US1974164A - Telephone system - Google Patents

Description

Spt. 18, 1934. F. SIMON TELEPHONE SYSTEM 2 Sheets-Sheet 1 Filed July 50, 1952 Inuen or Franz Simcm m Sept; 18, 1934. F. SIMON TELEPHONE SYSTEM Filed July 30, 1932 2 Sheets-Sheet [I'LUETL m" Franz Sim an Patented Sept. 18, 1934 r 1,974,164 TELEPHONE SYSTEM Franz Simon, Berlin-Steglitz, Germany, assignor to Siemens and 'Halske Aktiengesellschaft, Siemensstadt, near Berlin, Germany 1932, Serial No. 627,068,

August 5, 1931 magnet D, battery, earth. The rotary magnet D operates and advances the call finder AS one step. Contact 1811 is opened simultaneously with the energization of the rotary magnet D and cuts off the circuit for said rotary magnet. This restores contact 18d to normal so that the circuit for the rotary magnet D is re-established. The rotary magnet thus with the aid of its contact 18d operates as a self-interrupter until the following circuit has been completed: earth, battery, relay T, contact 315, c-wiper set on the calling subscriber's contact, relay Al, contacts 191.01, 201), earth. Relay A1 is energized in this circuit and at contact 16:11 cuts off the circuit for the rotary magnet D and at contact 210:1 0 closes the following circuit for relay A: earth, contacts 220, 2la1, 12w2, llwl, winding II of relay A, battery, earth. Relay A is thus energized and at contact 23a closes a circuit for relay C as follows: earth, contacts 23a, 2410, relay C, battery, earth. Relay C is energized and at contact 22c opens the circuit for relay A over winding II. Relay A, however, does not yet relapse due to the fact that over contacts 250 and 260 the following locking circuit for it has been closed: earth, battery, winding II of relay A, contacts 25c, 27121, a-wiper of the call finder AS over the calling subscribers line loop, b-wiper of the call finder AS, contacts 28p1, 260, Winding I of relay A, earth, which circuit, after relay Al has been released due to short-circuit at contact 290, causes relay T to be energized in its second stage and consequently cuts off the ringing circuit by opening its contacts 1t and 2t. The opening of contact 525 breaks the circuit for relay V over winding I. Relay V, however, does not relapse clue to the following locking circuit: earth, contact 300, winding 11 of relay V, contact 311), c-wiper of the stepping switch WR in position 0, battery, earth. Relay V closes the following circuit for relay E: earth, contact 321), relay E, battery, earth.

Two parallel connected rotary final selectors are used in the present embodiment and each switch is provided with a plurality of contact groups. Both the final selectors LWl and LW2 are provided with five contact groups each comprising 10 line connected contacts with the result that 100 lines are accessible over the two final selectors LWl and LWZ.

Application July 30,

In Germany 7 Claims.

The invention relates to improvements in telephone systems and has for one of its objects the elimination of the contacts (ofi-normal contacts, rotary off-normal contacts) which are 5 actuated by the switch when it operates and which continue to be actuated until the switch is restored to normal.

I This, according to one feature of the invention, is achieved by maintaining a relay, actuated over one of the wipers of the switch when the latter leaves its normal position, energized independent of the energizing circuit extending over the switch wiper, so that it continues to function until the switch is restored to normal.

The invention is also concerned with a telephone system provided with switches which operate as call finders for one trafic direction andfinal selectors for theother traiiic direction, and a further object of the invention is to simplify in a simple and reliable manner the setting of this type of switch which is provided with a plurality of contact groups, this being achieved by providing auxiliary devices which mark therequired contact groups.

The invention will be better understood from the following description of one method of carrying it into effect which should be taken in conjunction with the accompanying drawings.

The embodiment illustrated represents a private branch exchange system in which the subscriber is able to set up internal connections over the connecting devices AS, LWl and LW2 and may obtain a connection with an exchange line AL after the final selector LW2 has been 5 set to a definite contact.

Setting up a connection within the private branch exchange When the subscriber T with the object of setting up a local connection lifts his receiver, relay T is energized over; earth, contact 1t, subscriber T, contact 273, resistance W, relay T, battery, earth. Relay T is of the two step typeand actuates contacts 3t and it only in the first stage. The calling subscriber is marked by contact 313 at the c-wiper of the call finder AS while contact it closes the following circuit for relay V: earth,

contacts 4t, contacts 5t, 6a, winding I of relay V, b-wiper of the stepping switch WR in posi- Q tion 0, contacts Twl, 8w2, 13w2, rotary magnet D1, battery, earth. Relay V only is energized in this circuit while the rotary magnet D1 in known manner is prevented from operating. Relay V closes a circuit for the rotary magnet D as follows: earth, contacts l5c,'16a1, 17c, 18d, rotary If, therefore, the called subscriber is accessible over a contact of the final selector LWl and connected for example to contact 45 of said final selector, the stepping switch WR has to be set to contact 5. The calling subscriber battery, earth. The

' of the Stepping consequently must transmit five impulses first, which, in known manner, cause relay A to be de-energized a number of times corresponding to the number of line loop breakings and the driving magnet of the stepping switch WR to be operated accordingly over: earth, contacts 300, 331), 34a, driving magnet WR, battery, earth. When the c-wiper of the stepping switch WR leaves its normal position, the circuit extending over winding II of relay V is cut off. Relay V, however, remains energized during the impulse series in the following circuit: earth, contact 300, winding II of relay V, contact 35a, battery, earth. Relay V relapses at the end of the impulse series and opens the circuit for relay E at contact 322). When relay E releases, the following circuit for the rotary magnet D1 of the final selector LWl is closed: earth, battery, rotary magnet D1, contacts 13202, 8102, 71,01, b-wiper of the stepping switch WR in position 1-10, contacts 3632, 37a1, 38c, 39011, 40d2, 41b, earth. The rotary magnet is energized and causes the final selector to advance one step. The following circuit is then closed for relay W 1 over the e-wiper of the final selector LWl: earth, battery, resistance W1, e-wiper of the final selector LWl set to contact 1, winding I of relay W1, earth. Relay W1 is energized and closes its own locking circuit: earth, battery, resistance W1, contact 42201, winding I of relay W1, earth. Relay W1, consequently, is energized after the first actuation of the final selector LWl and throws over its contacts which are only restored to normal when the final selector LWl reaches its original position in a manner to be explained in a later paragraph. By means of the contacts of relay W1 therefore, the contacts may be dispensed with which are directly influenced by the actuation of the switch, that is to say, the socalled oiT normal or rotary off-normal contacts.

Relay W1 opens contact 7201 and closes 9w1 so that the circuit for the rotary magnet D1 is influenced independent of the b-wiper of the stepping switch WR. Contact 39d1 is opened on the first energization of the rotary magnet D1 and this breaks the circuit for said magnet. Contact 39d1 is then' re-closed which causes the circuit for the rotary magnet D1 to be reestablished. The rotary magnet Dl with the aid of contact 39111 thus operates as a self-interrupter until the e-wiper of the final selector LW 1 has reached the contact marked by the a-wiper of the'stepping switch WR. Due to the a-wiper switch WR being set to contact 5 by the first impulse series, the switch wipers of the final selector are continually advanced until the e-wiper of the final selector LWl has reached contact 40 when the following circuit for relay B is closed: earth, contact 300, winding II of relay B, contact 430, a-wiper of the stepping switch WR set to contact 5, e-wiper of the final selector LWl set to contact 40, resistance W1, battery, earth. Relay B at contact 412) opens the circuit for the rotary magnet D1. Furthermore, contact 44b causes a locking cirwit to be completed for relay B as follows: earth, "contacts 300, 44b, winding I of relay B, energization of relay 13 causes a circuit for relay V to be closed over: earth, contact 30c, winding II of relay V, contact 45b, a-wiper of the stepping switch WR set to contact 5, e-wiper of the final selector LWl setto contact 40, resistance W1, battery, earth.

Relay V is energized and at contact 430 cuts off the circuit over winding II of relay B. Relay E also is re-energized over: earth, contact 320, relay E, battery, earth.

The calling subscriber now has to transmit an additional five impulses since he can only reach the required subscriber over the 45th contact of the final selector LWl. These impulses cause the rotary magnet D1 of the final selector LWl :to be actuated over: earth, contacts 306, 46b;

47a, 486, 37111, 3612, 9201, 8202, 13102, rotary magnet D1, battery, earth due to relay A closing its contact 47a in accordance with the occurring line loop breakings. When the e-wiper of the final selector LW 1 leaves contact 40, the circuit for relay V is out 01? but this relay still remains energized during the operation of relay A over: earth, contact 300, winding II of relay V, contact 3511, battery, earth. Relay V does not relapse until the end of the impulse series, when, at contact 320 it opens the circuit for relay E. Relay E, however, remains energized a short period after the release of relay V with the result that if the called subscribers station is idle the following circuit in which relay P is energized is closed: earth, contacts 4%, 500, 51c, windings II and I of relay P, winding I of relay P1, c-wiper of the final selector LWl set to the called subscribers contact, the called subscriber relay T, battery, earth. Relay P at contact 5213 short-circuits winding II and maintains the test circuit independent of contact 516. The closing of contacts 533) and 54p causes the lines to be switched through in the final selector.

Ringing current 'is applied to the called subscriber from the ringing current source of supply over: winding II of relay U, contacts 55a, 5310, a-wiper of the final selector LWl set to the called subscribers contact, the called subscribers station, back over the b-wiperof the final selector LWl, contacts 5420, 28201, 260, winding I of relay A, earth. When the called subscriber answers, relay U is energized in known manner in the ringing pause and by opening contact 24a and closing contact 5614 is placed in the following locking circuit: earth, contacts 23a, 560., winding I of relay U, battery, earth. Relay C, after subsequent testing and energization of relay P is maintained energized'over contact 57p independent of contact 24a. The ringing current-is out off by the opening of contact 5524 whereas the a-lead of the final selector is switched through due to the closing of contact 58a. The speaking connection between the calling and called subscribers is then completed.

Relay A is de-energized when, at the end of the call, the two subscribers replace their receivers. This relaythus relapses and at contact 23a opens the circuit for relay C which in turn opens contact 30c and closes 600 thus transmitting impulses from the relay interrupter RU to the driving magnet WR of the stepping switch WR over: earth, contact 60c, e-wiper cf the stepping switch WR set to contact segment 1-10, driving magnet WR, battery, earth, which im pulses cause the stepping switch WR to be restored to normal. The opening of contact 30c cuts off the circuit for relay B over winding I. This relay releasesand restores its contacts to their original positions whereupon contact 49?) breaks the circuit for relay P which then also restores'its contacts to normal so that a circuit for the rotary magnet D1 is closed over: earth, battery, rotary magnet D1, contacts 13202, 81 112, 9101, 36p, 3701, 38c, 39d1, 40012, 41b. The rotary its a circuit for this rotary magnet D1 bymeans of its contact 39d1 operates as a self-interrupter and. causes the switch wipers of the final selector LWl to advance until the e-wiper of said final selector hasxreached its normal position and consequently connected up a differential winding of relay W1 over: earth, battery, resistance W1, e-wiper in normal position; contact 61101, winding 11 of relay W1,.earth, with the result that the contacts of relay W1 are restored to normal, which cuts oh? the circuit for the rotary magnet D1 at contact Qwl. All the various switching means in the system are then restored to their original positions.

If the required subscriber should be connected to, for example, contact of the final selector LW2, the calling subscriber has first to send out 8 impulses and thus cause the stepping switch WR to be set to contact 8. The switching operations as far as the setting of the stepping switch WE are concerned are the same as those already described. When the stepping switch WR however, during its advance to contact 8 reaches contact 6, relay W2 will be energized over: earth, battery, resistance W1, d-wiper of the stepping switch WR set to contact 6, winding I of relay W2, earth. Relay W2 closes its contact 591,02 thus completing its own locking circuit as follows: earth, resistance W1, contact 59102, winding 1 of relay W2, earth. Relay W2 opens contacts 8102 and 131.02 and closes contacts 10102 and 14102. Firstly a switching over from the rotary magnet D1 to D2 is then carried out and secondly the circuit for the rotary magnet D2 is closed independent of the b-wiper of the stepping switch WR.

After the stepping switch WR has finally been set to contact 8, relays V and E relapse in the manner described previously and the rotary magnet D2 is connected up over: earth, battery, rotary magnet D2, contacts 14102, 1Qw2, 36p, 3'7al, 38c, 39d1, 40012, 4121, earth and advances the switch wipers of the final selector LW2 one step. When the rotary magnet D2 operates, however, contact @0612 is opened and cuts off the magnet so that it is deenergized and restores contact 4M2 to normal which then re-energizes the rotary magnet D2. The rotary magnet D2 thereiore'i'n the present case, with the aid of contact 4M2, operates as a self-interrupter. When the final selector LW2 has been set to contact 70, a circuit for relay B is completed in the manner previously described. Relay B at contact 41b opens the circuit for the rotary magnet. Additional impulses transmitted .by the calling subscriber cause the rotary magnet D2 to operate over: earth, contacts c, 46b, 47c, L86, 37111, 36p, 10102, 14102, rotary magnet D2, battery, earth. The final selector is advanced an additional five steps with the result that the switch wipers of the final selector LW2 are set to the required contact which is connected to the 25th contact. The further switching operations are exactly the same as those previously described in conjunction with the setting of the final selector LWl.

The release of the final selector LW2 at the end of the call is carried out in the following manner: Relay A is de-energized when the two subscribers replace their respective receivers. This relay then cuts off the circuits for relays C and U at its contact 28a. Due to the release of relay C the driving magnet WR of the stepping switch WR receives impulses over: earth, contact 600, relay interrupter RU, cwiper of the stepping switch WR set to contact segment 1-10,- driving ma'gnet'WR, battery, earth. The driving magnet is caused to operate until the stepping switch has been restored to normal when the above-mentioned circuit for the driving magnet is out off. The release of relay C with the consequent opening of contact 30c breaks the locking circuit for relay B. The relapse of relay B causes the circuitior relay 1 to be cut off at contact 49%: with the result that the contacts of relay P are restored to normal. The following circuit for the rotary magnet D2 is then closed: earth, battery, rotary magnet D2, contacts 14102, 101.02, 36p, B'Icl, 38c, 39d1, d2, llb, earth. The rotary magnet with the aid of its Contact 4M2 operates as'a self interrupter and advances the switch wipers of the final selector LW2 until it reaches its normal position in which a difierential winding of relay W2 is connected up over: earth, battery, resistance W1, e-wiper in normal position (contact 50), contact 62102, contact 1300, winding II relay W2, earth which causes the contacts of relay W2 to be restored to normal so that the circuit for the rotary magnet is cut oil at contact 10202. The final selectors LWl and LW2, therefore, may only be seized for a fresh call after contact 3102 has been restored to normal due to the fact that they are accessible over said contact 8w2 only.

Relays W1 and W2 thus, by means oftheir contacts replace the ordinarily provided oil normal contacts operated as soon as the switches L'Wl or LW2 advance out of their original position. Contacts Bwl. and 10202 consequently make it possible to operate the rotary magnets D1 or D2 independent of the stepping switch WR. Contacts 'lwl and 8102, as long as thefinal selectors LWl or LW2 have not reached their normal position, prevent a fresh seizure of said final selectors. Furthermore, relay W2 determines which rotary magnet is to be operated according to the transmission of the first impulse series.

Setting up an exchange connection For the setting up of an exchange connection from a private branch exchange the final selector LW2 has to be set to contact 01, that is to say, the calling subscriber must first dial the digit 0 and thus cause the stepping switch WR I to be advanced in'the manner previously described. The transmission or" 10 impulses causes the stepping switch WR to be set to contact 10 and the final selector LW2 is caused to advance until its e-wiper has reached contact 90, in l other words, the switch wipers of the final se lector LW2 must pass over four groups comprising 10 contacts each before they reach contact 90. The switching operations performed for the setting of the call finder and the LW2 are exactly the same as those described in conjunction with the setting up of an internal connection. When the final selector LW2 has been set to contact 01, the following circuit is closed: earth, contacts 49b, 56c, 51c, winding II and I of relay P, winding I of relay P1, c-wiper of the final selector LW2 set to contact 01, relay An, battery, earth. Relay An only is ene gized in this circuit. Relay An closes its contacts 63cm cuit is prepared at contact 63cm: d-wiper of the call finder AS and d-wiper of the switch AW. Due to the actuation of contact Gian relay R is energized over: earth, contacts 640m, 6501, 66b1, winding I of relay R, battery, earth. Relay R final selector and Stan. The following test cir- 1 fit closes its contact 671 which causes the rotary magnet D3 of the switch AW to be energized over: earth, relay interrupter RUl, contact 6861, d-wiper of the stepping switch WRl set to contact 0, contact 671", rotary magnet D3, battery, earth. The rotary magnet D3 continues to ad- Vance until the d-wiper has reached the contact marked over the cZ-wiper of the final selector LW2 and the d-wiper of the call finder AS at contactcl of the switch AW whereupon the following test circuit is closed: earth, battery, resistance W2, contact 63cm, d-wiper of the final selector LW2 in position 01, winding II of relay Pl, d-wiper set to the calling subscribers contact, cZ-wiper of the switch AW, contact 681', winding III of relay Cl, winding II of relay R, earth. Relay C1 is first energized in this circuit and at contact 68c1 cuts off the circuit for the rotary magnet D3. The opening of contact 6501 prevents another subscriber from seizing the exchange line AL.

In addition, relay P1 is energized over the d-wiper of the switch AW and the cZ-wiper of the call finder AS. Relay P1 closes its contact 69101, thus causing relay U to be energized over: earth, contacts 23a, 69121, winding I of relay U, battery, earth. Relay U at contact 2414 cuts oiT the circuit for relay C whereupon the stepping switch WR and the final selector LW2 are restored to normal in the manner previously described. All the switching means associated with the call finder AS and the final selector LW2 are then restored to normal. When relay C consequently releases and opens contact 290, a locking circuit for relays C1 and T is closed over: earth, contact 7001, winding I of relay C1, the c-wiper set to the calling subscribers contact, line 71, relay T, battery, earth.

The switching-through operation is carried out by relay C1 at contact 7201 and 7301 so that relay S can be energized over: earth, battery, contact 74h, windings III and I of relay S, contact 7201, a-wiper set to the calling subscribers contact, line 75 over the subscribers station T, line 76, b-wiper of the switch AW set to the calling subscribers contact, contact 7301, winding II of relay S, earth. Relay S causes relay B1 to operate over: earth, contacts 77S, 78A, relay B1, resistance W3, battery, earth. Relay Bl closes contact 80191 which closes the following circuit for relay V1: earth, contacts 8101, 80b1, relay V1, battery, earth.

The subscriber is now connected to the exchange line and in a position to cause the setting of the appropriate devices in the exchange in any known manner. When, at the end of the conversation, the subscriber T replaces his receiver, relay S relapses. It then opens contact 773 and'closes 79s, causing relay B1 to be shortcircuited. Prior to relay B1 restoring its contacts to normal, however, winding I of relay C1 is short-circuited over: earth, contacts 82121, 83b1, 84s. Relay C1 releases and restores its contacts to normal. When relay B1 now relapses, the circuit for relay V1 will be cut ofi at contact 80271. Due to the release of relay C1 and subsequent opening of contact 7001, the calling subscribers relay T also is de-energized so that it restores its contacts to normal. All the switching means actuated for this connection have then been restored to their original positions.

As will be appreciated from the aforesaid the switch AW in outgoing connections operates as a call finder. If, on the other hand an incoming call arrives over the exchange line AL, the operator receiving the exchange call causes the switch AW to be set by means of impulses in the following manner: The ringing current from the exchange energizes relay A2 in known manner so that a circuit for the signal lamp L is completed over: earth, battery, contact 85a2, lamp L, earth. At the same time the following circuit is closed for relay H: contacts 85Ct2, 86A, 87b1, relay H, earth. Relay H closes its contact 88h and is thus placed in the following locking circuit: earth, battery contacts 89s, 88h, relay I-I, earth. The operator then throws over her enquiry key the contacts of which are all denoted by A so that when contacts 92A and 93A have been closed, the operators set is connected to the exchange line AL. The throwing over of the enquiry key causes contact 78A to open and 94A to close causing the following'energizing circuitto be completed for relay B1: earth, contact 94A, relay Bl, resistance W3, battery, earth. Relay Bl closes its contact 95121 and is thus placed in a locking circuit independent of the enquiry key. The opening of contact 66b1, in addition, prevents the exchange line from being seized by another substation subscriber.

The operator now enquires the number required by the calling'exchange subscriber and after having received it throws over a key, the contacts of which are all denoted by R. This causes relay V2 to be energized over: earth, contact 96R, c-wiper of the stepping switch WRl in zero position, winding I of relay V2, battery, earth. Relay V2 at contact 97122 prepares a circuit for relay E1.

It will now be assumed that the required exchange subscriber is connected to for example contact 45 of the switch AW. The operator then has to transmit five impulses and thus cause the switch WRl to be set'to the fifth contact in the following way. The operators impulse sender causes contact 88276 to be actuated so that the driving magnet WRl operates over winding I in the following circuit: earth, battery, winding I of the driving magnet WRl of the stepping switch WRl, contacts 99f, 100R, 8827c, earth. The driving magnet WRl receives five impulses and consequently sets its wipers to contact 5. As soon as the stepping switch WRl leaves its normal position, relay E1 is energized over: earth, contact 96R, c-wiper of the stepping switch WR set to the contact segment 1-l0, contact 9702, relay El, battery, earth due to the fact that after the stepping switch WRl has left its zero position relay V2 also remains energized over: earth, contact 96R, c-wiper of the stepping switch WRl set to the contact segment 1-10 while impulses are applied to the driving magnet WRl and contact 101wr1 consequently is closed in accordance with its actuation. Due to its slow action relay V2 does not follow the interruptions set up by contact lolwrl. the first impulse series and consequently causes relay El also to releasedue to the opening of contact 9702. Duringthe actuation of contact lolwrl and the energization of relay E1, relay E1 and, over contact 102e1 of the switch AW are disposed in parallel with winding I of relay V2. The rotary magnet D3 cannot operate when placed in parallel with relays V2 and E1. When, however, relay El releases, contact 102el is opened and 103e closed.

Relay V2 relapses at the end of .1

the rotary magnet D3 earth, battery,

Iimpulses which the operator ".Zoff over winding 11.

This completes. the following circuit for the rotary magnet D3 of the switch AW: earth, relay interrupter RUl, contact 6801, d-wiper of the stepping switch WRI set to contact segment 1-10, contacts 104B, 105 103e1, rotary magnet D3, battery, earth. The rotary magnet now receives impulses until the e-wiper of the eX- change switch reaches contact 40 whereupon the following circuit is established: earth, battery, resistance We, c-wiper of the switch AW set to contact 40, a-wiper of the stepping switch WRl set to contact 5, contact 106122 winding I of relay F, b-wiper of the stepping switch WRI set to contact segment 1-49, contact 167R, earth- When the .e-wiper of the switch AW leaves its normal. position and reaches contact 1, relay W3 is energized over: earth, battery, resistanoe W4, e-wiper of the switch AW set to position 1 and 2, winding I of relay W3, earth. Relay W3 closes its contact 1081113, thus completing the following locking circuit in which it is placed: earth, battery, resistance W 1, contact 108w3, winding I of relay W3, earth. Relay W3 in this manner replaces the cit-normal or rotary ofi-normal contacts of a switch since this relay, as explained above, functions on the first rotary step of the switch AW and by means of a differential winding does not restore its contacts to normal until the said switch reaches its original position. A signal lamp L1 is connected up parallel to contact 19602 and relay F and this lamp indicates to the operator when she may cornmence to transmit the second impulse series. Relay F, however, first opens contact 105 which breaks the circuit for the rotary magnet D3.

F remains energized over: earth, contacts 1091.03, 110), winding II of relay F, battery, earth. Relay It causes relay V2 to respond over winding 11 since the ollowing circuit is completed: earth, battery, resistance we, e-wiper of the switch AW set to contact as, a-wiper of the stepping switch WEI in position 5, contact 111 winding II of relay V2, b-wiper of the stepping switch WRl set to position 1-10, contact 107R, earth. Relay V2 is energized and at contact 106122 cuts off the energizing circuit for relay F over winding I. Relay V2 causes relay E1 to be energized over contact 97222, with the result that the rotary magnet D3 is now operated by the additional transmits over the impulse contact 88ik: over: earth, contacts 8817c, 1003, 112;, 10261, rotary magnet D3, battery, earth. When the e-wiper oi the switch AW leaves contact 40, the circuit for relay V2 is out This relay, however, remains energized over winding I parallel to the rotary magnet D3 while the operator transmits impulses. Relay V2 relapses at the end of the impulse series and by opening contact 197222 causes the release of relay E1. Before relay El restores its contacts to normal however, a circuit for relay C1 is closed after relay V2 has released as follows: earth, contacts 113e1, 114122, windings II and I of relay ,.1C1, wiper 0 set to the required subscribers T- relay, battery, earth. Relay C1 completes its own locking circuit over contact 7001 independent of its winding II and contacts 11402 and 11361 which, at the same time, causes the called subscriber to be guarded in known manner. The exchange line is switched through at contacts 72c1 and 7301 and the required subscriber is rung from the ringing current source of supply over: contact 11571., winding I of relay S, contact .i72c1, a-wiper of the switch AW set to the required subscriber, back over the called subscribers station, b-wiper of the switch AW, contact 7301, winding II of relay S, earth. When the called subscriber answers, relay S is energized in a ringing pause in known manner and at contact 89s cuts oil the circuit for relay I-I so that the ringing current is cutoff due to the opening of contact 115%. The operator, by means of her speaking set is connected to the called su: scriber over contacts 116R and 1173 and can now inform him that he is required for an exchange call. She then throws over the keys A and R. and the calling exchange subscriber is then in direct communication with the required substation subscriber.

When the conversation is ended and the substation subscriber replaces. his receiver, relay S releases. By opening its contact 77s and closing 79s relay S causes relay B1 to be, shortcircuited. Relay B1 restores its contacts to normal after its winding I has been short oircuited and by contacts 8201, 83M and 848 also restores relay C1. The release of relay C1 de-energizes relay V1 due to the opening of contact 8101. Winding II of the driving magnet WRl is energized over contact 68c1 in the following circuit: earth, relay interrupter Bill, Contact 6801, d-wiper oi the stepping switch WRI in position 1-1D, contact 1138., winding II 01 the driving magnet WEI, battery, earth. The stepping switch WRI continues to operate until it reaches its normal position. When this occurs, the rotary magnet D3 receives impulses over: earth, relay interrupter RUl, contact 68c1, dwiper oi the stepping switch WEI in zero position, contact 1192123, rotary magnet D3, battery, earth. The rotary magnet D3 operates continually until the e-wiper oi the switch AW reaches its zero position and in this position has caused a differential winding of relay W3 to be connected up over: earth, battery, resistance W4, e-wiper 01"" the switch AW in position 0, contact 1201/03, winding II of relay W3, earth, whereupon relay W3 restores its contacts to normal. The release of relays C1 and B1 causes the circuit for relay V1 to be out off and all the switching means in the systemare then restored to their original positions.

What I claim as new and desire to secure by Letters Patent is:

1. Circuit arrangement for automatic telephone systems provided with a plurality of parallel connected switches or sets of switch wipers characterized in that when a switch or set of switch wipers to be operated is identified a relay is energized which then causes the switching-over required for the setting of the switch or set of switch wipers to be carried out and is maintained energized independent of the setting of the switch until said switch is restored to normal.

2. In an automatic telephone system a movable switch wiper, means for moving said wiper, a relay, a circuit for said relay closed by the wiper when it leaves its normal position, and means for maintaining said relay energized independent of said switch wiper until the switch wiper is restored to normal.

3. In an automatic telephone system a movable switch wiper, means for moving said wiper, a relay, a circuit for said relay closed by the wiper when it leaves its normal position, said relay having a differential winding, and a circuit for energizing said winding when the switch returns to normal to release said relay.

4. In an automatic telephone system a plurality of sets of wipers connected in parallel, means for operating said wipers, means for selecting a set of said wipers for use, a relay energized when the selection is completed, means controlled by said relay for controlling the operating means of the wipers, said relay maintained energized independent of the setting of the switch wipers until the said wipers are returned to normal.

5. In an automatic telephone system, an automatic switch, means for operating said switch to automatically select calling lines and in another instance to operate the switch directively to seize a called line, a marking device in the switch, and means for operating said device to mark the desired group of lines to be selected in either type of connection before such selection is performed.

6. In an automatic telephone system, a trunk operating said switch in response to a call over said trunk to operate the switch as a final selector to seize'a called one of said lines, and a marking switch operated in each type of connection to mark the group of lines to be selected before such selection is performed.

'7. In an automatic telephone system, a combined line finder and connector switch having an operating magnet operated when the switch is used as both a connector and a finder switch to select a calling or a called line, and an auxiliary marking device for determining the group of contacts to be selected.

FRANZ SIMON.

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