling subscriber has hung up and that the line operator has received a signal to that'effpect. In response to the disconnect signal the line operator removes plug 12 from jack 75. The line operator thereupon actuates ringing key G whereupon 1300 and 170() cycle currents from sources 57 and 58 are sent out over theline E. These currents-operate relays similar to relays 53 and 54 of the cord circuit siinilar to the cord circuit C which is connected to the line E at position F. Upon the, actuation of relays 53 and 54, the holding circuit for relay is opened thereby lighting lamp 48 steadily, whichse'rves as a disconnect signal at the position F. 4 Assuming that the operator at position F during the existence of the connection, desires to attract the attention of the line operator she will apply 1300 and 1700 cycle current to the line E. Relays 53 and 54 of the cord circuit C respond to this current. The first impulse of current releases relay 50 to reconnect lainp 48. Succeeding inipulses of alternating` current, due to the flashing of the ringing key or to the operation of a device sin'iilar to the interruptor 85 at position F, result in corresponding interruptions of the contacts of relays 53 and 54 and correspondingly disconnectingF and thereby hashing of the lamp 48, as relay 50 will be released upon the first interruption of contacts 51 and 52. The receipt of. the flashing signal indicates to the line operator that her attention is desired by the operator at position F. Operation -of the talking key in going in on the connection will result in the energization of relay 50 to disconnect lamp 48 in the nian-ner previously described.

In seine exchanges, there are lines` terminating in a plurality of positions, some of said positions being accessible to attendants known as inward operators, while other positions are accessibleto known t.liroughl operators, and it 1S' Often desirable that an originating line operator be able foreach either of these types of operators. Ordinarily, a call is initially answered at an inward operators position.

Following the receipt of a request for connection with an operator located at another type of position, the inward operator may join the toll. line to an interoiiice or int-erposition trunk and thereupon herself signal the desired position or the answering operator may depress a transferkey whereby a signal will be displayed at the desired position, at which point the toll line rnay be accessible on ajinultiple basis. However, iinportant advantages may be secured by a pro vision, whereby an originating operator may f directly signal or select any desired different type of position or poi-nt in a distant exchange, and in the systeln according to this invention, provisions for such service have been made. lll/lith this'end in view, the following description is directed to the establishment of a connection bylineans of the lcord circuit C over the line L, the terminals of which are multiplied Vat one end in jacks 130 and 131 and at the other end in jacks 132 and 133, the jack 130V being located at an inward operators position and the ack 131 being located at a through operators position.

Assuming that the plug 12 has been in serted in jack 7 5 and that the line operator desires to signal the inward operator, she inserts plug 14 into liack 132, whereupon a circuit is established extending from 100 grounded battery, through. the windings of marginal relay 47 and relay 4G, sleeve contacts of plug 14 and j ack 132, and thence to ground through the right-hand winding of relay 135. Relay 135 in operating discon- 105 nects the line relays 136 and 1.37 from the line conductors 138 and 139 of line L. The right-hand winding of relay 135 is of such a resistance as to perniit the operation of relay 47 in series therewith.

The line operator 'then actuates ringing key 56, whereupon 16 cycle current froni the source flows out over the armatures and front contacts of relay 47, the front con tacts of ringing key 56, tip .and ring con- 115 tacts of plug 14 and jack 132, line conductors 138 and 139, and thence through the windings of relay 140, right-hand winding of relay 141 and the outer armature and back con- .tact of relay 142. Relay 140 is tuned to re- "120 spend to current of a frequency of 1700 cyclos, whereas rela-y 141 will operate upon the application of 16 cycle current to its winding. Relay 141 thereupon eiiergizes and establishes a circuit which inay be 125 traced from grounded battery, armature and Vfront contact of relay 141,; conductor 143,

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and thence to ground' throughthe'lamp` 144.

-A locking circuit for relay 141 is alS'O estabiisheaesanang eatery, 13o

mature and front contact ot' relay 141, leftliaiid winding ot relay 141, and thence to ground, through the inner back contact and inner armature of relay 142. The locking circuit just tiaced places relay 141 under thc control of cut-oit relay 142.

y VU )on noting the illumination 'of lamp 144, the inward operator inserts a plug associated with her cord into jack 130, whereupon the cut-ott" relay 142 becomes energized and interrupts the locking circuit for relay 141 whereupon the energizing circuit for lamp 144 is interrupted. Lamp 144 thereupon extinguished and line relays 140 and 141 are disconnected from the line. The inward operator then connects her telephone set with the line and is informeel by the line operator as to the details of the call, after which the line operator proceeds to complete the connection. y

A After conversation is completed and the receivei' at station D has been restored to the switchhook, lamp 28 will light. The line Y operator noting this signal removes plug 12 trom jack '75 and momentarily depresses ringing key 56 thereby applying` ringing current from the source over the lin-e circuit L. A relay similar to relay 68 will then be actuated tolight a lamp similar to lamp 70. Upon noting the illumination ot this lamp the inward operator actuates her talking key which disconnects" ground to release a relay similar to relay 68 which eX- tinguishe's the associated lamp.

It the line operator had signaled the through operator on line L, she would insert plug 14 into ack 133 whereupon a circuit is established extending from grounded battery, windings of relays 47 and 46, sleeve contacts ot plug 14 and jack 133, and thence to Oround through the right and left-hand t y windings ot relay 13o. Both windings ot relay 135 being included in this series circuit` the resistance is sufficiently high to prevent the operation oit relay 47. Relays 46 and 135, however, operate and perform the saine function as described in the previous The line operator then actuates ringing key 56, whereupon double frequency cui'- rents ot 1300 and 1700 cycles are intermittently connected through interrupter to the tip and ring conductors ot the line and traverse a path which may be traced over conductors 81 and 80, armatures and back contacts ot relay 47, contacts ot key 56, tip and ring contacts of plug 14 and jack 1253, line conductors 138 and 139 ot line L, and thence through the windings of relay 140 and the right-hand winding ot'ielay 141 which are bridgedacross the line conductors 138 and 139. Relay 141 being tuned to operate only on 1,6 cycle current is not altectedr by the application ot currents troni the sources 57 andA 58, whereas the 1700 cycle .current from 'the Scarce 58 effects they operation of relay 140, the 1300 cycle-'current from the source 57 being idly present at this time. Relay 140 thereupon operates and interructs the normal energizing circuit for relay 145 which may be traced from grounded battery, winding of relay 145, front contact and armature of relay 145, and thence to ground through the circuit controlling element 146 associated with the relay 140. Relay 145 is deenergized, retracts its armature and establishes an obvious circuit for lamp 147.

Upon noting the illumination of lamp 147, the through operator proceeds to answer thecall by inserting a plug corresponding to plug l2, Fig. 1, into jack 131 which effects the operation of cut-off relay 142 to extinguish lamp 147 by the operation ot relay 145 from a ground supplied at the inner armature and front contact of relay142. The through operator after having received the details of the call from the line operator then proceeds to extend the connection to and signal the distant called ollice Jfrom which point the desired subscriber may be reached in the well known manner.

` Assuming that a cord circuit similar to the cord circuit C is provided at the through operators position and at the distant called otlice, either ot' these operators may receive a disconnect or a call signal.

The disconnect signal results from the momentary operation of ringing key 56 in applying the high frequency currents to the line circuit. In cord circuits at the distant points equipment corresponding to relays 53 and 54 will cause relays, such as 50, to release and energize signals, such as 48.

The call signal results from retaining the ringing key 56 operated for a certain interval whereby the lamps corresponding to lamp 48 are flashed. It will be noted that with ringing key 56 actuated, a circuit is completed through the uppermostl contacts of key 56 for slow-to-operate relay 36. This relay in operating removes the normally closed shunt path around the interruptor 85, thereby causing the frequencies from the sources 5'7 and 58 to be intermittently applied to thc cord. As previously mentioned, this results iii-flashing the lamps at the distant points.

After completion ot conversation it will be obvious from the previous description how the connection may be released and the apparatus restoi'ed to normal.

lVhat is claimed is z 1. In a telephone system, a link circuit. adapted to intercoiniect lines of dillferent characteristics, acbridge associated with said link circuit comprising a plurality ot selectively responsive devices, a plurality ot nals controlled thereby, and means dependent upon the characteristics of' the line with whichv said link circuit is associated for selectively controlling said signals.

'2. -l-ii telephone System, theV combina- Cal llt)

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tion ofV a link cincuit adapted to interconnect linesot different types, a plurality of signaling means, a relay dependent for its operation on,` the typeot line associated with said link: circuit for controlling someV ot' said signaling means,- and a bridge zssociated with said linie circuit comprising a pluraity et selectively responsive devices for controlling ally et snide signalingmeans, scmeotsaid devices operating independently of the operation oli said relay te control the operation of some of said signaling means.

3. In a telephone systema link circuit adapted to` intenconnectlines ot different types, a plurality of signaling means, a plurality of current sources of different characteristics, a relay operative when said link circuit is associated With one type of line to connect one of said current sources to said link circuit and inoperative when said link circuit is associated with another-type of line to supply said link circuit with current from another of said sources, a plurality of devices associated with one type ot line responsive to currents of one characteristic to control a corresponding signaling means, and a plurality of other devices associated with another type of line selectively responsive to currents from corresponding sources to control said signaling means.

4. In a telephone system, a link circuit` adapted to interconnect lines of dilferent types, signaling means, a bridge associated with said link circuit comprising a plurality of selectively responsive electromagnetic devices, a plurality of current sources of ditferent characteristics, and means dependent upon the type of line associated with said link circuit for selecting a current source to selectively actuate some of said electromagnetic devices whereby the operation ot said signaling means is edected.

In a telephone system, alink circuit, a line, a plurality of operators positions on said line, signaling means at each of said positions,responsive to currents of different frequencies, and means associated With said. link circuit auton'iatically selected when the link circuit is connected to the linel ior lectively actuating said signaling means to signal the operator at one of said positions.

(i. In a telephone system, a line, a link circuit, a plurality of operators positions Von said line, a bridge on said line including selectively responsive relays, a plurality ot current sources of drlferent characteristics associated with said link circuit, and means `associated With said link circuit for automatically selecting and for connecting one ot' said current sources to said line to selectively actuate one of said relays to signal an operator at one ot said positions responsive to the connection of said link circuit to said `line at a corresponding operators position.

fr', *In ateleplione system, a ,link Cluit, a

said` sources of currents simultaneously to.

said link; circuit to variably actuate said signal:

Si In a telephonesystem, a link circuit, a trunk circuiti, al, signal, sources of alternating currents, a, key forv said: link circuit,

means opena` ve inresponse to a centaii'i` actuation of said key ton applying current tromV alli-ot 1 saidgsources to said link and trunk circuits to actu-ate said@ signal in one manner, and means operative in response to another actuation of said key for applying current from all o said sources to said link and trunk circuits to actuate said signal in another manner. p

9, A universal cord circuit comprising a relay at each end thereof, a plurality of current sources adapted to be controlled by either one ot said relays so that a certain of said current sources is available ttor use when either one of said relays is in one position and so that other sources are available 'or use when either one of said relays is in the opposite position.

l0. In a telephone system, a link circuit, a line adapted'to be connected thereto, a signal associated with said line, a source of alternating current and a manual switch in said link circuit for connecting said source to the link circuit to operate the signal in a continuous manner, and means responsive to the operation of the switch for a certain period for connecting said source in an interrupted manner to the link circuittor a corresponding operation of the signal.

ll, In a telephone system, a link circuit, a signal, a source of current, means for connecting said source of current to the link circuit comprising a key, a relay, and an interrupter, normally short-circuitcd by contacts of said relay, so arranged in a circuit that when the key is operated. for a limited period the relay is not operated and i the source ot' current is connected to the link circuit in acontinuous manner, whereas it the key is operated a comparatively longer period the relay is operated and the interrupter thereby arranged to alternately connect the source to and disconnect it from the link circuit for a corresponding opera tion of the signal. Y'

12. In a telephone system, a cord circuit, a trunk circuit, two signals associated `with said trunk circuit, a plurality of sources of current in said cord circuit, means tor connecting the cord circuit and the trunk circuit at two diirerent points of the trunk circuit, means yin said. trunk circuitl for making a source of current ot one character available tor. Operetten et one Vsignal in said lll() trunk circuit when the cord circuit is connected at one point to said trunk circuit and for making a source of Current of a different character available for the operation of the other signal in said trunk Circuit when the cord circuit is connected to the other point of said trunk circuit, and means in said Corel circuit for causing" the operation of either one of said signals responsive tok the connection of the cord circuit to the corresponding` point of the trunk circuit.

13. In a telephone system, subscribers lines, a trunk circuit, a cord Circuit adapted to be connected to either the trunk circuit or a subscribers line, sources of current in said cord circuit, means for making a source of one character available for ringing purposes responsive to the connection of the cord circuit to the trunk circuit, and means for making a source of current of a different character available for ringing` purposes responsive to the connection of the cord eirouit to a subscribers line.

In Witness whereof, I hereunto subscribe my name this 25th day of November A. D.7 1922.

HENRY IV. ONEILL.

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