US1570022A - Automatic telephone system - Google Patents

Description

Jan. 19 1926. 1,570,022

J. wlcKs AUTOMATIC TELEPHONE SYSTEM Filed Oct. 23, 1918 6 Sheets-Sheet 1 I J. WICKS AUTOMATIC TELEPHONE SYSTEM Filed Oct. 23, 1918 6 Sheets-Sheet 4 Jczhn ZIL/ZEKE .flilv-i Jan. 19,1926. I 1,570,022

J. WICKS AUTOMATIC TELEPHONE SYSTEI Filed-0ct 25 mm 6 Sheets-Sheet 5 Zy-i J. WICKS AUTOIA'IIC TELEPHONE SYSTEM 6 Sheets-Sheet 6 Iniran"lur--- Filed Oct John Hwks A 4 i fig:

Patented Jan. 19, 1926.

UNITED STATES PATENT OFFKIE.

JOHN WICKE), OF CEIICAGO, ILLI NOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed October 23, 1918. Serial No. 259,323.

To all whom 2'13 may C0.?26'6?72-.'

Be it known that 1, Joint Wicks, a citi- Zen of the United States of America, and a resident or". Chicago, in the county of Cook "and State of Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following 18 a specification.

My invention relates in general to au to-' matic telephone systems and more spec1fically to an improved trunking arrangement for use in calls between exchanges, and improved switching and repeating mechanism 8 for controlling automatic switches over two lector repeaters are therefore controlled over a loopcircuit in a standard way but may in turn transmit impulses over composite or other similar circuits in a manner to be pointed out. These and other objects of my invention including improved methods of supervision will be pointed out more indetail later.

Referring to the drawings, Figs. 1, 2, 3, t and 5 when placed end to end with Fig. 1 the left show the various switches and circuits which are used to establish a conncction from a calling substation A. Fig. 1 to a called su istation' B Fig. while Fig. 6 shows equipment which may be used by an operator in connection with the equipment o1 Figs. 2 to 5, inclusive, in establishinga similar connection from the substation A to the substation B. y

In Fig. 1 there is shown a substation A of well known 2 wire type having a line switch G individual thereto, which line switch is of stancard rotary type and which Operates when the receiver at substation A is removed to automatically select an idle trunk line leading to a selector D. The selector D is of well known Strowger two wire side switchless type of selector which responds to the calling device impulses to elect a group of trunk lines and then automatically selects a trunk line in the elected group which in this case is shown as leading to a repeater Eassociate'd with a trunk line to a distant exchange.

This repeater E is then operated over two sides of the line by the calling device at substation A to in turn transmit impulses over a composite circuit superimposed on the trunk line in Figure 3 to a combined selector and repeater F, Figure 4.

The selector repeater in Fig. 4 operates in this instancefas' a regular selector to seize an idle trunk line extending to a connector H Fig. 5, which is of standard type, and which is then operated by repeated impulses to find a called line such as that of substation B'.

The operator referred to in connection with Fig. 6 may be a toll operator, paystation operator, complaint and information operator, or any other kind of operator such as is usually found in automatic exchanges. These operators according to well understood practice are provided with outgoing trunks over which they have access to theregular exchan e trunking system and which may be usec for connecting various kinds of lines terniinating at their positions with called subscribers. These lines may be toll lines, p'aystation lines, or complaint and information trunks, etc}, but for convenience a well known type of manual subscribers line is shown, terminating in the jack J at an operators position. The operator is provided with a plurality of cord circuits such as the cord circuit 0, by means'ot' which the line of station A and other lines of the types mentioned may be connected to outgoing trunks such as the one terminating in the jack J. The cord circuit 0 is of well known type such as is shown and described in the patent to Martin, #1291586, granted Jan. 14, 1919. The selector D, in which the outgoing trunk extending from jack J" terminates, is similar to selector D, Fig. 1.

I will now describe the operations in de tail when a subscriber at substation A initiate-s a call.

hen the receiver is removed. a circuit is closed from battery through slow relay 2, over the line to and through substation A, back over the other side of the line and to ground. Relay 9, energizes to close a series circuit from ground through springs 3, relay t, and magnet 5 to battery. At the same time, h-:. ref springs 6 extending from private wiper 7,

, another circuit is closed at through springs 8 and 9, springs G, springs 10, and magnet to battery. Now if the trunk line on which the wipers oi the switch C is resting, is busy, a ground will be pres cut on contact 13 which will therefore shortcircuit the high resistance relay 4; in the series circuit first t need and will cause magnet 5 to operate to step the wipers of switch C over busy contacts until an idle trunk is found at which time, relay 5 is no longer short circuited and energizes to cut the line circuit through to lirst selector D and disconnect relay 2 and ground from the line circuit. llelay -i held energized by ground thrtuigh springs 3 until a ground is fed back over the private from the switch ahead. As soon as relay l: energizes a c rcuit is completed for the line relay ill ol. selector I) over the line circuit to substation A in the usual manner. Relay Llenergizes relay 15. which in turn grounds the release trunk, and prepares a circuit for slow relay l6 and vertical magnet .17 in series. Relay ll is now controlled by the calling device to fall back a predetermined number of times and thus complete the circuit of magnet 17 and relay 16 at springs 18 and 19. Magnet 17 operates to raise the wipers 20, 21 and 22 to some level of the bank. Relay 16 closes a circuit for rotary interrupter relay 93 which ener gizes and prepares a circuit for rotary magnet 24 at springs 25. lVhen the impulses for this first digit cease and relay 16 falls back, a circuit is closed for rotary magnet Q-l at springs 26 and 27 and springs Magnet 24: upon energizing, opens the circuit of relay 23 at interrupter springs 28, thereby allowing relay 23 to fall back. Magnet 2% at the same time rotates the wipers 20, 21 and 22 onto the first set of contacts in the desired level. If this trunk line is busy a ground will be present on the private or test contact thereof and will immediately reenergize relay 23 from wiper 22 through springs 29 and 30, springs 28, of? normal springs 81, and relay to battery. Relay 23 will again close the circuit of magnet 24c and this operation will continue until an idle trunk line is found. lVhen such a trunk is found there will be no ground to energize relay 23 and relay 32 which has heretofore been short circuited by the ground on the private wipen energizes over a circuit from ground at relay l5, relay 32, springs 28, springs 31, and relay to battery. Relay 32 being of high resistance does not permit relay 2?) to energize.

Relay 3:3 upon energizing, disconnects the line relay 1-1; from the extended line circuit and cuts said line circuit; through its front contacts to line wipers 2t) and 21. A locking circuit is also closed for relay 32 which extends over the above traced circuit but will later get its ground from the switch ahead through wiper 22, and springs 29 and 33.

As soon as the line circuit is cut through to the repeater E, and before the relay 1:) falls back, a ground impulse is sent over the private wiper 22 through springs 2H: and 15, springs 36 and 37, and through relay 38 to battery. Relay 38 upon energizing, prepares a locking circuit for itself at springs 23$), and connects the line relay it) across the line circuit and in series with the substation A. Helay d0 now energizes and closes a circuit for relay ll at springs at). and sill. lelay ll upon energizing connects ground to the holding circuit of relay 38 through springs (32, 3 and 39 and on to the relay 32 ot' the selector, and also closes a circuit for the rerersing relay 44-, which relay =l-l is however immediately cut of by the emj-rgization of relay to as will be explained. ltelay it also prepares an impulsing circuit at; springs 4t,

and -l-7 and prepares a circuit for relay 4!) at springs 4h. The im 'iulsing circuit closed by the joint action of relays -lt) and it e);- tends from battery through the upper winding of relay to, springs 50. springs 4-7 and 4:6, conductor 51, upper composite coil 52. trunk line conductor 53. coil :i-h cmuluctor springs 56 and 5?, springs 58 and 59, and upper winding of relay (it) to ground. Relays l5 and GOcnergize over this circuit. Relay opens the circuit: of relay it at springs (34: before that relay has time to energize as has been pointed out. o now have the line relay 60 of the selector repeater F energized in series with the conductor 51 and the relay 45 through the contacts so of line rclay of the repeater E.

As the calling subscriber at A now open ates his calling device for the next digit of the called number the relay 40 falls back a number of times to deliver inlpulses to relay (it) over the above circuit. During the operation of relay l0, relays H and 49 are both held energized by ground from spring 42. Relay 49 while energized, closes a low resistance shunt; circuit: about the winding of relay 4-5 at springs through resistance 66 and opens another point in the circuit of relay i lat springs (57. Each time springs 50 separate relay falls back to ClUSt a circuit for magnet 68 and relay (it) in series. l vheirrelay (it) first energized it closed a circuit: from ground through springs 70 and 71, springs 72 and T 3, and relay 7- to battery. Relay Tl energizes to ground the normal private through springs N and 7t prepares a circuit for relay 9 and magnet 68 and closes the circuit of a high resistance polarizing winding of coil 77. Each time the magnet 68 energizes the wipers 78, T9 and are raised one step until they stand before a desired group oi" trunk lilies. Relay 69 upon energizing and after the shaft has taken its first vertical step closes a circuit from ground througl'i springs 75 and 76, springs and 82, springs 83, and rotary interrupter relay 8% to battery. Relay 84.

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upon energizing, prepares a circuit for rotary n'r-agnet- 85 at springs 86. When re lay .69 falls back after this digit the circuit of magnet 85 is closed through springs and 76, springs 81 and 87, and springs 86. Magnet 85 therefore operates to step the wipers 78,79 and 80 onto the first-set of contacts of the elected level. Relay 84 also closed a locking circuit for itself from.- battery through relay 84, springs 83, springs 88, springs 89, and springs and 91 to ground. This circuit is opened by magnet 85 at springs 88. Now if the first trunk line is busy, ground at wiper 80 passes through springs 92, springs 88, springs 83, and relay 84, again energizing relay 84 and again energizing n'iagnet This operation continues until an idle trunk line is found, at which time no ground is present at wiper 80 and relay 81 will not find ground. when 85 falls back. At this time, relay :93, which has heretofore been shorted out, energizes over a circuit from ground through springs 75 and 76, relay 93, springs 88, springs 83, and relay 84 to battery. Relay 93 being of high resistance, energizes but does not allow relay 84; to energize. Relay 93, upon energizing, disconnects the relay .69 from the control of line relay 60 and connects the slow relay 94; in place thereof through springs 95 and 96, closes the line circuit at springs 97, disconnects the relay 98 from the line circuit, and connects the lower wind ing of polarized relay 77 in series with. resistance 99, across the line circuit through springs 100 and 101 and springs 102 and 103. Relay 93 also connects the private wiper ,80 through springs 104 to the hold ing circuit of relay 93. As soon as relay 93 energizes line relay 105 of the connector switch E (Fig. 5) energizes over a circuit from ground through its lower winding, springs 106 and 107, wiper 7 9, springs 97, winding of the repeating coil, springs 102 i and 103, lower winding of relay 77, resistance 99, springs 100 and 101, upper winding of the repeating coil, springs 108, wiper 78, springs 109 and 110, and upper winding of relay 105 to battery. Relay 105 in turn closes a circuit for relay 106, which supplies, ground through springs 112, 113, and 111 to the release trunk and also prepares a circuit for relay 115 and vertical magnet 116 in series.

Each time the line relay 60 is deenergized in response to the next series of impulses, the springs 108 are allowed to open their contacts to repeat the impulses to relay 105. At the same time relay 60 closes a circuit from ground through back contact of spring 70, front contacts of relay 74, springs 96 and 95, and relay 94 to battery. Relay 94c closes a more direct impulsing circuit for the line relay 105 through the springs 117 so that the winding of relay 77 and resistance 99 are not included therein. Relay 105 of the connector now controls magnet 116 to step the wipers 118, 119 and 120 to some level of the bank in the usual manner. Relay 115 upon falling back prepares the circuitof rotary magnet 121 and slow relay 122 in multiple, the off normal contacts 0 N having operated to close their alternate contacts in the meanwhile.

The next operation of relay 105, therefore, through the medium of line relay 60, closes this circuit of magnet 121 and relay 122, and magnet 121 is operated a predetermined number of steps to put the wipers 118, 119 and 120 into connection with the called subscribers line. If the called line be busy then before relay 122 falls back, a circuit is closed from ground on the private wiper through front contacts of relay 122 and busy relay 123 to battery. Relay 123 applies busy tone to the calling line in the usual manner. If the called line is idle then as soon as relay 122 falls back a circuit is closed for the cut off relay of the called mans line switch, through wiper 120, back contact of relay 122, lower winding. of relay 124, and ground at relay 106. Relay 1'24; operates to cut the line circuit through to the called man and locks itself through its upper winding. The called subscriber is then signalled in the usual manner by ringing machine R and when the called man answers, relay 1-25 energizes to cut off the signalling current and connect the called line to the windings of back bridge relay 126. Relay 126 now energizes in series with the called line and reverses the connections of the line relay 105 with regard to the line conductors, thereby reversing the direction of the current flow in the lower winding of relay 77 of the repeater F. Relay 7 7 being electro-pola-r'i-zed now energizes for the first ti-me,.as currents in both windings now assist each other. The results of the energization of relay 77 are as follows: A circuit is closed for the lower winding of relay 60 to hold it energized, the conductor 55 is switched from the upper winding relay 60 to the upper winding of relay 127. By this operation the conductor 55 is switched from ground to battery at the repeater F and therefore the relay 15 which is also connected to battery at the other end of conductor 51 is deenergized and closes the springs 64. When springs 64 close a circuit is completed for relay 4.4 which energizes to reverse the connections of the line relay 40 with regard to the calling line. This reversal of current may be used to operate a meter when the call is from a subscribers line direct or may give supervision to an operator in case the switch E had been seized by an operator, as will be pointed out more fully hereinafter. It will be seen thatthis reversal of current is relayed or repeated on from the called to the calling end of the trunk line over the composite circuit. The two subscribers may now converse over the heavy conductors shown.

Should the calling subscriber hang up his receiver first, the line relay 4-0 of the repeater E deencrgizes and allows relay ail to deenergize. Relay l1 removes ground from the holding circuits of the switches C and D which release in the usual manner. Also relay 4:1 switches the conductor 51, which was formerly connected through relay 4:) to battery, through the back contact of s .n.'ing l6 and springs 1:38 and 129 to ground through upper winding of relays 130. Re lays 130 and 127 energize over this circuit. llclay 127 of selector repeater F upon energizing, opens the contact of springs 72 and T3 in the circuit of relay 74 which relay Tl falls back and closes the circuit of release magnet 131 which releases the switch and opens the off normal springs. Relay '77 will of course fall back as soon as the wipers leave their contacts and relay 60 is therefore again connected to the conductor in series with relay 130 of the repeater E. Relays 130 and (30 being both grounded, relay 130 falls back and relay will not energize. The deenergization of relay 130 of the re peater E results in the restoration of the associated circuits to their normal condition. \Vhen the called man hangs up the connector H will he released. In case the called man hangs up first, the circuits are restored to the condition existing just prior to the answering of the called inan except that the ring cutoif relay 125 of the connector H of course remains locked up. In this case, when the calling subscriber hangs up his receiver, line relay at) of the repeater E falls back and opens the circuit of the line relay 60 of the repeater F, which in turn falls back and opens the circuit of line relay 105 of the connector H. The release of the switches C and D, Fig. 1, and the restoration to normal of the circuits of the repeater l take place responsive to the deenergization ol line relay at), and the release of the switches F and It takes place responsive to the deenergization oi the relays (30 and 105.

It will thus he seen that the impulsing. releasing and reversal of battery for supervision are all controlled over the single conductor including conductor 51 at one end and at the other.

As the trunk circuit shown is two way, I will now describe the operation of the invention when a subscriber in the exchange with B operates a selector to seize the normals 200, 201 and 202 of the selector repeater F to call some subscriber in the e):- ehange with A.

When a selector such as D (Fig. 1) seizes the contacts associated with the normals 200, Jill and 202 a preliminary giouiul is supplied to conductor 302 from the selcclor as usual which flows through the high resistauce upper winding of the flltltjtl'fllltlltll' ized relay 7'? to battery. energize at this time owing to the high re sistance o'l its upper winding. As soon as the line is rut through by the selector, the relay 951 is energized in series with the calling line circuit and operates lo energize relay filo-l: through synxings 205 and fillil. and to close springs 120T. .llelay ill -t connects ground through springs ride and L 'l. oil normal springs 210, spring 76 and its back emiiart. and laacl; tocoutluctor1102 thus supplyii a holding ground to the selector or other switches used to seize the selector rcpeater; prepares a circuit for relay 9-1 at springs-1 211, and switches conductor 55 from the upper winding of relay (i to the lower winding of relay 1 27 through spring .30 and its front contact, lower winding of said relay, springs 20?, and resistance 2.12 to battery.

'lhe impulsing circuit may now be traced from spring :36 over conductor 55, coil 54-,

lrunl: coinluctoi. all, coil 55?, coiiductor 5.1. spring it; and its back eontiuzt. sprin s lilo and 129, and upper winding of relay l lll lo ground. Relays 130 and 12? are energized oi'er this circuit and relay 1?? at armature 233 opens the circuit of reversing relay Lat which circuit was initiall rloered upon the application of the ground potential to conductor 202 by the seizing selector through armature 7e and its back contact, oll' nornial contacts 210, upper contacts of relay tit, and the back contact and armature 2 53, thereby preventing relay 203 .llOll'l operating at this time. ielay 1 -50 upon energizing closes a cirruit from ground through spring (32 and its back conlact, springs 212i and 21% and relay 215 to battery. l'tclay 215 energizes to ground the private contact in the bane: oi selectors such as I) through spring ll and its front contact. 'ri iunds llalngl'i resistance polarizing winding ol' the coil 216, prepares a cirruil tor s ow relay ill. and closes a. bridge arrows the conductors and 21.1w whi h will in this case lead to aselector such as shown at T). Fig. l. The line relay of this selector will therefore he energized as was the line relay 1-lol' selector 1) except that the energizing circuit. instead of p: sing through a suhscrihens line circuit. will in this case pass from conductor 21?, through springs 220 of relay 130, upper winding of the repeating coil, springs .221 and resistance 223, upper winding ol, relay 216, springs 21 and 325. lower wind ing of the repeating co airings 220 of relay 215, and springs bail: to conductor 218.

l'ihcn the tailing subscriber now operates his dial tor the next digit the circuit of relay 98 at the selector repeater l is broken .llclay 'TT does not till ill)

a nuuiler times. Each time relay d8- energizcs it opens the springs 207 and also operates spring 205 to close the circult of relay 94c which rem'ainsenergized during the series of impulses. Relay 94; opens a point in the circuit of reversing relay 2 023, and also closes a short circuitaround the winding of relay 127 in the dialing circuit thus causing the impulses to passthrough springs ?,springs 2 28 and spring 56 and its front contact thus cutting down the resistance in the dialing circuit to relay 130. Each time springs 207 separate, relay 130 at the re )eater E falls back and in the same manner lieeps relay 49 energized during the transmission of impulses, over the circuit prepared by relay 215. Relay 49 closes a short circuit about the upper winding of relay 216 and resistance 223 in series with the line relay of the selector being operated so that each time relay 130 deenergizes the line relay oi said selector is controlledover a circuit from conductor 21 7through springs 220, springs 229, springs 227, andronductor 218.

The line relay of the selector will therefore be operated to seize aconnector such as that shown at H which will in turn be operated iii the same manner to seize the line of a called subscriber. It will be understood that any desired switches lnay beconnected to conductors 217 and 218, depending upon the size of the exchange.- When the called subscriber answers afterbeing signalled a back bridge relay such as 126, Fig. 5, will be operated to reverse the current How in conductors 2 17 and 218 and therefore through the upper winding of relay 216, which will energize with both its windings assisting each other. Relay 216 closes a circuit from ground through springs 230, and lower winding of relay 232 to battery. .l" lay upon energizing switches the con d ctor 51 ot' the inipulsing circuit from the winding of relay 130 and ground, through the winding of relay to battery.

As the inipulsing circuit is now connected to battery at both ends as in the case of the :all previously describetjl, neither of the relays or 127 will be energized no Y and although relay 130 is cut oil from its original energizing circuit, it is held energizedfrom ground through springs 231 of relay 216 and lower winding of said relay 130. Relay 12? upon dee-nergizing closes the springs 233 in the circuit of reversing relay 203. Relay 203 upon eiiergizing, reverses the connections oi the line or repeating relay98 with regard to line conductors 2 00 and 2011, thereby reversing thedirection of current flow therein.

Conversation may now be carried on over the heavy conductors shown. Should the calling subscriber restore his receiver first, the energizing circuit of relay 98 will be broken and "this relay 98 will open the springs 207 and also open the circuit of relay 20-3! Relay 204-, upon lee Zl opens the circuit of relay 203 and of upper winding of relay 77, and closes springs and 57,

the iinpulsing circuit is thereby connected through springs 530 and 57 and springs 58 arr-11130 through relay 60 to ground.

Theopeni'ng of springs 208 and 209 of relay 20a reinoyes ground from conductor 202 and allows the release of the switches held thereover. Relays 00 and 45 now encrgize over the iinpulsing circuit. Relay 45 of repeater-E upon energizing opens the springs 23 inthe circuit of lower holding winding of relay 130. Relay 130, upendeenergizing, opens the springs 220 which control the bridge across conductors 2.17 and 218. hen this bridge is opened the switches eontrolled'thercoyer willreleasc and relay 210 will release and restore all relays to norn' al.

Now suppose the called subscriber is the firSl' ,to restore his receiver when conversation is completed, then the back bridge relay otthe connector switch will be deenergized to restore the current to normal in the lower winding of relay 210 cit-repeater E spring .30, also restores relay 22to again include relay 130 in place of relay 15 in the ilnpulsing circuit. Now when the calling subscriber hangs up the connection isentirely restored to normal by deenergization of relay '08andthe resultant deenergization of relay 20 1, which in this case connects con ductor to relay and ground, there-by deenergizingrelay 130 of repeatcrE and opening the bridge of conductors 217 and 218 at springs 220. It willtherei'ore be seen that a connection may be extended in either direction over the superimposed circuit which includes the talking conductors oi one side of the two trunk lines X and Y (Fig. 3) and that the connection either way is set up over the impulsing circuit including the conductors 5 1, 53 and 55 of one of said trunk lines. Also this conductor is used for controlling the release of the connection by switching said conductor either toground or battery at either end and also for supervisionor metering in the same manner.

Having explained fully the process of establishing connection when the calling suh. scribers are automatic subscribers, I will now point outbriefly how one of the lines termiiiatingat the operators position is cxtended to a called line.

Supposing that the subscriber at substation A, Fig. 6, wishes to obtain connection with the subscriber at substation B, Fig. 5, when the receiver is removed to initiate the call,thejline relay 30l is energized, lighting the line lamp L. The operator responds by plugging into the'jack J witl the answering plug of an idle oneof her cord circuits, cord circuit 0, for example, and then 0136):

ates her listening hey K in order to converse with the calling subseribenand find out what number he wants.

lVhen the plug is inserted in the jack the sleeve relay 303 and the cut oil relay 302 are energized in series, and the latter relay disconnects line relay 301 to put out the line lamp. Relay 5303, upon energizing, closes a point in the circuits of lamps L and L but neither lamp is lighted at this time. The circuit of lamp L is open at a contact of relay 301, which has just been energized orer the calling line, while the circuit of lamp If is open at a contact of the polar relay 306.

As soon as the operator obtains the necessary information as to the desired number she will plug into an idle outgoing trunk jack, jack J, for example, with the calling plug of cord circuit 0, and will operate the *alling device key K. By these operations the connection is extended to the trunk line which terminates in the selector D and the calling device S is connected in bridge of the two line conductors of the trunk line. Accordingly the line and release relays 320 and 1-321 are energized and the selector is prepared for operation in the usual manner.

The operator will now manipulate her calling device in accordance with the first digit of the desired number, whereupon so lector D is operated as was described in connection with the selector D, Fig. l, to establish connection with the trunk line extending to and terminating in the repeater E, Fig. 2. Succeeding operations of the calling device in accordance with the remaining digits now serve to control the repeater E, the selector repeater F, Fig. l, and the connector H, Fig. 5, to complete the connection to the line of substation B. \Vhen the last digit is called the operator will re store the key K. By this operation the polar relay 30b is substituted for the call ing device S in bridge of the trunk line extending to the selector D, and the said rclay is accordingly energized in series with the line relay l t) of repeater E. The direction of current flow at this time is such that the armature of relay 300 is actuated to close the circuit of lamp If and the lamp is lighted.

The operation of the apparatus shown in Figs. 2, 4, and 5 has been fully set forth be fore and it will therefore be unnecessary to again go into these operations in detail. It will be sutlicientto point out that when the called subscriber answers, conductor 55, Figs. 3 and 4, is switched from ground to battery at selector repeater F, causing relay to of the repeater E to fall back. Upon deenergizing, relay 45 closes a circuit for the reversing relay 44: at springs 64, and relay 4-4, upon energizing, transposes the incoming trunk conductors as regards their conneo tions to the windings oi? the line relay :lil. The direction of current flow in the winding of the polar relay Slit) at the cord circuit (J is accordingly reversed and the polar relay armature operated to open the circuit: of lamp L. This extinguishes the lamp and indicates to the operator that the called subscriber has answered.

The required connection has now been established and conversation may proceed an usual. hen the subscribers are through talking they will replace their reci .-i\'ers and disconnect signals will be given to the operator by the lighting of lamps L and L". The circuit of lamp L is closed by relay 304. on deenergizing, while the circuit of lamp L is closed by polar relay 3 )6 responsive to the reversal of the direction of current flow in its winding back to normal. Vhen the operator perceives the d isconnect signals she will pull down the connection. lly this operation the polar relay 306 is disconnected from in bridge oi. the outgoing trunk and the circuit of the line relay 40 of the repeater I) is broken, the same as was described in the case of the connection which was established by the subscriljier at the automatic substation A. The release of the switcl then t'ol lows exactly as has been prerio r described. It will he understood of course that the op crator can bring about the release of the connection at any time either before or after the called subscriber has replaced his receiver, simply by mirroring the plug from jack J, the release in either case being brought about the same as in an automatic connection.

Haring fully described and ascertained the features and aspects of my invention, what I consider to be new and desire to ha \'e protected by Letters Patent will be pointed out in the appended claims.

lVhat I claim as my invention is:

1. In a telephone system, a. trunk line, an auton'iatic switch in which said trunh' lino terminates at the near end, an operating circuit for said switch superimposed on said trunk line and normally connected to the same pole of battery at both ends. means for tempo 'arily connecting said circuit at the distant end thereof to the opposite pole of battery to operate said switch, i'ueans loalso connecting said circuit at. the near end thereof to the opposite pole ol' battrry after said switch has been operated, and release nicans in said switch res onsi e. when th said circuit is restored to normal condition at the distant end.

2. In a telephone system, a pair of trunk lines, a phantom circuit superimposial on the conductors of said trunk lines, a composite circuit superimposed on a conductor of one of said trunk lines, a switch at each end of said phantom circuit for extend ing connections therefrom, a relay in each end of said composite circuit connected to the same pole of battery, means for connecting either end of said-composite circuit to the opposite pole of battery to control the relay on the opposite end to operate its associated switch, and means for switching said opposite end to the other pole of battery when a called subscriber answers.

3. In a telephone system, a pair of trunk lines, a phantom circuit superimposed on the conductors of said trunk lines, an automatic switch at each end of said circuit for extending connections theretrom to called subscribers,

a common operating circuit for said switch normally grounded at each end through an operating magnet ot' the associated switch, means for connecting either end of said cir-- cuit to battery to control the switch at the opposite end thereof to extend a connection to a called subscriber, means controlled by the called subscriber "for switching said circuit to battery at the said opposite end to reverse the battery current in the calling line, and means controlled by the calling subscriber for connecting said circuit to ground again at the near end to again cause a How of current in said circuit to release the switch at the opposite end thereof.

, at. In a telephone system, a two-way trunk line having a switch at each end thereof for extending connections therefrom to called lines, a common operating circuit for said switches, means for causing current to flow in one direction over said circuit to operate one of said switches, and in the other direction to operate the other switch, means for cutting cit the flow of current in said circuit when a called subscriber answers, and means for causing current to flow in a direction opposite to that used to operate a switch. to release the same. i

5. In a telephone system, a two-way trunk line, having a selector repeater at one end and a repeater at the other, means for seizing either end of said trunk line and transmitting impulses over two sidesthercof in series, and means in the seized end for repeating said impulses over a single conductor tothe opposite end thereof to GX- tend a connection therefrom, and means controlled by the response of a called subber for controlling said conductor to rese the How of current in the seized end of said trunk, and means for causing a flow of :urrent over said conductor in the opposite (lllQCtlOlfi to that used to extend the connection, to release the coui'iection.

(S. In a telephone system, a phantom talking circuit supra-imposed on two physical talking circuits between two exchanges, a composite circuit superiniposed on one of said physical circuits, means at either end of said phantom circuit for receiving two wire impulses and, repeating the same over one leg of said composite circuit, and means at eitherend responsive to impulses over said composite circuit to operate switches over llVO sides of a trunk line in series to complete a talking connection from said phantom.

7. In a telephone system, a phantom circuit between two exchanges, a composite operating circuit superimposed on one of the physicals of said phantom over which connections may be extended from said phantom in either direction, and means controlled solely over said composite circuit for operating and releasing two wire switches in either exchange, for reversing the battery to a calling subscriber, and for controlling the superrision of an operator in case an operator is extending the connection,

8. In a telephone system, a trunk line connecting two exchanges, a switch control circuit including a conductor of said trunk line, means whereby a calling subscriber in one exchange can insert a battery in said circuit to cause a flow of current therein, means for then interrupting the circuit, automatic switches in the second exchange responsive to the interruptions for connecting with acalled line, and means operated when the *alled subscriber answers for inserting a second battery in said circuit in opposition to said first battery,thereby stop: ping the fi-ow of current during conversation.

9., In a telephone system, a trunk line connecting two exchanges, a switch control circuit including a conductor of said trunk line, means whereby a calling subscriber in one exchange can insert battery in said circuit to cause a flow of current therein, means for then interrupting the circuit, automatic switches in the second exchange responsive to the interruptions for connecting with a called line, means operated when the called subscriber answers for inserting a second battery in said circuit in opposition to said first battery, thereby stopping the flow oi current during conversation, means controlled by' the calling subscriber for closing said circuit over a path excluding said first battery to establish a current flow from said second battery, and means responsive to current from said second battery for then causing the release of said switches.

10. In a telephone system, a trunk line, a normally closed switch control circuit including a conductor of said trunk line and a ground return, means whereby a calling subscriber at one end of said trunk can establish a flow of current in said circuit and thereafter produce interruptions therein, automatic switches at the other end of said trunk line responsive to said interruptions for connecting with a called line, and means operated upon the response of the called subscriber for closing said circuit over a new path to prevent the flow of current therein during. conversation.

11. In a telephonesystem, a trunk line, a

normally closed switch control circuit in cluding a conductor of said trunk line and a ground return, means whereby a calling subscriber at one end of said trunk can establish a flow of current in said circuit and thereafter produce interruptions therein, automatic switches at the other end of said trunk line responsive to said interruptions for cnnecting with a called line, means operated upon the response of the called subscriber for closing said circuit over a new path to prevent the flow of current therein during conversation, and means responsive to the restoration ot said circuit to normal condition at the calling subscribers end of the trunk for releasing said switches.

12. In a telephone system, two exchanges and an interconnecting trunk line, means whereby a calling subscriber in the first exchange can establish a current flow over a normally closed switch control circuit superimposed on said trunk line, automatic switches in the second exchange responsive to interruptions produced in said circuit for extending a connection to a called line, means operated upon the response of the called subscriber for preventing the flow of current over said closed control circuit during conversation, and a relay held energized over the called line to prevent the release of said switches after the current flow over said control circuit has ceased.

13. In a telephone system, two exchanges and an interconnecting trunk line, means whereby a calling subscriber in the first exchange can establish a current flow over a normally closed switch control circuit superimposed on said trunk line, automatic switches in the second exchange responsive to interruptions produced in said circuit for extending a connection to a called line, means operated upon the response of the called subscriber for preventing the flow of current over said closed control circuit during conversation, the current flow being reestablished when the called subscriber hangs up, and means controlled by the calling subscriber for releasing said switches.

ll. In a telephone system, two exchanges and an interconnecting trunk line, means whereby a calling subscriber in the lirsl exchange can establish a current flow oi er a normally closed switch control circuit HillNllHilWHttl on said trunk line, automatic switches in the second exchange responsive to interruptions produced in said circuit for c zicnding a connection to it called line, means operated upon the response of the called subscriber for preventing the flow of current over said closed control circuit during conversation, and means operable by the calling subscriber before the called subscriber hangs up for again setting up a current low over said closed control circuit to lelease the said switches.

15. In a telephone system, two exchanges and an interconnecting trunk line, means whereby a calling subscriber in the first exchange can establish a current flow over a norn'ially closed switch coi'itrol circuit in cluding the conductor of said trunk line and a ground return, automatic switches in the second exchange responsive to interruptions produced in said circuit for extending a connection to a called line, means in the second exchange controlled by the called subscriber tor stopping the flow of current in said closed control circuit during conversation, means controlled by the called subscriber for preventing the release of said switches responsive to the cessation of current flow in said control circuit, means in the first exchange controlled by the calling subscriber for reestablishing a current flow in said closed control circuit before the called subscriber hangs up, and means in the second exchange responsive to the reestablished current flow for releasing said switches.

16 In a telephone system two exchanges and an interconnecting trunk line, means whereby an operator in one excl'iangc can connect with said trunk line and establish a current flow over a normally closed switch control circuit superimposed on said trunk line, means for then momentarily interrupt ing the circuit at the first exchange, auto matic switches at the second exchange responsive to the interruptions for connecting with :1 called line, and means operated upon the response of the called subscriber for stopping the current flow in said control circuit to give the operator :1 siuiervisory signal.

17. In a telephone system, two excl'u'ingcs and an interconnecting trunk line, means whereby an operator in one exchange can connect with said trunk line and estaljilish a current flow over a superimposed switch control circuit including one conductor of said trunk line and a ground return, means for then mon'ientarily interrupting the circuit at the first exchange, automatic switches at the second exchange responsive to the interruptions for connecting with a called line, means operated upon the response of the callcd subscril'ier for preventing the flow ot cur rent over the control circuit during convcrsation, means responsive to the cessation ot the current flow for giving the opcraf'or a supcrvisory signal. and a relay hcld cncrgized over the called line to prevent the release of said switches: after the current flow over said control circuit has ceased.

18. In a telephone system, two exchanges and an interconnecting trunk line. means whereby an operator in one exchange can connect with said trunk line and establish a current flow over a normally closed switch control circuit superimposed on said trunk line, means for then momentarily interrupting the circuit at the first exchange, automatic switches at the second exchange recircuit including a conductor of said trunk line, a manual switchboard in the first exchange, means whereby an operator at said switchboard can insert a battery in said circuit to cause a How of current therein, operator controlled means for then interrupting said circuit, automatic switches in the second exchange responsive to the interruptions for connecting with a called line, means oper- ,ated when the called subscriber answers for inserting a second battery in said circuit in opposition to said first battery, thereby stopping the flow of current during conversation, and means responsive to the cessation of current flow for giving the operator a supervisory signal.

20. In a telephone system, a trunk line connecting two exchanges, a switch control circuit including a conductor of said trunk line, a manual switchboard in the first exchange, means whereby an operator at said switchboard can insert a battery in said circuit to cause a flow of current therein, operator controlled means for then interrupting said circuit, automatic switches in the second exchange responsive to the interruptions for connecting with a called line, means operated when the called subscriber answers for inserting a second battery in said circuit in opposition to said first battery, thereby stopping the fiow of current during conversation, means responsive to the cessation of current flow for giving the operator a superviso'ry signal, operator controlled means for closing said circuit over a path excluding said first battery to cause a current flow from said second battery, and means responsive to current from said second battery for causing the release of said switches.

21. In a telephone system, two exchanges and an interconnecting trunk lead, automatic switches in the second exchange controlled from the first exchange forestablishing a talking connection over said trunk line, the release of said switches after the connection is established being also controlled from the first exchange, first and second batteries in said first and second exchanges, respectively, means for supplying current to said trunk line from said first battery for controlling the operation of said switches, means for connecting the second battery when the connection is established, both batteries be ing connected to the trunk in opposition during conversation, and means for cutting out the first battery to cause a current flow from the second battery and release the connection.

22. In a telephone system, an automatic switch, a trunk line over which said switch may be controlled to operate and release the same, a grounded battery at each end of said trunk, suitable circuits for connecting the ungrounded poles of said batteries to the trunk, the arrangement being such that whenever both batteries are connected to the trunk at the same time they are in opposition, and relays for closing said circuits at proper times to supply current from one of said batteries to said trunk for controllingthe operation of said switch, and to supply current from the other of said batteries to said trunk to control the release of said switch.

23. In a telephone system, a trunk line and a train of automatic switches for use by an operator in extending a connection to a called line, a supervisory signal, a com bination supervisory and switch control circuit including a conductor of said trunk line, a batteryiincluded in said circuit at the operators end of the trunk line for supplyingcurrent to set said switches, a second battery at the other end of the trunk inserted insaid circuit in opposition tosaid first battery when the called party responds, and means responsive to the resulting cessation of current fiow in said circuit for c011- trolling said, signal.

24. In a telephone system, a trunk circuit for connecting a calling and called line, an automatic switch at the called end of said trunk circuit for connecting with the called line, a device at the calling end of said trunk line responsive to the answering of the called party, a battery at the calling end of said trunkline for supplying current over the trunk line to control the setting of said switch, a second battery at the called end of said trunk line substantially equal in voltage tosaid first battery, means controlled by the called party for connecting said second battery in opposition to said first battery to substantially prevent current flow over the trunk line from either battery, and means responsive to the cessation of current flow for controlling said device aS set forth.

25. In a telephonesystem, two exchanges and an interconnecting trunk line, a switch control circuit, means in the first exchange for connecting with said trunk'line and-for establishing a flow of current in said circuit, means at the first exchange for then producing momentary interruptions in the current flow, automatic switches at the second exchange responsive to the interruptions for extending the trunk line to :1 called line, means controlled by the called party when he answers for stopping the flow of current in said circuit, and a supervisory relay in the first exchange responsive to the cessation of current flow in said cireiut.

26. In a telephone system, two exchanges and an interconnecting trunk line, a switch control circuit, means in the first exchange for connecting with said trunk line and for establishing a flow of current in said circuit. means at the first exchange for then producing momentary interruptions in the current flow, automatic switches at the second exchange responsive to the interruptions for extending the trunk line to a called line, means controlled by the called party when he answers for stopping the flow of current in said circuit, a relay in the first exchange for controlling a supervisory signal, and means responsive to the cessation of current flow in said circuit for operating said relay.

27. In a telephone system. two exchanges and an interconnecting trunk line, a switch control circuit, means in the first exchange for connecting with said trunk line and for establishing a flow of current in said circuit, means at the first exchange for then producing momentary interruptions in the current flow, automatic switches at the second ex change responsive to the interruptions for extending the trunk line to a called line, means controlled by the called party when he answers for stopping the flow of current in said circuit, a supervisory relay in the first exchange responsive to the cessation of current flow in said circuit, means in the first exchange for re-establishing the flow of current in said circuit, and means responsive to the renewed current flow for re leasing the connection.

29. In a telephone system, a circuit, means at one end of said circuit for setting up a. flow of current therein and for subsequently producing momentary interruptions in the current flow, a switch at the distant end operated responsive to such interruptions, means at the distant end for stopping the flow of current in said circuit while maintaining the switch in operated position, signal controlling means at the near end responsive to the cessation of current flow, and means at the near end for again establishing the flow of current to release said switch.

29. In a telephone system, an automatic switch, means including a control circuit for said switch for operating the same to conneet with a called line, and releasing means for said switch responsive either to the es tablishmcnt or the cessation of: current flow in said circuit depending on whether the called line is in answered or unair wcred -on dition.

30. In a telephone system, a trunk line terminating in an impulre repeater. a firs-z closed circuit including a conductor oi said trunk line and a source of current, a rcii-ond closed circuit including, a source oi current and extending from said repeater to a tant point, said repeater being res mna' to a series of interruptions in the current flow in said first closed circuit to producia series of interruptions in said second clot-red circuit, means at said distant point lor stopping the current flow ove said second closed circuit, and means in said repeater responsive to such cessation of current flow for reversing the direction of current flow in said first closed circuit.

31. In a telephone system, a trunk line extending to an automatic impul e i'cpcnlrl, a closed circuit including said trunl: line and a source of current, a second closed circuit including a source of currentand extending from said repeater to a distant point, said repeater being responsive to control over said first circuit to produce interruptions in the current flow in said second closed circuit, means at said distant point for interrupting the current flow over the associated closed circuit, and means in said repeater responsive to such cessation of currentllow for reversing the direction of current flow in the first named closed circuit.

In a telephone system, an impulse repeater for producing a series of interruptions in the current flow through a closed circuit. means outside of: said repeater for llllCllllPtlllg the current flow in said closed circuit, a trunk circuit incoming to said repeater, a relay for exercising a control over said trunk circuit, said relay bcimg operated responsive to said outside intcn ruption, and a slow acting relay in said repeater energized during the production ot said series of interruptions to prevent the said operation oil said relay.

3-). In a telephone system, an impulse rcpeatcr For n'oducing a series of interruptions in the current flow through a closed circuit, means outside of said repeater for interrupting the said current flow. a supervisory relay in said. repeater operated rcsponsive to said outside interruptirm, and a slow acting relay in said repeater energized during the production of the series of intcrruptions in the said closed circuit to prevent the said operation of said supervisory relay from taking place at such time.

34. In a telephone systen'l, a trunk line terminating in an impulse repeater, a control relay in said repeater for controlling the current flow in said trunlc line. means for extending a connection to said trunl: line and for closing a circuit tor said control relay. a conductor extending from said rcpeater to a distant point. means responsive to the said extension ol' the connci'rtion for setting up a current How ever said conill) ductor, a second relay in said repeater responsive to such current flow for opening the circuit of said control relay before the J device, a circuit for said device, a trunk circuit, means for closing said circuits at substantially the same time, a relay energized over said trunk circuit to prevent said device from operating, and means at the distant end of said trunk circuit for stopping the flow of current therein to deenergize said relay, whereby said device is operated.

In a telephone system, a control circuit extending to a distant point, means at the near end of said circuit for setting up a current flow thereover, means at the distant end for stopping the current flow, a device at the near end responsive to such cessation of current flow, means at the near end for producing a series of interruptions in the current flow prior to the operation of said means at the distant end, and means for preventing said device from responding to such series. A

Signed by me at Chicago, Cook County, State of Illinois, this 19th day of October, 1918.

JOHN WICKS.

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