BE467952A - - Google Patents

Description

       

    <Desc / Clms Page number 1>
 
 EMI1.1
 



  "\ i1J: .feÓt: i.oxiY \ em.er.ts a.ux dil.7]? oYitj.f8 .¯tééJ)! 1o!, j..a \ .J !. If
 EMI1.2
 The present invention relates to telephone devices and is more applicable: part icnliè: cem8pt to rural telephone networks comprising a main exchange by means of which all incoming calls are routed.
 EMI1.3
 enter the network or leave the network, as well as a certain number of external rural exchanges serving either
 EMI1.4
 functioXl) 1emnt in tandem, or at -L'oActiorinemert e: n central te: cm: J.J'1al.



  In the network of this kind, the various cen- / 7

  <Desc / Clms Page number 2>

 
 EMI2.1
 external traps. are usually so small that a 24-hour manual service becomes extremely expensive and inefficient, that, with regard to the possible installation of an automatic defect, the :, i : co: fl 1, 1 t 1 n; n reali- sic d.?n .. '' ;. the subscriber lines are often much inferior;.: or minimum required for a r-I Y-, 03 'to. ak 1 #: 6 J: 1>; a.n t der. : I, m "':' 1Ùf:. :: i.OY'O 0 v e r the central automatic equipment.

   A solution. Which already. summer pr020 ;;!: e e c on x 1 x t a laier the devices: 3- reils (the, ;; subscribers had manual type, and t to provide a bouipernent;, <1; .1 s r ,; o .t fl. <iu e to i n le, ':, i different centr'jux e:;. l <? r 1 <-. ii: r 1,, this team being controlled in an & emi-a.utoi'i) atic manner by an operator in the main exchange at.lÀollel the central t. :.; .. t é i, 1 +. ixT. z> i> o r> subordinates, this automatic equipeaent é t a, i?> t g; , <i i; c so a. & i-.urer, e under the effect of an f;: igY \ 8.1 from
 EMI2.2
 of one. subscribers, automatic connection of this correspondent to the operator of the main exchange.

   With some
 EMI2.3
 F. i .. :::; o;:; 1 t 5. i>: to. this kind, each kind of call going through a small exchange of the. i? é 1: e: at the request of the intervention of 1) er0 ,. trice, what f ' <: 1.,; E d.e8 device): 'cut-off e. fl. e circuits which eo "'t complete !. The. others <.: i Y> c o;> v é: <.i 1. é ..:> -, .t that we can.t do 1 <> 1 tsp. > r Mount slowness el 'ét Ç) 1) 1 i 8 $ ome "" .t to, <; communications and;,; limit which are .t or ;; ". fli le [; <; ie <; e a i # ii of this record 91. '. point of view of their development.



  The main object of the present invention is r> c oF. <5 1. 1. L ", 1 # =. Resli -.-. Ation of a telephone device perfects con'c'er'a.nt for the i + rég 1 on rural and which 1;:; o S, a lot fold <. 5.,; j; 1 and 'much more direct than e 1; 1: r? ; ' >. = ù a ià .: r 1, central;:. <. ,; i ±. - s. u: t o>; ,:. <i; j. , ¯ ii i e: of the type above ... u .. described, and which functions z -u <. vs : <',' 1; nj :, o x. t which e 1.j, g: - <c1 'abo! "t'.é .S x m f; <1,. a ;;; m e; fl 1Jo1 "" 11 "\ e to allow manual operation, 0 e; <; u: t iF 1 s:?, ini; i e iJ 1 .: <>:.;

     to allow key to command i maneuver or fall. "':; i'elai & r. é 11, n un cc.ntra.lt Co (If Oi.)' {J [jm.E: i1t to one characteristics!:! from pr 6 -

  <Desc / Clms Page number 3>

 According to this invention, use is made of the automatic selection system which was described in the patent application filed in Belgium on August 20, 1946 under number 362.823, in which there is no need to receive pulses emitted by a device. dial or similar signals from a calling station, the selection of any one of the lines existing in a number being initiated by a signal from a calling station, and continuing to that it is terminated by another signal from the calling station when the desired line is found,

   the progress of the selection maneuver being continuously indicated to the calling station, for example audibly. The calling party is preferably indicated each step taken by a selection switch on the exchange, by means of a tone pulse applied to his line in the exchange.



   This system is used in the various external exchanges of the rural telephone network, and its use allows the establishment of local calls without the intervention of the operator of the main exchange, which eliminates the latter from a significant work, saving trunk lines and by making the local exchange more independent from external conditions. A local call can thus be made even if the outgoing trunk line is not in good condition or if it is occupied by another call. In cases where manual subscriber telephone sets have already been installed, the modifications required to these devices are extremely small and mainly involve the addition of a control push-button on each device or next to each device. apparatus.



   For local calls, a calling subscriber removes his earpiece and presses his push button to initiate the call.

  <Desc / Clms Page number 4>

 
 EMI4.1
 f>: .-; c t 1 o: r> ... <.>> i; e ii of an ele.ctic'n switch in .. the local exchange. Lor & that this'. switch performed 1 desired number of pa, which e 5 t 1>; <1 1 q i; by number <:; to e i ioe,> i <iL 1: 1, o: <' <tone received, we stop the fOfict iOn, l8ïllE, nt of i '1 n t <; i <:;. iii; - tor E 12.ch <: read the push button. The C? Ù 5 T <± t É Q 1 <", (1 1 <1 ± 11 ie renew e at the same f¯1.ÇO'l> ;. 'i must get 1'> Ôm 1> 1, 1; 1 o; <of a é. e c o> ' <d, é i é ùi e; =. d'n number of the c o r x = e ;; p o: " <to. not . <i t <1 e i;> i ;. > i ô. é, any ma-> i c e i i v i :. callback Ori d'ava: r! C0r! 1crt 2at; a 1.) é1.

    . at.; x .t <> i:; at 1 ç ix of the switch which must be accomplished <> 1; .p x. é 16 e r é 6 1 a, c e 1 r, 1 - t 1. i taking place: i.v a> it the execution of the z e c o: r> d. maneuver of i; <'i c a t 1, o r. and emission c o r e k; j: <o; '1 d?, nt of a tone. The co: r ..: CEH.1l 'YJào.nt deùj8, ncleu.!' <'3. ainfi> i 1 a. This is it. desired line, and e: s.g; i; 1 t? , when the convereetion ee terrfiinoe, 1. g, commm '"iic8t 10) 1 s cuts e qu an. d. i' a.b onn hangs up.



  For key; calls, going outside the ce.ntx = to.l 1. o c ;: <1, a 1> ¯1J o; n;> requestor selects a 0 0 -if c determined, of a higher order, preferably, than any of those required for local service, to su 1 - té what a signal indicating that it is t <1. 'Gn external communication to the local exchange 6 "t automatically transmitted v cz forward from the local exchange to .. the operator who x finds the main exchange to which the local exchange is subordinate, this pigeai being repeated aut01} atj. (. lUtmeYlt in any tandem exchange that may be between the local exchange and the main exchange.

   The calling subscriber then indicates to the operator the desired number outside the local service, and u-i this number is that of a subscriber who i e <; 1> "ù:> '> C li = Ù 1> c .i? An exchange which is on the initial route, the attendant presses 5 with the call card dan'.:, A. .C1, = k associates with 1 1, 11. 5 g <= <arrival and selected Y.'rogre.iveent in the ;;. ei; <i '' '' ve '!,'!:. e to establish 1,2 a - T e le e c o r. <. e> x,> o n - da! t delirium. When 1 'o z> é r? al r S. c reaches the desired subscriber, TLn J 1 1; " <: is sent to, from its position for US8urr 1 ' <. ± "o ō

  <Desc / Clms Page number 5>

 Communication between the calling subscriber and the called subscriber is terminated, and the operator can then listen to the conversation to ensure that the communication has been established satisfactorily.

   When it withdraws from the call, the connection going to the junction point is cut, and the cut of the established call is then subject to the control of the subscribers who have been put in communication.



   With the circuits arranged in accordance with the present invention, the selection by the operator can be carried out in the reverse direction and through the initial route, although this way of operating is not new. in itself, in a much more reliable manner, as will be shown by the following description which will bring out yet other new characteristics of the present invention.



   The description which will follow in. Looking at the appended drawings, given as non-limiting examples, will make it clear how the invention can be put into practice.



   Figure 1 shows the line plan of a typical rural telephone network.



     Figure 2 shows schematically the characteristic connections of one of the antennas of the array of Figure 1.



   Figure 3 shows a typical arrangement of lines in a tandem central station such as the one designated RE in Figure 1.



   FIG. 4 represents a line circuit for a subscriber connected to a terminal exchange or a tandem exchange, this subscriber being provided with a magneto telephone set.



   The figures) :! 5 and 6, when placed next to each other, together represent the circuits of the

  <Desc / Clms Page number 6>

 
 EMI6.1
 common pemer.t necessary for each of <; automatic central exzan: i. ', 1 or in tandem of the network, this equipment being used, to allocate for use the different connection circuits between locatzj: researchers and the connectors of which each equipment of these ee: <; tra, i = <eet provided, and to produce., tones of dreams and other ::, tones, as well as the (.; impul-; iO "8 of comI / c: 3.ge, I-e <= figure;: -! 7 and 8, when :: placed next to each other, represent the c.et3lE;

   of a link circuit ,,: or, between a finder and a connector of u '': 'automatic exchange capable of:'), 8; JUl't: r the service of nine subscribers and CLC ': i: E : Y'vi'r 'a junction line, an exchange of this dimension i> io = 1 being atili16 only as a terminal exchange.



  The figures> 1 9 and 10, lorNclta 'or: leu c1.iuyo (> e next to each other, together represent the circuit of the incoming selector of a terminal exchange'.
 EMI6.2
 Figures 11 and 12, when the dinpoae is next to each other, together represent the circuit of a
 EMI6.3
 1iah, we enter a finder and a connector of an automatic exchange capable of providing the service of 42 subscribers and seven trunk lines, this exchange being able to be used either as a terminal exchange or as a tandem exchange,

   and including scanning possibilities depending on the system
 EMI6.4
 says the B.X, Lex figures 15, 14 and 15, when it ::! placed next to each other, represent the circuit of a selection
 EMI6.5
 input of a tandem exchange, while Figures 16, 17 and 18, when placed next to each other, show the circuit of a repeater of a central exchange. tandem.
 EMI6.6
 



  We (nl: Dl) Ofer8 that the main exchange to which the external exchanges are sub'ordinated and a manual exchange, TY1.?i. it could, of course, work, <1;: 4 vi'lt a normal automatic system with regard to local calls,

  <Desc / Clms Page number 7>

 all calls intended for the rural network being routed through an operator of this exchange.



   Regarding, now, the operating mode of the device, its technical operation is new, but it is not that the operator of the main exchange is aware of it, so this operator will adopt the same procedure for establishing a call as in the case of a normal semi-automatic exchange.



   As stated above, all local calls are transmitted automatically by the calling rural subscriber. All calls leaving the local network and passing through several exchanges are established under the supervision and by the intervention of the operator of the main exchange, these calls being virtually independent of the local organs of interruption of the rural exchanges, so that the device can rightly be considered to have two entirely distinct characteristic modes of operation, namely: a) automatic selection controlled by the operator with inversion if necessary. b) the operation of the automatic rural exchange without a dial on the individual stations.



   In other words, the rural exchanges can be seen as independent units that intervene in one. communication network controlled by an operator.



  The two parts will now be described independently of each other, starting with the communications network.



   If we first refer to figure 1, we see that the main exchange to which the external exchanges are subordinate is designated by P, and that this main exchange is connected to a network of main exchanges by means of lines like line -10. The tandem exchanges which are

  <Desc / Clms Page number 8>

 climb in one of the rural network lines designated exits
 EMI8.1
 by RE and RD, while the cent1 'at the ends are designated by RA, RB and RC.

   
 EMI8.2
 If we consider rnainte- "8.nt a call that enters the rural network from the P exchange and if we refer to Figures 1 and 2, we see that each trunk that arrives in a rural exchange (: ends it on a selector
 EMI8.3
 entry ;; l1r the banks of which the lines of local subscribers are waved and also all the junction line8 t.> o: ct ')! îte8. In the case of C0Jîtro, ux in tandem, the input selectors are of the vertical type turned '' '' t with two electro-am¯ ta, with what is called the recta drop system, i? Giila .i- re, while in the case of terminal exchanges, the same purpose of so-called uni-cclector koelects is used.

   In general, the levels !: 1 raz 6 or their equivalent on the banks of:; c: lectet: input rs corre- sponding to the uni-selector are assigned4, to subscribers, and levels 7 to 0 at the outer junction lines. In this' '' tandem frame, we assign to
 EMI8.4
 a.borxré. local two-cipher numbers from the 11 60 series, while in terminal exchanges one uses
 EMI8.5
 number! :: is a single digit of the 0.



     Consequently, if we consider figure 2, we see that when we push the O / G card corresponding to a, the
 EMI8.6
 11 '; "' -, e ::; oat¯wte, the operator had connected to the input selector of the rural exchange in tandem RE. By the, selection of one of the number 1 to 6> iivi of a second digit, the attendant puts herself in communication with a subscriber of certx¯, l R1;. 8 if an 8 or a 9 is selected, a sweep maneuver is triggered by the selector and the oCc'Ul) 8, tion of a junction lib "e with the central RD or RA, as the case may be.

   This junction lines ',; E' terminate èl.e again on dreE, :: J8input driveb which can be set i.; Ur one qtzelcoit, tz, E: s. subscribers of the exchange in question, or, in the case of the central RD, it is possible to select

  <Desc / Clms Page number 9>

   press 9 or 8 which gives access to the RB or RC exchange. Consequently, this type of call involves the introduction of a file and the normal selection of the subscriber's number.



   With regard to calls originating from a rural subscriber and intended for the operator, then to be transmitted to another line of the network or to an exchange outside the network, we. uses in all cases the number 7 which is assigned to the operator, and when the latter receives this signal in accordance with the aforementioned automatic selection system, the call is immediately routed to the manual exchange P to which the exchange in question is subordinate . If we consider for example the central RO, we see that when transmitting a relay OG is actuated in this central and the line with the central RD is busy. In this last central, a relay
OG is activated and a junction line with RE is occupied.



   This operation is automatically repeated in RE, and a call signal is given next to the I / C answer jack in the exchange to which the exchange in question is subordinated. If, when entering an answer card, the attendant realizes that the call is intended for another line in the network, she inserts the call card into the appropriate output jack. , and it selects the number in the same way as already said above for the incoming call. If the call leaves the network, it is transmitted over a line such as line 10 of FIG. 1 in the usual manner.



   In the case of a call originating from a rural subscriber and intended for another rural subscriber connected to another exchange, but attached to the same line of the network, the operator receives the same signal as in the previous case. When the desired number is on the same line, the attendant inserts her call card into the multiple output jack corresponding to the trunk line through which it is activated.

  <Desc / Clms Page number 10>

 
 EMI10.1
 pel been received, iA continuation of quofl. ii; 7 is sent automatically to produce the reverse on the input selector at the far end of the trunk line.

   The call is then routed by selection in the same way as in the previous case, the maneuvers) not involving any differences for the operator in either case.



   Thus, if, in the previous example, it is a
 EMI10.2
 o.bOYlr10 du cen: tifla, the RC who calls, when the 7 is made, the call reaches the operator under the effect of the e> here: ta: µio> i à.e% different OG relays of the circuit. When the attendant inserts her plug into the multiple jack, the OG relay of the RE central unit drops, thus connecting the attendant to the input selector.
 EMI10.3
 



  If the apà> e1 is intended for the central. 1 RA 01 rqz "" the operation of the a-reader is done in the manner îia; JitiAe1ie; .ùa.i; .S ioi one has selected the 8 indicating the central RB oii RD (a call for RC I; J $ cOn1j? Lète1: '. <Jit locally automatically), the OG relay from the central is a, ctio.n.> Jé: again, so that the successive trains of pulses are transmitted back by the line through which the call was launched. As soon as the OG relay of the central unit is actuated at. again, the corresponding relay from the central RD falls by connecting the line in this way to the input selector of this central.



  This consecutive reversing maneuver can be performed as often as necessary.



     When the delirium subscriber's call has been made
 EMI10.4
 (the "not completely, the operator maneuvers aa key of igna- This has the effect of connecting the & two 1.bonn8.S by the shortest route, and have the call provie-'if by example 1 of the central? C and is intended for the central 1 RB, the operation of the key causes 1 2, Dli of the. coml] lJ, nicot1o ' <'\ shown in dotted lines in the central RD.

   A1i.B8i long q1 ('o' "lai!:." E answer and call cards e; J: fIn.r <cée>, the operator continues to be linked with the. subscriber who are in

  <Desc / Clms Page number 11>

 communication, in order to be able to ensure surveillance. When she is sure that the conversation is exchanged in a satisfactory manner, she removes the cards, which cuts off the communication lines in the central RD.



   If the attendant wishes to cut off the portion of the call that she set up by selecting, she removes the call card, leaving the answer card in its folder. This has the effect of restoring the previous conditions, and the branch again through all OG relays operated on the calling subscriber. By reintroducing the call sheet, the conditions necessary for selection are re-established.



   As regards, now, the devices provided for verifying the number of the calling subscriber, which is necessary given that for all calls outside the local exchange the operator notes the amount of charges, a calling subscriber who triggers such a call will therefore indicate its own number. To verify this point, the attendant inserts her call card into the multiple jack and selects the given number, as if she wanted to establish a call with this number.



  The succession of reverse selection pulses which has already been described is transmitted in exactly the opposite direction to the calling subscriber and only uses the trunk lines through which the communication has been established.



  Alternatively, the attendant can simply reverse a verification key which provides the same necessary control effect in rural exchanges as inserting the call card into the multiple jack of a calling line. a rural network. If it reaches the calling subscriber, it hears a special tone which indicates that the number which has been given is correct. This tone can only be provided by selecting back the particular subscriber who is on call.

  <Desc / Clms Page number 12>

   demand train? the operator, and we can get it even
 EMI12.1
 neither the subscriber is part of a group of the type called P.B, XX mentioned above.

   To end a verification call, the attendant withdraws the call record or returns k, -3 ni "verification.



  , Z; n what OO '[' 1Ce1. ':.' le le ':! rural automatic exchanges, d1,1 :; ' the devices tl ', t101Ç1: .B :. of the subscriber, that we S1l'J; octa, dana la. sequence of 13, denoription of $ circuits, $ tre of the magneto type, a key é = 'a' rJOuOïl..i) py'1; -., t0: 1. "C and cl, a single break, COixx ' 4-C: L: L'Cll: Lte l) O.:r '; in 0 onden: i> ot.en'c, had mounted in series n,' v'eC the. Line and can be arranged, if it is necessary, on the outside of the telephone device, see: in. 1 'mounting against the wall, here in the form 1' 1;: a device connected by u @ flexible cord and placed on a desk.

   This appliance requires very little maintenance, and this maintenance can be
 EMI12.2
 aure by a staff almost entirely devoid of e 1 o j - iî10tion bzz particular.



  The local exchange is called by unhooking the handset and turning the generator, after which, at the end of the production of the alternating current, the a is caused. x x o c 1; B, t 1 o; .i automatic of a local junction line with searcher and connector with the line through which the call arrives, which the loop of the calling party maintains. Some telephone devices may require a minor modification to their assembly to provide
 EMI12.3
 in an effective manner the f.nct i0i1J1ement which has just been described. The earpiece is then placed against the ear and the signal button is pressed.

   Short tone pulses coming up from the local trunk line
 EMI12.4
 when fjO; Î connection switch o.;:; $ l: 1'e its selection operation is then perceived in the earpiece, and we
 EMI12.5
 1st count until a number has been heard that matches the desired line. We then release the button, and a

  <Desc / Clms Page number 13>

 Ringing tone or busy tone is perceived exactly as in the. normal automatic operation.



   In cases where two digits must be transmitted, on. release the button after counting the number of pulses corresponding to the first digit, then push the button again, to transmit the second digit.

   The pulses are transmitted!:, At a relatively slow rate, so that there is no difficulty in stopping the selector on the desired contact. This process gives complete satisfaction in loops with resistance up to 3000 ohms, and since the usual selection relays A, B and C are not necessary and the electromagnets have ample time to be excited, the system is very robust.



   Turning now to figure 3 which shows the way in which the lines are arranged in a tandem plant like the one denoted by RE in figure 1, the upper part of figure 3 represents a typical equipment of line LE with the local device LL of connection, and the associated common equipment CE. Local calls are routed over the LL link by the subscriber in a normal manner by issuing any of the two-digit numbers from 11 to 60.

   If a 7 is transmitted, the connector side of the link device selects an outgoing trunk line going to the main exchange, in which case the OG relay is actuated to establish line continuity from the local control device. link, and at the same time to cut the inbound route from the junction line to the IS input selector.

   If communication is to be established from one of the remote central stations RA or RD, the TH1 or TH2 uni-selector represented in the tandem repeater TR1 or TR2 returns to its position of idle to find an outgoing line junction with the P.

  <Desc / Clms Page number 14>

 
 EMI14.1
 ëi on 8u21JOB0 alore that a: J, bOMI (: - from the tandem exchange RE ect in tra.in to call a subscriber attached to a remote exchange as RA or: R17, ¯ the call by: se by the intermediary of the oi> é> <i? trice of central P, like that. C1. ^ CE) t: lzf has been described, this operator then inserting her plug d9J1S the output jwe7c to drop the OG relay.

   The input selector 113 undergoes by the oleCtiOr 1 .. m8,; work: which the ffiif 1.'1: 1. :: -. :: 8 "1: 'on the level 9 or 8 which dOf \, i0 access to the trunk line fECG'57.1: 1'Pt and new i (lIJ1Ù $ ion: ;; are tr8YJI: .mi ::: es to reach the delusional subscriber. When we got
 EMI14.2
 the latter, the operator operates a signaling key.
 EMI14.3
 



  The latter 8, the effect of causing the central to dauM. tandem identification of the line of the calling subscriber by means of a marker transmitted through the local connector of the link FS and the finder of line T, 1, and the uni- voter who, d. tt.ix the tandem repeater TRI or TR2, is connected 8, the junction line with the remote exchange proceeds to 'on.10, yo.; 0 of its contacts to find this reference. When 1'8 is reached, the âipo: local jitif of li8L; o, '1 falls, but the operator remains 81XC 18 line through the input selector jU''1U'8 , so that she made sure that the conversation f ,, 'éClle,! "G8 as it c onYieÍt, 1 :: 11e then removes $ and1 record: .. f't causes the fall of the selector due to the junction and from- 't1':.; r., the only equipment still maintained cI:, Y) 1; ' the central EE û'Ga., '1' the repeater in tandem.



  In a similar way, in the cax of a call coming from a distant exchange and destined to c1 a subscriber attached to the exchange in tandem, the tandem repeater formed by a tlr.:i 1gC'te't, x 'sweep sew contacts to find the jonctio line' - '' with the central of the next higher rank and to activate the OG relay,: The o1Jé: catrice pushes in its plug el8 [i the call jack, it drops OG relay and selects the desired subscriber. Then she reverses the. key of si- // 7

  <Desc / Clms Page number 15>

   ion., which has the effect that the tandem repeater searches for the subscriber request, but this time directly from the input selector bank. The input selector drops out after the control maneuver as before.



   During a call going from a remote exchange to another remote exchange which are both connected to the same exchange in tandem, the repetition unit selector of the tandem exchange scans its contacts to find the called trunk line marked on the input selector in a manner similar to subscriber tagging.



   For all calls routed by the operator, provision has been made for the line offer, cut-off and controlled ringing. Scanning according to the P.B, X system. is achievable in the exchange with 42 lines and contacts numbered by two-digit numbers, at the liver by means of a large group P.B.X. obtained by transmission of a one-digit number, and through a small group reached through a two-digit number.

   In all the calls that do not go through the operator, provision has been made for cutting off the communication as soon as one of the correspondents hangs up, given that in the calls that are established without the intervention of supervisory staff there is no point in providing the usual warning device which indicates the maintenance of communication with the requested subscriber.



   It is also possible to provide for the possibility of a control by means of a private wire to allow the operator to select the subscriber's line in order to exercise control over the establishment of the call or assist in establishing communication.



   A test call device can be provided which allows the operator or a verifier at the next higher central station to establish a call.

  <Desc / Clms Page number 16>

 from any exchange in the network back to the next higher-order exchange. This group uses exactly the same hardware as the subscriber and works on
 EMI16.1
 the; lines of the circuit well COj ') f.u of musing in return for. the "doors out of order.



   If we now consider the detail of the operation of the circuits, the values. characteristic ':, constan-
 EMI16.2
 your. of certain windings of the relays and, cry: .. your these will be indicated to serve as a guide in a general way.
 EMI16.3
 the 31st, the supply voltage being assumed equal to 50 volts.



   If we first refer to the subscriber line circuit shown in Figure 4, we see that when the maid picks up her earpiece, to loop her SL line, and
 EMI16.4
 that then he turns the handle of the ge <ié: aatxaice, the relay which comes into action under the effect of alter currents, native e; 1 due to the, capacity L 0, A and the rectifier MRA, is actuated and in turn actuates the relay L but prevents its contacts from exerting an effect.

   When the ringing has ceased, the SL line remains looped and relays it L rete locked via contacts L2 and the conductor
 EMI16.5
 common 11 going to a relay, d.e starting dS connected to 10, battery in the common equipment (figures 5 and 6), this circuit putting the common equipment which causes the scanning by a
 EMI16.6
 di8 line finder: po;

  it if local link for the purpose of searching for a battery marker applied to the bank P in the multiple finder LFlK an moye "'des contactt) L1, When the finder reaches the line, the relay C0 is excited by the intermediary of the P conductor, it disconnects the: C'L-'1: 3.i: j L and establishes the continuity of the line SL to the local connection device.



     During an incoming call, the CO relay is actuated directly via the multiple connector

  <Desc / Clms Page number 17>

 FSM and from the normal conductor P to disconnect the relay RU. The resistance of 500 ohms across the CO terminals is provided to obtain a. fast and efficient operation of the interrupt relay in the local calling device.



   If we. now consider the common equipment of figures 5 and 6, the allocation uni-selector AL (figure 5), which gives access to local link devices whose number reaches up to 8, will normally be stopped on a device free connection room, given that the earth potential which is applied in return from local connection devices which are occupied, by the intermediary of conductors like the conductor 12, causes the in. - automatic dragging of the ALM solenoid of the uniselector via switch ALMC contacts with movement over the occupied outputs,

   each of which is connected to three successive contacts on the switch banks AL. If all the junction lines are busy, the earth potential is removed from the common conductor 13 and thus causes the application, at rest, on the last contact, of the uniselector AL.



   . Operation of the SS relay from a calling line circuit causes the application of a potential of. earth via the bank AL2, in order to return the preselected local connection device to the. calling line. On the SS4 contacts, the SS relay also causes oscillation across the RR timing relay, of the type described in the patent application filed in.

   Great Britain on September 5, 1938, by maneuvering? its unique pair of contacts. This causes the PU relay to be energized which, on the Pu5 contacts, completes a circuit which starts from the earthed conductor 13, for the assignment electromagnet ALM, and, on the PU1 contacts, energizes the RS relay which, on the RSI contacts, locks and cuts the initial circuit of

  <Desc / Clms Page number 18>

 
 EMI18.1
 discharge from relay ER and, on>; contacts R82, gives it an impulse in reverse h'ena to make it oscillate back t, t cut ': 1inl: d. the relay circuit hù '.

   The duration of the pt - '' Y'iodine of oscillation of x'ei.'7i4? 1 had rti.:16e c1.E "so as to be # 0.75 seconds, and at each oscillation a pulse is o.;., j) lic \ ljr2e hay! ' 1 'lect: r0-aim87, t 9 ± l1 <î à.e 1 'nnhlé1ecteUl' and eg, 'j, - the {.1EJ, t at the rhythm relay itself. for mgirtbtain [; iOn 0: ;; 011- la.t¯.ow. ; a, x conquered, less than 1.5 seconds, the effect device, 8, tioJ'1 provokes a reoperation of cardemJit by deletion on the basis of the selected li2aor.

   This te: rn; ar e ", t uuf- fisét) 1t for the researcher 4u the local device of liEÜ" on to perform a complete revolution, and the search operation
 EMI18.2
 it must end within this period, If it does not:

   If not so, it indicates Inexistence 0. 'a bad state of the line, and that it is necessary to automatically start a second link device, which occurs when the
 EMI18.3
 allocation device advances pax to pElé! until the next connection device, if this last one or any of the following ones is occupied, it is quickly exceeded by means of a
 EMI18.4
 advancement pae to is a. automatically interrupted.

   If the result of the search does not appear normally, the potential of 1v earth is applied to the ba, nc A-L1 from the link device, and the device must be advanced. assignment starts the immediately following output.



   The RR rhythm relay also controls, by
 EMI18.5
 via the PU relay. advancement 1) [L in steps of the u.i-fÉ lectetzx 'TP of the impulses ::; of time.! (figure 6). This step-by-step advancement begins when the relay TP is actuated from its starting position via conductor 15 and from the link circuit, and it is
 EMI18.6
 continues by means of contacta PUS and Tt'5.

   When the switch T1 'is in the rest position, the earth potential ikflt applies via the l.ra, la.i TP3 on the

  <Desc / Clms Page number 19>

 conductor 16 giving the impulse "S", and advancing step by step at the rate of one step, in 0.75 seconds, the brush TP4 reaches the contact 49 corresponding to the impulse "Z", which is connected to the conductor 17 corresponding to the "Z" impulse, after 48 steps, that is to say after 36 seconds, On the TP4 contacts, the TP relay also starts the ringing and the tone by energizing the vibrator relay VB of the bell and the LV relay of the. busy tone, while on TP2 contacts it maintains the RR, PU and RS interaction circuit independently of the SS4 contacts.

   



   Vibrator relay VB supplies ringing current to conductor 22 in a known manner causing continuous ringing, while relay BT provides conductor 18 with the tone indicating that "number cannot be obtained". Also, since the TP switch advances one step every time one has elapsed. time of 0.75 seconds, alternating contacts of the TP3 and TP6 banks can be used to interrupt the continuous tone supplied:

  by the LV relay and break it down into. a tone applied and interrupted such as it is used for the indication of the occupation, its application being made on the common conductor 19. The contacts PU4 and the brushes and banks TP2 and TP5 actuate the link IR for two short periods $ equal to approximately 0.3 seconds in each three second cycle, and this relay provides, on the IR1 contacts, a verification tone through the common conductor 24, and, on the con - tacts IR2, and through the common conductor 21, an interrupted ringing current, and also through the capacitor QD and the common conductor 20 an interrupted ringing tone.



   If we. refers now to the local-connection circuit of the terminal exchange 9 + 1 of .figures 7 and 8, when the connection device is occupied by the allocation device.

  <Desc / Clms Page number 20>

 
 EMI20.1
 tatioT 'due to the application of the potential of 18. earth via the conductor 14, relays it. ASS had excited, this relay establishing this .fa, it, on the. contacts AS1, a tewa circuit for the ArH relay, and on the COy.té1.Ctfj ABS2 a circuit 'en.cr9ÍYoemei't for the electromagnet AL]' IIÎ of the search C} c: t: 'r of line, tended that ur lek1 contacted A8133 he operated relay M.

   While operating, the AA relay causes, 8U1 'the AA1 contacts (figure 8) .'o, c.11.¯.i; â.oY of the armature of the ARR rhythm relay which removed it from the key, contacted ARR1, which is a difference from iii reia, 1.i RR of figure 5 which closed its contacta 1o2.a of its excitatio; z, te ".c1h, that on the contacts àà2, the relay AA causes, the recall of relay AE from one of its two positions <1 <: 0 or 12 rest of '0 [1) 10 A.FS4 of the connector switch.



  ] i "function (aY1t, relay AE prepares contacta A: E3 for an operating circuit for the telÉ'.iE>: L .. 'Ü.



  When the finder AL3 "reaches the line by which: e makes the call, which this :( 'e}! (, J.'e by the potential of the battery ixiir the bank ALF5 and by the ütc: xmEdiary of the, e:> i :: t, this YA and the CO relay (figure 4), the AFli relay is activated by the intermediary of its two windings !; ': in saw, at the st :: i.te what it applies [, ml 'le,) contacted AFH2 a potential (the guard and maintaining on the occupied output, while leo contacted AFH1 it causes the maneuver of the x = elai> Air and disconnects the drive circuit of the switch.When operating, the relay AFR causes, on the contacts Afin1 and An3, the establishment of the continuity of the co conductors:; fle;: ±; Jtion jl1 , qn'8, He relays.

   AA, while GLU 'les, contacts AIP2, it disconnects the earth potential of the common conductor 13 of the? 8A "SOi ;; e and also applies the potential of the, earth to the conciuctetzr 12 so as to advance. the assignment switch taken at worst, in the horn equipment, one, on another local device rie free link 7

  <Desc / Clms Page number 21>

 so that the device is ready to receive new local calls, while, on the AFR5 contacts, it completes another holding circuit for the AE relay, that, on the (, AFR7 contacts, it energizes the ATS relay from of the conductor 16 corresponding to the time pulse "S", and that, the contacts AFR8, it disconnects the relay ASS.

   Then, on the ASS3 contacts, the local circuit for maintaining the AA link opens, but this relay then remains maintained via the loop of the calling party. While operating, the ATS relay locks through its upper winding, while on the contacts
ATS2 it applies the potential of the earth to the conductor
15 which ensures the start of the production of the time pulse as well as of the ringing current and of the tone, while on the ATS3 contacts it connects the ATZ relay to the conductor 17 of the "Z" pulse.



   When the subscriber acts on his call button to initiate the selection maneuver, the direct current calling loop operates, and the AA relay drops out, whereupon the ARR relay a. the ability, thanks to AAl contacts, to oscillate in return and thus make its contacts act
AARI on the APU relay.

   While operating, the APU relay causes, on the APUL contacts, the excitation of the AFSM electromagnet of the connector, and, on the APU2 contacts, it causes a slight excitation of the ARR relay to ensure continuation of the oscillating movement, while on contacts APU3 it applies the tone indicating that "the number cannot be obtained" through the intermediary of the common conductor 18 and the AA windings at the station of the calling party, this tone being used for selective transmissions.

   When the ARR rhythm relay opens its contacts, the APU relay drops and de-energizes the electromagnet of the connector, and at the same time opens the tone circuit.

  <Desc / Clms Page number 22>

 
 EMI22.1
 lite, the subscriber having received a tone pulse echoing a step of the corrector. By falling, relays MU <1. <k> energizes the AER relay which does not. this fact oscillates back to close,; E '. \ 5 01-It e2ct ARR1, and the cycle of operation begins again in this way on its own, the calling subscriber received a tone pulse for each par .: of the connector.

   As soon as the connector gave up. 8G. iJ o i; 1 t 1 o r, from 1.> #: Po ::. , the AFS4 brush applies the earth potential via the contacts a AH6 and AB5 for o.8l <: I: 'er the operation of the relay AEg, this rels'i, preparing, on the cont!: Tct:,; AERl, the coiirt-circiiitage of the relay. AE, while ciue J; \). R leo co; ùta, ctv AERS it locks itself and that ur contacted them AI: R6 it prepares a circuit of te; #t for relay AH.



  When we 1 3 c l.i e 1 'button of e x 1 gn T 1 1 s f¯> .t: 1, o r <after we have. received a number of tone pulses which; corresponds to the desired digit, the r61 "Ü :; 1- \ A activates again and, on the (; OO}", t ') ct8 .. ! \ ¯f \ .. l, open any other circuit for 1 ': -. relay APU and stop 3.iN; i the advancement pae not, while, ;;:. <ii :. In contacts M + 2, it short-circuits the AS relay which begins to fall slowly.

   During the. period of fall to ix i., <# î # =>, i AEI a tet circuit:. '' # complete via oe:. ;; cont? ct: ;; AAI, @ lfi6 and AE6 for relā1 <AE by 1.'i <'> tt; iùié <1.i.air of the broom and the As5 bench up to the normal conductor of the subscriber request. tji is a subscriber <:. l free, the relay, excites it in series, with the e;. e 1 1.i demand subscriber cutoff CO and the r <µ .-; i.>: 1? i ;; e Y; E (figure 4), and, de. : 'when relay & Ar, 4 drops, it initiates the operation of the bell of the correl3p 1'î- d'? - t 6.erf1 ': 1 "d, pnr 1.' i:

   t e r <ùé d. i a. i "r of the common conductor 21 and of the AF relay, a feedback circuit being complete]? 8.r the intermediary of the ar é>? iwta:,?. c ÂYB and of the conductor 30 to the battery , while on the contacts A-H2 18. tone ôe

  <Desc / Clms Page number 23>

 ringing which comes from the common conductor 20 is supplied to the calling party.



   When the called party answers, the relay
AF functions to cut off the ringer and to establish the continuity of the conversation conductors, after which the AD relay comes into action through the loop of the called party and in series with an APC differential relay which, in this state of operation, has no action. While operating, relay AD. Covers, on contacts AD2 and AD3, the time pulse circuit for relay ATS, and, on contacts AD1, opens the circuit for relay AER which, by regaining its. previous position after the end of its delay period, causes, on the AER4 contacts, the opening of the circuit. tone of sound-. born:

  from, and on the AER5 contacts, the application of the earth potential, for metering, from the brush and the bench
AFS4 and via contacts AH6 on the M conductor of the calling party's line circuit. It can be seen that the contacts and 19 which correspond to the number 7 which is used to give access to the s @ rtante junction line with the main exchange are not connected to the metering circuit, therefore in the case of calls passing through the Through the operator of the main exchange, no recording is made in the counter of the calling party.



   When operating, the AH relay also completes a communication circuit between the ALF3 bank of the line finder and the corresponding AFS3 bank of the connector. The functions provided by both this circuit and the APC relay will be described further in connection with the calls made by the attendant to the input selector in the figures.
9 and 10.



   If the called party is busy when the

  <Desc / Clms Page number 24>

 
 EMI24.1
 corrector l: i''el'1'ete ur 80 lit;, le, relay AH .Se can operate during 1> er.io <; e drop of relay AE, consequently when relay 1 drops, the busy tone e, returned to the calling party via conductor 19 and 'v to. vs.

   COf! Ti.Ct; ¯: Ali2, AER4 and lÚ "2. If we consider E; üis¯1. L.rV E. i1 .J '!' le, -, different condi- tions 1 ;; Y-> #;,; o:;. y; $ L'S 11 i this cut of ti. ii, at> o ;; 1 .t 1: locol of e 1 . 5. w. I +; o: rL, we see that Mi le cor: ce '; i! O)' id'3.nt calling party hangs up $ 9.; - '.: ;; maneuver the igno button .lh, 1tio (I, this equals 8, the 111a- T. work of this' button, 1111 j, fi9 i'i 0 l Qat? to r.'0 '' '.:!'! CO n, D3.r1. These C0 '! C: J.4iOry', the connector continues to advance}) a "step by step. which it arrives at its next rest position, which E;: .. t for example position 12 in this case, 8, following which it '?' establishes a circuit which "hnnte the relay AFH by j. ' i, r '! tQ, rï (If: C! .à, i.àr2 of the broom and the AFS4 bench and of (, contact J \ .LP.} 2, AEl and A} j'R4.

   On falling, the AFE relay drops the AB% 1 relay which, in 0.1 turn, destroys the LIE and AER relays, and all the relays are then in their normal position.



  In the normal8 fall conditions, when the clem correspondent: 3ndeur hangs up, the liE relay is already in bf1 pof.; I.cio, -, Toor.'1î181e, so that by dropping the relay 'AA causes the fall. of relay8 AIPH due to the short-circuiting via contacts AA1,, H3 and to + IE4. When falling, the relo, i1 $ ÂFH causes the relay to fall. A-FR which then drops the AH, AF and AD relays. ±, or * from the drop of relay AD, it sets up an automatically interrupted circuit for the electro-; Jirùant AFSH by means of the AF.S4 brush, and the connector advances to ti..l .: 'lk :, its next normal position.

   In the caB where it is the correspondent of- <> ipni 1 17.i hangs up the J: CeriliE: r, by dropping the relay AD causes hUT the; :: contacts 1 \ .. D :: 'the application in return of an earth potential key short-cirouitage through

  <Desc / Clms Page number 25>

 contacts AFR5, AD1, AER3, AF1 and AFR4 on the AFH relay, which leads to results similar to those obtained when it is the calling party who hangs up. '
Under the falling conditions obtained by means of the time pulses, if the calling subscriber has omitted to transmit his signal at the desired moment, the pulse Z is received via the conductor 17, or else.

   if the requested subscriber has not replied within this time, the ATZ relay, when operating, drops the AFH relay on the ATZ1 contacts, and the other relays then drop in their turn.



   The local exchange input selector circuit, which is shown in Figures 9 and 10, is used for all calls!:, Other than local calls.



   When a call arrives from the main exchange, the loop established forward by the operator through the junction conductors 40 and 41, either directly or through the intermediary of the operator. 'an intermediate exchange in tandem, causes the operation of the relay BA in series with the differential relay BPC which, at this moment, exerts no action.

   This operation is followed by the energization of the BB relay (figure 9), the BG relay (figure 10), the BC and BE relays (figure 9), and the BOVER relay (figure 10) one after the other, which has the effect that the access from the circuit of the local connecting device (shown schematically in the lower left corner of FIG. 9) is occupied on the contacts BG3 by the disconnection. of the battery potential identifying the occupied circuits, this operation being done by means of the LP relay winding at.

   parallel with the BYG resistor, while the pulse circuit is prepared on the contacts BE4 and BG5 through the low resistance lower winding of the relay BC, up to the BSM electromagnet of the selector.



   When the attendant selects a corresponding contact

  <Desc / Clms Page number 26>

 
 EMI26.1
 laying 0U ihïü (-l'0 0 dl 1. C o :( "('e" .LJOJi r. "' J) Y raved d, a; ai. the hundred 'L" 1 lt ei., iiî: 1 .>>.: 1, the BA relay repeats e µ5 oi: the Qcio) 1 of the train <1. 'in - 1) \ Ü, -. ior ,,. the & imf, \ Ù, .. io) '11> for .1 'c': lf: ctro "8ifl13Ytt i B If, 1 of the selector, 8. follows (;; of what let, bol1ib of the switch;., ont '= "T'1i, cé: o, paM al} f1S along se :; la ^, V'GS d' \ :; ('13: ī'50Yn c01': re>. .poy- tî-a, "'0. eï1 (' y? ï '(t sending the pulse trsi: n.! ;;, relay BB ee nï'-i: ini; iC':" 'G pctiowe par>; à5.te de bO / 1: C'f; tf: 1: cd, and the oe'ela, i> 5 BC me 1U8 keeps actuated because f30n upper winding ei> .1 is short-circuited }) 9.r the intermediary (1ef; contacta BG4 and BCI \ fl1, de l, (;. ') "" (' 0 \ Ü6mu - .. t higher BC and det 'contact:;:

   BE3 and B81J: C connected to 18 earth through the 'bench and the
 EMI26.2
 broom BS5.
 EMI26.3
 



  At the fiY \ du tr.J.i: <., oh. 'i; .ùà> i: 1; # <S.ai <; # le & rela, i ;; BA and BB xe; -, teïct mo, L1te: '1,). S, and the yelaih BC falls slowly. When the relay BC drops, a test circuit is established for the $ two windings of the Bit relays in series by means of the brush BS3 to the normal conductor P of the called line, while e. n the same time :, the cixctziÛ of the relay BE opens and this relay begins to fall slowly
 EMI26.4
 is lying .
 EMI26.5
 



  If the. requested line is free, the relay BE between the action and establishes, eu "c lex contacteda BH1 and BH2, the continuity of the junction-incoming league until 3ur 18 line of the:, b 0'0 (1 é c1.erJJ-andé, f; J1.ï'f. 'Que l': f: H!; 1 ': 3: t.rice receives da' "''. 'This tone caa . The attendant can o.lo: r ring the corres- yōt (3a t requested by applying an imbalance signal of
 EMI26.6
 battery via the junction line, this si-
 EMI26.7
 gnal comprising ¯Application 0.1; battery potential & ur both wire.;, ie conversation.

   Ut: 6 the effect of this) j9, - work, the celais BA rex. Maintained, and the 1'61ai8 BJ? C is activated and suppresses, Mur contacted them BPC1, the short-circuit of the relay $ Blic which works in series with the battery of rxilj.s2, tioxt. biur the contact8 BNC1, the relaio BlC em-oê-. r

  <Desc / Clms Page number 27>

 when the BOVR relay drops as a result of the opening of the BPC2 contacts, while on the BNC2 contacts it activates the BRR relay, following which, on the BRRl and Brr2 contacta, a permanent ringing signal is applied by the 'via the common conductor 22 on the called line.



  After a short application of the ringing current, the unbalance signal is withdrawn and therefore, when the boo @@ é desires to pick up its earpiece, it can enter into convocation. with the attendant via the input selector circuit which remains safe from occupation from the local link device as long as the attendant maintains communication. When the called party answers, the relay BD comes into action and reverses, on their contacts in BD1 and BD2, the potential of the battery applied to the junction line, so as to provide a check indication. the operator.



   If the desired correspondent is busy, the BH relay cannot come into action during the fall of the BE relay, therefore when the latter falls and because of its fall it activates the BC relay again, removing the short-circuit from its upper winding, the application tone is applied through the intermediary of the common conductor 19 and the windings of the relay BA to the operator.



   The attendant can then offer the call to the busy correspondent, by applying a signal obtained by the imbalance of the battery, which activates the BPC relay which in turn ensures the operation of the BNC relay as before. This time, as the BH relay is in its, position. normal and that the relay BC is activated, while operating the relay BNC applies, through the contacts BNC2, the potential of the. earth via contacts BH2 and BC5 to operate the BCN relay.

   This: BCNx relay / locks via its lower winding on the

  <Desc / Clms Page number 28>

 
 EMI28.1
 contacted BCT2, while M2z contacted BCN4, it maintains relay BC as long as the imbalance signal remains applied. our 1e; 1>: 1 cO! 1t'J.ct8 BONUS and BCH3) il 0,1): '; 1 <1'6 the connection of the junction line via ne: capacitors Boa and BOB up to 8Ul 'the requested line.



  The operator then nun avic, corresponding area which '., Oï't en CO {)' \ Te1'8é1t: tO: n to have li hang up, and she removes the:, i # ria, l of imbalance from the . j unction line, at the. following which the BPC relays and: SNC revie, v'0, 'it d.:)i1fl their previous position, t0.ndi:,; that the BC relay also comes back in the previous 08 2oition while the calf! :-) GOOD rete maintained.

   A new application from: igr: a7. of imbalance pro VO (11th J 1 ox, the ÓtaIJl: L8 ,,, ement of a cut-off circuit, being, 1 on ;; that the BNC relay applies 9.10:!. '",; e entering in action at, nsiweam, and 81). :); ' contacted them BÚC2, the full potential of the earth through the broom and the bench Bs3, in order to; 11Hlyt E: 1. " and put 110; service t 0 l le; #: relay of C] 1 "- :( '0} 10U1'13 or COi''CE: IZJ'rj de, Ei: -: j> O:, local iVl.5 of 110, il-; we already. connect & to the normal conductor i of the 'bo''1, .é request1. (, When the imbalance is removed, it relays: BH comes into action via ", e, :; windings in series of 18. eh J 'n 1 .tīie 1 1 e, and a new application of': 1lG''l ::>. li to. side.,.; C; Cjizil ; .bY'e causes the 1.ù EEIA relay maneuver; for the ', 111- plicption 01 (; 0 iC "t c1.B e;.;

   o> fi> n e r 1 and), the subscriber requests, 6th the 'same; <: -, g; where; n that;, the subscriber was initially unoccupied.



  When the c 0: 1. - (' <;) ;;. '. 0011 (1 ..,.,.' T. Request hung up, the re- 1! Is, BD drops out, and by reversing the ran through the 1, y; "(lE: junction so ii return do 1.1:; y, '', 'I; n, t j. 0' 1 '0 -'; 'I11: o.Ü0 this relay gives operator U) 1 release siVyWl.1 When it withdraws the plug, relay 31i, 83, BOVR, bzz, EH st BC or i Bc ôi in turn drop, and the switch BN returns to 8 r0ob position.



  1. .rt the case of an outgoing call, .LOZv3qli'lîl subscriber 7

  <Desc / Clms Page number 29>

 local dials the number 7 corresponding to the outgoing junction circuit with the main central, the AH relay (figure 8) of the circuit of the local connection device is connected to the LP relay in parallel with the BYG resistor. In fone-
 EMI29.1
 When operating, the LP relay causes the operation of the BOG and BRF relays, the latter being slow to operate due to the BYJ lo xé3.tance in series and the BQ, C capacitor in bypass.



  During its period of excitation a musing pulse is sent to the front from the conductor 22 and through the junction conductors 40 and 41, to occupy the equipment at the end of the junction line
 EMI29.2
 located on the side of the main exchange, because the contact BOO2 and BOG4 are activated. The ringing pulse is repeated in all the central tandem exchanges.:, If it is
 EMI29.3
 necessary, so that it will be described in detail further.



  The ringing from the local link di $}? 00HH will be interrupted by the. BYP resistor which is connected to the negative conversation conductor until the BRF relay comes into action.,
When the operator introduces the ... plug into the jack which corresponds to the junction line through which the call arrives, she checks both the correspondent's number
 EMI29.4
 requested is that of the applicant, as a verification. (.



   To check, the attendant selects the requested number in the reverse order as well as that. will be described later, and when the junction line 40, 41 with the terminal exchange is occupied, an imbalance occurs.
 EMI29.5
 tane of the battery. is applied in return through this trunk line on the local connection device providing the call, for m0) '160uv: r.e:

  r. relays it AfO (figure 8). This then has the effect of applying the battery voltage in the forward direction via the @
 EMI29.6
 resistance Atd, contacts APOl and AI-14, brush and /
 EMI29.7
 bo.n.c AFS3 and driver D: for;, xovuct: ex la lI19floeuv "J.p

  <Desc / Clms Page number 30>

 
 EMI30.1
 of the relay 'BOG (figure 10).

   When operating, the BOV relay causes the Bovy relay to Maneuver & ur the & conta.cts BOV1, la! '; 1> it (': of what, on the c 0 y: B 0'-T # 5, a circuit 10 - The maneuvering cal is completed for the BA relay by the intermediary of the BYD feedback, after which the 3: 8 vêlais works. 'The contacta BOV! -t2, the' celai !; 'BOVE col- pied. 1t> <5g.ù.i <gùi.e: ht a worm circuit: <.Di> ii.1.ià6; for li> s¯-vié <>: e and opens the initial function circuit. '' 'emcnt for the relay BOY, mli :: this relay remains maintained by means of the cc> it; <.cti E0Y5 ju:;, qt:. 'so that the from to.é, seqi ilibr-e is z, e 1 ii: r. é.

   Q, ua, ", (1 <? 1 e g; i ii? .? ends, the AFC relay (figure 8) 'tom1), 0t must fall in My turn ¯le a-eli.ioei BOY and 1'91' cone- cies 1'.e18, h: BOG, Di returning from ' jna & a normal position, the BOOG relay activates, on the controls: ntr, ct <; BQG3, relays it BG, la. following which the & relays 130 and Bye also enter + .ctior>, and that contacts BOG2 and: BOG4, the BOG relay again connects the junction line to the BA relay which>: ii.s, n ± <%; GJ1 h is maintained by the iflteoe, 1. <iéôia: ir <# of this line, at the same time as the'contacts BC2 have 6.éb, #. a;? ched the circuit locxi (i this i ';> 1: Jà, i, 1 ire. of the. BYD resistor.



  1. falling, the i: ei.aix BOY a prolongs i?; N local holding circuit., Po.r #. 1 '1. <., t e?., ùié to. i a 1 1. de la;> r- é s 1 n t a; =, c BYE and des. contact B133, and for the local connection device through which the call is made, up to the called side of this circuit.



  The operator selects o.lor -! .. the reite of the n.umcro, comprising the single digit 0, thc: i; a.ii, t; for z, s> iirer, the 1; 1 == 1ne?; i = :; i <=,> =. t 1 ob dane the terminal centT'pl, and the voter BS (figure 9) is linked in conquence) 1 <: relay BC 1., e iiia 1 ;; t 1.> = = i ..., in the usual way, during transmission <; tr'ji.n <.. i -;,; :> i =. i o: n i; , We see that, as long as the Br e <# .l;> e, t S. c <;,; .fl; 1, the normal te & t circuit of the relay.

   BH e is ù.:, I # àof;> i: r. the.':. cIn.t:? ct #> BQ6 and that eo, place we prepared a circuit for the: 1.'810.1: ;; BVR j until i; i: - ie 'oi, iaii BE4 * At the end 5-1'

  <Desc / Clms Page number 31>

 of the pulse train, the relay BC initiates by falling the slow drop of the relay BE, and during this time the voltage of the. 'battery is applied in return, through the resistance BYH (figure 10) and the contacts BE6 and BC3, of the' wire D as well as of the local connection device by which the call arrives' and represented in figures 7 and 8, On wire D of the calling party's line circuit.



  From this point, this voltage propagates to the BS4 bank of the input selector, the wiring of this switch being multiple between this selector and the local connectors.



  Consequently, if the number given by the calling party is indeed its own number, the ISR relay comes into action under the effect of the potential of the battery applied to wire D, and, by operating in this way, it sends back to the BVR1 contacts, the verification tone returned to the attendant via the common conductor 24. The BVR relay is also locked via its lower winding which is dependent on the BCN relay.

   If the requesting subscriber has. given a wrong number, one does not meet the potential of the. battery, and the BVR relay is not energized, so that when the BE relay drops, the attendant receives the busy tone via the common conductor 19, which. tells him that the number given as that of the calling party is not correct.



   The cut-off signal for verification consists in applying the earth potential to the two wires $ of the junction line. Under these conditions, the BPC relay goes into. action, but not the BNC relay, since now this last relay is in the short-circuited conductor.



  Consequently, the holding circuit of the relay BOVR is cut on the contacts BPC2, which causes it to fall under the effect of this operation. When we remove the imbalance,

  <Desc / Clms Page number 32>

 the BOG relay:, 'energizes again via the
 EMI32.1
 contact! .. BPC 2, BOVH2 and BPZ, and ur! & '. contacts BOG2 and BOG4 it causes the 'reconnection of the
 EMI32.2
 junction with the demO subscriber, ndeu: :( 'by the initial route 1: .. i :: 1, a: <> t through the loco.1 linkage device in figures 7 and 6. The fact that the BOG relay enters <:; i :. action again also causes the fall of the valais BG and BC, the switch Bci returning to its previous position.

   1 <1: lajov BA and BB return tiac.1 to their previous position when the: ce- 1;: 1 BOG enters. action, ü117., i> 1 e #,: 1, e 1 # <. i. Bp, BEF and bon: 1: '6Htent eJzc5, "oé;:; throughout the. Converllation which then takes place, and they. Return to their initial position only 1ol: clue the local linkage dipo & itive is released by the fact that the calling party hangs up.



   With regard to the possibility of private control of the. connection through which an attendant can select
 EMI32.3
 operate a subscriber line to control or monitor its maneuvers or to help it set up a call, so as to ensure that the subscriber is able to correctly perform the simple signaling maneuvers required when establishing a call, the operator
 EMI32.4
 $ 0 puts in c01mnUi1ic [, tiol'1 with the subscriber by selecting his number in the usual way through the intermedia.ire of an input selector,

     and after instructing him how to proceed she invites him to hang up and make a call. In. the same time she applies on the. incoming junction line a signal constituted by the earth potential
 EMI32.5
 dcocquilibrp which causes the operation of the BPC relay (figure 10). This releitt, in turn, drops the :( 'el [1.i ", BOVE, after which, on the contacts BOVRl (figure 9), this last relay releases the circuit of the. subscriber by disconnecting the cut-off relay BH from the normal driver P.

   At this time, the attendant applies through the /

  <Desc / Clms Page number 33>

 junction line a signal constituted by the unbalanced voltage of the. battery, this signal causing the operation of the relays BPC and BNC, as a result of which it is now the relay BCN which is activated, because, this time, the relay BC is activated. The BCN relay drops the BC relay at the end of the signal and connects the attendant to the subscriber's line through the BQA and BQB capabilities, so that the attendant can listen to the tones that the calling party receives. of the local connecting device when it starts the call, and it can tell the subscriber if he is making mistakes.



   As all the rural exchanges in the network operate slowly without any personnel, it is all the more desirable that the operator or a mechanic of the main exchange be able to verify that the subscribers of all the exchanges can have access to the telephone. main central. To this end, a group of mechanisms for test calls is provided in each rural exchange, this group being accessible only through the input selector banks, the connection to these banks being made under the effect of the selection, by the operator or mechanic, of the number 7 normally used by the subscriber to communicate with the main exchange.

   This group for test calls works on the lines of the well-known circuit known as "sending a ringing call back in the event of a fault", this circuit being however modified to meet the conditions. that the kind of circuit envisaged in the present application must achieve. Potzx the operator or the mechanic, the process consists in selecting the number 7 in the desired rural exchange and to have access in this way to the group of test calls of this exchange. This has. then the effect of cutting the input connection, and this group is arranged so as to then automatically simulate the issuance of a call

  <Desc / Clms Page number 34>

 level 7, so as to obtain communication with the main exchange.

   When the main exchange answers, an appropriate tone is heard which indicates that the selection equipment of the considered rural exchange is functioning correctly, and when, then, the main exchange hangs up, all
 EMI34.1
 The equipment falls.
The 42 @ 7-link circuit of Figures 11 and 12 which will now be described generally corresponds to the
 EMI34.2
 circuit has 9 -r 1 connections d figure8 7 and 8 which has been described above de8'us.

   The maximum number of lines available, including the !: ', trunk lines, is 49, and this number can be divided, for example, into 42 subscriber lines and 7 trunk lines with the main exchange, or, alternatively, we can
 EMI34.3
 provide a lesser number of lines of 8, bo! 1jé) É; f> and a greater number of junction lines, or conversely a greater number of subscriber lines and fewer junction lines.



   The ordinary subscriber lines are assigned two-digit numbers, from the 11 to 60 series, so that it will be necessary, to establish a local call, to press two
 EMI34.4
 foh1 the button of çigYl3.li # ti0: 't, LOl'fJqu'1:' :, 1 certain number her subscriber lines form a group .L 'W, i. , dv.r "1.s the C3.e. of small groups a two-digit number is selected to gain access to the first line of the group, after which the automatic group scan takes place. DO, 1 ') $ lp case of; 1'8,' 1d group .e..i ,, a number consisting of a single digit can be O'U: ie, t.? T, and there are is the same for the group of lines this junction.



  The 49 dià.pi .ni bies lines are distributed according to the table reproduced above; réu, but OT, realizes that the discrimination banks Cà '± 4 and C} i'S9 of the final CFS selector can be plugged in a different way to meet the. particular configuration desired.

  <Desc / Clms Page number 35>

 
 EMI35.1
 
 <tb>



  Positions
 <tb>
 <tb> Numbers <SEP> affected
 <tb>
 <tb> Type <SEP> of <SEP> lines <SEP> to <SEP> on <SEP> the <SEP>
 <tb>
 <tb> transmit <SEP> benches <SEP> of
 <tb> selector
 <tb>
 <tb> final ,.
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>



  Seven <SEP> lines Ordinary <SEP> <SEP> he <SEP> - <SEP> 17 <SEP> 3 <SEP> - <SEP> 9
 <tb>
 <tb>
 <tb>
 <tb> Four <SEP> lines Ordinary <SEP> <SEP> 21 <SEP> - <SEP> 24 <SEP> 10 <SEP> - <SEP> 13
 <tb>
 <tb>
 <tb>
 <tb> Small <SEP> group <SEP> P.B.X. <SEP> (Three <SEP> lines <SEP>) <SEP> 25 <SEP> - <SEP> 27 <SEP> 14 <SEP> - <SEP> 16
 <tb>
 <tb>
 <tb>
 <tb> Seven <SEP> lines Ordinary <SEP> <SEP> 31 <SEP> - <SEP> 37 <SEP> 17 <SEP> - <SEP> 23
 <tb>
 <tb>
 <tb>
 <tb> Seven <SEP> lines Ordinary <SEP> <SEP> 51 <SEP> - <SEP> 57 <SEP> 31 <SEP> - <SEP> 37
 <tb>
 <tb>
 <tb>
 <tb> Large <SEP> group <SEP> P.B.X. <SEP> (seven <SEP> lines) <SEP> 4 <SEP> 24 <SEP> - <SEP> 30
 <tb>
 <tb>
 <tb>
 <tb> Group <SEP> of <SEP> lines <SEP> of <SEP> junction <SEP> 7 <SEP> 45-50;

    <SEP> 1
 <tb>
 <tb> (seven <SEP> line, $)
 <tb>
 
It can be seen from this table that 42 subscribers are normally arranged in six groups of seven subscribers, with the "7" as the first number to be used to call the operator.



  Therefore, a calling subscriber never has to count further than 7 at any time, and the grand total is 13.



   It can also be seen that there are two main types of groups available under the control of the first digit selected, namely those through which the final link selector advances step by step under the command: from the second digit contained in the number of the subscriber, i.e. ordinary subscriber lines, small group PB, X, being a special example in which the second digit of the number is used to move / the final selector to a position from of which one can be accomplished.

   automatic ba.layege, and those through which the switch performs an automatic test after the movement carried out under the effect of the selection of the first digit of the number, that is to say the group of lines connection and the large PBX group The contact of the FS4 bench or

  <Desc / Clms Page number 36>

 FS9 which precedes the group of the preceding type is connected to terminal S, and the one preceding the latter is connected to terminal
 EMI36.1
 J.

   All the other contacts encountered during the emission of the pulses corresponding to the first digit complete an automatic control circuit of the final selector via the terminals SG and P.B.X., so that
 EMI36.2
 the final selector this transports el '1, .1.', -, group to the other under the control of the subscriber and stops sui? the, the liune which precedes the. first line of the desired group.



   As for, now, the operation
 EMI36.3
 detailed circuit, it can be seen that when the link device is occupied by the allocation device, due to the application, of the potential of the earth through the intermediary of the conductor 14, the relay CSS (figure 11) is energized , which has the effect that this relay constitutes a test circuit
 EMI36.4
 for the CFH relay and the control circuit for the researcher's electro- 'J im9J'it CLEU, while he QIb1, .n; e also the operation of the CA and CFD relays.

   When operating, the AC relay causes the CRR rhythm relay to oscillate so
 EMI36.5
 move its armature away from its cok2ta, ete, while, in functionno, i1.t, the CFD relay connects the CTS relay to conductor 16 of the s ixiiJ i; is> 1 on "S" of tempe, When the CLF searcher reaches the calling line,
 EMI36.6
 the CFH relay is energized by means of its two eY1 bearings in series and then provides, iar the contacts Cvh2, an earth potential serving as a guard for the device at low r, é> 1 & ti, oce, while on the1 ;. CFH1 contacts, it operates the CFR relay and opens the solenoid control circuit. When operating, the CFR relay
 EMI36.7
 establishes CO '?. 4:

  .hitÉ deu conversation conductors until reloi8 ÇA, at the same time> that it disconnects the potential 1. the earth of the common conductor of p8.8B'i ;; e 13 and applies this potential to the conductor 12 of way to advance

  <Desc / Clms Page number 37>

 step by step from the allocation switch contained in the common equipment to another free local connection device. It also drops the CSS relay, and completes a holding circuit for the CFD relay through the CFD6, CER6, CD1 and CFR6 contacts and earth.



   When the subscriber operates his signaling button to initiate the selection of a first digit, the AC relay drops out, following which the CRR relay can oscillate back and operate its @ CRRL contacts and actuate from this. way the relay 0, PU. While operating, this CPU relay causes, on the CRUS contacts (figure 12), the excitation of the CFSM electromagnet of the connector, while on the CPU4 contacts it causes a weak excitation of the CRR relay, in order to maintain its oscillation movement, and that on the contacts CPU1, it retransmits back to the requesting party, via the common conductor 18 and the windings of the relay CA,

   the signal indicating that the number requested by it cannot be obtained. When the CRR relay opens its contacts, the CPU relay drops and causes the connector solenoid to decox and at the same time open the tone circuit. By falling, it also causes de-energization of the CRR relay which, as a result, oscillates back to close its contacts, then the cycle of maneuvers begins again on its own, the requesting subscriber receiving a tone pulse each time the relay is operated. CPU.



   We will first of all assume that we want to have access to the line whose number is 11. In this case, when the CFSM electromagnet is the first to energize and the calling party hears the first impulse dial tone, it returns its button to its normal position to activate the AC relay again. When the CPU relay drops, when the CFSM solenoid falls, their ba-

  <Desc / Clms Page number 38>

 
 EMI38.1
 1 -¯ ^ ï: a in the;, 70:, 7.VOï1 2, following which the potential of the earth N'vpplinue via the 'broom and the bank Clh; 1, the contact S and ràes contacts CI.155, CJ) 'D3, C'1 ..' u and Ci '- / 2 to cause the operation of the CE relay in series with li r,?; .. j.:;,t'1. I 1ce CYG. Ln. working, relays it CE:; 113 locks via its 00-'1 ', ^. Gt 01.

   None: .J.1.:. T: re maneuver, 'the x produces before subscriber 2 derl1o:, Î (tenr presses the button again or': the i> j.Ç.i 7.11: ;. '' 'V1.0? Î for: WL: i .. "C :: 00ti11Je-r the xe..i: C., at 10. :: iiite of what,, H' the 'co' tn , c ;; CAI, ce i? e- If'i ::, make t0lûE, 'the CRO relay and act: Î.o;' "lj16 the CPU relay and that the step-by-step forward maneuver begins again.



  When the broom C? -I4 * .- dyes the poii.tiJ.r- 2 which cr <.z ei; ,,> o:, - Ld at the first row of the group, the potential of t (;, r: l.'e is applied via E! the terminal SG and oonticts Cb5 for ensure the operation of the CER relay which, on the CER3 contacts, prepares the current circuit for the CE relay, while on the OER6 contacts it disconnects the CFD relaigi and completes a local locking circuit
 EMI38.2
 for himself.
 EMI38.3
 



  Since it 1 has 7T.l8, iJ2t8à11t reaches the desired line, subscribes it to the signaling button, operating by this means again: the relay s C Fk, which, on the CAl contacts, stops the movement of advancement step to in. and complete
 EMI38.4
 a test circuit for the CH relay, while on the
 EMI38.5
 contacts CA2, relay Cli is short-circuited via contacts CHS4 and CERS.



  If the desired line is free, the CH relay func- tio ') \ e during the fall period of the> CE relay and, when it.;,' Is discarded by the fall, the ringing (lu cor " C'6sj; londo.nt
 EMI38.6
 requested sounds in the usual way via
 EMI38.7
 of the winding of the relay CF, the ringing tone being returned to the calling party through the intermediary of the conductor 20 and the contacts CH2 (FIG. 11). Yes
 EMI38.8
 /

  <Desc / Clms Page number 39>

 the desired line is busy, the CH relay cannot operate, and the busy tone is sent back to the calling party via the common conductor. 19,
The same remarks apply to established calls, with lines 12 to 17.



   If we now assume that it is line 21 that we want to reach, we release the signaling button when we have received the second tone pulse, that is to say when the selector. ends ,! is changing from position 2 to position 3. Therefore, when it reaches position 3, the interaction circuit between the CPU relay and the CFSM solenoid is cut on the CAl contacts. , but an automatic advancement circuit is then established for the CFSM solenoid via the SG terminal and the contacts CE5, CPU5, OH6 and CFSMC, so that the brushes advance rapidly to position 9 where the automatic advancement circuit opens.

   It will be noted that in this position a communication with terminal S is established and that this position immediately precedes the second group of ordinary subscriber lines, that is to say the group of lines 21 to 24. When 'the signal button is pressed again, the step-by-step forward maneuver begins again, and that of the lines 21 to 24 which is desired is the subject of a selection in the manner already described.



   If you want to get the small group P.B.X. from lines 25 to 27, the signal button is released for the second time after receiving five tone pulses, so that the final selector brushes stop in position 14 'in which the CFS4 brush liaises with the PBX terminal As the CE relay is then actuated, a circuit is established for the CHS relay which, while operating, maintains, on the contacts CHS1 and CHS3, the

  <Desc / Clms Page number 40>

 interaction circuit between the CPU and CRR relays despite the
 EMI40.1
 operation of relay ÇA again, so that the CFS switch continues to advance automatically step by step.

   However, no further tone pulses are returned to the calling party as a result of disconnection of the tone circuit on contacts CHS2, and the CES relay is also locked via the contacts.
 EMI40.2
 contacted CtïS4, CAS, CEl and Ci'T''t6 and the. Earth.

   During the ma- 'OCtxV1 ^ <; of scanning of di.31JoJdt if i '.. ¯'., leu relays CA, CE and CER all of which are actuated and thus establish a test circuit for relay CH, so that if among the lines there are any which are free, the CH relay comes into action and opens the drive circuit on the CH8 contacts, and,
 EMI40.3
 on contacts C} I5, it turns off the CE relay which begins to drop slowly. When relay Ce drops, contacts CE7 (figure 12) and CE6 (figure 11) ensure the
 EMI40.4
 connection of the usual circuits of:, pi7r1e5? iE? and a tone of 801 "Y \ e: \: '1e.

   If all the lines of group "O;" lt are occupied, when the last line is reached, the potential (1.a 1y =. Earth is applied via the CFS4 brush and terminal S (being given that there is always;

  . a P.B.X. with two-digit numbers at the end of a main group) to short-circuit the CE relay. In. falling, the relay CE opens on the contacts CEl the maintenance circuit of the relay CHS and the latter then causes by its fall the stopping of the movement of the switch on the contacts CHSl, while on the contacts CHS2 it provides the tone of 'occupancy to the calling subscriber, via the driver
 EMI40.5
 C Oirlrilt, aY1 19.



  If the individual line 26 or 27 of the group i '.. 1. Is selected, the maneuvers x'acco1là> 1i <r, we ;;. t as if these lines were ordinary lines, so that d'Dn does not cause any scanning maneuvers in the P.B.X system.

  <Desc / Clms Page number 41>

 



     Regarding the selection of any one of the ordinary lines 31 to 37, 51 to 57 or 61 to 67, the operations are similar to those which occur in the selection of ordinary lines 21 to 24, the selector finally passing from one group to another under the control of the subscriber. Thus, under the action of the first number 3, the brushes of the switch are placed in position 16, while under the action of the first number 5, they pass in position 30 and that under the action of the first digit 6 they are placed in position 37, Regarding the selection of digits 5 and 6 as the first digit, it can be noted that after receiving the fourth tone pulse,

     that is to say when the final selector automatically advances beyond contacts 17 and reaches contact 23, the earth potential is applied via the CFS4 brush and terminal J to operate the CHS relay. However, the CHS relay does not lock in this case since the signaling button has not been released to activate the AC relay again, but on the CHS2 contacts (figure 11) it disconnects the circuit. tone. The final selector will stop at position 23 until the CPU relay energizes again in the usual way to initiate energization of the CFSM electromagnet.

   When this maneuver is completed, the CPU3 contacts open the CHS relay circuit which completes the tone circuit and thus allows the fifth tone pulse to be sent to the calling party, while the electromagnet CFSM is excited again. When the CPU relay drops, the brushes of the switch are advanced to position 24, after which an advance maneuver is performed again with automatic interruption to move them forward to the position. position 30 in which they remain if the button has not been released

  <Desc / Clms Page number 42>

 
 EMI42.1
 after the transmission, of the fifth pulse of tono, lii, é ..



  As a variant, they are made to advance step by step into the. position 31 and then automatically up to position 37 @ if the push-button is not released until the sixth tone pulse has been received.



   Regarding now the selection of the large group P.B.X. to which is assigned the number 4 to a single digit, we see that when lek. 'sweeps of the final selector reach position 23 which is connected to terminal J, the relay CA is actuated again under the effect of the return of the signaling or selection button to its initial position, and consequently, when actuating the CES relay via terminal J, the aforementioned relay causes the operation of the CE relay, the two relays are then locked via the CEl contacts,

   and the ma-
 EMI42.2
 advancement work pa;:! at step of the switch starts again.



  Scanning for a free line in the P.B.X group. then occurs in the same way as for
 EMI42.3
 the small group â ',. X, already described, the & sweeps from the interrupt e; ir, when, le0 advances step to l) ::> ,; ' up to 1>: fl th - st line of the group, completed in the usual way
 EMI42.4
 for relay C1R a circuit which to> ass, e via terminal BG. if- all the .. '1 lines of the rump, have occupied, the movement of the switch stops when it has reached 1s last line (position 30), due to C01.1: ct-circl: dtg, Ge from relay CL via terminal S, and relay CEe:

   drops to return the busy tone to the cor- '. (' e:, 'y, 0i10.?,: lt calling party, D3)', 3 the case of the group of ',,! junction lines where the number 7 is ¯1f feGS.té, when the final selector reaches position 44, relays CES and CL -jO), t ¯t.Ct.Oi'1'ilG: by l 'intermediate the terminal J of lo \ il8TO (;: \ so that what has been exposed above $ f ;;; U $ for the great group 1 ".B.5 <,, When, 1st

  <Desc / Clms Page number 43>

 final selector is stepped up to the first line of the group, the CER relay is actuated via terminal JG, the test via each line of the group then occurring.

   If all the junction lines are occupied, when the last line is reached (position 1), the fact that the CH relay has fallen allows the switch to advance step by step to position 2, where the CE relay is bypassed via terminal S and stops the movement of the switch, at the same time as this relay causes the relay CHS to drop in order to return the busy tone to the calling party. This position 2 is left without connections on the other banks, so that the CH relay cannot happen to operate. It is necessary to leave this position unassigned in order to allow the discrimination necessary for counting, as will be explained later.



   In each of the examples described above, when a free line is encountered, the called subscriber causes, by answering, the operation of the relay CF to interrupt the. bell, this relay thus completing a circuit for the CD relay.

   On the CD1 contacts, the CD relay opens the circuit of the CER relay which falls slowly, while at the CD2 contacts it completes a continuous circuit between the CFS3 or CFS8 brush of the final selector and the CLF3 brush of the line finder, in a object which will be described later with regard to the input selector of FIGS. 13 to 15.

     When the CER relay drops, the CER4 contacts apply the potential of the return earth through the intermediary of the valai and of the CLF4 bank on the counting conductor M, this earth potential being taken by the intermediary of contacted CH6 and CPU5 on the CFS4 or CFS9 brush through the S, J, SG or PBX terminal, the terminal used /

  <Desc / Clms Page number 44>

 
 EMI44.1
  # ':' l-: e "el ': 1X1.t of the kind of 13. l 1 ù g7 .¯.: tiu'ûZ. ^ .: ï'; 0.

   We C '{3YiJ.31'qiJe- for 1, #: junction lines, where we .'1,' 1t: t l. i ;;, none è.Cf. ) O.1 "'166 S; i 5 G or,' .. z'v.? To., I. 1 '(-'e s': 1t'li,: l, 1, Cln circuit of G, C; ilA) n, G t: .l, jÎ.t gives that iC): Y'C.4'C ': i.Gr du l) O; tc central principala.l does not register any compulsory tax for CE :: :) 0,1) - l) S.Lf :;, In C which concerns m21tent the Q5¯.GC:. 'r, y.i'tGG =., ± CO> (1i ".; io: r '!,. 1) O;:; ;-) ilJ1E;) of E' .1 â;. The?:: L. o i of the circuit, O '' - see that if .s ".iî0:" - ,. caller hangs up or fails to send Ui 's 1 ir <.a 1 (j)) 1'è :::: - i s ï; li. '. 7.Oi 'of 1! 1:., - (iti11) .m of EJ .ï; 0-; i 'ii11}) l; .1; iOï,) tone 8 ::::' ïC '.: E:;: c o r?. e. j> c; fl d i n:}. "li.

   I) çenli6 '"L" c11if: f "co, Icruque the final exe 1 ec - tor 1 xt te 1 fi the position 45, the potential of 13 earth; 2," 3, PJ? 1:' Lq1. : .e by i.?.i'%E;)i>zl'Ci.2.7.;rG CW la boa # ne JG and de: 8 contacts! '10: 4 fQ? .t151 OF1, G L1îi8 and Cù - 2 to cry 1 iil3.N.) (3U-V:;: e of relay CTZ. Ej- 'fot' '. Ction- <'.. 3..nt, this relay CTZ deo1 "9", crle, 6 1 11' the connection, C ': 2Z3, the relayB C]'} I which 7. eL, OT, turn makes tonl08r the 1'8- ta.ot.:,. CTZ3, CFH relay which turn f'j.it fall Z., -t, i. 1 <1 ± 'E; and cut 0 .'3.71r the c O'lilJlHl'r [j, C 'and i 0'-, on the ± side of the circuit :: "it; u (on the side {of the dema.J'1deur station, t- Tridis, il; '!;' le:;. CoiT.tccts OTZ2 and C1'Z4 i # a?> Ô.ei; ± the circuit against 11 "- :(; occupation.

   The u0:? 4-3.G0 s G I Z 1 complete U! J circuit Ô. ' e, 'tl': lîy, Sli1e.'tà inter- ruption n.uC'rilv.'G.CJu4 for 1C, -. (: C '' 'CO-2..17î ..' tY 'CFS:' I è, from) G'4fï''ït,:!. 1 d the earth collected by the interior of the bo ;; ne:, at the. ouite of which the i61ecteuv fi - '' al makes E; e: ;; turn quickly â.nj, C7, lâ 1> ixr the entire length of 1.> iir: banks up to cl0.N; the PO \, -, j, ti011 of rest 1 where the return circuit T. 'opens.



  : D8Y ": 'the case where the calling party cuts off the call Ijgf1e during' .5 (: Iilj, C., '1C7: of the second digit of the number, or omits" to send a sj4f;: f' 8.1 for'le i-3ieco:; "\ cl digit of the harsh number issued:, 1on of the number maJ: li1l1} .m of seven 1.:,ïLi,.M,Oiï ;, of .to: r <a î 1. ij <F; when, the relay at G 9.Ù enters e, at. : uQ "l: cvrv. '?. 1.1 in action
 EMI44.2
 to advance the final selector step by step after de-
 EMI44.3
 }; J2:; ';;.' Ement of the last line of the group which ensures the connection

  <Desc / Clms Page number 45>

 
 EMI45.1
 xion either with the / S terminal or with the J terminal, the CTZ relay is activated through the S or J terminal and the CPU5 contacts.

   This relay cuts off communication as
 EMI45.2
 this has been described above, and the final selector advances to the rest position, and during this time the circuit remains kept due to the holding of the CTZ relay. CTZ1 contacts are used to keep the CTZ relay actuated
 EMI45.3
 j 1.H? tl'l 'until the sweeps of the switch reach position 45, after which it' !: maintains it via the Joz terminal until, until the rest position has been reached.



   If the called subscriber hangs up after having sent the second digit of his number, and either before or after) this called subscriber has answered, the CTZ relay is actuated from the. earthed terminal and through
 EMI45.4
 contacts Cr'1., CJ! '1 - ". 4, CFD5 and CES.



   If the called subscriber hangs up after answering, the CTZ relay is actuated through a circuit which begins on the earthed terminal and passes through
 EMI45.5
 contacted them CFR6, CD1, CT6, CFD6 and CES.



  In the cut-off conditions realized by the time impulsioae, that is to say if the cox xerr; 01dart desman- deur completely forgets to emit a signal or to racor '') - dear after it n. ' has received no response, the CTS relay comes into action under the effect of the "s" pulse through the conductor 16 and one or the other of the $ contacts
 EMI45.6
 G3Dl and Cet1, After a period of a duration of the order of 30 seconds, the "Z" pulse transmitted through the intermediary of the conductor 17 causes the manoetzvxe of the relay C ^ 1Z to cut the circuit as has been described above.



     Below will be described the circuit of the input selector of the tandem exchange shown in the figures.
 EMI45.7
 1S to 15, this selector operating according to the same e8ff1: n ...

  <Desc / Clms Page number 46>

 
 EMI46.1
 geneviux cipes that the selector to. ten J. j &) 1e ,; des' figure 9 and 10, m3.hJ with possibilities uUlI1.> the element ': lh'e1 as a result of- the obligation to re' .1 l il: 1 e: r, a cûumtznicrt.on uvee of the cen- traux é1ojgn0: iJ.



  There are '1, three main types ii ") jJj) eÎb3, Vo; 0ïb1eo -with this selecteiir, to have: a) leu called come from the main exchange where the cent1' '' 31 conl:> idpré eit ., J1) OOl "\ 1 (; (tnÓ and which are <lesti- .ned to a subscriber or. a junction link: lcce; "i1) dcpuie 1.ia; :: 1 <.īncx of the selector, this selector 'coming into action under the effect of a nl; lllfr0 to. two cipher cl'Jn: 3 the C7t e; 3 lineage ('; 1good () (; J and a 11111110 Y.' 0 - 'a single digit donations leo 0') (; des 1 ïC:., de j unction; b): 1'1) 1) e1 $ from the cé: <; 1t =:> 1 in tandem 10c'.11; c) calls from centnux 61oign6.
 EMI46.2
 



  1-'on .. simplifjer 13. de: jnrjption, we will add that the centrrl in tindem conjidt1'é is directly linked :: tu cen-tral yxircü? R'- and is constituted p'n "exenjple by the ce >: t ' <.Til this 1 ?. figure 2. In the cjw of an incoming call coming from the central 'pr1nnip1, the established loop of which, the forward direction by the operator via deu junction conductors SI and 80 (figure 13) causes the operation of the relay DA in
 EMI46.3
 ncrie with the it> 1.-ii> i differential. 1 ',' h .. which, this time,, 'exe1' - this no action, this rJ1 '; 3.ne01; Vre Being followed P'}! ' the relay DB (figure 14) which, in good turn, causes the. Operation of rEiaiy DC (figure 14) and DOVR (figure 13), the latter relay then actuating the rel'li; DG (figure 14).

   On let "non- t: 1ct DC4, the DC relay provides a pulse circuit for the electro - ', iw) nt vertical DV1: I, t'3, ndi", that,!' ;; 1) Y . the contacts D & 2 (figure 13), the relay DG occupies the!: 1 (the input lever of the main end to be prevented On ac6 & à> Jz the intermediate or center in t2ndem.



  As a result or because of the system adopted for the

  <Desc / Clms Page number 47>

   numbering of the tandem exchange, system which has been explained above, levels 1 to 6 of the selector will be affected! to local subscribers. Consequently, if one of the digits 1 to 6 is selected, on coming into action the relay DA transmits pulses on its contacts DA1 to the vertical electromagnet DVM through the lower winding at low. DC relay resistance, so as to raise the selector brushes to the corresponding level.

   During the pulse train, the rela.is DB is intermittently short-circuited and is kept actuated, the battery supply arriving on this relay via the resistor DYJ extending through through the DMRA straightener to minimize any shuttering effect on the DVM electromagnet. During the first vertical step made by the switch, the set DN of springs removed from the normal position is actuated and on the DNI contacts it short-circuits the upper winding of the DC relay to allow it to remain actuated during the stroke. the passage of the pulse train.

   At the end of this train, the DC relay drops slowly, and when it drops, the DCl contacts (figure 13) apply the earth potential through the DAW vertical brush on any of the positions 1 to 6 of the DAB vertical bench to trigger the operation of the DE relay. By functioning, this DE relay removes, on the DES contacts (figure 14), the short-circuit which existed on the upper winding of the DC relay, thus having the effect of making it come into action. again and thus complete at this time a pulse circuit going up to the rotary magnet DRM of the selector via the closed contacts DC4 and DE2.



   When we. selects the second digit, the brushes advance step by step on the selected level, the DB relay is now actuated as before. At the first step

  <Desc / Clms Page number 48>

 
 EMI48.1
 of rotation, the DNR set of reseort; rotating away from the normal position E: f> t actuated mechanically and again, on contacts DNR2, the upper winding of the DC relay is shorted. At the end of the pulse train, the DC relay drops slowly as before, and when it drops it opens the DE relay holding circuit. on the DCl contacts, and this relay in turn falls slowly.

   At
 EMI48.2
 court'; of the DE relay drop time, a test circuit is completed for the relay. DH (figure 15), this starting circuit
 EMI48.3
 from the terminal to earth and passing through the, DC2 contacts, the DH relay windings and the DC3, DAR5 and co: ntcty. DB6 to end on the P.



   If the called line is free, the DE relay enters
 EMI48.4
 er action and, on contacts DE3 and DH6 (figure 15), it establishes the continuity of the. incoming trunk line, via the DQA and DQB capacities, jvx.que iir the line of the requested subscriber, the operator not receiving in this case Üonalité. The operator can alo: r! ring the desired Q2YJt correspon- dence by applying in the 1, set before, through the intermediary of the junction line, a signal constituted by an imbalance of the battery, causing the effect of which the relay
 EMI48.5
 DA eHte actuated, and the DPC relay comes into action.

   Under the effect of this maneuver, this relay causes, on the DPC2 contacts, la. maneuver of. DNC relay (figure 14) which, on the :, DNC1 contacts (figure 15), causes the operation of the
 EMI48.6
 1. 'DRR, 0. la. as a result, on the DRR1 e: DE: 2 contacts, the permanent ringing current is applied to the called line via the conductor C'J: i7trn; X'i% and the 9'c: : s'> i; tal ^ Ce DYO.

   Aln'È: 8 a short application of the current of;, on, r¯, z.ie, 0 "'1 removes the, ignt11 of imbalance, which has the effect of Ql" e 101'i> that the subscriber de & iré picks up his headset he can enter into a conversation with the attendant through the input selector circuit which is kept constant.

  <Desc / Clms Page number 49>

 be a local access from the tandem exchange as long as the attendant remains online. When the called party answers, the DD relay (figure 15) comes into action and, on the DDl and DD2 contacts, it reverses the battery potential applied through the DA relay on the junction line in such a way. to give a control signal to the operator.



   If the desired correspondent is busy, the DE relay does not come into action during the period of slow fall of the DE relay, therefore when this last relay drops and again activates, because of its fall, the DC relay by suppressing the short circuit. from its upper winding on the DES contacts, the busy tone is returned to the attendant through the common conductor 19, the DHS5, DH4, DVR1, DC6, DNR3, DE6 and DAR5 windings and the DA relay windings .



   The attendant can now offer the call to the busy party by applying an imbalance signal from the. battery, which activates the DPC relay, which in turn causes the DNC relay to operate, This time, as the DE relay is in its normal position, the earth potential is applied through the DOVR4 contacts, DNCl, DD3, DH2 and DOS, to trigger the operation of the DON relay.



  This DCN relay is locked by means of its upper winding and maintains, on the DONS contacts, the DC relay as long as the imbalance signal remains applied. On the DONS and DCN4 contacts (figure 15), it establishes the continuity of the junction line, through the DQA and DQB capacitors, up to the desired line.

   The correspondents who are in conversation are then invited by the operator to hang up their headphones, and the imbalance signal is removed from the trunk line, which causes the DPC and DNC relays to return to their

  <Desc / Clms Page number 50>

 
 EMI50.1
 j) od.tio, '1 normal, while the relay D'11 annuity maintained.



  A new application of the complete imbalance signal ', '10: 1.'8 a cut-off circuit, .and, when it comes into action again, the DNC relay applies, & on the D15Cl contact, the full lesion of earth through the broom and the
 EMI50.2
 'bench P to drop all the & cut-off relay already connected at this point. When the imbalance is removed, the DH relay comes into action, through its in:

  series, in the usual way, and a new application of the imbalance signal causes the maneuver
 EMI50.3
 of the rel'3.i $ b9àl for the application of the ringing current to the set of the requested subscriber, as has been described above.
 EMI50.4
 When, at the end of the coY> ver,> a:

  tiooei, the operator cuts by removing her call card, the earth potential is momentarily applied in an unbalanced and automatic manner to the. line, which has the effect that the relay
 EMI50.5
 D1JO kicks in, ma.ie. no. not the DNC relay ... consequently, on the DPC1 contacts, the DOVR relay drops out, and, when removing the imbalance, the :: DA, DB, DG, DCN and DE relays) drop in turn.

   For the DRM electromagnet, it $ 'establishes
 EMI50.6
 alo7; an automatic control circuit, by means of contacts Dl #, DHR7, DGP1, DH2, DE ?, D: F # m, DAR1, DOG? and D; '7, to terminate in the earth by the intermediary of the delayed warning equipment, connected to the conductor 82 which is separated from the benches, after which 118 fall and turn eii-de5'-: :: or ;, benches under the action of the. spring tension by returning to their normal position where the DN2 contacts away from the normal position open and disconnect the drop circuit.



     When the desired line is part of a group
 EMI50.7
 : ...:., you can get on the selector the. ability to perform the scan according to the syetem.e P, B, l ,, and for this purpose the

  <Desc / Clms Page number 51>

 first line of the group is connected to the voltage of the battery in bank H, and the last line is to earth.



   Therefore, if we select the first row of a grou. eg P.B.X., the DES relay is actuated by means of its lower winding and the brush and the H bank when the DC relay drops. If the first line of the group is occupied when the DE relay (figure 13) drops and allows the DC relay to come into action again, the earth which arrives through the DC2 contacts is applied through the input. upper bearing, low resistance, of the DHS relay and DHS2 contacts to re-energize the rotation solenoid
DRM. (Figure 14). At the same time, the shunt provided through the DC2 contacts for the lower winding of the DGP relay is removed, so that this relay - is connected in series with the windings of the DH relay.



   When the DRM electromagnet is energized, the switch brushes are advanced step by step to the next position, and then, if this line is free, the DH relay comes into action and disconnect, on contacts DH8 (figure 14), the circuit of the rotation electromagnet, operating for the rest in a normal way.

   If this line is occupied, the DRM electromagnet, by actuating its DRMC switch contacts (figure 14), completes an excitation circuit, for the DGP relay via its upper winding in series. with the upper winding of the DHS relay, and the DGP relay opens on the contacts
DGP1 the circuit. the rotation electromagnet, as a result of which, when the electromagnet falls, the operating circuit of the DGP relay opens through its upper winding, - while when the fall of this relay the circuit of the electromagnet is completed, and the brushes are advanced to the next position.



   The interaction between the DGP relay and the DRM electromagnet

  <Desc / Clms Page number 52>

      continue until you reach a free line or, alternatively, the last line of the group. In the latter case, the DH relay does not come into action as usual, but the DGP relay then maintains itself through its upper winding and the DYN resistance from the earth potential collected by the brush. H, avoiding
 EMI52.1
 :: i ,,, 1 a new excitement of the 6lect: co-aima, lt DRM.

   The DHS relay, which $ 'is kept operating between their pulses
 EMI52.2
 during system scan operation ë.B.X. , due to its delay in falling, falls held and opens i, 'àixtie p? ¯i = t, s; uz <lex: co> ita.cts DE-52, iiicùit coi> i #.> ia; nô.e 1 on the other hand, on the DIT-S2, the conrn12 circuit, nde: of the electromagnet, while. 1> iir 'les: contact DHS3 it opens the relay circuit DG9 and that on leo: contacts DE31 it opens the test circuit of relay rH. On the DiI5 contacts, the busy tone E'kJt é107: 'w returned from the common conductor. 19 to the attendant.



   If we select an output conductor by its
 EMI52.3
 number 8 or 9, to connect a 8.boY1 " <, é of one of the 1 e s exchanges; .J 1 1,;, move away, one 'sees that due-moment that.? levels 8 and 9 of the vertical bench Da1i3 (figure 13) you ODt connected on the left side to the DAR relay, this relay is activated at the end of the vertical movement by means of the DCl contacts when the DO relay drops, while the relay DJA is in a normal position. The DAR relay is locked by the intermediary of its DARA contacts, while it opens the circuit.
 EMI52.4
 of # = elL;

  .i> DC on the DARS contacts (figure 14), that on the DAR1 contacts it completes a self-interrupted drive circuit for the (read :: o - ',: dma)' 1t of DELI rotation, and that on <contacts D, 1R3 he connects the relay, for test DHJ (figure 15) on the brush P instead of the relay Diz, Scanning for the discovery of a lie ,. de onctio with the central neceE; o, i:

  (, 'e or request' Or with the exchange in tandem neighbor on the route that must be followed to reach the

  <Desc / Clms Page number 53>

 central terminal necessary then occurs, while all unassigned outputs existing in the level are earthed on bank P,
If a free output line is reached, the DHJ relay (figure 15) comes into action quickly to stop the rotational movement, by opening the DHJl contacts (figure 14), and on the DHJ2 contacts it initiates the operation. of the DHR relay.

   On coming into action, this relay is locked by the intermediary of contacts DE: 8.4, while on the other hand it disconnects the circuit of the electromagnet DRM on contacts DHR7, and that on contacts DHR1, DHR2 and DHR3 (figure 15), DHR5 (figure 13) and DHR6 (figure 14) it establishes the continuity of communication through the negative and positive ST conductors, H and SW, up to the reset circuit. - tandem whoopee of figures 16 to 18 which now ensures that the call is maintained, as will be seen below.

   By switching on, the DER relay causes the DA and DB relays to drop, but the DOVR relay (figure 13) remains maintained via the DG3, DOVR2 and DHR5 contacts, as well as the brush and the bench H which are at the potential of the earth that one meets in the repeater circuit in tandem and which thus maintains the relays DG and DAR. Under these conditions, it is seen that the selector acts as a group selector operating in a normal way, the continuity of the junction conductors 80 and 81 being established by means of the switches without any transmission bridge with the repeater circuit in tandem.



   If no free junction line can be found in the selected level, the brushes rotate to the position of step 11 where the spring DS of that step is mechanically actuated and the DHJ relay (figure 15) enters. action in series with the. -. DYQ resistor connected to the bank contacts of the 11th step and actuates the DHR relay. The DA relay then maintains itself via the eleventh position.

  <Desc / Clms Page number 54>

 tion. banks negative and positive, while the contacts DSl (figure 14) of the eleventh step return the busy tone.
 EMI54.1
 patio through contacta DAR5 and common conductor 19.



   During an outgoing call from the exchange in tandem RE, when a local subscriber selects the corresponding number 7
 EMI54.2
 aux li /:;, ne ,; outgoing junction for the main exchange, the CH relay (figure 12) of the circuit of the local
 EMI54.3
 connection between ùio.n.ù the circuit via the conductor 1 'of the set of conductors which is connected, at the bottom of figure 13, to the DP relay in parallel with the resistor DYE . In action, the DP relay causes the operation of the DOG and DRT relays, the latter being slow to start.
 EMI54.4
 trer in action due to the e; ir..Jçai1ce in series D'1,]) and 1 [} bypass capacitance DQ, C.

   Slitting ia. period of excitation, a ringing pulse is applied forward from the common conductor 22 and through the
 EMI54.5
 junction conductors 80 and 81, to occupy the equipment at the far end of the main circuit of the junction device. The ringing which sounds under the action of the local connection device is interrupted because the. drums
 EMI54.6
 Cf; Jt connected in. 1 through the. resistance DB (figure 13) on the negative input conductor.

   When the operator inserts her answer card into the jack on the
 EMI54.7
 call junction, it i "ensures the number of the called party and at (;,:.,; i. that of the de10nc10c;. ::: .. the verification title. roux 'obtain the verification., the operator will have the
 EMI54.8
 of:.:; 1) -. "To select in return c: fl direction of the input selector. To obtain this result, she introduces aa file
 EMI54.9
 call into the multiple jack of the calling junction line, or alternatively it reverses the verification key.

   In the u'r, and the other case, the circuit conditions

  <Desc / Clms Page number 55>

 in the main exchange are such that it is a momentary imbalance of the battery which is applied through the junction line and the contacts DOG2 and DOG3 as well as DRF2 and DRF4 (figure 13) up to the local connection device through which the call arrives.

   Under the effect of these maneuvers, the CPC relay (figure 12) is energized and applies the potential of the battery through the brush and the CFS3 bank and wire D to cause the DSC relay to operate (figure 13). ). On coming into action, the DSC relay causes the actuation of the DOV relay which, in turn, actuates the DOVR relay and also completes a local operating circuit for the DA relay (figure 14) via the DYG resistor. , after which the DB relay also comes into action, followed by the DC relay.

   On coming into action, the DOVR relay disconnects, on the DOVR2 contacts, the initial operating circuit for the DOG relay, but the latter relay remains maintained by the intermediary of the DOV2 contacts until the signal from imbalance has been removed. When the signal ends, the CPC relay (figure 12) drops and causes the DOV and DOG relays in turn to drop, the DSC and DOVR relays remaining maintained via local holding circuits.

   Returning to his position. normal, the DOG relay now actuates the DG relay (figure 14) and also reconnects the junction line 80, 81 to the DA relay which, now, through these lines, maintains itself, the func- tion. - operation of relay DG having had the effect of disconnecting the local operating circuit of relay DA on contacts DG5. The drop of the DOV relay also provides a local holding circuit which passes through resistor DYA and through contacts DOV4 (figure 13) for the local connection device on the requested side of its circuit.



   The attendant then selects the rest of the number

  <Desc / Clms Page number 56>

 
 EMI56.1
 which includes the two digits which are necessary,;. ', a. the establishment of a communication with the subscriber of the central office in tandem, and the input selector adjusts this accordingly, the relay DC being maintained during the whole duration of each train of pulses in the usual manner. Note that as soon as the DSC relay is actuated, the normal DH relay test circuit is cut on the contacts.
 EMI56.2
 LSC3 (figure 15), and in its place a circuit 'e5t prepares for the relay DVR through the brush RN.

   At the end of the second pulse train, the DO relay causes, when it falls, the slow fall of the DE relay, and during
 EMI56.3
 this te1úIA ;, drop the voltage of the battery ezt applied in return, through the resistance D'YK (figure 14) as well as qUt, contacts DE1, DC7 and DOG.ô, and by the inter - through wire D and the local connection device of figures 11 and 12 through which the call arrives, on wire D of the circuit of the calling party's line.

   From
 EMI56.4
 this wire, it extends to the bank pàl (figure 15) of the input selector, the local levels of the negative and positive banks, P and EN in the ISM multiple of this Detector being respectively connected to the banks negative and positive, a P and D of the local multiple LYàI of the line finder of the local di.poitif of licieor, Consequently, ei the number given by the requester is exact, the potential of the battery applies to the 1 D ; wire / propagates through contacts DBC4, DAFs2, bottom winding of DVR reiaix and LC2 contacts to earth.

   This therefore has the effect of activating the 'E1aie DVE which is locked by means of its upper winding: ch: ur tandie, tlur contacts them DVR1, this relay sends back a verification tone by the inter-
 EMI56.5
 mediary of the common conductor z4 to. the operator, which has the effect of causing the DB relay to drop and the DC relay to restart. where the number is not correct,

  <Desc / Clms Page number 57>

 the DVR relay does not activate, so that the operator receives the busy tone. through the common conductor 19.



     'We see that, in this case, the operation is of a quality equal to that obtained in the case of a P.B.X. The usual automatic movement takes place, and this time it is the DGP relay which tests the circuit with the DVR relay through the EN brush until it is reached. caller line marked. The DGP relay is then retained to stop the rotational movement, and the DVR relay operates as before for the verification tone return. If the wrong number has been given, the selector turns to the end of the group, and it returns the busy tone.



     '' The verification signal, of the fall, which is initiated either in response to the withdrawal of the calling card out of the multiple jack of the calling line, or under the effect of the return of the verification key, in its normal position, consists of the momentary application of the potential of the earth on the two wires of the junction line. Under these conditions, the DPC relay (figure 15) comes into action again, but the DNC relay (figure 14) does not come into action again, since it is now in the short-circuited conductor. As a result, the DOVR relay holding circuit cuts out on the DPCl contacts (figure 13), and then drops out.

   When the imbalance is removed, the DOG relay is re-energized by means of contacts DP5, DOVR2, DHR5 and DPC1, and reconnects lines 80 and 81 to the calling subscriber via the initiator. - initial nary and of the local connecting device of figures 11 and 12. At this moment, the relays DG, DA, DB and DO toril- tate and initiate the return of the switch brushes to their normal position.

  <Desc / Clms Page number 58>

 
 EMI58.1
 If the subscriber overrides by the corresponding requestor
 EMI58.2
 was Tjyanohb;> ii a central é 1 o: 1 ù born used one that
 EMI58.3
 has just been considered entrusts a centra ,! in tandem, we obtain
 EMI58.4
 holds them :! conditions of elect1o in return oor & ne prucedem- ri'n.'nt.

   After having established and having cut the oppel of véi: iTica.- tion with the corre .-. Pod.3 ''. T claimant, 1 'o ¯ = a é i; ;>: t 1 E, c introduced ,,, :), :: '10he call rà a n 1> 1 e j ja.ck multiple of the call line, and u momentary balance:; .?., lor & '±> é; .fii to provoke:;', 1 .'.-... ". work of relay LQ" V, DOVR, DE and DO. When the;, E, g: ial e terminates, leu 'relays LOV and LOG- to'bnf co>: ... io that has.:' - 0:: i cr i't '1 l 1. -; >. e = :: i *, a la i i iL t ;; d. what the e .o, #: j. :,> i;:. ii to e; i - .t i; : -. x ..i a. c t f. o ::> C '", the 1 1 g: n e' of junction is bl'3..ï, e :: lied again # :, 1 ?. 1. ' the e 'L' e 1 O. i DA, the Sun .: <locul p0hiitive of S1 E. -i. L: 1 3., ". J: i, 1? Which ar-rivc the p & l. {; Being maintained this time in the ha.bitut .-. Lle manner.

   The operator e s é 1 e c t 1 o <h.i.i e z>, i o - <the desired number cil. input selector, to obtain 1: .c e 11; x> junction line which extends to the central or in the direction of o L <.. <. "ù t. J .l takes away duaire.
 EMI58.5
 



  If Oi1 supposes that the exchange moves away 111B (figure 2) is the desired exchange, one 8elBction the figure 8 da! 1: "the M6- entry reader of the central 2ii to have access to the central RD. Ai ' "", i as described above; s airlock, the 5elE: input side advances step by step lnSCjLt'8, i level e, following which, 101 '::' of the fall of the DC relay, the DRR relay is activated and initiates an automatic search maneuver by a rotational movement üEvt xu: o the selected level. Qua.d 011 finds uz: l ;. li = à; ie unoccupied, the DHJ relay (figure 15) comes into action by means of the brush and the bench It has the effect of the marking voltage of the battery and by the intermediary of a resistance as 2Yl t: ii; tt'8 18) ta. <is the pepeeter e / 2 tti'ld8'iM C.:#,NOCàC 'the unoccupied junction line with the debit central: eé.

   On entering into action, the DHJ relay initiates the operation of the DRU relay which establishes continuity.

  <Desc / Clms Page number 59>

 from the conductors to the tandem repeater which, as will be explained later, maintains the call.



  The DA and DB relays drop when the DHR relay comes into action, while the DHR and DOVR relays are maintained by earth potentials returned by the repeater circuit in tandem through the banks and P and H brushes, and that the DOVR relay maintains the DG and DAR relays.



   Under the effect of the selection of another number 9,, necessary to obtain access, from the central RD, to the remote central RB, and under the effect of the selection of the final number necessary to the establishment of communication. with the desired subscriber in the central office RB, pulses are transmitted to the tandem repeater of figures 16 to 18 which renews them via the junction line with the central RD where the number 9 has the effect of y set the input selector to the level which gives access to the central terminal RB.

   The final digit is repeated by the action of the repeater in tandem in the central RD associated with the junction line from the central RD to the central RB and is used to set the ten-line input selector in the terminal exchange. RB to ensure communication with the requested party.



   When the called subscriber answers after having been warned by the ringing by the operator, there is a reversal of the direction of the battery potential, through the junction line, and from the repeater in . tandem of the central RD and that of the central RE, In the central RE, the repeater then repeats the reversal maneuver up to the operator and also prepares the application of an earth potential via the conductor ST starter which leads to the broom and the ST bench (figure 15). By receiving the signal constituted by the battery inversion, the attendant connects the subscriber

  <Desc / Clms Page number 60>

 requestor on the requested subscriber by the shortest path
 EMI60.1
 ie via the tandem exchange RT ;;

  , and this by applying a signal obtained by the imbalance of the battery via the function line 80 and
 EMI60.2
 61. The signal propagates forward through the tandem repeater of Figures 16 to 18 which then, and as will be further described, connects earth to the ST conductor, from which it is applied by the intermediate bench and broom ST (figure 15), of ;; contacted DHR1, the windings of the DOR relay and contacts DP6 on the battery via the DYP resistor.

   The DCR relay comes into action through this circuit and turns on.
 EMI60.3
 rust i + 1? the DCR1 and DCR5 contacts, and applies, to the DCR2 contacts, the earth potential via the brush and the wire bench to ensure the operation. The ERN relay (Figure 18) in the repeater SO1é5 causes this effect to rotate the associated seeker. The DCR relay, on the; DORS contacts (figure 14), also applies the battery potential via the resistor
 EMI60.4
 Dol and riliis DRO connected in parallel, and contacts DG6 (figure 13), on wire D and via the local connection device used for the call, to mark or locate the calling line.

   On reaching this mark, the tandem repeater seeker stops and thus completes a circuit between the calling and called subscribers. The relay.
 EMI60.5
 DHî; :) (figure 14) works in series with the upper i: r.rouîctz: e? I, with a resistance of 11 ohms, of the test relay EK
 EMI60.6
 (figure 16) equal to. the circuit of the tandem SA seeker, the SV bench! of the tandem searcher giving access to the conductors D of the various subscribers of the local tandem exchange RE.

   On C'OY1to'ct ;; DRû1 (figure 15), the DRS relaib drops the DI-? Relay, while & ur the contacts !.) DRS5 it opens at one point the DCR relay locking circuit, and that, on

  <Desc / Clms Page number 61>

 the DRS2 contacts (figure 14), it causes the DCN relay to operate, so that the attendant is again connected to the DPC and DA relays and is connected to the conversation circuit of the abundances via DQA and DQB capacitors. The DA and DB relays come into action again, thus providing latching circuits for the DCN and DG relays, while the DOVR relay maintains itself through the DPCl contacts when the DER relay drops.

  * At the instant of breaking by the tandem finder, the earth whose potential arrives via a weak resistance, and which has been applied in the forward direction via the winding lower, 8 ohms, of the EK relay (figure 18), of the ETH5 and ETH10 brush and bank, and of the H bank which is connected to the normal conductors. line circuits of local subscribers, maintains the cutout relay in the line circuit of the calling party, and at the same time causes the forced fall of the local connection device initially used by this subscriber, following which the relay.



  DP, DRF and DSC (Figure 13), DCR (Figure 15) and DRS (Figure 14).



   The attendant remains connected to the repeater in tandem via the DQA and DQB capacitors until she has confirmation that the conversation has started when she wants to remove her answer and call cards, which causes the cutting of the junction line 80, 81 with the central RE and consequently the fall of the DA, DB and DON relays. An unbalanced and momentary earth potential is automatically applied to the junction line when the call plug is removed, which is used to ensure the operation of the DPC relay which, on the DPCl contacts, causes the relay to drop. DOVR (figure 13), which in turn drops the DG and DAR relays,

     after

  <Desc / Clms Page number 62>

 This is completed by a self-interrupted drive circuit for the selector DRM rotation solenoid, while the switch returns to its normal position.



   A call which originates from a subscriber branched into a remote exchange, and intended for a subscriber branched onto the tandem exchange or another remote exchange connected to this tandem exchange, generally obeys what has been stated. in detail above.

     From what has been said about figure 3, we see that if RD and the remote exchange in which the call is made, if a trunk line is then occupied between RD and RE, that it is assumed to be a tandem exchange in which the switch of figures 15 to 16 is located, the tandem repeater TRI associated with the junction line concerned makes its searcher TH1 perform a searcher maneuver in order to find a input selector which is not already used either by the tandem exchange or by the connection line with the main exchange.

   The input selector is accessed through the THM Tandem Multiple Finder Finder (Figure 13), and, if not already in use. the input selector, the cut-off relay associated with the tandem finder, causes the connection to the DP relay which comes into action and causes the operation of the DOG and DRF relays, following which the buzzer sounds in the main control panel of the manner which has been described above in connection with a call originating from a subscriber of the exchange in local tandem, However, in this case, as each input group is assigned a relay of the minor type like the re - left DJA (figure 13), this ADI relay comes into action, in this case, via the conductor H,

   and it is used to indicate the particular group of trunk lines through which the call arrives,
Selection in the opposite direction by the attendant and subsequent deletion of the communication line with

  <Desc / Clms Page number 63>

 the attendant are done in the same way as what was explained above, except that, when the attendant reverses her key, the searcher of the tandem repeater through which the call arrives turns to search for the trunk line or the selected subscriber, instead of the calling subscriber as in the previous case.

   If a subscriber attached to the local tandem exchange is called, the operating circuit of the relay is inside the selector and passes through the contacts DOVR4 (figure 15), DNCl and DD3, of the windings of the DCR relay in series and DP6 contacts to pass to the battery via the DYP resistor, the DD relay having been actuated when the requested party answered, and the DNC relay coming into action under the effect of the voltage unbalanced battery when the attendant reverses the key, The:

  , conditions for starting the tandem finder are provided.) via the DCR4 contacts (figure 13) and the conductor SW j to the corresponding bench of the repeater finder in. tandem, .la.? - say that the locating, by the battery voltage, for the searcher is provided by the DTL resistor and the DRS relay (figure 14) as well as the DCR3, DSC6 and DH9 contacts and broom and SW bench.



   If the selected trunk line is in the same group as that of the initiated call, as it would be if the call was made from the central RD to the central RB, when the vertical broom DAW (figure 13) reaches this level , the DJA relay associated with it will already be in the maneuvering position.

   Therefore, instead of the DAR relay which is actuated as described above to initiate the automatic rotational movement, it is the DOG relay which is actuated again to send the call back through the system. intermediary of the communication line. On the DOG1 contacts, this relay applies

  <Desc / Clms Page number 64>

 
 EMI64.1
 Cllenr: lt a potential of the battery by the i'J '; e: ciiJ.8dh1.i: rf.J of 1 ar é x 1 ota;> c DY:' and clG8 co, .to.ct0 I70Vcl, D: 3, Zou1 and DJrl3 until jur the 030C Il of the tandem seeker, and a 0iGa (.,;. I; '.1i'-it: ca.Y1GîÜi;., Via the broom of the tandem seeker bzz li to indicate to the school .... Hte \ 1.J. 'e t3.:'!deül ql:' the call ::

   0. "'' W: ^. Te N in court ,,, of execution, and this 1 J. there ca 0 :. turn for 8effect of applying the, d; '1al cortLil ...) D ,: C the potential of .1 (:;: r.:c d which! IJ 2 'E:.-7 u'. The 1 st \ t: 1.1 al el 0 iLS (té 1) 0 uc aB. \ Á 'e dn, f ;! ce iiei.fl1osr the Î) O, ncheme'1t du: iC ::. t; CtClil.'; ^ C ';.' E;: 2tGC, Si 0 .. "' . e7.fj,; E, 'C ï (l, i) ltena': '4 the repeater circuit e "to.)' '. den1 of. $ figures 16 a. 18, we see that as well as the mon - tye the new toex devices <10C ;; this system, the circuit fo "c'io''1 {le of different i.0.:, and it is ;; éce> * aii" é> de, De r $) 1cl: 1. "e cornpbe of its 1? o8itio: -1 el 'ue fo.çor1 perfectly Câ.a7.sG dcZ'r1¯N the soul / iasement of the li'8, 0pécialeiî10; 1'b eifl what concerns the entry scleoteur Figures 13 to 15.



  The junction line 90, 91 (h) '"),) the left part
 EMI64.2
 of figure 16 is connected to an exchange which can be
 EMI64.3
 Either a terminal exchange or another exchange in tandem, but in either case it is more distant than the immediately superior central exchange. The uniselector which is tandem keyer in the right part of the figure gives it access, through the multi-device there to the Nuite devices 10) the junction lines to the main central, which can be direct.:! or go through another exchange in tandem; and on each of which e; t
 EMI64.4
 connects an input selector.
 EMI64.5
 



  2 j the repeaters of the local tandem exchange, which serve for other remote exchanges associated with this center, a1 in tandem.



  30) leu centra subscribers ,! in local tandem.
 EMI64.6
 



  Access, via multiple device

  <Desc / Clms Page number 65>

 ICM (figure 18), is done from the level of the input selector which corresponds to 'this particular group of trunk lines, while the multiple of input THM (figure 17) ensures the connection with the banks of the researchers in tandem premises associated with other exchanges which are under the control of this central in tandem. The different types of calls can be studied individually and with appropriate variations.



   Assume again that the considered local tandem exchange is exchange RE, and first consider a call that arrives from a remote exchange such as central RD or RB, via trunk 90, 91 , the ringing pulse from the remote control unit activating the ERL relay which causes the EIR relay to be energized (figure 17).

   On the EIR4 contacts (figure 16), this relay completes a self-interrupted drive circuit for the THM solenoid of the uni-selector. acting as a finder, via the common conductor 92 which is occupied and which will be earthed as long as there is a junction line available with the switchboard of immediately higher rank, while on the contacts EIRl ( figure 18), the EIR relay completes a test circuit for the EK relay via its upper winding as well as the brush and the ETH4 or ETH9 bank, and up to conductor P.

   The junction lines with the main exchange are the only outputs on which the battery is normally connected in the bank P, each battery of this type being connected via a DP relay (figure 13) and a parallel resistor DYE in the input selector.

   Consequently, when one reaches a free junction line, the relay EK comes into action to stop the movement of the switch on the contacts EKl (figure 16) and to energize the relay EKR in series with the electro-.

  <Desc / Clms Page number 66>

 
 EMI66.1
 magnet nJ1lL which, in this case, has no action, D [wl.1 the input selector, the relay DP (figure 13) causes, when it comes into action, the operation of the :: celai:;. DOG and also
 EMI66.2
 the entry into action of the DRF slow relay for la, cra.v.r, rai:

  uio of a ringing pulse in the direction of the outside through the junction conductors 80 and 81, either in the direction of the main exchange as in the example co @ -
 EMI66.3
 w; ": y ', either in the direction of the tandem exchange miva-t, and e' '' 'be this tandem exchange and the main exchange, to which C c1. the maneuvers which vi61 ('. 0: 1 of ' to be described is fulfilled alorv (2.0./ " <'the repeater e "- tar-dem of this last poet.



  1) /. t:;. 1.t;:;. ant in act3on, the relay l # (figure 16) establishes the continuity of the input junction conductors 90 and 91 through the tandem finder and the - trée, and up to the connecting conductors 80 and 81 (figure 14) went to the main exchange, while at the same
 EMI66.4
 temp,: i il;, 'establishes an operating circuit via the brush and the H bank for the DJA relay. (fi &, 1,, 1.1'6 15) in zlraie with the EOG relay (figure 17) which, in this state of: 0.? 4tICtWSeciy''t, exerts no action.



  LI relays ÈRL iftainfient aivzi 10j ;; teml?; J that the ringing is applied from the calling remote exchange, and when this ringing cezi> e, ralai j) recit returns a. its previous position and activates the EIG relay through the intermediary of "contacts EIR5 of the relay: E1E which, at this moment, falls slowly. The link> I of junction 90, 91 by which the call arrives is then extended up to the polarized rectifier relay ED, the direction of the current coming from the central
 EMI66.5
 remote being such that it activates this relay # as long as the AC conductors ;;. versatioa, of the junction line;:, have inverted in the bank of the switches (AJ't) (figure 8) or C ) i'3 (Figure 12).

   The ED relay causes the operation of the LDll relay which, and, coming into action, maintains both: celai ", EIC

  <Desc / Clms Page number 67>

 and EIR, while, on the contacts EDR2 and EDR4 (figure 17), it reverses the potential in the forward direction to achieve the holding conditions for the next step if there is one.



   Different variants can then occur depending on whether the call is intended for a subscriber: a) obtained through the exchange to which the exchange considered is immediately subordinate; b) obtained through an exchange in tandem located between the exchange considered and the one to which the exchange considered is subordinate; c) the exchange in which the repeater is located; d) attached to another remote exchange directly connected to the considered tandem exchange; e) obtained through an exchange in tandem connected to the exchange considered and located, with respect to the exchange to which the exchange considered is subordinate, on the far side and at the same time as the path followed by the call .



   Under no circumstances may the call be intended for a subscriber of the originating exchange, given that such a call would be established automatically by the subscriber and using the local sound link device. central.



   In case a) or b), the communication between the calling party and the called party is carried out by the operator in the manner already described, without causing appreciable changes in the equipment of the figures. 13 to 18. The relays EA (figure 17) and EB (figure 16) are energized when the continuity of the loop is established up to the circuit situated in front, and the operator) the remainder on line. if the call is routed through the exchange to which the exchange considered is subordinate.

   The cut is obtained in either of the two aforementioned cases by the fact that the calling subscriber returns to its previous position, which has the effect that the relays

  <Desc / Clms Page number 68>

   ED and EDR (figure 16), EIR and EIC (figure 17), EK (figure 18) and EKR (figure 16) fall into the tandem repeater in
 EMI68.1
 this order, the relays: D; 1, DOG, DRF and DJA (figure 13) also falling into the input selector by ii1.te of the withdrawal of the earth potential of the conductor P during the fall of the
 EMI68.2
 relays EIR and EIC.



  In case a), if the attendant withdraws the refitting plug, or in case b) if the subscriber fievicïû, his previous position, the BA relay (figure 17) falls in provocative way.
 EMI68.3
 quait the operation of the EC and EGà relays (figure 16). When the EB relay drops, the relay circuit. EIC is cut, which
 EMI68.4
 causes the EIR, EK and UKR relays to drop as before. The opening of the initial loop of entry on the con-
 EMI68.5
 tacts LIC6 causes the drop of> relays ED and E: DH and initiates the cut, in the central finger c1.em, [1J'deur, and the withdrawal of the earth potential of the conductor al of the tandem seeker causes the fall of the active relays in the selector to. 'to 4: C' e.



  Regarding case c), e.g. t-é ± - <5. make a call from an exchange away and destined for a subscriber of the local tandem exchange considers, it will be assumed that the exchange to which
 EMI68.6
 the tandem exchange considered is ëBordered has been reached via another tandem exchange, ie the central RB calls the central RD. When the operator inserts her call card into the multiple junction jack through which the call arrives, an unbalanced tension
 EMI68.7
 .üo {e -'- '":: 1.'1 ée supplied by the battery is automatically branamise- ..1,', - ',:' to the repeater Ci '! tandem which is located at:

  .1 ". The nearest Jill requesting tandem exchange, this reùqt:; ïlibx.,> Ervaflt to excite relays similar to EPC (figure 17) and EPR (figure 16), the relay Eîfic é i, e , t cerzx'i; .- cixcii'tc 'at this time by 1 e CO' '' v; LCtû 1!; OG5. bn entered into action, 1t3 ez, <# 1 1. i El'H a p p 1 1 - that the battery voltage via the resistor

  <Desc / Clms Page number 69>

 Tance EYG (figure 18) on conductor H via the brush and the ETH5 or ETH10 bench and momentarily causes the operation of a relay similar to the DOV relay, and consequently also that of the DOVR relay (figure 13) .



  When the signal constituted by the imbalance ceases, the EPC, EPR, .DOV and DOG relays drop, while the DOVR relay remains actuated, as does the DG relay which came into action when the DOG relay fell, the DOVR relay is maintained by means of a circuit comprising the contacts DG3 and DOVR2 in the operating position and the contacts DHR5 and DPC1 which are in the rest position, this circuit leading to the earthed terminal. Returning to its previous position, the DOG relay again connects the attendant's junction line to the input selector in the RE central unit.



   The first digit selected by the attendant in the input selector of the RE exchange will be the number 8, which corresponds to the RD tandem exchange in question. Therefore, at the end of the pulse train, and as the DJA relay (figure 13) is already actuated, the DOG relay is actuated again to reverse the call back to an additional rung along communication with this RD central.



  The DOG relay also causes the DA, DB, DG and DOVR relays to drop, so that the DOG relay is subsequently maintained through the DOVR2 contacts, while the DOG7 contacts prevent the switch from returning to its normal position. When the DOG relay comes into action again, the operator's loop is extended into the tandem repeater located in the first tandem exchange RE and causes the operation of a relay such as LA (figure 17), after which the relay EB (figure 16) comes into action.

   When activated, the DOG relay also transmits the battery voltage back through

  <Desc / Clms Page number 70>

 of resistor DYF (figure 13) to conductor H during the drop period of the DOVR relay, so that the EOG relay (figure le) is actuated in the tandem repeater of the central RE .

   on contacts EOG3, the DOG relay completes a locking circuit for itself and opens the circuit of the slow relay EIR and, on contacts EOG1 and EOG4 (figure 16), it sends back an earth voltage unbalanced by through the connection of the earth potential which passes through the contacts EOG1, ELR5 and ENR2 and then through the delay winding EI and up to the positive junction line, and also through ENR4 contacts and EMRB rectifier and EOGL and EA2 contacts and up to the negative line. This connection to earth is removed when the EIR relay drops after its delay time has elapsed.

   In the local tandem exchange RD considered, the EPC (figure 17) and EPR (figure 16) relays are then actuated, the latter relay applying the potential of the battery in the forward direction via the EYG resistor (figure 18). ) and up to conductor H, so as to drop the DOG relay and activate the DA, DB, DC, DOVR and DG relays in the input selector of this control unit, and thus ensure the connection of the selector switch. input so that it is ready to receive pulses. The reversal of the DOG2 and DOG3 contacts has the effect of reversing the current flowing in the junction line from the central RD to the central RE, and the ED relay of the latter central then drops and causes the drop of the EDR relay. However, the EIC relay is then maintained through the EOG7 contacts.

   The relay EA of the RD control unit is maintained by the INTERMEDIATE of the loop which includes the DOV4 and DB2 contacts, the DYA resistor and the DG5 contacts.



   The RD central entry selector is then set to the line of the requested subscriber by an additional maneuver

  <Desc / Clms Page number 71>

 'selection, the impositions being repeated by the repeater in tandem of the central RE by means of the relay EA and the operator triggers the bell in the usual way by operating his key to transmit back the unbalanced voltage of the battery. This is used to energize the EPC, EPR and ENC relays in the first tandem exchange RE, the ENC relay being connected to the circuit following the operation of the EOG5 contacts. Then, on the contacts ENR2 and ENR4 (FIG. 16) the unbalanced voltage of the battery is sent back again to the second central tandem RD.

   In this central unit, the junction conductors such as 80 and 81 (figure 13) ensure the connection via the rest contacts of the DOG relay with the DPC and DA relays, therefore, when receiving the part of the first central in tandem in a repeated way the signal constituted by the unbalanced voltage of the battery, the relays CPC (figure 15) and DNC (figure 14) are actuated, while, on the DNCL contacts (figure 15), a The circuit is completed for the DRR relay which ensures the connection of the ringing current,
When the called party answers, the DD relay comes into action to transmit back an inverted voltage which again activates the ED and EDR relays in the tandem repeater of the RE exchange, after which the inversion is repeated. and sent back to the operator.

   In order to link the correspondents together, the key operator then reverses the key again, which again has the effect of transmitting an unbalanced battery voltage, and this maneuver is repeated due to the tandem repeater of the central RE of the usual way. As the DD relay is then actuated again, a local operating circuit is established for the DCR relay, the DP relay

  <Desc / Clms Page number 72>

 (figure 13) having been activated by the requesting tandem repeater.

   The DCR relay operates as already described above to apply the earth potential on the DCR4 contacts (figure 13) on the input conductor SW coming from the tandem switch, while on the DCR3 contacts ( figure 14) it applies a locating voltage through the battery by means of the resistor DYL and the relay DSR as well as the DOG6 contacts on the conductor D of the requested subscriber which is connected to the bank SW (figure 15).

   The potential of the earth applied through the SW conductor (figure 13) in the tandem finder scope causes the ERN relay to operate (figure 18), this relay thus preparing, on the ERN6 contacts, another loop maintenance for the ER relay via the EYF resistor, while, on the ERN2 contacts, it transfers the EK relay to the ETH3 or ETH8 brush which ensures the connection, via its bank, with the conductor SW grounded.

   At this moment, the EK relay drops, as a result of the short-circuiting effect of the earth, and when falling causes the EKR relay to switch (figure 16), thus re-establishing the self-interrupted control circuit of the earth. ETHM electromagnet, but in this case via the ERN8 contacts, since the maneuver must be done even if all the junction lines are occupied. At the same time, the DP and DRF relays (figure 13) of the input selector drop, due to the removal of the earth of the P conductor.

   The brushes of the ETH switch then turn in search of the identification or polarization voltage, by the battery, of the requested subscriber, voltage which will appear in the ETH3 or ETH8 bank which is connected to the SW conductors. , and when this locating voltage has been reached, the EK and EKR relays come into action again and the subscribers are connected to each other by means of a circuit containing the tandem repeater of the central RD only.

   The DSR relay then comes into action and drops the DCR relays and

  <Desc / Clms Page number 73>

   DHR and activates the DCN relay to provide the operator with a conversation circuit and reestablished:!. ' its control commands,
When the attendant notices that the desired conversation has started between the correspondents, she removes her plugs, as a result of which a momentary imbalance of the earth voltage is transmitted to the tandem repeater of the RE exchange to activate the EPC and EPR relays. This maneuver is repeated in the RD control panel as usual, and it also results in the EOG relay in the RE control unit falling, due to the opening of the EPRS contacts.

   When the imbalance ends leaving the loop open, the EA and EB relays drop, the .EG and ECA relays go into action, and the EIC, ED, EDR, EK and EKR relays in turn drop to bring the repeater back into the normal position.



  The fall of the EKR relay causes the DP, DFR and DOG relays to drop in the input selector of the RE control unit, which then returns to its normal position. In the RD control panel input selector, the DPC relay drops the DOVR relay, and then the DA, DB, DCN, DH and DG relays drop, and the switch returns to its normal position. The relay EK (figure 18) continues to be maintained by means of the brushes ETH5 or ETH10, and of the conductor H which is connected to the normal conductor P of the circuit of the line of the called subscriber, while maintaining thus in series with the cut-off relay CO of the requested subscriber (FIG. 4) which, under these conditions, also comes into action.



   When the calling party and called party hang up, the ED, EDR, EIR, EIC, EA, EB, ERN, EK and EKR relays drop one after the other, and all the equipment returns to its normal position.



   In case d), where the called subscriber is attached to another remote exchange directly connected to this exchange in tandem,

  <Desc / Clms Page number 74>

 the operation is very similar to that of case c), except that in case d) the operator selects another tandem repeater serving the desired remote exchange, instead of directly selecting the subscriber. as the level to which the input selector is raised does not correspond in this case to the group of junction lines through which it was put into service, the DJA relay of the level concerned is not actuated, therefore the DAR relay is actuated to initiate a seeker maneuver.

   When an unoccupied trunk line is found, the DHJ and DHR relays are actuated, and the conductors coming from the operator are extended to a tandem repeater similar to the one shown in Figures 16 to 18, and to which access is obtained through the ISm conductors indicated by braces at the top of figure 18. The EA, EB and EOG relays of this device are then actuated, and a loop is disposed across the outgoing junction conductors such than conductors 90 and 91.

   When the attendant selects the number representing the number of the desired correspondent in the terminal exchange, impulses are repeated for this purpose on contacts EA2, and the EC and / ECA relays come into action in the usual way to improve the circuit. impulse by the disconnection of the ED and EI relays, and their subsequent reintroduction in two stages.



  The ringing begins with the attendant reversing her key, which has the effect that the unbalanced battery voltage is applied to the line to operate the EPC, ENC, EPR and ENR relays. The transmission of the unbalanced battery voltage to the front is then recommenced via the contacts ENR2 and ENR4, which causes the operation of the equipment such as that shown in Figures 9 and 10, for the transmission of the battery. warning to the requested correspondent. When the latter responds, the inverted voltage sent back through the

  <Desc / Clms Page number 75>

 The line operator activates the ED relay which causes the EDR relay to operate, and the inversion is repeated in the return transmission, to give the attendant control of the response.



   Under the effect of this maneuver, or when it has the assurance of having reached the desired correspondent, it applies again the imbalance of the battery, following which the potential of the earth is applied by the via contacts EPR6 and ED2 on conductor St, from where it is applied via contacts DHR1 (figure 18) for operating the DCR relay. In the tandem repeater through which the call arrives, the ERN relay is then actuated again from the SW bench by means of the DCR4 contacts and the uni-selector scans its contacts to find the junction line marked through the conductor SW and from the input selector bank.

   The junction line found in this case by the uni-selector working as a finder will not be a junction line which extends to the main exchange for which the scanning is done under the control of the brush P, so the device is- it is arranged so that an earth potential is permanently connected to the associated ----------- P contact, for example the P contact associated with the junction line 90, 91 which extends into the THM Tandem Multiple Finder Finder at the top of Figure 17.

   Therefore, when the EK and EKR relays come into action again in the requesting repeater when the called distant trunk line is found, the EJD relay (figure 18) is actuated through the P brush and the contacts EIC1, ERN1 and EKR5, and this relay removes, on contacts EJD1 and EJD2 (figure 17), the EA and EPC relays from the line.

   Similarly, in the requested repeater, the EJD relay is operated via

  <Desc / Clms Page number 76>

 the lower winding, earthed, of the EK relay, of the ERN5 and EKR4 contacts and of the brush and of the ETH5 or ETR10 bank of the requesting repeater, as well as of the H conductor which enters the requested repeater through the multiple THM (figure 17), and which ensures the connection, via the normal contacts EKR5, with the EJD relay of this repeater.



  However, since the ERN relay is not actuated in the requested repeater, the EA-relay maintains itself in a local circuit comprising the ERN7 contacts and the EYD resistor, and thus maintains the EB and EOG relays. The reason for these maneuvers is that in the considered call going from one trunk line to another, there are two tandem repeaters which are interested and since the two trunk lines are outgoing and request the combination ED and EI relays (Figure 16) both have their EA relays removed from the line to give the minimum transmission loss conditions.

   The calling repeater provides the EQB and EQC conversation capabilities, access to the requested repeater being obtained through the multiple of Fig. 17, as discussed previously.



   When the operator removes the cards, the fall of the equipment which she used in establishing the communication is accomplished as described above, under the action of the Usual momentary application of the unbalanced earth potential, combined with the subsequent opening of the loop. The disconnection of the two-way call through the two tandem repeaters occurs when the calling party hangs up, as a result of which the ED, EDR, EIR, EIC, ERN, EJD, EK and EKR relays of the repeater of the plaintiff fall in their turn. The fall of the ERN relay removes the earth potential of the conductor H, causing the EJD, EA, EB and EOG relays of the requested repeater to drop.



   The case where the call must be made through the

  <Desc / Clms Page number 77>

 diary of a remote tandem exchange attached to the exchange considered and located on the route of the call, that is to say case e), has already been studied in detail. The call is made as in case o) up to the point where the attendant selects the input selector in her exchange. The number selected will be the one which corresponds to the group of trunk lines containing the envisaged repeater, that is to say the one which contains the outgoing call, which has the effect that a new reversal phase is required.

   When moving the input selector forward step by step vertically, this selector causes the operation of the DOG relay (figure 13) by means of the DAW vertical brush in the usual way for a call of the inverted type, following whereby, and as long as the DJA relay has already been actuated under the effect of the outgoing call, the battery potential is applied through the DYF resistor and the DOVR1, DN3, DOG1 and contacts. DJA3 up to wire H to energize the EOG relay (figure 17) in the repeater through which the call arrives. When it comes into action, the EOG relay removes, on the EOG2 contacts (figure 16) the shunt of the pulse repetition contacts EA2, while on the EOG3 contacts (figure 17)

   it disconnects the EIR relay circuit. During the slow drop of this latter relay, an unbalanced earth potential is transmitted back through the junction line 90,91 to the remote tandem exchange, so as to cause the operation of the EPC relays and EPR in the tandem repeater of this central, after which, by applying the voltage of the battery to the conductor H, the EPR relay actuates the DOV relay to pass the line to the input selector of this central to enable it to receive the selection pulses that can be transmitted.



   Then, the tandem repeater of Figures 16 to 18 must transmit, in addition to the pulses, the different ones.

  <Desc / Clms Page number 78>

 control signals which are of two kinds. The first of these signals, ie the unbalanced earth potential, is intended for cutting off the selected part of the call line, and its effect on the selector has already been described. This signal is also used to rotate the repeater back, from its output, from its state corresponding to outgoing communication to the state corresponding to incoming communication, as would be necessary after the exit. execution of a verification call.



  It can be seen that when the EOG relay is actuated, the reception of a signal constituted by the unbalanced earth potential causes the operation of the EPC relay, but not that of the ENC relay, consequently the locking circuit of the EOG relay opens. . When this relay drops, and when, in addition, the imbalance ceases, a circuit is completed via the contacts EPR5, EOG3, EDR3 and EIC5, to activate the EIR relay again, the circuit being thus set. - born again in the state in which it was before the reception of the reversal signal. The other kind of signal is constituted by the series of intervention cuts, which consists of the voltage of the battery applied to the two wires.

   In this case, with the EOG relay actuated, the operation of the EPC relay is followed by that of the ENC relay, the ENR restoration relay having the effect of ensuring that the EOG relay does not drop. The ENR relay is also used to apply the unbalanced battery voltage, as already described, to the next repeater or selector.



   The other main type of call conveyed by this circuit is that of calls that go out to the remote exchange or to the remote exchanges reached via the trunk line 90, 91 (figure 16).



   The following three cases must be considered: 1) Calls established through the exchange

  <Desc / Clms Page number 79>

 to which the exchange considered is subordinate, or through a tandem exchange located between the tandem exchange considered and the exchange to which the latter is subordinate,
2) Calls originating from a subscriber attached to the local tandem exchange.



   3) Calls from another remote exchange dependent on this local tandem exchange.



   In the first of these cases, the repeater is occupied from the selector banks via the. multiple ISM (Figure 18) and the actuated relays are EA, EB and EOG relays. The repeater then operates as an automatic-automatic repeater operating in the forward direction, the pulses received being repeated by the contacts EA2 (figure 16) towards the outside and via the junction line 90, 91.

   Provision is also made for the application of control signals constituted by an unbalanced voltage, via the relays EPC, EPR, ENC and ENR, as has already been described. of
In the second / aforementioned case, that is to say when the call comes from a subscriber attached to the local tandem exchange, the uni-selector which, in the repeater, operates as a seeker has the effect of connect the called subscriber to the calling local subscriber independently of the exchange to which the local tandem exchange is subordinate, and also to cause the forced fall of the local connecting device when communication has been established between the two subscribers.

   In this case, the equipment of figures 13 a.15 is occupied from a local connection device via the access shown at the bottom of figure 13, and when the attendant proceeds to selection, the input selector scans its banks to find a tandem repeater like that of figures 16 to 18 which is associated with a junction line with the desired exchange, whose occupation is made via

  <Desc / Clms Page number 80>

 the ISM access shown at the top of figure 18. The pulses are then repeated to set the input selector in the remote exchange and to bring it to the line of the desired correspondent whose ringing sounds when the attendant reverse his key.



   When the desired correspondent has answered, the operator reverses his key again to apply an unbalanced battery voltage, under the effect of which the EPC, ENC, EPR and ENR relays come into action, while the DCR relay (figure 18) comes into action via the ST conductor. In this case, as the DAR and DSC relays have been activated, the earth potential is applied to the RN conductor to activate the ERN relay (figure 18). This then causes, on the ERN8 contacts, the operation of the searcher in tandem and, on the ERN2 contacts, the establishment of a test circuit for the relay EK up to the bench SW.

   The calling party is identified by means of the battery and by means of the DRS relay and the DYL resistor, as well as the DCR3 and DOG6 contacts, and by means of the local connection device and the conductor D of the subscriber, conductor who is connected to the SW bench of the researcher in tandem.



  During operation of relays EK and EKR, the calling subscriber is connected via contacts EKR1 and EKR3, while on contacts EKR4 the earth potential supplied via a low value resistor is applied via the lower winding of the relay EK to the conductor H of the tandem repeater, this potential being propagated to the conductor P of the subscriber in the local connection device, to bypass the relay d interruption of this device (CFH relay in FIG. 12) and then cut off local communication.



    Then the DP relay (figure 13) also drops due to the opening of the CFR5 contacts (figure 12), which in turn causes the dropping of the DRF and DRC relays.

  <Desc / Clms Page number 81>

 



   When the attendant is sure that the correspondents have been properly connected, she withdraws her call card, following which an unbalanced earth potential is momentarily applied to the line. This has the effect of activating the DPC relay, which causes the DOVR relay to drop in the usual way, while under the effect of the resulting drop of the DG relay the input selector returns to its normal position.



   Communication through the tandem repeater is cut off when the calling party hangs up, as a result of which the EA, EB, ERN, EK, EKR and EOG relays in turn return to their previous position, while the EC relays and ECA are momentarily activated.



   In the third case, which is when the call comes from a subscriber connected to another remote exchange and is intended for the central tamdem in question, the tandem repeater associated with the calling remote exchange is connected to a line li - junction breeze with the main exchange, via the input selector, and in the usual way.

   After inquiring about the desired number, the attendant pushes her call card into the multiple jack of the trunk line through which the call arrives, resulting in a signal being set. by the unbalanced voltage of the battery is transmitted automatically, in the usual way, to actuate the DOV relay and the DOVR relay and then drop the DOG relay, following which the tandem repeater through which the call arrives is maintained , and the attendant obtains access from the input selector. When the desired number indicating the remote exchange has been selected, the input selector scans its contacts, and occupies a tandem repeater associated with a trunk line with the desired remote exchange, or going on. direction of this central,

   this repeater working as a normal automatic-automatic repeater

  <Desc / Clms Page number 82>

 for the rest of the digits which must be selected to reach the desired party. The attendant then transmits the ringing signal by operating her key as usual, the unbalanced battery voltage being repeated by the ENR relay in the requested repeater.



   When the called subscriber answers, the attendant applies again a signal consisting of the unbalanced battery voltage, to ensure the connection of the calling subscriber and the called subscriber via the local tandem exchange. considered. As was explained above, the EPR relay of the requested repeater then applies the earth potential to the ST conductor so as to actuate the DCR relay which, on the DCR4 contacts, applies the potential of the earth on the SW conductor which extends to the multiple TEM (figure 13) of the tandem finder, to ensure the operation of the ERN relay in the tandem repeater by which the call arrives. At the same time,

   the identification potential of the battery is applied via the DYL resistor and the DRS relay (figure 14), the DCR3, DSC6 and DHR6 contacts, the bank and the selector brush ::: Si (figure 15) and the SW conductor (figure 18) which extends to the interior of the multiple THM (figure 17) of the tandem finder, through a connection like that which comes from the multiple ISm of the input selector and which extends to the SW contact in the multiple THM of the tandem finder associated with the called and particular tandem repeater considered.

   During the operation of the ERN relay in the tandem repeater through which the call arrives, the tandem seeker switch of this device is driven in a seeker movement for the search for the locating characteristic by the battery of the driver SW of the called tandem repeater. When the EK and EKR relays of the uni-selector of the tandem repeater which works as a seeker come into action to stop

  <Desc / Clms Page number 83>

 the movement of the switch, the earth potential is applied in the forward direction, through the lower winding of the EK relay, the brush and the ETH5 or ETH10 bench and the H conductor to ensure the operation of the EJD relay in the called tandem repeater.

   At the same time, the permanent earth potential which is applied to the input contact P of this repeater is used to ensure the operation of the relay EJD in the tandem repeater through which the call arrives. The result is that the relays EA of the two repeaters are removed from the line for a purpose which has been described above, and that the conversation is exchanged between the two correspondents.



   The input selector and the junction line with the tandem central are cut when the attendant removes her plugs, following which the usual signal constituted by the unbalanced earth potential is transmitted for the operation of the relay DPC and the fall of the DOVR relay.



   The cut-off of the communication established between the two correspondents by means of the two tandem repeaters is accomplished in the manner which has been described above, when the calling correspondent hangs up.



   CLAIMS.

** ATTENTION ** end of DESC field can contain start of CLMS **.


    

Claims (1)

1. Telephone device or similar device comprising a plurality of searchers having access to the same group of lines, characterized in that the searchers are selected with a view to their use by an assignment device, with step-by-step advancement, in the banks of which each researcher is connected to a group of neighboring contacts, 18 assignment device advancing step by step throughout the duration of a researcher's operation at a rate such that the time it takes him to pass over each group of neighboring contacts is sufficient to complete the <Desc / Clms Page number 84> operation of the searchers, which provides the means, in the event that an erroneous searcher is designated for use by the assignment device, to select another finder and start it up as quickly as possible. 2. Telephone device according to claim 1, characterized in that the equipment of one of the central stations is arranged so as to be put into service under the control of a calling party and to transmit indications to this corre- spondent. audible from the amplitude of its movement, the part of the movement of this equipment which extends to a determined position serving to connect the caller correspondent to an operator who is in another central station. 3. Telephone device according to claim 1 or 2, characterized in that the local calls emanating from a particular central station give rise to the automatic establishment of the communication by a calling party who controls the start and stop of the equipment of the exchange by opening and closing its line circuit, while calls from outside the exchange give rise to the establishment of communication under the control of an operator who is in another exchange with which the calling party is put into communication if the line is kept open for a period of time fixed in advance after the transmission of the first signal. 4. Telephone device according to one of the preceding claims, characterized in that one of the central stations comprises switches of two categories each having access to the subscriber lines, the switches of the subscriber line. one of the categories being arranged so as to function automatically and to start as well as to stop under the control of a calling party by means of the transmission of a characteristic signal over the line, while the <Desc / Clms Page number 85> Switches of the other category are arranged so as to be set by impulses from an operator position in another central station. 5. Automatic switch for use in telephone devices or similar devices according to one of claims 1 to 4, and having access to / a plurality of groups of lines, characterized in that, under the effect of the establishment , in the control circuit of the switch, of a characteristic condition, the brushes are advanced automatically and currents at audible frequency are transmitted through the control circuit in order to identify each group concerned. , while, when the initial conditions are restored in the control circuit, the brushes stop, the subsequent reestablishment of the aforementioned characteristic condition having the effect of advancing the switch brushes again and transmitting currents at audible frequency identifying the individual lines, the reestablishment of the condition having the effect of stopping the brushes in a position in which they are in communication with an individual line. 6. Automatic switch according to claim 5, characterized in that, under the effect of the opening of the control circuit of the switch, the brushes are advanced automatically and an audible indication is transmitted in return and as a function of each group, while, when the control circuit is reclosed, the brushes stop in a position such that subsequent opening of the control circuit causes the switch to advance step by step over the lines of the control circuit. next group, and causes the transmission of an audible indication for each line crossed, the next reclosing of the control circuit having the effect of stopping the brushes in a position in which they are connected to a particular line. <Desc / Clms Page number 86> 7. Telephone device according to one of claims 1 to 4, comprising automatic switches by means of which communications can be established under the control of the requesting subscribers, characterized in that, when a call is initiated, the calling party puts into service a numbered interrupt device and prepares it for operation, while under the effect of the application of a characteristic condition to the line, the switch is put into service and the audible signals indicating the group of lines which it has reached are transmitted back to the calling party, the removal of the characteristic condition serving to stop the switch, while on the subsequent reestablishment of the characteristic condition a new selection maneuver is initiated and audible signals are transmitted in return to indicate each inaividual line crossed, so that the abovementioned condition is removed at the desired instant. allows communication to be established with the desired line. , 8. Telephone device according to claim 1, characterized in that communications are established outside the local exchange under the control of an operator and in which devices are provided with the aid of which the attendant can. check the number of a calling party by setting up a call via another route with the number indicated, characterized in that in the case of a call coming from a PBX group where the calling party gives the number of the first line of the group, the switch of the verification train which has access to the calling party's line is arranged to function as a searcher to ensure connection with the particular line of this calling party in the group which is spotted via a separate broom and bench. <Desc / Clms Page number 87> 9. Telephone device according to one of claims 1 to 4 and 7 or 8, comprising a terminal exchange, a tandem exchange and an operator exchange, characterized in that, when a calling subscriber attached to the central terminal occupies a junction line with the central office in tandem, communication is automatically established from this exchange to that of the operator, while under the action of a maneuver made by the operator a switch which is located in the tandem exchange prepares for selective operation under the control of the attendant and through the input junction line, setting this switch to a position corresponding to the terminal exchange causing the conditions to be restored initials, to allow Empress to perform the selective operation of an entry selector in the terminal exchange via the trunk line. 10. Telephone device according to one of claims 7 to 9, in which all the calls originating from the terminal exchange and from the tandem exchange, but not those originating from the local exchange, are established under the control of the telephone. the operator, characterized in that each junction line between the central stations comprises an input selector associated with its input end remote from the operator's exchange, this selector being normally arranged so as to enter in action under the effect of pulses passing through the trunk line coming from the direction of the operator's central office, the switch control circuit being cut when a calling party is connected to the operator by the in - intermediate of the junction line considered, this control circuit being further arranged so as to be reestablished under the effect of a signaling maneuver provided by the operator, to enable her to operate the input selector in the establishment of the desired communication. <Desc / Clms Page number 88> 11. Telephone device according to one of claims 7 to 10, comprising a tandem exchange serving a plurality of remote exchanges and giving access to an operator position in another exchange from which the establishment of the telephone is controlled. all communications passing through more than one exchange, characterized in that each trunk line from each of the remote exchanges which enters the exchange in tandem terminates in a tandem repeater comprising an unnumbered switch giving access to the attached subscribers at the tandem exchange, at the junction lines with the operator's exchange and at the junction lines with each of the other remote exchanges, the unnumbered switch of a tandem repeater used first to establish, under the 'effect of a call from the associated remote exchange, the continuity of communication up to. Empress, and then being put back into service under the action of a signal sent by the operator to ensure direct connection with a called subscriber in the tandem exchange, or with a trunk line going to another remote exchange to which the called party is attached. 12. Telephone device according to one of claims 7 to 11, comprising a tandem exchange connected between a terminal exchange and an exchange comprising an operator position from which the establishment of communications of more interest. from an exchange and requested both from the tandem exchange and from the terminal exchange, characterized in that the tandem exchange comprises one or more link devices serving for the routing of local calls, a input selector associated with each trunk line with the operator's central office, and a tandem repeater comprising an unnumbered switch associated with each trunk line with the terminal exchange, the device being arranged so that during a call from a subscriber attached to the tandem exchange and intended <Desc / Clms Page number 89> to a subscriber attached to a terminal exchange, the calling party is connected to the operator via a local connection device, while the operator sets the input selector so as to occupy a trunk line connection with the terminal exchange, and that it connects the requested party, via the input selector associated with it in the terminal exchange, the unnumbered switch of the tandem repeater being subsequently controlled so as to perform a scanning maneuver to complete the communication with the calling party independently of the trunk line going to the operator's central office. 13. Device according to claim 1, characterized in that the operation of the allocation device above occupied contacts of a group associated with a researcher, is done by self-interrupt. 14. Switch according to claim 5 or 6, characterized in that under the effect of the movement for selecting a group, the brushes are stopped on the last line of the group which precedes the desired group. 15. Switch according to claim 5 or 6, charac- terized in that the circuit for checking the free state or the busy state of a line is kept open as long as the selection movement is in progress. execution. 16. Switch according to claim 5 or 6, characterized in that if the characteristic condition of the circuit. control is held long enough for the brushes to pass over an entire group, the switch is disconnected. 17. Switch according to claim 5 or 6, characterized in that the bench used for controlling the automatic movement of the switch above a group is subsequently used in order to determine whether it is. or if it is not necessary to complete a counting circuit. <Desc / Clms Page number 90> 18. Switch according to claim b or 6, charac- terized in that under the effect of the brushes of the switch reaching a position fixed in advance, the rest of the movement takes place with the control circuit. control in its normal state, but no tone signals are transmitted. 19. Switch according to claim 5 or 6, characterized in that the scanning of a group of similar lines is carried out at the advancing speed step by step above the individual lines of a group that is being scanned. carried out in the control through the control circuit. 20. Switch according to claim 5 or 6, characterized in that the step-by-step advancement of the brushes is controlled by a relay of the oscillating galvanometric type, operating in combination with a relay of the telephone type. 21. Switch according to claim 20, characterized in that the telephone relay is arranged so as to advance the brushes step by step to the first line of the group, to transmit a tone pulse, to control a self-interrupted circuit for the advancement electromagnet, and to energize the galvanometric relay so as to maintain it in an oscillating movement. 22. Device according to claim 8, characterized in that the switch used for verification is also used for carrying out conversa- tion communications allowing scanning according to the so-called PBX system, while when it is used. for verification, the normal circuit which crimped $ complete the scan according to the so-called PBX system opens and a new circuit is prepared by means of the separate brush. 23. Device according to one of claims 9 to 12, characterized in that the introduction, by the operator, of a call card in a jack of a junction line realizes the momentary connection of one of the central battery poles on the two conversation conductors of the line <Desc / Clms Page number 91> connection, while the removal of the plug causes the momentary connection of the other blade of the battery to the two conversation conductors. 24. Device according to claim 23, characterized in that the equipment which comes into action under the effect of the signals comprises a relay with two windings connected respectively to the two conversation conductors and to the opposite poles of the battery of the device. central, in series with the double winding differential relay, one side of the communication comprising another relay normally short-circuited by a contact of the differential relay, so that the differential relay comes into action under the effect of b-connection of one or the other of the blades of the battery on the conversation conductors, in the operator's position, while the other relay is only actuated by one of these connections . 25. Device according to claim 11 or 12, characterized in that each tandem repeater comprises a Stone type transmission bridge and that when two repeaters are connected in series under the effect of calls exchanged between two. remote central units connected to the same central office in tandem, the intermediate feeder communications of the two repeaters are cut to improve transmission. 26. Device according to claim 11 or 12, characterized in that the operator remains connected to the communication established with a view to exercising surveillance, until she performs a cut-off maneuver. , following which the junction line with the operator's central office is cut. 27. Device according to claim 13, characterized in that the operator is able to operate the input selector to establish a verification call with the calling party, and then to re-establish the initial conditions to allow '' establish the desired communication <Desc / Clms Page number 92> the requesting correspondent.