US1686879A - Automatic telephone system - Google Patents

Description

Oct. 9, 1928.

g N. H. sAUNDERs AUTOMATIC TELEPHONE SYSTEM 3 Sheet -Sheet l NNN IIQI..

FllieMarchtO, 1927 THM N.I H. sAuNDl-:Rs

AUTOMATIC TELEPHONE SYSTEM 3 Sheets-Sheet 2 Imren ur Naz-'man H. Saunders 1,686,879 N. H. SAUNDERS AUTOMATIC TELEPHONE SYSTEM 3 Seets-Sheet 3 Oct. 9, 1928.

Patented Oct. 9, 1928.

UNITED STATES PATENT OFFICE.

NORMAN H. SAUNDERS, F HAOMEWOOD, ILLINOIS, ASSIGNOR TO RESERVE HOLDING COMPANY, OF KANSAS CITY, MISSOURI, A CORPORATION OF DELAWARE.

AUTOMATIC TELEPHONE SYSTEM.

Application filed March 30, 1927.

The present invent ion relates to automatic telephone systems, being concerned more particularly with automatic telephone .systems of the class in which some of the subscribers lines are arranged for loop dialing, while others are arranged for so-called simplex dialing.

The broad general object of the invention is the production of suitable arrangements in an exchange of the foregoing character for use when the simplex dialing lines are relatively few in number whereby the switches operate for the most part over loop circuits, suitable arrangements being provided for repeating the simplex dialing impulses into the loop operating circuits.

In keeping with the foregoing, one obiect ot the invention is the production of a new and improved selector repeater arranged to respond to impulses delivered to it over a simplex circuit (a circuit including both sides of thel callingr line in parallel and a ground return) into a loop circuit tor the purpose ot operating any connector' (or ot` ,i switch, if any) seized by the :elector when the same is operated.

A further object ot the invention is the production of a new and improved counector arranged to respond to loop impulses delivered to it and to complete a connection to subscribers lines in which in'ipulsinpT and supervision are carried on over a simplex circuit.

lnasmuch as the particular simplex dialing lines under consideration at the present time are party lines ot the type in which the different stations are signaller' bv means ot' ditl'ereut codes. it is an object of the invention to equip the loop-to-sinu'ilex connectors wth code .selectors so that a called party-line subs' ion may be signalled by means of the correct code.

A further object of the invention is the production ot' a new and improved relay arramrement for generating the necessary codes for use in signalling the party line substations.

(lne 'feature of the new relay arrangement is that, in a progrlssive counting relay arrangement two impulse circuits are provided, one for operating the relays. and the other for subsequently restoring the relays one at a time.

Another Yfeature of the arrangement is concerned with the provision otl contacts Serial No. 179,443.

controlled by the counting relays for holding various code circuits closed over a relatively long interval of time in connection with an impulse circuit for grounding the code Wires at intervals to produce the necessary combinations of rings.

There are other objects and features more or less incidental to the foregoing. Such objects and features may be understood best after the specification has been considered in connection with the accompanying drawings forming a part thereof.

Referring now to the drawings comprising 1-6, they show by means of the usual circuit diagrams a sufficient amount of apparatus in a telephone system embodyinc: the features of the invention to enable the invention to be understood.

Fig. l is a trunking layout of an automatic exchai'ige of a 100G-line capacity. In such an exchange connectors and one order of selectors are used. It is assumed that there are several hudred loop lines terminating in the exchange, but only 100, or less, simplex lines entering the exchange. A group of selectors. of which the selector repeater SR is one, is provided for handling the alls inconiing to the exchanefe from simplex lines such as the lines of substation A1 and A2. These selector repeaters operate responsive to impulses delivered over simpleit circuits and they repeat loop impulses to any ot the connectors in the exchange.

A group of coi'mectors` of which the connector (il is one. is provided for completing calls to the simplex lines such as the lines of substations A1 and A2. These coin'ieetow` respond to loop impulees received either 'from selector repeaters (such as the selector repeater SR) or from the loop dialing lines such es the line ot' substation A3 after suoli lines have been extended thereto through the medium of f-electors, such as the selector S.

From the foregoing. it will be evident that the selector S. together with the other selectors used for handling calls from the loop lines. and the connector. together with the other connectors arranged to complete calls to the loop lines. are operated over loop circuits including both sides of the calling line in series. i

The simplex dialing lines are of the local aittery type. while the loop dialing lines are of the common battery type in accordance with standard practice.

IHI

Referring now to Figs. 2 and 3, it will be noted that these drawings show in detail the circuits ot the substation A1, the lineswitch LS, the selector repeater SR, the connector Cl', and the substation A2. Inasmuch as the circuits of the loop dialing lines and switches are old and have been well known i'or many years, it is thought nnnecessary to show such circuits.

Fig. l shows the relays of the relay-type code generator, these relays operate to supply grounded impulses to the ten code conductors connected to the bank of the code selector CS, Fig. 3, (individual to the connector C1) and to the banks of the code selectors individual to the other connectors having access to the party lines. It will be noted that certain contacts of the relays ll and E-M of Fig. 4 are not connected together. These contacts connect together and to the code conductor terminals l-l() in the manner indicated in Fig. 5, the contacts in Fig. 5 have been given the same reference characters as in Fig. 4 and are placed so that the conductors joining them do not cross over one another. This arrangement has been adopted in order to enable the connections to be easily seen, as they are somewhat complicated when the contacts are placed in their natural relay order.

The invention having been described generally, a detailed description of the operation otl the apparatus shown will now be given. For this purpose it will be assumed that the subscriber at the simplex substation A1. Fig. 2. desires to converse with the subscriber at the sin'iplei; substation A2, Fig. 3. Upon referring to Fig. l, it will be noted that the number of the line extending to subi-.tation A2 is 320 and that the complete number is S20-5. The digit 5 is the digit used to operate the code selector such as the code selector CS, Fig. in order to place the proper ringing code on the called line. The dash is used to separate the digit 5 from the remaining part of the number so as to make the number easier to remember.

lhen the receiver is removed at. substation A, the usual receiver' and transmitter circuits are closed at theI upper switclrhook contacts. and, at the lower switch-hook contacts, ground is placed on the center terminal ot the ringer through the impulse springs ot the calling device. thereby closing a circuit over the upper talking conductor for line relay 202 ot the lineswitch LSl by way ot the upper coil of the ringer. Line relay 202 operates and causes the stepping magnet 200 to advance the wipers 208-205 into engagement with an idle trunk line in the usuual manner, at which point the combined cut-ottl and switching relay 201 operates, evtending` the conductors of the calling line through the wipers 20S and 205 to the selector repeater SR by way of its incoming talking conductors 206 and 208. Line relay 222 now operates over both conductors or" the calling line and both the lett-hand repeating coil windings in parallel. Upon operating, line relay 222 closes a circuit troni battery by way ot' vertity al magnet 22T to ground by way ot release relay 223. Release relay 228 operates, but vertical magnet does` not operate this time owing` to the relatively high resistance ot' relay 22 Relay 223. upon operating, closes a locking circuit for itself and prepares an o'ierating circuit for the vertical magnet at its inner armature, at the same time opening a point in the circuit of release magnet 228. At its upper armature, relay 223 places ground on the release trunk conductor 20T so as to maintain the lineswitch LS operated after the line relay 202 has t'allen back due to the operation of relay 201.

ll'hen releasetrunk conductor 207 is grounded. dial-tone current commences to flow to ground from the dial tone conductor through the right-hand repeating-coil windings. rthis flow induces a current flow in the calling lint` to inform the subscriber that he may now di; the number.

vWhen the calling subscriber dials the irst u` 25 in desired number, three interruptions produced in the line circuit at the impulse springs ot the calling device. lilhile the calling device olf-normal, the ringer coils are short circuited by the contacts oi" the calling device so as to eliminate the ringer impedance during impulsing. llach time the line circuit is interrupted, line relay 222 i'alls back and opens the initial Iiicuit ot' release reiay 223, at the same time connecting the low round series relay 22tin multiple with release relay 223. The resistance relations between the windings of relays 223 and 22?. is such that relay 223 will tall back eventually it shuntcd continuously bv relay 224%. Also. the vertical magnet 22T operates through the inner upper contacts ot' switching relay 22o and theI inner armature of relay 2233 each time series relay 224i is connected up by rclzy 222. The vertical magnet receives three. impulses and raises the wipers opposite the third level of bank contacts. liuc to the .speed at which the interruptions are produced, relay 223 remains operated. Due to the copper sleeve on its iron core. relay 224, after having operated in response to the iirst impulse delivered to the verti -al magnet through its winding, remains operated until after the last impulse has terminated.

As a result of the operation of relay 224. a` circuit for relav 245 is prepared and is closed immediately upon the ofi-normal movement ot the switch. and a point in the circuit of the rotary n'iagnet 230 is opened, so as to prevent a premature rotary operation. Vi'hen its circuit is closed, relay 225 operates and locks itself to the grounded release trunk conductor at its inner armature, at the same time preparing the rotary magnet circuit at its outer armature.

lVhen relay 224 falls back at the end of the vertical movement, it completes the rotary magnet circuit, at the same time opening the initial circuit otl the now-locked stepping relay 225. Rotary magnet 230 energizes when its circuit is closed and it advances the Wipers 233-235 into engagement With the first set of bank contacts in the third level. Near the end of its stroke, the rotary magnet opens a point in the circuit of relay 225, whereupon relay falls back and opens the rotary magnet circuit. At this point the rotary magnet falls hack and closes a point in the stepping relay circuit. If the trunk line terminating in the lirst bank contact sets is idle, no further rotation taires place and the switching relay operates. seizing the trunk line.

Assuming the trunk line to he husy, relay is operated again through test Wiper 221i, again closing the rotary magnet circuit. The rotary magnet operates again and advances the Wipers another step. rl'his alterA nate operation continues until an idle trunk line is reached, Which trunk line, it will he assumed, is the one comprising conductors 236 239 and extending to the connector C1. Fig. il. VVhen this idle trunk is reacheih switching relay 226 operates in series with stepping relay 225 in a circuit including the grounded release trunk conductor 207, eleventh rotary step contacts 231, interruptcr contacts of the rotary magnet, and the aS- sociated ott-normal contacts. Relay docs not operate at this time owing to the relatively high resistance ot relay 226. Upon operating. relay 226 opens a point in the test circuit and connects test Wiper 234 to the grounded release trunk conductor 20T, thereby making the seized trunk lousy irnmediately; it inserts resistance in the vertical magnet so as to prevent Yfurther operations of the vertical magnet and of series relay 224 when the remaining 'digits are dialed and at its upper and lower armatures it opens the ahoy@ mentioned dial-tone circuit and extends the talking conductors to the line Wipers 233 and 235.

ln the connector ("1. lire relay 302. which is connected to the inner tcritiinals ot the lett-hand repeating coil windings through contacts oi reversing relay 530i. nonv operates over conductors 23V and 238, through the wipers 233 and 235 ot the selector repeater' SR. contacts ot switching relay 226, right-hand repeating coil `u'infings, upper contacts of line relay 222, and the current limiting resistance 221. Upon operating, line relay 302 closes a circuit for the slowacting release relay 2303i. Relay 303 operates and prepares the switch for operation by preparing a looking circuit for switching relay 309; closing a point in the operating circuit and opening a point in the rclease magnet circuit; and placing a multiple ground connection on the release-trunk conductor 237.

lVhen the calling subscriber dials the second digit 2, line relay 222 of thc selector repeater SR 'lalls haelt twice momentarily. .Each time it falls hack, it shunts the release relay 223 With thc series re`ay 224-. Relay 224 and vertical magnet do not operate at this time owing to the imflusion ot the resistance 232 in the vertical magnet circuit. lt may he pointed out that the resistance n'ray he omitted entirely if desired, in which case the vertical magnet operating circuit completely open a'tter the switching relay 226 operates. ln this case the release relay 22? is maintained operated during iuipulsing entirely hy the local circulating current (hrrmght about by its own self in` duction) through its oivn winding and that ot the lou' wound series relay 224. The resistance 232 is included, when desired, so as to cause a slignt current to flow through the :irse/:lated circuit to assist the relay 223 in remaining operated. ller-,h time relay 222 Yfalls; hack, it opens the D. C. bridge across the talking conductors leading to the connector Cl, with the result that line relay 202 falls hack twice momentarily. Each time line relay 302 'lalls hack, it opens the circuit ot the slov.v acting release relay 303 and closes the circuit of the vertical magnet. The vertical magnet circuit.. at the time of its first closure, includes the armature ot relay 3302, normal inner lower armature ot' relay 303, o'ierated, normallyclosed oil"- normal contacts, and the series relay 304. 'l`hc vertical magnet receives tivo iml'mlses. By its operation it raises the Wipers 3l()- the seronfl level oi' hank conries relay 5U-i2 is operated in series certcal magnet and opens a point 'lie in the circuit: ol the rotary magnet, at the same vtime closing a point in the vertical magnet circuit so as to keep such crcuit intact atter the oil normal springs have shitted. aff. they do upon the .first vertical step.

At the end ot the reriieal movement 1e- "ers the al maglll) lil

middle lower armature, normal, of relay 309. In response to the ten momentary closures ot' its circuit, the rotary magnet rotates the wipers 3l0312 into engagement with the tenth set of bank contacts n the second level. Relay 306 is operated in series with the rotary magnet, and, beii'ro slow acting, it remains ope ated throughout the digit. Upon operating. relay 30G, et its upper armature, disconnects test wiper 311 from the test winding ot relay 30S) and con nects it instead to busy relay 305, at the same time opening a point in the lo!` i cuit of the busy relay. At it; lower i ture, relay 30G clo es a shunt around tlre :nsoeiated contacts ot' relay 305 so as to maintain the rotary magnet circuit intact in case busy relay 305 operates during the rotary movement due to tesiy wiper il passing ir-:er grounded test contacts.

Art the end of the rotary movement" busy relay 305 is energized through test wiper 2511 it' the called line is busy. liu this eine, the locking Circuit of rela v 305 is prepared at the upper armature of relay 305, and a further point is opened in the circuity ot the test winding' of relay 309. ll'hen relay .fl-flo falls back under this condition, it completes the locking circuit of relay 305 to the grounded release trunhV conductor Q37. with the result that relay 305 remains locked up until the connector is released. No further rotation Aan take place lre'fause thl rotary me L net circuit is now open at the inner lower armature ot the busy relay. Busy-tone eurrent is placed on the lower 'talking' conductor through the lower armature ot the busy relay and the lower armatures ot relays i107 and 309. The flow of the busy-tone current is through the lower-right repeating-coil winding to battery through the answering relay ltll. The flow of current in tliis'windine` induces a ciuiwent flow in the lett-hand repeating-coil windings which passes berk over the talking circuit to the calling` substation to inform the callin;r subscriber that the desired line is busy.

Upon hearing this toue the callin;a subscriber is expected to replace his receiver and bring about the release ot the coruna ttor.

Assuming now thaty the line is idle when called. relay 305 is not operated when the wipers come to rest on the bank contactsA ol the called line. lVhen relay 300 tallo baci( uuzler this condition, it. completes a connection between the grounded release ti L;

conductor 23T and test wiper lll inrluinag the ripper winning' ot relay il() ll" i nu:

neetion inelurles the uppe relays 305 and andA the armature of relay 309. ll'lirn :i lize is idle. there 1s a battery potential on the test con- :ir-ner tact thereof (encountered in this vale orer prlvate normal conductor 3l-Lt), such hattery being placed on the private normal wuduftor ot the called line through the combined eur-oit and switching relay ot the l (see the lineswitrh LSI, Fig. il the eutotll relay ot the h operate in series, aud the clears the called line of its normal eonuertion with the line relay of the liueswitrl.

.lu the connector (ll. when relay "S00 energizes th oufrh its upper winding.` it coni- :iirefi a ueltloelti lo circuit at its inner lower armature tra'isieri-i the operating" conduetor tit/iu the rotary nrgjnet ot th:- connector to tur operating nu :iet ot the code `sctor til at its middle lower armature; .ae-:ens the test i] uit and contra-ts test wiper lil diz-wthY to ,erouiifl at its inner upper immature.: and aiy its upper ai d lower arma.- tures connects up the wipers 2310 and at:

Y, e l

rent impulsi s are transautted over the onerat nf conductor and through the middle loire;- arrnature olf relay7 2305) to the operatie nizienrt or the code selector. :is a result.y .s es relay I300 1, zin operated throughout and the wiper ot the code selector is advanced lire stesi.

When the slow acti series relay tlb i'alls brel: at the cud oll the ovruiel'it ot the code, seirctor it closes. at the normally closed contacts controlled by its upper armatur1 a circuit tot# rela)v 05 that was prepared by the ott-normal contacts ot the code selector (l5. llelay 30:3 thereupon operates and opens the ogreratroj conduct( at its innerlower arnatire. and it prepares the rireuit for the release nnujuot ot' the code selectrr lii at its middlelowcr armature. Att inner-upper araM the pick-up rela ductor. t this Vthat the pleit-u piclelfp consutlice to state is grounded poi it it 'wi p conductor Iieriodieally vlust before the start ine; ot' zich ode ift-,rind by the cole frereruiir el iowu in Fig. Ll, which code ,treuer-ato:- is s -ted into eqeration upon the oil-normal movement ot any connecte. such :is tell. llheu tl e up conductor is aaiu rrfziuiuled 'l'ixill'i nickthe oeration et relay 230i a circuit for pale-up relay 30u. Relay 'it to .'.i'rourih a the ne tiui^ r' opens the upper at lower talkingv conduclll) tors and places ground on the lower line Wiper and ringing current from the, generator G in the upper line wiper, thereby projecting ringing current out over the called line in accordance with the code assigned to substation A2. The small condenser bridged around the upper contacts of relay 307 permits a suthcient amount of ringing current to leak back to battery through the upper right-hand repeating coil winding and relay 301 to cause a mild ringing tone to be sent back to the calling substation.

lVhen the called subscriber responds to the ringing of the bell in accordance with the code assigned to his station, ground is placed on conductors 313 and 315 of the called line at the lower switclrhook contacts through the midpoint ot.' the ringer coils. lVlien this occurs the answering relay 301 operates through the associated repeating-coil windings and over the two conductors ot the called line in parallel. At its lower armature it opens a point in the circuit of the connector release magnet and closes a circuit through the middle lower armature of relay 305 for the release magnet of the code selector. The code-selector release-magnet now operates and restores the code selector to normal, whereupon the circuit of relay 305 ot the connector is opened at the ott-normal contacts ot the code selector. Relay 305 falls back and opens the code-selector release-magnet circuit, at the same time opening the circuit of the pick-up relay 303. Pick-up relay 308 falls back and disc ninects the ringing relay 307 from the wiper of the code selector.

As a further result ot' the energization of relay 301, the connection between the letthand repeating-coil windings and the windings of line relay 302 are reversed, thereby bringing` about a reversal ot the current llow in the conductors and 233. This reversal is ot no particular utility at this time, but may he used, Vor example, tor giving supervision and tor similar purposes when the call is coming from an operators switchboard.

The two subscribers may now converse with each other, the talking circuits being outlined by the heavy lines.

When the conversation is completed, both subscrilfers replace their receivers. lVhen the receiver is replaced at the called substation, relay 301 falls back and reverses the current supply connections to the incoming conductors back to normal. at the same time preparing a circuit tor the release magnet of the connector.

lVhen the receiver is replaced at the calling substation, the line relays ot the selector repeater and the connector both fall back. and a moment later the release relay 223 of the selector repeater SR falls back, as

weil as the release relay 303 ot the connector C1. When both relays have fallen back, the switching relays 201 and 226 of the lineswitch LS1 and the selector repeater SR tall back. When relay 226 falls back it closes at its inner-upper contacts a circuit for release magnet 228 including the series relay 224. Series relay 224 operates again and reoperates stepping relay 225, which relay extends its operating ground to the release trunk conductor 207, making the selector repeater SR busy during release. lVhen the normal position of the switch is reached due to the operation of the release magnet 229, the off-normal contacts 229 open, whereupon relay 224; falls hack. thereby removing ground from release conductor 207 and deenergizing relay 205.

In the connector C1, the usual releasemagnet operation takes place responsive to the deenergization ot' relay 303, restoring the switch to normal in the usual manner.

Referring now to Figs. 4 and 5, the operation ot the code generator will be described. ln Fig. 4, the relays A, B and C are the impulsing relays, while the relays D-N are the counting relays. lVhen ground is placed on the start conductor due to a connector, such as the connector C1, Fig. 3, moving trom its normal position and closing its olio-normal contacts, relay A operates through the associatated resistance and closes a circuit for relay B, at the same time removing the short circuitfrom around the winding ot relay B. Relay B operates and closes a circuit for relay C, at the same time removing the short circuit from around the winding of C. Relay C operates and places a short circuit around the winding or' relay r.. Relay A falls back when it is short cireuited by relay C. Upon falling back relay A replaces the short circuit around the winding of relay B and opens the circuity to ll. Similarly relay B replaces the short circuit around the winding otl relay (7 and opens the circuit to relay C. Relay C thereupon falls back and removes the short circuit from around the winding of relay A. As will be apparent, relays A, ll and C now recperate. the rcoperation being Followed by the falling back of the relays one after the other in the above manner. This operation continues as long as the start conductor remains grounded.

As will be sec-n from the following part of the description, the entire device passes through a deiinite cycle of operations, there being fourteen distinct,` positions in each cycle. rl`he device as a whole is in position l with relays A-C operated and it is in position 2 when relays A-C have all fallen back. When the relays have all operated the second time the device is in position 3, and when thev have all fallen back the second time the device is said to be in position 4. ln all odd numbered positions of the de- Ult vice, relays A-C are operated, and in all even numbered positions of the device relays A-C are restored. It will be understood of course that there is no clean cut division between the dilterent positions oit the device as regards the operation ot' relays A-C, as they operate and reoperate continuously without hesitation. It will be noted that each relay is provided with a proper collar on its armature end. This is for the purpose of makingr the relay slightly slow in pulling up so as to render the operation less rapid. It will be noted further that when one of the relays falls back it does so because its winding is short circuited. Therefore the relays tall bach rather slowly due to their self induced circulating; currents. lt has been found that the device works best when the relays AMC are afljusted to go through a complete circle ot operations in about one second. Consequently, each relay pulls up and tails hack once per second.

rIhe relays D-N operate as follows: Upon the operation of relay C when the device is in position 1, a circuit is closed through contacts of relays F and Tal tor relay D, the circuit being from battery on the contacts ot C to ground on the start. conductor. Relay D operates and closes a locking circuitfor itself in series with relay` E, but relay E does not operate immediately due to the tact that it is short circuited as long as C is operated. Relay D also closes a circuit for relays H and I in series, whereupon both of these relays operate. lt will be noted that the operating position and the falling-back position of each ot the relays D-N is given in parenthesis above each relay so as to enable the operation to be followed morel readily.

.ln position 2, the initial circuit ot relay D is opened, whereupon relay ll operates in series with relay D, relay D remaining' operated. Relay E closes a circuit 'l'or 'clays l and Cr in series, whereupon relaysl l and (l operate. Relay F disconnects the relay-C impulse conductor from relay D and connects it instead to relay (l. The result is that relay .l operates when relay C is reoperated in position 3 ot the device. Relay J closes a locking circuit for itselt in series 'ith relay K, but relay K does not operate until the device passes into position 4 and the initial circuit ot relay .l is opened. Relay .l remains operated in series with relay K, and relay l( operates.

Upon operating, relay l closes a circuit for relay N through contacts ot relay D. Relay N operates and places ground on the piek-up conductor so as to enable the waiting; connectors to start to ring' at the beginningr of a code cycle. Relay N also closes a circuit for relays L and M in series, whereupon these relays both operate. Relay M opens the relay C impulse circuit, and prepares an impulse circuit through the upper contacts of relay B. Relay M also closes circuits shown in Fig. 5 so as to start the delivery of the ringing codes. The generation ot the codes will be discussed atter the description ot' the operation ot the relays has been completed.

lhen the devices arrive in position 5, a short circuiting impulse is delivered by relay B to the junction ot relays D and E. This impulse is a ground impulse troni the grounded startv conductor and its path includes the upper armatures ol relays M and B. YWhen the ground potential is delivered to the junctions ot the winding ot relays D and ll, through an operated armature ot' relay ll, relay l) is short cirtaiited and 'falls back, oiliening the initial circuit ot relays H and l. Relays ll and K. however remain operated in series with each other owing;` to the tact, that their circuit is closed through contacts ol relay ll. Relay D also opens the circuit ol relay N, whereupon relay N falls hack and terminates the pick-np impulse, at the saine time opening' the initial circuit ol' the now-locked relays L and hl.

With the device in position t5, the impulse delivered through the contacts of D is terminated, whereupon relay l@ falls back, having' been maintained operated alter the talling' back ot relay l) solely through the upper ccnta1 ts ot relay ll. Upon 'falling back. relay ll transfers the relay B impulse conduc` tor through an operated armature of G to the junction ol relays l? and Cr. telay E also opens the initial circuit of the nowlocked relays F and C..

From a consideration ot the foregoing description and trom an inspeition ot the drawings it will be apparent that relay Gr falls back in position tl; that relay H falls back in position l); that relay .l 'falls back in position lt): that relay' l' 'falls baci; in position ll; that relay li falls hach in position 12; that relay L 'tails liacl; in position 123; and that relay hl tails back in position ll. lt will be apparent also that relay lil 'lalls hack responsive to the deenergiffzation ot relay l, and that relay C is s ll operated when relay ll falls lz-aclr. 'lliafl' being the case, position l ot the device Ytollows iinmediately after position 1l. as relay lil opens the l-relay in'ij'mlse circuit and recloses the C-relay impulse circuit. lllhilo relay C ls fallingT lz-acl, a'tter its circuit is opened and its short circuit is roik'ilaced by relay B, rclays l, ll and l operate again in position 1 ot' the device, following' which the aoove described operations ot the relays talre place in the next cycle.

Referring? now to (l it will he noted that the codes, placed on the ringing code conductors 1410, consist ot various numbers ot long and short rings. rllhe long rings are lltl lio

iroduced from the steadily grounded conductor 402, Fig. 5, through armature M2 ot relay M, While the short rings are delivered fromconductor 401 through armature B1 ot relay B and armature l o1 relay M. The code conductors will now be considered in order and the way in which the cod es are placed on these conductors in accordance with the table shown in F 0 will now be explained.

Considering the code conductor 1, the code placed on this conductor consists ot one long impulse. This impulse is started when relay F falls back in position 7, While relay l is still operated. The path ot the impulse 'from the `rrozunled conductor 402 includes armature ll, armature l2, and armature lt. This impulse circuit is opened at arinatures l2 and l4 when relay l falls back in position 10, and it is not a5Y iin closed until the position 7 is reached in the next cycle of opera-- tions.

Considering` nonv 'the two short impulses placed on code. conductor 2, theser impulses are delivered from the impulse conductor 401 under the control el nature lh Conductor 2 connected to conductor 401 through armature G when armature M1 operated in position and it remains so conuected until relay (l falls bach` in position 8. The tirst short impulse is delivered to conductor 2 when relay B operates in position 5, and the second short impulse is delivered vvhen relay B operates in posit'on i'. Relay (l tells back and disconnects conductor 2 at the beginning ot' position t.

Regardingconductor 3. the three short impulses are delivered to this conductor in a manner similar to that described in connection with conductor he dill'erence being;1 that the connecten between oiuluctors 401 and the impulse conuuctor 23 includes armature V13, which remains operated until the device ooes into position l0. its a result, code conductor il receiref-z an impnli-ze in position 5, another in position T, aml another in po.L on 9.

Cons'dering` now impulse conductor 4, the code placed on this conduce' is i'or short impulses. lt Will be nctcu that code conductor 4 is connected lo the impulse conductor 401 through contacts lil and l@ until relay K 'tails bach in p" 1*) Accordinclv. code conductf 'eceives an impulso in each of the po, ions 5, T, 9

and l l. Considering; code conductor the code ylaetd on this conductor is one lone` pulse and one short pulse. `he long pulse is di livered Vtrom conductor 402. starnng in position 4 when contacts lil? is close l. and contii'uiiutr until position S is reached when the pulse circuit is opened at arnriture (l2, terminating! the long pulse. lllhen relay ll falls back in position 9. a connection is closed from the impulse conductor 401 'through armatures K1, H2, and I1 for placing the short pulse on code conductor 5. This short pulse terminated at the end of position 9 upon the falling back of relay B, and the path between conductor 401 and code conductor 5 is opened at armature Il when relay l falls back in position 10.

Considering code conductor G, the code placed on this conductor is one long impulse and two short impulses. The long and short impulse placed on code conductor 5 while the device is passing through positions 4-f9 is also placed on conductor G, as the two conductors are connected together at armature l1 during such positions. After conductor 5 disconnected `from conductor 6 at armature I1 at the beginning of position l0. the connection between conductor 6 and conductor 401. including armatures K1 and il: remains until it broken at armature Kl `when relay l falls bach at the beginningof position i1) 'l`he second short impulse is ulaceil on conductor 6 when conductor 401 1s rounded at armature lll in position 11.

l`ou;-;iderine now the code placed on code conductor T. this code tWo longT pulses, the

pulses bene' place-d on the conductor in positons 1-9 and in positions 11-13. The first puise is placed on code conductor 7 trom conductor 402 tlirougrh armatures F1 and I2 when relay l`I` tails back at the beginning of p ,..ition i' while relay I is still operated. lelay l falls back at the beginning ot' position 10 and terminates this impulse. At the beginning; ot position 11, relay J falls back and 'starts the second long' impulse at armatnre ill. This second impulse is terminated when conductor 402 is ungrrounded at the beginning of position 14 by the falling back ot relay hl.

{lonsidering code conductor 8, the code on this cond uctor is one short impulse and one lonsr impulse. The short impulse is placed on conductor S through armatures E1 and L2 while the device, is in position 5. The connection between impulse conductor 401 and code conductor 8 is closed at armature L2 when relay L operates in position 4. lVhen relay l'l l'alls back in position 6, code conductor 8 disconnected from impulse conductor 401 and connected to code conductor 1, with the result that it receives a loup impulse in positions 7 9 at the saine time that code conductor 1 is receiving its single long impulse.

Regarding code conductor 9, it will be noted that conductor 9 is connected to conductor 8 through armatures M3 and J2 until relay l tails back at the beginningV of positionI 11. at which time the short pulse and longpulse have been placed on conductors 8 and 9. The complete code tor conductor 9 is one short pulse and two long pulses. Accordingly, conductor 9 must receive a second long' pulse through armatures J1 and J2.

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This second long pulse is ixcceivcd in positions 11-13, at which time it will be noted tliat conductor 9 is receiving its second long pulse at the same time that conductor 7 is receivingr its second long pulse. tlie pulse on botli conductors being terminated when conductor O2 is ungronnded at illE at tiic be- ;inniig oi" ncsition 14.

Tlic colicA on code conductor l() is tvv-o sliort pulses and one long pulse. Conductor lll is Connected to impulse conductor lill tlircuiii armature (l1 in position 2 ot tlie device. and it remains so connected until tlie lvicc reaches position 8, receiving;` a sliort nilse in position 5 and anotlicr in position 'i' ,ilicn relay H tall.4

i position 9, a connection is closed at armaiire li' tlirougfli armature K2 betivecn conluctors l() and lof, 'l`liis conniciiicn rciiiainz-y closed until reay l falls baclir at tlie beginning ot' position l2. cai'isiiri 1i lone; pulse to be placed on conductor l() in positions 9` l0, and 1l.

lilliat l claim is:

l. ln an automatic telelilione system, a telei'alione exchange terminating subscribers lines, a large portion ot said lilies beine' arranged tor loop operation, vfliilc only a small portion ot the linesI are arranged for simplex operation over tlie tivo sdes ot tlie line and a `ground return. selectors and connectors in said eI-:cliano'e tor coiiiijiieting calls initiated on loop lines, said switches being operated according to tlie loop s nein el control, and selector repeaters in said eX- cliang'e for extendingI to connectors connect'ons originated on the simplex lines, said selector rcp-eaters being arranged to operate over a simplex circuit and to repeat loop impulses to tlic connectors.

2. In a teleplione system, a telephone exchange terminaling, subscribers lines arranged for simplex operation, a connector switcli liavimf; access to suoli lines, said connector switch being arranged to respond to die loop system of control, a revers'ng;` relay in said connector tor reversinga tlie current snpply connections to its incoming talking conductors, and a circuit for said relay including' tlie two sides of any called simplex line in parallel and a ground return.

In a telephone system. a connector siv'tcli liavinp' access to subscribers" lines, means for operating' said connector to extend a connection to a line` a party-selectin;r device, means effective during' tbe setting; up of a connection for operating said device to select tbe wanted station, means tor applyinsr signalling current in accordance with tlie setting of said device, and means for terminating tlie application ot signalling current upon tlie response of the subscriber at tlie called station by releasingr said device.

4. In a telephone system, a connector having access to subscribers lines, means for baci: at tlie beginning` operating` said connector to extend a connection to a lne, a party-.selecting device, means tor operating said device in accordance ivi tli a party digit in tlie number to select tlie station on a called line to be signalled, and means for termnating tlie application of f-figgnalling current upon tlie response of llic sili-1i.il er at the called station by rcierisiiigv said pai-ly select ine' switcli, tlie operatingv means ot said sivtcli being again responsive tbe calling),l subscriber dials anotlier digit` aller ilic called subscriber' lias replaced bis receiver to make anotlier station selection and cause a further applicalion of ringing' current to be made to tlie called line.

In a telephone system, an automatic teleplione exchange comprising selectors operated according to tlie loop system ot iiitrol. selectors operated accor-dim.'` to tbe siiiiplei; .s stem ot control, all of said sinipleX-opei'ated selectors being adapted to repeat impulses accori'ling to tlie loop system of control, a ililnrality oil connectors operated according' to tlie loop system of control ac 'e: .ile to all oli said selectors, lines arrancjcd for loop operation accessible to some ot said connectors, and lines arranged for simplex operation accessible to otlier ot said connectors.

t3. ln a telephone system, a selector operated over a calling subscribei"s line on tlie loep system ot control, a selector repeater operated over a calling subsciibers line on tlie simplex system of control, the tall'ngj conductors ol said second selector being in non-coiuliictive relationship Witli the talking conductors ot' tlie calling line, a connect-or accessible to either of said selectors. said connector including means maintained operated over a calling line wiicn tbe first mentioned selector is used for maintaining tlie connector in operated position. and means ctlective it said selector iepcatcr is used tor also maintaining; said first nanicd means operated to prevent tbe release ot tlie ci'innectoi'.

T. ln a tclcplione s.y iitem. a selector operated over a calling subscrbei"s line on the loop system. ol control, a selector repeater operated over a callinc; subscribei"s line on tbe simplex system ol control, tlie talking,Y conductors ot' said second selector' beingr in iion-ci'indnclive relationsliip vvitli tlie tall;- ingr conductors ot a vcalling` line, a connector accessible to eillicr ot said selectors, said connector incliulingjf,h means maintained operated over a calling' line vvlien tlie tirst nientioned selector is used tor maintaining tlie connector in its operated position, and means etliective it tlie selector repeater is used for also maintaining said first named means oprated to prevent tbc release ot tlie connector, said last named means being in tl'ie selector repeater.

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8, In aA telephone system, a connector operated on the loop system of control and having a relay maintained operated over a loop including a calling subscribers line for controlling the release of the connector, a selector repeater having incoming and outgoing talking conductors in non-conductive relationship with each other, said selector repeater beine` directly controlled over calling subscribers lines and having access to said connector, and means in said selector repeater tor controlling said ist named relay over a circuit excluding a calling line.

9. In a telephone system, a connector operated on the loop tem of control and having a relay maintained operated over a loop including' a callingline Yfor controlling the release of the connector, a selector repeater operated from calling subscribers lines on the simplex system ot control, and repeating impulses under the loop system, having access to said connector', and means in said selector repeater for maintaining said relay in the connector operated over a circuit excluding a calling line.

l0. A telephone connector switch having incoming talking conductors, a source of potential connected to said conductors, 'two outgoing talking conductors, each terminating in a wiper, a relay for rerersng the potential connected lo the incomingr talking conductors, said relay being controlled over a circuit including both of said wipers connected in parallel.

ll. In a telephone system, a connector switch, a plurality otl lines accessible thereto, means for directively operating said conncctor in accordance with two digits ot a telephone number to select a desired line, a party selecting device, means controlled over the connector for operating the device in accordance with a third digit of the desired telephone number to transmit characteristic ringing current to the called line, and means effective responsive to the answering of the call for releasing the device thereby stopping the transmission ol the ringing current.

l2. In a telephone system, a connector switch, a plurality of lines accessible thereto, means lor directively operating said connector in accordance with two digits of a telephone number to select a desired line, a party selecting device, means controlled over the connector for operating the device in accordance with a third digit of the desired telephone number to transmit characteristic ringing current to Vthe called line, means effective responsive to the answering of the call for relrasng the device thereby stopping the transmission of the ringing current, and means cliccati rc responsive to the termination o? the call by the called party for reestablishii'igl an operating circuit for said device under control of the calling party, whereby the calling party may again reoperate the device to recall 'the called party.

i3. ln :i party line telephone system, means including an automat/c connector switch and a party selecting device individe'al thereto for extending a connection to a yired party line and t'or signalling the detired party thereon, means for subsequently #elcasing said connector switch, and means eiiective before the connector switch is released :2nd after a desired party has been signalled for restoring and reoperating the party selecting device to again signal a desired party on the called line.

ln witness whereof, l hereunto subscribe my name this twenty-eighth day otl March, D., l927.

NORMAN H. SAUNDERS.

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