US2293611A

US2293611A - Telephone system

Info

Publication number: US2293611A
Application number: US376961A
Authority: US
Inventors: Lloyd T Meeds
Original assignee: American Telephone and Telegraph Co Inc
Current assignee: AT&T Corp
Priority date: 1941-02-01
Filing date: 1941-02-01
Publication date: 1942-08-18
Anticipated expiration: 1959-08-18

Description

Aug. 18, 1942. L. 1'. MEEDS TELEPHONE SYSTEM Filed Feb. 1, 1941 9 Sheets-Sheet l 1% w\ N N \Q\ I] ews Q #9 6R 5 HI P flfi 8.?! MHU gin U 8% 2 mot mwt 5.0K h m but not Y0K N9 m ii 6Q mat GE QWNEGQQQ 6P lNVENTO/P LIME E 05 51 A T TORNEV Aug. 18, 1942. L. 'r. MEEDS 2,293,611

TELEPHONE SYSTEM Fil ed Feb. 1, 1941 9 Sheets-Sheet 2 FIG. 2

//V L. r M5505 W WT ATTORNEY Aug. 18, 1942. 1.. -r. MEEl DS 2,293,511

' TELEPHONE SYSTEM Filed Feb. 1, 1941 9 Sheets-Sheet 3 ATTOR g 18, 1942; L. 'r. MEEDS TELEPHONE SYSTEM 9 Sheets-Sheet 4 Filed Feb. 1, 1941 INVENTOR .L. T MEEDS ATTORNEY Aug. 18, 1942. L. T. MEEDQ TELEPHONE SYSTEM Filed Feb. 1, 1941 9 Sheets-Sheet 5 D0 oo /Nl ENTOR L. T M15505 4L ATTOR EV Aug. 18, 1942.

L.T.MEEDS TELEPHONE SYSTEM Filed Feb. 1, 1941 9 Sheets-Sheet 6 /NVENTO/? L. TMEEDS Aug. 18, 1942. 1... 'r. MEEDS TELEPHONE SYSTEM 9 Sheets-Sheet 7 Filed Feb. 1, 1941 INVENTOR L. 7. M51505 W, 7 7%? ATTORNEY Aug. 18, 1942. y L. T. MEEDS 2,293,611

TELEPHONE SYSTEM Filed Feb. 1, 1941 9 Sheets-Sheet 8 /NI/ENTOR L. 7'. ME E 05 A TTOR/VE V Aug. 18, 1942. L. T. MEEDS 2,293,611

TELEPHONE SYSTEM Filed Feb. 1, 1941 9 Sheets-Sheet 9 Q 0 a a & R [Q IHI- INVENTOR L. 71 MEEDS v MWMW ATTORNEY Patented Aug. 18, 1942 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Application February 1, 1941, Serial No. 376,961

15 Claims.

This invention relates to telephone systems and has for its object to facilitate the testing of automatic telephone exchanges particularly when newly installed,

The vast number of connections made during the installation of an automatic telephone exchange require a thorough test of every part of the exchange before placing it in service. However, satisfactory individual tests may not result in satisfactory operation under service conditions, since the trafiic load is a factor of great im portance in the ability of an ofiice to function.

In accordance with the present invention, means is provided to simulate service conditions by originating a large volume of calls over a group of lines and directing the calls to a variety of destinations in proportion to the expected service load.

By this means it becomes possible to determine whether the equipment will handle the expected maximum trafiic with the proper margin of safety from the standpoint of condition, quantity and distribution of the circuits involved.

In addition, the call originating means of the present invention supplements the special circuit test equipment by creating a condition of service under which the individual pieces of equipment must function.

A further advantage provided by this call originating means may be found in the training given the maintenance force in the handling of troubles which may arise or may be artificially produced.

Specifically the invention provides means for seizing a plurality of line terminals one at a time and originating a call thereover. After an interval the lines are successively connected to a plurality of dialing means which are arranged to transmit different designations over each line.

Subsequently, each set of line terminals is seized 4.

to simulate disconnection. Means is provided for determining the intervals between each seizure of given line terminals together with means for maintaining the intervals for all of the lines.

The means for seizing the line terminals com- L prises a plurality of rotary switches each of which has access to all of the lines. Manual means is provided for starting each switch, after which the switches advance in synchronism so that a different plurality of lines are acted on at each step.

The invention will be more clearly understood from a consideration of the following description in connection with the accompanying drawings, in which Figure 1 shows the switch which controls the dialing of the thousands and hundreds digits, and two sets of line terminals;

Fig. 2 shows a switch for dialing the tens and units digits as well as certain control relays;

Fig. 3 shows the code dialing switch;

Fig. 4 shows the line seizure controlling equipment;

Fig. 5 shows the switches which connect with the line terminals;

Fig. 6 shows the numerical dialing control relays;

Fig. 7 shows the relays which start the number dialing;

Fig. 8 shows the control keys;

Fig. 9 shows the I synchronizing relays; and

Fig. 10 shows the arrangement of Figs. 1 to 9.

This call originating circuit is particularly designed for testing the cross-bar type of telephone system such as disclosed in U. S. Patents No. 2,235,803, to W. W. Carpenter, March 18, 1941, and No. 2,232,371, to J. W. Dehn et al., February 18, 1941, but is equally applicable to other types of dial telephone systems.

Before starting the use of the call originator, fifty sets of originating line terminals are selected and connected with fifty sets of terminals such as terminals I03, HH and I20, l2l in the call originator. In addition, forty-four telephone designations are selected and the brushes of

switches

550, 560 and 510 are cross-connected to switches 359, I50 and 250 in accordance therewith. By spreading the lines selected over the originating equipment and selecting the designations to include a variety of office codes and number groups, as well as operator codes and unstand designations such as permanent signals, etc., a traffice load closely resembling the actual expected service load can be built up. For larger offices a plurality of these call originators may be used to create a suflicient load.

The test circuit consists essentially of five integral parts which function together as a single circuit unit. These five parts may be called 1. Dial tone seizure circuit.

2. Office code dialing circuit.

3. Thousands and hundreds digit dialing circuit.

4. Tens and units digit dialing circuit.

5. Line disconnect circuit.

Each of these five circuits connects with a pair of line terminals in succession and the interval between the connections of the five circuits with any single line is dete n d by a ,key which conthan the intermittent load which is produced by test circuits which originate a plurality of calls simultaneously and may conveniently supplement the use of the latter.

No means is provided in this circuit for checking the accuracy with which the connections are established. However, by connecting a condenser across the terminating line terminals corresponding to selected designations, to satisfythe marker, and preventing the operation of the intercept relays, of; the terminating'markers, every case of trouble will cause a record to be made by the trouble indicator. Since the" terminating trouble indicator gives the number called and identifies the marker, the sender and the incoming circuit involved; the large volume of calls given by the call originator quickly brings out any circuit failures likely to signal wrong numbers.

Dial tone seizure circuit Referring now to the detailed functioning of the circuit; the operation is started by operating start key 880. This key groundsconductors BM, 8112, and 833. Ground on conductor 81 completes the circuits of relays I02, 206, and 300 which, being connected to a source of pulsating current, now begin to pulse ata rate of twenty-pulses per second. Ground on conductor B02; completes a circuit through resistance 4M and; the upper winding of polarized relay M10 to battery to hold the back contact of that relay closed. For a similar purpose a circuit is closed by ground on conductor 802 through the upper winding of relay 20I and resistance 202 to; battery and through resistance Bill to theupper windingof relay 9% and battery. In addition, ground on conductor 8B2 completes a circuit for relay 402; Relay 2&3 operates in a circuit from battery through its winding over the-back contact of magnet 55? or over the b ack contact of relay 294 to conductor 862, while relay $02. operates in a circuit from battery t h its winding, conductor 963, lower normal contact of key 894, back contacts of magnets 521- and 511 to grounded conductor 882.

With relay 2M energized asrabove described, a circuit is'closed' fromground on conductor 803, left, normal contact of relay 26!, upper back contact of relay 2115, conductor 20%, uppermost back contact of relay 964, conductor EH5; winding of relay 'mfizand battery. Relay 'Hiflcloses a circuit fromground onconductcr 6%!3, outer upper front contact of relay I00, conductor 'IOI, winding of magnet 5 31, which controls switch 540, and battery and in" parallel with magnet 54'! over, the outerlower contact of relay 2%, normal contact and Winding of relay 2%, resistance 291 and battery. Magnet 54! and relay 204 operate. Relay 2M locks over its alternate contact, conductor 2E8, inner upper back contact of relay 9M to grounded conductor 892. At thesame time relay 204'closes a circuit from battery through resistance 269-, winding of relay 205; alternate contact of relay ZM-toground as above traced. Relay 2G5 cannot operate, being shunted over its lower back contact by the operating circuit of relay 2%. When magnet 54'! and relay 2% have both operated, the circuit for relay 2% is opened and that relay releases, permitting relay 235 to operate. The operation of relay Ell-5 opens the circuit of relay Hill, causing that relay to release and release magnet 54! to advance switch 548 to its first operative position.

When magnet 55? releases, relay 2% reoperates. Relay 263 now closes a circuit from ground through resistance ZIG, lower winding of relay 26 I, outer upper contact of relay 263, outer upper back contact of relay 2M, middle upper front contact of relay 2S5, brush 5 53, conductor 580, upper winding of line relay m3 and battery.

Relay Hi3 is individual to the line terminals Hill and till and is the first of fifty such relays whose corresponding line terminals have been connected to line terminals on the originating frames of the office.

If relay IE3 is normal relay ZGI receives surficient current in the circuit traced to overcome the effect of the circuit through its upper winding and therefore closes its right, operated, contact to operate relay 2I2. Relay 2I2locks over its inner lower contact, inner upper back contact of relay 2II to ground on conductor 802. Relay IE3 did not receive sufficient current to operate in series with resistance 2H! but relay 2:2, in operating, connects direct ground to the winding of relay Zill in shunt of resistance lll, whereupon relay I33 operates. Relay I03 connects resistance I64 across the terminals I06 and IGI thereby simulating the action of a subscriber in originating a call. It also lights lamp N25 to indicate that the line terminals are in use. Relay I03 locks over its inner upper front contact to a contact of relay M32 which supplies the locking ground for all of the line relays.

The locking ground of relay I93 shunts the Winding of relay 2ilI and causes that relay to reclose its left contact under the influence of its'upper winding. With relay 2B5 operated, the release of relay 2M closes a circuit from ground on conductor 8%, left contact of relay 20!, inner upper front contact of relay 2G5, inner upper front contact of relay 2I2, lower winding of relay 2II and battery. The operation of relay 2II indicates that a line relay has been found normal, has been operated and has been locked. Relay 2 looks through its upper winding and inner upper contact to ground at the outer lower contact of relay 285 and in parallel therewith to ground at the outer upper contact of relay 2I2. At its inner upper back contact relay 2 opens the previously traced locking circuit for relay 2I2 but at its inner lower contact it closes a second circuit from the looking contact of relay 2I2 to conductor 208 which extends over the inner upper back contact of relay 904 to grounded conductor 852. Relay 2I2 is slow to release and therefore remains operated during, the transfer of its locking circuit.

Since key 895 has not yet been operated, relay 2H in operating closes a circuit from ground on conductor 832, outer upper front contact of relay 2H, conductor 3%, normal contact of key 895, conductor 965 to the winding of relay 994 and battery. Relay @6 5 looks over its inner upper front contact and conductor to ground at the inner lower front contact of relay 2I I. The operation of relay 984 indicates the completion of a cycle, which at this time only included the simulated initiation of a call. Relay 904 lights lamp 901 as a visual indication of the end of the cycle and also operates peg count meter 908. Relay 904 opens the operating circuit of relay 100 and the locking circuits of relays 204 and 2 I2 causing these relays to release, followed by relays 205, 2| I and 904. The slow release character of relay 2I2 delays the release of relays 2H and 904 for a definite interval,

When relay 904 has released, relay 100 reoperates and the switch 540 is advanced to operate another line relay in the manner above described. Since the line relays lock to relay 402 which in turn operates directly from start key 800, the line relays remain locked and the line closures are maintained independent of the position of switch 540,

In the manner above described one line relay after another is operated, each placing a bridge across the corresponding tip and ring terminals causing the automatic equipment to connect an idle sender and district junctor with the line terminals. When any desired time has elapsed, preferably one sufiicient to insure the connection of a sender with each line, key 801 is operated and, since it is a non-locking key, is held operated until the lighting of lamp 901 indicates the end of a cycle. Key 801 grounds conductor 208 holding

relays

204, 205 and 2I2 operated. These relays in turn hold relays 2H and 904. Key 805 is now operated to start the functioning of the code dialing circuit. Key 801 is then released and after relay 904 releases, relay 100 reoperates.

Office code dialing circuit The oilice code dialing circuit includes

switches

500, 550 and 350. With key 805 operated ground is connected over conductor 909 to the first, second and third upper armatures of relay 100. Therefore, when relay 100 operates a circuit is closed over the inner upper front contact of relay 100 to the winding of magnet 501 and battery and over the second upper front contact to the winding of magnet 551 and battery and, in parallel therewith, through the upper winding of relay 403 and battery. Relay 403 looks over its inner lowercontact, lower back contact of relay 404, conductor 405, third upper back contact of relay 904, conductor 909 to ground at the contact of key 805.

With key 005 operated the circuit of relay 203 extends, in addition to the paths previously traced, over the inner lower alternate contact of key 005 and over the back contacts of magnets 501 and 551 to grounded conductor 802 so that these magnets must also operate before relay 203 can release to bring about the release of relay 100 and the advance of switch 540. The release of relay 100 releases magnets 501 and 551 to step switches 500 and 550 to their first operative terminals.

Relay 100 in releasing also closes a circuit from ground on conductor 909, outer upper back contact of relay 100, outer lower contact of relay 403, right, normal, contact of relay 400, back contact of relay 406 to the winding of relay 401 and battery. Relay 401 locks in a circuit over its inner upper contact in parallel with relay 403 under the control of relay 904.

Relay 401 tests whether the first line relay has remained operated and locked by closing a circuit from battery through resistance 408, lower winding of relay 400, outer upper contact of relay 401, upper back contact of relay 404, brush 505 in its first operative position, conductor 58I, lower winding and inner upper contact of line relay I03, to ground at the contact of relay 402. With locking ground present, relay 400 operates, closing a circuit from battery through the winding of relay 409, outer lower front contact of relay 401, left, operated, contact of relay 400, outer lower contact of relay 403, outer upper back contact of relay to ground on conductor 909. Relay 406 locks over its inner upper front contact and the inner lower contact of relay 401 in parallel with

relays

403 and 401.

Relay 40B connects direct battery in shunt of resistance 408 to the circuit of relay 400 and the lower winding of line relay I03. The lower winding of relay I03 is opposed to the upper winding at this time and the adjustment is such that with the increased current in the lower winding, the resultant magnetic flux is insufiicient to hold relay I03 operated and it therefore releases. With the removal of the locking ground for relay I03, relay 400 also releases. However, the dial equipment is not released, since ground is connected to the ring terminal IOI over a circuit which may be traced from that terminal, through resistance I04, conductor I06, brush 503, lower contact of relay 402, conductor 409 to ground at the outer upper back contact of relay 30I When relay 400 releases, it extends the ground which was connected as above traced to its armature, over its right contact, outer upper front contact of relay 40B, inner upper contact of relay 403, conductor 4I0, back contacts of

relays

302 and 303 to the armature of relay 300 which is pulsing at a rate of twenty pulses per second as previously described.

With the armature of relay 300 grounded the first subsequent closure of its left contact completes a circuit over the inner upper back contact of relay 30!, winding of relay 304 and .battery. Relay 304 operates and looks over its lower contact and the back contacts of

relays

303 and 302 to ground on conductor 4I 0. When relay 300 then closes its right contact, it extends ground over the upper contact of relay 304, lower back contact and winding of relay 30I to battery. Relay 30! also operates, locking in parallel With'relay 304. With relay 30I operated the left contact of relay 300 is connected over the inner upper front contact of relay 30I to the winding of magnet 353, while the right contact of relay 300 is connected over the outer upper front contact of relay 30I to conductor 409 and the ring terminal IOI. When relay 30! operated it disconnected steady ground from that terminal but since the right contact of relay 300 is closed at the time that relay 30I operates, the ring terminal is grounded over the contact of relay 300.

As relay 300 pulses, therefore, it alternately operates stepping magnet 353 and opens the ring conductor toward the dial equipment to transmit an impulse thereto. Relays 3M and 304 serve to prevent the transmission of mutilated first pulses to the magnet 353 and the dial equipment. In order to determine the value of the digit to be transmitted, the terminals of brush 35! are crossconnected to the terminals of brushes 553 and 554 in accordance with the selected designations. It may be noted that brushes 053 and 554. While connected in parallel are arranged at degrees to one another so that only one brush is effective at a time. When brush 320i reaches the terminal cross-connected to the first terminal of brush 553, a circuit is closed from battery through the winding of relay 302, brushes 35I and 553,

lower back contact .of relay Z43, conductor 2H,

outer upper contact of relay 4-03, conductor 4! l, inner upper contact of relay 203 to ground at the outer upper front contact of relay 205. Relay 302 operates and looks over its inner lower front contact and off-normal contact 355 of switch 350.

With relay 3E2 operated, ground is connected to conductor 409 to hold the dial equipment. Relay 302 disconnects ground from the armature of relay 300 to stop the pulsing. It also closes an obvious circuit for relay 303 which in turn closes a circuit from ground at its upper contact, over oif-norrnal contact 356 to the winding of release magnet 354 and battery, restoring the switch 350 to normal. With switch 350 normal,

contacts

353 and 355 are opened and relay 332 releases, followed after an internal, due to the slow release character of relay 303, by the latter relay. Relay 303 is made slow enough to allow time be tween digits for the subscriber sender circuit relays to properly function and be ready for the next digit.

When relay 303 operated it also connected ground to conductor 403. In addition, relays 302 and 303 open the locking circuit of relays 30! and 304 thereby causing these relays to release and connect ground to conductor 903.

Relay 3.32 in operating closed a circuit from ground at its inner upper contact, normal contact and winding of relay 2M to battery. Relay 2M looks over its alternate contact, conductor 2H3, third upper back contact of relay 8104 to ground .over conductor 000. At the same contact relay 2M closes a circuit for relay 293 but relay 2l3 cannot operate, being shunted at its upper back contact by the operating circuit for relay 2 l 4. When relay 302 releases as above described, relay 2E3 operates, opening the circuit over brushes 553 and 554 and connecting ground to brushes 55! and 552.

When relay 333 recloses its back contact, the armature of relay 300 is again grounded and relays 3M and 33 i operate followed by the transmission of the second code digit. Relay 302 operates at this time over brushes 35! and 53! to ground at the front contact of relay 2l3. Relay 303 is operated, relays 3t! and 360 released and switch 330 restored to normal as previously described. With relay 2 l 3 operated, relay 332 closes a circuit from ground over the inner upper contact of relay 302, upper front contact of relay 2i3, conductor 2E0, lower winding of relay 434 and battery. Relay 004 closes a locking circuit for itself from battery through its upper winding and inner upper front contact, inner upper back contact of relay I to ground over conductor 009.

With relay 404 operated, a circuit is closed from ground over the outer upper front contact of relay 400, brush 505, conductor 53!, two windings of relay I03 in series to battery. In this circuit the current flow in the lower winding of relay ltii aids that in the upper winding and relay I03 reoperates, locking as before. The operation of relay 403 also opens the locking circuit of

relays

403, 003 and 407 and these relays release.

In the meantime the next line relay has been operated and locked over switch 5 and relay 2 operated as previously described. However, with key 0&5 operated the circuit by which relay 2H operated relay 334 is open. When relay 404 has also operated, a circuit is closed from battery through the winding of relay 904, conductor 905, lower normal contacts of

keys

808 and 800, lower front contact of relay 404, upper alternate contact of key 805, conductor 80,0, outer upper front contact of relay 2i l to ground over conductor 802. Therefore, both cycles must have been completed before relay 904 canoperate. Relay 964 performs the previously described functions .with regard to the dial tone seizure circuit. For the code dialing circuit it releases relays 2 l 3, 2 l4 and 434. When relay 2E2 has released, relay 004 releases and after the previously described operations relay I00 operates to start a new cycle.

Thousands and hundreds digit die-Zing circuit Again any desirable number of cycles is permitted to take place as indicated by the lighting of lamp 301. Key is again operated to prevent the release of relay H2 and when lamp 00'! lights, key 809 is operated to start the dialing of the thousands and hundreds digits. Key 801 is then released, permitting relay 2l2 and the other relays to release.

With key 000 operated the circuit of relay 263 extends, in parallel with the branches above traced, over the inner lower alternate contact of key 805, outer upper contact of key 809 and the back contacts of magnets 5i! and 551 to grounded conductor 802. Therefore, relay 203 can release only if magnets 5537, 5H, 5H, 55'! and 551 have operated as well as relay 2%. At its middle lower alternate contact, key 80?! connects grounded conductor 832 to conductor 609, which extends through resistance T04 and the lower winding of relay 05 to battery to hold the left, normal, contact of relay I05 closed.

When relay 103 operates, the circuits previously traced are closed, and in addition circuits are closed from battery through the winding of magnet 5!! to the inner lower front contact of relay I00 and from battery through the winding of magnet 53'! to the second lower front contact of relay I00 and thence in parallel to ground at the inner upper alternate contact of key 803. Magnets 5H and 55? operate in synchronism with the other magnets. Relay 300 also closes a circuit from ground on the inner upper contact or" key 809 over the third lower front contact of relay 1'00, lower winding of relay 102 to battery. Relay 102 operates and locks in a circuit from battery through its upper winding and upper contact, conductor E03, upper back contact of relay 005, to ground on conductor 609.

When, subsequently, relay 130 releases, magnets 5l'l and 50'! in turn release, advancing switches 5| 0 and 563 into association with the line terminals I00 and I05. At this time a circuit is closed from battery through the winding of relay 105, back contact of relay M67, and left contact of relay 1'05, lower contact of relay Hi2, inner lower back contact of relay M0, to ground at the inner upper contact of key 8&3. Relay 7&5 locks to ground over conductor 7233 as above traced. With relay 106 operated, a circuit is closed from battery through resistance H33, up per winding of relay Hi5, outer lower front contact of relay 75-6, brush 555 to conductor 5? and the lower winding of relay I03. As in the previously described circuit, if relay N33 is locked, relay operates and closes a circuit from battery through the winding of relay T31, inner lower front contact of relay 106, right, operated, contact of relay E05, lower front contact of relay H 2, inner lower back contact of relay "930 to ground at the contact of key 809. Relay 70'! looks over conductor 103 and connects direct battery in shunt of resistance 108, releasing relay Hi3, which in releasing also releases relay N35. The ring terminal IOI of the first line is now connected over conductor I 08, and brush 5I3, lowermost front contact of relay 402, lowermost contact of key 809 to groundat the outer lower back contact of relay I! so that the dial equipment does not release.

With relay I released, ground is extended from the contact of key 009 over the inner lower back contact of relay I00, lower contact of relay I02, left contact of relay I05, outer upper front contact of relay I01, conductor I09, back contacts of relays I08 and I09, to conductor H0 and the armature of relay I02 which is pulsing at twenty pulses per second as mentioned above.

The thousands and hundreds digit dialing circuit functions in the same manner as the code dialing circuit, the first cycle of relay I02 operating relays III and I01. Relays III and I0? lock to conductor II 0, relay I 01 connecting the left contact of relay I02 to the Winding of the step- .ping magnet I53 of switch I50 and connecting the right contact of relay I02 to the ring line terminal, at the same time removing the holding ground. The terminals of brush I5I are cross-connected to terminals of

brushes

503, 564, 565 and 506 in accordance with the selected designations. Therefore, when brush I5I reaches the terminal cross-connected to the first terminal of brush 503 a circuit is closed from battery through the Winding of relay I08, brushes I5I and 503, outer upper back contact of relay 60I, conductor BIO, inner lower front contact of relay 205, inner lower contact of relay 203 to ground.

Relay I08 operates and locks to off-normal contact I55, in turn operating relay I09. tion, relay I08 grounds the ring conductor, and disconnects ground from conductor IIO to arrest pulsing. Relay I09 operates release magnet I54, restoring switch I50 to normal. Relay I08 closes a circuit from ground at its inner lower contact, conductor II2, normal contact and winding of relay 002 to battery. Relay 602 looks over conductor 6, second lower back contact of relay 904 to grounded conductor 802. It also prepares the circuit of relay Bill which is shunted by the operating circuit for relay 802.

When switch I50 reaches normal, relay I 08 releases, permitting relay 00I to operate. With relay 00! operated, the circuit of relay I08 over brushes 503 and 504 is opened and a new circuit is prepared over brushes 505 and 569, outer upper back contact of relay E03 and the outer upper front contact of relay- Bill, to ground over conductor I I2 as previously traced.

When relay I08 releases, it opens the circuit of relay I09, which releases slowly to permit the sender functions to be completed. When relay I09 closes its back contact, relay I02 becomes operative again and the hundreds digit is sent out in the same manner as the thousands digit. When relay I08 operates following the hundreds digit, it closes a circuit from ground at its inner lower contact, conductor II2, inner upper front contact of relay Bill, to the windings of relays 603 and 004. Relay 003 operates slightly later than relay 004 due to a shunt over the normal contact of relay 604 which opens as soon as the latter relay operates. Relay 604 closes a locking circuit for itself and relay 603 to conductor BI I.

Relay 004 at its upper armature disconnects ground on conductor 609 from conductor I03, releasing relays I02, I00 and I01. When relay I00 releases ground is closed from conductor 009, over the upper front contact of relay 604, con- In addiductor 6I2, back contact of relay I06, brush 5I5 is relay I00 to, in eifect,

to conductor 58I and the windings of relay I03 in series. As before, relay I03 operates and locks to hold the dial equipment.

With relay 603 operated a circuit is closed from ground on conductor 6I0 over the outer upper front contacts of relays GUI and 603 to the winding of relay 9I0 and battery. Relay 9I0 locks to ground at the lower contacts of relays GUI and 603.

The operation of relay 9I0 indicates the completion of the function of the third circuit unit. In the meantime relay 2 has operated to indicate the completion of the cycle by the first circuit and relay 494 may or may not have been operated by the termination of the sending of the code digits. If relay 404 operates early it cannot cause the operation of relay 904, since the circuit by which the joint operation of relays 2H and 404 operated relay 904 is now open at key 809.

It will be remembered that at the time the start key was operated, relay 902 was operated. With relay 902 operated, the joint operation of relays 2I I, 404 and 9I0 completes a circuit for relay 904 which may be traced from battery through the winding of relay 904, conductor 905, lower normal contact of key 808, inner upper contact of relay 9I0, upper contact of relay 902, conductor SI I, inner lower alternate contact of key 809, lower front contact of relay 404, upper alternate contact of key 805, conductor 808, upper front contact of relay 2 to grounded conductor 802.

Relay 904 operates and advances the three circuits to the next cycle as previously described. In 6cnperating, relay 904 also releases relays GM to 4.

Again the circuits are permitted to advance through a few cycles, after which hold key 801 is operated to arrest the operation and, when lamp 90! lights to indicate the end of a cycle, key 804 is operated and key released.

Tens and units digit dialing circuit With key 804 operated the circuit of relay 902 is opened and that relay releases. Key 804 also extends the circuit of relay 203 over inner lower alternate contact of key 804, and the back contacts of magnets 521 and 51! to grounded conductor 802 so that these magnets must also operate prior to the release of relay 203. At its upper alternate contact, key 804 connects grounded conductor 802 to conductor 3I0, resistance 220, the upper winding of relay 22I and battery,holding the armature of that relay against its normal, right, contact. In addition it connects battery through relay 305, over conductor 309 and the outer lower alternate contact of key 804 to conductor 9I5 in parallel with provide additional contacts for relay 100.

When relay 305 operates, in parallel with relay I00, it connects conductor 802, over its lower contacts to

conductors

301 and 308, operating magnets 52! and 571. In addition, it closes a circuit from battery through the lower winding of relay 309, upper front contact of relay 305, conductor 3I0, upper contact of key 804 to grounded conductor 802. Relay 309 operates and locks in a circuit from battery through its upper winding and upper front contact, conductor 3I I, upper back contact of relay 608 to ground over conductor 3I0.

When relay 305 releases, switches 520 and 510 step to their first operative positons. Relay 305 also extends ground from conductor '3l'9, over the back contact of relay 305, lower contact of relay 309, conductor 3H2, right contact of relay 22!, back contact of relay 22-2, winding of relay 223 and battery. Relay-223 locks to conductor 3!! and connects ground over its outer lower contact, outer upper back contact of relay 224, brush 523, to the ring conductor I56 to hold the dial equipment. Relay 223 also connects battery through resistance 22'! and the'lower winding of relay 22!, outer upper front contact of relay 223, brush 525 to conductor58l, and the two windings of relay I53. With relay I93 locked, relay 22! operates, in turn operating relay 222 which locks to conductor 3H. Relay 222 connects direct battery to the winding of relay 22!, releasing relay I93 in the mannerpreviously described, followed by the release of relay 22!.

Ground on conductor M2 is now extended over the right contact of relay 22 I, lower front contact of relay 222, back contacts of relays 226 and 225 to conductor 229 and'the armature of relay 290.

Relay 299, which is pulsing at twenty pulses per second, operates relays 2'28 and 224 to absorb the first cycle, these relays looking to conductor 229. With relay 225 operated the right contact of relay 299 is connected'to the winding of the stepping magnet 253 of switch 259 while the left contact of 'relay 290 is connected to brush 523 and the ring line conductor. The tens digit is transmitted to the dial equipment and switch 255 advanced.

The terminals of switch 259 are cross-connected to the terminals of brushes 51! and 514 in accordance with the selected designations and, when brush reaches the terminal cross-connected to the first terminal of brush 513, a circuit is closed from battery through the winding of relay 226, brushes25! and 513, outer'upper back contact of re1ay'655, conductorGHl-to ground as previously traced. Relay 225 locks'to off-normal contact 255, disconnects ground from conductor 229 to stop the pulsing and release relays 2124 and 228, connects ground to the ring conductor to holdthe dial equipment, and operates relay 225. Relay 225 operates release magnet 254 to restore the switch 259 to normal and adds ground to the ring conductor.

Relay 225 connects ground over its outer lower contact to conductor 23%, normal contact and winding of relay'fiflfi to battery. Relay 596 locks to conductor 6! preparing a circuit for relay 695. When switch 25!] returns to normal relay 225 releases and relay 695' operates. Relay 226 opens the circuit of relay 225 but that relay releases slowly to permit the sender to prepare for the neXt digit.

With relay 225 released, conductor 229 is grounded again and the units digit is sent out; At this time the circuit of relay 226 extends over brushes 25! and 57!, outer upper back contact of relay 691, outer upper front contact of relay 695 to ground over conductor 6|9. When relay 225 is operated by the arrival of brush 25! at the cross-connected terminal, the same operations take place as at the end ofthe tens digit. However, the connection of ground to conductor 23!] now completes a circuit over the inner upper front contact of relay 655 to the windings of relays 59'! and 698 which operate in the manner of relays G93 and 694.

The operation of relay 6% opens the locking circuit of relay 226, permitting thatrelay to release, and'closes a circuit from ground on conductor 3E9, upper'front contact of relay 658, conductor 5!'!, back contact of relay 223, brush 525 to conductor 58! and the windings of relay I93. Relay Hi3 operates and locks as previously described.

With relays 555 and 59? operated, ground on conductor 5 I 9 extends, over the outer upper front contacts of relays 555 and 55?, to conductor 983 and the winding of relay 992. The operation of relay 992 is now an indication that the tens and units digit dialing circuit has completed its operation. The circuit for operating relay 994 is, therefore, the same asrbefore this latter dialing circuit was started. Relay 9 i '9 looks under the control of relays 55!, 953, 595 and 551 while relay 992 looks under the control of relay Sit. Relay 994 opens the locking circuits of relays 555 to 698 used in this circuit as well as those of the relays looked under its control in its other circuits.

When an additional number of cycles have taken place, key 89! is again operated to stop the circuit, key 855 is operated and key 89'! released.

Line disconnect circuit The operation of key 593 connects the back contact of magnet 53'! in parallel with the other magnet contacts in the circuit of relay 203. It also connects ground over its inner upper contact to the outer lower armature of relay 199 to provide an operating circuit for magnet 531, and relay 9i2 which is closed when relay 15!] operates.

Relay 9S2 locks in a circuit from battery through its lower winding and lower contact, conductor 9H, inner lower-back contact of relay 904 to grounded conductor 892. When relay 109 releases, ground from the contact of key 8513 extends over the outer lower back contact of relay 789, conductor H9, upper contact of relay 9I2, right, normal, contact of relay 995, back contact of relay 9M, winding of relay 9H5 and battery. Relay 9l5 locks to conductor 9!'!.

With relay 9H5 operated a circuit is closed from battery through resistance 9 63, lower winding of relay 995, upper contact of relay 9!6, conductor 9l9, brush 533, conductor 58!, lower winding of relay N33 to ground over the upper locking contact of relay I53. Relay 99B operates in this circuit, closing a circuit from ground on conductor H0, upper contact of relay 9l2, left, operated, contact of relay 9%, outer lower contact of relay 9H5 to the winding of relay 9M and battery. Relay 5M operates and locks to conductor 9!'!.

Relay 9M connects direct battery in shunt of resistance 9H3, causing relay I93 to release, in turn releasing relay 9%. No circuit is provided to hold the dial equipment at this time, therefore the switches connected with line terminals I90 and ID! are permitted to restore.

When relay 999 releases, a circuit is closed from ground on conductor H9, upper contact of relay 9!2, right contact of relay 950, upper front contact of relay 9M. to the winding of relay 920 and battery. Relay S29. operates and locks in a circult from battery through its lower winding and contact to ground over conductor 258'.

With key 858operated the circuit for relay 994 used following the start of the tens and units dialing circuit is opened and a circuit closed which depends on the completion of its cycle by each of the five circuit units. This circuit may be traced from battery through the winding of relay 994, conductor 955, upper contact of relay 929, lower alternate contactof key898, innerLupper contact of relay 9H], upper contact of relay 992, conductor 9! inner lower alternate contact of key 809,

lower front contact of relay 404, upper alternate contact of key 895, conductor 806, inner upper front contact of relay 2!! to grounded conductor 802.

The circuit now proceeds to originate calls on the line terminals, one after another. Lamp 90'! provides a visual indication of the speed with which the complete calls are put through while the line lamp, such as lamps I05 and !25, provide an indication of the spacing between the operations of the various units.

When it is desired ot stop the circuit, key 800 is released releasing all relays which may be locked at the time. Switches which are oif-normal may be restored by means of the stepping keys individual thereto which receive ground from key 800 in its normal position.

Terminals 2!5, 2I6 and (M3 to M6 are used to control the dialing of irregular designations such as permanent signal, zero operator or partial di-' aling. To omit the corresponding digit, terminal 2 I6 is cross-connected to the desired terminal of brush 553 or 554, terminal 2!5 to the terminal of brush 55! or 552, terminal 5!3 to that of brush 563 or 554 and so on.

For example, if a permanent signal condition is to be sent, in a particular position of switches 55!), 56c and 5%, all of the cross-connecting terminals 255, M5 and M3 to GIG will be connected to the brush terminals in this position. Therefore, as soon as relay 235 has operated and relay 293 reoperated, grounding conductor 2H, as above described, a circuit will extend from conductor 25'! over the lower back contact of relay 2l3, brush 553, terminal 2H5 to the windings of relays 2 l3 and 2 M which operate immediately.

With relays 2i 3 and 2M operated a circuit is closed from ground at the lower front contact of relay 2 !3, brush 55!, terminal 2 !5, upper contact of relay 2M to conductor 2 9 to operate relay 404. Similarly, when switch 550 reaches the corresponding position, the operation of relays 253 and 2555 closes a circuit over conductor 5H), back contact of relay 86!, brush 563, terminal 6! 3 to the windings of relays 6%)! and SE32 which operate at once. Relay 66! extends the circuit to brush 565 and terminal 6M thereby operating relays 853 and tea to in turn operate Sill. In a similar manner relays 505 to 608 are operated to in turn operate relay 982. The release and reoperation of the line relay takes place whether or not the digits are transmitted. While in the circuit shown provision has been made for two digit office codes the adaptation for use in a three digit o-ffice-would be made readily.

It may be noted that since switche 560, am, 523, 53:; and 54s have twenty-five sets of terminals and switches 55%, 56!! and 570 have twenty two sets of terminals, different designations will be transmitted each time a line is seized until each designation has been sent out over each line.

What is claimed is:

1. In a telephone system, automatic switching equipment, lines having access to said switching equipment, and means to operate said equipment in simulation of service conditions comprising means for automatically connecting with and closing a particular plurality of said lines one at a time, other means for connecting with said lines and transmitting predetermined telephone designations over said lines in turn and additional means for connecting with each of said lines and opening said lines in turn.

2. In a telephone system, automatic switching equipment, lines having access to said switching 7 equipment, and means to operate said equipment in simulation of service conditions comprising means for automatically connecting with and closing a particular plurality of said lines one at a time, means efiective after a predetermined number of said lines have been closedfor connecting with said lines and transmitting predetermined telephone designations over said lines in turn and means effective after a further predetermined number of lines have been closed for connecting with each of said lines and opening said lines in turn.

3. In a telephone system, automatic switching equipment, lines having access to said switching equipment, and means to operate said equipment in simulation of service conditions comprising means for automatically connecting with and closing a particular plurality of said lines one at a time, means effective after a predetermined number of said lines have been closed for connecting with said lines and transmitting predetermined telephone designations over said lines in turn, means efi'ective after a further predetermined number of lines have been closed for connectlng with each of said lines and opening said lines in turn, and manual means for predetermining said number of lines and said further number of lines.

4. In telephone system, automatic switching equipment, lines having access to said switching equipment, and means to operate said equipment in simulation of service conditions comprising means for successively originating a call, dialing an ofiice code, dialing a numerical code and terminating a call over each of said lines at predetermined overlapping intervals and means for maintaining said intervals throughout the operation of said equipment.

5. In a telephone system, automatic switching equipment, lines having access to said switching equipment, and means to operate said equipment in simulation of service conditions comprising call originating means, means for connecting each of said lines in turn with said call originating means to originate a call thereover, a plurality of dialing means, means for connecting each of said dialing means with each of said lines in turn to transmit a telephone designation thereover, call terminating means, means for connecting said call terminating means with each of said lines in turn, manual means for controlling the relative time of connection of said call originating means, said dialing means and said call terminating means with the first of said lines and means for automatically advancing said connecting means and maintaining said relative time of connection with the remainder of said lines.

6. In a telephone system, automatic switching equipment, lines having access to said switching equipment, and means to operate said equipment in simulation of service conditions comprising call control means including as elements call originating means, a plurality of dialing means and call terminating means, connecting means for connecting each element of said call control means to said lines'in turn and means to control said connecting means to simultaneously connect each element of said call control means with difierent lines.

7. In a telephone system, automatic switching equipment, lines having access to said switching equipment, and means to operate said equipment in simulation of service conditions comprising means for successively originating a call,

dialing an ofiice code, dialing a numerical code and terminating a call over each of said lines at predetermined overlapping intervals, means for maintaining said intervals throughout the operation of said equipment, and means for controlling said dialing means to dial a difierent office code: and numerical code in connection with calls originated over successive lines and with successive calls on any one of said lines,

8. In a telephone system, automatic switching equipment, lines having access to said switching equipment, means to operate said equipment in simulation of service conditions comprising means for automatically and repeatedly closing aparticular plurality of said lines one at a time, means for transmitting telephone designations over said lines in turn, means for automatically opening said lines in turn, and means for controlling said designation transmitting means to transmit a different telephone designation over each of said lines following each closure of said lines.

9. In a telephone system, automatic switching equipment, lines having access to said switching equipment, means to operate said equipment in simulation of service conditions comprising a plurality of sets of line terminals connected to a plurality of said lines, a relay individual to each said set of line terminals, a plurality of multiposition switches, means to operate said switches to successively connect with each set of line terminals and the relay individual thereto in turn, means to operate each of said relays to close a bridge across the corresponding set of line terminals, means controlled over each of said switches in each position to release the connected said relay and substitute a dialing connection for said bridge, means to transmit a plurality of digits over said dialing connection, and means to reoperate said relay to restore said bridge.

10. In a telephone system, automatic switching equipment, lines having access to said switching equipment, means to operate said equipment in simulation of service conditions comprising a plurality of sets of line terminals connected to a plurality of said lines, a relay individual to each said set of line terminals, a pluralityof multiposition switches, means to operate said switches to successively connect with each set of line terminals and the relay individual thereto in turn, means to operate each of said relays to close a bridge across the corresponding set of line terminals, means controlled over each of said switches in each position to release the connected said relay and substitute a dialing connection for said bridge, means to transmit a plurality of digits over said dialing connection, means to reoperate said relay to restore said bridge, an additional switch having access to said line terminals and means operated over said additional switch to release each of said relays in turn.

11. In a telephone system, automatic switching equipment, lines having access to said switching equipment, means to operate said equipment in simulation of service conditions comprising a plurality of sets of line terminals connected to a plurality of said lines, a plurality of multi-position rotary switches having access to said line terminals, means controlled over each switch for establishing a dialing connection with eachset of line terminals in turn, a plurality of other rotary switches having a different number of positions, means effective in each position of said other switches for controlling said dialing con nections in accordance with different telephone designations, and means'for advancing one of said multiposition switches and one of said other switches simultaneously through a plurality of rotations to dial a plurality of different designations over each set of line terminals.

12. In a telephone system, automatic switching equipment, lines having access to said switching equipment, and means to operate said equipment in simulation of service conditions comprising call control means including as elements call originating means, a plurality of dialing means and call terminating means, connecting means for connecting each element of said call control means to said lines in turn, means in each of said elements responsive to the operation of said element for preparing the associated connecting means for advance, and means under the joint control of the responsive means in all of said elements to simultaneously advance all of said connecting means.

13. In a telephone system, automatic switching equipment, lines having access to said switching equipment, and means to operate said equipment in simulation of service conditions comprising call control means including as elements call originating means, a plurality of dialing means and call terminating means, connecting means for connecting each element of said call control means to said lines in turn, manual means for successively starting each of said elements, means in each of said elements responsive to the operation of said element for preparing the associated connecting means for advance, means to advance said connecting means, and means under the control of said manual means for successively placing said advancing means under the joint control of the responsive means of the elements which have been started.

14. In a telephone system, automatic switching equipment, lines having access to said switching equipment and means to operate said equipment in simulation of service conditions comprising call originating means, first connecting means for connecting said call originating means with each of said lines in turn to establish a bridge across each line to originate a call thereover, the first means operated responsive to the establishment of said bridge to control the advance of said first connecting means to the next line, a plurality of dialing means, other connecting means for connecting each of said dialing means to each of said lines to transmit a telephone designation thereover, other means operated responsive to the completion of each of said dialing operations to control the advance of said other connecting means to the next line, call terminating means, aditional connecting means for connecting said call terminating means with each of said lines in turn to disconnect said bridge, further means responsive to the disconnection of said bridge to control the advance of said additional means to the next line, manual means for controlling the relative time of connection of said first connecting means, said other connecting means and said additional connecting means with the first line of said plurality of lines, and means for automatically maintaining said relative time of connection for each of said lines.

15. In a telephone system, automatic switching equipment, lines having access to said switching equipment and means to operate said equipment in simulation of service conditions comprising call originating means, first connecting means for connecting said call originating means with each of said lines in turn to establish a bridge across each line to originate a call thereover, the first means operated responsive to the establish ment of said bridge to control the advance of said first connecting means to the next line, a plurality of dialing means, other connecting means for connecting each of said dialing means to each of said lines to transmit a telephone designation thereover, other means operated responsive to the completion of each of said dialing operations to control the advance of said other connecting means to the next line, call terminating means, additional connecting means for connecting said call terminating means with each of said lines in turn to disconnect said bridge, further means responsive to the disconnection of said bridge to control the advance of said additional means to the next line, manual means for controlling the relative time of connection of said first connecting means, said other connecting means and said additional connecting means with the first line of said plurality of lines, and means operated under the joint control of said first responsive means, said other responsive means and said additional responsive means to simultaneously advance all of said connecting means.

LLOYD T. MEEDS.