US1640157A - Party-line automatic telephone system - Google Patents

Description

Aug. 23, 1927.

R. G. RICHARDSON ET AL PARTY LINE AUTOMATIC TELEPHONE SYSTEM AImran nr 13. @mandarin-Jahn I Beugmg Burzi-Lag 1,640,157 Aug' 23 1927' R. G. RICHARDSON ET Ax.

PARTY LINE AUTOMTIC TELEPHONE SYSTEM Orizinal Filed Feb. 1. 1925 SheiSx-Sheet 2 Aug. 23, 1927.

R. G. RICHARDSON ET AL PARTY LINE AUTOMATIC TELEPHONE SYSTEM Original Filed Feb. l. 1923 3 Sheets-Sheet 3 MDI /ffff w1 Encfneg E mharnVS/:m-Jnhn lEEUaz-mjf 7?/ @M9 .En-g f;

Patented Aug. 23, 1927.

UNITED STATES 1,640,151 PATENT OFFICE.,

RODNEY G. RICHARDSON, OF CHICAGO, AND JOHN I. BELLAMY, OF BROOKFIELD, ILLINOIS, ASSIGNORS, BY MESNE ASSIGNMENTS, TO AUTOMATIC ELECTRIC INC., Ol' CHICAGO, ILLINOIS, A CORPORATION F DELAWARE. I

PARTY-LINE AUTOMATIC TELEPHONE SYSTEM.

Application led February 1, 1923, Serial No. 616,429. Renewed January 5, 1927.

The present invention relates to party line'automatic telephone systems in general, but is concerned more particularly with systems of the above kind in which the ycharacter or the nature of application of the ringing current or'signalling a called party line subscriber is determined by a terminal individual to each station, reference vbeing had to the co-pending application of Owen l0 et al., Serial No. 246,643, filed July 25, 1918; and the main object, briefly stated, is the production of new and improved circuit arrangements whereby the amount of equipment used in a system of the above character to select the ringing current to be applied to a called party line is reduced to a minimum; whereby the operationV of the system from the standpoint of the wire chief and his assistants is simplified; and whereby the marginal fea-tures found in prior systems of the same nature are removed.

Another object incidental to lthe carrying out of the main object is the provision of circuit arrangements whereby a. simple single-motion switch individual to each connector in the system picks out the ringing current in accordance with the connection of the individual ringing current vselecting terminal of the called station.

Other objects which are concerned mainly with the circuit details will be met with and fully explained during the course of the specification. j

The drawings, comprising Figs. 1 3, inclusive, which accompany this specification show by means of the usual circuit diagrams a sufficient amount of apparatus in a system of the type to which the invention relates to enable the invention to be understood and its 4u utility appreciated. v

Fig. 1 ofthe drawings shows the substation A of which the line terminates at the exchange in the line switch C; the first .selector E accessible to the line switch C;

and also the second selector F (denoted by the dotted rectangle bearing that reference character) accessible to the iirst selector E.

Fig. 2 shows the-connector H accessible to the second selector F, Fig. 1, and having ac- :30 cess to a number of lines. One of these lines is the party line on which the` substation A is located. This drawing shows also the frequency selecting switch FS which is individual to the connector H, and the common controlling switch OS which is common to all the connectors in the exchange. Also, the intermediate distributing frame I. D. F.

and the main distributing frame M. D. FA` Y quency selecting switch F S andthe slightly different control switchv OS which is necessarily diierent on account ofthe different scheme utilized in setting the frequency selecting switch. v

Referring now particularly invention'will be described generally with reference thereto. The line of substation A terminates as usual at the line side of the main distributing frame M. D. F., and is connected by the two-wire jumper 193 to the protector or switchboard side ofthe M. D. F. The protector side of the M. D. F. is connected by switchboard cables to the line switch side of the intermediate distributing frame I. D. F. The three conductors for the line switch are taken oi the line switch side of the I. D. F., as shown. Since the line of substation A is a party line, the associated contacts on the line switch side of the I. D. F. are not jumpered directly to the connector bank side of the I. D. F.,but are connected by means of the jum er 192 to a so-called idler-block, one of t ese being used for each four-party line.

The idler block `shown has five sets of terminals. One of these sets of terminals is used up by the jumper 192.', leaving the other four sets of terminals for use in running jumpers, such as 191, between the idler block and the connector bank side of the I. D. F. The idler block shown, it may be stated, is representative of the others.

The contacts of the connector banks are cabled over to the connector bank side of the I. D. F. and are there connected up in order. Each set of connectorbank contacts represents av station which may be al station on an individual line or a station on a party line, depending upon to where the associated jumper, such as the jumper 191', is connected. Any four sets of terminals, in the same group or in different groups of connectors, may be assigned to anyparty line. For instance, in the drawing the fifty cycle station on the party line shownhas been asto Fig. 2, the

signed the set of terminals 157-160, and the other stations, sixty cycle, thirty three cycle, etc., may have assigned to them any of the ninety nine other sets accessible to the same connector or sets accessible to other groups of connectors, merely by running the proper jumpers.

I/Vhen a party line station is signalled, it is necessary that the Signalling be done in such a manner that the other stations on the line are not signalled. In this particular case, it has been chosen to use the so-called harmonic system of ringing. The four generators which supply the harmonic ringing current are shown diagrammaticaliy in the lower left-hand corner of the drawing, and they furnish ringing current of the proper frequencies to selectively operate the tuned ringer-s on the part-y lines.

In order to choose between the four sources of ringing current when any particular station is called, the frequency selector FS is provided for the connector H and is operated over the common impulse conductor 177 after the associated connector has been set on the called line. rIhe frequency selecting switch FS is guided to pick out the particular frequency desired under the. control of relay 105 of the connector H, which relay, in turn, is controlled in accordance with the cross connection of the bank contacts engaged by the ringing current wiper 155 the connector I-I.

The contacts in the bank of wiper 155, of which one is provided for each station called by way of the connector H. are cabled to the left-hand side of the I. I). F. along` with the line and test contacts as shown. 4Since there are four connectoi1 bank contacts in each set, the jumpers, such as 191, are four-conductor jumpers and the fourth conductor of each connects with one of the four stop conductors 191-194, inclusive, which are connected to the idler blocks, as shown. The correct stop conductor is, therefore, connected back to the ringing current terminal of each station, and provides for controlling the frequency selecting relays, such as relay 105 of the connector H in such a manner that the frequency selectors, such as the frequency selector FS, are set for any one of the four frequencies of ringing current, depending in any one case upon which of the four sets of terminals on thc idler block the terminals of the selected station are connected to.

rllhe line switches of the system, of which only the line switch C, Fig. 1, is shown, are mechanically of the well-known rotary type of which the wipers have no normal position and move in a' forward direction only. The selectors and connectors, such as E, F.y and H, Figs. 1 and 2, and I-I of Fig. 3, are of the usual vertical and rotary type and. accordingly, their bank contacts are arranged in horizontal rows or levels.

The frequency selecting switches, such as the frequency selecting switch FS, Fig. 2, and the frequency selecting switch FS, Fig. 3, are of a simple type of single-motion switch, being operated in a forward direction by their respective operating magnets and rcstored to normal by their respective release magnets.

The control switches CS, Fig. 2, and CS. Fig. 3, have wipers which are moved in a forward direction only by their respective stepping magnets. These switches are of the type of which the wipers a're advanced upon the deenergization of the associated stepping magnet rather than on the energization of said magnet.

Throughout the drawings, the relays which have slow acting characteristics are denoted by the shading on the lower ends of their cores or else by the solid black portion on the upper ends of their cores. The relays which have cores shaded on the lower end are the usual so-called slow acting relays and are slow to fall back but not noticeably slow to pull up. On the other hand, the re.- lays which have the upper ends of their cores shown solid black are slightly slow to pull up, in addition to being slow to fall back.

In order to explain the operation of the system, it will be assumed that. the subscriber at substation A desires to converse with the subscriber at` the party line substation A, Fig. 2.

When the receiver is removed at substation A, line relay 14 energizes over line conductors 11 and 12. Uponenergizing relay 14 places ground on private noi f conductor 9 at armature 20, thereby making the calling line busy, and closing' a circuit for switching relay 13 and stepping magnet 15 in series. As a further result of the energization of line relay 14, it connects test wiper 22 to the junction of switching relay 13 and stepping magnet 15 at armature In case the trunk upon which the wipers of the switch are standing` is i die` switching relay 13 energizes immediately. Assuming the trunk to be busy, however,switching` relay 13 is short-circuited by the ground potential encountered by test wiper 22 on the busy test contact and does not energize, and the wipers are rotated step by step by the buzzer-like action of stepping vmagnet 15, which is operated through test wiper 22. When an idle trunk is reach-ed. which trunk itwill be assumed is the one terminating in nei-10,11#

cuitr atarrnaturel'?, and at armatures16 andI 18 disconnects line conductors 11k and 12 from the winding of line.- relay 14 and ground, and extends lthem by way of wipers 21l and 23, bank'contacts 24 and 26, conductors 27` and 29.armatures 57 and 60 and their resting contacts, to the upper and lower windings of; line relay 35 of' the selectorE.. n

Line relay now energizes Vover the call-v ing subscribers loop afndcloses at armature 51 a circuit for rele-ase relay `36. Upon energizing, release relay 36Vopens a point in the circuit of release magnet iand prepares a circuit for vertical magnet at armature 53, and at armature 52 places ground on releasetrunk'conductor 28, thereby closing the usual hold-ing circuit for switching relay 13'of'the linev switch C before quick-acting line relay 14 has had time to deenergize.

When the calling subscriber operates his calling device in accordance with the first digit in the desired number, the circuit of l.line relay 35 is opened a corresponding number of times. Each time line relay 35 deenergizes in response to one ofthe interj ground by Way of the rest-ing contact of armature 59 and said armature, armature 51 and its yresting Contact, armature 53 and its working contact, relay 37, and vertical magnet 40 to battery. By the operation kot vertical magnet 40, the wipers 61-63, inclusive, are raised opposite the desired'level of bank contacts. Relay 37 is energized' in series with vertical magnet 40 and, being slowacting, .retains its armature attracted throughout the vertical movement. As a result of the energization of relay 37 a circuit is closed at armature 54 for stepping relay 38by way of ott normal contacts 43 (which close upon the first vertical step) and inte-rrupter contacts 42. Stepping relay 38, upon energizing, closes a locking-circuit for itself at armature 55. and at arma.- ture 56 prepares a vcircuit for rot-ary mag.- net 41. f

At the end of the Vertical movement, slowactingfrelay 37 deenergizes and completes the circuit o't rotary `magnet 41 at armature 54, Rotary magnet 111,L upoir energizing, advances the Wipers 61-63,'inclusive, into engagement witlrthe first set of bank contacts in the selected. level, and, near the end of its stroke, opens the circuit of stepping relay 38 at interrupter contacts 42. Stepping relay 38` upon deenergizing, opens the circuit ot rotary magnet 41 at armature 56.' Whereupon rotaryy magnetV 41deenergizes also and closes its interrupter contacts 42 again. In cafe the trunk'terminating in the first set of bank contacts is idle, switching relay 39 energizes immediately. Assuming the trunk to be. busy, however', switching relay 39 isi short-circuited by the ground potentialen'-` countered by test wiper 62, and steppingre.--` lay 38 energizes from tliis same ground po-'l tential and closes the circuitvof rotary magnet 41 again, whereupon lthe switch wipers are rotated into engagement with the nextv set of bank contacts. This alternate ope ation of stepping relay 38 and rotary magnet 41 continues until an idle. trunk is reached, which trunk it will be. assumed is-the one terminating in bank contacts64-66,` inclusive whereupon switching relayf 39, being no` longer short-circuited: energizes in seriesuith stepping relay k38; Stepping relay 38,

however. does not energize. at thistin're on ac count ot the high'resistance of switching relay Switching relay 39, upon energizing, opens a point in the test circuit andl prepares the holding circuit at armature 58 disconnects ground from armature 51 otV line relay 35 at armature 79. thereby opening the circuit of release relay 36'; and at armatures 57 and 60 disconnects conductorsl 275 and 29 from the windings ot' line relay 35. and ex'- tends them by way of wipers 61 and'63 and' bank contacts 64 and'66 to the windings ot the line relay' not shown) of the selector-F.

When the subscriber operates his callinefI device inaccordance with the second digitl in the desired number. thev selector F raises itsl wipers opposite the desired levelof'bank contacts and. upon the f initiation of` the. trunk selecting movement. selects an idlel trunk, which trunk, it willbe assumerh is the one comprising conductors- 67-69,` inclusive. and extending to the connect-or Hv Fig. 2. ln response to the ,seizure ot this trunk line relay 101 ot thc connector H enfergizes over the calling line and clossa' circuit tot' release relay 103'atarmature 131i Release relay 103. upon energizing, prepares a circuit for' vertical magnet 11.1 at armature, 134: prepares a circuit for rela-ys 107 and 109 at armature 133; and at armature.y 1.32' places ground on release `trunk conductor 68. thereby establishinel the usual holding eircuit for the, switching relays ot' the lire .switch C and the selectors E and-'F Then the calling subscriber operates hiscaljling device in accordance,- with the'next digit in thel dcsired'munber. the circuit of line relay 101 ot'the connector H opened a coriesponding numb-er of times and. inon- ,aeh ot' theresulting deenergizations ot line relay 101 a circuit isv closed. for verticalY magnet 111. the, circuit at the time oiE the; first closure being as follows: from ground by way of armature 131v and-its retinaY contact'. armature 134 and its working contact. Contact oi oilr normal spring 114 and said spring. relav 104. and verticalrmafrnet 1.115%0 battery, By tlie'operation of, vertical magnet 111` ytho,wipers 153-156, inclusiv-e. of' the connector Ht aro-raised step by step normal springs have shitte until they stand opposite the desired level of bank contacts. which in this case is the level in which the line of substation A terminates. Relay 104 is eu-erolzed in series with JJ vertical magnet 111 and` slow-acting,

"tions of line relay 101. the first impulse current being` sent over the following circuit: 'from ground by way ot armature 131 and its resting Contact.y armature 134 and its working' contact, normally open contacts controlled by off normal spring' 114, arma ture 185 and its restino' contact, resting; contact of armature 144 and said armature. resting` contact of armature 151 and said armature, and rotary magnet 112 to battery.

By the operation ot rotary magnet 112` the wipers 158-156, inclusive, are rotated step by step into engagement with the terminals ,157-160, inclusive. ot the desired line. Relay 108 is energized in multiple with rotary magnet- 112 and, being slow-acting'. is maintained energized throughout the rotary movement. Upon energizing?, relay 108 disconnects test wiper 154 trom the upper winding of switching relay 109 and connects it with busy relay 107 at armature 146 and at armature 147 places a shunt around armature 144 and its resting contact oit busy relay 107 so as to guard its own lcircuit and that of rotary magnet 112 from beine` opened A prematurelyV by busy relay 107, in casethat relay energizes during' the rotary movement due to test wiper 154 passing over busy tert contacts.

Assuming the called line to be busy, test Contact 158 is grounded and busy relay 107 is accordingly energized when the switch wipers come to rest on the desired set o contacts, and relay 108, upon deenergizing; at the end of the rotary movement, completes a locking circuit for busy relay 107 as follows: from ground by way of the working contact of armature 133 and said armature, armature 143 and its working; contact, normally closed contacts controlled by armature 146` and busy relay 107 to battery. Also, since busy relay 107 is energized, slow relay S, upon l'alling back, disconnects itself and yrotary magnet 112 from the operating circuit so as to prevent any further operation of the switch wipers and any further operation of relay 107 in case the calling subscriber should again operate hiscalling device. Busy relay 107 at its lower armature connects the busy lead to the lower heavy talking conductor, thereby sending back the usual busy tone to the calling subscriber to. interni him that he cannot obtain the desired connection tor the time'beinp. Upon hearu ing` this tone., the calling subscriber replaces bis receiver, whereupon the partly established connection is released in the usual manner.

issuiningnow that the line ot substation r1 is idle when substation. A. is called as llereinbelfore described, test contact 158 isv not grounded and busy relay 107 is consequently not enernized when the switch wipers come to rest on theterminals of the desired line, and slow-acting relay 108,upon deenergjizing, con'iple'i'es a circuit for the upper winding4 et swvichir-.g` relay 109 in series with the switclnng,- r ot the line switch (not shown)- asso the called line as follows: "ir ot the worlfl said armature, ari u contact, upper windir 109, resting contact said armature,

i with iature and d its resting clungf relayv u l 14o and test contact 158, private noi-nini 'or 102, and

thence to battey n oi the switching relay ot the line switch associated with the called line. '111e switc" ingv relayr et the called line switch, which relay corresponds to switching relay 1S oY switch C,

Fig. 1, energizes L owingl to the us il nei arrangement bctw' en i ot the associated line this switchino relay c battery and ,ground coi line but does not connect up the associated wipers.

1n the coni upon e er relffiy ot tne call loclringcircuit justed armature 150, ground on test w per conn line wr and an tary magne @rating cirr l 105 thi-enga att-er t" 's occnr its lirst or sii-ith contact of stepping magnet 17S, on the common nicloun by closing' circuit iter tolle-ws: from ground by. pick-up con uci'er 170, 175 o1' the trcijiencv closed contacts co of relay 105,.relay 10o. i ing contact offarniature at this time interlocking rinature and tiat ay. Consequently, onnects the normal rector fi. w Ll cisne ne ance 115, work- 151 and arma l round by wayv mature y connects up Wiper 155 atarmaturc 137 disconnects wiper 173 of the )fre- .quercy lector FS at armature A1439;..and at re 138 connects -up stepplng con- Upon. the'next energization of control relay 180, the usual-circuit isclosed for-stepping' magnet 178 of the' control switch .at

:L imture 182,7Whereupon magnet `1781el1ergizes and moves the yassociated'pavvl into engagement with thev next .notch on -the ratchet wheel but Adoes :not advance Wiper 179. As a further result of the -energization ot relay 180, ground Yisplacedon thecomincn stepping conductor '177 .at .armature A181, thereby closing a-circuit torfstepplng magnet 172 of the -trequency selector. Step- .ping` magnet- 172 nowenergizes and advances the Wip-ei' 173 into engl Uementiwitht er lirst assi iared bank contact. 1

. .ontlze subsequent deenergizationzofrelaf.' 180. the circuitof stepping magnet .178 ot'l the control switch CS ris opened vand rzground is removed fromstepping conductor 177. Upon the decnergization of .stepping Vmagnet 178, the Wiper .179 `'is advanced finto,

engagement with the bank Contact .inwhioh the lirst stop conductor 191 terminates#- 'thereby placing' a yground on saldstop conduct-or 191. This, however, Adoes :not :have any ell'ect as regards the connector H. .The

Wiper 178 isadvanced vagain upon each of i the subsequentenergizations of control relay 1801until said W1per173 comes :into engagement with .the third associated Ibank Contact or the one which isfassociated with the titty-cycle generator. This occurs, of course, While control relay 18() is energized and While Wiper 179 of the controlswitch CS .ison the bank contact-1in Whichthe :second stop conductor 192 terminates.

:Upon the nen` deenergization zol'control relay 180, stepping magnet- 178 Adeenergizies and advances Wiper 1179 into 'engagement with thc lbank contact in vWhich the third stop conductor 193 terminates. Since Vthe t jumper 191 is connectcdwvith 4the ffourth set or the fifty-cycle set oftermin-als onitlie idlerblock, lground is placed on ringing current terminal 159 ot the called stat-ion Aby Way of the control switchCS, the fifty-cycle stop conductor 193, a conductor ofjumper 191', and ccndnctor 163 to bank contar; 150. This ground potential is Vextended through wiper 155 vand .armature 137 fand its Worllzing contact `toit-he junctionfof frelay 105 and resistance 115,' thereby short-'cil'-` cuiting relay 105. .Relay 105 accordingly.

`deenergizes; disconnects the common stepvping .conductor `17:7 from .stepping magnet .172-01 the frequency selector .at armature :138; andzat Varmature 139 connects up .Wiper 1.73, Vwhereupon ring-ing .current from the selected source is intermittently projected outon .thecalledlind returning vby Way of ythe-.upper talkingconductor and the upper Winding of ring-cut-off .relay .106. Relay 105.is not operated again whenipick'up conductor 176 is nextgroun'ded, `for .the 4reason y ythat ofi' normal contacts 175l of the fre- .qurency .selector FS are. now lopen. .As .is .well-known, the .ringing vcurrent .projected .out on .the called vline passes Vthrough the .four xbridged bells in multiple. `However, onlyV thcgbellfat substation ,A .responds because itis .the only one tuned to 'the frequency of ringing current that is beingsent out.

vVVhenthe subscriberat substation :Afrespon-ds to the lringing ,of` his bellby removing his receiver, adirect'current bridge is closedk across the conductors of A.the called line, whereupon ring-cut-oil" relay 106 lenen .gizes through its upper Windinggvcloses a.

lockingr circuit vfor itselt` at its (lightly `adjusted armature .141; and at armatures 1140 `and .1412' disconnectsthe line lWipers from its own -upper .winding and-the source effingingcurrent and extends them tothe windings of batteryyfeed impedance 102.y The calling. and l called subscribeis .mayniow converse Vwith each other as desiredwo'ver the .talking -circuit -Which .is outlined yby `the heavy conductorsand, 'when .the conversation .is terminated, they replace their .rece1vers. v

VVhenthe receiver is replacedat thecalled substation A', the vdirect current bridge is removed from .across the .line conductors, .and talking battery-ceasesto 110W.

llVhen thefreceiver'is replaced'at `the callingfsubstation A, the .circnitfof .line relay i101 of the connector YH is lopened .and vline relay .101 accordingly f deenergizes and `opens the'pcircuit of release'relay 7103. Slow-actingreleaselrelay .103 now deenergizes in response tothe prolonged opening'ofitscrcuit.; removes :ground yfrom release trunk conductor 68 at armature l132, 'whereupon relays 106and :109 deenergize;zand iitarmature 134 closes-'a circuit "for release magnet 110 by Way of olfV rnormal vcontacts.,1`13. vUpon the energization of release magnet 110, the Wipers '153-156, inclusive, of; the .oonynector H are .rest-cred to 'normal position in vthe lusual manner, and' the circuit of release `magnet 110 is opened at ov'normal contacts .113 when vthe Wipers reach their normal position.

As i a further Iresult of Sthe -vdeenergization .of release frelay v103, fa circuit fis closed :for release magnet 1710i .the frequency :selector FS in multiple with release magnet 110 and through off normal contacts 174. `Wiper 173 is restored to normal position upon the energization of release magnet 171, and the circuit of release magnet 171 is again opened at olf normal contacts 174 when wiper 173 reaches its normal position.

As a further result of the ground potential being removed from release trunk conductor 68, the switching relays of the line switch C and the first and second selectors E and F decnergize. rl`he deenergization of switching relay 13 of the line switch C restores conditions in that switch to normal. The deenergization of switching relay 39 of the selectorE closes a circuit for release magnet 44 at armature 59 by way of armatures 51 and 53 and off normal contacts 45. Upon the energization of release magnet 44, the wipers of the selector E are restored to normal position in the usual manner, and the circuit of release magnet 44 is opened at olf normal contacts 45 when the wipers reach their normal Y position.

The selectorF is restored to normal in the same way as the selector E.

Referring now particularly to Fig. 3, the operation of the modification will be described.A It will be understood, of course, that the int-errupter 230 is constantly operating with the result that the control switch CS is being constantly driven around in a manner similar to the control switch CS as above described. It may be pointed out, also that whereas the control switch CS, Fig. 2, has, for each cycle of operations, a definite position (the position at which the common pick-up conductor 170 is grounded) at which it starts the waiting frequency selectors, and has a plurality of positions at which it stops the operating frequency selectors (the positions at which the four stop conductors 191-194, inclusive, are grounded), the control switch CS has, for each cycle of operations, a definite stop position at which it stops the frequency selectors which are being operated, the frequency selectors such as FS being picked up or started at the correct position by the four pickup or start conductors 231-234, inclusive.

Assuming now that the substation A2 is being called; that the wipers of the connector IVF-have been set on the terminals of the line` of substation A2; and that the called line is idle, switching relay 203 energizes in the usual manner and prepares a circuit for pick-up relay 202 in series with rotary magnet 209 at armature 208. After this occurs, a circuit is closed for pick-up relay 202 when wiper 226 arrives upon the bank contact at which pick-up conductor 233 terminates. This circuit is as follows: from ground by way of wiper 226, pick-up conductor 233, a conductor of jumper`252, bank contact 251, wiper 250, normally closed contacts Acontrolled byl armature 206, pickup relay 202, olf normal contacts of the frequency selector FS', working contact of armature 208 and said armature, and rotary magnet 209 to battery. Pick-up relay 202 energizes over this circuit, but neither rotary magnet 209 nor the relay which is in multiple with it energizes at this time on account of the high resistance of relay 202. Upon energizing, pick-up relay 202 closes la locking circuit for itself and opens its initial circuit at armature 206, and at armature 207 connects up impulse conductor 223 to rotary magnet 221 of the frequency selector FS by way of the slow-acting series relay 201.

vrThe above mentioned energization of pick-up relay 202, it will be observed, occurs in response to the advance of the wipers 225 and 226 of thecontrol switch CS and, consequently, occurs during the time that relay 227 is deenergized, the wipers of the control switch CS as pointed out above, being advanced upon the deenergization rather than the energization of the associated stepping magnet 224. Accordingly, since relay 227 is deenergized at this time, impulse conductor 223 is not grounded and stepping magnet 221 of the frequency selector FS is not energized immediately.

Upon the next energization of control relay 227, magnet 224 is energized, upon armature 228 being attracted, and prepares to step the wipers upon its subsequent deenergization. As a further result of the energization of relay 227, the common impulse conductor 223 is grounded at armature 229 by way of wiper 225 and the bank contact upon which it is standing.

This closes a circuit for stepping magnet 221 by way of armature 207 and its working contact and relay 201. VRelay 201, upon energizing in series with magnet 221, places a shunt around olf normal contacts 253 at armature 204 so as to maintain the circuit of pick-up relay 202 intact after off normal contacts 253 have been opened. As a further result of the energization of relay 201, wiper 222 of the frequency selector FS is disconnected at armature 205 so as to prevent any ringing current from being proiected out on the called line while wiper 222 is being operated. Stepping magnet 221, upon energizing, advances the wiper 222 into engagement with the first associated bank contact. Upon the subsequent deenergization of relay 227, ground is removed from the common impulse conductor 223 at armature 229, and the circuit of stepping magnet 224 is opened at armature 228. Upon deenergizing, stepping magnet 224 advances the wipers 225 and 226 into engagement with the next set of bank contacts.

vUpon the next energization of relay 227,

Vwhich is the third ground is again applied tothe impulse conductor 223, thereby closing tliefcircuit of stepping magnet 2,21 and series relay 201 the Ivaiices Wiper 222 into engagement With the third associated bank lcontact, which is the banl contact with which the desired frequency of -ringing current-is connected.

Upon the subsequent deenergization of relay 227, the co1" ion impulse conductor 223 is ungrounded Lgain, and the Wipers 225 and 226 are Yadvanced into engagement With one of the Ydead sets of banlr contacts. Accordingly, impulse condnctoi223 is not grounded upon the next energization of relay 227. This produces an extra longl interval between the impulses oi current delivered over impulse conductor and allows time for the slow-acting relay 201 in series with magnetv 22l to energize. relay 201 removes the shunt i'rom around off normal contacts 253 at' armature 204, thereby opening the circuit ol pick-up relay 202. Upon deenergizing, pick-up relay 202 disconnectsl the impulse conductor 223 from the stepping magnet of the frequency selector at armature 207. As a i'urther result of the deenergizatioii oiv slow-actingT relay 201, it connects up wiper aty arii'iature 205, Whereupon ringing current from .thev selected source is projected out overv the called line to ring the desired bell. The remaining part ofthe operation is as described in connection 'Sith Fig. 2.

'lt is very evident that the frequency selector FS may be set tor any of the four frequencies when the Wipers of the connector H are set on the terminals shown, by merelyronnecting the jumper 252 to any one of the four sets of terminals of the idler block, the pick-up relay 202 being operated sooner or later during the cycle of operations of the control switch CS', depending upon which ot the tour pick-up conductors 231- 23st, inclusive, is' used.

Regarding the signalling ot substations on individual lines, it may be said that the ringers at these substations do not ordinarily'ha-vo harmonic bells and` are signalled with the thirty-three cycle generator, that being the one to Whici these bells respond mostreadily. For example, the substation not dcenergiz d between Y Upon deenei'gizing, f

A, ZFig. 1vvhich is reached as acalled slibstation by Way of the normal conductorsl 7-10, inclusive, is signalled by thev thirty.- ithree'cycle generator as is indicated by the single Wire jumper 6 which is run to the thirtysthree cycle stop conductor bus-bar.

'It will be noted in this connection that it is not necessary to use four conductor jumpers i'or` the individual lines, the ringmgcurrent selection beingtake'n care of for theserlines by a short single wire kjumper run tofu nearby bus-bar.

Although certain forms of the invention have been described in' detail, it is .understood that We do not Wish to be limited Vto being called by Way-of its associated set of teiminals,.connector switches for extending connections to the desired lines by way/of said terminals, a step by step ringing current selecting switch associated With each connector, and means controlled in aocordf ance with the set ot' terminals on which a connector is set for operating said selecting `switch to select the correct ringing current to signal the called station.

2. In a telephone system, party lines, a connector switch having Wipers for extending connections to said lines, a ringinor current selecting switch individual to sai connector switch, and means controlled according to the setting of said Wipers for subsequently operating said selecting switch.

3. In an automatic party line telephone system, a. connector switch for completing connections to called party'lines, a plurality of branches for each line over which connection thereto may be completed, and an auxiliary progressively movable ringing current selecting switch associated with said connector and controllable over the particular branch in use when any line is connected with.

Y 4. In a party line telephone system, alink circuit for completing connections to-called party lines, a plurality of branches for each line over which connection thereto may be completed, and a progressively movable ringing current selectingswitch associated With said link circuit and controllable over the particular branch in use when any line is connected With.

pleted, each branch `correspending to a particular station on said line, ringing current generators equal in number to the number oi said -tations, and a progressively movable switch controlled over the branch in use when said line is connectec with to select the proper generator' for vsignalling the desired station.

6. In a party line telephone system, a link circuit for completing connections to a called party line, plurality oi branches over which connections to said line may be conipleted, each branch corresponding to a particular station on said line, ringing current generators equal in number to the number ol" said stations, each generator being adapted to operate the bell at a particular station only, and a progressively movable switch controlled over the branch in use when the line is connected with for selecting the 4generator corresponding to such branch and to the station which it is desired to signal.

7 Ina party line telephone system,'a link circuit 'for completing connections to a called party line, a plurality ot branches over which connections to said line may be completed, each branch corresponding to a diherent station on said line, ditlerent ringing current generators equal in number to the ininiber of said stations, a switch and means tor operating it to select one ot said generators, and means controlled over the particular branch in use when the said line is connected with for determining which generator is ,fvelected by said switch.

'8. In a party line telephone system, a link circuit for completing' connections to a caller party line, a plurality ot branches over which connections to said line may be coinpleted, each branch corresponding to a dil*- ferent station on said line, dii'lerent rino' current generators equal in number to number of said stations, a switch tor selecting the proper generator' t'o signal the desired station when said line is connected with, step by step mechanism for operating said switch to select said generators in order, and nieanf-f controlled over the branch in use lfm' determining the number of steps taken by said switch.

9.l In a selective ringing system, a ringing current selecting switch, a plurality ot control conductors, means tor associating' said switch with any conductor, means tor grounding said conductors successively, 'means tor `generating an operating impulse to move said switch each time a conductor is grounded, and means controlled over the particular conductor with which the said switch is associated tor dctern'iiningej the number of impulses which become effective.

10. In a selective ringing system, a ringing current selecting switch, plurality ot control conductors, means for associating said switch with any conductor, means for grounding said conductors successively, means 'for stepping said switch ahead each time a conductor is grounded, and means controlled over the particular conductor with which said switch is associated when the same is grounded for prevent-ing further stepping et said switch. C ll. In a selective ringing system, a ringing current selecting switch, a plurality of control conductors, means for associating said switch with any conductor, a device for advancing said selecting switch and for successively grounding' said control conductors, and means responsive when the conductor with said switch is associated is grounded tor @topping further advance of said switch.

In a selective ringing system, connector switches Ytor connecting with called lines,

a ringing current selecting' switch individual to ez'. ch connector, a common control switch for operating all said selecting switches, control circuitsI tor determining the extent ot movement ot said selecting switches, and means in each connector for selecting a control circuit whenever a. called line is connected with.

lill. In a selective ringing system, connectorswitches tor connecting with called lines, a ringing current selecting switch individual o each connector', a continuously operating f" ting device Afor operating said selectswitches, a plurality oit control circuits 'roi' determining the extent to which said selecting switches are operated by said device,

and means in each connector for selecting a control circuit whenever a called line is connected with.

l In a telephone system, a party line, a coiinmtor having access to said line over a plurality ot brancher-1, a frequency selector individual to said connector, andin'eans individual to cach branch ttor controlling said 'frequency selector.

1.7:. in a tdephone system, a party line. a connector having access to said line over a plurality ot branches, a frequency selector indi'v'idual to raid connector, a relay in said connector tor controlling said selector, and a conductor individual to each branch for contr-r'illing said relay.

i6. In a telephone system, a party line, a having access to said line over a pluralityV oi" branches, a frequency selector individual to said connector, means for startthe fiaperation of said selector automatiy when the connector connects with any nch, and means controlled over a conduc- :or ot the branch in use for stopping said selecter at a particular point.

l In a telephone system, party lines, a connector switch having wipers for directly connecting with said lines, a ringing current selecting switch individual to said connector luc switch, and means controlled according to the setting of said wipers for operating said selecting switch.

1S. In a telephone system, party lines, a set of terminals at the exchange associated with each station on each line, each station being called by way of its associated set of terminals, connector switches for extending connections to desired lines by way of said terminals, a circuit closing device, a plurality of sources of ringing current, and means in each connector controlled by said device in accordance with the set of terminals on which the connector is set for connecting the correct source of ringing current to the called line to signal a desired station thereon. f s

19. In a party line telephone system, a link circuit for completing connections to a called party line, a plurality of branches over which connections to said line may be completed, each branch corresponding to a particular station on said line, ringing current generators equal in number to the number of said stations, a circuit closing device, and means in said link circuit controlled by said device over the branch in use when the line is connected with to connect the proper generator' to the line for signalling the desired station.

20. In a party line telephone system, a link circuit for completing connections to a called party line, a plurality7 of branches over which connections to said line may be completed, each branch corresponding to a particular station on said line, ringing current generators equal in number to the number of said stations, each generator being adapted to operate the bell of a particular station only, a circuit closing device, and means in said link circuit controlled by said device over the branch in use after the line is connected with for connecting to the line the generator corresponding to the station which it is desired to signal.

21. In a party line telephone system, a link circuit for completing connections to a called party line, a plurality of branches over which connections to said line may be completed, each branch corresponding to a particular station on said line, different current generators equal in number to the number of said stations, a constantly rotating mechanism, and means operable after said line is connected with and controlled by said mechanism over the branch in usel for determining which generator Vis used to signal a desired station on said line. Y

22. lIn a telephone system, party lines, a connector switch having wipers for directly connecting wit-h said'lmes, a progressively movable ringing current selecting switch,

and means controlled according to the set.- ting of said Wipers for operating said selecting switch.

23. In a telephone system, a connector switch, a party line, branches of said party line accessible to said connector, each branch including a control conductor, means for operating said connector to connect with said linev via` one of its branches, a plurality ofA its branches, a plurality of sources of ringing current, means for connecting a source of potential to the branches of each ol said party lines successively, and means in the operated connector operative when said source of potential is connected to the control conductor associated with the branch in use for connecting the proper source of ringing current to the connected line to signal a particular stat-ion thereon.

25. In a telephone system, connector switches, party lines, branches of each party line accessible to Said connectors, leach branch comprising talking conductors, a test conductor, and a selective ringing conductor, means for operating one of said connectors to connect with one of said lines via one of itsbranches, and means common to said lines and controlled over` the selective ringing conductor of the branch in use for signalling the particular station on the line which corresponds to the branch in use.

26. In a telephone system, a connector, a party line, branches of said party line accessible to said connector, each branchcomprising talking conductors, a test conductor, and a selective ringing conductor, means for operating said connector to connect with the line via any branch, and means individual to said connector and controlled over the selective ringing conductor of the branch in use for signalling the particular station on the line Which corresponds to the branch in use.

Signed at Chicago, Illinois, this 29th day of January, 1923.

RODNEY G. RICHARDSON.

Signed at Chicago, Illinois, this 29th day of January, 1923.

J CHN I. BELLAMY.

llO

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