US2327201A - Telephone system - Google Patents

Description

Aug- 17, 1943. A. s." lvxmrnxsgA TELEPHONE SYSTEM Filed July 2, 1942 9 sheets-sheet i Aug. 17, 1943.` A. s. MAR-rms 2,327,201

` TELEPHONE SYSTEM Filed July A22, 1942 Sheets-Sheet 2 /NVENTOR A -By- A. 5. MART/NS ii if." 'l' Arron/VEP Aug. 17, 1943. A.s. MARTlNs 2,327,201

TELEPHONE SYSTEM Filed July 22, 1942 9 Sheets-Sheet 5 HRGINL /NVENroR By AS. MART/NS g ATTORNEY U8 17, 1943- ,A. s. MARTlNs 2,327,201

' I TELEPHONE SYSTEM Filed Ju 1y 22, 1942 s sheets-sheet 4 /NvENroR A. S. MA R T/NS ATTORNEY 9 Sheets-Sheet 5 m. .QQ

A. s. MAR'lNs TELEPHONE SYSTEM Filed Jul'y 22, 1942 /Nl/Nrof? A. 5. MA R T/NS er K y AT rom/EV Aug. 17, 1943.

Aug. 17, 1943. A. s. MARTINS 2,327,201

TELEPHONE SYSTEM Filed July 22, 1942 9 Sheets-Sheet 6 Ii n ATTORNEY Aug. 17, 1943.

A. s. MARTINS TELEPHONE SYSTEM Filed July .22, 1942 9 Sheets-Sheet 7 N .um

ATTORNEV Aug. 17, 1943. A. s. MARTlNs 2,327,201

TELEPHONE SYSTEM Filed July 22, 1942 9 sheets-sheet a /N f E RME DIA TE GROUP j ma /NVENroR A. S. MART/N5 i A7' TORNEV Aug. 17, 1943. A. s. MARTlNs TELEPHONE SYSTEM Filed July 22, 1942 9 Sheets-Sheet 9' /NVN To@ A. 5. MA R T/NS A7' TORNE Y E Patented Aug. 1.7, 1943 alfine ze f 'chen-ne notify the operator that a diiierent condition has been encountered. rIhis might be terined a syncopated flash since the timing relation of the dark and light periods has been changed. X/Vhereas, the normal flashing recall signal consists o roughly equal periods of light and dark, the new or syncopated signal consists of a prolonged period of light and a shortened period oi dark.

In the present system the attendants connector for local calling is controlled over a threewire circuit having the usual tip, ring and sleeve conductors. Inthe case where subscribers at a distance are to be reached a two-wire circuit is employed. The cord circuit makes connection to a three-wire connector circuit but this leans over a two-wire circuit to the distant connector. In this case the recall is made in the usual way by a momentary opening oi the ridge across ti e tip and ring conductors at the subscribers end of the line and this, in turn, starts the flashing recall circuit ci the cord to function. If a busy condition is encountered, however', the signal is passed over the two-conductor circuit from the distant connector to the local connector circuit by grounding of one of the two-conductors whereat the local connector circuit translates this into a circuit condition wherein thesecond synchronized interrupter in the connector circuit is superimposed on the regular interrupterrof the cord circuit to form this syncopated flash. In accordance with another feature ci the invention, therefore, o. diierential relay in the connector circuit is employed to respond to a single wire ground transmitted from the connector.

Reference is made to the copending Yapplications Serial No. 451,863, iiled in the name of C. D. Koechling, and Serial No. L151,362 filed in the name of H. H. Abbott von evenV date herewith, both of which applications cover inventions based mainly on the same disclosure as that herein set forth.

Other features will appear hereinafter'.

The drawings consist of nine sheets of circuit diagram. l

Fig. 1 is a schematic circuit diagram showing the general plan of operation and indicating the arrangement of the remaining iigures;

Figs. 2 and 3 placed with Fig. 3 to-,the right of Fig. 2 show a cord circuit and Fig. 4 placedY below Fig. 3 shows the operators telephone and dial circuit all used at the manual switchboard used in connection with a dial private branch exchange; I

Fig. 5 shows an outgoing trunk circuit cooperl ating with the cord circuit of Figs. 2 and 3 by means of which the operator may control the distant connectors of Figs. 6 and 7;

Fig. 6 shows a distant connector overvwhich an operator may reachany oneV of a group of individual lines;

Fig. 7 shows a similar circuit arranged for trunk hunting over which an operator may reach a group of lines arranged in subgroups;

Fig. 8 shows an operators connector cooperating with the cord circuit of Figs. 2 and 3 over which an operator may reach any one of a group or individual lines; and i Fig. 9 shows a similar vcircuit arranged for trunk hunting over which an operator may reach a group of lines arranged in subgroups. v

The system herein disclosed is a dial private branch exchange system 'so yond the capacity of the manual attendants board. It is common practice to .supplement a large that it is'bc-v dial private branch exchange system with a manualattendants board where incoming calls are answered and certain other special service is given. Generally speaking, a manual board has a capacity of about ten. thousand lines or can handle only four digit numbers. But it is possible to employ a system of much greater capacity for private branch exchange service. The present system is shown as a five-digit system, though it may be of even greater capacity.

Since the number of lines to be served is beyond the capacity of a manually operated switchboard the operator is not given direct access to any of the lines but selects an outlet bearing the rst three digits of the number of the wanted line and then dials the last two digits thereof. Thus, by way of example, if the operator wishes to establish a connection to line numbered 12345 she will insert her calling plug into a jack designated 123 and then dial 45. By thus setting up -a connection partly by a manual operation and partly by an automatic or dialing operation the operator at such a switchboard may reach any one of a number of subscribers more numerous than could be reached by conventional methods.

VIn Fig. 1 there are shown two ordinary private branch-exchange lines terminating in stations I and 2, each equipped with a dial. These station lines appear in a line nder 3 and by dial control may operate a first selector 4, a second selector 5, a third selectorv G and a connector 'I Yall in conventional manner. Thus these stations may be interconnected by ordinary and well-known means. As indicated in this schematic anyone of such ordinary stations may dial 0 and reach an operator through an answering jack appearance 8. Such a station by dialing the digit 9 may reach a central oice 9 over an outgoing trunk ID. In the same manner any one of these stations by dialing .8 may reach a distant private branch exchange I I over va tie line I2.

There may be provided certain special lines for'high ranking officials such as those terminating in stations I3 and I4 which do not appear in line finders, but on the other hand, have special switchboard appearances YI5 and I6, respectively, so that outgoing service is on a manual basis. These lines have appearances in the bank of the connectors so that they may be reached automatically.

Incoming central office lines and tie lines have manual appearances such as I'I and I8.

The operator may answer a call at any one y or"V the appearances 8, I5, I6, Il or I8 by means v`lish connections to any one of the stations of the private branch exchange. It is understood, of course, that the operator may also extend connections to the central ofice 9 and the distant private branch exchange II, but these arrangements are well known and do not form any essential part of the present invention. It may also be noted that the distant private branch exchange I I may be the same as the distant pri- .vate branch exchange indicated in the broken line rectangle in the lower right cornerof this iigure. In the one case the tie line vI2 leading to the private branch exchange is answered by the operator thereat and in the other case a connection maybe extended from jack 22 or 23 'directly to a subscriber in such distant private branch exchange. f

eonnetion' to ally." ofn olie" scribe atedrby' trie shown in Figs. 2 and 'redk "eircuit 3 is. arranged to dooperate With various lnes"provi"ded"with a connection to battery on Ithe =sleeves thereof. When of 'the rear cord 3| is inserted in the jack `associvthe plug ated" witha `lighted line-lamp; such" as that* assoeiatedwith `jack l5 for instance; a vCircuit Will be `Vestablished frem'battery on the sleeve of the asso'eiated" line circuit-through "the, sleeve Si Land thenceiin 'series through the' windings oflA and' through a small positivelbattery relays '33 of plug "to ground. -Both relays "33T and* 34 operate in this circuit-though the relay'iperformsno use- -fuVULnetion at this time.

`ture and 'front contactand "the winding 35"'t0" battery''tzvl'lereupon` vRelay 34 'operated elo'sesia 'circuit fromground through Yitsarma-` lof relay relay'- operates and at its' afl'rnature'` andY hackA Contact opens a circuit for relay 36. Through the" operation' of relay a Acircuit is closed 'from the tip of the 'plug Vv:SL-springs, 24 andV 3 ofthe ringing' key 3l, upper the 'key `arrrlature land front 'contact'ofz relay`35,

armature 3 and back Contact ofrelay'll, upper vWinding of relay' lll to ground; yAtV thesame time "a Circuit may be 'traced' `frolrrtlle-ring' of plugY 3l througdsprings 5 and d1 of the* ringing key' 3l,

lower A Winding the lower Winding of relay 4lto1bfattery. 38j and' lfboth dp'erate'due V'through the circuit just described "and orrelayS8,-fs'prings 'H and llfljof 'key 3S, armaturer 6 and backcontact 'of relay 4i), Relays to current llovvng over the elear'lnderstanding of thenature'of-'suchcal1-` he circuit referencel 'may be "had" to. the ap- "ing li plcatlon led by 'Bascoln "and Lambertyyerial Relay' 88 operated i-prer'fents*the rear 'cord su-` pervisory larnpI 32 from lighting Whilethe relay @1 l opeiatea 15e; Ntime.

formation from for the front Y "operating relays 43 and Min series.

rfo'rms luse flvll'ffunction fat this.` '55 Relay 43) operatedestablishesa cirelitf'from l{grourll "its armature and front 'Contact through leperatiol'r of relay 45. f 'Relay'i in" operating eslPtablisl'les; a circuit from ground,its"arnrature and relay 4G to battery whereupon Vrelay 46 becomes,V operated.

'circuit rnay'n'ow'be/tracedA from ground, rei 70 V.istarl'ee armature and 'front- `contantp-f relay 38,arlnature I Varldnbaek eontactiof relay 43,the lower Winding of relay 4l, springs fj a-nl pf key 349; frontontaet and armaturel5J of` relay 45 to battery. Relay 4l operates and locks in a circuitr V45: and rient Contact 'sol 60 thev ring-ing' current v'ilows winding of relay 38, springs 4 and 5 of ly'Fto the/ring or plugj ,3 i .v ThisY circuit,V though' closed z byxarrnature'- 2-of relay 45; isJ openedby armature il of relay"i Relayf` operated removes 35 thehusyftestleadtrom-the"t'ip---of-jthe front VAcord;'(oenneets the tip "-andj ringfof -the 1- cord through the contacts of relay51-and-disconnects `zyattery through-resistancegl thelring'of the front cord plug. AARelayY 45 operatedconnects 4o the Windingsjof relay-tothefrolltcontactsof s-anfl-frontcontaet of .contact 2 and armature l' to rand armature l of relay 45.

(D) No bridge is connected across lease causing relay 49 to operate under -of relays 55 vand 33.

33, armature 3 of armature 2 oi ground. The lighting of from battery, relay 45, springs Y and back contact of relay 50, winding of relayl throughl resistance 55 K through itsV front contact and armature'Z to the the callingstation as an indication that ringing current' is being connected to the called station line'.

When the receiver called station is removed from vthe switchhook the tripping relay 51 operates. The relay 51 thereupon substitutes the winding ol relay 52 to the tipand ring of the called line in place of the source of ringing current 59 and locks through'its lower winding, its

the front contact Relay 52, now in circuit with the called station, operates and causesthe front cord supervisory lamp to be extinguished and the relay 54 to operate through its lower winding. The circuit for relay 54 may be traced iromgroundresistance 55, armature and front contact otrelay 52, armature 3 and back contact of relay 53, lower winding of relay 54, front contact and armature 1 of relay 46 to springs 3 and 9 of key 33, front Contact and armature 5 of relay 45 to battery. Relay 54 locks in a circuit from ground, normal contacts of armature Il of relay 5B, armature 2 and iront contact of relay 54, upper winding of relay 54 through back contact and armature 3 of relay 55 to battery over the circuit hereinbefore described. Relay 54 therefore ylocks under control of relays 50, 45 and 46 and partly provides an operating path for relay 53.

From the foregoing wel can summarize as follows;

(A) Battery and ground for the calling station are furnished by the cord circuit through the -wiridings of relaysi4l and 33.

(B) Battery and ground for are furnished by the f cord circuit through windings of relay 52.

(C) The front and rear cords are coupled through condensers 63 and 64.

the tip and ring of thecord, except the ringing relay 61 which has no useful purpose at this time.

' When the receiver is replaced on the switchhook at the calling station, relays 4| and 38 re rIhe circuit for relay 49 battery, armature 6 and 45, springs 9 and 8 of key may be traced from front contact of relay windingof relay Vl5 through the normal contactsv relay 49, armature 4 and front contact of relay 41, back contact and armature of relay through resistance 43 to ground.

Relay 49 operated locks'through its frontI contactu and armature 2, iront Contact and armature 5 of relay 35, springs 1 and 6 of key 39 to ground. The rear cord supervisory lamp 32 is now energized in a circuit from battery, lamp 32, armature 2 and front contact of relay 35, armature 4* and front contact of relay 49, resistance 48 to: lamp 32 .operates as a disconnect signal.

When the receiver at the called station is replaced on the switchhook relay 52 releases cansing relay 53 to operate under control of relays .55, 4E and 45. A circuitV lfor relay 53, may be traced armature 6 and irontr contact of 9. and 8 of key 39, armature 3 53 through the normalcontacts oi-armature 2 of relay 53, iront Contact and armature l of relay 54, back contact and armature of relay 52 to ground. Relay 53 locks the called station,

and back contact of relay 5),V

control" normal contacts or armature 4 ci relay 53 to ground. Theoperation ofrelay 53`n'ow lights the front'cord supervisory lamp in a circuit which may be traced from battery, lamp 5l, front contact and armature 3 of relay-46, armature S and front contact of relay 45, front contact and armature l of relay 53, resistance 55 to battery.

l This lighting olarnp 5l operates as a disconnect Ii before the plugs of the front and rear cords are withdrawn from the jacks `the switchhook at the calling station is operated and released to recall the attendant, the relays 4i and 38 will release and reoperate. The relay in releasing causes the operation of relay in the manner hereinbefore described. Upon the reoperatlon of relay 38 the rear cord supervisory lamp is now connected in a circuit which may be traced from battery, lamp 32, armature 2 and iront Contact of relay 35, armature 4 and rcnt contact of relay 45, through the resistance 48 and in parallel therewith, the armature and front Contact of relay 38, armature I and front contact of relay 49 to the ashing recall lead 55 which essentially supplies interrupted battery to periodically shunt the lamp 32. This causes the lamp to ilash. The attendant then operates the talking and dialing key 62 causing relay 53 to operate which releases relay 45. Relay '45 released, stops the flashing of the lamp 32.

if the switchhook at the'called station is operated and released, relay 52 releases and reopcrates. Upon the release of relay 52 relay 53 is operated, as hereinbefore described. With relay 52 reope'rated the front cord supervisory larnp 5l is connected in parallel with the flashing recall circuit 55 n'a mannersimilar to that hereinbefore described so that lamp 5i now flashes. The attendant then operates -the talk and dial key @2, causing relay 53 to operate., Relay 50 operated'releases relays 53 and 54. Relay 53 released stops the flashing of the lamp. When the talk and dial key 32 is restored to normal,=r elay 5G releases and relay 54 reoperates, as described hereinbefore.

The above description applies to the use of the cord circuit when a connection is being made between two local lines as, for instance, a connection between the stations i3 and ill.l In the schematic shown in Fig. l it is not contemplated that the calling cord 2l will be used for A Vdirectly calling a local substation though it is capable of this-use in the manner .above described.` Y f y It should bejnoted that both the answeringand calling cords have two relays in their sleeve circuits, one otwhich is marginal. Thus, for instance, the sleeve of the answering cord has the two relays 3 3 and 34 in series,the relay 34 being marginal and only operating when a line sleeve o lower resistance is encountered. In the same manner the sleeve of the calling plug 42 has the relays 43 and 44 in series with it, the relay 44 being marginal.

It will be noted in the description to follow that thesleeve of the line leading toan attendants connector as, for instance, from the Yjack appearances 22 to 25, inclusive, has a high resistan-ce when it is selected and maintains this high resistance until certain operations are complete'd, after which the resistance is lowered. Therefore on a call from va station to another station via an attendants connector-the marginal relay of the calling cord will not be operated at first.

Y When completing a call froman attendants trunks, such as that terminating in Vthe jack 8, or from a manual station, such as those l'fei'nfli-V nating in the jacks l5 and I6, to a station via an attendants connector, the operation when the call is answered with the rear cord is the same as described hereinbeore. However, when the frontcord is inserted in the lack associated with an attendants Vconnector relays 43, 4'5 and @D operate since the sleeve resistance 'is high. Relay M operateddisconnects the relayrbattery supply trom therear cord but the calling station receives battery from the connector in the inanner which will be described hereinafter. When the foperators dial yis 'moved olf 'normal for the' first digit the rear cord is fed battery and ,ground from the telephone and dial circuit and the front and rear cords are separated in the dial circuit. The attendant then dials the two digits required to bring the connector to the desired line.

'The attendants connector will 'out through on the called' line iff it is 4idle and the battery and ground from the tip and ring or the connector will be removed. At this time the connector also changes the resistanc'elon the ia'ok sleefve from high Sto low. 'The change to a "low sleeve resistance causes relays 44 and 4S to operate which 'in tum -fcause's relay 4u to release; 'Ine release or relay dlreconnecfts relay M to the rear cord and separates the 'rear and iront cords by condensers es and fsa. The connector is nele olf n'orrnal under control ofthe sleeve after 'out through and the tip and ring ot the lront cord are connected to the back contacts yof the trilpping relay 51 to transmit machineeringing cur rent 'to the called subscriber.. Y Audible ringing tone is transmitted toward the rear cord through condenser 68 as herelnlcefore descrl'bed.- Relay 1S closes the windings 'of relay 52 to the-front contacts -of 'the trim-ing relay 51 to supply talki-ng battery to the called line after tripping relay 51 operates upon the response of vthe :called When the 'called stati'on'answersg relay 57 operases andrelays 52, '5S and 54 `function as fdescribed hereinbefore. The talkin-g, signaling; supervisionq disconnect Vand flashing recall will be the as described hereinloefore. Y

I the attendants connector yis dialed-.to a busy line the sleeve becomes low in resistance and the battery and ground on ythe tip and ring of the connector are removed and replaced by a bridge intermittently applied. The ringing from the cord is tripped 'through ythis bridge. Il the zat'- tendant has restored the talk and dial :key 62 the intermittent bridge 'across the tip :and ring" will operate and 'release relay fst'arting the flashing recall signal 5i on the front cord lamp. If theattend'ant :has not :restored the talk and dial key E2 she will `receive -an audible busy indication.

It is particularly to be noted that the interrunter in the attendantfs connector circuit which intermittently applies the bridge to ti'letip and ring ci the calling cord 62 is of 'onfeelialf the rate of' the interruptor 6 6. By way of example,

the'interr-upter 66 applies batteryv to the lead 65 V at the rate of 1,20v impulses per minutewhile the 'interrupter in the attendants connector circuit runs at the rate of v6() interruptions per minute.

- Since the interruptor in the attendants connector circuit operates the relay 52 it will there'- fore render the dashing recall circuit of this cord circuit electve on yevery other interruption thereof so'thatthe effec-t is that the lam-p 5i will be vlit approximately three-tenths of a .period and dark the other .Seifen-tenths thereof. The -signal for the recall is a steady ilash-ing at the rate of 12S interruptions per minute, while the signal for the encounter of a busy condition is this tso-called syncopated signal wherein every other nash of the signal in its ordinary working is rendered eiective, Since the interrupter of the attendants conneclxnr circuit and the interruptor 6 .are both operated trolhmthe -same power plant they may Aboth be on the same shaft and the relation between them maybe fixe The ope-ration of the oord circuit cn a connection between a central olce call and a station is as follows: the incoming central ollce call is answered with the rear cord 3l Yin the usual manner and theoperation is. different from thatdescribed hereinbefore in that a high sleeve resistn ance .is lencountered which docs not allow the marginal relay 34 to respond. Since the inarginal relay does not respond, therefore relay 35 does not operate.

As a result a connection is established from ground-y springs Ei and 7 of key 39, amature 5 andl back contact ci relay 35, front Contact and armature lof relay 33 winding of `relay 36 Ato battery. is a result of the operation yof relay 36 a connection may be traced from -ground at the armature and back contact Aof relay $4, armature 4 andlfront contact of relay 6, winding of relay 48 te battery andground whereupon relay 4G becomes operated. The operation of these relays connects a bridge across the cord which may be traced from fthe `tip of plu-g 3l springs and 3 of the ring-ing key 37, fron-t contact 'and armature 3 yof relay 355, retardation coil 8-, armature 4 and back contact of relay 4l, armature 8 and iront contact ofrrelay 35@ springs 4 5 of ringing key 3J to the ring -of plug `3l 'I'hisjbridge serves as a signal' on the central office line lthat the call has been answered and will .serve to trip ringing and .perform the other usual lfunctions required 4in a caseof this kind.

Whenthe Sir-.ont 'cord is-inserted in the jack of an attendantsfconnector relay 33 ,operates and causes the operati'ongof relay 47 Aon its' lower winding. .Y l

A circuit may be traced from ground -on the tip of cord 3l, springs 2 and '3 'of ringing key 31", upper winding of relay 38, springs 1f!A and 5 of'key 39, Afront Contact and armature 'l of relay 46, springs 6 and 8 of key'BZ, springs l`2 and i3 of key 39, springs il and li cf vkey 6l back contact and armature @-f''relay 8, front Contact and armature 5 of relay 45, to the ring of plug l! it elleomrters battery in the :circuit of the attendants connector. Likewise, a clzcult'may be traced from .battery on 'the ring 'of cord 31 springs 5 and 4 of key 3],lower winding of relay 38, springs H and l0 or key 3S, front Contact and armature 2 of relay 4U, 'springs 5 and 3 of key 62, springs 3 and 2 of key M, springs' 3 and 2 of Ekey El, back contact and armature 3.0i relay 45 frontcontact and armature 4 of .relay l5 .to

the tip of plug 42 where it encounters ground in the-circuit` of the attendantsconnector. Relay 3S responds and closes Va circuit from gro-und, resistance 6,8, armature and front contact of relay 33, armaturev land back contact of relay 59, lower winding of relay 41, springs 8 ,and 9 Vof key 39,

front contact and armature of relay 45 to cause the operation of relay t1.,

Relay 38 will release when the dial is moved off normal but relay 59 will not operateand relay 41 will release since the talk and dial key 62 is operated. ,Moving the dial ofi normal separates the front and rear cords. The attendant then dials the two digits to direct the vconnector to the desired line.

The attendants connector cuts through on the called line if it is idle, removing the battery and ground from the tip and ring and changing the jack sleeve resistance associated with the front cord to a lower value. Thus relays 44 and 46 will operate but relay 4i. remains operated under control oi relay 3Q. The tip and ring of the front cord are then connected to back contacts of tripping relay 51 for the transmission of ringing current. The calling lamp 5l will also light at this time.

When theV called station answers the tripping relay 51 operates and closes through the tip and ring of the front cord. The ground that locks relay 51 operated also passes over lead 69 to the telephone circuit and causes a relay therein to operate and furnish talking battery to the called station until the talking key is restored by the attendant. When the talk and dial key 62 is restored to normal the battery and ground from the central cnice is fed through the windings of relay 38 to the called station. Relay 38 will operate and extinguish the callinglline lamp 5i at this time and relaylil will operate, opening'the short circuit about resistance 1U whereby less current from the central oilice line is drained by the bridge and a greater amount allowed to flow to the called station. The operations in this connection may now be summarized as follows: (A)V Talking battery for the called station is iurnished from the central office. (B) A high resistance bridge consisting ofthe winding of retardation coil 68 in series withthe resistance 19 is bridgedv across the tip and ring of the rear cord. (C) The supervisory relay 33 is under control of the called station.

When the receiver is replaced on the switchhook at the called station the circuit functions, as described hereinbefo-re, except that relay 38 is under control ci the called station and the operation of relay i9 causes the front supervisory lamp to light as a disconnect signal and shortcircuits the resistance 10, thereby decreasing the resistance of theV bridge'across the-cord.

VFlashing recall is controlled by relay 38 in conjunction with relays l1 and 49, as described hercinbefore. However, sincerelay 35 is not operated the supervisory lamp 5| of the calling cord is flashed rather than theanswering cord lamp 32. l

, If the called station is busy the sleeve becomes lewin resistance and the battery and ground are removed from the tip and ring inthe connector and replaced by a bridge which is intermittently applied. If the talk and dial key G2 has been restored to normal the application of this bridge will cause the supervisory relay 38 to operate and release, thereby starting the flashing recall signal on the front cord lamp. Ifthe attendant has not restored the talk and dial key TELEPHONE AND DIALING CIRCUIT ARRANGED USE WITH ATTENDANTSCONNECTGRS,

When the tip of an associated cord, for instance, plug 62, is touched to the sleeve of a busy station line, tie trunk, attendants connector or trunk jack, ground or positive potential from the busy sleeve charges'condenser 1l through a winding of the repeating co-il 12 and resistance 13 to the front contact of relay 14, this relay being energized through the transmitter 15 of the telephone set. This induces a busy click through the winding of the repeating coil 12 at the attendants telephone receiver.

Fos

Talking When the talk and dial key 62 of an associated cord circuit is operated the leads 15 to 80, inclusive oi the telephone and dial circuit are Connected to the cord circuit, thereby closing the tip, ring and receiver leads and providing a talking circuit for the attendant. The attendants tran.,- mitter circuit may be traced from ground, the right-hand winding oi repeating coil 8i, through the tip of jack 82, transmitter 15, the tip of jack 83, the winding of relay 14 to battery. Speech currents from the transmitter 15 are then transmitted by the left-hand windings of repeating coil 8l, through the back contacts 'and armatures 2 and 4 of relay 84 to the talking conductors 85 and 8E. The operators telephone receiver circuit may be traced from conductor through the back contact and armature of relay 81, back contact and armature l of relay 84, the sleeve of jack 82, thetelephone receiver 88, the sleeve of jack 83, armature 3 'and back contact of relay y84, the mid-point tap on the left-hand winding of repeating coil Si through the condenser 89, back contact and armature 4 of relay 84 to conductor 35. Through the back contacts and armatures of relay 9i) this talking circuit is connected to conductors and 11, leading to the front cord 42. Through the armatures and contacts of relays 9i and t2 this talking circuit is connected to conductors 18 land 19 leading to the tip and ring of the rear cord 3 l Dialing In order to dial on a cord circuit the talk and dial key 62 of the cord circuit is operated'. When the dial is moved ofi normal relay 93 operates in a circuit which may be traced from ground, springs 2 land 3 of key 94, the orf-normal springs of the dial 95, winding of relay 83 to battery. Through its front contact and armature 2 relay 93 shortcircuits resistance 93. The operation of relay S3 also results in the operatic-n of relays 91, 81 and 90. The circuit for relay 91 may be traced from battery, winding of relay S1, front contact and armature 3 of relay 93 to ground. The circuit for relay 81 may be traced from battery, winding and this relay thereupon'fully operates Aand attracts all of its armatures.

In its normal condition a from battery, tact of` relay |09, through the back contact and armature 3 of relay IIS to the idle indicating lamp I I3. Therefore, upon the operation of relay |09 this idle indicating lamp is extinguished and the battery connection is extended by armature 270i relay |00 to its front contact to cause the lighting of the next idle indicating larnp.

Upon the operation of relay |88 the tip conductor is extended over armature I and front Contact of relay |08, the upper left-hand winding of repeating coil I2I, back contact and armature 4 of relay H0, the upper winding of relay I|2 to ground. In a similar manner the ring of jack |01 is extended from armature 2 and front contact of relay |08, the lower left-hand winding of repeating coil |2I, back contact and armature E of relay IIO, the lower winding of relay H2 ,to battery. Due to a reversal in the cord circuit hereinbefore explained, relay IIZ becomes operated. The operation of line relay H2 connects the windings of the polarized relay IM to the distant connector circuit which has arelay facing the line to this trunk circuit. vThis connection may be traced as follows: from ground, through the lower `winding of relay IIB, armature 2 and circuit is established.

front contact of relay IIZ, vthe lower right-hand winding of repeating coil IZI, conductor I i5, back contact and armature 4 of relay |23 to conductor |25 and a similar circuit from battery, the upper winding of relay IIII, armature I and front contact of relay H2, the upper right-hand winding of repeating coil |2I, conductor IE6, baci; contact and armature I of relay |23 to conductor IM. Relay H4 operates in vthis circuit and rcauses the operation of relays II1 and IIS. A circuit may be traced from battery, contact and armature 3 of relay IIE), armature and left-hand contact of relay I I4, armature and back contact ofrelay IIS, armature 1 and back contact of relay I I0 to ground. Relay I I1, in operating, connects ground through its armature 2 and front contact to the winding of relay I i8.v

When the attendant dials, relay ||3 follows the dial pulses and opens the line 'to the 4distant The polarized it releases.

dial pulses as repeated by connector each time relay IIA follows the relay ||2 but the slow-release relay operated.

When dialing is completed the distant connector circuit inserts a high resistance into the line causing relay IM to release. relay IM causes the release of relay |II which, due to the slow releasing characteristic H8, results inthe operation of the cut-through relay IIB. from ground, armature I relay |09, armature 2 and and front contact of front contact of relay H8, back contact and armature I of relay II1`,

the winding of" relay ||0 to battery. Relay'I I0 locks through its armature 5 and iront contact and the iront contact and armature I of relay |09 to ground.

The operation of relay H0 causes the resistance in the sleeve lead to change from high to low. Up to this time the winding of relay |09 which has a high resistance is connected to the sleeve of jack |01 but upon the operation of relay IIS a lower resistance IZIJ` is placed in parallel with the winding of relay |00 so that the marginal relay 44 in the cord circuit now becomes operated. The operation of relay III) also through armature 2 and back conwinding of relay I I1, back Ill .n0-lds The release of of relay A circuit for this relay may be tracedv connects a condenser |20 across the middle of the side of the repeating coil facing the distant connector and prepares a circuit for connecting the windings of relay H4 with polarity reversed to the leads of the distant connector throughV normally closed contacts oi' relay H2 and the windings or" the diiferential relay IIE?. The operation of relay I I0 opens the circuit of relay |I2 so that this now releases. Relay IIO also prepares a circuit for giving a closure to the cord circuit through the contact of the polarized relay IIs.

The change in the sleeve resistance to the cord circuit resulting in the operation of the marginal relay s causes the cord circuit to send out ringing to this trunk. The ringing current causes relay E22 to operate which results in the operation of relay |23, thus causing a clear path from the tip and ring oi the jack |01 to the line conductors IM and |25, respectively.

when the called party answers or when the distant connector connects a low resistance ground to the ring lead as a line-busy indication during the ringing interval, the tripping relay in the oord circuit operates and removes the ringcurrent, causing relays |22 and |23 to release. The release of relay |23 again places the polarized relay H4 incircuit to Operate over the station loop if the line is idle. If, on the other hand, the line is busy and the operation just described has been caused by a low resistance ground to the ring lead, then the differential relay IIQ will be unbalanced as a busy indication and instead of connecting a bridge across the tip and ring of jack |61, will now connect interrupted ground to the ring of jack |01, leaving the tip thereof open. ln case only relay H4 operates a signal that the called party has answered, acircuit may be traced from the tip of jack |01, armature I and front Contact of relay |03, the upper left-hand winding of repeating coil I2I, front contact and armature 1 of relay ||0, back contact and armature of relay I9, left-hand contactv and armature of relay IIs, armature 3 and .1, front contact of relay III), the lower left-hand winding of repeating coil |2I, front contact and armature 2 of relay |08 to the ring of jack |01. In case the signal coming from the distant connector is a low resistance ground on the ring, thereby causing the relay ||0 also to operate, a connection may be traced from the ring of jack itl', through armature 2 and front contact of relay E33, the lower left-hand winding of repeating coil |2I, front contact and armature 3 of relay I I0, armature and left-hand contact of relay IMI, armature and front contact or relay H0 through retardation coil |21 and interrupter E23 to ground. Upon the iirst open period of this circuit, the flashing recall circuit in the cord will be prepared for operation and then put into operation upon the next closure thro ugh the interrupter |28. Thereafter the signal displayed in the cord circuit will be modied by the interrupter |26. Since this is of one-half the rate of the interrupter causing the iiashing recall signal, the result will be a totally different kind of visual signal in which the display is of approximately three-tenths of the period and the dark condition of the lamp is approximately seventenths of the period. In other words, every other iiash of the lamp in the iiashing recall circuit will be eliminated. As mentioned hereinbefore, the interrupter |28 is synchronized with the interrupter 66 of the cord circuit so that the relation between the two s xed.

aannam nished through the windings of relays. H4, HS

and the repeating coil I 2 l.V The contacts of relay H4 maintain a. closure toward the cord circuit and relay IMY Will receive switchhook flashing from the called par-ty to the cord circuit so, that a flashing recall condition may be set up in the ordinary manner by the subscriber reached through the distant connector.

When the plug is removed from the jack, relay |99' releases causing the release of relays |08 and m. The release of relay HG causes the release o f relay H1' and relay IH, except that this latter relay may have already released ldue to the called partyhanging up. Therelease of relay ||1 causes the release of relay H8 which causes the idle indicatingrlamps to lig-ht and restores the circuit from the lowerl winding of relay |08 to the ring of the jack |01 so that it can operate on the next call,

Connector circuit for completing calls from attendant at distant private branch exchcmg to station Zines-Fic `(i Upon the seizure of the circuit shown in Fig. Sand the operation of the line relay- Hlthereat, battery and ground are connected through the windings of relay H4 to the conductors |24 and |25 which extend to. the upper andV lower windings, respectively, of vline relay |29. Relay |29 operates from batter-y on the tipr and ground on the ring of Vthe trunk circuit and causes the opleration of the rst slow relay |30 in preparation for pulsing'. v c

n the first open period relay |28 releases and establishes a circuit from its armature I and' back contact, through armature Iv and front contact of relay |39', springs i and 3 ci the vertical oil*- normal spring combination |3|,` through the windings of slow-release relay |32 and the vertical magnet |33 to battery. Relayl |32 operatesY before the vertical magnet'steps the switch, opens the circuit of relay |34 and closes its own locking circuit to spring of the vertical oi-ncrmal springs |3|. When the switch steps and the vertical oir-normal springs operate, the original operating circuit for relay |32 and magnet |33 will bejopened but a substitute circuit throughrthe armature of relay |32 will be closed in its placev Without interrupting the steppingcireuit. When the line relay |29 reeperates theuvertical magnet releases, but relay |32 being slow to release holds until the end of the train of impulses comprising the rst digit.v

The switch thus continues to step Vertical until the end of the train ation o1' relay |129 releases relay |32.

@n the second digit, ywhen relay |23 releases, relay |34 and the rotary magnet- H operate. The circuit maybe tracedifrornarmature and back contact of relay |29z armature and front con,- tact of relay |33. ,springs 6 and 5 oi the. vertical oli-normal. spring combination |3|', armature and hack. contact of relay |33. armature .4 and hack contact Qf relay |36, through the Winding c f relay |34 to batteryand in parallel therewith through armature 4 and hack contact of .relay l 31 ,ano the winding of rotary mascot |35 to battery.

The rotary magnet and relay |34 oro multiple and the lotterrcloy bci-.ns slow to reloose remains operated during pulsing while the rotary mas.- nct stops the switch. to the desired terminal.

of impulses when the oper"-V armature: of relay |34, front Contact o Testing the linee-.Eine busy Whoo the switch is on the line to which it. has been dialed'anol before theslow-rcleose. relay |34. releases. thc Sleeve ofthe called lino is concocted to relay |38. A circuit maybe traced frein hattcry through the Winding of relay |38, front contact and armature. Z of relay |34'. Slccyck brush |39. to the `sleeve terminal of the called 01.1 a busy line the sleeve will be grounded. thereby operating relay |38., When' relay :3.4 releases, relay |38. locks. through tho normal. contacts. of and. armaf ture 2 or relay |38. armature 3 and front contact of. the lrst slow-reIeasing relay |34 izo-ground.

Relay |8.'o1o.crote.d; opens the circuit of relay |31 and operates relay |36- '.Ihis circuit may bo trascorrono battery., Winding of relay |36',

ture .3 and baal; Contact of relay |.3!|,.fro1 1.t contact and armature 3 of relay A|.3-l to ground. Relay |36 operated, (1l cocos the circuit of; relay |31| and the circuit oi rotary .magnet |35, (2,), removes the line relay f2.9. from thc tio and rms, thereby causing the release. ol relay |23. and (3.2 connects high resistance relay MQ through the armature and'bacl; contact of relay |4. and the. front. Contact, and armature of relay |36, to the tip wire |24, and high resistance relay |42. through armature. 5. and back Contact of rcloy |43, the.. front. VContact and armature 4 of relay |36y to. the rins'conductor |25. Relay |42 oporates to ground on the ring, at the distant. end of the trunk and holds the first slow relay |34@ operated.

Removing the lino; relay |29 from the tip and ring is 'a signal to the trunk. at the distant private branch exchange. to prepare, to ring, or to receive busy ashes and Wherrtlie trunk is thus prepared it reverses battery and ground to the connector circuit. Relay |42 thon releases and relay |40 thon operates.. Relay |40 closes resistance |45 across the windings of relay ,|23 which thereupon operates and holds the rst Slow relay |30. opel',- ated.Y Relay |29. also completes the circuit to relay |43 through tho armature 2 and front contoot of relay |29, armature 3 and, front oontactof relay |36, to ground. Upon operating. relay |43 establishes a' Connection from ground, armature 2 and front contact o1' relay |43, front contact andarmature of relay la to the ring conductorA extending'to the Vcnitgoing trunk circuit, Fis.' 5. whore itrcsults in unbalancing the differential relay IS for the purposes hereinheforo described.

When thc called lie is idle, the sleeve brush |39 will encounter a batteryvconncction instead of ground andrelay |3l| in releasing at the end of the rotary stepping movement connects relay |31 to. the sleovehrush. This circuit may bo traced from sleeve brush |39 through armature 2 and back Contact ci relay` |34, upper winding of relay |37, back contact and armature 2 of-relay |38, armature il and front Contact of the rst slow. relay vitil. Relay |31 becomes sufficiently energized in this circuit to move its armature 2 which closes a circuit from ground, armature 2 and frontcontact of relay |30, front Contact and armature 2 of relay |31, lower Winding of relay |371, through rotary magnet t0 battery.V This causesv the frull energization of relay |31 and at the same time stops iurthor action of the rotary magnet. VRelay* |31 connects direct ground .for- Ward to the line circuit sleeve through its. ,front contact and ormaturc to hold. tho out-.oli relay of the called lino and to busy the terminal to other switches.- Relay |31 also opens the original energizing circuit -or the `rotary magnet and opens the release path through its armature 1. Through its armatures and 3. relay |31 partially closes the tip and ring rconductors tothe called station; L v

Upon the release of relay |34 and thevoperation of relay is'i, a circuit is established from ground through the front contact and .armature 5. of relay ll, back Contact and armature 3 of relay |35 tothe winding of relay |36. As hereinbefo-re described, relay |36,'upon operating, Yremoves the line relay |25 from the tip and 1ing and closes the two high resistance relays |40 and |42, respectivelyjto the tip and ringof thetrunlc.v Relay |42'holds irst slow relay |39 operated until battery is reversed by the trunk circuit atY thev private branch exchange. Relay |42 then releases and relay |45 operates. Relay |40 again causes the operation of the line relay |29 to complete the circuit to relay |43 which now" operates.V Relay |43 operated connects the tip and ringer the trunk from the distant private branch exchange to the tip and ring of the called station. The tip conductor |24 may be traced through the Vupper winding of the supervisoryrelay |42, through armature I and front contact of relay"|ll3, front-contact and armaturey i of relay |31 to thetip brush |45 of the connector which is now in association with the l tip of thev called line |51. The ring conductor '|25 may be traced through the lower winding of relay'lflfl, armature and front contact of relay |43, front contact and armature 3 of relay E31 to the ring brush |42 of the connector leading tothe called subscribers lstation |41. Relay |43, in operating, opens the circuit of relay |42 but relay |40 is still connected to the tip so that the linerelay |29 remains operated.

During the ringing of the station frornrthe distant private branch exchange, relay |50 holds to the ringing ground on the tip.. Relay |44, whose lower winding is in series withthe ring, may .operate on the alternating currentand operaterelay Edil. This will Vopen the winding ofre'lay |50 .but its lower contacts perform the sarne function as the lower contacts of relay HilllsoV that theline relay |25 remainsvoperated to'hold the connection. When the called fstationanswera. ringing is tripped and relay |44 operatesv on the station loop to remove relay |45 from the connection and hold the connection through the operation of relay |4| as described. vUpon disconnection by the called station relay |44 'releases and causes relay |4| to release, but relay |40 then operates to ground on the tip to hold the switch. When the cordris pulled down at the private brauch exchangev after the called station disconnects, relay |40 will release thus releasing the line relay |25 and the first slow relay |30. Relay |35, in releasing, opens the circuit for relay |31 and now acircuit may be `traced from ground, armature l and backcontact of relay |20, armature and back contact of relay |30, back contact and armature 'l or relay |31, springs |l and 2 of the vertical oil-normal spring combination |5 to release magnet |49 and battery. Release magnet |49 is operated and causes the brushes 145, |48V and |39 to leave their position inconnection with the terminals of the called line. Thus, the'switch is returned to no rmal. The release of relay |31 causes the release of relay |36 and the release of relay |28 causes the release of relayV |43,

0n disconnection 'by the attendant from a busy connection, relay Main releasing, releases the line relay |26 and the first slow relay |35. Relay |35 then releases relay |35 which, in turn, releases both relays il and |43. Withrelay |30 released, the release magnet te restore the switch to normal.

Connector circuit-Rotary hunting-For completing from attendant at distant private branch archange to station Zines-Fi/- 7 rihe operation of this connector is in many respects similar to the operation oi the connector in` Fig. 6. When the attendant at the distantV private branch exchange selects this trunk', the lineA relay |56 operates trom battery on the tipy and ground on the ring of the trunk circuit at the distant private exchange. Relay E50, operated, operates thefirst slow relay |52 which prepares the circuit for pulsing, f On the iirst open period relay |56 releases operating the second slow relay |52 in series ywith the vertical magnet |53, through the springsof the vertical ofi-normal contact cornbination |54. Relay |55 being slow to release will remain operated during pulsing; Relay |52 operates before the vertical magnet steps the switch, opens the circuitof relay |55 and closes its own locking circuit to the vertical oiuior- .al springs. When the switch steps and the vertical cit-normal springs operate, the original operating circuit of relay |52 will be opened but the holding path will be completed without interrupting the stepping circuit. When the line relay |55) reoperates, the vertical magnet releases but relay |52 being slow to release holds until the end of the digit. The switch thus continues to step vertically until the end o 'he digit when theoperation of relay |55 releases relay |52. -On the second digit when the line relay |50 releases, relay 55 and the rotary magnet operate. Relay |55 being slow to release holds over pulsing while the rotary magnet steps the switch to the desired. line terminal which may loe-either an individual line or vthe first yor" a `group of lines. Y

Before relay |55 releasesat the end of rotary stepping a path is closed from the sleeve Wiper |56 of the connector switchvthrough armature 2 and front contact of relay |55, armature Vand back contact of relay |51 to the winding of relay |53 and thence to battery.l A busy line will have ground on the sleeve which will operate relay |58. When relay |55 releases, relay |53 locks to the sleeve ground through its armature 4 and front contact and the normal contacts of armature 2 of relay |50 to the sleeve wiper |56. Re-

lay |58 at this time causes the operation o1 relay |60 in a circuit frombattery, winding of relay |60, back contact and armature of relay |55, front contact and armature 2 of relay |58 to conductor I6! supplied with ground over armature 2 and front contact of the first slow relay |5| Relay |60 operated, (l) opens the circuit of relay |55 and the circuit of the rotary magnet |62;

(2) removes, the line relay |56 from the tip and ring which now releases; (3) connects high resistance relay |53 to the ring conductor |25 and high resistance relay |64 to the tip conductor |24; and (Ll) closes a circuit from relay |65 which may be traced from battery, the winding of relay |55, armature and back contact of the rotary magnet |62, normal contacts of varmature 2 of relay |05, front contact and armature 5 of relay |58, armature and front contact of relay |60,

Images