US1586587A

US1586587A - Testing system for testing subscribers' station apparatus

Info

Publication number: US1586587A
Application number: US723804A
Authority: US
Inventors: Carleton V Taplin
Original assignee: American Telephone and Telegraph Co Inc
Current assignee: AT&T Corp
Priority date: 1924-07-02
Filing date: 1924-07-02
Publication date: 1926-06-01
Anticipated expiration: 1943-06-01

Description

June 1 1926. 1,586,58 7

C. v. TAPLIN TESTING SYSTEM FOR TESTING SUBSCRIBERS STATION APPARATUS Filed July 2, 1924 3 Sheets-Sheet 1 S y Q v y Zub-fi:

June l 1926. 1,586,587

C. V. TAPLIN TESTING sTsTEM EoR TESTING suEsoRTEEEs STATION APPARATUS Filed July 2, 1924 A3 sheets-sheet 2 N HUH) June l 1926.

C. V. TAPLIN TESTING SYSTEM FORv TESTING SUBSCRIBERS STATION APPARATUS V 5 Sheets-Sheet 3 Filed July 1924 Patented Juneil, 1926.

,UNITED y; STATES lef-.dureNT oFFlvcs.

CARLETON v: TAPLIN; or EAST ORANGE, uEwjJnRsnY, AssIeNoR 'roAMnRIoAN TELEPHONE AND ''riinnen-APH` COMPANY, A CORPORATION or' NEW YORK.

.TESTING SYSTEM FORk TIESTJJ'Gy SUBSCRIBERS STATION APPARATUS.

Application filed Iulyf 2,

This invention relates to an automatic telephone exchange system and more partie ularly to a testingsystem` for testing subscribersl vstation apparatus.

Itis the Object ofthis invention to vide an improved testing system. i

Thisinvention Vis especially directed toward the provision of testing equipment in an automatic central Otlice for use by a man repairing an unstandard subscribers station associated `with a line extending from that central office'. j

Heretofore it vhas been the practice for Va man who has made adjustments at a subscribers station to dial or call a special Operator at the central olice andy request that a call be directed to said subscribers station. This method of testing requires manual assistance at the central office, `also the usual period of time consumed in making the manualftest is greater than in a test that is automatically responsive.` C

lt isftherefore lthe purpose of this invention to provide improved automatic testing equipment at the central office that may be lproselected` by ordinary means from a subscrib- In response to the selection ofl ers station. this testing equipment, a test is made of the subscribers station apparatus.`

A feature of this invention 'is in the use of an` automatically operable testing device to test subscribers station apparatus in re subscrlbers stasponse to a call from that tion.

A further feature of the invention relates to progressive meansfor the control of the application of ringing current to variously adjusted subscribers station apparatus i'n response to call from said subscribers station. c y

These and other features of the invention will he apparent from the following description taken in connection with the accompanying drawings.

lVhile theinvention has been disclosed as particularly adaptable for Ausewith panel 1924K. Serial No. 723,804.

Fig. 2`illustrates a district selector switch used to associate the subscriber7s-line with the .automatic testing circuit shown in Fig. 3.` Fig. also illustrates a sender ink diagram form associ atedwith the district selec` tor switch. f

.Figy 3 illustrates the testing device arranged to hold the district selector in a given position so that tests may be applied to a calling subscribers station.

Fig. i illustrates the manner in which the drawings of Figs.r 15 2 and 3 should be associated.`

' Description of apparat-us.

4 switch andyrelays of welliknown types.

, i General description.

Letitbe assumed that a repair man is making adjustments or repairs upon the apparatus of a subscribers station associated with a line extending from an automatic central Oiiice. After the completion of adjustments or repairs, it is the usualr practice to test the subscribers station vapparatus by requesting ka call from a desk operator at'thecentral otlice. According to this invention7 the testing apparatus at the central office is automatically responsive to test subscribers station apparatus from which a callgis initiated, independent `of manual assistance at said central office. n

The man at the subscribers station dialsk a. code'specied for bell testing, in the normal manner of' initiating a call, with the eX- ception that the numbers are omitted that are ordinarily usedvfor associating selector switches with a distant line.'y The code registers of the sender are set to direct the' distri-ct selector shown in Fig. 2 to a trunk` associated with the automatic testing device shown, in Fig. 3. When the district seleclos tor is advanced to a. particular position known as an operators talking position, a suitable tone is connected to the line by the testing device. rJhe purpose of the tone is to signal the man at thel subscribers station to dial a

number

1, 2, 3 or 4 to indicate the type of ringing currentto be used for ringing the bell. Then this number has been dialed, the receiver is restored to the switchhook, which action causes the testing device to automatically posit-ion itself to associate ringing current of thei correct potential and polarity with the line. It the bell rings in the proper nia-nner, the test is concluded by the removal of the receiver from the switchhook to trip the ringing control apparatus of the testing device. VVhen the receiver is again restore-u to the switchhook, the testing device and district selector are released and automatically restore themselves to normal.

Detailed description.

Let it be assumed that a repair man, located at subscribers station B to make repairs or adjustments, Wishes to test the subscribers station apparatus. The receiver is removed from the switchhook to initiate a. call to the central otlice and a circuit is thus established to operate line relay 101 of the switch 100. This circuit may be traced from grounded battery, through the right winding of relay ,101, the innermost lower contacts ot cut-off relay 102, over the line conductor 103 through the substation ap-` paratus of subscribers station B and thence over line conductor 104 to ground at the upper contacts of cut-oil' relay 102. The operation ot line relay 101 establishes a eircuit to operate the stepping magnet- 105 from grounded battery, through the winding and contacts of magnet 105,l conductor 106, the lowermost contacts ot relay 1021 right front contact-s of relay 101, conductor 107, and thence to ground through brush 108 and its associated contact. The magnet 105 upon energizing in this circuit, advances brushes 108 to 113 inclusive ol switch to the second contacts to which they have access. As the second contact' associated with brush 108 is permanently connected to ground, the magnet continues to step the brushes to the third set ot contacts leading to the first of a group of trunks to which the switch 100 has access;

It' the first trunk of the group is busy, there will be a ground potential on the test terminal thereof, appearing in the lowermostbank oi the switch and the switch will, therefore, continue stepping until an idle trunk is found. An idle trunk is characterized by grounded battery. When this battery is encountered, a circuit is established through the right contacts of sequence svitch cam 202, of the district selector to which the first idle trunk extends, through the inner lett normal contacts of relay 226, test conductor 114, brush 10S and its associated contact, conductor 107, left contacts and lett winding ot relay 101, conductor and thence to ground through both windings oiu the cut-ott` relay 102. The energization et the cut-oli' relay 102 in the circuit traced opens the energizing circuit for the steppingl magnet 105 to arrest the rotary movement of the line switch. Line conductors 103 and 101i are vnow extended from the subscribers station B through brushes 111 and 113 to the trunk conductors 11G and 117 leading to the selected district 30 selector. The operation of relay 102 further establishes a circuit to operate relay 226. This circuitmay be traced from grounded battery, through the right winding of relay 220,-left normal contacts ot relay 227, right lower contact ott cam 203, sleeve conductor 11S, brush 109 and its associated contact, conductor and thence to ground through the lower intermediate contacts and upper winding of cut-oil1 relay 102.

The calling subscribers line is made bus)v to calls incoming thereto by the connection of battery potential to terminal 121 of the calling line appearing in the banks ol all final selector switches having access to this line over brush 110.

Upon the operation of sleeve relay a circuit is established to operate relay et the district selector. This circuit may be traced from grounded battery through the right winding ot relay 228, lower right coii tact ot cam. 204, conductor 220, lower contacts of cam 205, conductor to ,ground through the right alternate contacts ot relay 226. The operation et relay further sociates ground over its inner lett trout cti tacts with the test conductor 1141-, of the se lected trunk to mark the trunk bus).Y to other line switches and at the back contact ot this same set of relay contacts disconnects the source of battery potential which up to this time marked the selector switch as idle. Line relay 101 is now deencrgized.

Relay 228 upon energizing establishes a circuit for rotating sequence switcn 200 from its normal position 1. to position 2. This circuit extends .trom grounded battery through the winding oi' magnet 200, conductor 231, left upper contact ot cam 206, rig-'git inner contacts of relay 228 and thence to ground at the right lower contact ct c 207. In sequence switch position 2` a ci. cuit is established to operate relay 227 'troni grounded battery through its winding, lett upper contact ot cam 208 to ground. The operation of relay 227 establishes a locking circuit tor the sleeve relay and cut eil" relay 102 extending from grounded battery through the right winding ot relay 220, iei't contacts ot relaj." 22" and thence to the sleeve conductor` 118 over the right upper Contact of cani .203 to ground'through thel contacts andV- uppervwinding ot relay 102. This circuit is lmaintained throughposition 16 lof the sequence switch or until relay 227 becomes deenergized In' sequence yswitch position 2 a 'further circuitis established to associatev a new` holding ground-,with test conductor 114 extending `over conductor 232 andthrough the rightupper Contact ot cani 208 which is maintained through position 181/4 of the sequence switch. r w i As soon as the sequence switch reaches poe sition 1%, during itsrotatioirfrom position 1 to position 2, a circuit is established for energizing stepping lmagnet 233 `ot the sender finder switch. 'This circuit maybe traced from grounded battery" throughk the contacts and winding ot magnet 233,--left upper contact of cam 209, conductor 234,* to groundlthrougli the right innercontacts of relay 228 and right lower contact of cam 207. `A circuit is further establishedfroin grounded battery through the contact and winding of magnet 233,winding -offcutin vrelay 235 to groundat the lett lowercon'- tact of cam 208. Relay 235 does not'energize at this time since its winding is shunted by ground connected tothe armature of relay 228. "i f Y- Upon the rotation of sequences'witchf200 out of position 1 1the initial energizing circuit for relay 228` `is yopened at the right lower contacty of cani 204. kA holding cijrcuit is,however,` established'foiier a circuit extending from grounded batterythrough its leftwinding and leftcontacts,` left upper contact ofl cam 210, rightv lower contact of cam 211, conductor 237, brush'238 ofthe sender findery switch andto groundv upon' the busy contacts associatedwith brush 238 suniing that the first contacts encountered by brush 238 are busy.` When an idle sender is associated with 'brush 238 tlie'terminal is not characterized by a ground thus opening the holding circuit for relay'228 to cause its release. The release of relay 228 opens the venergizing circuit for the stepping magnet 233 and establishes at Vits right innercontacts a circuit to rotate'sequence switch 200 from position 2 `to"position 3. The circuit for rotatingj thesequence switch may be traced from grounded battery through the magnet 200,y conductor 231, right upper contact of cani 206. right inner contacts of relay 228 to ground at the right lower contact vof cam 207 f f l p The deenergizationfoi relay' 228 removes the shunt around the winding of yrelay 235. Relay '235 thereupon energizes in series with stepping magnet 233 the winding ot magnet 233 is not suilicientv to cause yits energizatio'n.y The operationof relay 235 'establishes a circuit from ground over the circuit pre` viously traced. The current flow through through Aits vleft innerfcontacts, brush` 238 and associated contact to operate 'certain apparatus of the sender as described in Patent No. 1,395,977 to Franklin Frederick J. Scuddei. y

Upon the operation oi certain ot the sender apparatus the dial tone is associated with the calling subscribers line B Ito `indicate to the calling repair man that the apparatus ot the central oilice is preparcdto receivethe dial interruptions. To control the sender t. Stearn and in vsuch. manner that the district selector switch is associated with a trunk connected tothe testing device, Fig. 3, the repaii man dials a'particular codetliat will set the A and B coderegisters of the sender .in afpar-y y ticular manner, to` set they translator .for driving the? district selector switch rto terminals1260f259 and 258'associated witliftlie testing device. vThe numerical registers ot the sender are not vset since the district se` cuit to rotate Lthe sequence switch, Fig. 2, `1

from position 3 to position 4. This circuit may be i traced from grounded battery through the 4winding of magnet 200, left upper contact of cam 206, righty inner contacts of relay 228 to ground through the 5 right lower contactof cam 207.

lith the sequence switch, Fig. 2, in position 4, brush selection-is made by the establisliiiieiit oi` a circuit `for updrive magnet 245xfrom grounded battery through the winding of magnet 245, right upper contact of cam 209, conductor'234 to ground through the right inner contacts of relay 228 and right lower contact of cam 207.` Updrive magnet 245 upon; energizing causes the upward movement ot the switch shaft, whereupon brush 252 engages commutator 249 and intermittently establishes a shunt' circuit to intermittently release-the stepping relay ot the sender. Relay 228 remains operated during -the upward. movement of the selector switch shaft from grounded battery through its lett winding and coiitacts,left upper contacts ofcain 210. inner right contacts of relay `235,.brush 244 to ground throughtlie sender stepping relay. f n

`Vlien'the counting relays in the sender have been operated in accordance with the setting of the translator switch, the fundamental circuit isopened to open the operatgie ing circuit for relay 228 and; the stepping. re lay of the sender. Relay 228 opensthe energizing circuit for updrive magnet 245v and thus arrests the upward' movement of the selector switch shaft. The release of relay 228 further establishes a circuit to rotate the sequence switch, Fig. 2, from position 4 to position 5. This circuit extends. from grounded battery, through the winding of magnet 200,. right upper contact of cam. 206, right inner contacts of relay228wto ground at the right lower contact of cam 207. The sequence switch, Fig. 2 now in position 5, again establishes the fundamental circuit previously traced to operate relay 228 in serieswith the stepping relay of the sender. rlhe operation of relay 228 establishes. af circuit to rotate the sequence switch, Fig., 2, from posit-ion 5to positionG. lVhen the sequence switch rotates out of position 5 the initialr energizing circuit for relay 228 is replaced by a holding circuit through its lett winding and contactsv as previously traced.

Upon reaching position 6v district group selection is made by the establishment of a circuit as previously traced to energize the updrive magnet 245. In positions 5 and 6 of the sequence switch an obvious circuit is established to energize trip` magnet 253. Upon the energization of the updrive mag net the trilnningspindle 292 has therefore been rotated to a position to trip the brushes 263, 26er and 257 upon the upward movement of the selector switch shaft andduring-the continued upward movement of the switch shaft the brushes travel over the contacts ot the banks with which they are associated. During the upward movement of the switch shaft, brush 256 intermittently engages the conducting and non-conducting portions ot' coinmutator 255 anc thus intermittently establishes a shunt for the stepping relay in the sender in the same manner as for diS- trict brush selection. In this manner when the stepping relay has been released and operated a suiiicient number oi times to operate the counting relays of the sender, the Jfundamental circuit is again opened, to release relay 228 and release the stepping re ley of the sender. The release of relay 228 opens the energizing circuit for updrive magnet 24:5 and thus arrests the upward movement of the district selector switch shaft. The release of relay 228 further establishes a circuit to rotate the sequence switch, Fig. 2, from position 6 to position 7. In sequence switch position 7, a circuit is again established to energize relay 228 from grounded battery through its right winding, right lower contact of sequence switch spring 20st, conductor 229, lower contacts of cam 205 to ground at the right contacts of sleeve relay 226.` Relay 228 upon energizing establishes a circuit to4 rotate the sequence switch, Fig. 2, from position, 7to position8., This circuit may be traced from grounded battery through the winding ot magnet 200, conductor 231, left upper contact of camA 206, right inner contacts of relay 228, left upper contact of cam 207v to ground through the right contacts of relay 227.

Thesequence switch, Fig. 2, upon rotating out of position 7, opens` the initial energizing circuit for relay 228, but this relay, however, remains energized over a locking circuit which may be traced from grounded battery through its left winding and left contacts through the left upper and lower contacts of cam 215, right outer contacts ot' relay 228, lower contacts of cam 222, test brush 257 to a ground if a busy testing device isv encountered. A plurality of these testing devices are associated with adjacent terminals and it may be necessary for the district selector switch, Fig. 2to hunt for an idle one. A busy trunk to a testing device is characterized by a ground through the Winding of relay 321, contacts of relay 322, contact of cam 308 to terminal' 258. Upon reaching position 8 with relay 228 energized, a circuit is established tor the updrive magnet 245 which may be traced from grounded battery through the magnet 245, right upper contact of cam 2.09, right inner contacts of relay 228 to ground through the right. lower contact oi' cam 207. The updrive magnet 245 upon energizing drives the switch shaft upward in search of an idle trunk extending to a testing device. The selector switch shat't continues in its upward movement' until the. terminals of an idle testing device are encountered. `When. an idle trunk is encountered which it will be assumed is the trunl; terminating in

terminals

258, 259 and 260, the locking circuit for relay 228 is opened to cause its release. Upon the release ot relay 228 the energizing circuit for up'drive magnet is opened to arrest the upward movement of' the district selector switch shaft and a circuit is established to ,rotate the sequence switch, Fig. 2, from position 8 to position 9. Upon reaching position 81/2 a busy ground is connect-ed to the multiple testing ter minals of the selected trunk over brush 257 and the right contacts of cam 215.

An energizing circuit is again established for relay 228 upon the rotation of the sequence switch, Fig. 2, to position 9, from grounded battery through its right winding, right lower contact of cam 204, conductor 229, left lower and right upper contacts of cam 205 to ground at the right contacts of relay 261. Relay 261 is at this time energized over a circuit extending from grounded battery through its winding, left upper Contact of cam 216, right outer contacts of relay 235, right lower contact of cam 217, brush 262 and its associated contact to operate relay 228.

resets? 'groundat the sender. Relay 228 upon en-` ergizing in the `circuit traced establishes ai circuit to rotate the sequence switch, Fig. 2,; from position9 to position 10.

During the control oi' other switches for an ordinaryservice connection, the Idistrict. selector switch remains in position l() and the ofce. selector. switch, incoming selector switch andvffinal select-or 'switch are posi-y tioned in accordance with `the setting otthe numerical registers of the loffice sender.

Upon the completion of the setting of these selector switches a reversal of'current flow is made in the incoming .selector switch toadvance the district selectorswitclnFig. 2,'and thebice sender. Since in selecting this testing device it is notnecessary to controll other selector switches Ithe reversal ofcurf rent tlow'is :controlled by the 'testing device as soon as thedistrict selectorswitch, Fig. 2, rotates its sequence `switchto position 10. -Thiscircuit may be tracedytromejgrounded battery through thewinding of relaye325, right contact. of cam` 307, terminals 260, brush 263,. right upper and left lower contacts of cam 218, right inner contacts otre lay 235, brush y24A andits associatedicontact and thence overthe, fundamental circuit of the oice sender through the stepping andy which releases .and establishes a circuit to` rotate the sequenceswitch, Fig.2, from posi-` tion c10 toposition 1l. `This circuit may be traced from grounded battery, through thewindingy of magnet 200right uppericontact offca1n..206right inner normal contacts of relay 228 to ground through the rightlower contact of cam `207. Insequence Switch position 11a circuitis establishedthrough the apparatus-of the oiiice sender to again ThisY circuit may be traced from grounded battery, through the left winding rof .relay 228, right upper and leftlow-er contacts ofcame2l0, righty inner.

contacts of relay 235 brush 244 and its associated contact to ground through .the

sender apparatus. The operation of relay 228 establishes an energizing circuit for sequence switch magnetf20() from. grounded battery through the win'dingrotthis magnet,

left upper contact offcam-206, rightinner contactsof relayg228 to ground through the right' lowerzicontact of cam '207. `The sequencefswitch, Fig. 2, is now rotated` from position 11 to position 14e under the control of the oiiice sender.` Wheny the ysequence Switcln 2, has` ,rotated through posi tion 13%the ,holding circuit for relay 228 `isopened by the sender apparatus.- Therelease of relay 228 opens the actuating circuitforsequence switch magnet `200 to ar-V rest. the, sequenceswitch in' position y14e.

Itk ywill' becnoted that/when the sequence' switch, Fig., 2, rotated .out-of position 11, I theoriginal lenergizing circuit for relay 228 wasopened .at thev right upper contact kof sey cam 210. Relay 228 is,fhowever,held oper-` ated Jover a flocking-circuit extending from l grounded batteryrfthroughits left windingf and' left contacts, kthrough the .left .contacts of cam 210, right inner. contacts of relay 235, bnush 1244: and its associated contacts to ground through the associated sender apparatus.

ln. Win be remembered niet reiery 325 wee operated in position *10, .of the sequence` switch, Fig. 2. 'zThe operation of relay 325 establishes .an obvious circuit to operate slow-releasing relay 324;. Alsoa circuit is` established to operate. `counting relay l. This circuit may betraced from grounded battery through the windingr of counting relay l, left normalcontacts ofcounting relay 1f, right contacts of cam 308 tok groundk through the right contacts of relay 325.l LThe operation of ycounting relayl establishes a. holding circuit foritself through the winding of counting relay 1 to ground.

through the right contact of cani 310.v An operating circuit for relay/1 is also established which is not eiiective until the release of relay 325-which removes the shunt ground. Upon thel rotation of sequence switch, Fig. 2, 4out of position l0, relay 325 is released and counting relay 1 is thus operated. Upon further rotation ofthe sequence switch, Fig. 2, a` circuit yisagain established to operate relay 325 which may be traced from grounded battery, through its winding, rightcontactof cam 307, terminal 260,fbrush,263, `upper contacts `of cam218, right upper winding of repeating coil 267, upper contacts of cam220,wind. r ing of relay 268, lower contact of cam 221, v

right lowermost` winding of .repeatingl coil 267, upper contacts of cam 219, brush 264, terminal 259, left contact ofycam 305 to ground through the left winding of balancing,y coil 323. The operation of relaykf325y over the circuit traced establishes an, actuating circuit for 'counting relay 2 from ground through the right contacts of yrelay 325,k right contacts of lcam 308,` contacts of counting relayv l', left `normal contacts of counting relay 2, winding of counting revlay2 tol grounded battery. f Counting relay 'ated position.

2 operates in the circuit traced to establish an actuating circuit for sequence switch magnet 300 to rotate the sequence switch from position 1 to position 2. This energizing circuit may be traced from grounded battery through the winding of magnet 300, left lower contact ot cam 312, right outer contacts ot counting relay 2 to ground through the right contact of cam 310. The sequence switch in rotating from position 1 to position 2 opens the holding circuit for the counting relays to cause vtheir release and 4opens the circuit path extending from the Winding ot' relay 325 to the district selector switch. VThe current which Wastlowing in the circuit as traced through the Winding of polarized relay 268 Was in such direction thatthe yrelay was not actuated.

Upon the rotation of the sequence switch, Fig. 3, from position 1 to position 2, a circuit is established through the windings of relays 325 and 268 over which both relays are operated. This circuit may be traced from grounded battery through the Winding` of relay 325, right contact of cam 305, terminal 259,'brush 264, upper contacts ot' cam 219, right lowermost ivinding'of repeating coil 267, lower contact o cam 221, Winding of relay 268, upper contacts of cam 220, right upper winding ot' repeating coil 267, upper contacts'of cam 218, brush 263, terminal 260, lett contact of cam 307 to ground through the lett Winding of balancing coil 32". The operation oft relay 268establishes a circuit to operate relay 228. This circuit may be traced from grounded battery through the right Winding ot relay 223, right lower Ycontact of cam 204, contacts oi" relay 268 to ground through the lett upper Contact otl cam 21st. The operation of relay 228'establisvhes'a circuit to rotate the sequence switch, Fig. 2, `from position 1*/-1 to position 15. The circuit for energizing magnet 200 may be traced from grounded battery through its Winding, leiit upper contact ot cam 206, right inner contacts ot relay 228to ground through the right lower contact of 'cam 207.

During the rotation o'l the 'sequence switch,

Fig. 2, from position 11 to position 15, the

energizing circuit i'or relay 268 is opened, thus opening the energizing circuit for relay 228. AK locking circuit is, however, established`v to maintain relay 228 in an oper- This circuit may be traced from grounded battery through the lett Winding and lett contacts of relay 228, upper contacts ot cam 215, brush 257, terminal 258, contact Vof cam 303, normal contacts of relay 322, Winding of relay 231 to ground. Relay 321 is operated in the holdingl circuit traced for relay 228. The operation ci relay 321 establishes a circuit to rotate the sequence switch, Fig. 3,`t`ro1n position 2 to position 3. This circuit may be-traced from grounded battery through the winding -ot magnet 300, upper contact of cam 311 yto ground through the contacts of relay 321.

A source of tone current is now associated with the calling subscribers station through balancing coil 323. The primary tone circuit may be traced trom grounded battery through tone interrupter 330, condenser 331, right winding of balancing coil 323 to ground through lett contact ot cani 310. The tone current is induced Jfrom the right to the leit vWinding of balancing coil 323 and is carried over the district and line conductors to the subscriber-"s station so that it is audible to the repairinan controlling the testing device. T he secondary tone circuit may be traced from ground through the lett Winding ot balancing coil 323, lett contact of cam 307, terminal 260, brush 263, con ductor 271, right upper contact of cani 212, conductor 117, brush 113 and its associated Contact, upper contacts of relay 102, conductor 104, through the apparatus of the subscribers station B, returning over conductor 103, lower innermost contacts-ot relay 102, brush 111 and its associated contact, conductor 116, left upper contact ot cam 213, conA ductor 272, brush 264, terminal 259, right contact ot cam 305, winding ot relay 325 to grounded battery.

The tone current transmitted through the subscribers station serves as a. signal to the repairman that the testing device is associated with the line. It is now the duty of the repairman to dial the proper digit to select the character oit'ringing current to be associated with the subscribers station Jfor actuating the'ringer magnet. It a 2 is dialed, the interruptions of the dial cause relay 325 to release and operate twice. The initial release of relay 325 establishes a circuit to operate counting relay 1. This circuit may be traced from grounded=battery through the Winding Votcounting relay 1, lei't normal contactslof counting relay 1', right lower and lett upper contactsof cani 308 to ground through the left contacts of relay The operation of counting relay 1 establishes `a lockingy circuit for itseli and an operating circuit for counting'rela-y 1 which is eiiectiye as soon' as the'shunt'ground is removedby the succeed-ing operation ol' relay 325. Relay 325 again'operates as the dial rotates to close the circuit of the sul scriber's sta-tion and removes the shunt-from counting relay-1. Uponthe next subsequent release ot relay '325, a circuit is established to energize counting relay 2 from grounded battery through its Winding,`lett normal contacts ot' counting relay 2', left alternate contacts of counting relay 1, right lower and lett upper contacts ot cam'` 308 to ground through the"right back contacts of rehy 325. Counting relay 2 establishes a locking circuit for itself andan operating circuit for relay 2 which isefective upon. v

the subsequent andv last operation of relay 325.y The repairman now Irestores the re-v out of position 3. This circuit may be traced `tromgrounded battery through the winding or' magnet 300, `lower left contact of cam 311, contactV of cam .309 to ground through the normal contacts or relayl 324. Upon the rotation oic the sequence switch out of position 3 a shunt isremoved from the winding or" counting relay and -a circuit :tor its operation is eil'ective through the winding and contactsof-counting relay 3. Upon the rotation of the sequence switch into position 4 a circuit is established to further rotate `the sequence switch to position 5. This circuit may be traced from grounded .battery through the winding or magnet 300, rightlower contact or cam 312, right contacts of j countingr'elay 3', contact of cam 309 to ground through the normal contacts of re.

lay 324. .v

During the rot-ation of the sequence switch, Fig. 3,`from position 3to position 5, relay 3,20 is operated so that ringing ,potential is not impressed upon the line until thesequence switchis properly positicned.

The initial actuating circuit for relay 320 may be traced from grounded battery through its winding, lower left contact ofcam 311, contact of cam 309 to ground through the normal contacts of relay 324. During the rotation of the sequence switch from position 3-to position 4, a circuitis established to ground through the contact of.

magnet 300 to hold relay/320 actuated.y

Upon reaching position 4, the energizing.

Circuit Afor relay '320 is again changedand may be traced through theright lower con-v tact ont cam 312, right contacts of counting' relay 3', contactA of kcam 309 to ground though the normal contacts of :relay 324. Then the sequence lswitch has rotated/to position 5, the actuating circuit forv relay 320 is opened to cause its release. Negative ringing current is now associatedV with the tip conductor of the line and ringing ground is associated with the ring conductor toring the bell at subscribers station B; This cir cuitmay betraced from the negative'ringing current sourcethrough the lower contactfof cam 302, normal contact ofrelay 320, windingof relay`322, upper contact of cani 306, `terminal 260i, brush '263, conductor 271, right upper contact or ycam 212, con-. ductor 117, brush l113 and its associated con tact, upper contacts of relay-102, conductor, 104, the bell magnets of subscribers stations vA and `B to ground. The bell magnets ofv stations C and D are at this time shunted by a circuit over the lowerk innermost contacts of relay 102, brush 112r and its associated` contact, rconductor 116,y left upper contact of cam 213, brush 264 terminal 259 to ,groundy through the lower `contact of cam304.l ,j f

The ringer magnet and *its associated armature of subscrbers station Bis adjust ed'to -operate from negative ringingcurrent 80 applied to the tip conductor vofthe line-and when properly `adjusted respond to the ringing currentimposed 'upon the line by the testing device, Fig. 3.

the repairman to remove the receiver froin Atheswitchhook to establish a low resistance circuit in thelsubscribers station.: f It will be noted that the ringing current 1s trans'- A mittedthrough the -winding relay 322 which` is adjusted in such manner that it will not operate during the period when the ringing current isv transmitted through the ringerwinding. However, when the receiver is revmoved from the switch'hoolr to establish a.- .low resistanceline loop, theicurrent then transmitted through the winding ot relay v322 is sufficient to cause its energization.

`3, from position 5 to position 8.y This cir-:

cuit may be tracedk from grounded battery through the winding of ymagnet`300, right contact of cam 311 to ground through they normal contacts oli-relay 321. The sequence switch is now rotated from position S to its normal position l. under the contr-ol of the master contact 331. y. The release of relay 228 establishes circuits to rotate the district selector sequence switch out of position 15; The district selectorthen restored to normal in the manner described in vPatent No.

1,395,977, previously referred to.

In a similar manner a repairman at station A, upon receiving thetone impressed upon the line conductors by tone interrupter 330, will dial 1, instead of 2, asdescribed for station B or if at station C or D will dial 3 and 4, respectively. The number oi` counting relays operated in Fig.j3 cor-k responds with the number or'k interruptions from the ydial Vat the subscribers station.

This circuitmay be used in conjunction with single partylines; and forsuch lines the usual practice lis to associate alternating current with the subscribers station to energizel the ringer magnet, since forsingle' party When the bell is sounded it is theduty of f' CLI lines it is not necessary to adjustthe ringer to operate from a particularly poled source of current.

rThe testing device, Fig. 3, may be used in conjunction with any ofthe various methods of ringing subscribers stations, by associating ringing current sources with the contacts .oi` cams 301 and 302 such as is required to operate the subscribers station to malte a service connection.

4Should the testman at a subscribers station dial the code to associate the testisetiin operative relation With the line, and, upon receiving the tone ronrtone vsource 330, de-

' cide that he does not desireto ring the bells,

the receiver may be restoreduponthe switch hook to cause the test setto restore to normal. It Will be remembered that the tone is transmitted in sequence switch position 3. The restoration of the receiver releases relay 325 which, in turn, releases relay 324. The release of relay 825 operatescounting relay l over an obvious circuit. The release of relay 324 establishes .a circuit to lenergize sequence switch magnet 300 to rotate the sequence switch from position 3 to 4. l/Vhen the sequence switch `rotates out of position 3,-a shunt is removed from the Winding of counting relay l to cause its operation. The operation ot counting relay l establishes a circuit to energize magnet 300 to restore the sequence switch to normal and release the counting relai This circuit may be traced from grounded batt-ery through the Windingof magnetBOO, right loiver contact of cam 811, vright contact oit counting relay 1', right normal contact of counting relay 2', contact of cam1309, to ground through the normal contact of relay 324.

What is claimed is:

l.. In a testing system tor testing subscribers station apparatus associated with single or party lines ot a central otlice, a testing device. located in said central oiiice, means for directing acall from a subscribersstation to `said testingdeviceand means for testing only the subscribers `station from which said call is initiated independent ot -manual assistance at said central ottice.

2. In a testing system for testing .subscribers station apparatus associated -With single or party lines of a central oiiice, a testing device located in said central otiice, means for directing a call `from a subscribers station to saidtesting device, a .source of .ringing current `and rautomatic ine-ans in saidA testing device responsive toj said call for associating said ringing current'source only with the subscribe1"s station from which said call' is initiated.

3. In a testing system for testingfsubscribcrs station apparatus associated ywith single or party. lines of a central oilice, a testr .ing .device -located -in said central oiiice,

.means for .directing a call trom a subapparatus of said subscribers station.

t. In a testing system for testing subscribers station apparatus associated With single or party .lines of a central office, a testing device located in said central oice, means for directing a call from a subscribers station to said testing device, sources ot ringing current ot ditierent characteristics, and means to control said testing device :trom a subscribers station to associate ringing current only with said subscribers station, said ringing current having the characteristics ordinarily used in service to actuate the apparatus of said subscribers station.

In `a testing system for testing subscribers station apparatus associated with lsingle or `party lines ot la central otlice, a testing device located in said central oiiice, sources ot ringing current of ditferent characteristics associated with said testing device, and means to control said testing deviceirom a `subscribers station to associate ringing current only With Asaidsubscribers station, said ringing current having the proper characteristics to actuate the apparatus oi' said subscribers station in accordance with its adjustment.

G In a testing system for testing subscribersstation apparatus associated with a central otiice, a testing device located in said 'central ottico, means under the control or" a subscribers station for associating said subscribers station with said testing device, sources of ringing current associated with said testing device, means under the control of said subscribers station to select one of said sources ot ringing current, means to connect said selected source of ringing current for actuating the apparatus ot' said subscribers station, and means under the control ot said subscribers station to disconnect said ringing source.

A7. ln a testing system for testing subscribers stations equipped with dials and associated with a central oiiice, a testing dcvice located in said central otiice, meansfor directinga call to said testing device by a particular manipulation ot a dial-at a subscribers station, means for associating a tone source with said subscribers station to indicate that a testing device has been selected, sources of ringing current, and means to control said testing device by further manipulation of said dial to associate ringing current with said .subscribers .station of a potential and polarity to actuate the aplli paratus of said subseribers station in acof a particular polarity to properly test" y cordance with its adjustment. said station, the ringing current of said par '10 8. Ainethod of testingvsubscribers station tcular polarity being selected in response apparatus consisting in transmitting a set to said second signals. e n

of signals from a stationy to a central ofice, In testimony whereof, I have signed my receiving an audible tone in response thereto, naine to this speoiioation this 26th day oi transmitting a second setof signals to said June, 1924.

central olioe andl receiving ringing current CARLETON V. TAPLIN.