US1941254A - Automatic telephone system - Google Patents

Description

Dec. 26, 1933.

A. FLAD AUTOMATIC TELEPHONE SYSTEM Filed July 18, 1932 Patented Dec. 26,

' iii? AEJTDMATIC TELETHONE SYSTEM Artur Fla-cl, BcrlinyGermany, assignor to Siemens lilalslie Alrtienges'ellschaft,

Wernerwerk Siemensstadt, near Berlin, Germany Application July is, 1932, Serial No. 623,036, and

in Germany September 26, 1931 I 1 15 Claims. (01. Nile-18) The present invention relates to circuit arrangements for testing in telephone systems pr vided with two-wire switches and two-wire junction lines. In known arrangements of this type complicated wiring is necessary for this purpose due to the fact that potential must be applied to the two speaking leads all the time-e-that is to say, both prior to as well as during a connection. loConsequently, for example, quite'a number of difierent equalizing'resistances have to be inserted in the individual branches to set up the necessary current ratios in the multiply wired selecting circuits requiredto prevent double connections. In addition, this type of arrangement involves considerable difficulties in the transmission of switching operations; particularly after a connection has'been completed, such as, for example, metering, due to the above-mentioned fact that a potential is permanently applied to both the leads and consequently cannot be used for such switching operations unless-special steps to this end aretaken." f

The present invention eliminates these difii- .culties in a simple manner by causing the junction lines to be tested in the switches whether idle or busy with the aid of a switching means disposed between the two speaking leads and caused to function by means of a gas discharge or neon tube influenced over said junction lines if idle.

The invention with advantage makes use of the arrangement known per se in which the release is effected with the aid of a relay to be energized two leads of 'the junction line during operation, with the result that said junction-line can be adequately guarded against seizure switches and whereby itis possible to transmit switching operations over the two leads of the line. 7 7 An embodiment of the invention is shownin the accompanying drawing. I

A connection between the subscribers Tn and Tnl will now be described in conjunction with Fig. 1. Switching apparatus of no importance for the understanding, of the invention has not been shown. When the subscriber Tn lifts his receiver, his preselector VW startsoperating in known manner and hunts for a line leading to an idle first group selector. When found, relay R in the preselector VW and relay C 'in'the first group selector IGW are energized in the following circuit: earth, battery, windings I and II of relay T, c-wiper of the preselector VW, winding I of over a neon lamp. This completely releasesthe from other relay C, off-normal contact 17c, earth. Relay T brings the preselector to rest on the idle line in known manner and switches through the two speaking leads. Relay'ZR, which lies parallel with winding II of relay Tis not energized inthe 0 test circuit. After the two speaking leads have been switched through, the impulse-receiving relay A in the first group selector IGW operates over windings I and II and the closed subscriber s line loop. Relay 0 is placed in the following 5 looking circuit: earth, battery, contact 30, winding II ofrelay C, contact 5a, winding I of relay V, earth. Relay V also operates in this circuit. RelayC, by closing its contact 170 prepares'the vertical stepping circuit, by closing contact 250 it prepares the test circuit and by closing contact 90 prepares for repeating impulses. Relay V, by closing its contact 241) prepares a locking'circuit for the test relay P and by closing its contact 1922 the rotary stepping circuit. 1 J 7 By manipulating his dial, the subscriber Tn now transmits the first impulse U series, which causes the subscribers line loop to be alternatively opened andclosed in known manner and consequently also the-circuit'for relay A in the first group selector IGW to be intermittently opened and closed. Relay A operates accordingly' and transmits the impulses to the vertical magnet over the following route: earth, contacts 170, 16a, rotary off-normal contact 1520, winding 35 of vertical magnet l-I, battery, earth. Due to the opening of contact 5a on the first relapse of relay A, the short circuit for winding II of relay P is removed. This relay then remains energized during the impulse transmission due to its winding I being short circuited by means of the closed .contacti43p. After the first vertical step the circuit for the release magnet M is prepared by .the closing of the off-normal contact 44k and the rotary stepping circuit also is prepared due tothe closing of the off-normal contact 21k. Further, due to the opening of the off-normal contact 170 'on the first vertical step, the circuit for winding 1' of relay 0 is cut off. The circuit for relay T r in the preselector VW, however, is maintained over earth, resistance Wi, contact 47m of'the release magnet M. Relay A is re-energized at the end of the first impulse series. By means of contact 5a it permanently short circuits winding II of relay P, which consequently relapses and closes. 5 the following circuit for the rotary magnet of the first group selector IGW: earth, interrupter RU,

off-normal contact 21k,- contacts '20p, 19',

winding of rotarymagnet D,- battery, earth.

The first group selector hunts freely for an idle line in the level to which it has been raised by the first impulse series. This line may be found to be the junction line VL which leads to a second group selectorIIGW. When found, the following circuit for the neon lamp GL is closed: earth, contact 2701 in the second group selector IIGW, b-lead of the junction line VL, b-wiper of the first group selector, contact 250, neon lamp GL, winding I of relay P, a-wiper of the first group selector, a-lead of the junction line VL, contact 2601, windingII of relay C1 in the second group, selector IIGW, battery, earth. The battery B has a sufficiently high potential to light the neon lamp; for example, 90 volts. When this neon lamp has been lighted, relay C1 in the second group selector IIGW and relay P in the first group selector IGW operate in the aforesaid circuit. Relay P in the first group selector brings the switch to rest by opening its contact 201). It is then placed in the following locking circuit by closing its contact 23p: earth, winding III of relay P, rotary oft-normal contact 22w (closed on the first rotary step), contacts 23p,

241), battery, earth. The closing of contacts 10p and 11p switch through the two speaking leads to the second group selector.

' As mentioned above, relay C1 in the second group selector IIGW operates, is disconnected from the speaking leads due to the opening of contacts 2601 and 2701 and, as before, is placed in the following locking circuit: earth, contacts 3401, 33b1, winding I of relay C1, battery, earth. The closing of contact 2901 connects the impulse-receiving relay A1 to the a-lead. The closing of contact 3201 places winding I of the test relay P which lies in series with the neon lamp GL1 between the two speaking leads. A locking circuit for winding II of the test relay P1 is pre- .pared by the closing of contact 3701. The closing of contact 2801 causes the release relay B1, which is connected in series with the neon lamp GL2, to be connected to the b-lead.

,On the succeeding impulse series for the setting of the second group selector IIGW, relay A of the first group selector IGW is again intermittently energized and de-energized; By closing its contact lot it applies earth intermittently to the a-lead and thus causes the impulse-receiving relay A1 in the second group selector IIGW to operate over the following circuit: earth, contacts 7a, 90, 10p, a-wiper of the first group selector, .a-lead of the junction line VL, contact 29c1',

winding of relay A1, rotary ofi-normal contact 45w, battery, earth. Relay A is energized and transmitsthe impulses in known manner to the vertical magnet (not shown) of the second group selector. At the end of the impulse series the group selector hunts for an idle line leading to a final selector. The impulse circuit for this operation being of no importance for the understanding of the present invention, it has been omitted. When the group selector has found a line leading to an idle final selector, for example, the shown final selector LW, the following circuit is closed for the neon lamp GL1: earth, contact 3902, b wiper of the second group selector IIGW, winding I of the test relay P1, neon lamp GL1, contact 3201, a-wiper of the second group selector IIGW, contact 3802, winding of relay C2, battery B3, earth. The battery B3 applied to the final selector LW has a sufficiently high. voltage to light the neon lamp GL1. After said lamp has been lighted, relays C2 andPl operate in this circuit. Relay P1 brings the second group selector to rest in known manner and, by'closing its contacts contacts 3701, 36121, rotary off-normal contact 35w, winding 11 of relay P1, battery, earth.

As previously mentioned, relay C2 in the final selector is caused to operate. This relay, by opening its contacts 3802 and 3902, is disconnected from the speaking leads after having been placed in a locking circuit in the manner described for the first and second group selectors. The closing of contact 4202 connects the release relay B2, which lies in series with the neon lamp GL3, to the b-lead. Theimpulse series for the setting of the final selector LW to the required subscribers line are now transmitted. The circuits concerned in this operation are or" no importance for the invention and, th refore, have not been shown. When the subscriber Tnl answers, the feeding bridge relay A2 operates in the following circuit: earth, winding I of relay A2, b-wiper of the final selector LW, line loop for the subscriber Tnl, d-wiper of the final selector LW, winding II of relay A2, battery, earth. A potential is now applied to the b-lead over the closed contact ila2 and position 1070f a not showncontrol switch and earth in the same manner is applied to the a-lead over the closed contact 40a2 and the control switch set to positionlO. When the subscriber Tn, after having finished the call, replaces his receiver, relay A in the first.

group selector IGW restores, due to the inter ruption of the subscribers line loop. Relay A, by means of its contact 4a short circuits winding II of relay 1. This relay relapses and by opening its contact 30 I of relay V, which remains energized in thefollowing circuit: earth, contact 4M2, control switch set to position it, a-wipe'roi' the second group selector IIGW, contact BGpl, a-lead of the him opens the circuit for winding tion line VL, a-wiper of ti e first group selector IGW, contacts 192 6c, winding II of relay ,V,'battery, earth. The following circuit for relay. Z'in the first group selector IGW is closed after relay C has released: earth, battery, contact lla2,'control sw' ch set to position 10, b-wiperofthe-second i group selector IIGW, contact I-Elpl, b-wiper oi the first group selector IGW, contacts 11;), 130,

winding of relay Z, off-normal contact 1415, earth.

Relay Z operates and by closing its contact 22 applies direct earth to metering relay ZR in the preselector VW to be energized due to the'increased voltage. On the aticn of reiay'Z, winding II of relay V is short circuited by meansof contact 82, so that it therefore releases with slow action. During its release period the following circuit for the release relay B1 in the second group selector IIGW and relay E2 in the final selector LW is closed: earth,

alternating current source of supply WQ, contacts lip, b-wiper of the first group selector IGW,-

b-lead of the junction line VL, contact 2801, neon GL2, winding of relay Bl, battery, earth and parallel thereto, contact 31301, vb-wiper of the second group selector IEGW, contact i202, neon lamp GL3, winding of relay B2, battery, earth. The neon lamps GL2 and GL3 are lighted due to the additional alternating current from the alternating current source of supply WQ and consequently generate aidirect current for relays B1 and B2. This circuit is opened by contact lip on the release of relay P in the first group selector IGW. Further, on the relapse of relay 'P, the following circuit for the release magnet M is closed: earth, off-normal contact 44k, contacts the c-lead, thus causing the (13p, "18, winding of the release magnet M, battery, earth. The first group selector IGW is restored to normal position when the release magnet M is energized. Contact 47m then opens the test circuit to the preselector VW and 'in this manner initiatesthe release of the latter switch. T

On the energization of relay B1 in thesecond group selector IIGW the locking circuit for winding I of relay C1 is interrupted due to the opening of contact 33111;. Relay C1 therefore restores and by opening its contact 3701 breaks the locking circuit for winding II of the test relay P1,. so that it relapses andat its contacts 30101 and 31311 opens the two speaking leads and in a manner similar to that described for relay P in the first group selector IGW initiates the release of the second group selector IIGW.

Due to the energization of relay B2in the final selector LW the locking circuit for relay C2 is opened, causing this relay to release and so initiate the release of the final selectorLW in known manner after the subscriber Tnl'has replaced his receiver. I 7' A further form of construction of the invention is shown in Fig.2, in which relay C1 in the second group selector IIGW is not disconnected from the two speaking leads by means of its own contacts.

. relay C1, moreover, is not cut off from said speaking leads until after the first vertical step on the part of the switch at which the off- normal contacts 54k and 55k are opened. In order to prevent a multiply wired switch from testing the seized junction line VL between the actual seizure and the first impulse, the test relay P in the first group selector IGW short circuits the neon lamp GL over its own contact 52p and the choke Dr. The

test relay P of another testing switch cannot be operated due to the fact that the voltage drop at the multiply wired contacts of the switch is so great in consequence of the current passing over contact 52p and the choke Dr that the voltage for the lighting of the neon lamp of a parallel testing switch is insufficient.

What is claimed is:

1. In an automatic switch, two talking conductors, means for causing the switch to'hunt for an idle trunk, and means including a gas discharge tube connected across said conductors for stopping the switch when an idle trunk is found. a

2. In a telephone system, an automatic switch, a group of trunks, means for maintaining a definite potential on each trunk while idle, means for moving the switch over the group of trunks,

means including a neontube adapted to flashover at said definte potential for testing the trunks passed over for their busy or idle condition, and means controlled by said last means for stopping the switch on an idle trunk. V

3. In a telephone system, an automatic switch, a group of trunks, each trunk having normally connected thereto a source of current of a particular potential, means for moving the switch over the group of trunks, means including a neon tube adapted to flash-over at said particular po tential for testing the trunks passed over for their busy or idle condition, and means responsive to said tube flashing-over for causing the switch to seize a trunk and for disconnecting said'source of current therefrom.

4. In an automatic switchequipped withtwo line wipers, means for automatically moving the Wipers over a-group of trunks, a relay and a gas discharge device connected across the linewipers in series, said device controlling the energization means for causing the switch to hunt for an idle trunk, a relay and a' neon tube connected in series across the outgoing conductors, means for op erating the tube and relay responsive to the finding of an idle trunk, and means controlledby said relay forpreventing further huntingby the switch and for connecting-said incoming conductors to's aid outgoing conduct ors. i I 6. In a telephone systemfan automatic switch, a test circuitincluding-a neon tube and a relay in said switch, 'a'tr'unk accessible to said switch, a source of current normallyconnected to said trunk, means for operating the switch into en gagement with said trunk whereby said current source is connected to the test circuit tooperate said tube and said relay, and contacts controlled by said relay foreffecting the seizure of said trunk. V I 1 7. In a telephone system, automaticswitches, atrunk, a source of'current of a particular potential normally connected to the trunk, means for operating one of the switches into engagement with the trunk, means including a neon tube adapted to flash-over at said particular potential for causing the switch to seize said trunk, and means responsive to the seizure of the trunk for disconnecting said current source to prevent a subsequent seizure of the trunk by another switch.

8. In a telephone system, automatic switches, a supervisory relay in each switch, a trunk accessible to said switches, a source of current of one potential normally'connected to the trunk, means for operating one of said switches to extend a connection tothe trunk, means in said one switch including a neon tube adapted to flash-over in consequence of the connection of the switch with said source of current via the trunk for causing the switch to seize the trunk, means responsive to the seizure of the trunk for disconnecting said current source from the trunk to prevent subsequent seizure by another switch, a second source of current of a potential ineffecequipped witha pair of'wipers, a trunk comprising two talking conductors accessible at one end to the switch via said wipers, a relay, and a source of current connected to the other end of the trunk conductors, means for operating theswitch to bring said wipers into engagement with the trunk conductors, a test circuit including a neon tube and said wipers in the switch, said tube being adapted to flash-over in consequence of the connection with said current source whereby the seizure of the trunk and the operation of said relay is effected, and means controlled by the. re-' layfor disconnecting said current source from the trunk to mark the trunk busy.

10. In a telephone system, a trunk comprising two talking conductors, a relay, connected to one end of said conductors in series with a source of current, means for operating the relay responsive to the seizure of the trunk at the other end thereof, and means controlled by the relay for disconnecting itselfand the current source from the trunk conductors to prevent a subsequent seizure of the trunk,

ll. In a telephone system,l ines each of which is maintained at one potential when idle, at another potential during part of the time when busy, and at no potential during the remainder of the busy time, and means for testing the lines including means effective to draw current from lines on which said one potential is present.

12. In an automatic switch, talking conductors, operating means for selecting a group of trunks, a relay, a neon tube, an impedance, means for connecting said relay and said tube in series across said talking conductors for testing said trunks, contacts controlled by said relay for stopping the switch on an idle one of said trunks, and contacts controlled by said relay for shunting said tube with said impedance to mark said one trunk busy.

13. In a telephone system, an automatic switch including two talking conductors, groups or" trunks accessible to the switch, means for transmitting a series of impulses to the switch to set the same in selective relation with one of said groups of trunks, means including a relay and a gas discharge tube bridged across the talking. conductors of the switch for causing the switch to connect with an idle trunk in said'one group, and means in the switch for repeating impulses over the trunk connected with. I

14. In an automatic telephone system, selective switches, means for operating a plurality of switches-in tandem to establish a two-conductor metallic talking circuit, means for operating other of said switches in attempting connection with said talking circuit, and testing means in said other switches including neon tubes controlled over the talking circuit for preventing 'the'establishment of the attempted connections without interfering with the talking circuit.

15. In an automatic telephone system comprising selective switches in which the usual third conductors extending through" and between switches are omitted, means including a neon tube in each switch whereby the testing functions are controlled overthe talking conductors without interfering with conversation, and means including a second neon tube in each switch whereby the release of the switches is controlled over the talking conductors.

ARTUR. FLAD.

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