US1533079A - Automatic telephone system - Google Patents

Description

April 7,1925- H 1,533,079.

R. G. RICHARDSON l AUTOMATIC .TELEPHONE SYSTM originan Find ms, 1920 s sneetsfshnt 1 Badi-zeg HEIDI-fardeau.'

April 7, l925- A 1,533,079 R. G. RICHARDSON AUTOMATIC TELEPHONE SYSTEM 'I original Filed nb. fr, 1920 InUEL-z m" Hndney E. Hzchardsan IlHII April 7, 1925. 1,533,079

R. G. RICHARDSON AUTOMATIC TELEPHONE SYSTEM Original Filed Feb. e, 1920 3 Sheets-Sheet 5 a//er .B/ock Patented Apr. 7, 1925.l

UNITED STATES PATENT OFFICE.KA

RODNEY G. RICHARDsON, or CHICAGO, rritrivors, vAssrenon ro Aaron/Lario ELECTnIC COMPANY, or CHICAGO, ranno-1s, a Coaronafrron or iLLINOIs.

AUTOMATIC :TELEPHONE SYSTElWI.

Application 1e i February 6, 1920,Seria1 No. 356,803. Renewed July 16, l192.4.

To all whom t may cof/wem Be it known that I, RODNEY'G. RICHARD- SON, a citizen of the United States of America, and a resident of Chicago, Cook County, Illinois, have invented certain new and kuseful Improvements in Automatic Telephone Systems, of which the following is a specification.A

My invention relates in general to automatic telephone systems, but is Concerned more particularly with automatic party line telephone systems in which means is provided at the exchange for selectively signalling the different stations on the party lines; and the object of the invention may be stated to be the provision of a new and more eflicientV and flexible systenrof this kind than has hitherto been available.'

In my prior United States Patent No.v

1,528,343, issued March, 1925, I have described a system of party line selective signalling in which each party line is accessible by way of as many called line branches as there are stations on the line, thelineand its several'branches being connected at an `hiternfiediate distributing frame, and V in y which frequency selecting connectors are used whose frequency selecting operations are controllable over any called line branch connected with the frequency selection be- `Ying determined by the manner in which the branches are connected to the line at said distributing frame. In a system of this kind the different Call numbers or telephone numbersl have no liXed relation to each other, or to any party line, or to' any vparticular kind of ringing current; and such a system therefore provides for handling Changing and uctuating party line business with a maximum of convenience both to the company and to the subscribers, while securing a maximum eliiciency in the utilization of the central ofce switches outside cable plant. y l

The system above described, however, provides for full metallic circuit ringing on the harmonic principle and on that account the circuits are necessarily 'somewhat corn-V plicated. I have` found that by connecting' the ringers at two of the stations on afour party line fromvone side of the line to and in the cation above referred to, in which the deg sired results are obtained inv al different manner and by` using different and less complicated circuit arrangements. f

Having stated in more or less general terms the objectof the invention, the appa@` ratus and improved circuits used to Carry out the same willnow be explainedv more in detail, reference being had to the' accomV- panying drawings, colnprising'Figs. l, 2,.

and 3, which are circuit diagrams showing the essential features of a .telephone system embodying the invention.

Referring `to the drawings, the substation A, Fig. yl, is an ordinary automatic substation, which, although shown for convenfv ienrce as'being individual to the line,V may equally7 well be a party line substation.y It

comprises the usual talking equipment and ringer, and also a callingdevice indicated by the reference character S, through the mediumvof Iwhich the subscriber controls the entrai oliice switches.

. he line conductors 1l andl?I extend to' the exchange where they terminate in the rotary line switch C in a manner more clearly shown in Fig. Sgin the case of a called line. rIhe vlinel switch C may be briefly describedv as a rotary line switch whose movable terminals or wipers have no normal position', and which have movement in a forward directiononly; The construc-l tion of a line switch of this type is well, known in the art, and its function, also well understood, is to extend the'associatedline when callingto an idle trunklin'ie.'v For this purpose,ja plurality of these individual line switches may be given access to a group of-` trunk lines *extending to first selector switches. One ofthetrunk lines to which the line switch lC haslaccess is shownin the which .gis a vertical and rotary selector switch of the usual construction. The selector D, together' with a plurality of simivlar selectors, has access toa plurality of Ygroups Aof trunk -l-ines, the trunk .lines of eachgroup terminating in a -group of con- Y nector switches. One of the trunk lines to whichmthesselector D has access is shown eXtend'ingto "the'connector E, Fig. 2. The connector E 'likewise 1s =a. `vertical Vand rotary switch of well known construction,

and, except for the circuits having vto do with the selective ringing, is of the usual type which is in common use. It is understood Vthat second and third selectors Amay Vbe-used if desired according `to the capacity ofthe exchange; land itlmay be stated that the system of trunking employed is the same `as the system ycommonly referred to asgthegpercentage trunking system'. A

F ig. .3, I have shownin detail the manner in which al party line is connected for j rboth.incoming and outgoing `service at the main and 'intermediate distributingframes.

The ylayout shown maybe described briefly as follows:v The. four party line comprising conductors '201 vand 202, which has the four `slibstation A to A4, inclusive, connected in bridge thereof, is .assumed to enter the exchange tby way of cable Vpair B2 which. is terminated on the cable side of the main distributing frame in the usual manner.

Thisjcable pair Vis connected by means of a` Vjumper 'with any desired pair on the switchboard side ofthe main distributing frame,.

and may Vbe terminated on the switchboard side of the main distributing vframe as shown, or on the vertical side of the intermediate distributing frame, it is immaterial u vh'ic-h. The jumper on the main distributing'frame having been run, it will be evident vthat the 'party line Vshown will be connectedwfor outgoing servicey by way of the individual line switch C", which has l access to.,

K IaV plurality of Vfirst selectors similar to? the first 'selecto-r D. The line-is-connee'ted for incoming service VVVat4` the' intermediate distributing frame.

On* thel horizontal side of `this frame .aretfermin atedy the normal cables comings-.from allAv the lconnector groups in the exchange., These cable pairs are preferably A arrangedin consecutive order onthe horizon-tallside of the frame in accordance lwith ftheL-call numbers, and the terminal sets should`. beY .so numbered.l This is yshown kclearly .in the drawing wherein the firstV sets cordance with the ynumber of the group according tov any desired numbering scheme;

while the other foursets of each groupy are preferably marked in accordance with the ringing characteristics of the :four stations on theline. As shown in Fig. 3,'th'e1markingsl indicate 33 and 50 cycle ringers connected from the positive vand negative sides of the line .to ground. These markings are not necessary but are'veryconvenient.YV The manner of connecting 4"the line lfor incoming service will now be apparent. Terminal set 1 on the vertical. side 'of the intermediate frame `is connected by means of the triplex jumper 204: with .the upper terminal setof some vacant group von an idler block as for example, the group shown, which is .group #1. Then the other four terminal sets ofl thisgroup areco-nnected by means of v:jumpers 205, 206, 207 and `208 with the terminal sets on 'the horizontal side of the intermediate frameV which correspond 'to the call `numbers whichV have been asigned to the different stations on the party line'. y It is vto Abe clearly understood that any call numbers whatever may be used. The line is now completely'conne'cted for both incoming and outgoing service. l Y

I will now ldescribe vthe operation-ofthe circuits involved with thespecial object of loisv explaining the method `by which the'. stations on a lineare selectively signaled. For this purpose it. Vwill first be assumed that theV g subscriber at substation vA desires to call the subscriber at substationA., whose ringer, tuned to theSS cycle frequency, is connected from line conductor 201 to ground, and whose telephone number, therefore, when the line is connected as shown in the'draw-; ing, willbe #111.' When'the receiver is removed from the-*hook rat substation A,.a circuit vis 'completed over the lineconductors 11 and 12 for the yline relay 14 of the line switch C. Upon energizing, the line relay completes a cir'cuitextending through the switching relay V13 and the stepping magnet v Y 15 in series atV its armature; 20, and at its armature-19 connects the test wiper 26 to the,` above circuit at a pointV -midway between. the switching' vrelay j and Vthe Y said"A stepping magnet. The operation now -depends upon` whetherthe-test contact with which the test wiper V26 is in engagement is busyoris not busy. If this test Contact is busy it 'will have a ground potential upon it,

(lll l the switching relay 13 will be short circuited, and the stepping magnet 15, which interrupts its own circuity will operate as a buzzer to advance the switch wipers -27, inclusive, step by step in search oi an idle truiil-I line. rl'his operation will continue as long as the test wiper 26 engages grounded oi busy test contacts. However, we may assume that iii the present case when the call' is initiated, the selector' l) is idle and the test contact 31 therefore is not grounded` Under these circumstances, when the line relay 14 is energized, the switching relay 13 is energized immediately afterwards, with the result that the line conductors 11 and 12 are disconnected from the winding ot the line relay 14 and from ground, respectively, and are extended by means ot armatures 16 and 18, wipers 25 and 27, bank contacts and 32, and armatures 63 and '85 and their resting contacts to the upper and lower windings of the line relay .50 oli selector D. p

Immediately uponthe e.;tension ot the line as above described the line relay will be energizedy over the line c- 1cuit and will close the circuit ot the slow acting release relay 51. Upon energizing, relay 51 prepares the circuits of the selector for the vertical operation in the usual manner, and at armature 58 completes a holding circuit extending back to the line switch C over the following path: ground at G2,-working contact of armature 58 and the said armature, conductor 90, test contact 31, test wiper 26, armature 17 and its Working contact7 winding of the switching relay 13, and the winding of the stepping magnet 15 to battery. It is understood that the above circuit is established before the slow` acting line relay 14 has had time to deenergize.

The calling subscriber may now operate his calling device in accordance with the iirst digit of the desired number.` A series ci interruptions in the circuit of the linerelay 50 is thereby produced, causingl corresponding series ot deenergizatioiis of `the said ine relay, which at each deenergization sends a. current impulse through the slow acting relay 52 and the vertical magnet 56 in series to battery. By the operation ot the vertical magnet the selector shaft israised step by step until the wipers 7 O-7 2, inclusive, stand opposite the desired level ot bank contacts. The slow acting relay 52 is energized in series with the vertical magnet, retaining` its armature attracted throughout the vertical movement of the switch, and upon the ture 60, and at armature 61 establishes alocking circuit for itselt. At the end of the vertical operation` of the switchthe slowacting relay 52 is deencrgized andL closes the circuit ot the rotary magnet, which is thereupon energized to advance the Wipers 72, inclusive, into engagement with thefirst set of bank contacts in the level oppositewhich they were raised. The rotary magnet also breaks the circuit of the stepping relay l 53, which a co ugly is deenergized to break the circuit 'of the rotary magnet, whichV it, and the 'stepping` relay 53 will be energized again over a` circuit which extendsY from the grounded test contact by way of the test wiper 71, armature 64 and its? resting contact, the interrupter contact'ot the rotary magnet, the ott'. normal springs` G2, and the winding'of the stepping relay,

53 to battery. The stepping relay will there? tore again close the circuit of the rotary magnet 54, which will` operate to advance the switch wipers into engagement with the4 next set oli' bank contacts. This operation. by which the stepping relay and the rot-ary nagnet are `alternately energized and de energized willl continue as long as the test wiper 71 engages busy orv grounded test contacts. In the present case vit will be assumed that the trunk line shown inthe drawings is the first idle trunk line, and when, therefore, the test wiper 71 arrives at test contact 74 and the rotary magnet is deenergized, the

stepping relay 53 will not again be energized; l i

but instead the switchingv relay.. 55, which hitherto'has been short circuited,rwill be operated by current flowing over `the following path: grounded conductor 90, winding y ofthe switching relay 55, interrupter contact of the rota-ry magnet, oli' normal springs 62, and thewinding oi the steppingrelay 53 to battery. Owing to the high, resistance of the switching relay 55',v the stepping relay 53 is not operated. Upon energizing, relay 55 disconnects the incoming line conductors from the windings of the line relay 50, and extends them by way of armatures 63 and 65 and their working contacts, wipers 70and 72, bank contacts73 .and 75, conductors 76 and 78, and normally closed contacts ofthe back bridge relay 100 to the upper and lower,v windings ot the line relay 101 oit the connector E, Fig. 2. i

the connector E, the line relay 101 isenergized over the line circuit andcompletes a circuit for the slow-acting'release relay 102.'

Upon energizing, relay 102 prepares the cire cuits of the connector for Voperationin its vertical inoveinent, and also closes a holding The calling line havingebeen'eiitended to,

iiov

circuit extending back-to the` selectorl D,

Iwhich may be traced as follows: ground at Y 'contact o'arinature 116 andsaidj afin ure, iconductor77, test Contact V711, test wiper 71, zand armature 64 and its working contact to vconductor 90, where it joins the previously 'described holding circuit entendingba'ck tothe line switch C, and serres to niaintai'nvrelays V55 and 13 energized.

When the calling Subscriber operates his calling device 'in accordance with the Ynext digit in the desired `n-umbeiya series of interruptions is produced in the circuit ci the line Yrelz'i'yglOl, V'whlch accordingly de'energizes a corresponding number of times. At each deeiier'gi'aationjthe line relay transmits a cur-v rent :impulse through the vertical magnet 111 ver the,followingcircuit: ground at G, armature 115 Tand its restingcontact, armature 117 `and yits working contact, off ynormal springsllO 'andV 152, 'winding of the .slow acting relay 103a'nd the 4winding of the.

vertical magnet 111 tobattery. This is the circuit "over 'which the first impulse is trans- V mitted. theV upward step of the switch shaft, however, the oit' normal springs 'are shifted, and theVc-i'rcuit extends `fronrthe vworking contact ef armature 117 by 'way f' oli' normal contact springs 150 and 151, armature 118 and its working contaet (relay 103 being nowen'ergized), winding of relay 103, and the winding of the y vertical magnet 111 to battery. By the operationof theverticalmagnetr v'the switch shaft is raisedstepfby step until the wipers 16C-'162, `inclusive,standY opposite the de- L sired level of bank contacts. At the end 'of the vertical lIn'ovenfient ofjthe switch the slew-acting relay deenergized and prethe switch kfor operation in its rotary movement. u n v e y The 'calling subscriber may now Voperate Vhis 4calling device in accordance with the last digit inthe number, thereby'producing as Y ybefire a series' of interruptionsin the cirfit.

yce'

cuit el: the line relay 101. each resulting deenergizatien ftheline, relay now sends a vcurrent impulse thrughthe rotary magnet 113 'over the following circuit: ground at G4, arjIfn'a-tureV 115 and its resting contact, armature 117 andnits working contact, 'off normal springs 150 vand 151, 4,rniatilre 118 and its resting contact, restingV contact of armature124 and the` saidl armature, resting citaet f armature 135rand the said armature', rand the winding vof the rotary magnet 113 to battery. In response to these irnpulses the rotarygmagnet operates to rotate the wipers 1160462, inclusive, intofengage-` Vment with the desired Vset of bank contacts `in the level lopposite which they were raised,

Since, inthe present case, the desired station is 111, thewipers will have been raised oppositie.y the first level, and they will be rof tated in'to engagement with, thehiirst setl off contras iff 'this level, prjqqacts indicated The slow acting relay 106 is KVener-giZed parallel with the rotary magnet and retains its armatures attracted throughout the 'rotary movement Aof the switch. Atv armature 128v relay 106 connectswthe test .wiper161 to the winding of the ybusy test relay 1.05'and at its armature 129 relay 106 closes a shunt varound 'armature 121 of the Vtest relay and its resting Contact to guard against the possibility of the said'test relay V.being nelmen.-v tarily energized whilexthe testuwiper 161 is passing over busy testrkcontacts.l Il the called line is busy when the testfwip'ery 161 arrives at the test contact associatedr therewith, as, for exan'iple, `the test Contact 172. the test relay 105 will be energized, and

when the slow-acting. relay 106 deenergizes Let it be assumed, however, that the called' line is idle when the connector E is operated as before explained. yto establish connection therewith. Under these circumstances when the switch wipers 160-1'62, inclusive, are

brought to restv in engagement with; bank contacts 1714173, inclusive, the test relay will not be energized, for the test Contact 172 will not be grounded; and when the slow-acting relay 106ydeenergizes,4 upon the cessation of the rotary/movement, the Etollowing circuit will be completedzpground at G3, working `contact of armature 116 fand the said armature, conductor 77, armature- 123 vand its resting Contact, upper'winding of switching relay 107, upper winding of c frequency selecting relay 108, resting contact of ar1nature128 and the said armature,

testwiperll, test contact 172, conductor 215, lcenter terminal -of terminal'set 111 on horizontalY side of I. D. F.,"s'tran d `of jumper 205, center terminal of set marked 331 ofy idler block group `f7-L1, resistance 220, center terminal `of upper'set of idler block groupk 217, winding of switching relay 13 of line switch C vand the winding of the stepping .12e 1, strand of jumper 2041 centerteminalfof-- the set assigned to pair #l on'the vertical side of the I. D. F., conductor 216, conductor` magnet 15 to battery.- By the closure ofthe above, circuit vrelays 107 and 108 of the vconnector arey connected in series over the third conductor of the called branch.l .with the switching relay 13 of the line 'switch C, and

became the latter relay is energized, Abeing operated only about halt way,"howevenl due to the fact-that the line relay 14; is not energized. As a result, the conductors 218 and 210are disconnected from the :line relay 14 v:and from ground, respectively. At the connec tor, relay 108 is'not energized jbccause of the tact that resistance 220 is included yin the circuit. Relay 107, however, is energized and establishes |locking circuit Jfor itself at Varmature 184, opens *the rotary magnet circuit at its armature 135, connects direct ground to the test wiper l161 at armaturel 188, prepares a circuit for the ring cut-oli relay 104 at armature 132, and. at armature 136 completes the ringing circuit for signalling the called station. The Acomplete `.ringing circuit; over which alternating'current from the l33 cycle generator 'flows out over the lower side of the line Vcircuit and by way oit' line conductor 201 and the ringers atst'ations A and A2 to ground, whence the circuit is completed by ground return tothe other'side of the grounded generator, is not difficult and will"not need'to be traced out in detail. It is understood, of course, that theringers at Stations A and A2 are-tuned to 33 andy 50 cycles, respectively, and that the ringer at station A2 will not yrespond in the present case.

Before proceeding lfurther, attention .is called -to the relay 221 which is associated with idler block group #1,'Fig- 3, there being a similar relay for each of the other groups. This relay is energized in parallel with the switching relay 18 of line switch C both on incoming and outgoing calls vand has the func-tion of short-circuiting .the resistance 220, which operationis necessary yin order to make lall four branches of theline test busy. viheneVer ther-line is called way of one of the 33 cycle branches it is essential that relay 221 should not operate before the switching relay l107 of the connector, as otherwise a false operation ofthe marginal relay 108 might occur, resulting from theMshort-circuiting of 4resistance 220 before relay 107 connects direct ground to the test1 wiper. Relay 221, therefore, is made slightly slow to pull up bymeans of a copper slug or sleeve. It is noted that ythe slow action is required only when the resistance 2,20 is included in the circuit, and atsuch times the presence ofthe resistance assists in producing the desiredresult.v

`When the called subscriber at substation A removes his receiver inresponse to the ringing of his bell, the ringingvcircuit to ground is broken by the hook switch ,and the two line conductors are closedthrough the receiver and transmitter. The return path for ther-inging current is thereby completed over line conductorv202, the upper side ofthe line circuit in the cxchangejthe upper winding ofthe lring cut-oli relay'104,

. and h2 The tehfe'ihihtel at .the tion fie non' ,ehpphed Frith Current en@ 'the exeheee'e' .hehhery to cfoead- To lieg oeeoff relier ie'theletoeieh ized ly @went the barema se with the 33 Ycycle generator orth B eeeooieed ihelleivth, and .hronattteehhs he @relatore 120, .eetahhehee .e `'loehfooa oirout through ite. lower annelies. lei' 1.0.5.It also disconnects `its upper nwindi gan" ringing oo hrehhgehelet-or, et @matures 1 and 121 and at the working icontacts v eel-.hie lerhehlfee oohaeleteefthehel @uit hy .Coeneohne the eoadilota coming line circuit lwith thej'linve' w1 l'- thrash ehe eiedhee of the doable ,relied het. bridge relay 100 Ain the ,usual manner. on'

no such devices arel shown iny thel nt system. A* -K A p The `desired connection has v`now been cuit is shown in 4 heavylineggafiglbeiiiglhgl i 13 ere' deehefehed; thereby ,reetorlle .the selector and vlineswitch'tonormalyalsb ."The selector is olf v.course restored jbyuthefrel'ease magnet :57; whilev the wipers `off the if" switch remain Iwhere they fare, 4and simply `disconnected "by the dieenergizhation of the switchinglrelay l' Y A hlef exrlehetoh will vnew hegiven of the operation of selectiyelyh'signalling other seems kon ehe'i.1e1.efig,.

that station A2 is called,v.the xringefr'atwt station bein `connected .fr brny thefpositiyfze Side of the lheho growth eeethef ringer at station A", but VAbeing tuned td'th 4,0 eyole frequency *When ooifheotedhe' the telephone number of stationris The operation of the vswitches nislthel,same as has been described, except-that since`'the number called is'121, lthe connector Ewwill establish connection with Y thefcalledlinehy way of bankcOntaGts 1.174, 47,17 'fa'nd' F170, the terminal l set on the-hori'zontalsid oftlie I. which is-numb'ered 1241, juinpertlb, and the'50 cycle positiye-terniinalset otiiillei' leo.

block group #iL-this latter set being marked 50p in fthe drawing. YAt the end `of the rotary movement Yor' the switch, when the f slow acting relay 106 deenergizes, a Circuit is'co'mpleted for the relays 107 and 108 of theV connector inyseries'with the relays 221v and 1,3 (these Vlast two beingin parallel),

.which is thelsame Vcircuit as was described l in 'theV case where stationk A- was called eX- krcept that it'does not includerresistance 220.

Itjfollovvsv that since the Vresistance 220 is not included -in the circuit," the marginalrel l'lay 108 atthe connector will be energized at the same time that relay 107 is energized,

'Relay 108 establishes a locking vcircuit` through its lower winding at armature 144,'

l r andat its armature 146 changes the ringing circuit over tothe 50 cycle generator. It Awillbe evident, then, that during the signalling operation 50 cycle ringing current will beV transmitted over conductor 201y of the called line to operate the50 cycle'ringer at A station y A2."

`The ringeij's at 'stations/A3 andA*` are also tuned to the 33 and 50 cycleirequencies, re-

spectively, butare connected trom conductor 202, orthe negative side of the line, to ground.` Referring to Fig. 3, it will be ob# Lserved that there is a reversal inftlielin'e connections between the positive -andinegative terminal sets of the idler block group shown.. Itfollowsthatif either telephone number 131 or 1111 is called, the ringing` current will beprojected out over line concluetor 202 and through the ringers at stations VA Sflild A4 to ground. HWhether 50 cycle Y Aringing current or 33 cycle ringing current isused y.willvdepend onk Vwhether the marginalV relay V108V is or is not energized, and the operation` of this relay depends on ,whether the resistance ,220 isvor -is not included in* -itscirc'ujit, v'as was previously explained.

From the foregoing"considerations it will Y bg Clearr that I` have devisedasimple and eifective party yline system in which the selective ringing is controlled entirely by Vthe connectionsio the called, branches at theY intermediate distributingV frame. It will befevident that any telephone number may be caused to ringen either of the two frequencies to either yside 'of the line simply by connectingtlie'jumper to tlie proper terminalset Vof the idler block group in use.

This makes itepossible to change subscribers fromon'e party line to another, and changey the y frequency and connections of e the ringers, if necessary, without changing-their telephone numbers.

i disconnected from the party line shown andY A QFor instance, and in further explanation Y otthepifocess oi changing a subscribers telephone from onepartynlineto another, if .thegsubscriber at substation Af should change his residence his telephone may be connected to any party line in the new locality on which there is a vacancy. At the exchange the jumper 205 is transferred from the idler block terminal set where it is now connected to a vacant terminal set 'on vthe idler block group to which the new party line is connected, vthe 33P terminal set. beingused in case it is vacant. Assum-V ing that this set is available and is made use of the telephone will'now` be connected 'ors'ervice vin its newlocation without fur- 'K ther change. Incase, however, t-hat the 33P terminal set on the new idler block groupi is in use the'jumper may be connected to any other. set of this group which is vacant and the frequency kof the ringer, the con-` nection of the ringer to the line, or both,

telephone to, the new ringing condition. Y While I have described a certain speciiic embodiment of my invention, vI am aware that Vchangesvr and modications may be made which under certain circumstances may be desirable. For instance, instead of Ymay be changed in order to. accommodate they e the 33 andy 50 cycle ringing current generc ators shown and described herein, gener- Aators'may be used which deliver positive and negative lpulsating currents, such ma-V chines being well known and .in extended use. It will be obvious also' that the prin-V ciples upon which party lines arevconnected up and selectively signalled maybe employed Vwith advantage inftwoparty systems. For a two party system the easiestV method ot procedure is to employ but one kind of ringing current and connect the two stations on each linefrom opposite sides of the line to ground. `The marginal t,

ringing circuit selecting relay at the connector wouldl be omitted, as would also the resistance 220 and relay 221v at-the idler block groups. The wiring ofthe idler bloc;

groups would Abe simpliiied, it being only necessaryto provide for a reversal between Vthe two terminal sets l which take .Y the jumpers coming from the horizontal side In view of the above I do not wish to be restrictedv to the precise form ofthe invention disclosed Aherein but desire. to secure and have protected by Letters Patent allv modiiications of my invention whichmay lthereafter` bev devised, limited only by the Vscope of; the appended claims.

the calling linecan'operate said switch to connect withk any one of said branches, ringing current generators of different fre-i quency, a circuit including said third conductor andy excluding any line or talking iso conductor involved in the connection, and mechanism in said connector selectively controlled over said circuit to select the proper generator to selectivelyY signal a desired sta.- tion on the called line.

2. In a telephone system, a calling line, a called party line, an automatic connector switch, a plurality ot branches of the called line accessible to said switch, each branch comprising two line conductors and a third conductor, means whereby a subscriber on the calling line can operate said switch to connect with any one of said branches, ringing current generators of different electrical character, a circuit including said third conductor and excluding any line or talking conductor involved in the connection, and mechanism in said connector selectively controlled over said circuit to select lthe proper generator to selectively signal a desired station on the called line.

3. ln a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, each branch comprising line and test conductors, a resistance included in the test conductor of one of said branches, means for operating said switch to connect with any one of said branches, selective ringing mechanism automatically controlled over the test conductor of the branch connected with, and means 'for short-circuiting said resistance thereafter to insure the proper functioning of said test conductor.

' 4. In a.- telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, each branch comprising line and test conductors, a resistance included in the test conductors ot a plurality ot said branches,

means for operating said switch to connectv with any one of said branches, selective ringing mechanism automatically controlled over the test conductor of the branch connected with, and means for short-circuiting said resistance thereafter to insure the proper functioning or' said test conductor.

5. In a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, each branch comprising two line conductors and a third conductor, a resistance included in the third conductor of one or" said branches, means for operating said switch to connect with any one of said branches, selective ringing mechanism automatically controlled over the third conductor oi' the branch connected with, and means for shortswitch, each branch comprising -two line conductors and a third conductor, a resistance included in the third conductors of av plurality or' said branches, means iter opcrating said switch to connect with any one. of said branches, selective ringing mechanism automatically controlled over the third conductor of the branch connected with, and

means for short-circuiting said resistancev ing mechanism automatically controlled over the third conductor of the branch connected with, and means for short-circuiting said resistance after the control of said' mechanism has been exercised.

8. ln a telephone system, a party line, an automatic'connector switch, a plurality of branches 'of said line accessible to said switch, each branch comprising two line conductors and a third conductor, a resistance included in the third conductor of one of said branches, means for operating said connecswitch, a plurality of branches of the called tor to connect with any one of said branches, i

a marginal ringing current selectingrelay in said connector controlled over a circuit including the third conductorA ofthe branch connected with, and means for excluding the said relay and resistance from the circuit after the control of said relay has been exercised. l e

. 9. In a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, each branch comprising two line conductors and aV third conductor, a resistance. y

included in the third conductors of a plurality of said branches, means for operat-.

, ing said Vconnector to connect with'any one of said branches, a marginal ringingl current selecting relayin said connector controlled over a circuit including the third conductor of the branch connected with,'and means for excluding theV said nrelay and resistance from the Vcircuit after the control of: said relay has been exercised. n

l0. In a telephone system. a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, each branch comprising two line-conductors and a third conductor, a resistance included in the Ythird conductor of one of said branches, means for operating said connector to connect with any one of said branches, selective ringing mechanism automatically controlled over a circuitincluding the third conductor of the branch connected loo' vwitlwl, andr means :tor excluding. the said mechan sin and resistance rom'the circ-uit after the control of saidv mechanism `has Ybefall exercised! 1 1. In a telephone system, a party line, an automatic'connectori switch, a plurality rif-branches of said line accessible to said switch, each branch comprising two line conductors and a third conductor, a resistance included; in the third conductors oit a plurality oi:'-said.l branches, means for operating' said-,connector to.. connect with any one of' said branchesw selective ringing mecha'- nism automatically controlled over Va circuit including the third conductor of the branch vconnected with, and means'for est cluding the said mechanism and resistancel currentselecting relay included in said circuit, and controlled thereover, andmeans for short. circuiting said selecting relay by closlng said circuit 1n the connector over a new. path.

'1S-.ln a' telephone system, a four party line, an automatic connector switch, as'many branches of said line accessible to said switch as there are stationsonthe line, each branch comprising two line conductors and a third conductor, a resistance included ini thethi-rd conductors of two of said branches,

a cutollbrelayfor said line, means for perating 4said connectort'o connect with any one ofsaid. branches, means in` said connector for establishing a circuit for said cutolffrelay oyer..` the third. conductor of the branch connectedfwith, al marginal ringing current. selecting relay included in saidcircuit. and controlledv thereover, a locking circuit for 'holding up the selecting relay in case thev saine is energized, another seliloclring relay initially Ienergized in. series with the cut off relay, and contacts on the sec'- ond selffloc'kingrelay for .closing the cut on' relay circuit over a path excluding the wind ingsoffboth other relays.l

. 1 4; a telephone system, a party line,

anV automaticy connector switch, a 'plurality olybranchesof said line accessible to said switch', each branch comprising two line. conductors anda third conductor, a resisi v tance. included in. thethird conductor of one. 0i?AV said branches, a cubok relay for conductor direct to the groundedv pole ot" the exchange battery.

la. lnfa telephone. system., a tour partyline, an automatic connector switch, as manybranches of said line accessible. to said switch as there arestations on the line, each branch comprising. two line conductors and Va third conductor, a resistance included'-in the third conductors of two of saidbranches,

a cut-olf relay for said line, means for operating said connector to connect. with. any one ot said branches, means insaid connector for establishinga circuit for said cut-ott relay over theL third conductor of: the branch connected with, a marginal` ringing current selecting relay included in said`circuit, la switching` relay in said. vconnector also included in said circuit, and contactscontrolledby said switching relay for connecting the said thirdv conductor vdirect tov the grounded poleofthe eXchangefbatt-ery'. 16; In a. telephone system, a party line, an automatic connector switch, af-plurality of branches of said line` accessible to, said switch, each branch comprising two line conductors'. and a'third conductor, a resistance included inthe third conductorof one of said branches, a vcut-oftl` relay forisa-id. line, means for operating isaid connectorto connect with. any one. of ysaid branches, means'insaid.v connectorv forv establishing a circuit for. said cut-olfrelay over. theY third conductor of the branch connectedv with, a marginal ringingcurrent selecting relay ineluded.V in Vsaid circuit in said' connector, a switchingrelay in saidconnector also included in said circuit, and, contacts controlled by said switching relay for closing said circuit in theconnector. over. a` path excluding said selecting relay. l

17. InV a telephone system, a four party: line, an automa-ticV connector switch, .as many branches. of said line accessible to said switch as there are stations on the line,

.each branch lcomprising two lineY conductors and a third conductor,l a resistance included Y in thel third. conductor of two of; said branches, a cut-oft' relay for said. line, means lill included in said circuit, contacts controlled by said switching relay for closing said circuit in the connector over a path excluding said selecting relay and its own winding, and parallel lool-:ing circuits for maintaining the said selecting and switching relays energized until the connector is released 18. In a telephone system, a party line, an automatic connector switch, a plurality of branches oi said line accessible to said switch, each comprising two line conductors and a third conductor, a resistance included in the third conductor of one of said branches, a cut-off relay iior said line, means for operating said connector to connect with any one of said branches, means in said connector for establishing a circuit for said cut-oft relay over the third conductor of the branch connected with, a marginal ringing` current selecting relay included in said circuit and controlled thereover, means for closing said circuit in the connector over a new pat-h excluding said selecting relay, and a relay energized over said circuit in parallel with the said cut-ofi relay for shortcircuiting said resistance.

19. In a telephone system, a tour party line, an automatic connector switch, as many branches oi' said line accessible to said switch as there are stations on the line,

each branch comprising two line conductors and a third conductor, a resistance included in the third conductors orn two olf' said branches, a cut-ofi relay for said line, means tor operating said connector to connect with any one of said branches, means in said connector Jior establishing a circuit for said cut-off relay over the third conductor ot the branch connected with, a marginal ringing current selecting relay included in said circuit, and controlled thereor'er, means for closing said circuit in the connector over a new path excluding said selecting relay, and a relay energized over said circuit in parallel with the said cut-oit" relay for shortcircuiting said resistance.l

20. In telephone system, a party line, anv automatic connector switch, a plurality of branches ot said line accessible to said switch, each branch comprising two lineV conductor of the branch connected with, aV

marginal ringing current selecting relay included in said circuit, a switching relay in said connector also included in said circuit, contacts cont-rolled by said switching relay for closing said circuit in the connector over a path excluding said selecting relay, and

establishing a circuit for said cut-0E relay.V

over the third conductor oit the branch con# nected with, a marginal ringing currentselccting relay included in said circuit, a switching relay in said connector also included in said circuit, contacts controlled by said switching relay for closing said circuit in the connector over a path excluding said selecting relay, and a relay energized over said circuit in parallel with the said cut-oit relay for short-circuiting said resistance.

22. In a telephone system, a four party line, ringers at the stations on said line of two kinds connected two from each side of the line, to ground, four called line branches for said line at the exchange,v a third. conductor in each branch,v a connector switch operable to connect with any one of said branches, two rounded ringing current generators of di erent electrical character, selecting means in said connector controlled over the third conductor of an branch connected with to select one of said generators, a relay torthereafter connecting the ungrounded side of the selected generator to a line conductor of the connected branch, there being a reversal in the line connections betweentwo of said branches and the line whereby the selected generator may be connected to either side ot the party line depending on the branch connected with, a

' cutbi relay for said line connected from the third conductor to the ungrounded pole of the battery, and means in said switch tor connecting the grounded pole ot the battery direct to the third conductor of any connected branch after the proper generator has been selected.

2S. In a telephone system, a subscribers line, automatic switches forextending connections from or to said line, a set o nor- 'mal conductors including a test conductorv over whichsaid line is reached when called, a resistance in said test conductor, and means for. short circuiting said resistance whensaid line is busy either as a calling or as a called line.

24. In a telephone system, a subscribers line, an individual switch for extending said line when calling, a cut oli relay for said switch, a set of normal conductors over

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