US1214492A - Telephone system. - Google Patents

Description

A. H. DYSON.

TELEPHONE SYSTEM.

APPLICATION F|LED APR- 6, I906.

Patented Jan. 30, 1917.

3 SHEETS-SHEET I.

A. H. DY SON. TELEPHONE SYSTEM.

VAPPLICATIDNFILED APR.6,1906.

Patented Jan. 30, 1917.

3 SHEETS-SHEET 2- A. H. DYSON.

TELEPHONE SYSTEM.

' APPLICATION FILED APR- 6. [906. 1,214,492. Patented Jan. 30,1917.

3 sucns-snzcr a.

" Chicago,

UNITED s'rnrns PlgrE 'r OFFICE.

ALFRED H. DYSON, F CHIGAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO KELLOGG SWITCHBOARD & SUPPLYLOMPANY, A CORPORATION OF ILLINOIS.

To all whom it may concern:

Be it known that I, ALFRED H. DrsoN, a citizen of the United States,and resident of county of Cook, and State of Illi nois, have invented anew and useful Improvement in Telephone Systems, of which the following is a specification.

bridge between the line limbs The present invention relates to automatic' telephone'exchange systems in which suitable step-by-step switching mechanism is operated in response to impulses sent over a calling line to automatically select and establish connection with a desired called line and is automatically restored to'normal position at the end of conversation.

The-invention has to do with a system in which the talking circuit is completed through the agency of repeating coils and it includes a novel circuit arrangement in such a system for disconnecting connected parties and restoring the parts to normal position and also novel means for completing the talking circuit between two stations only.

\ bank contacts 18--19 of a plurality of conafter a called party responds to the call.

The nature of the invention will be more fully understood upon reference to the following detailed description and the accompanying drawing which illustrates three and the scope of the 1 forms of the invention, invention will be particularly pointed out in the a pended claims.

cordance'with my invention; Fig. 2 is a similar diagram of a modified form thereof;

Fig. 3 is a diagrammatic illustration of a further modification; and Fig. t is a diagrammatic illustration of the type of switch employed in the systems illustrated.

Throughout these several views, like charactors refer to like parts. y

Referring to the drawing in detail and for the "present to Figs. 1 and beach substation, of which the substation A only is illustrated,

is providedwith the usual condenser 10 and call'bell 11 included in a normally closed S-P, and controlled by the switch-hook 12, and the usual trairsmitterlii included in normally open bri e also controlled by the switch-hook 12.

In this instance, one winding of an induction coil 14 is included in this normallyopen brid e andtlic receiver 15 is included n a lace eireiiit with its other" winding. The

substation is further provided with means tor sending current impulses over either line limb separately, for establishing, metallic connection between the line limbs and for grounding both line limbs simultaneously, as will more fully appear hereinafter. At the exchange, the line limbs terminate in the multiply connected fixed contacts of a plurality of electromagnetically actuated switches commonly called connectors and in the movable contacts of a single electromagnetically actuated switch commonly called a selector. The fixed contacts of the selectors are, connected to movable contacts. of the connectors through the agency of linkcircuitsprovided with repeating coils for inductively uniting their parts for conversa tion. Inf'operation, the selector of a calling line is actuated to select one of a number of linkrircuits extending to a "group of connectors to which the called line is connected. In the present case, the line limbs S and l? terminate in the multiply connected fixed or 2 0 and 21 and the repeating coil BC to the movable contacts or wipers 16-17 of a con-- nector having access to the desired line. Any desired type of electro'magnetically actuated switch may be employed to perform these selecting and connecting functions. For the purpose of making theoperation of the system intelligible, I have illustrated con ventionally in Fig. t a "type of switch which may be employed to perform these functions. This switch, which may be assumed to be a selector, comprises three movable contacts or wipers 16, plurality of fixed contacts 18', 19' and 23' respectively, which are arranged in banks of preferably one hundred contacts per wiper. For the purpose of moving the wipers into engagement with the desired bank contacts, they are mounted upon a shaft 24 which is given a primary or longitudinal step-by-step movement through the agency ofa coopcratin rack 25 and an actu ating pawl 26 operate by the armature of the primary actuating magnet PM. 'The retaining pawl 27 cooperates with-a rack 28 on the shaft to hold it against return. From 17 and. :22, which have access to a i this it will be seen, that the Wipers may be stepped to any desired level or row of bank contacts. The shaft is given a secondary or rotary movement through the cooperation of a rack 29 and pawl 30 actuated by the armatureof the secondary'actuating magnet SM, and the shaft-is retained in its difi'erent operative positions by a retaining pawl 31 engaging a cooperating rack 32, the racks 29 and 32 being mounted so as to partake of the rotary movement of the shaft while permitting its free longitudinal movement with reference thereto. From this it will be seen that after having moved the wipers to the desired-level, they may be moved to the desired bank contacts by the repeated ener gization and deenergization of the secondary magnet SM.

Associated with the switch mechanism is a control switch C, which is adapted to be moved into three different operative positions in response to the return movements of an armature 33 acted upon by the control magnet CM, the armature of the secondary magnet SM and theretractile spring 34. A retaining pawl 35 holds the swltch C in its various operative positions. For the purpose of returnin the parts to normal position, a release ar 36, carried by the armature 37 of the release magnet RM, is provided. Upon the energization of this magnet, the armature 37 is drawn against the tension of its retractile spring 38 so as to bring the teeth 39 on the bar into en-.

gagement with the ends of the. retaining pawls 27, 31 and 35-.

14With the parts in this position, as soon as'the release magnet RM is deenergized, the retaining awls are all thrown out of engaging ositl and both the switch C and the sha 24 are returned to their normal positions, the latter through the agency of gravity and the spring 40. The retaining pawls 27, 31 and 35 remain in their non-engaging posltions until the arma ture of the primary magnet PM is again energized. At this time, a portion of the armature engages the free, end of lever 36 and rocks the latter out of engagement with the pawls, thus allowing them to return to their engaging positions. ,A sprin 41 acts upon the lever 36 in op ositionto. t e arma-- ture of the magnet P The shaft 24 also controls anauxiliary switch B. y

\Viththe above brief outline ofthe system and the electromagnetically operated connecting switch mechanism as introductory, the operation of the system in detail will now be'considered.

Assuming that a party at substatioxi A desires to converse with a party at some other station connected with ,the exchange, and

assuming that the number of the latter's telephone is 234, he will first remove the receiver 15 from the hook 12, thereby completing a connectlon between the line Emil the cooperating sprin 47 twice, thereby completing a circuit rom ground at 48, over the line limb P, through the movablecontact 49 of the control switch C, the winding of the primary relay PR, normal contact 50 of the cut-off relay CO to the live pole of the batter 51 at the exchange, thus energizing and eenergizing the primary relay PR twice. This relay, byits contacts 5253, controls a circuit from ground, 5 through the back contact of the control switch actuating magnet CM, through the winding of the primary magnet PM to the live pole of the battery, thus energizing the magnet PM-twice and causing it to step the shaft of the first sel'ectorup so as to bring its wipers to the second level of the bank contacts. Thetwo impulses sent over transmitted over this circuit causes the sec- 10' ondary relay SR, through the agency of its contacts 53 and 57, to close a circuit from ground, through the winding of the control switch magnet GM to the live pole of the battery. This causes the attraction and 11 retraction of the magnets armature, which steps all the movable contacts of the control switch C to their second position. The

movement. of the contact 58-of this switch to its second position completes a circuit from 11 ground at said arm, through the winding of the secondary magnet SM to the live pole of the battery 51. This circuit also includes the normally closed contacts 59 which are broken in response to the energization Of 'I Z said magnet SM, thus producing a repetition of makes and breaks with resultant attractions and retractions of the-larmature of the magnet by which the shaft 24 of the selector is given its secondary movement. 12 Thus, the wipers will be stepped around over the contacts in the selected level and this movement will continue until an idle" i-Olltflft is encountered.

.Ls will more fully appear hereinafter, all 13 busy contacts ehcountered by the wiper 22 are connected to ground, and consequently,

as long as the wiper 22 is in engagement with such a grounded contact, there will be a closed circuit from the live pole of the batte'ry 51, through the winding of the control switch magnet CM, the contact 60 of the control switch C, the winding of the release frclay RR, the wiper 22, the encountered contact 23 to ground. This circuit will energize the magnet CM sufiiciently to attract its armature and hold it in its attracted positipn. At this point, it may be noted that the magnets CM and RR, are so constructed that when thus included. in circuit the former will attract its armature and the latter will not. As long as the armature 33 of the magnet CM remains attracted, the movable contacts of the switch C will remain in their second positionand the secondary magnet SM will continue torotate the shaft 24. However, as soon asan' idle bank contact 23 is encountered by the wiper 22, the circuit just traced willhe broken and the armature of the magnet CM Willbe returned to its retracted position and, in. sodoing, will move the movable contacts of the switch G to their third and final. positions, thus breaking the circuit of the secondary magnet ,SM and thereby discontinuing further movement of the wipers, connecting the wiper 22 to ground at the contact 60 and completing the dicate that the line S-P is busy.

Having thus selected an idle link-circuit of the desired group corresponding to the digit 2 of the number 234, the remaining impulses transmitted from the substation will operate. the connector to whose wipers the selectdlink-circuit is connected. Thus, upon the calling party moving the disk 43 until pm the contact spring 45 and aliowi'n thetlisk to return, three impulses will sent ovcr the line P from ground at the substation, through Wiper 16,

connected contact 18', a portion of the linkcircuit strand 20, the normal contact 61 of the relay 62, the win of the primary relay PR to the live p0 e of the battery.

The three impulses transmitted over this oil cuit will energize. and denergize the primary relay three times, each time makine;

and breaking a local .circuitfrom ground,

through relay contacts 63-454, normal contact 65 of the control switch magn CM, the contact arm 66 of the control switch 0',

through the winding of the primary magnet PM to the live pole of thebattery 51. This will cause primary magnet PM to move the shaft 24' so as to bring the wipers to the third level or row of stationary contacts.

The single impulse over the line limb S, following the' three impulses over the line P will com lete a circuit over the line S,-

Ithrough t e wiper 17, connected contact 19-,

a portion of the strand 21, the normal contact 67 of the relay 62, the winding of the secondary relay SR to the live pole of the battery 51, and the resulting engagement of the contacts 63 and 68 of this relay Willclose a momentary circuit through the control switch magnet GM and thus cause its armature to be attracted and retracted once, the retraction moving the arms 49, 55', 60' and 66' of the control switch C to their second position. The final four impulses transmitted over the line limb P from, the substatiomwill momentarily energize the primary relay PR four times in the manner previously described and cause four impulses of current to'be transmitted through the secondary magnet SJ. thereby stepping the wipers of the connectoraround four steps,

tacts of the called line. The. single impulse over the line limb S, followin the four im pulses over the line limb P, c oses a circuit through thecontrol switch magnet'CM in the manner heretofore described and causes said magnet to attract its armature which,

upon release, movesthe contacts of the control switch C to their thirduand final position. By the movement of the contact 60 of the control switchC to its third position, the wiper22' of the connector is grounded and a circuit is completed thereby from the live pole of the battery 51, through the winding of the cut-oil relay CO and switch B of the called line, and the connector contacts 23 and 22 to ground. The closing of this circuit a-ctu-ates the cut-oil relay to disconmeet the windings of the primary and sec- .and establishing connection with the conondary relays of the called line from battery,

thereby preventing subsequent operation of the selector associated with the called line.

Having thus established connection between the calling and called lines, the party at substation A depresses the key 69 to ring the bell of the called party. By this-act, he closes a circuit from ound at the substation, over line limb through the winding of the primary relay PR ;and the latter, in response thereto, com letes a circuit from ground through t e contacts 63-64, normal contact 65 of the v control switch magnet GM, contact 66 of the.control switch C and winding of the generator relay GR to the live poleof the battery 51. The closing of this circuit sufficiently ener gizes the latter relay to connect the terminal's of the generator G in circuit with the tion' with the strand 21 at the called stationcalled line, thereby sendin current throu h the call-bell ofjthecalled, is

subscriber.

soon as the called party removes his receiver from its hook in response to' the call, he inetallically connects the line limbs runmng to his station and thereby com letes a circuit for battery current throug the windings of the role 62 which controls the continuity of the lin -circuit strands 20 and 21 by means of its contacts 61 and 67. This circuit may be traced from the live pole of the battery 51, through conductor-70, winding 71 of the relay 62, to its connecsideof the repeating coil RC, thence over said strand, wiper 17,1 ine limbs of the 'called line, wiper 16', a portion of the strand vthe contacts of the relay 62 and remains in this condition until the called partly answers the call. Y Such afisystem 1s particularly well adapted for use with pay substation devices.

In the formof the invention illustrated in Fig. 1, the release relay RR, which controls the supply of current to the release .magnetRM of the connector, has two differentially arranged windings 73-74 connected respectively between the live and grounded poles of the battery 51 and the link-circuit strands 20-and 21 at points between'the repeating coil windings connected therewith. This relay is preferably made non-inductive so as to present no interference to speech transmission. During connection, the windings 73 and 74 of the relay RR neutralizes each other, and the relay contacts remain separated. N.ow, if the calling party firsthangs up his receiver at the end of conversation, the contact springs 75 associated with his switch hook will be moved into engagement, thereby grounding both line limbs S and P and thus destroy ing the balance between the windings 73 and '74 sufficiently to .cause the relay BB to close its contacts to complete a circuit from the live pole of the battery 51, throughthe release magnet RM ,-contacts of the relay RR, selector bank contact 23, wiper .22, the winding of the release relay RR of the selector, to ground through the contact 60 of the control switch C. The completion of this circuitwill momentarily energize the release magnet RM to cause it to attract and retract its armature, thereby-rerleasin the retaining pawls of the connector and a lowing it to return to its normal porelease magnet of the selector and removing its retaining pawls to allow it to return to its normal position. In case the called snliscribe'r first hangs up his receiver. the circuit, by which the'release relay NR willv have the balance of its windings 733 and. H destroyed, will extend over the line limbs 'of the called subscriber, rather than the link-circuit strands 20 and 2-1 :nnl' lln. liin: limbs S and P of the callingsubscriber,

Returning to that point in th cpvrnlion 3 at which the'wipers of the SAlri'llH are abnnl. to engage the bank contacts of thrmilcd line, if said line he inuse than. upon the ongagement of the wiper 22 of the connector with the bank contact 23 associated with said station, a connection to ground will be established, either by way of the control switch contact 60' of the connector pre\-'i.onsly connected to said line or by way of the grounding switch B of the selector of said line. Since at this time the movable contacts of the control switch C will occupy their intermediate position, a path for current will be completed from the wiper 22, through the contact 60 of the control switch (1 and the conductor 76 to the normally open contacts 77 of the control switch magnet (1M With the parts in this position, the final current impulse from the calling station over the line limb S, by which the control switch magnet CM is energized, will cause the contacts 77 to be momentarily closed, thereby completing a circuit from the live pole of the battery 51, through the release magnet.

RM contacts 7 7 of magnet CM. conductor 76, switch arm 60 of the control switch C and wiper 22 over the connected bank contact to ground, thus energizing the release magnet RM to cause the restoration of the connector switch'to its normal position in the manner heretofore described. The selector, however, will remain connected with the link-circuit strands 20%21, and as soon. as the calling party depresses the key 69 to apply ringing current 'to the called line, he will instead complete a circuit over the line limb P, through the primary relay PR and thereby momentarily energize the said relay to complete a momentary. circuit through the primary magnet PM, thus stepping up the shaft 24*. of the connector one or more steps, according to the number of times the. substation switch 69 is closed. As'soonas the first step is reached, a projection 78 on the shaft 24 closes switch contact 79, which zcs relay PR completes circuit from the interrupter 80,

which is instrumental in producing a busy signal in the" receiver 15 of the calling party. The interrupter is included in a local clrcuit including one winding of an induction coil 81 and the battery 51. The other winding of the induction coil 81 isincluded in a secondary circuit including the condenser 82, switch contacts 79, normal contact 61 of relay 62, link-circuit strand 20, selector switch contacts 18-16, line limb P, switch-hook 12, one winding of the induction coil 14:, transmitter 13, normally closed contacts 42, line limb S, selector switch contacts 17-49, link-circuit strand 21, normal contact 67 of relay 6%, winding oi. the secondary relay SR back to the induction coil 81. A shunt path is also provided from the normal contact 61, through the winding of the primary Upon observing the busy signal, the calling party will restore his receiver to its switch-hook and thus ground both line limbs S-P, thereby momentarily completing circuit through the windings of. both the prii'nary and secondary relays PR and of the connector, thus bringing together the contacts 83 and 84 and thereby completing a circuit from the live pole of the battery 51, through the release magnet RM contacts Sh -83, selector contacts 23'-y22, release relay RR- of the selector and through the contact of the control swfitch C to grouni'l. thus energizing the release magnets of both the connector and selector and cansing them to return to normal position.

From the above it will beseen, that I'have devised an automatic telephone system in which. repeating coils are used in the linkcircuits for transmitting speech between connected stations. Transmission current is supplied from the central battery 51, through tl1c windings 73 and 74 of the release relay RR topoints intermediate of the sections of the repeating coil windings associated with the link-circuit strands 20 and 21, respectively. From these points, the circuit of the calling party is completed through -sections of the re )eatin coil windin s. h L" strands 20-21, selector contacts 1618- and 17-19f and over the line limbs S P. From the same points, the circuit of the called party is completed through the other sections of the repeating coil windings strands 2021,.wipers l6-17 ofthe connector and i the connected bank contacts over the called line. Thus, two independent circuits are establislmd. each il'nzluding the 'co-acting windings of the repeating coil RC. As previously indicated, the relay RR is made non-inductive, since it is-included in the tall:- ing circuits of the two stations.

Obviously, in carrying out my invention, other circuit, arrangements may be employed without departing from the spirit and scope of the invention. In Figs. 2 and of the ac companying drawing, I have shown modified arrangements. 1 I

Fig. 2 is, in general, the same as Fig. 1,

and therefore need be described-only sulfi ciently to bring out the differences in arrangement and operation. In this instance, the link-circuit strands 20 and 21 are made up of two sections which are conductively independent of each other, and one section of these strands isnormally discontinuous as heretofore described. Each section of the spectively. Each of these is provided with two diflerentially arranged windings which are included in the connection between the opposite poles of the battery .51 and the linkcircuit strands; and'relay 88, having cum'illatively arranged windings, is also associated with the called sectlon of the link-' circuit and" has its wihdings included between the opposite poles of the battery 51 and the strands 20 and 21 of said'section of the link-circuit. Preferably, the windingsof the relays 87 and- 88 are includedin series, as illustrated. The relay 88 controls vthe continuity'o'f thev strands 20 and 21' in the same manner as the relay 62 of Fig. 1.

The release relay 86 likewise controls a circuit through. the release magnet BM in the same manner as the release relay RR of Fig. 1, but in this instance, it is-under the sole control of the calling party, While the relay Slander the sole control of the called party controls a grounded branch leading from the release magnet RM In the operation, connection withthe desired line is obtained in the" manner heretofore described inconnection with Fig. 1, and the party is rung up in the same manner. U on responding to the call, the removal 0 his receiver frpm its hook will complete a circuit from the live pole of the battery 51, through conductor 70, the lower windings of the re-.

lays 8788, the right hand section of theupper windings of the relays 88-437, to

ground. By reason of thedifferential arrangement of the windings of the relay 87, its contacts will remain in normal open position; and by reason of the cumulative arrangementof the "windings of the relay 88 i said relay uvill. attract, its armatures an ,1

thus render the left hand sections of thelink-circuitstrands 20 and 21' continuous. Conversation may then be held over the conductively independent circuits, inductively united by the repeating coil RC, as

will momentarily ground both limbs of the line and thereby destroy the normal balance between the windings of the relay 86 and cause'the latter to attract its armature to complete a circuit from the live pole of the battery 51, through the release magnet RM of the connector, the selector contacts 23 -22 and the release relay RR of the selector to ground at the contact arm of the control switch 0, which will cause both the selector and connector to return to normal position in the manner previously de-' scribed. If the called party hangs up his receiver first, by momentarily grounding both limbs of his line he will destroy the normal balance between the windings of the relay 87 and thereby cause it to attract its armature and complete a circuit from the live pole of the battery 51, through the release magnet RM? of the connector, to ground. This will release the connector and cause it to return to its normal position.

The subsequent restoration of the receiver of the calling party to its hook will simultaneously ground 'both limbs of the lines SP and thereby energize both primary and secondary relays PR SR and cause an engagement of the contacts 8384 to complete a circuit through the magnets RM and RR to cause the restoration of the selector to its normal position. In other respects, the operation of this form of the invention is substantially the same as that heretofore described.

In Fig. 3, the link-circuit strands 20' and 21' are divided into sections which are inductively united by means of repeating coil RC but the condensers 85 of Fi 2 are omitted and the windings of the re ays 86 and 87' are connected in series with the sections of the windings of the repeating coil, as clearly illustrated. Thus, between the sections of the repeating coil winding asso- 'to the right hand section of the ciated with the calling end of the linkcircuit, are included the windings of the release relay 86 and the battery 51, while between the sections of the winding of the repeating c'oil associated with the called end of the link-circuit, the windings of the relay 87 and the battery 51 are included in circuit. In this instance too, thewindings of the relay 88 are connected on the one hand, link-circuit, and on the other hand to the opposite poles of the battery 51 directly, instead of in series with the windings of the relay 87, as the windings of the relays 87 and 88 are connected in Fig. In operation, the connection of the calling and called lines is accomplished as heretofore described, and the removal of the receiver of the called party from its hook energizes the relay 88, as before, to complete the continuity of the linkcircuit strands 20 and 21, and at the same time supplies current to the windings of the relay 87'. The windings of the relay 86 are also supplied with current as soon as the relay 88' is actuated to complete the strands 20 and 21, but the relays 8687 are not actuated by the current thus supplied, since their windings are balanced, as before described. The balance between these relay windings is destroyed to complete. a circuit through the release magnets of the connector and selector in the manner previously described in connection with Fig. 2,

' by the terms of the appended claims allsuch alterations and modifications.

' I claim e 1. A telephone exchange system comprising telephone lines extending from substations to a central station, link-circuits at the latter station for uniting said lines, repeating coils included in said link-circuits for inductively uniting parts. thereof, switching mechanism controlled from a callin station for connecting calling and called lines to opposite ends respectively of one of said linkcircuits for conversational purposes, disconnecting means independent of said repeat ing coil under the subsequent control of each of the connected parties for destroying the established connection and restoring all parts to normal, a central source of current and means controlled by the response of the called subscriber for bridging said source across the callingline and placing said dis connecting means in operative relation with said calling line. I

2. A telephone exchange systemcomprising telephone lines extending from substations to a central station, link-circuits at the latter station for uniting said lines, repeating coils included in said link circnits for inductit'ely uniting parts thereof, switching mechanism controlled from a calling station for connecting calling and called lines to opposite ends respectively of one of saidlinkcircuits for conversational purposes, means for destroying the established connection and restoring all parts to normal comprising a differential electromagnct"haiing its windings normally balanced, and means at each connected substation for destroying saidbalance to cause-the restoration of the parts to normal.

3."A telephone exchange system comprising telephonelines extending from substations to a central station, link-circuits at the latter station for uniting said lines, repeating coils included in said link-circuits for in u ing the established connection and restoring all parts to normal, comprising a diiferential electromagnet having. its windings ineluded between the opposite poles of said source of current and the included link-circuit strands respectively, and means at each substation for varying the normal current flow in one of said windings to cause the restoration of the parts to normal.

4. A telephone exchange system comprising telephone lines extending from substations to a central station, normally electrically-discontinuous link-circuits at the latter station for uniti said lines, repeating coils included in said link-circuits for'inductively unitin parts thereof, switching mechanism contro led from a calling station for connecting calling and called lines to opposite ter station for unitin ends res a centre source of current and means independent of said re ating coil under the con trol of the calle arty for bridging said source across the ca ling line and rendering the included link-circuit continuous thus completing the-talking circuit between the two substations.

5. A telephone exchange system comprising telephone lines extending from substa tions to a central station, normally electrically-discontinuous link-circuits at the latter station for uniting said lines, repeating coils included in said link-circuits for inductively unitin'gparts thereof, switching n1echanism controlled from a calling station for connecting calling and called lines to opposite ends respectively of one of said link-circuits,.and means independent of said repeating coil, comprising an electro'magnet included in circuit'with the called. station, for supplying talking current to the calling line and rendering the included link-circuit continuous so as to complete a talking circuit between thetwo substations.

6. A telephone exchange system. compris' ing telephone lines extending from substations to a centralstation, normally electri cally discontinuous link-circuits at the latsaid lines, repeating coilsincluded in said ink-circuit for inductively uniting parts thereof, switching mechanism controlled item a. callin station for connecting calling and called lines to oppoivelyof one of said link-circuits,

site ends respectively of one of said links circuits, and means independent of said'repeating coil, including an electro-magnet connected'in bridge of the talking circuit at the called station side of the link circuit re- 'pc'ating coil, for rendering the included link-- circuit continuous so as to complete the talking circuit between the two substations.

7. A telephone exchange system coin Trieing telephone lines, extending from $11 stations to a central station, normally electriter station for uniting said lines, repeating coils included in said link-circuits for inductively uniting parts thereof, switching nieclh anism control-led from the calling station for connecting calling and called lines to opposite ends respectively of onset said linlc circuits, means under the subsequent control of the called party for changing the connections of said link-circuit to render the same continuous and supply talking current to the calling line,: and disconnecting means independent of said repeating coil. under the subsequent control of the connected par ties for destroying the established connection and restoring all parts'to normal;

8. A telephone exchange system comprising telephone lines extending from. substations to a central station, normally electrically-discontinuous link-circuits at the latter station for uniting said lines, repeating coils included in said link-circuits 'for in ductively uniting parts thereof, switching mechanism controlled from the calling station for connecting calling and called lines to opposite ends respectively of oneof said linkcircuits, means under the subsequent control of the calledpartyfor rendering the included link-circuit continuous and thus completing the talkingcircuit between the two substations, and disconnecting means for destroying the established connection and restoring all. parts to normal comprising a differential electroinugnct connected in bridge of the talking cirwit and under the subsequent control. of the connected parties.

9. A telephone exchange system comprising telephonelines extending from substations to a. central station, normally electrisally-discontinuous link-circuits at the lat ter station for uniting said lines." repeating coils included in said linlccircuits for inductively uniting parts thereof, switching mechanism controlled from the calling tion for connecting callingiand call; lines to opposite ends respectively of one said link-circuits, a source oi current, a re M for controlling the continuity of the included link-circuit having two energizing windings connected respectively between the opposite poles of said source of current and. said link ircuit strands at the called station side of the link-circuit repeating ,coil, and disconnecting means for destroying the established 1 cally-discontinuous link-circuits atthelatcomprising a diflerential relay having its windings connected respectively between- "the opposite poles of said-source of current and the link-circuit strands. i I 10. A telephone exchange system comprising telephone lines extending from substations to a central station, normally electrically-discontinuous link-circuits at the lat ter station for uniting said lines, repeating coils included'in said link-c rcuits for inductively uniting parts thereof, switchingmechanism controlled from a calling st a, tion for connecting calling and called linesto opposite ends respectively of one of said link-circuits, a source of ringing current as-.

sociated with the included link-circuit, means under the control of the calling party to connect said source in circuit with the called substation, means dependent upon the response of the called party for supplying talking current to the calling line and rendering the included link-circuit continuous and thus completing a talking"circuit between the two substations, and means independent of said repeating coil for destroying the established connection between said calling and called lines.

11. A telephone exchange system comprising telephone lines extending from substations to a central station, normally electrically-discontinuous link-circuits at the latter station for uniting said lines, repeating coils included in said link-circuits for inductively uniting parts thereof, switching mechanism controlled from a calling station for connect ing calling and called lines to opposite ends respectively of one of said link-circuits, sources of battery and ringing current associatcd with the included link-circuit, means under the control of the calling party to connect said source of ringing current in circuit-with the called substation, a relay for controlling the continuity of the included link-circuit having two energizing windings connected respectively between the opposite ,poles of said source of battery current and said link-circuit strands at the called station side of the link-circuit repeating coil, whereby the completion of the talking circuit between thetwo stations is dependent upon the response of the called party, and means independent of said repeating coil for, restoring said switching inechanisml 12. A telephone exchange system comprising telephone lines extending from substations to a central station, normally discontinuous link-circuits at the latter station for uniting said lines, repeating coils in cluded in said link-circuits for inductively uniting parts thereof, switching mechanism controlled from a calling station for'connccting calling and called lines to opposite ends respectively of one of said link-circuits for conversational purposes, a ringing key device, means for indicatin at the calling substation a busy signaling.

to the calling party a busy condition of t e called line in response'to the actuation of said ringing key by the transmission of a signal from .saidtdevice, means controlled by the called party for rendering said, link circuit con.-

tinuous, and means independent of said repeating. coil for restoring said switching mechanism.

13. A telephone iug telephone lines extending from substations to a'central station, normally electrically discontinuous link-circuits at the latter station for uniting said. lines, repeating coils included in said link-circuits for inductively uniting parts thereof, switching mechanism controlled from a calling station for connecting. calling and called lines to opposite ends respectively-of one of said link-circuits, means rendered operable uponv completion of the connection to the called exchange system compris party for rendering the included- -link circuit continuous for conversational purposes, a ringing key at the calling substation, means for indicatin to the calling party a busy condition o 'the' called line controlled by said ringing'key, and means independent of said repeating coil for restoring the said switching mechanism. 14. A telephone exchange system comprising telephone lines extending from substations to a central station; normally electrically discontinuous link-cirbuits at the latter dering the included link-circuit continuous for conversational purposesafter connection made to a called line, means for connecting said interrupter to the calling end of said link-circuit to supply current impulses to the calling station as an indication that the desired line is busy, responsive to a manually actuated switch at the callin phone, and a relay connected in circuit with the winding of said repeating coil and adapted upon response of the called subscriber to control the release of said switching. mechanism.

15. A telephone exchange system comprising telephone lines extending fro substations to a central station, norinall electrically discontinuous link-circuits t the latter station for uniting said lines, epeating coils included in said link-circuit for inductively uniting parts thereof, lswitching mechanism controlled from a callin station for connecting calling and calle lines to opposite ends respectively-of one of said link-circuits, a circuitinterriipter, a re tele- "9J2". i 17. A telephone system COIIIPIISIIIg tel'elay for controlling the continuity of the included link-circuit, means controlled by the associated switching mechanism and said station to control the release of said switch-' ing mechanism. V

16. An automatic telephone system including subscribers lines, and a connector for connecting directly with called lines comprising a repeating coil for transmitting voice currents between connected telephones, and a differential relay operable from connected telephones for restoring said connecphone lines, a connector for connecting d1- rectly with-called lines, including a repeat-.

ing coil for transmitting voice currents between connected telephones, a differential relay for restoring purposes connected with said repeating coil, said relay being operable from connected stations to restore said connector to normal, and a second relay actuated by current over a called line to connect said differential? relay with the calling telephone.

18. A telephone system including telephone lines, a connector for connectmg directly with called lines, a pair of bridged relay coils for said connector, operable responsivc to current over the calling line to adjust said connector to connection with the called line, an inductive device having four windings arranged in pairs for transmitting voice currents between connected telephones,

. a differential relay having a pair of wind-' in connected respectively to intermediate points of said pairs of windings, a relay ada ted to be operated when the called subscri er answers, and switchin mechanism controlled by said. relay for isconnecting said bridged relay coils from the calling line and orgeratively connecting said difierential relay therewith.

19. ii teleph ne system including tele: phone lines, a connector for connecting- 'directly with called lines,l i'r i y ing a repeating coil for transmitting voice currents between connected telephones, a, dilierential relay for said connector for release purposes, means for interchangeably "connectingthe answering end of said connector with difierent calling lines, and a second relay for said connector for operation when the called subscriber answers the call, adapted to connect said= repeating coil and saiddifi'erential relay with a calling line in connection with said connector.

20. A telephone system including telephone lines, a connector for connecting directly with called lines, selectors adapted to be operated from calling telephone lines to interchangeably connect said calling lines with said connector, a repeating coil for said connector for transmitting voice currents between connected telephones, a. differential release relay for said connector, a trunk release circuit controlled by said relay and a second relayfor said connector for operation to connect said release relay with the calling, telephone line. a

21. A telephone system including telephone lines, a connector for connecting directly with called lines, selectors for operation responsive to current transmitted from calling substations to interchangeably connect calling lines with said connector, a pair of bridged relays for operation res onsive to curr transmitted over callin 'nes to adjust said connector to connection' with called lines, a repeating coil for said connector for transmitting voice currents between connected telephones, a differential release relay for said connector, and an auxiliary relay for said connector for operation to disconnect said bridged relays from the calling line and operatively connect said release relay therewith.

22. A telephone system including a call-, ing subscribers line and. a called subscribers line, a connector switch for directly conmeeting with said called line provided with a repeating coilfor transmitting voice currents between said lines, a selector switch for connecting said calling line to said connector switch, means controlled by the called subscriber for connecting the said repeating coil to the calling subscribers line, a double wound battery supply relay connected to* said repeating coil, a trunk release circuit extending between said selector and connector switches, and means undercontrol of said callingsubscriber for operating said relay" whereby said trunk release circuit is rendered effective. a

23. A telephone system including a calling subscribe'rs line and a called subscribers line, a connector switch for directly connecting with said called line, a repeating coil individual to said connector switch for 24. A telephone system including a calling subscribers line and a called subscribers line, a connector switch for directly connectbetween said lines, a selector switch for con-' necting said calling line to said connector, switch, means controlled by the called sub-' controlled b ing with said called line provided with a repeating coil for transmitting voice currents scriber for connecting the said repeating coil to the calling subscribers line, a double ;wound batter supply relay connected to said repeating coi electromagnetic release mech anism' for each of said switches, and means one cf said subscribers for operating said relay whereby said electromagnetic release mechanism is operated to cause a restoration o fsaid switches.

25. A telephone system includinga calling siibscribers line and a .called subscribers line, a connector switchfor directly connecting with said called line, a normally inoperative repeating coil individual to said connectorswitch for transmitting voice currents between connected lines, a selector switch for connecting the said calling line to the said connector switch, a releas'ecircuit extending between said switches, substation controlled means for rendering said repeating coil operative, a battery supply relay for supplying talking current to the line of the calling subscriber, .and means controlled by said calling subscriber for operating said relay to effect said circuit thereby causing the restoration' of said selector switch to'nor al. v

26. A tale one system comprising calling and calle subscribers lines divided into groups, a selector'switch for extending calls from said callinglines'in the direction of said called lines, a connector switch for connecting directly to said called lines including a repeating coil for transmitting voice currents between connected lines, a release relay for restoring pur oses connected to said repeating coil, an means controlled over each of the connected lines for o erating said release relay torestore sai connector.

27. A telephone system including a callingsubscribers line and a called subscribers line, a connector switchfor directly connecting with said called line, a repeating coil 4 individual to said connector switch for transmitting voice currents between connected lines, a selector switch for connecting the said calling line to the said connector switch, a battery feed relay for suplying talking current to the said called ine, and means controlled by the called subscriber for operating said relay to bring about'a release of said connector switch.

. 28. A telephonesystem including a calling subscribers line and a called subscribers line, a connector switch for directly connecting with said called line provided with 'erating' bridge and for connecting .a-repeating coil for transmitting voice currents between the said subscribers lines, a selectorlswiteh controllable from said calling line for connecting with said connector switch, an operating bridge forsaid connecto'r switch 'for'controlling a selecting operation' the'reof, means controlled by the called subscriber for disconnecting said opsaid repeating coil to thecalling subscri ers line, adouble wound relay connected to the said called line, and means controlled by the called subscriber for operating said relay to cause a release operation of said connector" switch.

29. A telephone system including a calling subscribers line and a called subscribers line, a connector switch for directly eonbridge for said connector switch for control lingaii operation of said connector, a repeating coil for said connector switch, for

transmitting voice currents between connect ed lines, a selector switch for connecting the said calling line to the said connector switch, means for disconnecting said operating bridge and for. connecting said repeating coil tothe calling subscribers line, a battery feed relay for supplying talking current to the said calling subscribers line, and means controlled by said calling subscriber to operate said relay to bring about a release of said selector switch. a

30. A telephone system including a calling subscribers line and. a called subscribers line, a connectorswitch for directly connecting with said called line provided with a repeating coil for transmitting voice currents between the said subscribers lines, a selector switch controllable from said calling line for cormecting with said connector switch, an operating bridge for said connector switch for controlling a selecting operation thereof,'means controlled by the called subscriber for disconnecting said operating bridge and for connectin said re peating coil'to the calling s uhscri rs line, a double wound current supply relay for supplying one of said lines with talking current, and means controlled at the substation of said last line for operating said relay to disconnect said subscribers lines.

31. A telephone system including a calling subscribers line and a called subscribers line, a connector switch having selecting motion in two intersecting planes for directly necting with said called line, an operating connecting with said called lineand pro-' vided with a repeating coil for transmitting voice currents between the said subscribers lines, a selector switch having motions in two intersecting planes controllable from said calling line for connecting with said connector switch, an operating bridge for said connector switch for controlling a selecting operation thereof, means controlled lay said operating br dge and for. connecting .said repeating coil to the calling subscribers line, a double wound current supply relay for supplying one of said lines with talking current, and means controlled at the substation of said last line for operating said reto disconnect said subscribers lines.

. 32. A telephone system including a calling subscribers line and a called subscribers line, al connector switch, for directly connecting with said called line provided with a repeating coil for transmitting voice currents between the said subscriberfs lines, a

selector switch controllable from said calling line for connecting switch, an operating nect'or switch for controlling a selecting operation thereof, means controlled by the' called subscriberior disconnecting said operating bridge and for connecting said repeating coil tothe calling subscribers l1ne,a

battery feed relay for supplying talking 1 current to the said calling line, release mechanism, for each of said switches, a release circuit for' said release mechanism and means controlled by the calling subscriber for operating said relay whereby the said circuit isclosed to cause a release operation of both of said switches.

33. A telephone system comprising sub scribers telephone lines divided into groups,

c m 0! this patent my be obtained to:

a selector switch with said connector bridge for said con-' be cent: each,

for extending calls from calling lines in the direction of called lines,- a connector switch for connecting directly as with called lines including a repeating coil for transmitting voice currents between connected tele'phonesfa' release relay directly controlled from each of the connected lines for restoring said connector.

34'. A telephone system including sub-' scribers telephone lines, a connector switch for directly connecting with one of said lines, a repeating coil individual to said connector for transmitting voice currents be- 45 tween a pair'of connected subscribers lines, a selector switch adapted to beoperated to connect with said connector switch, an oper-- ating bridge for said connector switch for controlling an operation. thereof after said 9 selector has connected to said connector, means controlled over said subscribers line for disconnecting said operating bridge and a for substituting said repeating coil to render the same effective to transmit the voice 5 currents, a battery supply relay for supplying talking current, and means controlled by said relay for releasing said selector.

' In witness whereof, I hereunto subscribe my name this 31st daFy of March,1906.'

i AL RED H. DYSON.

" Witnesses:

CAROLYN WEBER, T. H. FERGUSON.

s addressing the "0mm: .1 has.

Washington. D G."

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