US1352217A - Selective signaling system - Google Patents

Description

w. T. POWELL. SELECTIVE SIGNALING-SYSTEM.

APPLICATION FILED AUG.23, I916. 1,352,217 PatentedSept. 7, 1920;

2 SHEETS-SHEET l.

222152-2227? W r Q,

H ZZUFHE W. T. POWELL.

I SELECTIVE SIGNALING SYSTEM.

' APPLICATION FILED AUG-23, 1916.

1,352,217,, Y PatentedSept. 7, 1920.

2 SHEETS SHEET 2.

UNITED STATES PATENT OFFICE. v

WINFRED "1. POWELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SELECTIVE SIGNALING SYSTEM.

Specification of Letters Patent. I Patented Sept. '7, 1920.

Application filed August 23, 1916. Serial No. 116.481.

To all whom it may concern: 7

Be it known that I, WINFRED T. POWELL, a citizen of the United States of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Selective Signaling Systems, of which the following is a specification. 4 g

My invention relates in general to selective signaling systems, but is concerned more particularly with selective signaling in automatic telephone systems, in which connections are established through the medium of directively controlled selector and connectorswitches.

The principal object is to provide in a system of the above general character means for. selecting the proper ringing current at the last selector. switch just preceding the final selector or connector, thereby rendering possible the use of a single group of connectors for selectively calling the subscribers on a party line. i

Inventions along this line have been disclosed before, notably in the recently issued patent to Deakin, #1,185,635, but to the best of my present knowledge all previous attempts have involved the multiplying of the selector levels. For example, in the above mentioned patent to Deakin, each connector group is accessible to calling lines by way of as many selector levels as there are stations on' a line.

In my improved system I provide a single group of connector switches for selectively calling each group of party lines and assign to each connector group a single selector level, therebyrobtaining a great economy in apparatus. his arrangement is made possible through the use of a new method of ringing current selection in which the proper ringing current is picked out by a preliminary operation of the selector switch.

The particular means and circuit arrangement by which the foregoing and other useful ends are accomplished will be fully described hereinafter, reference'being had to the accompanying drawings, which show diagrammatically a complete circuit connection between a calling substation A (Figure 1) and a called substation A (Fig. 2). The exchange equipment used in setting up the complete connection shown comprises the individual line switch 0, the selector E, and the connector F.

Referring now to Fi 1, the substation A may be of any suitab e type or construction, such, for example, as the type disclosed in British patent to T. G. Martin, No. 1419 of 1910. As shown herein it comprises essentially the receiver 2, transmitter 3, switch hook 4-,ringer 5 and condenser 6. Being an automatic substation there is also provided a pair of impulse springs 7 and 8 controlled by the impulse wheel 9 through the medium of a finger hole dial (not shown). I

The line conductors 12 and 13 of the substation A are connected at the exchange to the individual line switch C which may be of the general type of line switch disclosed in ritish patent to R. V. James, No. 26,301 of 1906; being, h0wever,.of the particular type shown in United States Letters Patent No. 1,078,690 granted Jan.

17, 1912, to Frank Newfprt Since line switches of the above type are well known and form no part of my invention an ex tended description will not be given. It will suffice to say here that through the medium of line switch C the line of substation A,'when calling, is given access to a plurality of selector switches, one of which is shown at the right of Fig. 1 and is indicated by reference'character E.

The master switch D is of the general type of master switch disclosed in the above mentioned British patent to James, No. 26,301 of 1906; being, however, more nearly of the particular type disclosed in the Brit- -ish patent to Martin, No. 1419 of 1910. As

is well understood, the function of the master switch is to maintain the plungers of all the idle line switches which it controls in position before the terminals of an idle trunk line. I

The selector switch E is of the general type'of selector switch disclosed in U. S. Letters Patent No. 815,321, granted March 13,1906, to Keith, Erickson and Erickson; the side switch and private magnet, how- .ever, being omitted, and the circuits being modified to enable the switch to operate in a system in which the impulses are delivered over the two sides of the line in series.v

Further modifications, supplied in accordioo ance with my invention, have to do with the ringing current selection and will be described later on. A selector switch of theforegoing general type, as is well known,

' 1 group. I

- One of the lines towhlch the connector.

One of the trunk'lines to which the selector E has agcess is indicated in the drawings by the reference characters 120, 121, 122,

and 123 and extends tothe connector switch 'F (Fig. 2), which is of the general t pe of connector switch disclosed in U. S. etters Patent No. 815,176, granted March 13, 1906, to Keith, Erickson and Erickson; being, however, U. S. Letters nector switch of the foregoing type may be given access to a group of one hundred subscribers lines and is operable in response to the two last digits in a called number to establish connection with any line in the F has access is the party line shown in the upper half of Fig. 2 and having the line conductors 12' and 13".

bridge of the line conductors in the usual manner and are similar to the substation A,

which has been described, with ,the excep-' tion, however, that the ringers are adapted to respond to different-frequencies of ringing current. At the exchange theline conductors 12 and 13. terminate in the individual line switch C which is similar to the line switch C (Fig. 1).

The s ecial equipment associated withthe selector and which is concerned with the selection. of ringing current frequencies comprises the relays 40, 41', and 42, which are controlled through the medium. of the usual private wiper 71 and the special wiper 70. These wipers exercise their controllingfunctions through their engagement with the I first sets of contacts in the 7th, 8th, 9th,

of the associated switch. Other special "provisions in the selector E comprise an additional winding 55 on the relay 53, whose pur ose will be explained, and a set of sha t controlled springs 62, which are prof contacts 60 and 61.

vided in-addition to the usual ofl normal I, The springs 62 are closed only on the tenth vertical step.

A' to A, inclusive. The generator R detion wanted, as

of the Iparticular type disclosed in atent No. 13,901, reissued- April 13, 1915, to Frank Newforth. A con-.

The four substa-. tions A, A A and A are connected in The generators R, R R and R deliver ringing currents of different frequency and are adapted to actuate, respectively, the r1ngers105, 205, 305, and 405, at substations livering referably current of a frequency of 33 cyc es per second is normally in serv- I ice, but any one of the other generators maybe selected, de endin on the substa- Will be in ly explained in the detailed descriptions of the operation.

For supplying current for operating. and V talk ng purposes I have shown a battery B, havmgits positive pole ounded. Ass0- mated with the. connector I have shown an interrupter I and a busy signalingmachine Q which are of the usual type and perform the same functions as the samenamed pieces offipparatus in other automatic systems.

avlng given a eneral description of the apparatus involved I will now proceed to an explanation of the operation of the system. F or this purpose it will be assumed t at the subscriber at substation A desires to obtain connection with the subscriber at 90 substation A, this being the complete circuit connection shown in the drawing. Inasmuch as a great deal of the apparatus shown is well'known in the art, having been fully described in the'publications previously referred to, the operation will be described in a more or less general manner, the details being given only in sofar as they are concerned with my invention.

Referring to Fig. 1, when the subscriber at substation A removes his receiver to initiate the call, an energizing circuit is completed over the line conductors 12and 13, for the line relay 16 of the line-switch C. Upon attracting its armature, the line relay 16 closes a circuit forthe pull-in winding 17. Upon energizing, the pull-in winding operates both the plunger arm 21,. and the cut-ofi armature 22; the former through the medium of its plunger (not shown) 11 forcing the bank springs 30-33, inclusive, into engagement, respectively, with contacts 34-4-37, inclusive; and the latterdisconnecting the -'line conductors 12 and 13, respectively, from ground and from the line relay 118 16. By the engagement of bank springs 30 and 33, respectively, with contacts 34 and 37, the line conductors 12 and 13 are extended to the (jlimble wound line relay 50 of theselector The line relay 50 is accordingly energized over the loop. circuit including substation A and, upon attracting its armature, closes a circuit for the slow acting release relay 51. Upon energizing in turn, the relay 51 com- *1!!! pletes a holding circuit for the line switch G which may be traced as-follows: ground at G", contact springs 63 and 64, contact. 35, bank spring 31, and holding winding- 18 to battery B. Since the line relay 16 is 136 [taken place in slow acting, it retains its armature to maintain the pull-in winding 17 energized until after the above holding circuit has been on these test contacts the said line is made busy. By the engagement of bank spring 32 with contact 36 the master switch D is operatedjn well knownmanner to advance the plungers of all the remaining idle line switches into position before the terminal of the next idle trunk line.

The foregoing operations whereby the line conductors 12 and 13 have been extended to the line relay 50 of the selector E have response to the removal of the receiver at substation A. The calling subscriber may now manipulate his dial in accordance with the first digit of the desired number, which digit is to determine the frequency of ringing current to be applied to the called'line by means of a preliminary operation of the selector E, all as previously mentioned. Since it is required that the generator R'be selected, this generator 1 being the one .corresponding to substation A, the first digit of the called number will be the digit 0. When the calling device dial is operated in accordance with this digit the impulse springs 7 and 8 are separated momentarily ten times thereby interrupting a like number of times the energizing circuit of the line relay 50.

At each interruption of its circuit the line relay 50' is deenergized momentarily and sends an impulse from ground through thewinding 54 of the slow acting relay 5'3 and the winding of the vertical magnet 58 in series. The vertical magnet, in response to these impulses, operates to step up the switch shaft until the wipers 70, 71, 72, and 73 arrive at the tenth horizontal level of bank contacts. The relay 53 is energized in series with the vertical magnet and beingslow acting retains its armature during the series of impulses. Upon the first .upward movement of.the shaft the off normal contact 60 is closed thereby completing a circuit for the relay 57 which extends from ground Gr by way of contact springs 63, 64, and 65, the contact springs 66 and 67 of the now energized relay 53 and the off normal contact 60 to the winding of the said relay 57. Upon energizing, the relay 57 locks itself independent of the relay 53 by means of its upper set of contact springs, and by means of its lower set of cuit for the rotary magnet 59 which is held open' during the vertical operation of the switch by the relay 53.- At this point it should be mentioned that by the closure of 56 is short circuited and remains -t1ve for the present.

contact springs prepares a cir rela' 56, whose right hand terminal is joined to t e holding circuit offline switch C and.

is therefore grounded, is connected in series with the relay 57, the circuit passing through the interrupter contact 88 of the rotary magnet. The junction point 89, however, has already been connected to ground G as previously described so that the relay VVhenthe slow acting relay 53. deenergizes pletes by means of its contact springs 66 and 68 the previously mentioned circuit of the rotary magnet, extending from ground G. Upon energizing, the rotary magnet operates to rotate the wipers 70, 71, 72, and 73 inopera at the end of the series of impulses it'comintoengagement with the first set of bank contacts of the tenth horizontal level. Near the end of its stroke the rotary magnet also breaks, at its interrupter contact 87, the locking circuit of relay 57; and at its interrupter contact 88, the circuit of the line switching relay 56. Upon deenergizing, the relay 57 breaks the energizin circuit of the rotary magnet which accordingly retracts its armature to again close the interrupter contacts 87 and 88. The operation now depends on the grounded or non-grounded condition of the test contact with which the private wiper 71 is in engagement. Since the wipers were raised to the tenth horizontal level before rotation the private wiper 71 is now in engagement with bankcontact 81. Current for the energization of relays 40 and 37 in series now flows over the following path: ground at G right hand winding of relay 40, bank contact 81, private wiper 71, contact spring 91 of relay 56 and its resting contact, interrupter contact 88, off normal contact 60, and the winding of relay 57 to battery. B. A branch of the above circuit ma .be traced from ground G by way of the r1ght hand windin of relay 41 and the off normal springs 62 closed on tenth Vertical step) to the junction point 92, where it joins the previously traced circuit. It follows that relays 40 and 41 (in parallel) are energized in series'with relay 57 via the winding of relay 40 to battery B, thereby providing a locking circuit for relay 40. it

should be mentioned here that the right hand windings of relays 40 and 41 are of low resistance so as to prevent the energization of the much higher resistance line switching relay 56, which as previously mentioned is also in series with relay 57.

Upon the reenergization of'relay 57 the usual manner.

rotary magnet circuit is not again com plcted at this time because of the energized condition of relay 53 which was brought about as follows: When the wiper'70 came into engagement with bank contact 85, si-

-multaneously with the engagement of bank contact 81 by wiper 71, a circuit was completed which extended from ground G by way of bank contact 85, wiper 70, contact springs 96 and 97 of relay 12, winding 550i relay 53, off normal contact 61, and the release magnet 52 to battery B. Upon the closure of the above circuit the relay 53 and the release magnet 52 are energized in series, the former preventing the closure of the rotary magnet circuit, as previously mentioned, and the latter operating to restore the selector switch to normal position in the A branch of the circuit com. pleted over wiper may be traced by Way of contact springs 96 and 98and the winding of relay 42 to battery B. Relay 42 is slow to energize (being provided with a copper slug on its core and having a stiff adjustment) inorder to allow time-for the operations just described to take place. Upon finally attracting its armature, relay 42 short circuits the right hand windings of relays 40 and 41 by means of its upper three contact springs and the groundconnection at G; and also brings its contact spring 99 into engagement with contact spring 98, whereby the latter spring is separated from contact springs 96 and 97. A locking circuit forrelay 42 may now be traced over the following path: ground at G conductor 95, .contact'springs 99 and 98, and the winding of relay 42 to battery B.

To sum up the operations brought about in response to the calling of the first digit, the relays 40, 41-, and 12 have been energized and locked to ground G and the selector E has been restored to normal.

Thecalling subscriber may now operate his calling device in accordance with the second digit of the desired number, which for convenience has been assumed to be the digit 1. In response thereto the selector switch'is controlled as before to raise its wipers 7Q, 71, 72, and 73 to the first horizontal level of bank contacts, after which the wipers are rotated into engagement with the first set of bank contacts of the first level. Upon the deenergization of the rotary magnet after the first rotary step, the operation now as before depends upon the grounded or non-grounded condition of the test contact with which the private wiper 71 is in engagement.

Assuming that the trunk line terminating in the first set ofcontacts of the first level is idle, the test contact will not be ground-- ed and consequently there will be no circuit completed for the relay 57 and the line switching relay 56 will no longer be short .circuited. The said switching relay will wiper 71 from itsnormal connection at the winding of relay 56 to the holding circuit at junction point 102; and disconnects the incoming line conductors from the line relay 50 and extends them by way of the line wipers 72 and 73, bank contacts 76 and 77, and conductors 122 and 123 to the double wound line relay 130 of the connector-F.

The line relay 130 is accordingly ener-g gized over the calling subscribers loop, and, upon attracting its armature, completes a circuit for the slow acting release relay 131. Upon energizing in turn, the relay 131 prepares a circuit for the vertical and rotary magnets 132 and 133 in the usual manner and also completes a new holding circuit which may be traced as follows: ground G, contact springs 146 of relay 131, conductor 121, bank contact 75, private wiper 71, contact spring 91 and its working contact to junction point 102, where it joins the previously described holding circuit extending back to the line switch (A A branch of the above circuit extending from junction point by way of the winding of switching relay 56, the interrupter contact- 88, the off normal. contact 60 and the winding of relay 57 to b ttery whereby the said switching relay is maintained energized to prevent the release of the selector the slow acting relay 51 of the selector switch has had time to deenergize.

The calling subscriber may now manipulate his calling device in accordance" with the third digit of the desired number, thereby causing another series of interruptions of his line circuit. Responsive to these interruptions the line relay 130 deenergizes a cor responding number of times and sendseach time an impulse from ground at-Gr to the slow acting relay 139 and the vertical magnet 132 in series, side switch wiper 142 being in its first position. The vertical magnet, in response to these impulses, steps u the shaft until the wipers 160, 161, and 162 stand opposite the horizontal level of bank,

contacts in which the line of substation A terminates. Relay 139, being slow acting,

retains .its armature during the series of impulses and maintains a circuit from At the end of the series of impulses, the

relay 139 deenergizes andbreaks the circuit of the private magnet, which latter controls the side switch wipers in the usual manner to advance them to theirsecond po-.

sition."

- The subscriber at substationfi' ma now .operate his dial in accordance wit the fourth and final digit of the desired number,

resulting as before in deenergizations of the line relay 130. Now, however, side switch wiper 142 being in its second position, the line relay sends impulses tothe slow acting .relay 139in series with the rotary magnet .133.' The rotary magnet operates in responselo these impulses to rotate the wipers 160, 161, and 162- until they rest, respec- I tively, upon bank contacts 163, 164, and 165,

.1 these contacts formingthe terminal of the line of substation A. in the bank of connector'H. The private magnet 138'andthe wiper cut-ofi relay 136 are energized during the final series of impulses asbefore', the latter disconnecting the line wipers during rotation and the former, upon 'deenergizing, controlling the side switch wipers to advance them to their third position, it being assumed that the line of substation A was idle when called. I

As side switch wiper 1 43 comes into en- "gagement with its third position contact point, a circuit is completed for the cut-off lows: ground at G", side switch wiper 143 (in third position), wiper 161, bank contact 164, and winding 18' to battery B. By the closure of the above circuit the cut-ofl armature 22 ,is operated to disconnect the line conductorsj12' and '13, respectively, from ground and from the line relay 16. Ground at Gr also extends to multiples-of bank contact 164 in the banks of other connectors of the group, thereby making the line of substation A busy to other calls. A

By the engagement of the side switch wipers 144 and 145 with their third position contact points the connection between the calling and called substations is completed, relay 136 being denergiz-ed. By the engagement of side switch wiper 142 with its third position contact point, a circuit is completed for the ringing relay 137 in series with the interrupter 1, whereby ringing'current from generator R is projected intermittently out over the line of substation A to operate the signal 105 in bridge thereof. The path for the ringing current may. be traced as follows: ground at G, generator R, contact springs 103 of relay 40, contact springs 104 of relay 41, contact springs 112 of line switching relay 56, wiper'70, bank contact of ringing relay 137, contact springs 107, wiper 160, bank contact 163, the called subscribers line and ,substatlon ringers in bridge thereof, bank contact 165, 'wiper 162, contact'sprlngs 108, and contact springs. 109 to ground at G. As previously mentioned,

the ringer 105 at substation A is the rin er adapted to respond to the particular requ'ency of ringing current delivered by generator R. I

The subscriber at substation A has nowestablished the required connection with the line of substation A and the bell at the latter substation is being rung toattract the attention of the called subscriber. When the called subscriber removes his receiver from the hook a circuit iscompleted for the double wound back brid e relay 141 in the well known manner. 'l pon attracting its armature, relay 141 closes a circuit for the ring cut-ofi" relay 135 which relay locks itself to ground at G and alsoopens the circuit of the ringing relay 137, thereby stopping the ringing operation. As a further result of the 'energization of relay 141 the incom- "ing line conductors 122 and 123 are reversed as regards their connection with the windings of line relay 130. The latter operation is withoutimportance inthe system shown here, although it is provided in case it is desired to operate meters orsim'ilar apparatus. I

The calling and called subscribers. may now converse without further effort. Current for the transmitter at substation A is supplied through the windings of the line relay 130, whilecurrent for the transmitter at substation A .issupplied through the windings of the back bridge relay 141.. The voice currents follow the path shown in the heavy lines which, itis thou ht,'will be apparent without further ampliiying the explanation.

, When the conversation is completed both subscribers willhang up their receivers. By the replacement of the receiver at substation A the circuit of the line relay 130 of the connector F is broken. Upon deenergizing,

relay 130 breaks the circuit of relay 131,

which relay, upon deenergizing in turn, closes; a circuit for the release magnet 140, whereupon the connector F is restored to normal in the usual and well known manner. As a further result of the deenergization of relay 131, ground G is removed from the holding circuit extending back to the selector E and the line switch G] The selector and line switch therefore are also restoredto normal. In addition the relays 40, 41, and 42, whose locking circuits have been supplied with-ground over the holding all the apparatus will have been restored to -normal in readiness for another call. 74, trunk conductor 120, contact springs 106 Y The operation of a connector switch such as connector H when connection is attempted with a busy line is well known and has circuit, retract their armatures whereupon been fully described-in the publications previously mentioned. Since my invention involves nothing new in connection with this feature of the operation the description thereof will be omitted.

Having described the operations incidentto the establishin of a connection with subscriber A, I wil now describe briefly the operation of signaling the Substations -A A and A. Since all the substations mensubstation A requiring the selection of generator R the first digit to be called is the digit 7.. Since the bank contacts 78 and 82 of the seventh level are both permanently grounded, the selector E will be operated and released and the relay42 will be locked up as previously described, but neither of the relays and 41 will be operated. -With boththese relays denergized the generator R is in service, as-will be readily apparent upon tracing the circuit. If substation A is wanted, the first digit called is the digit 8. It will be observed that the right hand winding of relay .41 is connected to the bank contact 79 of the eighth level. Consequently, when the selector E' is operated inresponse to the calling of the diglt 8 and is released as before, the relay 41, in addition to the relay 42, will/be energized. With r'ev .lay 41 energized and relay 40 deenergized,

the generator R corresponding to substation A is in service. Assuming finally that substation A is wanted, the proper digit to be called for the frequency selection is the digit 9. The right hand windingof relay 40 being connected to the bank contact 80- of the ninth level, the said relay i0 is energized to select the generator It will be observed that whether the first digit called is 7, 8, 9, or 0, the relay 42 is operated and locked up inlany case ,with the result that the right hand windings of relays -10 and 41 are short circuited by ground G.

This is donein order to prevent these relays from operating on the second digit of it called number, in case they were left (1e energized after the first digit was called. It would not be 'suflicient merely to open the circuits of theserelays, for the bank contacts 78, 79, 80,- and 81 must have ground potential on them in order to permit the selector E to pass over the first contacts in the seventh, eights, ninth and tenth levels when it is operated in response to the second digit of a called number and the selection of an idle trunk is required. Having described my invention What I consider to be new and desire to have protected by Letters Patent will be pointed out in the a pended claims.

What claim as my invention is: y 1. In a telephone system, means compria. ing a selector and connector switch. for connecting a calling and a called line, together j with means individual to said selector for selectively signaling the stations on the called line controlled in a preliminary operation of the selector switch separate from the trunk selecting operation thereof.

2. In a telephone system, means compris- .ing a selectorand connectorswitch for connecting a'callmg and a called l1ne, togetherwith means individual to said selector for selectively signaling the stations on the called line controlled in a preliminary operation of the selector switch,

tor after the preliminary operation 'thereof and before the connection is completed.

3. In a telephone system, a party line,

means including a selector switch and a connector swltch for extending a connection to said party line, means individualv to said selector for. selectively signaling the. sta

tions onsaid party line, and means for giv and i means for automatically releasing saidselecing said selector apreliminary movement to I determine the character of the signaling 0p-- eration and for then operating said selector to extend the connection.

4..In 'a telephone systenna party line, .7 mearisQmcl'udi'ng a selector switch and 'a connector switch for extending a connection to said party line, means individual to said selector for selectively signaling the stations on said party line, means for giving said selector a preliminary. movement to determine thecharacter of the signaling operation, andmeans for automatically releasing" said; selector after the preliminary movement thereofand com'pletedl 5. In a telephone system, a plurality connector switches, a'.' plurality of ringing current generators, a selector switch, means before the connection is Y J for causing successive operations of said. selector to select'one of said generators and one of said connectors, and means for. automatically releasing said selector between successive operations thereof.

6. In a telephone system, a selector switch and a plurality of connector switches acces sible thereto, a plurality of ringing current generators, and means for operating said selector in response to two digits of a called number to select one of said generators and 'one of said connectors.

7. In a telephone system, a selector switch and a plurality. of connector switches accesgenerators, means for operating said selector 1n response to one digit of a called number to select one of said generators and means j sible thereto, a plurality of ringing .current for'operating said selector-in response to' a succeeding digit of the called number to select one of said connectors.

8. In a telephone system, a selector switch having vertical and rotary motion, groups of connector switches accessible to said selector, said groups selectable in the vertical movement thereof, ringing current generators also selectable in the vertical movement of said selector, and means for causing sue-- cessive vertical movements of said selector to select one of said said connector groups.

9. In a telephone system, a connector switch, a selector switch for extending connection'to said connector, ringing current generators selectable by said selector, and means for causing successive operations of said selector to select'one of said generators and to extend the selected generator to. said connector.

10. Ina telephone system, a plurality of trunk lines each extending to a connector switch, a selector switch having access to said trunk lines, a plurality of ringing cur-- rent generators, and means for causing successlve operations of said selector to select one of said generatorsand to connectthe selected generator to one of said trunk lines.

11. In a telephone system, a connector switch, a'selector switch for extending connection to said connector, ringing current generators selectable by said selector, means for causing successive operations of said selector to select one of said generators and to extend the selected generator to said connector, and means for automatically releasing said selector between successive operations thereof.

12. In a telephone system, a-plurality' of trunk lines each, extending to a "connector switch, a selector switch having access to said trunk lines, a plurality of ringing current generators, means for causing succes- SlVe operatlons of said selector to select one of said generators and to connect the se-- lected generator to one of said trunk lines, and means for automatically releasing said selector between successive operations thereof. v

13. In a selective signaling system, the combination with a plurality of ringing current generatorS,-of means controllable by a calling subscriber for selecting one of said generators, a trunk line common to'aplurality of said means for extending connection to a called line, said means adaptedto select a generator in one operation and to extend a connection to said trunk line in a separate operation, and means for applying a selected generator to the called line via a conductor of said trunk line.

14; In a selective signaling system, four generators arranged in pairs, a relay for selecting either pair, a second relay for segenerators and one of switch, having wipers for use in connectlng lecti-ng either generator of the selected pair,

and means whereby the selected generator is 1 applied to a subscribers line.

15. In a selective signaling system, four generators arranged in pairs, a relay for selectingeither pair, a second relay for selecting either generator of the selected'pair,

means whereby said relays are controlled by, a callingsubscriber, and means whereby the,

selected generator is applied to a called line ,to signal asubscriber thereon.

1T6. In a telephone system, an automatic -'a calling anda called line, a plurality of stations on the called-line; a plurality of ringing current generators .for selectively signaling said stations, and relays controlled 1 in, the movement of said wipers by said switch, said relays provided with means whereby they conjointly accomplish the selection of any oneof said generators.

17. In a telephone system, means ing a plurality of automatic switches-each having wipers for connecting a calling and a called line, a plurality of stationson the called line, a plurality of ringing current generators for selectively signaling said stations, and relays associated with one of.,said

mama

switches and controllable'by the movement of the wipers of said switch: when operated by the calling subscriber, said relays providedwith means whereby they conjointly control the selection of any one 'of said generators.

18. In a telephone system, means for connecting acalling and a called line including a plurality of trunk lines each terminating.

in 'a connector switch, a plurality of stations on the called line, a plurality of ringing current generators for selectively signaling said stations, means whereby the calling subscriber selects one of saidgenerators in one operation and one of said trunk lines in a separate operation andmeans whereby the selected generator is extended over a conductor of the selected trunk line to theassociated connector switch. v

19. In a telephone system, a plurality of selector switches each having movable ter minals, fixed multiple terminals in eachselector accessible to the. movable terminals thereof, fixed non-multiple terminals in each selector also accessible to the movable terminals thereof, and selective ringing equipof selector switches, trunk lines connecting the two kinds of switches, ringing current generators for selective signaling associated with said selectors, and means in each selector for selecting one of said generators in response to one digit and for extending connection therefrom over one of sa1d trunk lines to one of said connectors, and means 'for'operating the selected connector in response to another digit to connect with and signal a called line. 21. In a telephone system, a connector switch, a' selector-switch for extending connection tosaid connector, ringing current generators selectable by said selector, means for causing successive 'OPGIYMJIOIIS of sand selector to select one of said generators and to combination with a plurality of ringing current generators, of means controllable by a calling subscriber for selecting-one of said generators, a trunk line for extending connection to a called line, having a pair or talking conductors and means for applying a selected generator to the calledline,.separate from the talking conductors via a con-- ductor of said trunk line, said last means comprising an automatic progressively move able switch at each end of said trunk line.

23. In a selective signaling system, four generators arranged in pairs, a relay for selecting either pair, a second relayfor selecting either generator of the selected pair,

means whereby said relays are controlled by a calling subscriber, and means whereby the selected generator is applied to a called line to signal a. subscriber thereon, said last means comprising an automatic progres sively movable switch.

24. In a selective" signaling system, four generators arranged in pairs, a'relay for selecting either pair, a second relay for selecting either generator of the selected pair, means whereby said relays are controlled by a' calling subscriber, and means whereby the selected generator is applied to'a called line to signal a subscriber thereon, said last a means comprising a plurality of automatic progressively movable switches.

25.. In atelephone system, .an automatic switch for use in connecting a' calling and a called, line, a plurality of stations on the called line, a plurality of ringing current generatorfor selectively signaling said stations, relays controlled by said switch, said relays provided with'means whereby they conjointly accomplish the selection of any one of said generators, and a second automatic switch for completing a connection from the selected generator to the "called line.

26. In a telephone system, a plurality I of selector switches each having movable terminals, fixed multiple terminalsin each selector accessible to the movable terminals thereofffixed non-multiple terminals in each selector also accessible to the movable terminals thereof, selective ringin equipment said movable and non-mu tiple xed terminals, and connector switches accessible to said selector switches and selectable through the cooperation of said movable and multi ple fixed-terminals.

. 27. Ina selective signaling system, a plurality of sources of current of difierent char- I acter, a plurality of lines, a pluralityof sig- 1 nals on each'line corresponding to said "different sources, a plurality of trunk lines each terminating in a progressively movable automaticswitch, said switches having access to said lines, another progressively movable automatic switch having access to said trunk lines, means for selecting one of said current sources, means for operating said last switch for selecting one of said trunk lines and its associated automatic switch and for estab- .lishing a connection over theselected trunk 1 line from the selected current source to the automatic switch, said switch having access to said lines, another progressively movable automatic switch having access to'said trunk lines, means including relaysindividual to said last switch for selecting one of said current sources, means for operating said last selected switch, and means for then operatswitch for selecting one of said trunk lines and its associated automatic switch and for establishing a connection over the selected trunk line from the selectedcurrent source to the selected switch, and means for then operating the selected sitch to connect the selected current source to one of'said lines to operate a desired signal thereon.

29. In a selectivesignaling system, a pair of line conductors, a plurality of current sources, a plurality of signaling devices corresponding to said sources connected to both conductors, an auxiliary conductor, a switch for connecting said auxiliary conductor with any one of said sources, and means for placing the connected auxiliary conductor into connection with one of said lineconductors, whereby anyone of said signals may be operated;

30. In a selective signaling system, a pair of line' conductors, a plurality of current sources, a plurality of signaling devices corresponding to said sources connected to both erated, and means for automatically conconductors, an auxiliary conductor, a switch trolling the operation of said switch over said for connecting said auxiliary conductor with line conductors for the purpose set forth. 10 any one of said sources, means for placing Signed by me at Chicago, Cook county,

5 the connected auxiliary conductor into con- Illinois, this 12th day of August, 1916.

nection with one of said line conductors,

whereby any one of said signals may be op- WINFRED T; POWELL.

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