US2422285A - Selector operating circuit for use in automatic telephone systems - Google Patents

Selector operating circuit for use in automatic telephone systems Download PDF

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Publication number
US2422285A
US2422285A US478243A US47824343A US2422285A US 2422285 A US2422285 A US 2422285A US 478243 A US478243 A US 478243A US 47824343 A US47824343 A US 47824343A US 2422285 A US2422285 A US 2422285A
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Prior art keywords
relay
switch
selector
contacts
circuit
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US478243A
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Baker George Thomas
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Automatic Electric Laboratories Inc
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Automatic Electric Laboratories Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q1/00—Details of selecting apparatus or arrangements
    • H04Q1/18—Electrical details
    • H04Q1/30—Signalling arrangements; Manipulation of signalling currents
    • H04Q1/50—Conversion between different kinds of signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements

Definitions

  • the objects of the invention are concerned principally with the simplification of individual switch circuits, the elimination of relays on the individual switches and the rendering of the switch circuits so that they can be adapted for use with different kinds of selectors such as group selectors, final selectors or P. B. X final selectors in a ready manner.
  • the invention is directed to providing a novel exchange layout to permit of switch mechanisms fleeing interchangeable, to a novel control relay set and to novel selector switch circuits.
  • the invention is also directed to the reduction of the number of relay contacts in the switch train.
  • control relay set means a group of relays which precede a train of switches and exert controls over a plurality of circuits to brin about successive operations in the switches taken into use whereby the number of controlling relays individual to the switches may be reduced.
  • a telephone system includes a control relay set comprising an impulse-responding relay, a hold relay and a changeover relay, each of which exerts a separate forward control, a selector having an individual control circuit such that on co-operation with the forward controls exerted by the control relay set the selector functions as a group selector and a selector having an individual control circuit such that on co-operation with the forward controls exerted by the control relay set the selector functions as a final selector.
  • a control relay set is provided for successively bringing about the various steps involved in the operation of a plurality of different kinds of selector switches (group selectors, final selectors, P. B. X final selectors) which is arranged in response to a series of impulses to exert a series of controls over difierent circuits which are capable of operating a plurality of different kinds of selector which may then be connected up,'a specific operation for each kind of selector switch being solely dependent upon the individual circuits of the selector switch which is being operated.
  • selector switches group selectors, final selectors, P. B. X final selectors
  • the magnets from the conversational leads is effected without the employment of any relay or any like independently operated device.
  • the magnet of a selector switch which is first operated is maintained operated after responding to the first series of impulses for'the first motion of the selector, while a second magnet is subsequently opera-ted to control the second motion of the selector, a third magnet which eventually controls the release of the selector being'employed for completing a circuit to the second magnet.
  • a selector circuit is provided'in which one magnet is normally connected to an incomingilead andsuhsequently during the operation of ,aswitch and on release other magnets are connected to the same or other incoming'leads over which leads the operation of the switch is efiected without the intermediary of any relays.
  • a telephone installation comprises a control relay set adapted to control the successive operation of switches in a train, switch mechanisms with control circuits of the same standard design, contact banks, cablinginterconnecting theindividual to the contact banks and having dis-g criminating means associated therewith such;
  • control relay set in conjunction with the standard circuits of the switch mechanism is adapted to cause the switch mechanism to function in the manner determined by the discriminating means whereby the same switch mechanism and its individual circuits may serve for a plurality of different kinds of switches (group selectors, final selectors, P. B. X'final selectors).
  • a selector switch comprises two readily separable parts, the contact bank and the controlling mechanism, each having circuit wiring to and including contact-making devices'an'd the jack-in arrangement by which the circuit wiring of the two parts is joined when the controlling mechanism is correctly connected up to the contact bank,
  • a a selector circuit for switches having pairs of co operating contacts in their contact banks is so a :Set of co-operating contacts having connections onthe incoming sidel adapted for use with the'particular groupof outgoing lines selected.
  • Fig. 1 shows the operative circuits of a 19 level 10 outlet per level (10/10) earth testing group selector
  • Fig. 2- shows at the" left the basic control circuit therefor and at the right'the bank wiring of a'group selector.
  • Fig. 3 shows circuits of a 101/ 10 battery testing group selector.
  • Fig. 3-A shows the bank wiring or a group selector.
  • Fig. 4 shows circuits of a 10/10 regular final selector and Fig. 5'shows circuits of a 2-10 line P. B. X Ill/l0 final selector.
  • Fig. 6 shows circuits of the control relay set for a'train of group' selector and fiinal selector switches.
  • Fig. '7 shows' circuits of the switching arrangemerits for outgoing selector levels.
  • Fig. 8"' shows a typical switch train embodying the circuits shown in Figs. 3 to inclusive.
  • a slow tof-releas e relay is shown with a hatched portion at loneend of the rectangle indicative thereof, fwhile; a slow-to-operate relay is shown with a cross at one'iend, such a relay being in some instancesslow-to-release as well as slowto-operjat'ef
  • the construction ofswitch to which the cir-" contacts Of the four comb plates provided for each set of four rows two correspond to the incoming conversational leads, a third to the incoming private or test lead and the fourth to an auxiliary lead.
  • FIG. 1 the operating circuits for the switch mechanism which controls these contacts, among others, are shown in Fig. 1.
  • the only controls to reach this switch mechanism come overrthe four incoming conductors, the operating circuits for the switch 2 being connected to said conductors (and to battery and earth potentials, as well) by means of 7 a six point jack. It will be seen that the speaking path passes through neither relay contacts nor jack-in plug and socket points.
  • the holding and battery feeding bridge shall be in the first stage or at least in an early position in the train.
  • the avoidance of line contacts means that selectors provided with two-0r more sets of wiper arms and banks should not be provided as these need switching relays so that generally there will be'only one available outlet per step on any level such as on a 100 outlet (ten levels of ten outlets each) selector and it is proposed to use such a 100 outlet selector in the new system.
  • the new selector drive arrangements may, however, enable a secondary movement search speed to be obtained, which will permit of fifteen or more outlets to be hunted over in a direct line.
  • the use of such selectors also permits four wires to be used and this fourth wire is made use of to simplify subsequent circuit design. It also simplifies the circuit problems which arise when a feeding bridge is employed at any early stage in the switch train.
  • the use of the fourth wire opens up the possibility of avoiding the use of independent relays in the selectors.
  • the primary and secondary magnets may be used as relays, since they can conveniently be of the same general design as the standard British post ofiice type relays.
  • Every selector normally contains three basic relays usually designated A, B and C.
  • the present circuits are such that these relays need be provided only once per train thus further justifying the use of 100 outlet selectors and effecting material economies in relays.
  • One of the problems created by employing the battery feeding relays at an early stage in the connection is that of impulsing.
  • the relays usually subject to impulse failure are concentrated in the first stage so no difference is encountered there.
  • the magnets are subject to an initial extra repetition due to this cause, but in any case, this is met by the elimination of a repetition in the selectors themselves where the incoming impulses are delivered direct into the magnets instead of being repeated from an A relay.
  • the magnets are selfcorrecting and will perform a single operation on one pulse however long or short.
  • th basic control circuit shown on the left in Fig. 2 is permanently associated with the contact bank of the first group selector shown in Fig. 1; it controls not only this selector, however, but also all switches at subsequent stages in the switch train.
  • the combined primary magnet and relay VR (Fig. 1) is impulsed from the control relay set over the negative line, only one step being taken by the switch for each up and down movement of said primary magnet.
  • the Z wire is used for primary/secondary changeover, which is brought about by the combined release magnet and relay ZR.
  • the switch is maintained from the private conductor P and serves as a switch holding relay; on its release at the end of the call it reenergizes release magnet ZR to initiate release of the switch. Since the switch is to function as a group selector, i. e. with dialled primary movement and self-driven secondary movement, and is to be controlled from a simple control circuit such as that of Fig. 2, then the primary driving cam will have to be of the two-stage escapement release type while the secondary driving cam will have to be of the single stage simple release type.
  • Relay A therein operates, followed by relay B, whereupon the selector switch permanently associated with the control relay set is prepared for operation by the extension of earth forward over the negative and P leads.
  • the earth on the negative lead operates the primary control relay VR, corresponding to relay M in the aforementioned application Ser. No. 478,242, which at contacts ml prepares a locking circuit for itself on to the private P.
  • the armature extension on relay VR allows the associated driving cam to rotate slightly to the second stop position and when relay A drops at the beginning of the first impulse relay VR releases in turn and frees the driving cam.
  • relay A Under local spring pressure it rotates further and engages with the roller and thereupon completes a revolution independently of the control relay VR as already described.
  • the release of relay A at the beginning of the first impulse also causes contact :12 to energize relay C.
  • the primary carriage On the next and subsequentimpulses of the train the primary carriage is operated in a similar manner to cause it to advance a number of steps corresponding to the digit dialled and it will be noted from Fig. 2 that relays B and C are held operated throughout the train by virtue of their slugs, the B relay guarding the connection and maintaining the P lead earthed while the C relay maintains the Z lead open to prevent the premature operation of the release relay ZR which is connected up to the Z lead on the first primary step due to the mechanical operation of the switch off normal contacts NI. 7
  • relay ZR which lifts the wipers clear of the bank level in question and at contact 272 provides an operating circuit for the secondary control relay RR.
  • This relay in operating locks relay ZR at contacts rrl and also releases the catch on the secondary driving cam which engages with the roller. Thereupon, since in this case the catch arrangement. between the extension of the secondary relay armature and the driving cam is not of the escapement type, then until such time as the motion of the cam can be halted by the release of the relay RR.
  • the cam will continue to be rotated by both the driving roller and also periodically under control of its local drive-engaging spring. This will cause the secondary carriage to advance step-by-step and carry with it the primary carriage; thus the wiper arms secured thereto are caused to enter stepby-step into the selected bank level.
  • the secondary off-normal contacts NR! and NR2 are mechanically operated so that the holding circuit of relay VB is transferred to the P lead at contact NR2 and is locked for the remainder of the call via resistance VRR.
  • relay RR At the end of each secondary step the operating circuit of relay RR is broken by the interrupter contacts rl, which it will be understood are made during the engagement of the secondary driving pawl with the secondary ratchet, but when this occurs it will be noticed that the second winding of this relay will be connected over a rubbing test wiper P on to the corresponding lead of an outgoing trunk. If such a lead is busy an earth po- I tential will be encountered thereon so that relay RR will remain held and the secondary carriage will step on to the next set *of outlets.
  • the wipers will advance to the 11th step position in which position the 11th step contacts SI will be mechanically operated and will open the circuit of relay RR to halt the secondary motion in the same manner as for a free outlet so that the switch will contact the control relay set through to the 11th set of bank contacts.
  • the 11th step positive contact is permanently earthed so that earth will be extended back over the positive lead to the control group which in response thereto will initiate the return of a busy tone to the calling party in a manner discussed in the previously mentioned application. If an overflow for the level is to be provided this could be connected to the 11th step P contacts and the contacts SI in operating could v be in the form of a changeover combination tor in the same manner as previously described;
  • relays A and B in the control relay set will release and the removal of earth from the P lead will release relay VR, whereupon an operating circuit for relay ZR is re-completed via contacts m2 and NHL bank and as previously described, the primary and secondary carriages are now freed to restore The wipers are again lifted clear of the a adapted to extend earth forward over the rub bing P wiper to operate the overflow meter in this condition.
  • FIG. 8 A typical switch train including these units in their proper relationship is shown in Fig. 8. It will be observed that the final selector in the switch train may be astandard one employing the circuits shown in Fig. 4' or may be a P. B. X
  • the switch train may include, between V the first group selector and the final selector, one f or more additional group selectors identical to the one shown.
  • the group selector may be omitted, the.
  • the speed timing circuit comprises a single time measuring circuit including a condenser QD, resistance Y and neon tube NT and is adapted to compare the total length of the makeeplusbreak period of each impulse of a received train with a predetermined period of the order of 150 milliseconds which is substantially equal to total length of each impulse at the lowest impulsing speed tolerated in practice.
  • the circuit is set into operation at the beginning of the first-impulse of a train and is restored to normal by each successive impulse of the train until the last pulse is received, after which it functions either to initiate release of the connection or to render the circuit of the switch in question ready for the further function required'of it according as to whether the impulse train finished with the impulse accepting relay normal or operated.
  • relay AA When a calling subscriber is connected through to the control group, relay AA operates, and at contacts aai brings up relay BB, while contacts aa2 rapidly charge up condenser QE to the exchange battery voltage via resistance YM.
  • Relay BB in operating at contacts b'b'l places aiguarding and holding earth on the incoming P lead and at contacts bb l extends earth potential out over the outgoing (right hand) negative lead to operate the primary relay IVR in the first "group selector associated with the control :group, the circuit for which is shown Fig. 3.
  • relay lVRin operating at contact 1121*! disconnects the idle resistance marking battery comprising the battery connected resistance YA which is normally connected to the P lead to indicate the free condition of the switch to a preceding hunting switch where such a switch is involved.
  • the armature extension of relay 'IVR allows the associated driving cam to rotate slightly to the "second stop position and the switch is now 'readyto receive a train of impulses.
  • relay BB in operating at 19192 connccts up dial tone-over'common lead DTE to the centre winding "of relay AA and the'dialtoneextends by induction on to the incoming speaking leads and thence to the calling party.
  • relay AA When relay AA releases on the first impulse-of a dialled train relay E energises in series with relay BB which is therebyheld.
  • RelayE in operating at cont-act e l brings up relay M'D which atcontacts md3 disconnects the dial tone circuit and locks via contactsmd-ldt and bet: to earth.
  • relay AA When relay AA re-operates at the end of the first impulse relay BB remains held Via relay E in parallel with resistance'YL, relay E-also remaining operated under this condition and at contacts aaz condenser 'QE is rapidly rechargedvia resistance YM.
  • the second break impulse of the train therefore re-operates relay HR for a short period in the same manner as for the first, andthe second momentary b-reakis made in the earth circuit over the negative lead to the selector relay 'IVR, whereupon a s'econds'tep is delivered to the selector, This happens for each succeeding impulse of the train until at the end of the train relay remains operated for the comparatively long-1 nterdigital pause period.
  • a charging circuit for the speed timing condenser 'QD is prepared at e3 via resistance YO to positive loattery and when reIayJHR releases after extending the momentary break impulse to the selector condenser QD starts to charge.
  • the respective values of the resistance and condenser are such that the condenser takes approximately milliseconds to reach a voltage large enough to flash the neon tube NT. More precisely, the charging period is 150 milliseconds less the operated time of relay HR which operates for fa, given time :period at commencement of the break period of each :recei'ved impulse.
  • Neon tube NT in flashing brings :up relay CC and this relay in operating Jocks over its upper winding in series with resistance and :62 and at its contactsccl disconnects 're'lay E which-commences to release slowly.
  • :At contacts ce-2 battery via the winding of relay D is ifed out along the Z wire and since the selector primary off-normal contact 4N2 will have closed when the switch stepped off normal in "a primary direction this battery potential extends through to the combined release -mag-net and relay IZR. Relays D and lzR operate under this condition,
  • Relay lRR in operating initiates the secondary drive by freeing'the catch on the secondary driving cam and locks relay ZR via contacts lrrl to battery Via resistance 'YC.
  • the secondary off normal contacts lNRl and INR2 are operated, the former disconnecting the initial operating circuit of relay lZR so that relay D in the control relay set releases without having effected any circuit operation at this stage; at contacts INRZ the holding circuit for relay IVR is transferred to the earthed P lead.
  • Contacts lzrZ connect the rubbing private test Wiper RWl through over the positive trunk and thence via resting contacts fl and M, operated contacts 005 and resistance YQ to the upper winding of the fast cut-drive relay HR.
  • relay HR rapidly operates and at contacts hr? disconnects the earth potential being fed out on to the negative lead, whereupon relay IRR releases to stop the switch motion and at contacts lrrl de-energises relay iZR to drop wipers into action with the banks so as to switch the control relay set through to the succeeding selector stage.
  • the control group relay H has not enough time to operate at this stage, for a reason to be later described.
  • the secondary drive interrupter contacts lrl function in thesame manner as for the earth testing group selector case previously described.
  • relay CC when relay CC is operated to initiate the secondary movement it remains locked either until the expiration of the slow release time of relay E when its locking circuit is opened at contacts e2 or of the time required to find a. free trunk when its locking circuit is opened by contacts hrl, whichever is the longer.
  • relay E will operate in series with relay BB whichholds. discharged through relay HR and a single impulse will therefore be sent out over the negative wire to the succeeding selector.
  • speed timing circuit will come into operation, whereupon relay CC operates and since relay AA is now normal the holding circuit of relays E and BB is disconnected and the former will commence to release slowly due to its slug while the latter will release comparatively slowly due to its non-inductive resistance shunt involving resistor YN.
  • relay BB On release of relay BB the locking circuit for relay CC is opened at bbl and on'release of relay E the holding earth is removed from the Condenser QE will be 12 P lead at e'l whereupon relay IVR which has been previously held is now released and at contacts lorZ completes a re-operating circuit for relay IZR, whereupon release of the group selector is effected in the same manner as for the previously described earth-testing group selector.
  • the interrupter contacts open and release the release relay, whereupon the incoming prove busy then the secondary movement will continue until the rubbing wiper RWI reaches the 11th step position, the P contact of which is permanently wired to a resistance battery so that the cut-drive relay HR will operate to release the secondary control relay IRR and so halt the rotarymotion.
  • Relay E will have released by this time and hence relay HR in operating will release relay CC and contacts hrl.
  • relay IRR in releasing releases relay IZR and the 11th step contacts ISI thereupon become effective to extend earth back over i the positive lead to bring up relay G in the control group.
  • Relay G in operating looks over its contacts gl and at contacts g2 connects up a busy tone earth source over common lead BRE to the centre winding of relay AA from whence it is returned to the calling party.
  • the 11th step P contact the outgoing P contact of which is permanently wired to resistance battery it will be understood that the incoming P contact of the bank switching pair will have been removed so that when the wiper arm is dropped on the release of relay I ZR the outgoing contact will not be earthed from the control relay set and further selectors can therefore switch to the same battery.
  • the 11th step contacts ISI On the release of relay IZR the 11th step contacts ISI also become effective to extend earth to an overflow meter which will be connected to the 11th step outgoing positive bank contacts,
  • control set is governing the setting of a group selector; under conditions where the control set is governing the setting of a final selector relay H will be given ample time to operate as will be later described.
  • Relay 2ZR in operating connects the secondary relay 2RR up to the earthed negative lead, but in this instance since relay ZRR. is connected to earth instead of battery it will remain normal due to the shunting action of the earth on the negative lead, which earth also serves to hold the vertical relay ZVR. Hence no automatic secondary movement takes place and the control group relay D remains held in series with relay ZZR.
  • each time relay HR operates for a short period at commencement of the break period of an impulse the earth potential to the negative lead is replaced by a battery potential via resistance YP and the selector secondary relay ZRR for each received impulse, is operated for a length of time governed by the operated time of relay HR.
  • the secondary driving cam is of the simple catch release type and hence in order that dialled impulses may be effective thereon it is necessary to ensure that the control relay 2BR after having been operated in response to an impulse shall release in time to put a stop in the path of the secondary cam before this cam has completed the one half revolution necessary to advance the wipers through one step; for this purpose the length of the secondary pulse as governed by relay HR is ar-' ranged to be less than the 30 millisecond period required by the cam to complete one half revolution. Each successive pulse is similar to the first and the carriage is thus dialled step by step into the bank.
  • relay CO In the control group at the end of the first impulse train relay CO in operating initiates the slow release of relay E in usual manner, while relay BB remains held.
  • One locking circuit of 14 relay CC is opened by operated contacts dl so that when relay E releases after its slow release period relay CC will immediately restore and the circuit is now in readiness for the next dialled digit.
  • relay CC When relay CC again operates at the end of this next digit the earthed testing relay HR and the switching relayHare connected up in series over the positive wire and thence via contacts 2zr'2 and the rubbing private testing wiper RWI to the called subscribers P conductor.
  • Contacts MI and h! respectively, connect up an earthed ringing generator GNR via the winding of relay F on to the negative line and a ringing return battery via lead RRB and resistance YS on to the positive line so as to ring the called partys bell, while contacts hZ connect up a ringing tone earth source over lead RTE to the centre winding of relay AA from whence the ringing tone returns to the calling party.
  • relay MD was operated from relay E when the latter operated in response to the first train of impulses received by the control group and when relay D operates it will be seen that the holding circuit for relay MD is opened at contacts d3. On release of relay MD after its slow release period a battery potential via resistance YK is extended backwardly over the metering lead M to register the call against the calling party.
  • relay E operates in series with relay BB which holds.
  • the speed timing circuit comes into operation and milliseconds after release of relay "AA relay CC" comes in and initiates the slow release of relays E and BB.
  • relay BB relays H, F and D are released, while on release of relay E the holding earth is removed from the P lead and the various primary control relays in the selector train which have been held therefrom are released so as to bring up their release relays and so initiate release of their respective switches.
  • relay H will fail to operate during the release time of relay E and when relay E releases relay CC will fall and will connect up relay G on to the positive lead.
  • Relay G thereupon operates to the earthed busy subscribers privateencountered by rubbing wiper RWI and returns busy tone to the calling party at contacts 92, while at contacts g4 the circuit for extendin battery potential via the winding of relay D on to the 2 lead is opened and --the final selector release relay 22R thereupon releases.
  • the final selector wiper arms are thereupon lowered into contact with the bank but it will be appreciated that interf erencewith the busyrequired subscriber is guarded against by the disconnection in the control group of the negative, positive, and Z wires at contacts g5, and g4 respectively, which wires are, in the case of all final selector switches, respectively connected up at the final selector switch banks to the subscribers negative, positive and P leads.
  • the P lead from the control group and through the selector train to the final selector remains earthed for the purpose of holding the selector train until the calling party hangs up, and since the P lead does not extend through to the subscribers line circuit it can do so without intereference to the line of required subscriber.
  • the auxiliary bank which is only used for testing purposes may comprise the outgoing P bank contacts which on the final selector are normally unwired while the outgoing Z contacts connect through to the subscribers privates.
  • the first lines of P. B. X groups are marked by a source of battery with alternating current imposed, on intermediate lines the outgoing P and Z contacts are strapped, while on the last lines a resistance battery is connected.
  • the switch wipers are positioned to the first line of a P. B. X group the battery connected alternating current source encountered by wiper RWZ extends back via condenser QA and the Z lead to operate relay HS on its left hand winding 16 in series with resistance YP, this winding of relay HS being arranged in association with condenser QF and rectifier MRA so as to operate satisfactorily on alternating current.
  • Relay HS 'in operating at contacts hsZ maintains a holding circuit for relay E so that relay CC in-turn will remain locked after operation from the speed timing circuit, while at contacts hsl it prepares for the extension of battery potential via its other winding on to the negative lead.
  • relay HS in operating after the operation of relay HR will, in a manner as already described in connection with the regular final selector, cause the P. B. X final selector to switch through to the first line on the P. B. X group after which ringing is carried out in the manner already described.
  • relay HR will fail to operate and the resistancebattery extended on to the negative line via the right hand winding of relay HS will bring up the selector secondary relay 3BR to cause the switch to hunt automatically over the lines in the group.
  • relay 3BR With relay 3BR. operated it will be noted that at contacts 3TT
  • Relay HR in operating at contact h13 opens the last subscriber in the group so that if the line is free relay H will operate to effect connection with the called line. If the line is busy relayH will fail to operate but relay HR. will remain held over its lower winding to battery via resistance YM. On release of relay El after its slow release period relay CC will fail and will release relay HR, while'at contacts cs5 relay G will be 'conn m A. 11*; .iJi 4i nected up. to the positive lead and will then operatetoi the busy earth potential encountered, by the busy test wiper RWl' with results as already described.
  • circuit of Fig. can be used for a switch to function as Well as either a group selector, final selector or P.
  • B. X final selector by simply'making appropriate connection to the contacts engaged by the rubbing Wipers and in the case of a group selector arranging that the rubbing wipers RWZ engage a normal contact connected to alternating current supplied in series with battery as in the case of the first contact of a group.
  • theoutgoing'Z bank contacts in the final selectors connect with the P conductors of the subscribers line circuits concerned so that when the control group switches through earth will be extended forward over the Z wire from contacts M to the P conductor of the subscriber in question.
  • the Z wire is carried through between the control group and the final selector without shunt or series resistances, so that various facilities such as toll breakdown which were originally provided from. the final selector can nowbe provided in the control group.
  • relay- ZZR will be operated as previously, and the control group will be arranged to extend a resistance battery out over the negative lead to operate relay 2RR via contacts of which the primary relay 2VR will be maintained temporarily until the secondary drive commences and the operation of relay 2BR. will cause the secondary drive-to take place.
  • the cutdrive relay HR will operate through the positive lead as before and will thereupon open the negative lead to drop relay ZRR and in this instance the Z wire will be also opened by contacts of re- 18 lay RR to. release relay ZZR and so effect switching through to'the succeeding switch.
  • the control group will be working into afinal selector it, will operate almost exactly as shown and described.
  • relay [RR is connected in one case to battery potentialand 2BR is connected to earth potential if the winding. of IRR or 2BR was connected to a pin of the jack and engaged with a terminal in the contact bank. This terminal could be connected to earth in the case of a final selector and battery in the case of a group selector.
  • Discrimination inthe first case. may be eifectedby means such as a resistance inserted at the jack of the group selector andnot at the jack of the final selector or vice versa.
  • a group'selector could furthermore be adaptedto operate in the same manner as a P. B. X final selector, i. e., with an initial dialled secondary movement, andthis facility might be used in. connection with testing and routining functions and for special trunking arrangements.
  • the selector can either start tohunt from the first bank contacts or can be dialled to a position on the bank and be caused to hunt on from there.
  • switches according to the invention can be rendered self-routining, since each selector can derive from the driving roller-the requisite trains of impluses at the raterof ten per second.
  • An unlocking push button at the front of the selector could apply the impulses to' the primary control relay in response to which? the switch would; step in a primary directiongto say level 9, where mechanically operatedsprings would energise the release relay to cause the switch to perform a secondary hunting movement until contact 9 on this level is reached. Further springs would then be operated to halt theswitchmovement.
  • P. B. X groups having more than ten lines.
  • Such large P. B. X groups are the exception rather than the rule. posed to employ selecting units catering for up to 100.1ines: and which by virtue of the use of one or; more subsidiaryrelays are capableof performing hunting operations over a level, then of being In these. cases it is pro- 19- released backagain to the commencement of the level and stepped up to the next level where they perform another hunting operation, and so on; a method of achieving secondary release without primary release bein described previously.
  • a facility which has not yet been described in connection with the control group is that of switching out the transmission bridge when the call is to be routed over an outgoing junction. This'can be done in a simple manner which will involve relay contacts in the through leads but the following method now to be described in connection with Fig. '7 in which relay contacts in the through speaking leads to the outgoing junction repeater relay sets are entirely avoided, is proposed.
  • an automatic switch having access to a plurality of lines and adapted to take a step by step primary movement followed by a step by step secondary movement in order to select a particular one of said lines; control equipment; an impulsing circuit extending from said control equipment to said switch; a circuitextending from said control equipment tosaid switch for causing said.
  • the comb plate wiring may be 7 split so that the incoming speakingleads will connect via contacts og3 and og4 of a relay 0G via the control group of Fig. 6 with the comb plates 1-9 and will connect directly with the comb plates of level 0.
  • relay 0G When afree outgoing repeater-is found, relay 0G will be operated from earthedcontacts bb of the control group relay BB over its left hand low resistance winding to the idle resistancemarkin battery which will be connected to the incoming Plead at the outgoing repeater; the low resistance winding of relay 0G serving as a guardin potential and also to operate relay 0G which thereupon at contact 093 and og4 disconnects the circuit to the control group.
  • the subscribers loop will be extended forwardto operate the impulse accepting relay IA and in turn the guard relay IB in the outgoing relay set and a guardin and holding earth will be extended back to hold relay 0G on its other winding, be-
  • relay'BB in the control group which has previously been holding it, releases.
  • the subscriber will now be directly connected through to the outgoing repeater which will receive the remainder of the trains of impulses to be dialled and which will provide the battery feed to the calling subscriber.
  • the selector will of course remain held over the P lead from earth at the outgoing? relay setwhi'ch will extend via contacts 0g2 and through the control group to the selector primary control relay.
  • Theiabove arrangement can also apply to the case where the group selector has only one level giving access to the local switches in the exchange and'th'e other levels all have access to ment at other times is a hunting movement controlled by said switch.
  • two automatic switches each having access to a plurality of lines and each adapted to move step by step in a primary direction and then step by step in a secondary direction in order to select a particular one of said lines
  • common control equipment connected to one of said switches at times over a set of conductors outgoing from said equipment and connected to the other one of said switches at other times over the same set of conductors over from its primary movement to its secondary movement
  • means including said circuits whereby each step of both said movements of one of said switches is always directed, by said equipment, whereby each step of both said move-- ments of the other said switch is sometimes directed by said equipment and whereby one of said movements of said other switch sometimes is a self-controlled hunting movement.
  • a plurality of automatic switches each having access to a plurality of lines and each adapted to move step by step in a primary direction and then step by step in a secondary direction in order to select a particular one of said lines, common control equipment connected to the difierent ones of said switches at difierent times over the same set of conductors outgoing from said equipment, an impulsing circuit extending over certain of said conductors to the connected switch at each of said times, another circuit extending over certain of said conductors to the connected switch at each of said times for causing the connected switch to change over from its primary movement to its secondary movement, means including said circuits whereby each step of the primary movement of the connected switch always is directed by said equipment and the secondary movement of the connected switch is a hunting movement controlled by that switch, and a third circuit extending over certain of said conductors at each of said times for testing the lines encountered by said switch during said hunting movement.
  • two automatic switches each having access to a plurality of lines and each adapted to move step by step in a primary direction and then step by step in a secondary direction in order to select a particular oneof said lines, common control equipment connected to one. of said switches at times over.
  • a control unit for controlling each switch in turn to extend the connection to the next switch in said trainf said connection including a first circuit outgoing from said unit over which impulses are transmitted to each switch in turn tomove that switch step by step, a second circuit outgoing from said unit for operating each switch in turn to change over from its primary movement to its secondary movement, and a third circuit outgoing from said unit for testing the condition of each switch to which said connection is extended by a preceding switch in said train,
  • a selector switch a plurality of groups of connector switches accessible to said selector switch, a plurality of groups of lines accessible to each of said connector switches, control equipment, a connection outgoing from said equipment to said selector switch, means in said equipment for operating said selector switch directively over said connection to select a particular group of said connector switches, means for then causing said selector switch to commence hunting for an idle connector switch in the selected group, testing means in said equipment operated over said connection when an idle connector switch is found for causing said selector switch to halt said hunting operation, seize the idle connector switch and extendsaid connection to the seized connector switch, said first.
  • a selector switch In a switching system, a selector switch,.a.
  • a selector switch a plurality of groups of connector switches accessiblev to said selector switch, a plurality of groups oilines accessible to each of said connector switches, control equipment, three circuits outgoing from said control equipment to said selector switch, means in said equipment for transmitting impulses over the first of said circuits to operate said selector switch directively to select a particular group of connector switches, means in said selector switch then controlled by said equipment over-the second of said circuits for causing said selector switch to commence hunting for an idle connector switch in the selected group, means in saidequipment operated over the third of said circuits when an idle connector switch is foundfor'causing said selector switch to halt its hunting operation, seize the idle (connector switch and extendsaicl' three circuits to the seized connector switch, said first means then operated to transmit impulses over said first circuit to operate the seized connector switch directively to select a particular group of lines among the groups accessible to that connector switch, means in said connector switch operated over said second circuit by said equipment after said group of lines has
  • connection is extended progressively through a plurality of switching stages, equipment common to said stages for controlling the extension of said connection, a two motion switch at each stage connected in turn to the same set of control conductors outgoing from said equipment, said set comprising only an impulsing conductor, a guard conductor, a changeover conductor and a test conductor,
  • a control unit common to said switches for controlling each switch in turn to extend the connection to the next switch in said train, a stepping magnet in one of said switches controlled by said unit to operate said one switch step by step in one direction, a second magnet controlled by said unit for operating said one switch in another direction, and means for maintaining said stepping magnet energized during the operation of said one switch in said other direction.
  • a control unit common to said switches for controlling each switch in turn to extend the connection to the next switch in said train, 'a stepping magnet in one of said switches controlled by said unit to operate said one switch step by step in one direction, a second magnet, a third magnet controlled by said unit after the operation of said switch in said one direction for connecting said second magnet to said unit, said second magnet then controlled by said unit for operating said one switch in another direction, and means for maintaining said stepping magnet energized during the operation of said one switch in said other direction.
  • a primary stepping magnet in each switch connected to said conversational circuit and controlled thereover to operate that switch in one direction
  • a secondary stepping magnet in each switch connected to said conversational circuit and controlled thereover to operate that switch in a different direction
  • a primary switch having access to a plurality of secondary switches, means for transmitting impulses alternating in polarity, impulse receiving means in said primary switch responsive only to the impulses of one polarity for operating said primary switch directively to connect with a particular one of said secondary switches, and impulse receiving means in the seized secondary switch responsive only to the impulses of the other polarity for then operating said seized secondary switch directively.
  • a pair of numerical switches in serial relationship to one another, control equipment common to said switches, means in said equipment for transmitting impulses of one character to operate one of said switches 24 directively and for transmitting impulses of a different character to operate the other of said switches directively.
  • a switching system a plurality of switches, control equipment common to said switches, said equipment having outgoing conductors which are connected in an identical way to different ones of said switches at different times, means in said equipment for impressing voltages of two diiferent characters alternately upon one of said conductors, impulse receiving means in a connected oneof said switches responsive only to the voltage of one of said characters impressed upon said one conductor for operating that switch directively, changeover means in said connected switch operated over another of said conductors after said directive operation of said switch, means in the connected switch thereupon connected to said one conductor and responsive only to voltage of the other of said characters impressed thereon for controlling a secondary movement of the connected switch.
  • a switching system a plurality of switches, control equipment common to said switches, said equipment having outgoing conductors which are connected in an identical way to difierent ones of said switches at different times, means in said equipment for impressing voltages of two different characters alternately upon one of said conductors, impulse receiving means in each of said switches effective when that switch is connected to said conductors to respond only to the voltage of one of said characters impressed upon said one conductor thereby to impart to that switch a directive primary movement, other means in each of said switches connected to said one conductor after the directive primary movementof that switch, said other means in one of said switches being responsive only to voltage said one character impressed upon said conductor thereby to impart to said one switch a hunting secondary movement, and said other means in another of said switches being responsive only to voltage of the other of said characters thereby toimpart to said other switch a directive secondary movement.
  • control apparatus having a plurality of conductors outgoing therefrom, a plurality of switch units each including not more than three electromagnetic devices, means including a jack for detachably connecting each one of said units to said conductors at times, a plurality of lines accessible to the connected switch unit at each of said times, and means in said apparatus operated for controlling the three electromagnetic devices of the connected switch unit to impart to that switch unit a variable primary movement and a variable secondary movement, thereby to select one of the lines accessible to said. switch unit.
  • control apparatus having a plurality of conductors outgoing there from, a plurality of switch units each including not more than three electromagnetic devices, means including a jack for detachably connectin -..each one-of said units to said conductors at times, a plurality of lines accessible to the connected switch unit at each of said times, and means in said apparatus operated for controlling the three electromagnetic devices of the connected switch unit to impart to that switch unit a variable directive movement followed by a hunting movement, thereby to select one of the lines accessible to said switch unit.
  • a plurality of two motion switches each having electromagnets for exerting mechanical forces upon the switch mechanism to operate same, electrical contacts also operated mechanically by the same electromagnets, circuits individual to each switch controlled by said contacts, and a control unit common tosaid switches for cooperating with the said electromagnets and contacts of each switch at times to operate that switch :in two directions without the aid of any other electromagnetic device individual to said switch.
  • a plurality of switches each having electromagnets for exerting mechanical forces upon the switch mechanism to operate same, electrical contacts also operated mechanically by the same electromagnets, circuits individual to each switch controlled by said contacts, and a control unit common to said switches for cooperating with the said electromagnets and contacts of each switch at times to operate that switch successively in three different directions without the aid of any other electromagnetic device individual to said switch.
  • a switching system a plurality of switches each having electromagnets for exerting mechanical forces upon the switch mechanism to operate same, electrical contacts also operated mechanically by the same electromagnets, circuits individual to each switch controlled by said contacts, and a control unit common to said switches for cooperating with the said electromagnets and contacts of each switch at times to operate that switch successively in four different directions without the aid of any other electro magnetic device individual to said switch.
  • each contact set having two parts which normally are not in electrical connection with one another, a plurality of outgoing lines corresponding respectively to the different ones of said contact sets, each line being connected to one part of its corresponding contact set, an incoming line connected in multiple to the other part of every contact set in certain of said groups, another incoming line connected in multiple to the other part of every contact set in other of said groups, contact controlling apparatus, means in said apparatus for receiving difierent digits at diirerent times and for-selecting a contact set in a diiferentone of said groups at eachof said times, the group in which a contact set is selected at each of said times depending upon the value of the digit received,- and means in said apparatusoperatedateach oisaid times after a contact set has been selected for completin an electrical connection between the two saidparts of said selected contact set.
  • a switch in .one exchange having a plurality 0f groups of contact sets, each contact set having two parts which normally are :not in electrical connection with one :another, a plurality of trunk lines outgoing :from :said one exchange to connect with another exchange, said lines -:corresponding .re- "spectively :to the differenteontact sets in certain of said groups, a plurality of lines local "to said one exchange, said dast llines corresponding respectively :to the different contact sets in :other of said :groups,.each said outgoing line and each said local line being connected to one part of its corresponding contact set, one line incoming to said switch and connected in multiple to the other part of every contact set in said certain groups, another line incoming to said switch and connected in multiple to the other part of every contact in said other groups, contact controlling apparatus, means in said apparatus for receiving different digits at different times and for selecting a contact set in a different one of said groups at each of said times, the
  • a plurality of groups of contact sets each contact set having two parts which normally are not in electrical connection with one another, a plurality of out-going lines corresponding respectively to the different ones of said contact sets, each line being connected to one part of its corresponding contact set, a repeater, an incoming line connected directly in multiple to the other part of every contact set in certain of said groups and connected via said repeater in multiple to the other part of every contact set in other of said groups, contact controlling apparatus, means in said apparatus for receiving diiferent digits at different times and for selecting a contact set in a different one of said groups at each of said times, the group in which a contact set is selected at each of said times depending upon the value of the digit received, and means in said apparatus operated at each of said times after a contact set has been selected for completing an electrical connection between the two said parts of said selected contact set.
  • an exchange In a telephone system, an exchange, a selective switch in said exchange having access to local lirTes and to outgoing lines, control equipment, a conversational circuit incoming ,to said 27' in series tothe seized local line, and means controlled at-said other times to disconnect said incoming'conversational circuit from said control equipment and connect it through said switch independently of said control equipment to the seized outgoing line.
  • an exchange In a switching system, an exchange, a selective switch in said exchange having access to local lines and to outgoing lines, a repeater, a circuit incoming to said repeater over which impulses indicativeoi a local call are received at times and over which impulses indicative of an outgoing call are received at other times, means in said repeater for repeating part of the receivedimpulses to said switch, whereby.
  • said switch is effective to seize a local line at said first times and to seize an outgoing line at other times,.said means in said repeater then operated at said first times to repeat the balance of said received impulses over said switch and the seized local line, means controlled at said other times after said switch has been operated to seize an outgoing line for disconnecting said incomin circuit from said repeater and connecting it through said switch directly to the seized outgoing line, whereby the balance of said received impulses are conducted from said incoming circuit directly over said switch and said outgoing line without repetition.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Telephonic Communication Services (AREA)
US478243A 1942-04-20 1943-03-06 Selector operating circuit for use in automatic telephone systems Expired - Lifetime US2422285A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB247351X 1942-04-20

Publications (1)

Publication Number Publication Date
US2422285A true US2422285A (en) 1947-06-17

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ID=10216422

Family Applications (1)

Application Number Title Priority Date Filing Date
US478243A Expired - Lifetime US2422285A (en) 1942-04-20 1943-03-06 Selector operating circuit for use in automatic telephone systems

Country Status (5)

Country Link
US (1) US2422285A (enrdf_load_stackoverflow)
CH (2) CH247351A (enrdf_load_stackoverflow)
FR (1) FR933089A (enrdf_load_stackoverflow)
GB (1) GB556920A (enrdf_load_stackoverflow)
NL (1) NL71148C (enrdf_load_stackoverflow)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1463972A (en) * 1923-08-07 Automatic telephone system
US1503923A (en) * 1918-05-06 1924-08-05 Stromberg Carlson Telephone Telephone switching system
US2058216A (en) * 1935-05-11 1936-10-20 Bell Telephone Labor Inc Signaling system
US2090205A (en) * 1934-06-21 1937-08-17 Siemens Brothers & Co Ltd Electric remote control system
US2166329A (en) * 1936-01-29 1939-07-18 Ass Telephone & Telegraph Co Telephone system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1463972A (en) * 1923-08-07 Automatic telephone system
US1503923A (en) * 1918-05-06 1924-08-05 Stromberg Carlson Telephone Telephone switching system
US2090205A (en) * 1934-06-21 1937-08-17 Siemens Brothers & Co Ltd Electric remote control system
US2058216A (en) * 1935-05-11 1936-10-20 Bell Telephone Labor Inc Signaling system
US2166329A (en) * 1936-01-29 1939-07-18 Ass Telephone & Telegraph Co Telephone system

Also Published As

Publication number Publication date
FR933089A (fr) 1948-04-09
NL71148C (enrdf_load_stackoverflow)
CH247351A (fr) 1947-02-28
GB556920A (en) 1943-10-27
CH251036A (fr) 1947-09-30

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