US2182482A

US2182482A - Automatic telephone system

Info

Publication number: US2182482A
Application number: US154977A
Authority: US
Inventors: Lurk Hans Joachim
Original assignee: Siemens and Halske AG
Current assignee: Siemens and Halske AG
Priority date: 1936-08-04
Filing date: 1937-07-22
Publication date: 1939-12-05
Anticipated expiration: 1956-12-05
Also published as: US2153319A

Description

Dec. 5, 1939. LURK AUTOMATIC TELEPHONE SYSTEM Filed July 22, 1957 2 Sheets-Sheet'l FEG.

INVENTOR. HANS JOACHIM LURK BY b ATTORNEY.

Dec. 5, 1939.

H. J. LURK AUTOMATIC TELEPHONE SYSTEM Filed July 22, 1937 FIG. 2

2 Sheets-Sheet 2 90x 91h 89d 8 F 541 92p 88 3 94p :2,5,8 1 '16 12'4654 BUSY TONE INVENTOR.

HANS JOACHIM LURK ATTORNEY.

Patented Dec. 5, 1939 ATE AUTOMATIC TELEPHONE SYSTEM Hans Joachim Lurk, Berlin-Siemensstadt, Germany, assignor to Siemens & Halske Aktiengesellschaft of Wernerwerk, Siemensstadt, near Berlin, Germany Application July 22, 1937, Serial No. 154,977 In Germany August 4, 1936 13 Claims.

The present invention concerns a circuit arrangement for zone metering in remote communication systems and more particularly in automatic telephone systems in which the zone is determined by numbers comprising different numbers of digits.

In such arrangements it is necessary to provide switching means which render impossible any further influencing of the zone characterizing devices after the reception of the impulse train which completes the characterization of the zone. It may happen, however, that the zone characterizing devices are brought by impulse trains into positions over which no zone 1Q; determination can take place as can occur if the zone characterizing devices are set by numerical impulses which do not correspond to the prescribed characterizing digits. The determination of the zone can also be made impossible in the event of faults in the path serving for zone characterizing (a break in the zone cable).

In order now to prevent an unnecessary setting oi the zone characterizing devices in such cases and to prevent as rapidly as possible any further setting up of the call, switching means are associated with the zone characterizing devices, according to the invention, which directly after the impulse train by which the zone characterizing devices are either brought to a position enabling the zone to be determined or are brought to a position which does not allow of such a zone determination, either enable the establishment of the call to proceed in the one case or prevent it in the other case, while in 1 both cases preventing any further influencing of the zone characterizing devices.

An embodiment of the invention is represented in the drawings, comprising Figs. 1 and 2.

The main parts of the repeater shown are as follows:

1) Rotary switch DG.This rotary switch is set in a definite manner by the first numerical impulse train transmitted by the calling subscriber and operating on the repeater. According to the number of digits necessary for determining the zone of the call a wiper of this rotary switch is either directly connected toa zone contact or a wiper of a two-motion switch is connected up by a wiper of this rotary switch.

(2) The two-motion switch.The two-motion switch with its vertical magnet HH and its rotary magnet DD is set by the second and third impulse train operating on the repeater. In particular cases it takes up a fourth digit.

(3) The time switch DZ.-The time switch (01. 179-'7.1) I v is influenced by a time switching device which operates so that it receives a stepping impulse every minute. The time switch determines in the present embodiment the moment for transmitting a definite number of metering impulses.

(4) The assessor DA.-'The assessor is advanced by steps when the moment arrives for transmitting metering impulses, the stepping be ing continued until one of its wipers finds a zone contact characterized by a particular potential. On each step metering potential is applied over one of the speaking leads and in this way the calling subscribers meter is advanced a definite amount. The assessor serves moreover to register the small units of time. It is under the in fluence of a five or ten seconds contact and registers these time impulses until a larger interval of time, namely a minute, has elapsed. The minute units are then taken up by the time switch DZ as previously mentioned.

The mode of operation of the devices shown will now be described in detail.

Setting the zone characterizing devices.The seizure of the repeater takes place over the clead in which is disposed relay 0. Relay C is energized. Relay C closes contact 310 and thereby completes the following circuit: earth, contact 3|c, 25k, 2st, ZIww (rotary off-normal con tact operated when the two-motion switch is in its operated position) 2970 and 3012, wiper dg5 in the rest position, winding I of relay E, battery and earth. In this circuit relay E energizes and by closing its contact l25e connects the impulsing contact l28a to the magnet of the rotary switch DG. When now a numerical impulse train is transmitted by the calling station relay A is energized impulsively in' the following circuit by the impulsive application of earth to the upper speaking lead in the preceding connecting device: earth in the preceding connecting device. upper speaking lead, contact 69, winding I of relay A, battery and earth. Through the impulsive closing and opening of contacts iiliia and 16a earth is connected to the upper speaking lead on each impulse so that impulses are transmitted to the subsequent connecting devices over contact lll'ls corresponding to the impulses received and these serve to set these connecting devices. Through the impulsive closing of contact Ed the following circuit is completed for relay V: earth, battery, windings I and II of relay V, contact 5a and earth. When it energizes for the first time relay V closes contact 4v and thus short-circuits its winding II. It is thereby made slow-to-release and this suifices to hold up the contacts of relay V during the individual impulse trains. The rotary switch DG is now set by the impulsive closing of contact 1280., the magnet being operated over the following circuit: earth, contacts l597c, l28a, l2'isl and I256, the magnet of the rotary switch DG, battery and earth. The wipers of the switch DG are thus brought to a particular contact. Although wiper dg5 has left its rest position relay E remains operated throughout the impulse train in the following circuit: earth, contacts I510, I561), l55e and l54m, winding III of relay E. battery and earth.

If the zone is determined merely by the first numerical impulse train operating on the repeater the wiper dgZ stands on one of the contacts l to 5, l to 9 which is connected directly to one of the zone contacts ZoI to ZoV. If in particular cases the zone is determined by two impulse trains operating on the repeater a further setting of the rotary switch takes place in accordance with the second impulse train received. -The necessary requirement for this is that the first impulse train shall have brought the wipers of the rotary switch into position 6. After relay V has released on account of the prolonged opening of contact 5a after the impulse train comprising six impulses the following circuit is established over wiper dg5: earth, contacts 3lc, 257e, 26t, Z'lww, 29k and 3012, wiper (195 in position 5, windings III of relays T and Q, battery and earth, and winding I of relay 0, battery and earth. After the first impulse train the locking circuit for winding III of relay E is broken by the opening of contact I561) so that rela 1 E releases. Since, however, relay T has been energized in the circuit just described the impulse train which now follows is trans mitted to the magnet of the rotary switch DG over contact IZSt, while an undesired setting of the vertical magnet I-IH of the two-motion switch which was connected up when contact |24e closed is prevented by the opening of contact I 221i. The second impulse train is thus trans mitted to the magnet of the rotary switch DG over the following path: earth, contacts I59k, iZBa, I213! and [2615, the magnet of the rotary switch DG, battery and earth. At the end of this impulse train relay T releases again, this being a slow-release on account of the construction of the relay. Relay Q also remains up until after the end of the impulse train and also until the end of its natural release period, over the circuit: earth, contact 9a or lilo, lq, winding II of relay Q, battery and earth. Wiper dgZ is disconnected by contact 4415 and wiper dg3 is connected up through the closing of contacts Hi and 461 The zone contact is thus reached in the present case over wiper dg3 whose contacts are connected to the zone contacts ZoI to ZoV in a particular manner.

If the zone is not to be determined until the third impulse train operating on the repeater has been transmitted the rotary switch DG is brought to position 0 by the first impulse train operating upon it, i. e., the impulse train comprises ten impulses. In this case relays T and Q cannot energize. As already mentioned relay E releases a short time after the termination of the first impulse train (through the opening of contact i561. Contact l25e is thereby opened and the magnet of the rotary switch DG is disconnected and the vertical magnet H of the two-motion switch is connected up by the closing of contact I2 4 e, The second, impulse train operating on the repeater is thus repeated to the vertical magnet HH over the following circuit: earth, contacts l59lc, l28a, l21sl, 124e, IZZt, ll9u, IZOww (off-normal contact which is opened after the first rotary step of the two-motion switch) vertical magnet I-II-I, battery and earth. The wipers of the two-motion switch, of which only the two wipers full and hdZ are shown, are thus raised to a particular level. The contact field of the two-motion switch is indicated by dotted squares adjacent the wipers hdi and M12 for the sake of simplicity. Since the oii-normal contact 22lck is closed after the first vertical step of the two-motion switch the following circuit is set up when relay V releases: earth, battery, winding I of relay U, contacts llc, l8g, 2w, 22kk, Z'l'ww (rotary off-normal contact of the two-motion switch opened after the latter has taken the first rotary step), 262?, 25k, 3lc and earth. In this circuit relay U energizes. When now the third impulse train is received relay V is energized throughout this impulse train. Consequently contact 201) is closed thereby completing a locking circuit for relay U: earth, contact ISu, 20v, lBg, and He, winding I of relay U, battery and earth. During this impulse train, contact H911 is opened so that the vertical magnet I-II-I is disconnected and contact H811. is closed thereby switching in the rotary magnet DD of the two-motion switch. The third impulse train operating on the repeater accordingly operates the rotary magnet of the two-motion switch, this taking place over the following circuit: earth, contacts l597c, l28a, I21sl, I246, I222? and Ba, rotary magnet DD, battery and. earth. In the level to which the switch has been set the wipers are accordingly brought to a particular contact. On the termination of the impulse train relay V releases and releases relay- U by opening contact 2011-. The contacts of the two-motion switch are wired to the zone contacts ZoI to 20V in a particular way.

According to the embodiment it is also possible to determine the zone only after four impulse trains have operated on the repeater. If, for example, the first impulse train operating on the repeater comprises ten impulses, wiper 1192 is brought to position In., If then the twomotion switch is stepped to the sixth level and then set on the fourth contact in the sixth level the wipers hdl, hd2, stand on a line characterized by the number 64. After relay V releases after the third impulse train operating on the repeater the following circuit is completed: earth, battery, winding I of relay Q, line 64, wiper hdl, contact 42a (relay U remains up after relay V has released because it is made slow-torelease to a certain extent through the shortcircuiting of its winding II), contact dllq, contact l0, wiper c192. contacts 3814, Mt, 3912, 31c and earth. Relay Q opens its contact Mlq, breaks the circuit just mentioned and closes contact 48q, whereby the following locking circuit is established for relay Q independently of the contacts of relay U, over wiper hd2: earth, battery, Winding I of relay Q, line 64, wiper hdZ, contacts 48: Ht, 391) and 310 and earth. Relay Q closes its contact l2lq whereby the next impulse train is also transmitted to the rotary ma net DD of the two-motion switch in spite of contact H814 being open: earth, contacts l59k, IZBa, l2lsl, I24 l22t and l2lq, magnet DD of the two-motion switch, battery and earth. During this impulse train relay Q holds up over its winding II in a circuit which has'already been set out. The characterization of the zone (setting on a particular zone contact) now takes place over wiper hdZ of the two-motion switch whose contacts are connected to the zone contacts 201 to 20V in a particular'way.

The characterization of the zone by four impulses trains operating onthe repeater can be efiected in an alternative manner. If, for example, impulse trains corresponding to the number 066 are sent into the repeater wiper hdl of the two-motion switch will stand on line 56 so that after the release of relay U and during the release period of relay U the following circuit is closed: earth, battery, inding I of relay T, line 66, wiper hdl, contacts 42a and lllq, wiper dg2, contacts 38a, Mt, 39v and Zlc and earth. In this circuit relay T energizes and by opening its contact Mt disconnects wipers hell and M12 of the two-motion switch and by clos ing contact 45f connects wiper dot of the rotary switch DG. The following locking circuit is established for relay T: earth, battery, winding I of relay T, level contact 49dk6 (closed when the two-motion switch is set on level 6), contact Ill, wiper dg i, contacts -i'lq, 45 39v and 3|c and earth. During the impulse train which now follows relay T holds up over its winding II in a circuit which has previously been described. The fourth impulse train received by the repeater is now also taken up by the rotary switch DG whose magnet is operated by contact l26i: earth, contacts IESk, l28a, l2'ls i and 126i, the magnet of the rotary switch DG, battery and earth. The characterizing of the zone now takes place over wiper 194 of the rotary switch DG over a contact of the latter which is directly connected to one of the zone contacts ZOI to 20V.

ZONE CONTROL For each of the numerical impulse trains operating on the repeater the zone control sets in automatically: i. e., switching operations are pro- (a) Zone control after the first impulse train operating on the repeater- The rotary switch DG is set so that its wipers do not rest on contacts 6 or Ill. By the setting of the rotary switch DG in accordance with another digit the zone is characterized solely by this first impulse train operating on the repeater. After the release of relay V the following circuit v for relay K is set up: earth, battery, winding I of relay K, one of the contacts 'l9k, 80k, Slk, 82k or ask, one of the zone contacts ZOI to ZoV, wiper 11912, in a position other than 6 or HI, contacts 368, Mt, 38v, and 3H: and earth. Relay K energizes and by opening its contact I59k brings the influencing of the zone determining devices by numerical impulse trains to an end.

Relay K locks up over the following circuit throughout the duration of the call: earth, battery, winding II of relay K, contacts 24k and Mo and earth. Contact 31k maintains the earth connected over contact Elc connected to wiper dot and the corresponding zone contact.

It may be mentioned that relay X is energized over the following circuit during each impulse train: earth, contacts 61c, 69c and 68p,

windings II and I of relay X, contact 65h, re-

sistance Wil l, battery and earth. Relay X closes its contact 6611: and thereby short-circuits its winding I so that after relay V has released and contact 6911 has opened it retains its contacts in the operated position for a short time. After the release of relay V and the closing of con tact 3912 it is possible for relay K to energize. If, however, this isnot possible on account of the presenceof a fault in the zone lead relay S energizes after relay X has released, in the following circuit: earth, battery, the-winding of relay S, contacts q and 34x, wiper dgl in a position other than 0, 5 or II], contacts 261?, 25k and 3lc and earth. If, therefore, the zone circuit cannot be exerted'in-a positive sense relay S energizes and by opening its contacts I015 and [68s disconnects the stepping leads and renders the further setting of connecting 'devices impossible. Relay SI also energizes and at contact I218! disconnects contact 128a. Through the closing of contact lfiis a busy signal is applied to windings II of relays A and F and is induced in the windings -I of these relays which are connected to the speaking leads and is thus transmitted to the calling subscriber. Winding I of relay F is connected over contact 3g and a condenser to the lower speaking lead and winding I of relay A to the upper speaking lead over contact to. The relays S and SI hold up in the circuit set out above until the calling subscriber replaces his receiver on account of the prolonged busy signal and transmits the signal for the release of the devices which have been set.

(1)) Zone control after two impulse trains have operated on the repeater In this case' the calling subscriber transmits an impulse train corresponding to the number 6 as the first impulse train. Wiper (195 is thus set on contact 6, over-which relays T and Q are energized over their windings III and relay 0 over its winding I after relay V has released. After this impulse train relay K cannot yet energize because contact. 6 of the rotary switch is not connected to any of the zone contac-ts 201 to -ZOV. Similarly the blocking relay S cannot energize because this is disconnected by contact 35g. Thus although the zone control relay K cannot energize after the first impulse train the blocking of the connection by relay S is also prevented. Only when the rotary switch DG has received a further impulse train is the following circuit set up for relay K: earth, battery, winding I ofrelay K, one of the contacts 19k: to 83k, one of the zone contacts ZoI to ZOV, a contact in the contact bank associated with wiper dg3, wiper dg3, contacts 461 st, 3912 and Bio and earth. When relay K energizes in this circuit, contact lZlc and the two relays Q and T remain energized in the following circuit until the end of the call: earth, contacts 80, 12k and Mq, winding II of relay Qand contact l5t, winding II of relay T, battery and earth. After relay K has energized and locked up at contact .24k a particular zone contact is connected to earth over contact 3lc by way of wiper (Z93 and contacts 45t and 46g.

If, however, relay K is not able toenergize in the above circuit on account of a break in the zone lead or because a false second number has been dialled whereby wiper dg3 is set on a contact which is not connected to a zone contact, no locking circuit is set up for relays Q and T so that after relay X has released the following circuit is established for the blocking relay S: earth, battery, the winding of relay S,

contacts 35q and 34x, wiper rlgl, contacts 2% h connected to the other contacts of this contact bank. As already described relay was energized over its winding I when wiper (105 was set on contact 6. Relay 0 looks up in the following circuit: earth, contacts to and I370, winding II of relay 0, contact 230, battery and earth. This locking circuit remains in existence until the clearing signal is given if the zone controlling relay K cannot energize. In this case the following circuit is closed for the blocking relay S:

earth, battery, winding of relay S, contacts 351! and 36x, wiper 1191 in position I0, contacts 330,

26t and 25k, 3Ic and earth.

(0) Zone control after the third impulse train operating on the repeater After the rotary switch DG has been set on the th contact the wipers of the two-motion switch stand on some line which is not especially indicated (but not on lines 64 and 66) after the next two impulse trains. After relay V has released at the end of the third impulse train opcrating on the repeater, the circuit for the zone control relay K is set up over wiper hall and wiper (192 in position III, the circuit being set up over contact 3811. of relay U which maintains it contacts operated after the release of relay V. Relay K locks up as before at contact 2479 throughout the duration of the call and at contacts 31k and Mia maintains the connection of earth to the corresponding zone contact.

If for the reasons mentioned above the circuit for relay K is not completed the blocking relay S and relay SI become energized in the following circuit after relay K has released; earth, battery, the windings of relays S and SI, contacts 35q, 34m and 28ww (rotary off-normal contact of the two-motion switch which is closed when the switch takes its rotary step). contacts 251, 25k; and Mo and earth. Relay S initiates the operations already described for preventing the further establishment of the call and for communicating a busy signal to the calling subscriber, while relay SI prevents the zone characterizing devices from being influenced by further numerical impulse trains at contact IZIsI.

(d) Zone control after the fourth impulse train operating on the repeater If the two-motion switch is set on line 64 relay Q is energised as already stated and this disconnects wiper hill of the two-motion switch at contact 40g and connects up wiper hcl2 by closing contact 48g. During the fourth impulse train operating on the repeater, which is also received by the rotary magnet DD, of the twomotion switch, relay Q remains operated over its winding II for some time after relay V has released at the end of the fourth impulse train. Thus the wipers of the two-motion switch stand on a particular line (not shown) which is connected to one of the zone contacts ZOI to ZoV.

During the release period of relay Q the zone control relay K is tested as to its ability to energize, in the following circuit: earth, battery, winding I of relay K, one of the contacts 19k, to 8310, one of the zone contacts ZOI to ZOV, wiper hd2 of the two-motion switch, contacts 48q, Mt, 39v and 3Ic and earth. The blocking relay S is not able to energize because contact 2570 is open. If, however, relay K does not energize within the release period of relays Q and X a circuit which may be seen from the drawing is once more set up for the blocking relay S.

If the two-motion switch is brought by the third impulse train operating on the repeater to line 66, relay T is operated as already explained and this holds up over its winding II during the following fourth impulse train until the end of this train, when relay V releases. At contact 44t the wipers of the two-motion switch are disconnected and wiper (Z94 of the rotary switch DG- is connected up at contact St. The wipers of the rotary switch DG are stepped further by the fourth impulse train, so that wiper (Z04 is set on a contact which is connected to one of the zone contacts ZoI to V. When relay V releases at. theend of the fourth impulse train the zone control relay K is tested as to its ability to energize in the following circuit: earth, battery, winding I of relay K, one of the contacts 19k to 8370, one of the zone contacts ZoI to ZoV,

wiper do l set on a particular contact, contactsclq, 4st, 39v and 3Ic and earth. If relayK cannot energize during the release period of relay X, the circuit for the blocking relay S and forrelay SI is again closed.

The wanted subscriber replies When the wanted party replies after all the ing lead in one of the succeeding connecting devices. Thus the following circuit is established: earth, battery in the succeeding connecting devices, the lower speaking lead, contacts I08s and. H2112, winding II of relay Y2, contacts Hi9 and Itlllc and earth. Relay Y2 which energizes in this circuit at contact H2112, breaks the previously existing short-circuit for winding I of relay G so that this relay can energize in the above-mentioned circuit. Relay G closes its contact II Ilg and thereby locks up over earth, con- 5: tacts Ill9k and H09, winding II of relay G, battery and earth. Through the opening of contact III g it breaks the above-mentioned circuit. Through the closing of contact I349 the following circuit is closed for the switch DA which responds to the small units of time of five or ten seconds: earth, battery, the magnet of switch DA, contacts I290, I358, I31m, and I396, the fiveseconds contact and earth. Relay E was operated over its winding III in the following circuit: earth, contact I5Ik, wiper da3 of the assessor in position 0--I, winding III of relay E,

battery and earth. The assessor consequently receives five seconds impulses and steps its wipers at intervals of five seconds. When wiper (1113 ,has left contacts I] and I relay E releases and by closing its contact I38e switches on a 10 seconds contact in place of the five seconds contact so that now the assessor is advanced at intervals of 10 seconds.

.III

When after the expiry of"75.

'III

-' contacts cuit for relay YI.

about a minute the wipers of the assessor reach contact 9 the assessor commences to pass automatically to the zero position. This occurs in the following manner: When wiper daI reaches the ninth contact the following circuit is completed: earth, battery, magnet DA of the assessor, contact I290, contact 9, wiper daI, the winding of relay R, contacts I4Eu, I4'Ih, I49y2 and earth. Relay R which energizes in this circuit closes its contact I9r and thus completes the following circuit for relay U: earth, contact I91, winding II and I of relay U, battery and earth. By the opening of contact I46u the above circuit in which magnet DA and relay R were energized is broken. The assessor magnet DA and also relay R release, so that the circuit for relay U at contact I91 is broken again. Magnet DA and relay R are again operated by the closing of contact I46u. The interaction between relays U and R continues until wiper daI has left its last contact and has passed into the rest position. The following circuit for the magnet DZ was closed over wiper (M3 in position 9: earth, contact I5Ik, wiper da3, position 9, contact I52x, magnet DZ of the time switch, battery and earth. The time switch accordingly advances its wipers from the rest position to the first contact. The following circuit then obtains for relay M: earth, battery, winding I of relay M, contact I, wiper d2! of the time switch, contacts H09 and I99]; and earth. Relay M holds up throughout the duration of the call in the following locking circuit: earth, battery, winding II of relay M, contacts IIm, I2k and 8c and earth. When the circuit already mentioned for winding III of reiay E is closed again when wiper da3 moves into the rest position the 10 seconds contact remains connected to the assessor magnet because of the closed contact I3Sm. When now after expiry of the second minute the wipers of the assessor pass to position I the play between relay R and U sets in once more, relay R being energized together with the assessor magnet in the following circuit: earth, contacts I49y2, M171. and Him, the winding of relay R, wiper dal in position 1, contacts I32m and I290, magnet DA of the assessor, battery and earth. The assessor is thus switched back to its normal position. On passing through position 9 the circuit previously mentioned for the time switch DZ was again closed so that the wipers of the time switch are set at contact 2. The third minute of the conversation now commences. When the switch passes to position 5 under the influence of the 10 seconds contact relay Z energizes in the following circuit: earth, battery, the winding of relay Z, contact l30y4, contact 5, wiper daI, the winding of relay R, contact I4'Su, I4'Ih and I49y2 and earth. Relay Z closes its contact I022 and thereby completes the following circuit for relay Y3: earth, contacts I99lc, IIlIg and I022, winding II of relay Y3, battery and earth. Relay Y3 closes its contact IIlIy3 and thereby completes the following circuit for relay YI: earth, I99k, IIllg, lull/3, winding I of relay YI, battery and earth. RelayYI causes relay Y2 to energize over its winding I by closing contact IIlDyI. This battery relay by closing its contact 98112 switches on relay Y4 over earth, contacts W970, H09 and 98y2, the winding of relay Y4, resistance WiI3, batttery and earth. The opening of contacts ISM/4 and 962/4 disconnects the circuit of relay Z. Relay Z at contact l02z opens Y3. Contact IIIIy3 breaks the cir- Relay YI disconnects the time switch pass to position 3.

circuit of relay Y2 atcontact [001/1 so that the latter relay deenergizes. Relay Y2 closes its con- ,tact 99M and thereby short-circuits the winding'of relay Y4 so that in spite of its locking contactQ'IM, relay Y4 is caused to deenergize. For the period between the operation of relay Z and the release of relay Y4 a warning si nal is transmitted to the calling subscriber shortly before the expiry of the third minute of the conversation, in that the following circuit is established: buzzer Su, contact I642 or I65y4, wiper d22 set on contact 2, contact I62s, winding II of relays A and F, wiper 01103 in one of the positions 5 and 8, contact I5Ilc and earth. The buzzer tone is transmitted inductively to windings I of relays I and A in the speaking leads and hence to the calling subscriber. Winding I of relay A is now connected over contacts 1g and a condenser to the lower speaking lead and winding I of relay F to the upper speaking lead over a condenser and contact 59. During the release period of relay Y4 which was short-circuited after the release of relay Y2 the assessor is advanced from. position 5 to position 6: earth, battery, magnet DA of the assessor, contacts I290 and I.3Iy4, wiper (MI in position 5, 'the winding of relay R (which does not energize in this circult) contacts I46u, M171. and M9212 and earth. After a further 10 seconds the wipers of the assessor are brought. to contact I from which they are advanced to the zero position by the aid of the relay interrupter RU in the manner already described. When wiper da3 passes through position 9 the circuit for the time switching relay DZ is again closed so that the wipers of the The following circuit for relay X is now completed over wiper o'el of the time switch: earth, contacts I09Ic and H99, wiper dz in position -3, contacts He and 68p, windings II and I of relay X,'contact 65h, resistance WiI I, battery and earth. When the assessor moved into position I3 the following circuit is set. up for relay I-I: earth, battery, winding I of relay I-I, contact I593), wiper (m3 of the assessor in position I3, contact I5Iic and earth. Relay I-I locks up over earth, battery, winding II of relay H, contacts 9Ih, 921), M09 and I097c and earth. Relay H opens contacts 85h andthus breaks the circuit just described for relay X which accordingly releases.

Metering for the first unit of time lead over a series of resistance and choke-coils: earth, battery, resistance WiII, choke-coil DT3, contact 598I, resistances Wzfl, Wi'I, WiG, W 5, W14, W13, WM and. WiI, chokecoil DTI, lower speaking lead. On account of the various resistances and the choke-coils the application of the metering potential by com tact 64h to the lower speaking lead is damped so that the subscriber engaged in conversation is disturbed as little as possible. Through the closing of contact Ihthe assessor magnet DA receives a stepping impulse over the following path: earth, battery, assessor magnet DA, contacts I290, I349, IMIII, I42p, I44y4, I45h, I49y2 and earth. The assessor magnet posseses acontact 89da which is now closed and by means of which the following circuit is established:

contact 54h.

earth, battery, winding II of relay Y3, contacts The circuits are as follows: earth, contacts l09x, H09, and H3 W3, winding I of relay Yl, battery and earth and: earth, contacts H1916, my, 96214, 95, 13, the winding of relay Z, battery and earth. By closing its contact lllfiyl relay YI energizes relay Y2, By the closing of contact 98y2 relay Y4 is energized and thus locks up by closing contact fill/4. Through the opening of contact 96114 the above-mentioned circuit for relay Z is broken and this consequently releases. After relay Z relay Y3 releases, the winding 11 of this relay having been disconnected meanwhile at contact llgda. After relay Y3 relay Yl releases, after relay Yl relay Y2 and after relay Y2 relay Y4, all being short-circuited.

The above-mentioned operations are now repeated because the circuit for the assessor magnet DA which was opened at contact Mflyd when relay Y4 energized is completed again at this contact after relay Yl has released. The assessor magnet is advanced a further step and by closing its contact 89cm causes the switching on of relays Y3, X, Yl, Y2 and Y4 in the manner described above.

- Each time these relays perform this set of operations a metering impulse passes over the'lower speaking lead to the metering relay in the preceding connecting device in that the individual resistance Wz'i to Wz'S are short-circuited in succession by the contacts of the above mentioned relays and on the subsequent releaseof the relays are switched in again in the succession Wil to W2'8. Each of said relays possess contacts which draw up and release at moments displaced from one another in time so that for example contact 50y! is closed before contacts 5ly2, 52y! before 54yl, 55113 before 563 3, and 5'52 before 582. Thus the above-mentioned contacts are closed in succession and in this Way the metering potential connected to the lower speaking lead is gradually increased to an extent which suflices to energize the metering relay connected to the lower speaking lead in the-preceding connecting device. On the subsequent release of these relays at the end of each metering impulse, the resistances Wil to W18 are gradually switched in and the current over the lower speaking lead is gradually reduced again so that the metering relay in the preceding connecting device can release. On account of the gradual switching in and switching out of the resistances and by the gradual application and disconnection of metering battery subscribers engaged in conversation are disturbed as little as possible. For each step of the assessor one metering impulse is transmitted over the lower speaking lead. The number of metering impulses to be transmitted at the end of every three minutes interval is determined by the setting of the zone characterizing devices, 1. e., by the setting of the rotary switch DG and of the two-motion switch I-II-I/DD. Over the wipers of these switches a particular zone contact ZoI to ZoV is connected to earth as previously described. As has been mentioned, relay H, which determines the moment for commencing metering, is energized when wiper daS passes through position l3. The transmission of metering impulses accordingly only commence when the Wipers of the assessor have reached contact l4. If, for example, the zone characterizing devices connect the zone contact 201 to earth, as many metering impulses are transmitted as there are steps necessary in order to bring wiper da2 from position I4 to that position to which the zone contact 201 is connected. In theexample shown this wouldbe two impulses. After the transmission of two metering impulses the following circuit obtains during the release period of relay Y4 which is the last of the relay chain to deenergize: earth on zone contact ZoI applied by the zone characterizing devices, wiper da2 on contact l6 contacts 1511i, Nye and I lit, the winding of relay P, battery and earth. Relay P at contact M217 breaks the stepping circuit for the assessor magnet DA which was closed during the transmission of metering impulses. At contact 9473 it locks up over earth, battery, the winding of relay P, contact 12c, resistance Wii2, contacts 94p, (66g and N970 and earth. By the opening of contact 92p the above-mentioned locking circuit for relay H which determines the commencement of metering is broken so that this relay releases. The result of this is that contact M'lh. is closed and consequently a circuit is completed which circuit contains the relay R and the assessor magnet DA. The interaction of relays R. and U by means of which the assessor is restored to normal now sets in once more. When the assessor has reached its normal position relay E is ope-rated again over winding 3 and by opening contact 122 breaks the locking circuit for relay P and thus causes this to release. This terminates the metering for the first 3 minutes interval. switch the assessor magnet DA is now stepped around again and the second 3 minutes interval commences, and after the expiry of 6 minutes the second transmission of two metering impulses takes place in the manor described.

It may be mentioned that after the lapse of each interval or 3 minutes, i. e., when the wipers of the time switch DZ are set in positions 3, 6, 9, etc., relay E is held energized over its winding 3 during the following time unit of 1 minute. So long as wiper da3 stands on contacts and I relay E is energized in a circuit which has been mentioned earlier. In positions 2 to 4 of the assessor DA, E is energized as follows: earth, contact-s I5Ik, wiper (M3 on

contact

2, 3 or 5 over contacts 0, 3, 6, 9, l2 of the bank associated with wiper (Z23, contact "56m, winding III of relay E, battery and earth. In positions 5 and 6 of wiper da3 relay E is held energized over the following circuit: earth, contact l5llc, wiper da on contact 5 or 6, wiper 0123 on one of the contacts 3, 6, 9, etc., contact Hillm, winding III of relay E, battery and earth. By this means so long as wiper clzl stands on one of the contacts 3, i3, 9, etc., any undesired operation of relay X at contact Tie and any consequent premature energizing of the relay H which promotes metering at contact I503: is prevented.

It can be seen directly from the drawings that if another zone contact is connected to earth over the zone characterizing devices, a different number of metering impulses is transmitted. If, for

Under the influence of the 10 secondexample, the zone contact ZoII were connected to earth then 6 metering impulses would be transmitted. after each 3 minute interval in the case of such a call. If the zone contact ZoIII were connected up 10 metering impulses would be transmitted, in the case of zone contact ZoIV 14, and in the case of zone contact 20V 18 impulses for every 3 minute interval.

When the calling subscriber hangs up on finishing his conversation, battery potential is applied to the upper speaking lead in the preceding connecting deviceso that the following circuit is set up for relay F in the repeater: earth, battery in the preceding connection device, upper speaking lead, contacts 59*, Ma, winding I of relay F and earth. Relay F closes its contact if and thereby completes the following circuit for relay X: earth, contacts T07, 6810, windings i2 andi of relay X, contacts 65h, resistance Wil I, battery and earth. Relay X closes its contact thereby brings the assessor magnet DA under the influence of the relay interrupter. With the aid of relays R and U the assessor is advanced until, in position I3 a circuit which has already been given for relay H is set up over wiper daI-l. Relay H locks up at contact SH]. and by opening contact 54711. interrupts the interaction between relays U and R. The assessor'magnet DA receives a stepping impulse over the following path through the closing of contact MEh: earth, contacts I49y2, I457, i l ly l, M21), I lIr (relay X was deenergized by relay H at contact 65h), I349, I290, assessor magnet DA, battery and earth. The assessor magnet operates its contact 89da so that the following circuit is set up: earth, battery, winding II of relay Yi, winding I of relay SI, contacts 88y3, 87 885m, 981;, 9Ih, 92p, I109, I09k and earth. In this circuit relays YI and SI energize. Relay SI locks up over: earth, battery, winding 11 of relay SI, contacts 32s'l, 3Ic, and earth. Through the opening of contact 59sI the resistance chain WiI-WiB is disconnected and by the closing of contact SilsI the full strength of the metering battery is applied directly; while eliminating the resistance chain, to the lower speaking lead: earth, battery, resistance WiI I, contact 64h, choke-coil Dr3, contacts BilsI, 6Iy4 and 62yi, choke-coil Drl, and the lower speaking lead so that the metering relay in the preceding connecting device will immediately energize and cause the meter to be advanced. Relay YI closes contact Iflllyl thereby switching on winding I of relay Y2. At contact 98y2 relay Y2 switches on relay Y4 which looks up by closing contact 91114. Relay Y4 opens contact I My I and thereby breaks the circuit for the assessor magnet DA. By the opening of contact 89da the circuit over which relays YI and SI were energized is broken so that relay Y releases. Relay SI holds up over its winding II. At contact IIJByI relay YI breaks the circuit for relay Y2 so that contact 99112 is closed and relay Y4 is short-circuited. The stepping circuit for the assessor magnet is thus closed again at contact IMy I so that the cycle of operations is started afresh. During each cycle the metering impulse is started up by the closing of contact 82g! and terminated by the opening of contact El 4. In this way a corresponding number of impulses is transmitted at a relatively more rapid rate. Thus on metering at the end of the call only the relays YI, Y2 and Y4 of the group Z, Yi-YI are used. The transmission of metering impulses is terminated when wiper daZ passes into a position which is connected to earth over one of the zone contacts ZoI to ZoV and over the zone characterizing devices, as has already been explained in detail. The metering terminating relay P disconnects earth from the upper speaking lead by opening its contact ip, this being the signal that the preceding connecting device is released. Relay F in the repeater continues to hold up for the moment in a local circuit: earth, battery, resistance Wis, contacts I f, and 2p, winding I of relay F and earth. Relay F holds up until relay P releases after the end of the metering and when the repeater is released. Through the disconnection of earth from the upper speaking lead the c-lead in the preceding connecting de- M-ila: and I vice is broken so that relay C in the repeater releases.

Restoration of the switches in the repeater In this circuit in addition to 10 The time switch is then brought to normal. ,15

The following circuit obtains: earth, contacts M9112, I4Ih, Mtu, winding of relay R; contact I580, wiper dot, in the rest position, wiperdz l in the working position, magnet DZ of the time switch, battery and earth. The time switch is .20

stepped by the relay interrupter RU until it has reached the normal position. Thereupon the two-motion switch is restored to normal. The following circuit obtains: earth, contacts HEE /2, Ifllh and Mia, winding of relay R, contact I580, wiper (296, in the rest position, wiper de l in the rest position, off-normal contact IIIlclc (closed after the first vertical step of the two-motion switch), rotary magnet DD of the two-motion switch, battery and earth.

The rotary magnet is stepped until the rest position is reached under the influence of the relay set U/R. Y

Finally the assessor is restored. The following circuit obtains: earth, contacts M9112, I4Ih,

M5141, winding of relayR, contact i580, wiper (96 in the rest position, wiper dad in the rest position, off-normal contact IIBkIc, (closed when the two-motion switch is in the normal position) wiper dad in the working position, magnet DA of the assessor, battery, earth; When the assessor has. reached the normal position under the influence of the relay set U /R this circuit is broken at wiper daA.

Through the release of relay C the other switching devices are also restored to normal. The locking circuit for relay M is broken at contact 8c'and the locking circuit for relays SI and K at contact 3Ic. Similarly at contact 80 the locking circuit for relays Q and T is broken. provided these have been energized. The locking circuit for relay P is broken at contact limit, At the same time, at this. contact, the locking circuit for relay G is broken. After relay P has released the locking circuit of relay F is broken at contact 2p.

The calling subscriber hangs up during metering In the event of the calling subscriber replacing his receiver when a metering impulse has just been produced by the relay chain Z, YIY4, the transfer to rapid metering cannot take place before the termination of this metering impulse since the first impulse of the more rapid succession can only be transmitted when the first and These relays cannot energize, however, because contact 88113 of relay Y3 which only energizes, however, in the case of metering during a call is opened. This releases when after relay Y4 has energised the circuit for relay Z is broken by the opening of contact 30114 and the locking circuit for relay Y4 is broken by contact 8911a. When the second metering impulse is terminated, that is when relay Y4 has released on account of the short-circuit established at contact 99112 the assessor magnet energizes over contact M4 14 so that now relays SI and YI become energized when contact 8911a closes. and thus commences the first impulse of the more rapid succession. The further operations then take place in the manner described above.

What is claimed is:

1. In an automatic switching system, means for extending connections to a plurality of zones, zone determining means in said system operated in accordance with the zone to whicha connec tion is extended for determining the particular metering impulses to be transmitted for a connection, and blocking means operated after the zone determining means has been operated for preventing the further extension of the connection unless said zone determining means is operated to a proper position to determine said impulses.

2, An automatic switching system as claimed in claim 1, in which said blocking means is also efiective for preventing any further influencing of the zone determining means.

3. An automatic switching system as claimed in claim 1, in which the blocking means includes two relays, one of said relays operated to prevent the further extension of a connection, and the other of said relays is affected by said zone determining means to either prevent or allow the operating of said one relay.

4. In an automatic switching system, means for extending connections to a plurality of zones, zone determining means in said system having a plurality of contacts each associated with the transmission of particular metering impulses in accordance with the zone to which av connection is extended, blocking means for preventing the further extension of a connection, and other means operated through any one of said contacts to render said blocking means ineffective.

5. An automatic switching system as claimed in claim 4, normally closed contacts associated with said other means, and means including said closed contacts for rendering said blocking means efiective.

6. An automatic switching system as claimed in claim 4, in which the operation of either of said blocking or other means is effective to prevent further influencing of the zone determining means.

7. An automatic switching system as claimed in claim 1, a test relay in said zone determining means, said relay tested as to its ability to operate after the determination of said impulses and said blocking means thereafter rendered effective or ineffective in dependence upon said relay.

8. In an automatic switching system, means responsive to impulse trains for extending connections to a plurality of zones, zone determining means in said system for determining, in accordance with the zone to which a connection is extended, the particular metering impulses to be transmitted for that connection, devices in said determining means responsive to said impulse trains and testing means associated therewith rendered effective responsive to a particular setting of one of the devices for determining whether the connection may be completed.

9. An automatic switching system as claimed in claim 8, means affected by said testing means for preventing the further extension of a connection, and other means associated therewith for rendering the same ineffective at times when one of said devices does not have a particular setting.

10. An automatic switching system as claimed in claim 8, wherein a fault in said device having a particular setting renders said testing means ineffective and prevents further extension of a connection.

11. In an automatic switching system, means for extending connections to a plurality of zones, a zone determining device in said system operated in accordance with the zone to which a connection is extended for determining the particular metering impulses to be transmitted thereto, said device including a circuit for maintaining potential on said means through a series of inductances and a series of relays each associated with certain of said inductances, and means for operating said relays in sequence responsive to one of said metering impulses to transmit im pulses by varying the effective inductance of said circuit.

12. In a metering'arrangement associated with means responsive to impulses transmitted for extending connections, a plurality of control leads for determining a number of metering impulses to be transmitted periodically over a connection, a stepping switch, having access through certain of the bank contacts thereof to said control leads, responsive to a particular impulse train for rendering a particular control lead effective, other contacts of said switch engaged simultaneously with said certain contacts, a relay operative in a circuit including one of said other contacts for preventing further extension of a connection on termination of a particular impulse train, and another relay associated with said control leads operated in a circuit including said particular control lead to render said first relay ineiiective.

13. In a metering arrangement associated with means responsive to a series of impulse trains for extending connections, a plurality of control leads for determining a number of metering impulses to be transmitted periodically over a connection, stepping switches, having access through certain of their bank contacts to said control leads, one of said switches responsive to a particular impulse train of the series for rendering a particular one of the control leads effective, other contacts of one of said switches rendered effective by certain impulse trains of the series, a relay operative in a circuit including one of said other contacts for preventing further extension of a connection on termination of a particular impulse train, and another relay, associated with said control leads, operated in a circuit including said particular control lead to render said first relay ineffective.

HANS J LURK.