US1659832A

US1659832A - Testing equipment for automatic telephone systems

Info

Publication number: US1659832A
Application number: US49226A
Authority: US
Inventors: Martin L Nelson
Original assignee: Automatic Electric Inc
Current assignee: Automatic Electric Inc
Priority date: 1925-08-10
Filing date: 1925-08-10
Publication date: 1928-02-21
Anticipated expiration: 1945-02-21

Description

Feb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug. 10, 1925 PIfECTOE 4 65456701? E i P T lllllllllllllllllll M m M W S p Jr v w w 7% 9 7 ET n M M 4 K m 4 4 Wm H N, s F 7 a D Haw H mm 50 J. 2 o o o o o r@ o o o o l/o jw/o f/o/f -Inusn or l fl'ar'hn L. Nelson Feb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS eats-Sheet Inuen Elf- \Q a i x3:

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E H?!" L.Ne'lsun fi m Filed Aug. 10. 1925 4 Feb. 21,1928. 1,659,832

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug. 10 1925 10 Sheets-Sheet 3 TEST SEA/DER fol 10.9

Filed Aug. 10. 1925 M L NELSON TESTING EQUIPMENT FORAUTOMATIC TELEPHONE SYSTEMS Feb. 21, 1928.

Im.rsn CIT-- l L arZm L. NEZsun fimdfl Feb. 21, 1928.

L. NELSON TES TING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug. 10. 1925 10 Sheets-Sheet 5 N M Q QQMRZOU MMQENW hWMh Feb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug. 10. 1925 10 Sheets-Sheet 6 Inusn UI- Hm L. Nslsun Feb. 21,-1928.

" M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug. 10. 1925 10 Sheets-Sheqt -Inusn m: Mar 111 L.Na1sun N 3 MR his NQQ Feb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug. 10. 1925 10 Sheets- Sheet 8 I: Jun- M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Feb. 21, 1928.

H a M M M knwR Feb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug. 10. 1925 10 Sheets-Sheet. 1o

M b H M M a M Q I ance will be accurate and reliable.

Patented Feb. 21, 1928.

entree STATES v 1,659,832 PATENT OFFICE.

MARTIN L. nntsoinor :PARKRIDGE, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,

T0 AUTOMATIC ELECTRIC INC, OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- V WARE.

TESTING EQUIPMENT FOR AUTOIVIATIC TELEPHONE SYSTEMS.

Application filed August 10, 1925. Serial No. 49,226.

of directors and which intercepts the digits that the director sends out and records them as received properly or improperly.

In the so called director system, a relatively small number of directors'are em ployed in common to a group oftrunks to register, translate and retransmit thedigits of telephone numbers. As soon as these digits have been retransmitted, the director disassociates itself from the trunk and can not be readily further identified with the pending call, inalrin it very difficult to determine just which director is not functioning properly. Therefore it is imperative to good service that the directors be kept in first class condition so that their'perforn'i- The best known way of keeping such equipment in reliable order is by routining it, that is, by frequently applying characteristic tests, which, if properly executed indicate that the equipment is functioning properly. The director has many functions to perform, and

in order to definitely determine that the mechanism is performing all the functions properly, a large number of separate tests must be included in the routine. If these tests are applied manually, a considerable period of time is required for each director and the maintenance costs are therefore made unduly high.

Accordingly, the principal object of this invention is the provision of a director routine test mechanism which will automatically routine a group of directors without attend? ance, other than that required to start-the mechanism and to record and repair the faults found. I

A further object is to provide a testing mechanism which seizes each director in its consecutive order, applies a test to it and if the test is properly completed, releases that director to common usage and seizes the next,

' on which the same test is applied.

Another object of this invention is to provide a testing mechanism which, is arranged to camp on a busy director, if that director is engaged in setting a call, and to skip a busy director, if that director is made per-' manently busy by means of the director busy key provided for the purpose.

A still further object of this invention is to provide-attesting mechanism arranged to apply a large number of tests to each director, and still further arranged. so that it changesfrom one test to another after the Y former test has been applied to all of the directors in the group. i

A still further object of this invention is to provide a testing mechanism which, when a fault is found will indicate which director defaulted, and the exact nature of the fault,

and which will hold the director and test mechanism in place While a signal is sounded to summon the attendant to the mechanism to locate and repair the fault.

' A further object of this invention is to provide a test mechanism which will exercise a director, that is, repeat the same test on any director indefinitely, to make sure.

that that mechanism functions properly.

A still further object of this invention is to provide atest mechanism, which willroutine a single director, that is, run all of the routine tests on a director to inake sure that that mechanism is functioning properly.

Further objects of this invention whicl are not specifically enumerated here will be description and apparent from the detailed claims which follow.

The drawingsrcomp'rising Figs. 1 to 10, inclusive, when arranged as shown in Fig. 11, show suflicient details to enable a clear understanding of the construction and operation of my invention.

Figure '1 shows a director mechanism together with the trunk circuit which renders it available to the director selector and to the test mechanism.

Figure 2 shows the test director selector, which connects with the directors to be tested and controls the application of tests thereto.

Figure 3 shows the test sender mechanism by which a certain number is sent into the director to set the mechanisms therein in their proper. positions to perform the desired tests.

Figure 4 shows the test selector mechanism which determines which otthe severaltests will be applied. to the directorthat is being tested.

Figure 5 shows the test sender control relays comprising two groups; one group Which controls the digits and the other group which controls the impulses in. the digits.

Figure 6 shows the test set up relays A by means of which it is determined what number will be: sent into the director and what number must be received fro nthe;

director by tlie test mechanism, in testA,

Figure? shows the receiver control re-. layswh ch count. the impulses received iromthe, director. to determine whether or; not.

the translated number. has been properly sent, by, the dir-ec iOl. shows the, impulse lamps.numbered, conl t iv y r m .0 o 1 inclusi e, y ans. of which a .i'ault. islocated,

Figure 8-.shiow-s-the receiver digit; controlrelaysby'meanso'f which tliedigits to. be.

received are determined in cooperation with the set-up relays-of Fig. 6 and alsothe digit lampsby means of which the fault is located withv respect tothe digits. I

Figure 9 shows a. second test setup, relay group hereafter designated test C, which is arranged to replace Fig. 6 and to control the sender and receiver mechanism when test C is being made in a manner which will be explained more fully hereinaafter.

FigurelO similarly istanother test set-up controhherea'iter designated as test D, which. isarranged to replace F ig. 6 and to.,control the sender and receiver mechanisms whentest D; is-being transmitted as will be. eX-

plained hereinafter,

Inan actual installation Lpropose to. mul-..

tiple' the digitand impulse wires from the sender control relays, shown in Fig. 5, to a;

pluralityof terminal pins on thesender TDF shown in Fig. 6, andiin a, similar manner to; multiplethe. impulse and digit wires fromthe receiver control relays showniin Figs. 7 and 8 to a plurality of terminal pins on the receiver IDF shown in Fig. 6. The test setup relaysA, shown in Fig. 6 are connected to one set ot terminal blocks', both in the. sender and receiver IDFZs, illiClSlDlllLIlY the This drawing also be explained, the drawings showing that test set-up is substituted for the former drawing, it. being'understood that this arrangement does not designate an alternative test means, but is merely an arrangement to simplify the drawings as'much as possible.

It should be noted that I have shown in Fig. 6, three sets of normally closed springs, 922, 102 i, 10%, that are not associated with any relay; the two latter springs also appear in Fig. 9, and the former in Fig. 10. I hayevchosen to show certain, circuitsz'in this manner in connection with the above mentioned plan of drawing simplification.

The springs, 922 area .set of break, springson. relay 903. of test-C. Except when testQ is being employed, these spings are closed;

to connect. the director selector step conducitor 1- to the director selector, step conducton, 2. Similarly the springs 1024, which are in the relay 1009 of the test 1) connect they star-ticonductor to the start 1 conductors cept duringthe application ,o:t, tes t:D,., Also thepulse l conductor. and: the pulse 2 conductor are-joined together through. springsv 1015 except. when relay 10,07 isenergifzed during test D. These springsthatare shown detached .lirom their relays, remain closed throughout the application of the, test in which theyare so shown, and may be re.-

garded as a solid connection during' the consideration that test. v

Throughout the drawing-5. .111 order to v avoidundue complications, l have shown a plurality of batteries whereas-inreality there would be but one battery, preferably withits positive .pole grounded. v

Referring now to Fig.1 1n more detail.

I liavesl own a skeleton of a: director inechar;

nisn such asis disclosed intlull in my (10-- pendi m application Serial. No. 719,459, filed June 12, 1924. This mechanism which is common to a trunk group is accessiblethereto through the medium-oi thedirector selector, and is. operable to register, translate and retransmit the digitso't telephone num-. bers. Pi'ovidedwvitli each director is a director busy key by means of which.v that directo:v canbemade permanently busy'and,

inaccessible to the director selectors .in; the,

well known manner by'placing; ground po tential on theprivate or testing conductor.

In Fig. 2, I have shown a test director selector which is a. director selector similar to'thc regular director selector indicated in Fig. 1 by means of which the testing mechanismis connected. to the directorsto'be tested, VJith the director selector arranged. as shown n, Fig. 2, a mannnum of 24 di-.

rectors can be made available to the test mechanism,the twenty-fifth. contact of the group being utilized for other purposes, as will be apparent hereinafter. It will be ize understood that it is by of example that it I have chosen this arrangement and that by the use of a secondary switch, a maximum of 576 directors can be made available to the test mechanism.

Briefly, the operation of my invention is as follows: when the attendant starts the test mechanism by operating certainkeys, the test director selector steps its wipers on tothe trunk leading to the first director of the group. If that director is engaged at the time setting up a call, the test director selector camps there, lighting a'lamp, indicating that the director No. 1 is busy. As soon as that director becomes idle, the test director selectorseizes it and makes it busy to the regular director selector so that the test will not be interfered with. Simultaneously with the starting of the test director selector, the attendant operates the key to start the test sender impulsing relay in operation and to step the test selector into connection with the first bank contact, so that the testing mechanism is arranged to send out the first test, which is test A. The test set-up for the first test is shown in Fig. -5, the

relays

601 and 602 being energized through the banks of the test selector of Fig. l, to connect up the sender and receiver counting relays in accordance with the digits of the first test. In this test the testing mechanism is arranged to send in to the director the digits 431 in response to which the director sends out the digits 3481. In sending the digits into the director the test sender impulses in the well known manner to send ground im pulses over the impulse Wire to the director, the number of impulses being counted by the counting relays, which are arranged to cut off the impulsing when the proper number of impulses have been sent, in this case 4.. At the end of the first digit, the sender digit control relays function to connect'the impulse counting relays so that they Wlll count out the correct number of impulses for the second digit, in this case a 8, that digit being transmitted into the director in the same manner as was the first digit. In a similar manner the remaining digits are sent to the director.

I After the impulses have been transmitted into the director mechanism, it starts to send out over the loop conductors a series of digits, the nature of which is dependent upon the register mechanism setting of the director itself, as explained in detail in my.

above mentioned copending application.

Res onsive to the ulsin b the director p b d 7 the test set mechanism pulsing relay is oper ated to transmit impulses of ground to the receiving counting relays, setting up a com bination of counting relays in accordance with the number of impulses received from the director. At the end of the transmitting of the first digit the test set mechanism makes a test to determine whether or not the digit received was the digit that should be received, that test being made by projecting ground out on the fault wire which is extended through the first combination of the receiver impulse and digit counting relays back to the test conductor. If the digit was properly received, the digit control relays of 8 are operated to prepare the receiving mechanism for reception of the second digit of the call number.

When the test setup relays 601 and 602 are energized to put the sender and receiver mechanisms of the test set under the control of test set-up A, the sender mechanism is arranged to send in to the director the digits e 81, responsive to which the director must send out the digits 3431. If, for any reason, the director sends out a. wrong digit, the test loop mentioned previously will not be completed through the counting relays since those relays will be improperly set, and as a result the test director selector will lock up holding the faulty director to prevent its seizure by a subscriber, andthe test lamps will be lighted to indicate the nature of the fault. f, for example, the director sent out a first digit of 4 instead of 3, director No. 1 being tested at the time, the test lamps would be lighted to indicate that director No. 1 had defaulted and that it haddefaulted on the first digit sending out a 4; as the first digit. By reference to the test chart or any suitable record, the attendant knows that the first digit should be a 3. Inasmuch as-the test director selector is holding the faulty director in its operated position, the attendant can examine that director in detail to determine the cause of the fault. The attendant, upon finding the trouble, may repair the same, and in order to make sure that he has properly repaired the director, he will operate a so called consecutive test key on the test set mechanism.

Operation of the consecutive test key arranges the circuits of the test director selector so that the test then being applied is repeatedly applied to the same director, in this case director No. 1, to exercise that director so that the attendant may make certain that it is functioning properly.

When the attendant is certain that the director No. leis functioning properly he reoperates the consecutive test key, whereupon the test is repeated on the director No. 1 once more and if the test mechanism receives the proper combination of digits, the test director selector at the end of the test selects out and picks up director No. 2, and if that director is not busy at the time in the process of setting up a call, it immediately receives the same test on it. At the end of that test the director selector steps onin search of director No. 3, which for the moment will be assumed to be made busy by means of the director busy key. In this case the t st director selector will not camp group of on that trunk, but will advance immediately and pick up director 4, for the rerson that director N0. 3 is probably made busy because ofsome fault already known to the attendant and there would be no advantage gained in testing the director.

After the entire group of directors have been tested with the test it, explained hereinbefore, the test selector shown in Fig. 4, immediately after the completion of the test on the 24th or last director of the group. advances its wipers one step to change the test set up relay, that is, to piclt out a new test to be applied to the group directors. In Fig. 4 l have shown the test applied to the directors when the wiper 411 in the first six positions of its bank. And the Bapplied to the director when the wiper i1 is in the second 8 positions of its bani. the test C applied to the dire wiper is in the third 5 positions Oil the bani with the test 1) applied only once as be obvious from the b: 1 cans: have made thisparticuiar set-up ct selector merely by way of examp e as it is possible to apply 25 dill-oi each bank contact encount' it'd by the w 411. The test A shown on to. 6, is the most simple test to the director, exercising the mos; function of the director, in which case di ts are impulsed into a greater or lr number of digits sent out by the director mechanism. Test B, which is selected when the wiper 411 of the test selector reaches the second group of bank contacts, may be sub stantially like test A and need not be explained in detail here.

When the wiper 411 reaches the third bank-contacts, it picks out the test C, which is shown in test set-up Fig. 9. With Fig. 9 substituted for Fig. 6 between Figs. 5 and 7 and to the right of Fig. 3, the drawings are arranged to show the circuits of the test set when the test C is being made. It will be noted that the circuit is completed from the wiper 411 01" the test selector through the test control'conductor C to the windings of the relays 901 and 902., energizing those relays to place the sender and the receiver mechanisms test set under,

the control of the test C. This set is arranged to impulse into the director 111 and to receive from the director the digits 111 followed by a director cutoff. The test set up is further arranged so that the above mentioned test is repeated twice on each director before the test director selector steps on to pick out the next idle director. Because of the peculiar setting oi the director digit registers when the digits 111 are recorded, there is a possibility that these registers will not restore to normal properly when the director cuts'ofi, particularly it one of the digit registers happens to be a little register recording the third 1 of the :called number had tailedto release properly when the director was called upon to call that number ,the third digit of the number would contain t vo. impulses nstead of one. When the digits were received by the test mechanism this error in thcQt-hird digit of the number would be recorded as an indication to the attendant that the digit-register otth-c directorwas-slug ash to release. attendant would then repair the fault and exercise the director several times to make certain that he had properly adjusted the faulty mechanism, before proceeding with the test, as .set forth before. Aside vfrom this change the test set-up C is. an exact duplicate of the test A and need .not be explained further detail at this time.

When the wiper 411 of the test selector reaches the bank contact to which is attached the test control conductor D, the circuit is completed to the test set-up irel-ays 1001and 1009 of Fig. 10., to bring the sender'and receiver mechanisms of the test set underthe' control of the test D. By substituting Fig. 1.0 for Fig. (Sbetweeh Figs. 5 and 7 and to the right of Fig. 3.,the drawingsare arranged to show the circuits ot' the test .mechanism when the test set-up D is employed. The test D is arranged to test the time limit release of the director mechanism] Inasmuch as there are but a comparatively iew directors employed in an exchange it exchange would function to seize the director in the well known manner, and it no impulses were received by that director. it would not move out of normal and would become permanently out of service. Or, it a subscriber started to call a number and after dialling one or'two digits, he forgot the rest of the number or neglected to dial it, the director again would be tied up as sutli cientnumber ot-digits to release it have not yet been received. To guard against contingencies of this kind, a time limit pulse is provided which, after a definite interval, it no impulses are received by the director. causes the director to release the established train of switches and to dial agpredetermined number, which may either return a busy toneto the subscr1ber or connect the .subscrlber to a supervising operator. The test D 18 arranged to determine whether or not this.

The

Inc

rector.

The director sends out a9 and then waits. At the end of an interval the time pulse sent out by the time pulse mechanism operates both the director and the test-set mechanism,

causing the director to rel-ease and send back a and to light the lamp 413 to notify the attendant that the routine has been completed on all of the directors and that the test is ended.

. In the testing sender, shown in Fig. 3 is an interrupting relay 301 which is arranged to impulse into the director mechanism. In order that the test may be successfully carried on, it is'neces sary that this relay be maintained in standard adjustment, so that the impulses received by the director mechanism will be the same as are received by the director from the director selector when the director is beingused to set up a call. For this purpose I have provided the jack springs 320 and 321'by means of whichI can connect a testing mechanism such as shown in my copending application, Serial No. 744,- 528, filed October 18, 1924. By operating the keys 322 and 323 I am able to divert the impulses delivered by the springs 325 of the interrupting relay into the test mechanism disclosed in the above mentioned application. This mechanism is arranged to determine the speed and impulse ratio of the impulses, and serves as a guide in the adjusting and timing of the standard interrupting relay 301 of the test sender.

It may happen that the attendant, after repairing one of the director mechanisms,

may desire to place a particular one of the tests on the director he has repaired, and to repeat that test a plurality of times on that director to limber up the mechanisms he has repaired. He may do this by starting the test mechanism in the above manner, and

then by manually stepping the director selector to the desireddirector by operating the director selector step key 234, and then step the testselector to the desired test by operating the test selector stepkey. He will then operate the consecutive test key 241 to the position in which it exercises the di- In this manner the attendant is able to put a working test upon the parts of the director that he has repaired orrep'laced, and by this means he is able to definitely deter mine whether or not he has put the director mechanism in its proper working order.

In the event that the attendant desires to place all of vtheroutine tests on the director that he has repaired, he arranges the testing mechanism to exercise the director, and in additionoperates the director routine key 226. The circuits are then arranged so that at the end of a successful test, the ground pulse that normally would operate the director selector'motor magnet 212 is diverted to the test selector motor magnet 404,

energizing that magnet to advance the wipers 410-411 one step. By this arrangement all of the tests in the routine are applied to the single director.

Having thus described my invention in general, I will now proceed with a detailed description of its operation as it places the various tests upon the directors. First, I shall explain the detailed functions as the test A is appliedto the directors.

Starting me test mechanism.

In order to start the test mechanism in motion, the attendant first operates the interrupter start key 324, closing the circuit from ground through springs 324 to the winding of interrupter relay 301 and the I winding of relay 303 in seriesto grounded battery. The'relay 301 energizes over this circuit and attracts the armature 302 to close the

contacts

302 and 326, thereby shunting out the winding of relay 301 and providing a direct path from grounded spring 324 through springs 302 and 326to the winding of relay 303. Relay 303'being marginally adjusted will not energize in series with relay 301, but will'energize when the latter relay is shunted out. Relay 301 being shunted out deenergizes after a moment allowing the armature spring 302 to retract to operate the springs 325. As soon as relay 301 has removed-the short circuit from itself, relay '303 deenergizes, closing the spring 327 for a purpose which will be explained hereinafter. Relay 301 again attracts its armature 302 and, shunts itself out to energize its relay 302 and deenerg'ize itself as before. Because of the weight on the armature 302, its movement is pendulum like and timed to vibrate at'the rate of 10 per second so that the spring 325 and the relay 303 are both operated at the'rate of 10 operations per second. After havingstarted'the impulsing relay in mo tion' the attendant then operates the test step 1 key 419, closing a circuit from ground to springs 419 through the winding of relay 404 to grounded battery. The relay 404 en ergizes and prepares to advance the wipers 410 to 411 one step. This switch mechanismv being of the well known rotary line switch type, advances its wipers when the motor magnet 404 deenergizes rather than when the magnet is energized. When the attend ant releases the key419 magnet 404 deenadvancing the wipers 410 and 411 Ii I;

contact a. p 1 ground through key 420 and its break contact, springs 417, Wiper 411, noW in contact- "with bank contact .a,test control conductor tothe firstbank contact in which position the wiper'411 is in contact with the'ban'k A- 'circuit is then closed from A, through the windings or relays 002 and 601 In series to grounded battery. Relays "601 and'602 energize over this circuit, there- 'bypreparing the test sender and'test' receiver controlled to send out thetest A.

Test set-up A.

Relay 602 upon energizing'closes'a circuit "from ground through springs "614' and its make contact, througlrthe start 1 conductor, through break-contacts 1024 through "thestart 2 conductor through t'h e'break contacts o1": fa'ult'release'key 261, through break contacts 25.4,through the winding of relay 204 to grounded battery. Relay 204 energizes over the above traced circuit and at spring 242 closes a circuit from ground through springs *242, spring 235, and its break contact, through the winding or relay 201, through spring 232 and itsbrcak contact through the wiper 223, now assumed to be in connection with the bank contact to'which private conductor 451 is connected, over conductor 451 through the winding of relay 806 or" the director to grounded battery. Relay 806 ofthe director and relay 201 01 the test director selector energize over/his circuit, the former to start the interrupter relay 811 of the a director mechanism, and the latter to seize the director, and to connect it torthe test mechanism.

Sez'ein-g tlredirector.

Relay -201 upon energizing at spring 232 and its make contact puts direct ground upon the private conductor 451 leading to the director C, and making that director busy in the banks of the director selector. At springs 230, 231, and

-233, the relay 201 closes a circuit connect- -'tor 449, through the wipers "221, springs 231,

through the upper winding of relay 205, to grounded battery. Relay 205 energizes over the above traced circuit and at springs 244 closes a circuit from ground through spring 260 and its break contact through

spring

244 and 244,-through spring .246 and its break contact, through the Winding of rela'y 206 to grounded battery. .Relay 206,

upon energizing at springs '248 and 247,

ground potential on through relay 501,

closes a point in a 'circuit through the pulse Wire and release "test wire, respectively, without effect at 'thls time inasmuch as the conductors areheld open in theitest setup control. Relay 206 at spring 245 closes a circuit between the start 1 conductor and the sender start conductor thereby closing a circuit from ground at spring 614 and its make contact over start 1 conductor through springs 245 to the sender start conductor, through springs 332, through the winding of relay 304 to grounded battery, vwith a vparallel branch leading over the hold 2 conductor to the terminals o1 .relays523, 525 and527 ot the sender digit vcontrol. Relay 304 energizes over this circuit andprepares the test sender for impulsing. rupter springs 325 atthepresent timeiare shortcircuited by means o'f the springs 332,

The" inter- V a circuit being traceable from the make contact at sarim 332 throu h ke ,s* rin s 323 l s s y 1. e

and its break contact, through interrupter springs 325, through-key 'sprmgf322 and its brealn contact, vthrough normally closed con- ;tacts controlled by spring 334.,to the main spring 332. V r i The tcszf'semler impulsingi,

Vhen the relay 303 energizes in 'themanner hereinbefore describedfit. closes a circuit from ground through the sender start conductor, normally closed contacts controlled by spring 334, through spring 327 and itsbreak. contact through spring 330 and its break contact conductor 340 s rin 531, through the Winding of relay 500 to grounded battery. Relay 500 energizes over the circuit and at. spring 530 locks itself to the holding conductor 543 in series with relay 501. The relay 501 doesnot energize at this time for the reason that there both ends oi its windone being traceable from mg, ground grounded spring 331 and its break Contact,

conductor 343 and the other. ground through spring 530- to the circuit just traced for relay 500. V] hen the armature 302-01? theinterrupter relay 301 short circuits that relay, relay 303 ei-rergizesand at spring 327 opens the energizing circuit (if-relay 500 which 15 locked in series witl relay 501.

Relay 501 then energizes over a circuit troin ground through holding conductor 343 through spring 530, re-' lay 500 to grounded battery. Relay 501,

upon encrgizingcat springs 532, closes a circu t from ground through said springs through conductor 341, through thewinoing or relay 306 to battery. Relay 306 energizes over the above traced circuit and at spring 332 opens the previously traced circuit-for relay 304 and removes the short circuit "from theimpulse 'spri-ngs .325 ofthe interrupter relay 301. The sender mechanism is-now in position to send out the first'digit of the called number, that digit being determined by the sender IDF jumpering and controlled by the test set-up

relays

601 and 602 The sender impulses into the director.

It will be noted that the first impulse sent out by the interrupter relay 301, atte'rthe sender ground has been received by the test sender, is absorbed in the relays 500 and 501, the secondv impulse being the first one that is effective to control the digit registers of the director. The reason for this is to make sure that the impulses sent in to thedirector are standard, by absorbing the first three'impulses in relays 500 and 501, the possibility of a short impulse is entirely removed. Relay 301 by short circuiting itself to allow relay 303 to energize as has been previously explained, closes the springs 325 in the Well known manner, closing a circuit from ground on sender start conductor through key spring 322 and its breakcontact, through spring 325, through spring 323 and its break contact, through the winding of relay 304 to grounded battery. The relay 304, which was energized over a circuit including springs 332 is held energized over the circuit just traced, that circuit being completed before the springs 332 are opened. When the relay 301 deenergizes it breaks at springs 325 the above traced circuit of relay 304 allowin that relay to restore, closing the circuit which is traceable from grounded spring 532 over conductor 341, through spring 328 and its break contact over the impulse conductor, through spring 259 and its break contact, through springs 230, through the Wiper 220 to the impulse conductor 452, through the Winding of relay 702' of the director, through the wiper 719 and the primary oflice register motor magnet 909, to grounded battery. The relay 702 and the motor magnet 909 energize over this circuit to register the impulse in the director mechanism in the well known manner. When the relay 301 reattracts its armature, relay 303 deenergizes closing a circuit from grounded sender start conductor through spring 327 and its break contact, through spring 330 and its break contact, conductor 340 through spring 531 and its make contact, spring 534 and its break contact, through the Winding of relay 502 to grounded battery. Relay 502 energizes over this circuit and at spring 533 prepares a locking circuit for itself in series With the relay 503. Relay 503, however, having ground on both ends or its coil does not energize at this time. When the armature 302 of the pulsing relay is attracted it closes springs 325, thereby closing the previously traced circuit for the relay 304, which energizes and opens the previously traced circuit of the relay 702 and the motor magnet 9090f the director mechanism. The motor magnet 909 falls back When its circuit is open, but the relay 702 being slow acting because of the copper slug on its core, remains in its-energized position during impulsing. .Vhen the relay 301 has again shunted itself out, relay 303 energizes and at spring 327 opens the previously traced circuit of relay 502 thereby removing the ground from one terminal of relay 503, permitting that relay to energize over a circuitfroin grounded holdingconductor 343 through relay 503 through springs 533, through the Winding of relay 502 to battery, locking up the relays 503 and 502. Relay 503' closes the springs 535, which test the first impulse pin 1 of the sender IDF to see Whether or not the first digit to be dialled is a 1. The test set-upA is arranged to transmit the digits 431, so that the first digit to be transmitted is a 4. The impulsing relay again opens the spring 325 to send another impulse of ground to the motor magnet 909 of the director and to permit the relay 303 to again deenergiz e to send an impulse of ground to the magnet groups 504 and 505, counting 0a the second impulseof the digit.

End of first digit.

jumper 1"" on the sender IDF to the fourth impulse pi-nfthrough spring 544 and make contact over conductor 342, through the Winding of relay 305 to battery. Relay 305 energizes over this circuit and at spring 329 closes the obvious holding circuit forthe pulsing relay 304,.which remains energized and at spring 328 holds open the impulsing circuit to the director thereby preventing the sending of further impulses to that mechanism. The operation of relay 509 to close spring 544 also projects the ground previously traced from the spring 571 to spring 544' over a path including the digit cutoff conductor to spring 570 and through its break contact, through the winding of relay on both ends of its coil in the manner similar to the second relay of the impulse countgroup. Relay 305 upon energizing locks itself to ground through spring 331 and its makecontact, through springs 333, through 1 relay 601, to the sender pin 1", through impulse counting: relays relay 305'todgro1uided battery. Relay 305 upon energizing at spring 331 interrupts the energizesafter an interval, removing ground from. conductor- 012 by the retraction of springs 3133.v Ground being removed from the digit cutoff conductor 342 relay 527 is no-longer short circuited and it energizes in series with relay 526, locking itself in energized positionito the hold-2 conductor ground; vThe restoration of relay 306 re closesthe springs 332: toshort circuit the interrupter springs 325, to maintain the relay' 304eenergized after relay 305 has restored and opened springs 329. The restoration of" relay 305 also completes at Springs 330,, the previously traced circuit to, relay 500,, controlled through springs 327 of therelay 303;

' Thejnext impulse sent by the sender is absorbed, inqthe relays 500 and 501 hereinbefore explained, relay 501 upon pulling'up closing a circuit to spring 532 to the wind ing of relay' 306 to remove the short circuit from the impulse spring 325 to allow impulses to be. sent to the/pulsing relay 304 as previouslydescribed.

Sending the second digit.

Whenwthe relay 527: energizes, at spring 571 it removes the ground from the first digit wire which has been previously traced through the sender IDF to the impulse counting pin 4,. and closes circuit traceable from ground through: spring 571 and its make contact, 568 and its break contact, digits pin 2 through the sender IDF and spring 612, of the relay 601,. through the second digit sending pin 2 of the sender IDF and thence through the jumper to the third impulse pin, which is connected through the spring 541 to the digit cutoff wire; The set-up determines that the second digit transmitted by the test sender is to bear 3;, In. the director, at the end of the transmitting; of the first digit, therclay 702 deenergizes after a'brief interval and close circuits by meansof which the wiper 719 was transferred from the first bank contact to the second, thereby changing the circuit so that the secondset of impulses will be delivered to the secondary office register motor magnet 910 rather than to the magnet- 909, The transmitting of the second digit bythe test sending equipment into the director duplicates the'process just described 1 in connection with the first digit and need not be explained in detail. At the end of the transmitting of, the second digit, the ground rector.

is supplied to the digit cutoff conductor when the springs 54,1 areenergized after the third impulse, and the digit controt relays 524 and 525 energize in a manner similar to that described for relays 526 and 527, transferring the digit cutoff ground from the second digit conductor to the third digit conductor, supplying that ground-over the obvious circuit including spring 611 tothe first impulse spring then to, the springs 535 of the impulse counting relay 503. In the director at the end of the second digit the relay 702 de- 7 energizes for a brief interval and causesthe 747m" J ,h'1b'k wiper (19 to be moved to the t -ro an con 7 tact thereby completing the clrcui-t so that. the third digit received. by the director will be transmitted to the first digit reg ster, in the manner explained in detail 1n my first above mentioned copending application;

' Transmitting the digit.

The sending mechanism having completed v sending the second digit, restores the countingrelays to normal, and restarts the impulse sending,eis in a position to send out the last digit of the call number 431, inthis case a 1. The sending of the 1.is identical 5 with the sending of thepreviously explained digits and need not now be. described,

Sender cuto f;

spective makecontacts over the fourth digit control wire 4, which is jumpered to; pin 4 and connected through spring 610 to pin at", through the jumper to the stop conductor, thence over the stop conductor, through relay 307 to grounded battery. Relay 307 energizes and at springs 334: opens the start ground circuit to the impulse sen-ding mechanism, thereby removing ground, which was suppliedt-o the test sender over thesender start conductor, from the sending. mocha-7 nism, definitely preventing the sender from transmitting any more impulses tothe di- Itelay 307 upon energizing locks itself to the grounded sender start conductor over spring 334- and its make contact, thereby holding itself in energized .position independent of the grounded spring 571. Re-

lay 307 upon energizing removes the ground from the hold 2conductor, thereby unlockring the energized relays of the digit control group, restoring them all tOr'llOl'lllfll in readiness fortransmitting of the nextnumber by the sender.

The director starts impulse/Lg. The director outgoing loop circuit now' connected to the relay 205 over acircuit ineluding the spring 854 of the director mechanism, also includes a parallel circuit includ ing conductor 449 to interrupter spring 813, thence back to conductor450. When the director is in position to transmit the-first digit the short circuit of the interrupter springs 813 by the springs 854 is removed and the springs 813 begin opening the loop circuit of relay 205, causing that relay to impulse and send out the iirst digit. vAt the end of the first digit the springs 856 are closed to stop the impulsing by again short circuiting the impulsing springs, in the well known manner that is explained in detail in the first of my above mentionedcopending applications. In the test director selector the relay 205 upon falling back opens the previously traced circuit of relay 206, with out effect at this time owing to the fact that relay 206 has locked itself to ground over its circuit from grounded key spring 239 and its break contact, through springs 238,. through hold 4 conductor, through spring 246 and its make contact, through the winding of relay 206 to grounded battery. Relay 205 upon falling back also closes a circuit from ground through spring 260 and its break contact, through spring 244 and its break contact, through springs 248 to the pulse conductor, through spring 764 and its break contact, through the Winding of relay 712 to grounded battery, with a parallel branch, through spring 1045 to conductor 775, through spring 763 to the test relay conductor, thence through the winding of test relay 207 to grounded battery. Relays 207 and7l2 energize over this circuit, the latter spring 752 forming a locking circuit for itself in series with the relay 701, which is connected to the grounded hold conductor. Relay 701 does not energize at this time-for thereason that the ground on the pulse conductor short circuits the relay. Relay .207 upon energizing at spring 250 closes acircuit'from grounded start conductor through the fault release key 261, through spring 254, spring 250 and its make contact to the winding of relay 209. Relay 209 upon energizing locks itself to the fault release conductor through spring 253 and spring 258, independent of the spring 250. At the end of the first impulse the relay 205energizes again opening the previously traced circuit to relays 712 and 207. Relay 207 being slow to release because of the copper slug on its core, remains energized during iinpulsing.

I l Vhen the round is removed from the ulse wire, relay 701, which was short circuited by that ground is no longer short circuited and energizes over a circuit from the grounded holding conductor throughrelay 701 through springs 52, through the winding of relay 712, to grounded. battery. Relay 701 upon energizing extends the pulse wire to relays 702 and 713, and extends the explained, the second impulse Will lock up,

relays 702 and 713 in a similar manner and the third impulse will lock uprelays 703 and 714. The fault conductor will now be connected through

springs

730, 731, and '7 32 and their respective make contactsv to springs 7 33, and the lamp ground will be connected through

springs

741, 742, and 743 and their respective makev contacts to the springs 744, and the pulse wire will be connected through springs 764, 765, and 766 and their respective make contacts to the springs 767.

Testing the digit received.

' lVhen the spring 856 of the director short circuits the interrupter springs 813, the re lay205 comes to rest energized, opening the circuit oftest relay 207, which restores after a brief interval and closes the test circuit,

.which may be traced from grounded start conductor through the fault release key 261 and thence over the previously traced circuit to the spring 250, which is now resting against its break contact, through the springs,

255, and thence over two paths in parallel, the one through the Winding-of

relays

211 and 210 in series to grounded negative battery, and the other over the fault conductor,

which has been traced to spring 733 now resting against its break contact through the third impulse Wire of the receiver IDF, now jumpered to the first digit pin 6, through spring 617 and its make contact to the first digit pin '1 through the jumper to digit pin 1, thence over the digit 1 conductor to springs 822, through spring 822 and its break contact to the test conductor, through the receiver IDF through spring 616 and itsv make contact to the junction point between relays .210 and 211. The impulse having been correctly received, relay2l1 is now short circuited, ground being present on both terminals, and that relay therefore does not energize. Relay 210, energizes over the circuit just traced including the test conductor and at springs 268 opens the locking circuit of relay 209, allowing that relay to restore. Simultaneously with the establishment of the just described circuit to relay 210 ,a parallel branch is established from the digit 1 conductor through springs 821 to the winding of relay 805 to grounded battery. Relay 805 energizes over this circuit and at springs 824 prepares a locking circuit foritself in series with relay 801. Relay 801 being short circuited at this time by having ground po tential on both terminals is prevented from its make contact to the second digit control wire to spring 827. Relay 209 upon deenergizmg at springs 256 breaks the holding circuit for the receiver impulse counting relays 701 to 714, which were energized and locked to the hold conductor in counting oifthe first digit, thereby restoring the test set to normal in readiness for the reception of the second digit which in this case will be a 4.

A fault on the first digit. In the event that the director had failed to send out a 3, for the first digit of the call number, when the test relay 207 energized and the fault and test circuit was established, the relay 211 would not have been short c-ircuited for the reason that the fault wire would not have been connected to the test wire over the loop circuit previously described. Assume for the moment that the director had sent out a 4 for the first digit instead of a 3. The fault wire would have been connected through springs 733 and its make contact to the springs 734 and its break contact to the fourth impulse pin on the receiver IDF, and the lamp ground conductor would have been connected to spring 7 44 and its make contact through the spring 745 and thence to the digit lamp 4. The fourth receiver IDF impulse pin, being multipled to the second digit control wire I instead of the first, would have caused the receiving of the digit 4 as a first digit to be registered as a fault, for the reason that the test circuits which were. traced through spring 822 and its break contact to thedigit 1 conductor would not have been connected to the fault wire, since the relay 704 would have been energized by the last impulse of the digit and the contact 733 would be made instead of broken. Therefore the relay 211 would not be short circuited and would energize in series with the relay 210. The relay 210 being marginal will not energize in se ries with relay 211. Relay 2 11 upon cnergizing, at springs 260 opens the ground circuit to the impulse springs 244 of the relay 205, thereby preventing the impulsing relay 205 from having any effect upon the receiving mechanism. The spring 260 clos-- ing a circuit to its make contact closes a circuit from ground to the lamp ground conductor which is prO ected through springs 741, 742,743, 744, and'745 through the" fourth impulse lamp to battery. With a.

branch circuit through spring 615 and its make contact, through the lamp ground conductor 2, through spring 833 and its break contact, through the digit lamp 1 to battery. The relay 211 upon energizing further closes a circuit from ground through.

resistance 262, through spring 259 and its make contact through the impulse wire leading to the director-" A circuit is completed I through the grounded resistance 262, spring 259 and its make, contact, impulse wire I through relay 702 of the directoiythrough' wiper 719 now in engagement with la'st digit reg1ster, through the magnet of that register to grounded battery. The relay 702-energizes over this circuit thereby preventing the d1rector from cuttmg off. The high resistance of 262 preventsthe digit register motor H magnet from energizing in series with that resistance and relay 702. The director proceeds to impulse the remaining digits .of the call number, but since the ground has re-' moved from the impulsesprings 205,.this

The lampimpulsing is without effect. ground conductor is; further. multipled to the audible signal 412, which sounds to call the attendants attention to the fault. The

grounded lamp conductor has lighted the fourth impulse lamp, the first digit lamp,

and sounded the audible signal calling the attendant to the test set-up, who will investigate the trouble. The attendant will note the director being tested, that being indicated by the director number lamp which is lighted from the grounded director selector wiper 222 through the obvious ,circuitto the Inc recordchart, giving the correct number for test set-up A and will note that the first digit should have contained three impulses instead of four. The ground placed on the impulse conductor by the fault relay 211, prevents the director from cutting oil and releasing itself from the test set, and furthermore prevents the director from restoring to normal so that the attendant will find the director set just as it was when it sent out the faulty digit.

The attendant upon.

finding the trouble with the director, will repair the trouble, and if he desires to exercise that director, will operate the key springs 241 to cut off the director selector motor magnet thereby permitting him to ex; ercise the director in a manner which will be explained hereinafter. Having repaired the director, the attendant operates the faultrelease key 261, removing ground from the re-.

nae