US1813175A - Automatic telephone system - Google Patents

Description

July 7, 1931. M. LANGER AUTOMATIC TELEPHONE SYSTEM Filed Aug. 5. 1929 2 Sheets-Shet 1 v 11'11.rEnIur'-- max Le -1521" July 7, 1931. M. LANGER AUTOMATIC TELEPHONE SYSTEM 2 Shets-Sheet 2 Filed Aug. 5. 1929 Patented July 7, 1931 UNITEDSS'TATE'S' PATENT OFFICE max LARGER, or BERLIN, GERMANY, ASSIGNOR '10 sIEmENs & HALSKE Annm- ,ensnnnscnarr, or srmmnssran'r, NEAR BERLIN, GERMANY .avmmurrc 'rnnnrfionn' svsrnn Application flledAuguat 5, 1929, Serial no.

The present invention relates to a circuit arrangement for telephone systems, in which one lead of a subscribers line is used for -special-purposes (signal repeating, feeding from the main exchange battery two .subscribers of aP. B. X.)

The object of the invention is to 'control,

in a particularly simple and reliable manner, the connecting devices of the exchange. by means of the circuit changes brought about by the subscribers stations for settlng up"or completing a connection. This is achieved in that a switching means is brought into action over one lead of the subscribers line by circuit changes brought'about by the subscribersstations for setting upor completing "a connection, and the said switching means 1 controls the switching devices at the connectthe second lead that is not used for the particular purposes.

L In the drawings are shown several methods of carrying out the invention. Thus, Fig. 1 shows an arrangement for telephone systems with call seekers, group selectors, and final selectors, in which subscribers stations N1 and N2 communicating with one another are .fed from the main exchange battery over: I earth, battery, choking coil D4, lead 6, choking coil D6, and thence onthe one hand over choking coil D7, "subscribers loop ,for N1, choking coil D8 to earth, andon the other hand over choke -coil D9,'subscribers loop for N2, chokin coil D10 to earth. I

group selectors, and final selectors, in which over one lead of-the subscribers line for N3 are transmitted the signals for any particular purpose (alarm signal). g

Fi 3 shows another arrangement 6f. the switciing means which is brought into action over one lead of the subscribers 'line and effects certain switching operations over the other le'ad,-and in ths case only the discom v the subscribers station answers an incoming call.

The: rectanglesenclosin the of various relays shown on e drawings mdiw cats that these-relays;, are' made slowracting ing devices of the exchange over the part of.

Fig. 2 s ows a system with preselectors .nection of ringing current is effected when 383,522, and in Germany September 8, 1928.

by the addition of a copper slug on the coreof the relay or in any other well-known manner. If the main station N of a private branch exchan e shown in Fig. 1 wishes to set up a 5 connection with some subscriber of the main exchan e; and for that purpose takes down his receiver, the relay A is energized over one lead, namely lead a in this case, in the following circuit: earth, chokin coil D2, subscribco er s loop of the main station N, lead a, relay A, contact 1t, resistance W2, battery, earth. The closing of contact 2a causes the starting impulse given over the lead ato be transmitted over the lead 6, relay T being energized over: earth, battery, choking coil D5, contact 2a, contact 3t, winding I of relay T, earth. The energizing of winding .1 of T only causes the contacts 4t and.5t to be closed. Contact 4t establishes'the following circuit for relay 7o R earth, contacts 4t, 6t, relay R, battery, earth. Over contact 61' the rotary magnet DM receives impulses over: earth, relay interrupter RU, contacts 61', 7 p, rotary, magnet DM', batter I earth. Hence, the wipers of the call see er AS are moved on until they reach. the calling subscribers line, whereupon the followingcircuit is established over the wiper c1 of the call seeker AS: earth, contact 8r, windings II and I of relay P, wi r 01 of the call seeker AS, contact 5t, winding II of relay T, battery, earth. In this circuit is energized the relay P and the current flowing over the winding II of relay T causes the contacts 1t, 3t, and 6t to be 0 ened, By opening the contact 7;), the relay arrests the rotary magnet DM. At the contacts 10;) and 126p the line is switched through and the impulse relay A1 is enerlgizedoverwindin I in the circuit: earth, c okin g coil D2, s'u scribers loop of the main station N, lead a, relay A, wiper al of the call seeker AS, contact 126 winding I of relay A1, battery, earth whi e winding II of relay A1 is-energize over: earth, .winding1 II of relay A1 contact 10p, ;wiper 61 of t e call seeker A contact 2a, 7

choke coil D5, battery, earth.

v Contact 11;) estabhshes the following circuit: earth ofi-normal contact 1270, I.of relay 6, contact 11p,,battery,,.earth. Ren iii lay C is operated and locks itself over both its windings and contact 130 as soon as the oil'- normal contact 1270 is opened at the first lifting step of the group selector. The short circuit is removed from relay C by contact 14a1, because, as previously mentioned, the relay Al was energized after the call seeker had been positioned on the subscribers line. The positioning of another call seeker on the subscribers line is prevented by the removal of winding II of the relay P from the circuit of relays P and T. There is now the following circuit for the relays P and T: earth, contacts 9;), 1250, winding I of relay P, wiper c1 of the call seeker AS, contact 5t, winding II of relay T, battery, earth.

hen the subscriber N transmits the first impulse train, the relay A1 is released in accordance with the interruptions at the impulse sender, the current being directly withdrawn from the winding I of relay A1 at the impulsesender, while that from winding II of relay A1 is withdrawn by contact 2a at each impulse, because the relay A, which lies in the circuit of winding I of relayAl is also released at each' impulse. In accordance with the impulse train, the lifting magnet HM receives impulses over: earth. contacts 15001,

'160, shaft. contact 1710, winding I of relay.

V, lifting magnet HM, battery, earth. The wipers of the group selector GW are raised to the corresponding level. During this impulse train the relay V remains energized because its windings II and III are short-circuited, making the relay slow-to-release'. .It falls back atthe end of the impulse train and by closing the contact 1811 the rotary magnet DM1 of the group selector GIV receives current over: earth, contact 19791, contact 18o, off-normal contact 2070, rotary magnet DMI, battery, earth; The wipers of-the group selector take one rotary step and shaft contact 1710 is opened. The contact 21dm1 is closed when the rotary magnetDMl is energized; hence, relay V is again energized over: earth, contact 21dm 1, windings II and I of relay V, lifting magnet HM, battery, earth. The lifting magnet is not energized in this circuit owing to the resistance of the relay V. Relay V opens its contact 182;, so that the circuit of the rotary magnet DMl is opened and thus the contact 21dm1 is also openedi Relay V is again de-energized, so that the contact 1812 is closed and the rotary magnet DMl is again operated over the before-mentioned circuit and it moves on one step further the wipers of the group selector GVV. This inter-action between the relay V and rotary magnet continues until the group selector has found a free final selector LIV, whereupon the relays P1 and C1 are energized over: earth, contacts 220, 23a1, windings II and I of re ay P1, wiper c2 of the group' selector GIV, shaft contact 24w, winding II of relay C1, battery, earth. The opening of contact 19 01 interrupts the circuit of the rotary magnet DM1, so that it cannot be energized again. The winding II of relay P1 is short circuited by theclosing of contact 25121, hence no other group selector can set itself onto the seized final selector LW. The

relay V is deenergized when the group selector has been set onto the final selector. The line is switched through to the switch LW over the back contacts 262) and 27 0 and the front contacts 28391 and 29201.

When the group selector GVV has tested, the relay C1 is energized as already mentioned and closes contact 3101. The relay C1 locks itself over both its windings as soon as thefinal selectors LW has opened shaft contact 24w.

lVhen the subscriber transmits a further train of impulses, the relay A1 of the group selector GVV is released in accordance with the interruptions at the subscribers station in the manner already described, and relay A2 of the final selector is energized by con tact 33rd over: earth, contacts 320, 33661, 29 21, wiper a2 of the group selector GI/V, windings I and II of relay A2, battery, earth. V at the group selector GIV are not affected by the release of the relay A1, which closes the contact 15a1, because the lifting magnet HM is connected in series with the three windings of relay V, the proportions being such that they cannot thus be operated.

The energizing of relay A2 at the final selector LIV causes the lifting magnet HM1 and the relay V1 to receive current over: earth, contact 3M2, winding I of relay V1, contact 3514, shaft contact 36w, lifting magnet HMI, battery, earth. The final selector LIV is now raised to the level corresponding to the interruptions at the subscribers station. The relay V1 is energized during this impulse train, because each time the relay A2 falls back the contact 37002 is closed and so short circuits winding II of relay V1, thus rendering the relay slow acting, and it only releases its armature when the relayA2 has been released for some time, that is to say at the end of the impulse train. Thereupon the relay U is energized over: earth, oflnormal contact'38k closed at the first lifting step, contacts 39111., 4001, winding I ofrelay U, shaft contact 3610, lifting magnet HM1,

battery, earth. The lifting magnet HM1 is not operated in this circuit. On being operated, the relay U opens contact 35wand closes contact 4114. p

The next train of impulses transmitted by the subscriber N now operate the rotary magnet DM2 over contact 34(12 in the circuit: earth, contact 34002, winding I of relay V1, contact 41a, contact 42172, rotary magnet DM2, battery, earth. The final selector LW is positoned onto the-wanted line by the last impulse train, during which therelay V1 The lifting magnet HM and relay IOU is maintained ener 'zed. During this time the relay U is locke up over: earth, contacts] 4301, 44a, 452:1, winding II of relay U, battery, earth. When relay V1 falls back at the end of the impulse train, the contact 45101 is opened and contact 4601 is closed. Al-

' the relay U does not fall back, because it is slow to release and over earth, contacts 4301, 441a, 'v1,'winding II of relay U, battery, earth, it again receivescurrent owing to winding III of relay V1 being energized when the circuit for relay P2 is established in the manner to be described later.

It will be assume'd'that the wanted subscribers line is arranged in the same-manner as the main station N shown in Fig. 1. If it be .free, the relay' P2 is energized over contacts 4301, 4410, 461:1, windings II and I of rupter RUl over: earth, rela relay P2, wiper c4 of the final selector LW, windin II of relay T-of. the wanted partys call see er, battery, earth.

1 Relay P2 is operated and by closing contact 47322. it short circuits winding II of relay P2, thus preventing'another final selector being set on the seized subscribers line. Switching through at the final selector LW is effected at the contacts 52102 and 53122. Furthermore, contact 42 2 is o ened and contact 48122 is closed. ielay' 1 receives energizing impulses from the relay interinterrupter RUl, contact 49a, winding II of relay'V1, contact 50y, contact 48112, rotary magnet DM2, battery, .earth. The rotary magnet DM2 is not operated over this circuit; but the closing of contact 45421 causes the relay U to again receive current over its locking circuit as previously mentioned (earth, contacts 4301, 44a, 45'v1, windin II of relay U, bat tery, earth). Being 's ow acting-,relay U A does not follow the interruptions of relay V1. Contact 51111 sends ringing impulses from the ringing machine Rltftothe lead a. When the wanted station answers by taking down the receiver, the switching means A also for this station is energized over one lead, namely over: earth, choking coil D2, subscribers loop-of the wanted station, relay A,-lead a3, wiper a4 of the final selector LW, contacts 52112, 54 v1,'windin II of relay A2, battery, earth. Relay A o the wanted station is operated and closes the contact corresponding to contact 2a, thereby discon necting ringin current, because the relay Y at the final se ector LW is energized over: earth, battery, choking coil D5, contact 20 of the wanted station, lead 63, w1 r 64 of the final selector, contact 53122, re ay Y, earth. By opening contact 503 ,the 'relay Y interrupts the circuit of relay V1. v In this case likewise over the one lead (lead a) amimpulse is sentfor efiecting a switching operation and it is passed on over the other lead, thus the impulse for disconnecting ringover the other lead.

At the endof the conversation, when the calling subscriber hangs up thereceiver, the

relays A and A1 fall back owing to the interruption at the subscribers station. On be-' though its locking circuit is thereby opened,

mg short circuited over contact 14a1, the re ay C releases its contacts, so that its own circuit is opened at contact 130 and at contact 1250 is opened the circuit of relays 'P and T.

Contact 1240 short circuits relay P1,fwhi ;1i

falls back and at -contact'25p1 opens the' cir -i cuit of relay 01, while at contact 19121" it again closes the circuit of the rotary magnet" DMl. The latter is energized and moves the.

wipers of the. group selector GW 011 one step while over contact 21dm1 it energizeslthe relay V. The rotary magnet DM1 and relay V interact until the group selector GW.

reaches its, extreme rotary position, from which it is mechanically restored to its normal position, opening contact 2070 and there by opening the circuit of the rotary magnet DMl.

The opening of the circuit of relay G1 at contact 3101 prevents the relay C1 being again ener ized and so prevents the final selector L being again seized during the releasing operation, because the shaft contact 2440 is also open until the wipers of the final selector LW have reached their normal position. Furthermore, after relay P2 has been released owing to the opening of the contact 4 4301, the followingcircuit is established for the rotarymagnet DM2 of the final selector:

earth, ofl-normal contact 12310, contacts 122-01,

12101, 120a, 42112, rotary magnet DM2, bat

tery,- earth. On being energlzed, the rotary magnet DM2 moves the wipers ofthe final selector LW one step further and by closing contact 117 dm2 it energizes the relay U over:

earth, contacts 119u, 11801, 117dm2, winding II of relay 'U, battery, earth. The latter at contact 119a opens its own circuitand at contact 120a that of thero'tary magnet'DM2. As relay U is slow'tb release, there is time for the circuit of the rotary magnet DM2 to be opened. But it is then again energized over the before-described circuit and causes the final selector arms .to be moved on and the rela --U to be energized. This'a'ction is repeate until the final selector LW has reached its extreme rotary position from which it is mechanically restored to normal,

120 opened and the circuit of rotary magnet 7 whereupon the ofi-normal contact. 12370 is DM2 cannot be again established.

The setting upof a'connection between the subscriber N3 in Fig. 2 and another subscriber bed.

will now be descri Thesubscribers line is so arranged-that signals can be sent over one lead, The: signal transmission is efiected in the following manner. Ator near "the instrument of the subscriber N3 thereis akeyX associated with the signalling device the key is pressed when a signal is to be transmitted. It can be used for giving a, fire-alarm, etc. On pressing the key X, the following circuit is established for the relay AR: earth, key as, relay AR, relay interrupter RU2, battery, earth.

Relay AR is energized by each impulse and by closing contact 55m, it establishes the following circuit for the relay S: earth, contact 55m, choking coil D20, lead 55, choking coil D21, relay S, battery, earth. Relay S is energized in the same manner as relay. AR, and the lamp L is flashed by the opening and closing of contact 568. The lamp L is located at an alarm receiving position, which takes the necessary steps in known manner.

If the subscriber N3 wishes to make a call to asimilar subscriber and for that purpose takes down his receiver, the relay A3 is energized in the following circuit earth, choking coil D22, subscribers loop of the station N3, lead (15, relay A8, battery, earth. This initial impulse received over the lead (15 is transmitted over the lead 6 by the closing of con? tact- 57a3, because thereby the relay R1 of the prcselector VWV is energized over: earth, relay R1, contact 58t2, cont-act 57a3, choking coil D23, battery, earth. Relay R1 is operated and at contact 5991 closes the circuit of the rotary magnet DM3 over: earth, relay interrupter RUEB, rotary magnet DM3, contact 60232. contact 591 1, wiper (Z7 of the preselector found, the following circuit is established ing the contacts 65252 and 66t2,

VVV in the normal position, battery, earth.

The preselected VWV is thereby positioned onto a free group selector GW.

When a free group selector GWl has been earth, off-normal contact 61%, contacts 62 02, 636, wiper 07 of the preselector VW, wind- -ings I and II of relay T2, contact 5911, segment 1-10, wiper d7 of preselector VW, battery, earth. The relay T2 is operated and by opening the contacts 58t2 and 6422 and closit switches through the line and operates the relays A4 and 13 over the following circuits: (1) earth, battery, relay A4, wiper .'a7 of preselector VW, contact 65t2, lead. a5, loop of-the subscribers station N3, choking coil D22, earth; and (2) earth, contact 67 a4, winding II of relay B, wiper 57 of preselector VW, contact 66t2, contact 57 1'3, choking coil D23, battery, earth. The opening of contact 67a4 removes the short circuit from winding I of relay B, which is thus maintained energized over both windings. I

The opening of contact 631) removes the short circuit from 1'elay'C2', which is operated and by closing contact 6802 establishes a circuit for the relays C2 and T2, which is independent of the contact 6202 and off-normal contact 6170.

' impulse train,

When the subscriber transmits the first the relay A4 is released at each impulse in the before-described circuit. The

relay A3 associated with the subscribers line and the relay B controlled thereby are not affected by the interruptions at the subscribqers station, because they are slow in falling selector GWl is raised to the wantedleve'l in accordance with the interruptions at the subscribers instrument. Relay V2 only falls back at the end of the impulse train, because it is short circuited by contact 71a4 at each impulse of the train and thereby is rendered slow acting. On falling back at the end of the impulse train relay V2 at its contact 7 5 02 establishes the following circuit for the rotary magnet DM4: earth, contact 73123, offnormal contact 7470 which is closed at the first lifting step, contact 7 502, rotary magnet DM4, battery, earth. The rotary magnet DM4 is operated and causes the wipers of the group selector GWl to move on one step. At the same time the operation of the rotary magnet DM4 causes the contact 77 dm4 to be opened and contact 7 6dm4 to be closed, thus establishing the following circuit for the relay V2: earth, contact 7 6cZm4, winding I of relay V2, lifting magnet I-IM2, battery, earth. The lifting magnet HM2 is not operated in this circuit. The opening of contact 75o2 interrupts the circuit of the rotary magnet DM4. Hence, contact 76dm4 is opened and contact 7 7 dm4 is closed. The opening of the shaft contact 72w at the first rotary step prevents the relay V2 being rendered slow acting when contact 77 (19124 is closed. Relay V2 is deenergized and contact 7502 returns to its normal position and the wipers of the group selector GWl advance another step. This inter-action between relay V2 and the rotary magnet DM4 continues until the group selector GWl has found a free final selector LWl. Thereupon the following circuit is established earth, contacts 7802, 7 9014, windings II and I of relay P3, wiper 08 of group selector GWl, elf-normal contact 8070 of final selector LWl, winding II of relay G8, battery, earth. Relays P3'and C3 are operated. Contact 7 3113 opens the "circuit of the rotary magnet DM4, while the closing of contact 81 3 short circuits the winding II of relay earth, contact 86a5, winding I of relay V3, contact 87u1, shaft contact88'w, lifting magnet HM3, battery, earth. Thereby the final selector is set onto the wanted level.

The relay V3 located in the circuit of the lifting magnet'HMS is maintained energized during the impulse train because each time relay A5 falls back the winding II of relay V3 is short 'circuited at contact 89115, thereby rendering the relay V3 slow to release. The relay V3 having fallen back at the end of the impulse train, the following circuit is established for the relay U1: earth, off-normal contact 9070, contacts 91 03, 9203, winding I of rela U1,. shaft contact 88w, lifting magnet H 3, battery, earth', The lifting magnet HM3 is not operated in this circuit. On being operated, the relay U1 opens the contact 87 M1 and closes the contact 93u1.

When the subscriber transmits the last impulse train, the relay A5 is operated in accordance with the interruptions at the subscribers station as before described, and thereby the rotary magnet DM5 is operated over: earth, contact 86a5, winding I of. relay V3, contact 93ml, contact 94324, rotary magnet DM5, battery, earth. During this impulse train likewise the relay V3 remains operated; and the relay U1 is maintained energized over: earth, contacts 9503, 96141, 9703, winding II of relay U1, battery, earth; because the circuit of winding I of relay U1 is opened at the shaft contact. 88w when the firstrotary step has been taken. Testing takes place i when the relay V3 falls back at the end of the impulse train. The relay U1 being slow acting it remains operated until the relay'V3 is again operated by its winding III after testing has beeneifected. The circuit for the test relay P 1 extends over: earth, contacts 9503, 96101, 98 03, wind'ings'II and I of'relay ,Pl, wiper 09 of the final selector LWl, lead 010, wiper 0 of the preselector of the wanted line, windings I and II of relay T at the preselector, wiper d, battery, earth. I Relay P4. at the final selector LWl isoperated and by closing the contacts 99294 and 100204 it effects the switching through at the'final selector.

Furthermore, contacts 94174: is opened and contact 101.124 is closed, while contact 10212 1 short circuits the windin II of relay P4,

thus preventing any other nal selector being positioned on the subscribers line.

It is assumed, as previously mentioned, that the wanted station is arranged in the same manner as the calling station shown in Fig.

2. Relay V3 is energized by impulses over: earth, relay interrupter RUL, contact 103101,

winding IIIof relay V3, contacts 1043 1,

101p4, rotary magnet DM5, battery, earth, but the rotary magnet DM5 is not operated. Relay U1 how receives current over: earth, contacts 9503, 96201, 97'v3, winding II of relay U1, battery, earth. Relay U1 being slow to release it does not fall back when relay V3 is being energized. by impulses. -The relay- V3 being operated at certain intervals, ring- Y ing current is sent from the ringing machine earth, battery, chokingcoil D23, contact 57 a3,

lead 610, wiper '69 of the final selector LWl contact99pl, relay Y1, earth. Relay Y1 is operated and by opening the contact 1043 1 it interrupts the circuit of the relay V3. Thus,

contact ing contact 03, the circuit extending over 2 no more ringing current is sent out. Relay U1 also falls back, because relay V3 is no more energized. The subscribers are now interconnected.

At the end of the conversation, when the, calling subscriber N3 hangs up his receiver,

the relay A3 of his line is released and by opening the contact 57a3. it releases the relay B at the group selector GW1. Relay B short'circuits the relay G2 at contact 63?), hence relay C2 also returns its contacts to normal. At contact 10702, the relay C2.

short circuits the relay P3, which falls back and again energizes the rotary magnet DM4 over: earth, contact 7 3172, off-normal contact 74%, contact 75422, rotary magnet DM i, battery, earth; hence the wipers of the groups selector GW1 advance one step. At the same time the contact 7 6dm4 is closed by the rotary magnet DM hence the relay V2 is energized 1 over: earth, contact 76dm4, winding I of relay V2, lifting magnet HM2, battery, earth but the lifting magnet HM2 is not operated in this case. Relay V2 opens the contact 7 5122,- thereby interrupting the circuit of the rotary magnet DM4.-. The contact. 760912. 1 is also opened again, hence the contact 75412 returns to the normal position. Thereupon the rotary magnet DM4= again receives current over the before-mentioned circuit. This is repeated until-the group selector GWl leaves the last contact of the row and the wipers of the switch are mechanically returned to the normal position. The ofi-normal contact 7470 is then opened so that DM4 cannot. be.

energized again. I

When the relay G2 was short'circuited by contact 63?; as previously mentioned, it fell back and its contact 10702 short circuited the relay P3 which also fell back. Thereby the circuit of relay G3 was opened and it returned its contacts to the normalposition, so that the rotary magnet DM5 is energized over: earth, off-normal contact 11070, contacts 11103, 11203, 113141, 94194, rotary magnet DM5,

battery, earth; and the wipers of the final selector are advanced a step.

When the rotary magnet DM is operated, the relay U1 is energized over earth, contacts 114u1, 11503, 11'6d'm5, winding II of relay U1, battery, earth. On being operated, relay U1 at contact 113141 opens the circuit of the rotary magnet DM5 and at contact 114. 101.

it opens its own circuit, hence relay U 1 falls back again and the before-described c1rc u1t of the rotary magnet DM5 is closed again, so

' that the wipers of the final selector are advanced one step further. This continues until the switch has left the last contact in the row andthe final selector is then returned to the normal position by mechanical power in known manner.

Fig. 3 (at the bottom of Fig. 1) shows a further arrangement of the switching means A belonging to the connecting up point and arranged to cut off the ringing current; it receives the initial impulse over one lead and sends it on over the other lead. In this modification, when the subscriber answers an incoming call, the relay A is energized over the lead a, and the initial impulse thereby given for disconnecting the ringing current is sent on over the other lead 1) at contact a to operate the ring-cut off relay, such as Y1 of Fig.

. of one conductor of a line extending to a subscribers station is used for special purposes,

-means at said station for transmittin signals over the other conductor of said line, and means for repeating said signals over a part of'the first conductor not being used for special purposes.

2. In a telephone system, a substation, a.

line extending to said substation comprising two conductors, a portion of the first of said conductors bein used for special purposes, means at said su station for transmitting impulses over the second of said conductors to set up a telephone connection, and means for repeating said impulses over a portion of said first conductor not being used for special purposes in order to assist in the establishment of the connection. I r

3. In a telephone system, a line outgoing from a subscribers station, means for extendingsaid line to a line rela means including a calling device at sai station for intermittently energizing one winding of said relay over one conductor of said line, a second relay in said conductor energized in series with said winding, a second winding on said line relay, and means. responsive to the operation of said second relay for energizing said second winding over the other conductor of said line.

4. In a telephone system wherein one portion of one conductor of a line extending to a subscribers station is being used for special purposes, said portion being insulated from the remainder of the conductor by condensers,

a line relay having two windings, means at said station for transmitting signals over the second conductor of said line to the first winding of said line relay, and a relay in series with said first winding for repeating said signals to the second winding of said line relay over a portion of the first conductor not being used for special purposes.

' 5. In a telephone system, a subscribers station, a line extending to said station comprising two conductors, a portion of the first of said conductors being used for special purposes and being insulated from the remainder of the conductor by condensers, a connector having access to said line, means in said connector for transmitting ringing current over the second conductor of said line, a relay in said second conductor responsive to the removal of the receiver at said substation, and means controlled by said relay over a portion of the first conductor not being used for special purposes for disconnecting said ringing current.

-6. In combination, a line comprising two conductors, a line relay having two windings, a second relay in series with one conductor of said line, the first winding of said line relay, and a battery, and contacts on said second relay for closing a circuit for the second winding of said line relay over the other conductor of said line.

, 7. In combination, a line relay having two windings, a second relay in series with the first winding of said line relay, means for trans mitting impulses to said second relay and the first winding of said line relay, and means controlled by said second relay for repeating said impulses to the second winding of said line relay.

8. In a telephone s stem wherein a portion of one conductoro a line extending to a subscribers station is used for special purposes, aconnector havin access to said line, means in said connector. or transmitting signallin current over the second conductor of said line, nad means responsive to theremoval of the receiver at said station for efiecting the disconnection of rin 'ng current over a portion of said first con uctor not/being used for special purposes.

9. In a telephone system wherein a portion of one conductor of a line extending to a subscribers station is used for special purion - over the second conductor of said line, and

I ries in one conductor of said line whereby poses, a line finder having access to said line, .means responsive to the initiation of a call at said station for transmitting an impulse means for repeating said impulse over a portion of the first conductor not being used for special to eifect the starting of said lme fin er.

a 10. In a" tele hone system, asubscribers line, a line find start relay in said finder, means-responsive to the initiation of a call over said lme for transmittin a starting impulse over one conductor of salcl line, means for, repea said impulse over the other conductor of s id line, and means responsive to the repeated impulse for energizing said start relay. v

11. In a telephone system, a subscribers station, a line extending from said station to an exchange, condensers connected in 'se-.

a section thereof is isolated'from the remainder of the conductor to be-used for special. purposes, means for completing telephone connections to and from said line, and means for supplying talln'ng battery tosaid Qation from said exchange. 1

12. In a telephone system, a subscribers station, a line extending from said station to an exchange, condensers-connected in series in one conductor of said line whereby a section thereof is isolated from the remainder of the-conductor to be used for special purposes, a line relay insaid exchange having two windings, means for bridging said relay across said'sub'scribers line in series 1 with a batte and means including a calling device to sai subscribers station for control- 4 ling said line relay to establish a telephone connection.

In witness whereof, I hereunto subscribe my name this 9th day of Jul ,A. D. 1929.

. LAN GER.

or having access thereto, a

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