US1705906A

US1705906A - Telephone system

Info

Publication number: US1705906A
Application number: US194033A
Authority: US
Inventors: Joseph W Dehn
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1927-05-25
Filing date: 1927-05-25
Publication date: 1929-03-19
Anticipated expiration: 1946-03-19

Description

March 19, 1929.

J. w. DEHN TELEPHONE SYSTEM lsxwets-shee'fA 1 Filed May 25, 1927' NSK l Imm.

/NVE/vroR JosfP/f M! Diff/v 5r A TOR/ver March 19, 1929. J, w, DEHN 705,906

TELEPHONE SYSTEM Filed May` 25, 1927 4 sheets-Sheet 2 *K* AMW-vf ii Il :n ibi-h HF @L "E N n A A L l l I l l March 19, 1929.- J, w. DEHN 1,705,906

' TELEPHONE SYSTEM Filed May 25, 192'/ 4 sheets-sheet 5 4 Sheets-Sheet 4 March 19, 1929. J.'w. DEHN TELEPHONE SYSTEM Filed May 25, 1927 mummx u 1S W|WEFTNHQHHHW fi.

than

Patented ,Mal 19, 17929.y i

uuirsnsraras Partnr Aoi'fricia..

` Josnrn W. DEHN, or BROOKLYN, NRW YORK, AAssieNoiIt To :BELL TELEPHONE LARO- RATORIEs, INCORPORATED, or NEW YORK, N. Y., A CORPORATION or NRW YORK.

TELEPHONE sYsTEM.

K'- l VApplication `filed. May 25,

In accordance-with one feature of this in# vention there is provided a tieline circuit yin which dialing impulses areV transmitted from one terminal station to the other through special dialing jack, so arranged that the dialing jack is connected, in response to the seizure thereof, to thel tie line before a bridge connection across the conductors of ythe tie line vis disconnected theretromto prevent false operations of the impulse relaysatthe other terminal station.

' In accordance with another feature ot this invention there is provided a system having a tie line circuit in which the wanted lines are selected through automatically operated switches, and wherein the selective impulses incoming over the tie lineare repeated to the automatic switches by a vhighly sensitive/repeating relay arrangement. This repeating relay arrangement is disconnected from' the tie line and the tie line connected through the v automatic switches' to the calledv subscriber ffor talking purposes when the called subscriber answers vthe call by removing his receiver from the hook.

rllie invention has been illustrated in the accompanying drawings in which Figs. l, 2 and 3, when arranged asillustrated in Figq,r

show the circuits of Ya tie lineV at one private branch exchange while Fig. 4; shows the circuits O this tie line at another private branch exchange. Referring to the drawings the circuits at station A, Figs. l, 2 and are so arranged that calls may be made from this station by'seizing the tie line T either manually through a jack 202v by means of a private branch exchange operators cord A'circuit shown partly at 203 or automatically from a private branch exchange subscriber through a. selector' shown in Figi. These circuits at station A are also arranged so that calls incoming over the tieline T may be completed to private branch exchange subscribers at this station automatically through the actuation of the connector shown in Fig. 3 and so arranged that these calls may be completed through the lighting ot a lamp! at jack 202 automatically, from operations of said conn nectar and the manual completion oi:

` this purpose.

1927. Serial rfa-194,033.' v

nection, to the wanted private branch eX- change subscriber through cord 203. The cirf cuits associated with the tie line at rstation B,

Fig. areso arranged that calls originating `from this station may be made'by seizing the tie line through jack 402 from a cord circuit partially shown at 403 and by transmitting selective impulses from a dial 405 which may be associated through an ordinary cord 407 and the dialing jack 406 with the tie line tor To illustrate the various features of .this invention as embodied in this type of tie line circuit, descriptions of the above calls will be made in the order mentioned.

Assuming that the private branch eX- change Voperator at station A has answered. a call from a private branch'ezrchange subscriber in the usual manner by means of the cord 203. The extension ofthe connectionV over tie line T may be 'initiated by the insertion ot plug 201 of this cordinto aclr 202.

Springs 206 of this jack arethereby closed to provide a circuit for the operation Ofrelay 205. The circuitfior this relay is obviousfand whenthis relay operates it closes a circuit for the operation of relay207. The circuit for relay 207 inav be traced from bat- `tery,vlowerwinding of relay 207, lower inner a circuit for the operation otrelay 209 as follows battery, winding oi2 relay 200, upper inner armature and front contact ot relay 207 to ground. Relay .209 in operating completes the connections torgthev tip and ring conductors of line T trom the battery and ground through the winding of relay 208'by way of the upper outer and the-lowerarmatures and front contacts of relay 207 andr the upper outer and lower outer armatures and iront contacts of relay 209. It'will benotedthen that, due to the operation otrelays "205, 207 andv 209, the tip and ringl conductors oit tie line Tai-e connected to the right-hand sides of condensers 210 and 211 and to battery and ground. respectively, whlefths other sides of the condenscrs are connected through the terminals of jack 202 and plug 2 1 to battery and ground in the cord circuit 203.

The operation ot' relay 205 also connects at its upper inalre-before-brealr Contact the sleeve conductor tor the selector of Fig. 1

to ground so as to maire the tie line busy to rlhe operation ot relay 209 the selector. closes an obvious circuit :tor the Voperation of relay 212 and this relay in operating closes a connection to ground for the sleeve circuit 0f jack 202 to malte busy and to light the supervisory lamp 218 oi cord 208 to indicate to the operator that thc tic line has been connected.

The battery and ground connections through the windings of relay 208`will now cause the operation ot relay 410 trom the tip conductors of line T through both windings vol' relay 410 in series, the lett hand armature and back contact of relay 411 to the ring conductor of line l. lclau 410 in operating closes a circuit for the lighting ot lamp 412 as follows: battery, armature and it'ront contact ot relay 410, lei-'t hand arn'iature and liront contact of relav 414, lamp 412 to ground. The lighting ol. lamp 412 indicates to the private branch exch operator at station B that a connection is desired over line T. y

In answering this call this operator will insert plug 415 ot cord 408 into jack 402. This operation closes a connection to grounl at contacts 416 oic jack 402 for the energizing Circuit lier relay 417. Relay 417 in operating closes a circuit for the operation ol' relay 414 as follows: battery, armature and front c0ntact of relay 410, outer right hand armature and front contact of relay 417,'windingv of relay 414 to ground. Relay 414 in operating opens the circuit for lamp 412 and bridges the repeating coil 420 across the tip and ring conductors to jaclr 402 to cause the peration ot the supervisory relay 421 from the battery and `ground supplied through the windings of rela-y 423 in cord 408 and thus prevent the lamp 422 from lighting on the actuation of relay 417 which as noted closes the sleeve circuit. The cord circuit 403 has only been shown in diagrammatic torni as it 'forms no part ot thc invention in this application. For a more complete showing` of suitable cord circuits for use in this connection reference may be had to the cord circuits shown in the copending application ot W l. Striclrler, tiled May 27 19279 Serial No. 194,576. rlhe operation of relay 417 also short circuits the lett hand high resistance windingof relay 410 at its lett hand armature and contact and thus reduces the resistance of the circuit through relay 208 vto permit suiicient current to flow through this relay to cause it to operate. Relay 208 in operating closes an obvious circuit lor the operation of relay 215 and this relay in operating closes an obvious holding circuit for relay 209 and also by operating its .extinguished to indicate to the private branch exchange operator at this station that the y private branch exchange operator atstation ll has answered the call. As a connection is now completed through cord 203, tie line T and c rd 408, the operator at station A will now give the wanted'suhscribers nuinberto the operator at station B. rlfhis operator may then complet-e the connection inthe usual manner to the wanted subscribers .line and aiter this subscriber hasl been rung `and answered the call, conversation between the calling and the called subscribers may begin, Y n ln releasing this connection Yfrom station B plug 415 is removed from jack 402 and relay 417 releases. The release of this relay reinserts the high resistance winding ot relay 410 in the circuit tor relay 208 which is thereby released and this .relay in releasing causes the release of relay 215 which removes the bridge through the retardation coilA 217` 'from the tip and ring terminals of jack 202 to cause the supervisory relay 218 t0 be released and the supervisory vlamp 218'to'be lighted to indicate to the operator at A that a release of the connection is desired. This operator will then remove plug 201 from jack 202 to cause the release of relay 205 which in turn causes the release of relays 207 209 and 212. The release ot relay 20.9 `causes the release of relay 410 and this relay in releasing causes the release ot relay 414 lso that the circuits at the two stations are now returned to normal condition.

It the release had been initiated from station A. by the operator at this station removing plug; 201 from jaclr 202., relays 205` and 207 would have been released. Relay 207 in releasing reverses the connections from bat# tery and ground through the windings ot' relay 208 :tor the line T, thus causing the release ot relay 410. Relay 410 in releasing releases relay 414 and this relay in releas` ing removes the bridge through the retardation coil 420 for the tip and ring terminals or' jack 402 and thus causes the release oit supervisory relay 421 and the lighting ot' lamp 422 over the sleeve circuit. The lighting` ot this lamp indicates to the operator at station l that release of the connection is desired, whereupon this operator removes plug 415 from jack 402 to cause the release of relay 417. This rela-y in releasing reinserts-the high resistance winding o'lz relay 410 in the circuit for relay 208which then releases and causes the release of relay 215. Relay 215 in releasing opens the circuit for relay 209. This relay in releasing disconnect-s the tie line' T from the circuits at station A, and causes iio i sleeve circuit for the selector, Fig. 1'.

If a vsubscriber at station A desires toV make ya connection to a distant station` by automatically selecting a" tie, line vthis iconnection may be made throughthe selector shownv in Fig. 1. The subscriberwmay'seize anidle selector, such asthe one shown inv Fig.'1, through a usual line linder (not shown) and thereby cause the operation of relay 100over Y i p to the desired level or vgroup of tie line terminals, relay 107 releases but relay 111 rea circuit closed through the subscriber@ loop over to the tip and `ring conductors of this selector. This circuit may be traced from battery, right hand winding of relay. 100, inner lower armature and back contact o'frelay 101 and ring .conductor `through the "subscribers loop back through the tip conductor,

rrso

upper armaturel and back contact of'relay A101, kleft hand winding of relay 100, 11th y step rotary off-normal kcontact-s 102, secondary winding of repeating coil 103 to ground. The secondary winding of this coil is con-y nected .to a tone'y source at V104. 1When this connectionis completed a tone will be transmitted tothe calling subscriberstelephone set'indicating that selectorlhas been seized and' that dialing fora tie 'line to `thedesired private branch exchange may begin.

The operation of `relay.100l closes obvious circuit for. the operationof slow-td release relay 105 and this relay closesa connection from ground at its inner armature and front contact y'for the sleeve circuit to the line finder to hold the' connect-ion in the 'of-levels and hunt` for the terminals of an lidle tie line onuthat level the calling subscriber may now operate his dialto actuate f the selector to select the desired level in which terminals of tie lines leading to the desired private branch exchangeare located. The' der these circumstances but the ground on selector itself forms no part' of this linvention and it is therefore considered that this explanation will bey sutlicient to'understand the features of the invention as hereinafter described. I

Relay 100 will follow the interruptions by the dial of the circuit therefor and operate the vertical magnet v106 over a circuit that may be traced from battery winding of the vertical magnet 106, winding ofslowrorelease relay 107, outer right hand armature and front contact of relay 105, armature and back contact' of relayv 100 to ground at the lower armatureandbacl contact of relay 101. Relays 105y and 107 will remainoperated duringthe'puls'ing operations.V The vertical magnet 105fsteps the brushes108lof` the selector to the desiredr level, and onthe tirst vertical step to ,advanceA the brushes the vertical olinormal 'springs 109 close connection to prepare the circuits for the 'operation of the release magnet 110v and the operation ofthe rotary magnet 114`asl'iereinafter described. rllhe immediate result from the operation of these off-normal'contacts is the closing of a circuit for the operation'o'f re- Vlay 1171 as follows: battery,gwinding of re- Y ylay 111, lower springs ofcontacts109, armature and front contact of'relay'v 107, inner right lhand ,armature and front contact of relay 1,05 to ground. When the dialing iscompleted and the brushes 108 have arrived mains inloclredposition under control of .-a circuit .completed through the armature and back contact of the rotary magnet y114.

Thisholding circuit may be traced from batf' tery, winding of relay 111, lower springs of the vertical olf-normal contacts 109, armature and back contactsof rotary magnet 114,

outer right hand armaturev and front con The firsty operationof rotarymagnet 114 Y steps the brushes to thefirst set ofterminals V- in the selected level and on the operation of rotary magnet 114 relay V111 will release ifV the lirst line in this level is idle. However,

if the first line is busy the sleeve terminal y of the brushes 108 is connected to ground.

.This ground 'shunts the winding of relay 101 which now is'in a series circuit with the relay 111 extending to the ground at the inner yarmature and front contact of relay 105 vthrough the middle Vlower farmaturewand back contact ofy relay'V 101. Relay 101 'is consequently prevented from operating un'- the sleeve terminal' Vcauses jther reoperation of relayf11-1 over a "circuit as follows: battery, winding of relay'111, lower springs of vertical olf-normal contacts 109, armature and hack contact. of rotary magnet 114, lower normally closed springs of 11th stepv rotary contacts 102, middle lower armature and back contact of relay 101, sleeve terminall of the brushes 108 to the ground on the sleeve of the connected line. Such a ground may be traced, forr example, through Fig.V 2 to the outer left hand armature and front contacts of'relay -212 or upper inner make-before- 'brealr contacts of relay 205 of tie line '1l if Vit is busy. Onv the operationof relay 101 rotary lmagnet 114 isV again energized and relay 101 will operatein the series circuit through relay 111 but relay 111 will not' op- ,these operationswill continue untily an idle tie hneis'found. When such a line is reached ing subscriber-s line and the line iinder through to the brushes 108 at its upper, lower inner and lowerV middle armatures and their respective front contacts.

On the completion of these connections a circuit is completed 'for the operation of relay 207 from battery, through the lower winding oi relay 207, ring terminal of brushes 108, lower inner armature and front contact of relay 101, ring conductor through the subscribers loop back to the tip conductor, upper armature and back contact or relay 101, tipterminal of brushes 108, the upper winding of relay 207 to ground. Relay 207 in operating` closes the circuit for relay 209 andV this relay in operating closes the circuit `for thevoperation of relay 212 as hereinbeiiore described. Relay 212 in operating connectsground to the sleeve circuit to make the terminals of line T busy to other selectors and for holding relay 101 operated after relay 105 has released as it will after relay 100 is disconnected from the subscribers loop by the operation of relay 101. The operation of relay 207 reverses the battery and ground connections through the windings of relay 208, for the tip and ring conductors of line T to cause the operation of relay 410. This relay in operating causes as hereinbefore mentioned the lighting oit lamp 422 and when the operator at station B answers this call by inserting plug 415 into jack 402, circuit changes take place to extend the connection 'from this operator to the calling subscriber at station A in the same manner as hereinbei'ore described .in relation to the establishing of a connection between the operator at A and thev operator at B except that connection in this case now extends tl'irough the selector shown in Fig. 1 to the calling subscriber.

V hen the `calling subscriber at station .A releases, relay 20Ty releases to reverse the battery and ground connections through relay 408 and relay 4110 releases and as hereinbetore described the operator at B is signaled to break down the connection. The operator at B now removes plug 415 from ack 402 causing the release of relay 417 which as hereinbefore described causes the release'otl relay 208 and relay 215. yRelay 215 causes lthe release of relay 209 and this relay causes the release ct relay 212 which thereby removes the groundV on the'sleeve to the selector of Fig. 1. Relay 101 is therebyv released and closes a circuit for` the release magnet 110 as follows: battery, upper springsof olii-normal contacts 109, outer right hand armature and back contactof relay 105, armature and back contact of relay 100, lower outer armature and back contact of relay 101 to, ground. The selector circuits are thereby restored Vto nor- .mal condition and t-he line finder isreleased as is well known inthe art bythe removal of the ground connection `from the sleeveand the release of relay 101.

If a call originates at station B the first action on the part of the private branch eX- change operator at this station would be to insert plug 415 ol cord 403 into jack 402. Relay 417 is thereby operated overan obvious circuit and the operation oi thisv relay short circuits the high resistance winding of relay 410 and also causesthe supervisory lamp 422 to be lighted. It should now be noted that on the establishing of this short circuit for the high resistance winding of relay 410 the

pulse repeating relays

220 and 221 will operate over a circuit as follows battery, through the middle windings of relays 221- and 220 in series, inner left hand armature and back con-` tact of relay 223, lower outer armature and back contact of relay 209 over the ring conductor of line T, left hand armature and back Contact of relay 411, left hand armature and front contact of relay 417 through the left hand winding of relay 410, tip conductor of line T,y Lipper outer armature and back contact of relay209, outer right hand armature and back contact of relay 223, right hand windings of

relays

220 and 221 in series to ground. It should be mentioned 'here that relay 221 may or may not be normally oper ated over the circuit established throughthe two windings of relay 410, that is, it is immaterial whether or not this relay operates under these conditions, while relay 220 is ad* justed so that it will not operate from the current normally flowing over theV line through the two windings ofrelay 410. The immediate result of the operation of

relays

220 and 221 will be to establish a connection to ground through the outer armatures and front contacts over thelead 225 tor'theoperation of relay 300.` .The circuit forrthis relay may be traced from battery, through the left hand winding of relay 300, outer left hand make-before-break contacts V of relay 301, lead 225, armatures and iront contacts of

relays

221 and 220 in seriesrtfo ground. Relay- 300 in operating closes an obvious cire cuit for the operation of relay 302. Relay 302 in operating closes a circuit forthe operation of relay 212 as follows: battery, winding` of relay 212,` upper inner armature and back contact of relay 20,9, lead 226 to ground at the outer left hand armature and front c0ntact of rela-y 302. Relay 212 in operating ai upper armature and back Contact of relay 209,

conductor 225 to ground at the' outer lett hand armature and back contact ot relay 302. The

circuit for relay 221 aids the relay in releasing during the pulsing while the circuit tor relay 220 acts as holding circuit for this relay during the pulsing. This combination or pulsing relays therefore will be particularly sensitive todialing impulses.

The operation of relay 302 also closes the circuit for the operation of relayr 304 and ver-V tical magnet 305 as follows: battery7 winding oi vertical inagnet305, winding ot relay 304, normally closed lower vertical off-normal contacts 300, inner arniature and front contact oi" relay 302 to the armature and-back contact ot relay 300. The connector circuit in Fig. 3 is now ready for the receptionol dialing impulses troni station l5. y

To dial the wanted subscriber the operator at station B will now insert in' dialing ack 40GA a plugsuch as 420 oiy any 'available cord such as 407 having a dial such as 405 associated therewith through the operation oit the dial key 425. This cord has been shown only y in diagramn'iatic vtorni as itiorins nofpart oft this invention. 'For ar` more complete showing ot'cord .circuits suitable for use in this connection reference may behad to the cort circuits shown in the copending application oil/V. B. Stri'ckler, filed May 27,1927, Serial No. 194,570. However, in oider to dial, a connection must now be establishedover` the tip and ring Aconductors of line T'through the tip and ring conductors of the jack 40G and plug 420 throughthe pulsing contacts oi" diall 40:3. This connection must be closed be- 'lic'rethe bridge through the lett hand Winding ot relay 410 is removed from across the tip and ringconductors of the line in order to maintain

relays

220 and 221 operated and thus prevent any false impulsesbeingtransinitted to the connectorin Fig. 3. To this end on the insertion of vplug 42S` in ack 406 a cirf cuit will be completed` from ground in the cord, the winding o1 relay .424, sleeve terminals of plug425'andjacl; 406, the. upper outer closed contacts ot jack 40S, winding of relay 427 to battery. 4Relay 42,7 is slow to operata while relay 424 is quick` to operate, so that they battery and ground connected (when the dial key 425 is operated) through the windings oic relay 428 andthe armatures and backy contacts of relay 424 `(beforek this vrelay is operated), to the tipfand ring terminals of Viii-ade contacts oi plug 426 and jack 406,.shall not cause the operation of relay 430 through the voperated armatures of relay 427. When relay 427 now voperates a circuit will be completed `tor relay 430 through` the above mentioned circuit through the pulsing contacts ot' dial 405.

lt should be understood that usually the. operator will actuate the `talking key 425 be-.

tore. .she inserts/plug 426 into jack 400. Should' she, however, neglect to doso it may be operated after the connection is made with the dial-jack.v ln this case it should loe noted that thebridge through the retardation coil 431 is established .across the tip and ring conductors on the operation of relay 424. This vbridge will therefore under such circum-v stances complete the circuit tor the operation otrelay 430 and when tlie'dialing keyis operatedv this bridge'will be in parallel with the bridge through the dialing contacts. With fsa p the dialing key operated the circuitfor rey lay 430 maybe tracedv from battery and ground through the windings oli relays 221 and 220, tip and ring conductors kot line T as hereinljiefore described through a loop extend ing troni the tip conductor ot the line through the upper outer armature and liront contact of relay 427, tip terminals of jackf406 and plug 420 upper outer made contacts of key425, .pulsing contacts of'dial .405, lower outer t' key 425, ring terminals ot plug 425 and jack 400, winding ot' relay 430 through tlielower armature and front conot relay v427 back to thering conductor ot' line T.l Relay 430m operating closes an oliviouscircuit 'for relay 411 whichA in operating closes a locking circuit 'for itself under control lof al connection to ground lthrough the vupper inner armature and contact of relay 427. The operation or" relay 411r causes a holding circuit to bey established through its outer right hand armature Vand ti'ont'contact for relay 417 to maintain this relay operated during` dialing in case the operator 'inadincrtentlyA removes plugv 415 from jack 402.v This relay 411 alsoopens the bridge'through the right hand winding oic relay 410 across the tip and ring conductors and short circuitsthe winding of relay 430l softha't the vpulsing' circuitwill not vbe eX- tended Atree of lall encumbrances trom the pulsing contacts ot dial 405 throughthe two windings ot relays 220 and 221.

llO

The operator may now dial thenuinber of the desired subscriber at the distant exchange.V

At the rotation ot the dial from normal the olli-normal contacts thereof will close a ciry cuit for the operation of 432 and thisrelay in voperating will open at its niake-betore break contacts theco'nnections for the bridge throughretardation coil V431 across the tip and ring conductors `and connect this bridge to battery andA groundthrough the windings of relay 433 which now operates and provides a. `locking circuit for relay 432, so the bridge will be permanently removed trom the dialing circuit. fit each interruption oli the pulsing contacts oi' dial 405, relay 221 will release thus opening the circuit tor relay 300 which will thus release in response to each interruption of the dial contact. Relay 300 in releasing causes the above mentioned circuit for relay 30e and vertical magnet 305. to closed and the magnet 305 will follow the dial pulses while relay 304 which is slow to release will remain operated during the puls-v ing. rlhe vertical magnet will step the brushes 310 of the connector to the desired level in which the terminals of the desired line are located. As the connector' itseli" iiorins no partv of this invention no detail description will be made thereof, except such operations thereo't that may serve to clarify the description of the invention. @n the lirst step of the brushes the vertical oli-normal contacts 306 will be operated to prepare a circuit for the release magnet 311 and 'transn r'er the pulsing circuit for the magnet 305 and relay 304i through 'the armature and 'iront contacts o'r relay 304 and the lower closed springs et the vertical olif-normal contacts 300; -When the impulses 'from dial L105 cease, relay 300 will remain operated and relay 3041- release thus transferring the pulsing circuit from the certical magnet 305 to the rotary magnet 313.

The circuit :tor the rotary magnet 313 may be traced :troni battery through the Winding of this magnet, second inner armature and bach contact oit relay 303, upper middle armature and back Contact o1' relay 315, Winding of relay 316, armature and back Contact oit relay 3011, lower closed springs ot vertical oil-normal closed contacts 306, inner le't't hand ari'naturc and haelt contact of relay 302 to the armature and baci; contact of relay 300 to ground. Relay 316 and rotary magnet 313 are operated in this circuit on the next series of impulses from dial 105. 'lhat is, relay 300 on. releasing and operating causes the operation and release oi the rotary magnet 313 which as stated is in a series circuit with relay 316, Relay 316 operates on the lirst im* pulse and being slow to release remains operated. during the succeeding impulses. T he rotary magnet steps lthc brushes 310 over. the

terminals oil" the selected level to the terminals oit the wanted line. lelay 316 in operating prepares a busy test circuit by closing a connection through its outer lett-hand armature and iront contact tor the sleeve terminal oli the connector. lt should be 4noted that the pulsing circuit ttor rotary magnet 313 will now extend through the inner' le'lt hand armature and nt contact ott relay 316.

lf the wanted line is busy a ground will be present on the sleeve terminal oi the wanted line and in this case relay 30.1 will operate over a circuit as follows: `from battery, through the right hand winding ot relay 301,

lower male-bcforebreal contacts, oit relay 313,` resistance 319, outer left hand armature and front contact of relay 316 to the sleeve brush and terminal of the selected line toture and iront contact oi' relay 301 to the conductor 323 through condenser 324C by way oi the upper make-before-'brealr contacts of rel lay 318. This tone is transmittedV through condenser 228 to the tip conductor of the line T and from there to the operators telephone set in cord l0? at station B. This tone remains on the line until the operator at station B has ren'loved her plug.

lt the wanted line is idle, battery connec-` tion will be encountered on the sleeve of the wanted line and thus relay 301 will be prevented from operating through the above mentioned circuit prepared by the operation or" relay 316.` lllhen relay 316releases aftery the last impulse relay 315 will operate over a circuit 'from battery, through the sleeve circuit oi' the connected line and sleeve brush oit the connector, the left hand armature and back contact of relay 316, upper winding of relay 315, third armature and bach Contact ol' relay 301 to ground at'the middle armature and liront contact of relay 302,

Relay ico 315 in operating closes a locking circuit forVV itself through its lower winding and lower inner armature and front contact to ground at the outerlelt hand armature and liront Y contact ,of relay 302. 'lhis relay also places a ground on the sleeve terminal oit' the wanted line tor the operation of the usual cut-olf re-` lay. lhis connection is established through the second lower armature and liront Contact oi relay 315 to ground at the outer left hand armature and 'ront'contact ot relay 302.

A circuit will also be closed by the operation of relay 315 lor ringing o the Wanted subscribed. The circuit from the ringing source, 'which may kbe connected at' the Vpoint 330, will extend through the upper armature and back contact of relay 313, upper outer armature and iront contact of relay '315, the

tip conductor and the bell of the wanted subv scriberls set to the ring conductor, lower armature and front conact of relay 315, lower nai re and bach contact and winding of relay 313, back to the ringing source con-l nected at point 330. T he ringing current induces a tone through the condenser 324V to the rip conducter bach to the calling ope 'ator at station l indicating to her that the Wanted subscribers bell is being rung.v Thistone is introduced frein the'u'pper winding of relay 318 to the lower winding ofthisrelay and finds apath through the lett hand ywindingof relay 301 to the condenser 324. Relay 3118 is so designed as not to operate on the ringing` current but when th eV receiver is removed froin lthe -hookby a called subscriber, the' .direct current which is superimposed-on the .ringingcurrent will operate relay 318 and this relay in operating establishes a locking 'cir-z cuit for itselffroin battery, through-lts lower winding, lowei` inner armature andlfront contact to ground at the lett hand armature'and front contact oit relay 302.` Relay 318 in operating` cuts oli the connection frein the ringing source and closes a 'talking circuit through .te the calling subscriber on the left hand side of the condenser-e331 and 324 through the upper arinature and lower outer armature and front contact of .relay'318, upper and lower outerarmatures and front contacts'of relay f 315 to the connected subscriber-sline.`

When the talking connection'is completed' relay 301 operates through both windingsy overthe called subscribers loop. This vcircuit inay be traced from battery',fthroughvv the right hand windingfof relay 301, lower/outer ner armature and front contact of relay 318, to ground at the outer left hand armature and Y front Contact of relay 302. lTalking battery is now therefore provided Vtor lthe called sub-l scribers line andthe operation of relay 301 causes the battery .tor 'the operator at station B to be reversed. That is, battery will vnow be connected through lett hand winding of relay tact of relay 301, upper 'inner armature and front contact of relay 315, to the tip conduc-` tor 323, while ground will be 'connected through the right hand winding oi relay 300,' second outer armature fand front contactl'of relay 301, second outer lower armature and rontcontact of relay ductor 225. f

It will be noted'that'the reversal of battery and ground connections i'or the tip and ring conductors causes the voperation of relay 223 315 to the ring'conover a circuit as follows: battery, through thev winding of relay 300, to the tip conductor 323 as hereinbefore described, inner right hand armature and back contact of relay 223, wind ing of relay 223 to ground at the make-beforebreak contacts'of relay 212. Relay 223 oper-- ates and closes a locking circuit for itself directly to battery under control of the contacts of relay 312 and opens the original energizing circuit. Relay 223 in operatingV disconnects relays 220 and 221 frein the tip and ring "conductors of line T and connects the. tip and ring conductorsv 323 and 225 to the tip and seen that .the repeating

relays

220 and 221 will ,be disconnected 'from .the Atal-king `c'onnection as soonfas thewanted subscriber has vansweredl'the'call.v In order tocoinplete this .talking circuit fromv battery and groundfat. relay'300 to the operator at station Bithe operator at this station will now reinove plug' 426`fr01n dialing jack 406 and thus release re# lays 427 and 411 to reconnect relay 410.acro ss -the tip and ring conductor offline T and con-j nect there conductors-through condensers435 and 436. to the calling operator. When this cause the operationof relay 414 andthis relay in turn vconnects .the retardation coil-420 ring conductors of line T. Thus'it vwill .be

s0V Y transfer is coinpleted relay 410v will operate to y across the tip and ring conductors to cause the operation o f `the supervisory relay 421 and the extinguishing of lamp 422 to indicate to the operatorat this station that the ftallin 0. f3 connection hasbeen completed. f

Y It the callod'sub'scriber releases the connection relay 301 will .be released.I Relay 301 in,

releasing reverses the battery and ground connectionsliron'i relay 300 to the line andv thus causes the release o-rrelay410. VRelay '410111 releasing causes the release of relay 414 and this causes Ythe lighting ot ,lamp 422 to indicate to the operator at this station that inove plug 415,-fro1'n-jack 402 to cause the `re-' .y lease vorelay 41.7*t0 reinsert the high resistthroughv the vertical oit-normal'contacts .306

and thus return the connector switch to n0rdisconnection isfdesired. She will then ref mal/position. vRelays 315and 318 are also rol leased by the release of relay 302. 300, outer left hand armature and frontcon- 1 Tf a connection is desired from .station -B to the operator at station A the operator atB. V`will proceed in the saine inanner as when` a subscriberatstation is selected automaticallyeXcept that the Zero is dialed. Iny this case the connector of Fig.l3 will b-e advanced to the zero level.r4 In thisposition a conne'ction will be closed to ground through theoprverationof the contactsy 334. This connection closes a-"circuit'over lead 335 for 'the operation of relay 230. Relay 230 in operating closes an obvious vcircuit for lighting lainp 2351 associated with jack 202 to indicate to the operatorfat station 'A that aconnection is desired over this line vrRelay 230 in `operatingcloses an obvious connection for the operation of reand back contact of relay 205. The operator at station A answers this call by inserting plug 201 in jack 202 and the operation ot relay 205 under these circumstances opens this circuit for relay 230, whilerelay 209 is held operated by the operation ot' relay 207 as hereinbefore describe-d.

The operation ot' the circuits from this point are identical with the operations when a connection is extended from the op-erator at lstation Ato the operator at station B.

It should be understood that the particular arrangements of circuits shown are merely 'illustrative ot one application or' the invention and that it is capable ot' being applied to various other tie line, arrangements without departing from the spirit thereof.

lWhat is claimed is:

l. In a telephone system, a line connecting two stations, impulse transmitting means at one station and impulse responsive means at the otherV station, relays at saidsecondstation for repeating impulses incoming over the.

line to said impulse responsive means, and means responsive to the irst repeated impulse ilor changing the character of response oi said repeating relays to succeeding incoming impulses so that one oit said repeating relays only repeats said succeeding impulses.

2. In a telephone system, impulse transmitting means, two relays having each a iirst fand a second winding associated with said two stations, impulse transmitting means at one station, 'a connector at the other station, two relays at said other station for repeating impulses incoming from the first stationV to said connector, means responsive to the actuation of said impulse iepeatiiig relays by the first impulse incoming thereto tor seizing said connector, and means responsive tothe seizure of said connector for locking one of said repeating relays in actuated position and causing the other of said repeating relays to independently respond to succeeding `impulses andaiepeatthe same` to the connector.

4. In a. telephonesy'stem, a line, a jack, a cord` circuit, a bridge connection` across the.

.i conductors of said line, and means responsive to the connection` of theV cord to the jackfor establishing a second bridge connection;-

acrossfthe conductors of said line and then re` moving the iirst mentioned-bridge connection.

5., .In atelephone system, a lineterminating in a jack, another jack, a cord circuit, a bridge connection across the conductors of said line,.v

and means responsive totheconnection of. said cord circuitwith saidv second Jack for establishing a bridge` through :the cord cir cuit'and the associated. jack across the conductors of said line, tor disconnectingI the.-

hrst mentioned jack from the line.l and for thereafter openingthe iirst mentioned bridge. 6. lIn a telephonesystem, a line, a jack, a

cord c' icuit, a dial insaid cord circuit, means .y

tor,establishing a bridge circuit through the impulse contacts of saidV dial across the vcony ductors oi said cordz, a bridge connection across the condnctors'o'f said line, means re-V sponsive when the bridge .through the dialis established and-the `cord is connected .withy said jack for establishing. a connection.v be-,v

tween the conductors of said linethioughsaid bridge in the cord. and through said jack and` lor thereafter openingtlie bridge connection V normally established across. the conductors, ol said line.

7. In a telephonek system a line, impulse transmitting means at one endffot said line,

relays connectedA tothe other end of said line responsive to, impulses from said ytransmit-1v tingrmeans for Vrepeating thesame, subscribers lines, a connector responsive to im-` pulses repeated, byrsaid relays tor selecting. a

corresponding subscribers line and connect ing it with the line conductorsf said con. nector, a relay connected to one of theline coilductors ot, said4 connectonineans for operating said relay in responseA to the seizure.,

of the connected subscribers line bythe subscriber tliereof, means controlled by theactun ation ot said relay for disconnecting. the im-l 1 pulse repeating relays frointheline, oifconnecting the line tothe connectedsubscribers line throughthe conductors ot the connector and for disconnecting the relay itseltfrom its connection with one of the lineconductors of the connecton Y In witness whereoig Ilhereunto subscribe my name this 18th day ot-,M-ay, A'. D.l927,.

Josnrn W. nini-N.4 c

ice