DE363084C - Circuit arrangement for telephone systems - Google Patents

Description

Circuit arrangement for telephone systems. The invention relates to a circuit arrangement for telephone systems, especially for traffic over Trunk lines.

In such telephone systems it is often desirable to have the circuit set up in such a way that an incoming call via a trunk line either after a subscriber in the same office or via a further trunk line to a Subscriber from another office.

This object is achieved according to the invention in such a way that long-distance lines, which are set up for traffic in two directions and the different Combine offices with each other, in each office in a currency exchange with a pulse transmission device end and have a line section between the offices that of the end sections electrically isolated, but inductively coupled to the same. Here is the at the outgoing end provided selector with current impulse transformer set up so that he current surges from the end section to the isolated intermediate section of the trunk line can transmit, while the device combined from impulse transmitter and selector at the incoming end is set up so that it reacts to power surges from the isolated intermediate section receives, responds and either the call after a Local participant passes on or another similar long-distance line chooses that after leads to another office.

The invention is shown in the drawing. If Figs. 1, 2, 3 and -4 are placed next to each other in sequence, then they illustrate a connection established by a remote cabinet of a handheld remote office after an automatic dialer of a second office.

Fig. I illustrates an officer’s cord circuit.

Figs. 2 and 3 show two voters with impulse transmitters (one for each of the two offices), which are interconnected by a long-distance line X.

Fig. 4 shows a trunk line selector that is set up to automatically search for a free line in a selected line group. The apparatus shown in the figures is built according to the well-known Strowger system. The cord circuit shown in Fig. I: includes a calling device S of known design, which can be operated by an officer in order to automatically establish a call with a calling and called subscriber.

The remote connection device N (Fig. 4) is of the usual type, Keith-Erickson system, and the connection switches are provided with circuits corresponding to the two-line system. The redial M, M 'for long-distance connections according to Fig. 2 and 3 are also the well-known Keith-Erickson devices. However, the star switch and test magnet are omitted, and the circuits are modified so that the switches can operate in the desired manner with a two-line monitoring system. In the line line circuit (strongly drawn lines) the redial M 'is included with the repeater RI. Once the connection from the trunk line X to the local line has been established, the repeater coil RI- is in the circuit in accordance with normal practice. Assuming, however, that the connection is continued via the wraparound connector N to a trunk line leading to switches of another office, then the line circuit circuit includes a repeater in the repeater for that office. If it were not necessary for a particular arrangement, there would be two repetition coils in the connection between the two trunk lines, which would entail unnecessary transmission losses.

Means are now provided in the number repeater IUI (and in the other number repeaters), which means that when the connection is transferred to another trunk line, the connected repeat coil 2. is automatically switched off from the power line. - The above-mentioned features of the automatic switches have been mentioned in advance so that they can be better understood in the further course of the description, where they are discussed in more detail.

. The figures show a number of batteries B1, BI, etc., which supply the switching and speech current. In reality, in practice only one battery is used in each office, the positive pole of which is connected to earth. The only exception to this are the batteries that supply the power for the long-distance switches. In addition to the regular office battery, every office has a special battery or generator that has about twice the voltage of the office battery. These special batteries are labeled B5 (Fig. 2) and B, 8.

After a brief description of the arrangement has been sent in advance, the effect of the same will be explained in more detail: For the sake of clarity, the two offices connected to one another by an exchange line X are hereinafter referred to as Office No. i and No. 2, while the third office, which is via an exchange line can be reached from the second office, should be named with No. 3 .

In order to establish a long long-distance connection, the calling party must Participants get in touch with the so-called admission officer of his office. This can be done in any suitable manner, preferably by an automatic one Switch. The calling participant gives the officer the necessary information z. B. the name and address of the person he wishes to contact, and also his own name and phone number, whereupon he returns to the phone appends. In the meantime, the admissions officer writes the data received on a Card which passes the same on to a long-distance connection operator, their duty it is to make the connection you want.

In the case under consideration, the desired subscriber is in office no. 3, who must be reached through office no.

The long-distance liaison officer now has to convince herself first that the long-distance line X, which leads to office no. 9, is free, which she sees from the non-shining lamp L3. If she is convinced of this, she inserts the call plug of the cord shown in Fig. I into the pawl 11 . This closes the following circuit via the cord sleeve: From the earth connection Gl to the armature 35 and break contact, via the break contact of the armature 34 and the armature, winding 28 of the relay 27, contact springs 33 and 32 of the button K, # plug sleeve, sleeve of the latch JI, Line 102, normally closed contact armature 112, the armature itself, the winding of the relay 113 of the repeater M to the battery B4. The relay 27 in the cord circuit is not energized by the current flowing through the line. Relay 113, meanwhile, is energized and through armature 115 completes a circuit from ground GG which includes the winding of slow acting relay 114 and battery B4.

After the relay 114 is energized by the armature 117, the earth connection is interrupted by the normally closed contact of the armature 116 of the relay 1:13, while the armature 118 and iig close electrical circuits for the "occupied" line L3 and the switch-off relay 104. The first of these circuits has the following course: earth at Gl, armature 118 and its normally open contact, line ioi, "] 3esetzt" lamp L3 to battery B2. Multiple "busy" (c-lamps in the other civil servants' posts , which are parallel to the "busy" lamp L 3 , are also switched on. A quadruple exchange line, which can be viewed as a continuation of long-distance line X, is marked with 140 (Fig. I ) and can lead to multiple contacts in the contact rows of the circumferential remote connector N.

From the drawing it can be seen that a branch of the line ioi leads to the test contact io6 and its multiple connections, whereby the "busy" (c-symbol is given to these test contacts of the trunk line X through the mediation of a ground potential. If you now return to the relay 114, Then you can find the circuit for the switch-off relay 104 as follows: Earth connection at C11, working contact of the armature iig, armature iig, line 105, winding of the switch-off relay io4 to the battery B3 Plug sleeve energized, then a switching control circuit is closed via office no. 2, which for the sake of convenience may be followed in the opposite direction, namely: from battery B, 1 via resistor r, working contact of the armature u6 and the armature itself, further via the winding of the. Relay i2o, windings 122 and 123 to the parallel repositioning coil R via contact springs of relay 124, the par allele-connected wires of the long-distance line X, contact springs 9,33 and? 34 of the relay 224, over their normally closed contacts, over windings?, 2 ?, and 9,23 of the parallel-connected repeater coil RI, winding of the relay: z2o, armature 216 of the relay 213 and over its normally closed contact and via armature 217 of the relay 214 and its normally closed contact to the ground connection G10. After closing the mentioned circuit, the relay i2o of the redial-H and the relay 2? O of the redial MI- are energized. The excitation of the relay i2o has no effect on the operation of the relay 114, since the ground connection G7 is interrupted by the armature i - i of the relay i2o.

The relay 22o of the redial M 'is, however, in effect and closes the following circuit: earth connection Gll, armature 218 and its normally closed contact, armature 237 and its normally open contact, winding 226 to the battery B1; by attracting its armature 254, the relay 27,6 short- circuits the capacitor 255. This effect has no particular influence on the connection now established and can therefore be neglected at the moment.

Another consequence of the excitation of the relay: z26 is the closing of a circuit for the slow-acting release relay 227. The current course is as follows: Ground connection G13, armature 238 and its normally open contact, ', vWindering the relay 227 to the battery Bl. The excitation of the relay 22-7 creates a circuit for the solenoid 23: 2 in the usual way with the intermediary of the armature 241 and also closes a "busy" circuit in the following way: Earth connection G14, armature 240 and its normally open contact, line 2oi, " Bcsetzt «-lampe L4 (Fig. 4) Bowie the associated multiple connections on the remote control board in the office no. 2. A branch of the line 2oi extends over the trunk line 240 to the test contact 2o6 and its multiple connections in the contact rows of the circumferential long-distance connection N and the corresponding ones Associated connectors, where the test contacts of the long-distance line X are energized by an earth potential.

The aforementioned operations have all been carried out by connecting the plug to the JI latch. It should be noted at this point that, while the transmission X are set with reference to the official and the surrounding remote connector in office no. 2, the switch-off relay 204 is not set in motion to the flap 203 off. It follows that if the officer in the office number i wishes them through the Läutetaste KI by hand, a signal of the remote official -. Can give disable generator current via the transmission and send the flap 203rd

However, it was assumed that the subject of the viewing connection is automatically concluded and, if This is done, the remote connection official actuated their call key K3, whereby the intermediary of Kantaktfeder 32, contacted with the contact spring 33 out of contact and connected to the contact spring 36 is, the calling device (number switch) S instead of the relay 27 in the circuit of the relay 113 of the repeater M -will be switched on. At this time, the listening button Klin is in the effective position, whereby the official set P is connected in a bridge via the plug tip and ringing line of the calling end of the cord circuit.

Since the speech circuit is independent of any of the switching circuits and, section by section as soon as it is switched on, is kept free, is a skilled beam tin capable while operating its paging device to determine on the basis of certain characteristic sounds in their listeners that the switchgear is working correctly. This applies in particular to the case that "busy" signals are transmitted from the various switching points to the remote station, provided that all outgoing exchange or trunk connections of the desired group should be busy, as will be explained in more detail below.

Another feature of the cord line circuit is that the call device key K 'when actuated, the plug tip and ringing lines the end of the response of the -cord current loop interrupts. It follows that a participant whose line is in communication with the responder of the cord, prevented from doing so will hear anything that is spoken at the calling end.

With reference to further effects, it should be noted that the first digit of the number to be called is the digit o, because the string of the redial is the row that leads to the lines of the circulating remote connector. Accordingly, the officer will now operate the number sector of the call device S according to the number o and thereby interrupt the circuit of the relay 113 of the redial device M (Fig.: Z) ten times. The relay 113 is de-diagnosed correspondingly frequently by these power interruptions and interrupts the aforementioned monitoring circuit, which includes the relay of the #Vahl repeatersM '. This causes the relay 22o to be de-energized in a corresponding manner z, # once and causes a number of interruptions in the circuit of the relay 226.

With each power interruption, the relay 226 in turn is temporarily de-energized and sends a current impulse from the earth connection G13 over the winding of the slow-acting relay 2-2-8 and over the winding of the solenoid 232 connected in series Adjustment of the wave of the redial M ', bls the contact brushes 245, 246, 2.47, 248 reach the horizontal row of ten contacts.

. The Rülais 228, which is in series with the lifting magnet, is excited and since it works slowly, it keeps its armature attracted during the entire series of shock shocks. During the first upward movement of the shaft, a circuit for the switch-off relay 204 (Fig. 4) is closed, namely from earth connection G15 via contacts 26o, line 2o5, winding of the switch-off relay 204 to battery B10. The action of the switch-off relay triggers the flap 203 in the usual way. With the first upward movement of the shaft, a circuit for the relay: z3o is also closed. The current flow is as follows: Earth connection G14, armature 240 and its working contact, armature -63, its working contact, contact 262 and via the winding of relay 230 to battery B11. When the relay 23o is energized, it locks itself independently of the relay 2, 28 through its armature 264 and, through the armature 265 , prepares a circuit for the rotary magnet: 231, which is kept open by the relay gz8 during the lifting movement of the switch. At this point it should be pointed out that by closing the shaft contact262, the line switching relay243, the lower end of which is connected to earth at G14, is connected in series with the magnet. The connection point 267 has in the meantime been connected to earth in the aforementioned manner, so that the relay 243 is short-circuited and remains ineffective for the time being.

If the slow-acting relay 228 is de-energized at the end of the pulse group, it closes the aforementioned circuit for the rotary magnet at the break contact of its armature, which happens from the earth connection G14 -, the rotary magnet rotates the contact brushes 245, 246, 247 when it is excited, 248 and associates them with the first set of contacts that are in the horizontal row in which they are raised. When the armature stroke ends, the rotary magnet opens the breaker contact 266 and thereby interrupts the blocking circuit of the RelaiS 230. When the power is cut off, the relay 23o interrupts the excitation circuit for the rotary magnet, which consequently attracts its armature, and this then closes the breaker contact 266 again . The effect is now suspended depends on whether or not the first circumferential trunk connector, the ends of which are now connected to the redial brushes, is busy. Assuming that this exchange line is busy, the test contact on which the test brush 247 rests will have ground potential, and this ground potential then ensures that the line switching relay 243 1-short-circuits and the relay 230 is energized again. It should be noted here that the relay 242, which is connected in series with the brush 247, has only a very low resistance, so that the relay: z43 can be effectively short-circuited and works slowly in order to act with the aid of a piece of copper so that it does not respond to instantaneous impulses during the busy trunk test. If the relay 230 is excited in the manner described above via the brush 247, then the excitation circuit of the rotating magnet is closed again, whereby the same effects already described are repeated.

The relay 2.3o acts as a self-interrupter to drive the switch brushes step by step by means of the rotary magnet, as long as the test brush 24-7 touches one of the occupied or grounded test contacts. If a free or ungrounded test contact is reached and the rotary magnet attracts its armature again, then the relay cannot be crr # -gt again. The switching relay: z43, on the other hand, is no longer short-circuited and is immediately energized in series with the - mentioned relay 230. The relay 243 has such a high resistance that the relay 230 remains ineffective. When energized, the switching relay 243 opens the circuit for the lifting magnet 232 through its armature -, 7o and, through the intermediary of its armature 275 , switches the brush 247 from its normal connection to the point 267 and establishes a connection with the earthed line o-oi . At the same time, the connection between the line 2o2 and the winding of the relay 2, 13 is interrupted at its armature 272; the thick lines are extended by its armature 273 and 2.74, the line brushes 245 and 248 as well as the Arrtslinien 3oi and 304 after the connector N (Fig.4), and finally with the help of the relay armature 271 a transfer current --is closed, which closes the line relay 307 of the revolving remote connector N (Fig. 4), with the following current flow taking place: From the earth connection G: 13 to the armature 239, via its working contact, the armature 271 and its working contact, the brush 246 and the associated row of contacts to the line, 302, then on via armature 317 and its normally closed contact as well as the winding of the L, # iting relay 307 to the battery BI-2.

When the mentioned circuit is closed, the relay 307 is energized and, through its armature 326 , closes a circuit for the slow-acting trip relay 3o8. When its armature 329 is attracted, this relay 3o8 prepares a circuit for the lifting magnet 31: 8 in the usual way.

It should be noted here that the trunk line 303, which originates from the test contact 352, is not grounded as usual by the trip relay 3o8. On the other hand, the test contact 352 and its multiple contacts to earth potential or the like are placed over the path which leads from the earth connection G14 through the intermediary of the armature 24o, the relay 27.7, the line 2, oi, the working contact of the armature 275 and the armature itself as well as via the low-resistance winding of relay 242 to brush 2.47.

The remote connector N is thus kept busy for other repeaters. Since the relay 2492, as already mentioned, can only be excited slowly, it is not excited by temporary current surges which originate from other repeaters and flow via the now occupied multiple ends of the trunk line leading to the current long-distance connector N.

The officer is now ready to enter the digits that are required to activate the connector N , whereby a free trunk line that leads to office no. 3 can be selected.

In Fig. 4 the contacts of the first row of one of the circumferential remote connectors are shown, it being assumed that this is the row of contacts in which the trunk lines running to office no. 3 end. As mentioned earlier, each row of contacts can contain more than one group of trunk lines and the first three sets of contacts can therefore accommodate the ends of the trunk lines leading to exchange number i. The next set of contacts is connected to an Aintsleitung, which contains the lines 341, 342, 343, which lead to the jack JI of the office. The next four sets of contacts can accommodate the ends of that group of trunk lines that lead to Office No. 3 . The next set of contacts is in turn connected to the exchange line, which leads to the jack 11 . Other * groups of trunk lines can run out into the remaining rows of contacts in the surrounding connector in a similar way, and the next set of contacts is then always connected in the manner already described.

From the foregoing description it can be seen that, since the trunk lines leading to Office No. 3 end in the first contact row of the circumferential remote connector, and since the first of these trunk lines ends in the fifth contact set of this contact row, the Z 'to be called ffern now the digits i and 5 will be.

The officer in office no. I will now operate her call device according to the number i and thereby bring about a temporary demagnetization of the relay 113 of the repeater in the manner described above. This temporary interruption will result in a current interruption in the monitoring circuit which includes the relay = o of the 'redial M' of office no.? The relay 22o is thereby temporarily de-energized and interrupts the circuit for the relay: z26, which in turn causes a temporary interruption in the circuit of the line relay 3o7 of the rotating remote connector N. The relay 307 is also temporarily de-energized and transmits a current surge, starting from the ground connection G11, to the slow-acting relay 309 and the lifting magnet 318 connected in series with it, the control switch brush 37, o being in its first position. As a result of this current surge, the lifting magnet acts and lifts the switch shaft until the brushes 345, 346, 347, 348 are opposite the first horizontal row of contacts.

The relay 3o9 is excited in series with the solenoid 318 and, with the help of its armature 328 , closes a circuit which takes the following course: From the earth connectionG17 to the winding of the relay 310 and to the winding 316 of the magnet 314 connected in parallel with it at this point in time no influence on the mode of action. The action of the magnet 314, on the other hand, places the control switch brushes 320, 321 in the second position in the usual manner.

The officer can now use her call device for the number 5 and thereby again sends a number of current impulses into the circuit of the relay 113 of the redial repeater M. As already described, these power interruptions are mediated by the relay 2?, O and 226 of the redial repeater M-1 repeatedly until they act on the circuit of the line relay 307 of the rotating selector connector N and cause five demagnetizations of this relay. With each demagnetization, the relay 307 sends a current impulse from the earth connection GI6 to the slow-acting relay 3o9 and the rotary magnet 319 connected in series with it; the control switch brush 32o is in its second position. With these current surges, the rotary magnet operates the brushes 345, 346, 347, 348 until they reach the fifth set of contacts in the first row. The relay 309 is energized in series with the rotary measure, m, etün 319, and since it is slow-acting, it holds its armature during the short current surges in order to close the excitation currents, circuits of the relay 310 and the magnet 0 314. At the end of the impulse group, the relays 309 and 310 and the Magnc-t 34 are de-energized. (It is assumed that the fifth contact set is free.) The magnet which controls the control switch brushes 320 and 321 brings the brushes into their third position.

It is assumed, however, that the fifth contact set is occupied and that the sixth contact set, i.e. H. the second contact set, in which velchem the trunk lines of the No. 3 office end, is vacant. Under these circumstances the test contact of the fifth contact set, with which the brush 347 is now in contact, will have ground potential, and the magnet 314 will be excited via the following circuit: earth connection on the b2setztcn test contact, brush 347, control switch brush ' -21 in the second position and Winding 315 of magnet 314 to battery B13. The magnet 314 is kept excited and its armature 332 is in contact with its working contact. As soon as the relays 309 and 310 are de-energized, a new excitation circuit for the rotary magnet 319 is closed with the following current flow - earth connection Gll, armature 3, -98, its normally closed contact, normally closed contact of anchor 331,> anchor 331, anchor 332, its normally open contact, anchor 334, its normally closed contact, winding of the rotary magnet 319 and the control switch brush 320 in the second position to the battery B14. When closing the above-mentioned circuit loading effect of the rotary magnetic 31g a gradual adjustment of the brushes 345, 346, 347, 348 that engage with the sixth set of contacts in contact. Shortly before the end of its stroke, the drive magnet 319 closes the circuit for the relay 310 with the intermediary of its armature 323 , which when it is excited interrupts the last-described excitation current for the rotary magnet with the intermediation of its armature 331. The rotary magnet therefore releases its armature 323 and interrupts the circuit for the relay 3 10 which, when demagnetized, allows the armature 331 to come to its normally closed contact. The excitation circuit of the rotary magnet is not closed again, because the magnet 314 is already demagnetized, the test contact 4o6 d2s sixth contact set is disconnected from the earth connection and has interrupted the circuit for the rotary magnet at its armature 332. The brush of the remote connector N are now come to rest and are engaged with the sixth contact set having a multi-connection with the leading to the Official no. 3 Fornleitung. The control switch brushes of the remote connector are moved to their third position.

By moving the control switch brush 321 into its third A circuit for a "Bc-sets" lamp is switched on, which indicates that the outgoing trunk is busy while a branch in the circuit is in progress extends to multiple test contacts that are similar to the test contact 4o6 are and lie in the rows of the other circumferential remote connector, where by a The outgoing trunk line is busy at the relevant test contact is held.

By moving the control switch brush 320 into its third position, a circuit is closed which includes the switching relay 312 and the relay: z42 of the redial M-1. The current path is as follows: ground connection G14, anchor 7.40 and its contact, line 2oi, Axbeitskontakt of the armature: Z75, through the armature winding de 's relay 242, switch brush 247, contact set 352, line 303, coil of the relay 312 , Control switch brush 320 in the third position to the battery Bi -1. The relay 312 of the heaped remote connector N and the relay -942 of the redial MI are therefore energized in series.

When the relay 242 is energized, it closes a circuit for the relay 224 with the following current path : earth connection G12, armature 244, its work contact, winding of relay 224 to battery B17. After the relay 224 is energized, its armatures 235 and 236 interrupt the connection at their break contacts and establish a connection with the contact springs 233 and 234, these springs leaving the break contacts concerned. This effect connects the strong lines directly to the repeater coil RI, bypassing the line circuit. Two of the repeater coil windings, namely windings 222 and 223, have been bridged with the line current circuit so that the monitoring circuit, which includes the relay 22o, can be maintained. The delay coil 225 is enclosed in the bridge circuit in order to increase the impedance and thereby avoid excessive transmission losses.

If one now returns to the relay 312 of the connector N and remembers that it was energized in series with the relay 242, then the following phenomena will occur as a result of this excitation: At the normally closed contact of the armature 339 there is a line which leads to the tripping magnet 313 leads, opened ' , in order to prevent the line relay 307 and the tripping magnet 308 from being unlocked. By the connection of its armature 337 and 338 with their make contacts are the incoming lines via a 'choice repeaters, similar to that in the Official no. 3, continued through the intermediary of the line brushes 345 und348, and also is under Vermittlumy of the armature 317, the line 3O2 of the Winding of the line relay 307 interrupted and continued to the line relay of the remote redial repeater.

The said line relay would respond to current pulses, which be sent out by the officer at Office No. i to answer the call on an associated To expand participants.

If all the trunk lines leading to office no. 3 are occupied, the circumferential remote pre-connector N would work as follows: Immediately after the rotation of the connector N takes place in accordance with the transmission of the third digit, the relay 309 is demagnetized and the test relay 311 with the line brushes 345 - and 348 connected in bridge as follows: brushes 345, armature 370 and its normally closed contact, armature 325 and its working contact, armature 327 and its normally closed contact, winding of relay 311, winding of relay 328 and its armature, normally closed contact of armature 371 and its armature to brush 348 During the automatic rotation of the connector brushes after the search for an unoccupied trunk line, the relay 311 is connected in a bridge with the various successive lines. However, since the trunk lines are not bridged with a battery, the relay-3ii is not energized. Assuming, however, that all trunk lines leading to office no. 3 are busy, then the brushes will eventually arrive at the contact set that is connected to trunk line 341, 342, 343. The brushes 345 and 348 then arrive at the opposite pole of the battery B1I via lines 342 and 341 and the windings. of relay 340 in connection. Da-, R (Ja-s 311 is temporarily energized in series with relay 340 and prevents further rotation of the switch by opening the rotating magnet circuit at armature 334. At the same time, relay 311 blocks its own circuit independently of relay 307 and 3o9 at its armature 333 and to the anchors 335 and 336 connecting the seconds kundärwicklung the transformer for the "Busy" -Signalmaschine QI, which is in bridge with the strong lines that i traced back to the office no.. the relay 340 is energized and closes the circuit for lamp L7 , but the officer in office No. 2 usually has no time to answer, because the officer in office No. i will immediately interrupt the connection as soon as Fie receives the "Besetit" signal.

However, should the "busy" signal be received in repeated succession and the officer in Office No. i wishes to determine approximately how long it will take for a line to become free, then she can wait on the line. If the officer in Office No. 2 sees the constant lighting up of the lamp L ', then she can wait by connecting the plug to the handle JI. By inserting the plug, the earth connection is removed from the line .343, as a result of which the test magnet 314 at the connector N is de-energized and the brushes are moved to the third position. The relay 312 is then energized and connects over the strong lines so that the officers can talk to one another.

The officer in office no. I can now return her call device button K3 to the rest position. The next operation is the signaling to the called subscriber, which takes place in the following way: A ringing current source is connected to the strong lines in a bridge when the call button KI is pressed. Due to the inductive effect in the repeater coil R (Fig. 2), the ringing circuit is able to influence the AC relay 3o6, which is connected in a bridge in Office No. 2 with the strong lines of the circulating remote connector N (Fig. 4) . When energized, relay 3o6 closes the following circuit: earth connection Gl 1, working contact of armature P4, armature 324, winding of relay 322 and control switch brush 320 (in third position) to battery B14. Through the action of the relay 322 , the ringing circuit generator G, E, N is connected in bridge with the Leiturgsbürsten 345 and 348, whereby ringing current is sent over the line by inductive action in a recovery coil. A frequency alternating current is sent over the line and activates the appropriately set up bell at the desired point.

After a connection with the desired participant has been achieved, the officer in - Imt 1 N'r. i now continue to contact the subscriber who requested the call. It can do this in any suitable way, but it is advantageous to use automatic switches.

When the conversation is over, both participants hang up their handset. The hanging up of the handset at the calling subscriber station causes the relay 225 to bring the lamp L 'to light on the Scb nurstromkreis, and to inform the officer that the subscribers have ended their conversation. This can e.g. B. can be achieved in that the speech current feed relay, through weleb, # s the calling subscriber is fed by the automatic selector set on his line, not shown, is set up so that it is set up when he is excited, i.e. at the moment when the calling subscriber answers the call of the remote operator, switches on a resistor in the line 5o? .c-t and causes the relay: z5 to switch off the lamp L 'during the call. -Nin, # the end of the conversation, the resistance in the line 502 'is then switched off again by the aforementioned feed relay and the lamp L' is switched on by the excitation of the relay 2.5 .

The lamp L2 in the cord circuit is a means whereby the officer at a remote office can give a signal to the officer on the cord line in Fig. I while the plug is in connection with the latch j1. Suppose z. B. that as a result of a call from the remote office, which is answered by hand by plugging into the jack JI, the officer at the local office has brought about a connection with an automatically connected subscriber via jack J-1 and associated automatic switches; If the called, automatically connected subscriber answers, then the monitoring relay 25 releases an armature and both windings of the decay relay 26 have been connected in series via the cord. The winding 31 has a sufficiently high resistance and a sufficiently large impedance that it does not significantly affect the current transmission. Now automatically connected subscriber hangs his hearing # r after the end of the conversation, the relay 25 is again loaded and makes the lamp LI while the high-impedance winding 31 excluded the relay is chaltet lights.

It is now assumed that the officer of the first office is busy and cannot disconnect the connection immediately, while the officer of the remote office, on the other hand, immediately disconnects the subscriber at the remote end of the trunk line and immediately afterwards a ringing stream to establish a new connection via the in the first office sends not yet separate line to the first officer. The ringing current would then flow through the winding 30 of the bridge relay 26 and this relay would attract its armature and open the short circuit of the winding 29 of the monitoring relay 27 provided with a holding winding. The two windings of the relay 27 is now obtained current so that this relay wird.-Lind excites the lamp, - L2 for bringing illumination and f erner to its upper winding 29 bridging short-circuit without Mitfiilfe of the relay 26 eliminated. Since the resistance of winding 3o of relay 26 is low, so much of the ringing current is consumed by this winding that ringing of the self-connecting subscriber is prevented, despite the fact that the connecting plug is still in the pawl.

The relay 9,6 is kept switched on via the cord circuit when the relay 25 is de-energized, so that this relay and the lamp L2 can act when a bleeding signal or an interrupt signal is given, provided the cord plug is used to connect to an ordinary one Providing guidance instead of an automatic line.

The officer can now interrupt the apparatus, which was put into operation by the calling party by removing the plug with the jack JI out of connection.

The effect of the repatriation of the apparatus will be understandable without the need to ask for details. It is assumed that the various monitoring circuits, which lead from one switch to the next, are opened one after the other according to the removal of the plug from the latch JI, in the same order in which they were made. It should only be mentioned briefly that the remote selection repeater M 'and the remote connector N are returned to their respective rest positions through the intermediary of their tripping magnets 229 and 313 as soon as their respective monitoring relays are demagnetized in the usual manner. If instead of a participant of a third office who is called with the help of the turntable line selector N, which works in the manner already described, only via the second office containing the transmitter group selector M 'via a second trunk line, a participant of the second office, which contains the transmitter group selector M' , are called, then this dialer is set to any other than thizehnti contact series of his - contact field. The lines emanating from this other row of contacts are local connection lines that lead to local group voters, and when selecting such a free local connection line, the selector M 'works similarly to the case where he has a line leading to a free turntable line selector connecting to long-distance lines chooses. After the transmitter group selector M 'has switched through the connection to a free local group selector, it is caused to transmit the dialing currents to the local group selector and the line selector of the second office used for the connection with the subscriber to be called.

In such a case, the test line 303 is connected directly to earth in a known manner by means of the relays of the location selector, whereby the relay 242 is short-circuited and its excitation is prevented. This prevents energization of the relay 224 and the disconnection of the telephony transmitter RI from the voice line.

The location of the second selector Office producing the incoming trunks with the participants of the second office, which might by a particular choice surge line as the line 3O2 leading to the connecting lines with remote DrehleitungswählE.r N can be adjusted. However, it is not always desirable to provide specially configured voters for the incoming long-distance connections to be established with the subscribers of the second office, so that the circuit must be such that the dialing currents sent by the transmitter group selectors M 'to the local dialers of the second office to be set are sent , flow over the line loop, i.e. over the two line cores one behind the other. For this purpose, the current impulse relay 226 of the transformer group selector M 'is provided with a special contact spring pair 254 which, by interrupting a bridge connection connecting the wires of the outgoing line loop, causes the selective current impulses in this loop, so that a special impulse line such as 302 is not necessary.

Claims (2)

PATENT-ANspp, -üciiE: i. Circuit arrangement for telephone systems, characterized in that long-distance lines (X) for traffic in two directions are provided between two offices, which end in each Ainte in a selector with an associated surge transformer device - ## ing (H or MI) and between the Amtern include a section which is isolated from the end sections but inductively coupled to the same, the selector (M) combined with the surge transformer and located at the outgoing end of the trunk line being adapted to transmit surges into the isolated intermediate section of the trunk line while the dialer (M1) located at the incoming end of the trunk is arranged to respond to surges received from the isolated intermediate section, select a local trunk, and then transmit surges onto the local trunk for the purpose of setting additional dialers and forwarding the call. 2. Telephony system according to claim i, characterized in that the located at the ankommcnden end of the trunk line, provided with current impulse transmitter is switched such that he -, - .. d ("r connects with local connection dialers or with such voters, the other after others 3. Telephony system according to claim 2, characterized in that discriminating devices (relay 242) are arranged in the dialers provided with current impulse transmitters, whereby when a connection is made with a dialer who is responsible for forwarding the call to a remote office 4. Telephone system according to claim: z, characterized by such a circuit of the impulse transformer provided with such a circuit that this the current impulses either over the two branches of the loop connected in series or via a third line and earth, depending on the type of voter to which the connection is routed.