US1888337A - Telephone system - Google Patents

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Publication number
US1888337A
US1888337A US536342A US53634231A US1888337A US 1888337 A US1888337 A US 1888337A US 536342 A US536342 A US 536342A US 53634231 A US53634231 A US 53634231A US 1888337 A US1888337 A US 1888337A
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Prior art keywords
relay
armature
circuit
conductor
trunk
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US536342A
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John H Voss
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Associated Electric Laboratories Inc
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Associated Electric Laboratories Inc
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Application filed by Associated Electric Laboratories Inc filed Critical Associated Electric Laboratories Inc
Priority to US536342A priority Critical patent/US1888337A/en
Priority to GB24311/31A priority patent/GB388752A/en
Priority to FR726873D priority patent/FR726873A/fr
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/58—Arrangements providing connection between main exchange and sub-exchange or satellite
    • H04Q3/62—Arrangements providing connection between main exchange and sub-exchange or satellite for connecting to private branch exchanges
    • H04Q3/625—Arrangements in the private branch exchange

Definitions

  • T0 was cm SIGNAL -Inuen 0 x"- Juhn H. Uuss Nov. 22, 1932.
  • This invention relates to telephone systems in general, but is concerned more particularly with small systems of 'the type commonly known as private automatic exchanges.
  • Private automatic exchanges are as a rule privately owned'by individuals or corporations' and are installed in factories or other establishments for providing local service between a small number of local telephone lines and for establishin lines to the main 0 cc of the telephone coma panys network.
  • a further object of the invention is toprovide holdin means whereby one trunk connection can e held while the local subscriber receives a local call, makes a local call, makes an outgoin trunk call, or; answers an'incoming trun call over the same telephone set.
  • the local subscriber may, if desired, hold both trunk calls and return to each as desired or may transfer one of the trunk to another local subscriber.
  • a still further object of the invention is to provide guarding means for held trunk lines and for enabling only a certain subscriber to connections over trunk calls 1931. Serial No. 538,842.
  • trunk line is to be transferred to such subscribers line.
  • One of the features of the invention resides in the circuit arrangements whereby it is not necessary for a subscriber in making an out-" going trunk call or in answering an incoming trunk call to know which trunk to connect with. That is, a subscriber always. operates the same'key in accepting atransferred or answering an incoming trunk call on any trunk line and always operates the same outgoing key to make outgoing trunk calls re-,
  • Fig. 1 illustrates two local subscribers lines S and S in which the line S can make and receive local calls only, while the line S can 'make and receive trunk calls, can transfer .trunk calls and can hold trunk calls while making or receiving local calls.
  • Fig. 2 illustrates a local subscribers lme S which can make and receive both local and trunk calls, can transfer trunk calls to other local lines, and can hold trunk calls while making, answering, or transfer-ring other trunk calls.
  • Fig. 3 illustrates the wipers and relay
  • Fig. 5 illustrates a code-call finder switch.
  • Fig. 6 at TSS illustrates the transfer sequence switch
  • BTR illustrates the busytone relays
  • RIB illustrates the ring-1n- PATENT OFFICE terrupter relays
  • ASR illustrates the alarm-signalling relays.
  • Figs. 7 and 8 illustrate the wipers of the trunk finder and relays of a two-way trunk circuit which is one of a number of trunk circuits connecting the local automatic exchange to a telephone exchange of the telephone eompany s network.
  • each set comprises a handset T and R, a calling device CD, a cradle and cradle spring CS, an induction coil IC, and the ringer bells RB.
  • Each line has a local line circuit, the conductors of which'terminate in the local finder andconnector banks for completing local calls.
  • Each local line circuit has a two-step cut-oil relay and a line relay, such as relays 7. 117, and 217, which is common to a groun of lines.
  • each standard mono.- phone set of subscribers lines such as S and and S
  • a sub-base such as SB shown in the dotted rectangle. having a number of spring assemblies and keys for operating the same when making or receiving trunk calls.
  • the sub-base of the subscribers lines, such as S have only two keys, an OUT key for initiating outgoing trunk calls, and an ANS key for answering incoming trunk calls; while the sub-base of subscribers lines, such as S, have an additional or HOLD key.
  • a push-button is also provided in the sub-base for flashing an operator in a trunk call to a manual exchange or for cancelling the digits dialled if an error has been-made in dialling an automatic subscriber in either the local or a distant automatic exchange.
  • Conductors extending from the spring assemblies controlled by these keys extend to the trunk-line circuits and from there ter-' minate in the banks of the trunk finder.
  • trunk-line circuits of subscribers lines such dition. have/an individual holding circuit comprising four relays, one'of'which is also a two-step cut-ofi relay.
  • Thev trunk-line circuits of S 'subscribers terminate in the banks of a trunk finder in the same manner as the S.
  • subscribers trunk-hne c1rcu1ts,'and, in addi-- tion, terminate in an additional set of bank contacts in the trunk finder fo'renabling the subscribers lines, such as S to hold one trunk connection while talking over another.
  • the local line circuitsof the S subscribers" lines also terminate in two places in the local finder banks for enabling such subscribers to transfer a second trunk call to another 251, 252.256, 257. and 258.
  • the HOLD key controls only springs 259.
  • the three keys ANS, OUT, and HOLD are keys or levers which aremoved oil center and remain in such positions until moved by hand back to normal or until the handset is replaced on the cradle which automatically returns the keys totheir normal positions.
  • the push-buttonPB', controlling springs 250 is of the self-restoring type and operates the springs '250 only as long as the1push-button is depressed.
  • the finder switches are mechanically similar to the Ill) well-known rotary lineswitch having no normal position. while the circuits thereof have been altered inaccordance with the present invent-ion.
  • The-start relays SR shown at the bottom of Fig. 3, are arranged to start alternate finders included in Jthe group of finder-connector links in the "manner to be more 'fully described hereinafter.
  • the connector switch. shown in Fig. 4 is mechanically similar to the finder, but instead of automatically hunting for a marked potential as the finder does, the connector is directly controlled, in part, by impulses to a certain set of contacts and is thereafter automatically rotated to normal position after termination of a call.
  • the chain start circuit through the remaining finder connector links is diagrammaticzilly illustrated in the dotted rectangle.
  • dial-tone relay 453 for generating dial tone is common to all of the finder connector links.
  • the dotted rectangle illustrates the connections for enabling local subscribers to make conference calls. The resistance shown'in the dotted rectangle is connected to only one of the switch banks and is not multipled, while the conductors 462 and 47 2 extending to relay 468 are common and are multipled between the banks of the various connector switches.
  • the code-call finder switch shown in Fig. 5 is mechanically similar to the finder of the finder connector link and also hunts for a marked potential.
  • the rela s associated with this switch are for enab ing a calling subscriber to send out ringing current impulses over the code-call circuit in accordance with dialling impulses.
  • the code-call switch is accessible from the banks of the connector switch.
  • the transfer sequence switch TSS shown in Fig. 6 is mechanically similar to the aforementloned rota lineswitch, being, however, of a small capacity and permits onl one call at a time to be transferred.
  • the usy-tone relays, BTR comprise relays when operated for generating abusy tone,'while the ringing interrupter relays, RIR, comprise relays for generating interrupted ringing current.
  • Relay.621 is equipped with a vibrating armature 626 which vibrates between its upper and lower contacts when the relay 621 is deenergized.
  • the alarm signalling relays ASR are provided for transmitting alarm signals over a two-conductor trunk to the main telephone exchange when trouble occurs.
  • Figs. 7 andS one of a number of twoway trunk circuits is shown connecting the local prlvate automatic exchan e with one of the telephone companys exc anges which may be either manual or automatic.
  • the trunk circuits terminate in the private automatlc exchange in trunk relay groups and finder switches for connecting theftrunk's to the local subscribers lines.
  • the trunk finders are mechanically similar to the local.
  • relay 768 shown in the dotted rectangle, is provided for sequentially taking the trunk finders into use.
  • the dotted rectangle shown to the lower right of Fig. 8 diagrammatically illustrates a portion of the chain circuit extending through the trunk circuits.
  • the correspondingly numbered armatures illustrate similar armatures on the succeeding trunk circuits.
  • Relay 833 shown near the upper portion of Fig. 8, is the incoming signalling relay is common to all of the trunk circuits, and
  • the core of these switching relays are provided with tted strap L two windings wh ch are separated by a magneticspacin member, a projection of which extends bac and forms a back stop against which the armature of the'relay rests.
  • the winding on the heel end of the relay is the magnetlzing soil, and the flux produced thereby traversing the path including this magnetic iron back stop, which is in shunt of the air gap, and no amount of flux strength in this magnetizing coil will cause the armature to operate.
  • subscriber S desires'to call subscriber S.
  • subscriber S will remove the handset from the cradle and dial digits 4 and 2 correspondrelay 7, armature 4, conductor 1, impulse "sfrrings of the calling device CD, transmitter u. per ring of the cradle springs CS, mid e win ing of the induction coil IC, con-- ductor 2, armature 6, and through the upper; winding of relay 3to battery.
  • Relay 3 en ergizes and at. this time operates only its armature 5 to mark the line S as calling in the banks of the finder over conductor 11.
  • Relay 391 locks to armature 398 and at armature 396 preparesthe circuits to relay 392, when ground is removed from conductor 9, relay 390 releases, while relay 391 is maintained energized in series with relay 392, which now energizes since the short circuit has'been removed.
  • Relay 392 at armature 397 switches the start circuit from conductor 377 to conductor .378.
  • relay 390 grounds the start conductor 378 instead of conductor 377.
  • Armature 395 closes a short circuit around relay 391 which tie-- energizes, while relay 392 is maintained operated.
  • relays 390 and 392 deenergize with the result that all of the relays are now in the normal position. The alternate grounding of conductors 377 and 378 causes successive finder connector links to be taken into use in response to successive calls.
  • ⁇ Vhen conductor 377 is grounded, a circuit may be traced for energizing start relay 310 ofthe finder as follows: from grounded conductor 37 7 armature and its resting contact, armature 331 and its resting contact, and
  • start relay 310 completes an energizing circuit for stepping relay 308 by way of armature 318 and its resting contact and interrupter springs 316 of the'niotor magnet 307.
  • Motor magnet 307 positions its pawl preparatory to stepping the wipers ofthe finder and at armature 316 opens the circuit of stepping relay 308.
  • motor magnet .307 upon-dcenergizing, reestablishes the circuit for stepping relay .308 with the result that the stepping relay energizes and again completes the circuit for energizing the motor magnet 307. This interaction between the stepping magnet 307 and the stepping relay 308 continues until test wiper 303 encounters a calling potential, in this case a negative battery potential.
  • a circuit may be traced for energizing relay 309 in series with relay 3 as follows: from ground by way of armature 319, upper operating winding of test relay 309,'test wiper 303 in engagement with the fourth bank contact, conductor 11, armature 5, and through the lower winding of relay 3 to battery.
  • Relay 3 is energized through its second step, thereby operating armature's 4 and 6 to disconnect the common line relay 7 and to disconnect the upper winding of relay 3 from line conductor 2.
  • Common line relay 7 deencrgizes and at armature 8 removes ground from the common start conductor 9 with the result that the start relays SR in Fig. 3 operate in the same manner as previously described.
  • test relay 309 upon energizing, at armature 318 closes a circuit for energizing relay 312 over an obvious circuit and also opens the circuit extending to the stepping relay 398 and stepping magnet 307
  • the finder therefore, comes to rest in engagement with the wipers 301 to 306, inclusive, in en agewent with their fourth bank contacts.
  • clay 312 upon energizing, at armature 32 9 opens a point in the circuit of alarm relay 650; at armature 331 opens a point in the circuit of start relay 310 at its resting contact, and at its working contact closes a. point in the chain circuibto the next finder connector link.
  • $tart relay 310 does not immediately deenergize on account of the co per slug, diagrammatically illustrated by t 1e upper black portion, which renders the same slow-to release as well as slow-to-energize.
  • relay 312 grounds test wiper 303, thereby grounding conductor 11 and making the line S busy; and at armature 328 prepares a locking circuit'for relay 311.
  • At armatur'cs 334 and 332 relay 312 close'sthe circuit for the line relay 407 for the connector as follows from ground through the lower winding of line relay 407, conductor 375, armature 332, armature 326, wiper 306 in engagement with the fourth bank contact, line conductor '2' over the callin' loop of subscriber S to line conductor 1, o armature 333, armature 334, conductor 363 to the upper'windingof line relay 407 to battery.
  • Line relay407 upon energizing, at.
  • armature 416 completes a circuit for energizing slow-to-release relay 4-08 over an obvious circuit;
  • Relay 408 at armature 421 grounds conductor 367 before relay 310 fully deenergizes in order to hold relay312 in operated position.
  • release relay 408 prepares a circuit for switching relay 414;
  • Relay 413 at armature 437 prepares a circuit for the series relay 409; at armature 438 prepares a circuit for relay 410; at armature 439 places another ground connection on .conductor- 367, at armature 449 removes ground from the multipled bank contacts and conductor 466, at armature 440 completes a circuit for energizing the differentiallywound dial-tonerelay 453 which now operates in the manner of a buzzer to generate dial tone, and at armature 441 closes a circuit for connecting dial tone to the calling subscribers line.
  • the dial-tone circuit may be traced as follows: from. armature 454 of the dial-tone relay 453, conductor 456, normal-position bank contact and wiper 406, armature 441', resting contact of armature 436 and said armature, armature 429, through the two condensers in series, conductor 375 from whence the dial tone may be traced over the loop circuit previously traced.
  • subscriber S will then operate the calling device CD in accordance with the number of the desired subscriber, in. this case subscriber S or number 42.
  • the operation of the calling device for the first digit interrupts the line circuit of line relay 407 four times, thereby causing line relay 407 to deenergize four times.
  • Release relay 408 as illustrated in the drawings has a copper sleeve around its core, thereby making the same slow-to-release, and inthis case, release relay 408 does not deenergize during the dialling period.
  • circuit may be traced for energizing stepping magnet 415 as follows from ground by way of the normally closed springs controlled by armature 416, armature 420, armature 434, armature 446, and through the Windingof motor magnet- 415 to magnet.
  • Motor magnet 415 energizes and operates its pawl preparator to stepping the wipers'of the connector. branch of this circuit extends from armature 446, by way .of armatures 437 and 417 for energizing'slow-to-release series relay 409.
  • series relay 409' closes a' shunt circuit around armature spring 434 controlled by busy relay 412; at armature 422 prepares a point in the circuit for busy relay. and at armature 424 and its workingc a I 1 contacts closes a CII'Cllli ⁇ for energizing relay 410 as follows: from ground by way of armature 424, armature 348, wiper 404 in normal po it on, conductor 369, armature 322 which by this time has closed, conductor 368, normally closed spring controlled by armature 428 through the resistance and upper win ing of relay 410 to battery. Relay 410 at a mature 425 opens a point in the test circuit;
  • armature 426 prepares a point in the circuit for relay 314, at armature 427 prepares a point in the automatic stepping circuit for the connector switch in case the digit; 4 is dialled; at armature 428 completes a locking circuit for itself from closed armature 424;
  • series relay 409 will take four steps and come to rest 'deenergization of series relay 409 is the establishment of an automatic steppingwircuit for magnet 415 as follows: from ground by way of contacts 467,'wiper 404, armature 438, armature 424 and its resting contact, armature 427, armature 447, interrupter springs 448 and through the winding of magnet 415 to battery.
  • the motor magnet 415 operates in a buzzerlike manner until wiper 404 no longer encounters a grounded contact, the first ungrounded contact being the fourteenth contact accessible to wiper 404.
  • Relay 410 also deenergizes when wiper 404 reaches its fourteenth contact.
  • the wipers 401 to 406, inclusive will come to rest on their third set of contacts. Wiper 404 does not, therefore, encounter ground with the result that relay 410 deenergizes when its circuit is opened by relay 409. The wipers are not automatically 'impulses are sent out over the calling loop to operate line relay 407 as before.
  • the series relay 409 and motor magnet 415 operate in the same manner as described, but relay 410 does not energize because its original energizing circuit was opened when wiper 404 moved off normal.
  • the wipers 401 to 405, inclusive are operated into engagement with their sixteenth bank contacts terminating the conductors associated with theline of subscriber S.
  • relay 409 deenergizcs and at the make-before-break .5 rings of armature 422 completes a locking circuit for the busy relay 412 as follows: from ground by way of armature 418, armature 433 and, its working-contact, normally closed springs controlled by armature 422 and t rough the winding of busy relay 412 to battery. 7 I
  • Atarmature 435 busy relay grounds the busy and generator-start conductor 371, thereby energizing relay 615 over the common conductor 360.
  • Relayr615 at armature 626 starts the ringing'vibrator by energizing the difl'erential relay 640 through its lefthand winding which operates the vibratory 641 to the left to close'a circuit through the right-hand winding in opposition to the left hand winding.
  • Relay 640 being diiferentially wound, releases its vibrator 641, thereby causing the vibrator to swing to the right and open a circuit extending through the right-hand winding.
  • the vibrator 641, therefore, vibrates and closes alternate circuits through windings 642 and 6430f the induction coil to set up current flow in op poslte directions.
  • relay 615 closes a circuit for energizing relay 620 over armature 637 and its-resting contact.
  • Relay 620 at armature 6 closes a circuit for energizing relay 621 by way of armature 639.
  • Relay, 621 attracts the vibrating armature 636 to close its lower contact-and thereby close a circuit for energizing slow-acting relay 622 by way of armature 634.
  • relay 622 energizes, and at armature 637 opens the circuit of slow-tiY-releasc relay 620 and at armature638 closes a circuit for energizing slow-to-release relay 623.
  • Relay 623 at armature 639 opens the circuit of relay 621 which deenergizes and releases lt S vibratlng armature 636. Armature 636 vibrates between its upper and lower contacts to hold rela 622 energized for a .pre-
  • Relay 615 upon energizing, at armature 625 completes a circuit for energizing relay 616 and busy interrupter relay 618.
  • Relay 618 is difierentially wound and operates like a buzzer to open and close springs 630.
  • lay 616 at armature 627 opens the short circuit from around relay 617, thereby causing the energizatlon of the latter relay.
  • Relay 617 at armature 629 closes the busy-tone generated by relay 618 to the common busy-tone conductor 459.
  • relay 617 closes a short circuit around relay 616 which deenergizes after an interval and reestablishes the short circuit around relay 617 which also deenergizes after an interval.
  • lVhen relay 617 deenergizes, the tone is dis connected from conductor 459 at armature 629, and at armature 629 the short circuit around relay 616 is removed and relay 616 reenergizes to again Ereenergize relay 617. This cycle of operations continues as long as ground is connected to conductor 360.
  • busy-tone may be traced from conductor 459 over the working contact of armature 436 and said armature, armature 429 and over the calling loop.
  • the calling subscriber will replace the handset on the cradle and the'finder connector link in Fi 3 and 4'will be released in a manner to subsequently described.
  • Witching relay 414 operates its'armature 445 to complete a circuit from grounded armature 419 cut-01f relay .
  • armature 450 grounds conductor in order to fully operate the relay and to ductor 102, through the substation circuit to complete a locking circuit for' itself.
  • push-button springs 150, con armature 443, relay 414 grounds the test ductor 121, spring 156 and its resting contact,
  • wiper 403 to busy the calledline and to mainconductor 131, wiper 401, armature 442,
  • relay energizing at armature 429 disconnects ring- 414 opens the point in the impulsing circuit; back tone; at armatures 428 and 427 preat armature 447 opens a point in the autopares circuits for maintaining relay 410 in matic restoring "circuit of the connector, at operated position during the automatic re- 1 to start storation of the connector to normal; and the busy and ringing interrupter relay as preat armature 426 completes a circuit or enviously described; at armature 451 closes a ergizing relay 314 as followszfrom ground by ring-back circuit to the calling Subscriber way of armature 419, armature-444 and its 7 by way of conductor 457, resting contact of working contact, armature 426, conductor armature 432 and said armature, armature 366 and through the winding of relay 314 451.
  • armature 436 restingcontact of armature 436 and said to battery.
  • relay 314 comarmature, armature 429 and thence over the pletes a locking circuit for itself over concalling loop; and at armatures 442 and 452 ductor 365 independent of relay 410; at connects ringing current to the called-line.
  • armature 342 connects the upper winding of Relay 413, upon deenergizing, at armatures relay 313 in series with-wipers 302 and 402 439' and 449 prepares circuit for automatifor a.
  • relay 113 When cut-01f relay 113 energizes in series at armature 416 opens the circuit of release with switching relay 414, relay 113 operates relay 408 which deenerglzes after a short 1nall its armatures to disconnect the common terval.
  • relay 408 removes line relay 117 at armature 114; at armature holding ground from relays 411, 414, and 314 116 disconnects the upper winding of relay which now deenergize; at armature 421 re- 113 from conductor 132 and at armature 115 moves ground from conductor 367', thereby connects conductor 110 to conductor 111 to deenergizing'hold relay 312, and at the restbusy the line in the banks of the local finder ing contact of armature 421, closes a c1rcu1t and code-call finderfor automatically restoring the connector When subscriber S removes the handset wipers to normal position.
  • This circuit may from the cradle in ,response to the operation be traced as follows: from ground at armaof the ringer, bells RB, ring cut-01f relay 411 ture 449, or from ground at the multiply is energized over the calledsubscribers loop connected contacts 467, wiper 404, normally and said relay at armature 431 completes a closed springs controlledby armature 439, locking circuit for itself.
  • armatures 430 armature 421 and its resting contact.
  • armaand 432, relay 411 disconnects the ringing ture 447, interrupter springs 448 and through is current from the line conductors and eo'ithe winding of motor magnet 415 to battery.
  • a circuit may a buzzer to step the wipers 401 to 406, inclunow be traced for the back-bridge or batsive, until thewiper 404 loses ground which tery-feed relay 410 as follows: from ground it does when it reaches its normal position or through the lower winding of relay 410. the position shown'engagedby the wiper working contact of armature 432 and said in the drawings.
  • tures 331 and 331, in the various finder-com nector links would be operated with the result that no circuit iscompleted to a start relay, suchas relay 310 and, therefore, no finder connector link would be seized and the calling subscriber would not receive dial tone, thereby indicating such a busy condition.
  • Relay 806 is a very high wound relay and opcrates in response to either the ringing current or during the silent eriod, while relaylay807 at armature 827 completes a locking circuit.
  • Relay 808 operates in response to ringing current and at armature 831 closes a circuit for signalling relay 833 whichrelay, at armature'834, completes a circuit for operating the incoming trunk signals over conductor 835.
  • Relay 804 upon energizing, at armature 820 completes a circuit for energizing at relay 803; at armature 819 completes the locking cir cuit for ring-u 'relay 807; at armatures 821 and 822 comp etc points in the chain circuits; and at armature 818 completes a circuit for energizing slow-to-operate relay 650 which relay, however, does not have time to energize'be fore its circuit is opened at armature 816 by relay 803.
  • relay 803 disconnects relay 802 from talking conductor 754 and connects the trunk conductor 840 in place thereof; atarmature 816, relay 803 prepares a locking-circuit for itself and at armature 817 prepares a locking circuit for car It will be assumed that subscriber S answers the incoming trunk call. To do this, subscriber S operates the ANS key and removes the handset from the cradle. In response to the operation of the answer key, springs 151, 152, 155, and 156 are operated in the manner previously described, and a circuit may, therefore, be traced from ground through springs 155, normally closed springs controlled by armature 143 and throughthe winding of'relay 141 to battery.
  • Relay 141 at armature 147 prepares a locking circuit for itself; at armature 146 and its working contact completes a circuit for the common incoming line relay 161; and at armature 148 disconnects the outgoing test conductor 167 and connects up the incoming test conductor 166.
  • A. circuit may now be traced for relays 161 and 140 as follows:
  • Cutoil relay 140 operates in its first step only to close armature 144 to connect a negative battery potential from the lower winding of relay 140 to conductor 166 which terminates in the test bank contact accessibleto test wiper 703 of the trunk finder.
  • Common line relay161 at armature 163, grounds the com-' mon incoming start conductor 165 to complete acircuit by way of conductor. 765, ar-
  • Start relay 711 at armaturel 726 completes an energizing circuitthrough the upper winding of relay 709 which energizes-and locks up through its lowerwinding; at armature 727 prepares the operating circuit for three-pole test relay 712, and at armature 728 completes a circuit for the lower electro-polarizing winding of relay 712 which relay, as previously described, will not operate until a circuit is completed through its operating winding in the proper direction.
  • relay ,711 completes a circuit for energizing stepping relay 708 as follows: from ground by way of armature 729. armature 730 and its resting contact, winding of relay 708 and through the interrupter springs 717 of the motor magnet 709 to battery. Stepping relay 708 at armature 718 completes a circuit for energizing the motor magnet 707 and the motor magnet, upon energizing, at its 7 interrupter springs 717 interrupts the circuit of the stepping relay 708 which now deenergizes. When stepping relay 708 is fully deenergiz'ed, said relay at armature 718 opens the circuit of the motor magnet 707 with the result that motor magnet 707 steps the switch wipers 701 to 706, inclusive,
  • Twostep relay 140 energizes through its second step .over this circuit to disconnect thelcom mon-line relay 161 at armature 142; to comill plete the locking circuit for relay 141 and to disconnect the upperwinding of'relay 140 from talking conductor 172.
  • Common line relay 161 deenergizes and at armature 163 removes ground from the incoming start conductor 165.
  • the threepole test relay 712- energizes over the abovet-ra'ced circuit and at armature 730 and its resting contact opens the stepping circuit, and at its working contact completes a circuit for energizing relay 713 from grounded armature 729.
  • relay 713 grounds the test wiper 703 to busy line S to other trunk finders; at armature 733 pre pares a locking circuit for itself; at armature 735 opens a point in the circuit of the slow-to-operate start relay which maintains its armatures attracted for ashort time thereafter and prepares a point in the chain cir cuit to the succeeding trunk finder; and at armatures 731 and 736 completesthe'talking circuit between subscriber S and the main exchange as well as completing a circuit for energizing relay 801.
  • the circuit for energizing relay 801 may be traced as follows: from ground applied to' conductor 840 at the main exchange, armature 814 and its working contact, conductor 754, armature 731, wiper 701, conductor 171, through the sub-station circuit and sub-base keys over the circuit previously traced to conductor 172, wiper 706, armature 736, conductor 766, winding of relay 801, resting contact and armature 813 and said armature, and over trunk conductor 841 to battery.
  • relay 801 completes an energizing circuit for slow-to-release relay 805.
  • relay 805 opens the circuit of relay deenergizes a short interval after relay 806 7 deenergizes and at armature 819 opens the locking circuit of ring-up relay 807; at armature 820 opens the original energizing circuit 6f relay 803 which is now locked up over armature 823.
  • relay 716 in Fig. 7 energizes, said relay at armature 747 opens the, locking circuit of relay 807 whereupon the latter relay deenergizes and opens-the c rcuit of relay 808. It should be mentioned at this time, however, that in response to the operation of the switching-through relay 713 in Fig.
  • a bridge including the subscribers loop was placed across the trunk conductors 840 and 841 to automatically cut-0H the ringing current.
  • Relay 808, upon deenergizing, at armature 831 opens the circuit of the com mon signalling rela-y833 with the result that the incoming signals are no longer operated in response to this trunk call.
  • relay 716 prepares a, circuit for relay 715 which will be effective only incase the trunk call should be transferred to another local subscriber as will be more fully described hereinafter.
  • relay 716 completes a locking circuit for itself over conduct-or 758 and armature 817; at arma ture 750 completes a.
  • Relay 801 upon deenergi'zing at armature 810 opens the 'circuit of relay 805 which deenergizes and at armature 823 opens the locking circuit of relay 803 and at armature 825 opens a point in the original energizing circuit of relay 716.
  • relay 803 deenergizes and at armature 814 disconnects the incoming trunk conductor 840 from the talking conductor 754; atarmature 816 opens a point in its own locking circuit; and at armature 817 opens the locking circuit of relay 716.
  • relay 716 upon .deenergizing, opens the locking circuit of Outgoing calls It will now be assumed that subscribers desires to call a subscriber in the main automaticor main manual exchange over one of the trunk circuits, such as shown in Figs. 7 and 8. Subscriber S thereupon operates the OUT keycin the sub-base SB, thereby operating the bar 261 in av horizontal direction to operate springs 251, 252, 256, and 258; In
  • a circuit may now be traced from ground through the common outgoing line relay 260, terminal 203 connected to conductor 204, resting contact of armature 246 and said armature, armature 242, resting contact of armature 291 and said armature, working contact and springs 251 and said, spring, conductor 202 through the calling subscribers loop a to conductor 201, push-button springs 250, conductor 221, spring 256 and spring 258, armature293 and its resting contact, armature 297 and its resting contact, and through the upper winding of two-step relay 240 to battery.
  • Two-step relay 240 energizes and operates only armature 244 in its first step at this time to connect the calling potential extending from the lower winding of two-step relay 2-10 to the outgoing test bank contacts accessible to wipers 702 of the trunk finders such as shown in Fig. 7.
  • the common outgoing line relay energizes over the above-traced circuit and at armature 262 grounds the. common outgoing start conduc tor 164 to complete a circuit for the start relay ofthe first idle trunk finder.
  • the start circuit will extend by way of armature 722 and its resting contact, conductor 764, armature 822 and its resting contact, conductor 763, arma ture 745 and its resting contact, armature 735 and its working contact, conductor 762 to the succeeding trunk finder, armature 722 and its working contact, and conductor 7 62 to the next succeedingor third trunk finder.
  • the chain circuit is taken through armature 822 and its working contact to the succeeding trunk finder.
  • the start circuit is completed by way of armature 745 and its working contact instead of its resting contact.
  • the start circuit extends through the chain circuit of all of the trunk finders in the manner previously described to conductor 671, thereby completing a circuit for relay 619 to initiate the operationof the busytone relays 616, 617, and 618 as previously described.
  • all-trunks-busy relay 619 closes the busy-tone circuit as fol.- lows: from vibrating armature 630, interrupter armature 629, armature 632, the condenser and conductor 106, through Fig. 5 to Fig.2, conductor 206, and through the wind ing of common outgoing line relay 260 and over the calling subscribers loop circuit.
  • the calling sul scriber may either replace his receivcr or waituntil an idle trunk circuit is available. It is believed advisable at this time to describe another branch of the chain circuit which has been provided to insure the successive seizure of trunk circuits when making outgoing calls.
  • Conductor 760 of the first trunk finder extends to terminal such as terminal 7 53 in the succeeding trunk finder and so forth through the chain.
  • the relay 7 09 is energized and locked, and when the last trunk finder is taken into use in an outgoing call, a circuit may be traced from armature 721 of the last trunk finder for energizing slow-to-operate relay 7 68 over conductor 767.
  • Relay 768 at armature 769 opens the locking circuit of all relays 7 09 in the various trunk finders to cause their release so that the sequence of seizing the trunk circuits on succeeding calls will start all over. again.
  • the relay 709 in the last trunk c rcuit is deenergized, the relay 7 68 will also be energized afterian interval and again prepare the locking circuits for the relays, such as relay 7 09, in the trunk circuits. It will now be assumed that the trunk finder shown in Fig. 7 is the first idle trunk finder, and, therefore.
  • start relay 711 when the common outgoing start conductor is grounded, a circuit may be traced for the start relay 711 over armature 722 and its resting contact, conductor'764, armature S22 and its resting contact, conductor 763, armature 745 and its resting contact, armature 735 and its resting contact, and through the winding of start relay 711 to battery.
  • Start relay 711 at armature 726 completes a circuit for energization relay 7 09 which now locks up over its armature 720. and at armaturcs 727, 728. and 729 prepares the test circuit through the three-pole test relay 712 and completes the stepping circuit for the stepping relay 708 and motor magnet 707 in the same manner as described for an incoming call.
  • the wipers 701 to 706, inclusive, of the trunk finder are operated step-by-step in the manner previously described until the outgoing test wiper 702 encounters the negative battery calling potential applied to conductor 267.
  • a circuit may be traced for energizing the three-pole switching relay 712 in series with the two-step relay 240 as follows: from ground at armature 727 through the upper operating winding of relay 712, armature 742 and its resting contact, armature 723 and its resting contact, wiper 702, conductor 267, resting contact of armature 248 and said armature, armature 244 and through the lower winding of relay240 to battery.
  • Two-step relay 240 energizes and operates its armatures through their second step to disconnect the common line relay 260 at armature 242, and to disconnect the upper winding of relay 240 from the lower talking conductor 272.
  • the three pole test relay 712 is energized over the abovetraeed circuit, andat armature 730 opens the stepping circuit at its resting contact, and at its working contact completes a circuit for energizing. switch-through relay 713.
  • armature 732, relay 713 short circuits'the upper operating winding of relay 712 and also connects ground to test wiper 702 to make the'line S busy.
  • armatures 731 and 736 connects the calling subscribers loop circuit to conductors 754 and 766 over the following circuit: conductor 754, armature 731, wifper 701, conductor 271, restingcontact o armature 291 and said armature,
  • the operation of the trunk finder is slightly difi'erent dependent upon whether the trunk conductors 840 and 841 extend to a manual or an automatic exchange. In either case, ground is disconnected from the trunk conductor 840 at the main exchange, while the conductor 841 extends to a signalling relay and negative battery in case of a manual exchange, or extends through the line'relay to battery of an incoming lineswitch in case the main exchange is an automatic exchange.
  • relay 802 in Fig. 8 is permanently short circuited in case the trunk conductors 840 and 841 extend to an automatic exchange, while the short circuit is removed from around said relay'in case the trunk conductors extend to a manual exchange.
  • Relay 801 at armature 810 completes a circuit for energizing relay 805 and relay 802 at armature 811 also completes a circuit for energizing relay 805, and at armature 812 connects negative bat- 35 terv to the lower terminal of relay 801 to maintain this relay energized, and at armature 813 connects ground to conductor 841 to maintain the incoming signal relay, operclosing a circuit extending by way of the normally closed springs controlled by armature 816, armature 823, and through the winding of relay 803 to battery for energizing the latter relay.
  • Relay 803 at armature 816 completes a locking circuit for itself and also completes, at armature 817, the locking circuit for relay .716.
  • relay 803 opens the circuit of relay 802- and prepares a point in the talking circuit between the subscriber S and the manual operator. A short period thereafter, relay 802 deenerizes, and at armature 813 completes the talkmg circuit over the heavy talking conductors.
  • the calling subscriber S informs the manual operator of the-subscriber desired,- and the manual operator completes the connection in the well-known manner.
  • the line relay of the incoming lineswiteh in the automatic exchange operates in the well-known manner to seize an idle trunk at which time dial tone is transmitted back over conductors 840 and 841 to the calling subscriber.
  • ground is connected to trunk conductor 840, thereby causing the energization of relay 803 which now energizes and causes the cnergization of relay 716 over circuits previously traced.
  • relay 802 Since relay 802 is not operated on calls to automatic exchanges, a direct metallic loop circuit is completed over conductor 8-10, armature 814 and its working contact, conductor st over the previouslytraced subscribers loop circuit to conductor 766, through the winding of relay 801, resting contact of armature 813 and said armature, and over the trunk conductor 8-11 to the main exchange
  • subscriber S dials the telephone number of the desired automatic subscriber, whereupon the switches in the automatic eX- change are operated in the well-known manner to complete the desired connection.
  • Relay 801 intermittently operates, but since relay 805 is slow-to-release on account of the copper sleeve around its core, said relay is maintained energized throughout the impulsing period.
  • Subscriber S may originate an outgoing call in the same manner as described for subscriber S and subscriber S may answer an incoming trunk call in the manner similar to that described for subscriber S, and since the equipment and operation are somewhat similar, it is believed that a detailed description of such operations may be clearly understood without describing the same in detail.
  • H old'hzg trawl circuits In order to describe how subscribers equipped with sub-bases, such as SB, can hold a trunk call while either making or answering a local call, it will first be assumed that sub scriber S has answered an incoming trunk call and that the substation circuit of S is,
  • subscriber S informs the main-exchange subscriber to wait for a short period of time and then releases the answer key, whereupon the bar 161 is operated to the position shown in the drawings, thereby releasing springs 151 and 156,
  • T wo-step relay 113 operates only in its first step to operate armature 115 to connect negative battery calling potential over conductor 111 to the banks of the local finders.
  • Linc relay 117 upon energizing over the abovetraced circuit at armature 118 grounds the

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  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Sub-Exchange Stations And Push- Button Telephones (AREA)
US536342A 1931-05-11 1931-05-11 Telephone system Expired - Lifetime US1888337A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US536342A US1888337A (en) 1931-05-11 1931-05-11 Telephone system
GB24311/31A GB388752A (en) 1931-05-11 1931-08-28 Improvements in or relating to telephone systems
FR726873D FR726873A (fr) 1931-05-11 1931-11-24 Perfectionnements aux systèmes téléphoniques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US536342A US1888337A (en) 1931-05-11 1931-05-11 Telephone system

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US1888337A true US1888337A (en) 1932-11-22

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US536342A Expired - Lifetime US1888337A (en) 1931-05-11 1931-05-11 Telephone system

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FR (1) FR726873A (fr)
GB (1) GB388752A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2534850A (en) * 1945-04-04 1950-12-19 Bell Telephone Labor Inc Telephone system having preset transmitter
US2619550A (en) * 1947-11-26 1952-11-25 Siemens Brothers & Co Ltd Telephone extension control system
US2735892A (en) * 1956-02-21 Party line
US2824909A (en) * 1952-09-13 1958-02-25 Gen Telephone Lab Inc Telephone system
US2831065A (en) * 1956-03-29 1958-04-15 Gen Dynamics Corp Conference circuit
US3041406A (en) * 1959-12-14 1962-06-26 Gen Dynamics Corp Inward dialing to private branch exchange

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2735892A (en) * 1956-02-21 Party line
US2534850A (en) * 1945-04-04 1950-12-19 Bell Telephone Labor Inc Telephone system having preset transmitter
US2619550A (en) * 1947-11-26 1952-11-25 Siemens Brothers & Co Ltd Telephone extension control system
US2824909A (en) * 1952-09-13 1958-02-25 Gen Telephone Lab Inc Telephone system
US2831065A (en) * 1956-03-29 1958-04-15 Gen Dynamics Corp Conference circuit
US3041406A (en) * 1959-12-14 1962-06-26 Gen Dynamics Corp Inward dialing to private branch exchange

Also Published As

Publication number Publication date
FR726873A (fr) 1932-06-04
GB388752A (en) 1933-02-28

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