US1903837A - Telephone system - Google Patents

Telephone system Download PDF

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Publication number
US1903837A
US1903837A US543759A US54275931A US1903837A US 1903837 A US1903837 A US 1903837A US 543759 A US543759 A US 543759A US 54275931 A US54275931 A US 54275931A US 1903837 A US1903837 A US 1903837A
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Prior art keywords
relay
line
circuit
conductor
switch
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US543759A
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Rodney G Richardson
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Associated Electric Laboratories Inc
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Associated Electric Laboratories Inc
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Priority to US543759A priority patent/US1903837A/en
Priority to DER83678D priority patent/DE649103C/de
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements

Definitions

  • the present invention relates to telephone systems in general, but is concerned more particularly with telephone systems employing automatic switches .to set up desired connections; and the main object is the'production of new and improved circuit arrangements in automatic switches for efiecting the' necessary. testing operations over one of the talking conductors and forcontrolling the release of, the automatic switches over one of the talking conductors, thereby. eliminating the test. and holding conductor ordinarily provided between successive automatic switches in an established connection and eliminating also the corresponding -wipare or brushes on the automatic switches themselves.
  • the arrangement disclosed herein is intended to avoid these difliculties by employing vacuum tubes tomake theneoessary tests byway v of their, grid elements and-tb control the releasing operations by having their grid elements connected to the talking circuits. It will be understood, of course, that the" 'd element of a vacuum tubedoes, not or arily consume an appreciable amount of current from the circuit to which it is connected,
  • An additional object is to. provide suitable circuit arrangements in the automatic switches so that a vacuum tube may be used :to respond to the controlling impulses received from the calling line-and repeat them to the o irating magnets of the switch, after which t fe'vacuumjtube is shifted into connection with one of the wipers of the to enable it-to be 'used to test trunk lines, as'
  • the talking conductors are reversed between the incoming conductors of the connector and the wipers thereof, so that the cut-off rela of the called line is on the opposite side 0 the established connection from the cut-off relay of the calling line, thereby making the two sides of the established talk-1 ing circuit symmetrical except for the slight di erence in location of the two cut-ofl relays and the impedance of the intervening porcircuit.
  • FIGs. 1 and 2 show suflicient automatic equipment for setting up a connection from the line of substation A1, Fig. 1, to the line of substation A2, Fig. 2, which equipment includes a line. finder LFl and ;a selector S1, Fig. 1, and a connector C1, Fig. 2.
  • Fig. 3 shows a modified line finder, selector, and connector which maybe used in setting up a connection from the line of substation A3 to the line of substation A4.
  • the 'finder, selector, and connector switches shown in the drawings are of the usual Strowger type, having their bank contacts arranged in ten levels, with ten sets of contacts in a level.
  • the selector S1, Fig. 1 is one of a group of selectors having access to ten groups of connectors, of which the connector C1, Fig. 2, is one of the connectors in the cup accessible by way of the third level of ank contacts of the selectors. .b'ince each connector group has access to amaximum of one hundred lines, the ultimate capacity of the system shown in the drawings is one thousand lines. It will be understood, of course, that this capacity can be increased to any desired extent by including as many selector groups as necessary, in which case an established connection includes two or more selectors instead of one selector as in the case of the disclosed switch train including the sglector S1.
  • a direct-current bridge is placed across the conductors 101 and 102 of his line, clos ng a circuit for line relay 103 of line circuit LCl.
  • Line relay 103 thereupon operates and places a ground potential at its upper armature upon conductor 105 which is multipled into the banks of all of the finders such as the finder LF1, and from which the conductor 105' extends to the bank multiple of the connectors having access to the line of substation A1.
  • the conductor 106 is s milarly multipled in the banks of all of the line finders in the group including the line finder LS1, and branch conductor 106 exhaving access to the line of substation A1.
  • line relay 103 closes a circuit for the second-level start relay 107, one of which is provided for each level of contacts in the banks of the finder LFl.
  • Relay 107 operates and at its right-hand armature places a ground potential on the second-level contact in the bank of the vertical test wiper 113, thereby marking the second level as the level in which the calling line is located.
  • Relay 107 also places ground potent al at its left-hand armature on the start conductor 130, thereby closing a circuit for the start relay of the first finder in the chain which happens to be idle.
  • start circuit extends to the start relay 122 therein.
  • Relay 122 accordingly operates.
  • start relay 122 When start relay 122 operates, it opens a point in the circuit of release magnet 117 and places ground potential on conductor 132, thereby preparing locking circuits for relays 123 and 124; starting the' vertical magnet 118 into operation, and lighting the filament of the vacuum tube 134 in series with resistances 116 and 115.
  • the symbols of a battery with a grounded positive pole and an ungrounded negative pole represent the regular exchange battery, of
  • relay 123 "is included in circuit with the ungroundedpositive pole of the plate bat-' the plateelementof the vacuum tube 114 and tery, but only anegligible current, orno currentat all, flows through the upper wind'ng ofrelay' l23-forthe time being, as the gri element thereofjis maintained at a negative relay 125 operates andwopens the circuit of magnet 118.
  • Relay 123 also disconnectsjthe-g 'ounded conductor 132 from'vertical magnet 1 18 and extends it to rotary magnet 119, thereby terminating the vertical testing movement with the wipers 111, 112 opposite'the calling level of bank contacts and initiating'the rotary movement to drive the wi rs 111, 112 over the contacts in'the selected evel.
  • At its upper armature relay 123 disconnects the grid element of vacuum tube 114 from the now-grounded verr 113 and extends it to the tical test wi wiper 111, w ich is used as a'test wi r during the rotary movement of the fin er.
  • Rotary magnet 119 and stepping relay 125 nowinter-act, causing the wipers 111and 112 to bedriven across the bank contacts in the selected level.
  • This rotary movement con: tinues uninterrupted until wipers 111 and 112 land upon theconta'cts terminating conduc tors 105 and 106.
  • vlviper on conductor 105-by relay 108 throng conv is not disturbed and the operation of, the ver- 111 encounters the ground potential tac ts of. relay 104.
  • the positive ground poture-of relayg,.123 causing plate current to lay 124'operates and a locking circuit .for its lower wind" at its inner lower con- .tacts and including t e grounded conductor winding of line rela 132.
  • Relay 124 also opens the circuit of the rotary magnet 119, stopping the rotary move- .ment with the wipers 111 and 112 in engagement with the bank contacts assigned to the line of substation A1.
  • relay 124 at its inner upper armature transfers the plate element of the vacuum tube 104 from its own upper winding to the windingof'relay 126; connects up the conductors 128 and'129 extending to the selector S1 at its upper armature and armature 134, disconnectin the resistance 127 at the contacts contro led by its upper armature.
  • relay 124 disconnects start lay 104 by way of wiper 112 and conductor 129, through the lower windin of line relay 141 of the selector S1.
  • Cut-o relay 104 accordingly operates and disconnects the conductors 101 and 102 of the calling line from line relay 103 and ground and extends them to the corresponding contacts in the bank of the linefinder by way of the bank-multiple conductors 105 and 106.
  • the conductors 101 and 102 of the calling line are thus extended to trunk conductors 120 and 129 incoiningto the selector S1, the connection including the upper armatures of relays 123 and 124, and the armature 134.
  • the calling line is now guarded against seizure by any one of the connectors having access thereto, as a positive potential is now applied to conductor 106 through the lower 141 and conductor 129.
  • relay 121 operates in series with the lower.
  • relay 121 When relay 121 operates, it
  • the potential of the filament of the tube 114 is more nearly the potential of the negative pole of the exchange battery, with the result that the potential normally assumed by the grid of the tube 114 by virtue of its connection to the negative conductor of the line is more positive than the potential of the filament of the vacuum tube because of the potential drop in the upper winding of the line relay of the selector S1 and re- Preparing the selector S1 for operation I
  • line relay 141 now energizes over the calling line and closes a lighting circuit for the filament of vacuum tube 151.
  • the resistances 150 and 149 in the filament circuits are of such relative values that the filament of the tube 151 is maintained very nearly as negative as the negative pole of the exchange battery.
  • relay 144 at its upper. armature, disconnects the grid element of tube 151 from the incoming conductor 128 and shifts it into connection with wiper 158 so .as to enable the negative trunk conductors of the trunk lines 1n the third level to be tested to determine the busy or idle condition of these trunk line s. Any engaged one of the trunk linesin the third level is identified by the relatively positive potential on its upper conductor owing to the potential drop in the relay winding supplying current to said conductor, while the idle trunk lines in the level are identified by the full negative potential of the exchange battery.
  • relay 146 for switching relay 146.
  • Relay 146 thereupon operates and closes a locking circuit-for itself to the grounded conductor 162 at its inner lower armature, at the same time opening its initial circuit,
  • relay 146 disconnects the incoming conductors 128 and- 129 from the windings of line relay 141 and extends them by way of wipers 158 and 159 to the conductors 160 and 161 extending to the connector 01.
  • the current which-flows from now on over the calling line is obtained over relay 201 of the connecter C1 and resistances 211. and 212, resulting-in a lowering ofthe potential on conductor 126', thereby marking the trunk line extending to the connector 01 as busy.
  • line relay 201 energizes over the calling line and over the incoming conductors 160 and 161 when this connector is seized by the selector S1, preparing a holding circuit for release relay 203 at its power armature and closing a li hting circuit for the filament of vacuum tu 213 at its upper armature.
  • the filament lighting circuit for tube 213 includes the high resistanee 213 and the low resistance 214, and these two resistances are so proportioned that the potential now impressed on the grid element of the tube is positive with respect to the potential on the filament, resulting in a flow of plate current from the ungrounded positive pole of the plate battery through plate relay 204.
  • Relay 204 operates and closes a circuit for release relay 203, whereupon release relay 203 operates and places ground potential on locking conductor 226 at its lower armature, thereby preparing the switch for operation as well as preparing locking circuits for relays 206, 208, and 210, and completing a lockm ta ts of relay 201.
  • the grid element of the vacuum tube 213 is rendered highly negative a number of times momentarily, thereby momentarily stopping the flow of plate current a corresponding number of times.
  • plate relay 204 falls back and closes atits lower armature a circuit from grounded conductor 226 by way of contacts of relay 210 for the vertical magnet 216.
  • the wipers 222 and 223 are raised step by step until they come to rest opposite the desired level of bank contacts.
  • Slowacting series relay 205 operates upon the first vertical impulse and remains operated throughout the series of impulses. Relay 205 makes a circuit change so as to maintain its own circuit and that of the vertical magnet 216.intact after off-normal springs 218 and 219 have shifted, as they do upon the first vertical step of the switch.
  • relay 205 falls back and transfers the operating circuit through off-normal contacts 219 and its own lower armature and resting contacts to the rotary magnet 217 by way of contacts of the two-ste relay 208.
  • the impulses delivered by plate relay 204 are transmitted to the rotary magnet 217 through olfnormal contacts 219, and contacts of relays 205 and 208.
  • the wipers 222 and 223 are rotated step-bystep over the bank contacts in the selected level until they come to rest upon the set of bankcontacts assigned to the line of substation A2.
  • Relay 207 operates when the first impulse is transmitted to rotary magnet 217. Being slow-acting, relay 207 remains operated throughout the series of impulses.
  • relay 207 operates slowactin relay 209 to prepare a circuit for switc ing relay 210 and to prepare to shift the grid element of the tube 213 into association with wiper 223 to enable the called line to be tested.
  • rela 207 closes a circuit through the upper win ing of the two-step relay 208.
  • the up r winding is relatively ineflicient and is a le, therefore, to operate only the first-step innerlower armature of the relay, thereby closing a locking circuit for relay 208 through both windings in series. This locking circuit is ineffective, however, as long as the initial circuit is established, as the same potential is connected to both terminals of the lower winding.
  • relay 207 When relay 207 falls back at the end of the rotary movement, it opens the circuit of slow-acting relay 209, but relay 209 does opens theinitialcircuit of the u per winding of relay 208, whereupon bot windin s of the relay, ener ize in series, causing t e relay to operate fully. Upon fully operating, relay 208 transfersthe now-open operating circuit at.
  • the operation now to take place depends .upon whether the line of substation A2 is busy or is idle when called. If the line is busy, relay 233 is in an energized condition responsive to an application of positive potential thereto over conductor 232 (if the line is busy as a called line), or over conductor 232 (if the line is busy as a calling line). In this case, the positive potential encountered on conductor 232 or wiper 223 main: tains apositive condition on the grid element of vacuum tube-213 and the plate relay 204 is maintained operated continuously. Under this condition, switching relay 210 is unable to operate. Relayr 208, therefore, re-
  • the busy-tone current applied "to the low er talking conductor from the transformer 254 is transmitted back to the callin line as a characteristic busy tone, informing he subdescribed.
  • Zine idle f 1 Assuming now that the line of substation .A2 is idle when called, plate relay 204 falls back when the'grid element of tube213.is'
  • Relay 210 thereupon operates and closes a locking circuit for itself at its inner-lower armature; extinguishes the filament of the tube 213 at its inner -upper-ar'mature; and at its upper and lower armatures it completes the connections to the conductors 231 and 232.
  • Relay 209 falls back after a short interVal,-responsive to its circuit having beenopenedat t e upper contacts of relay 207.
  • Relay 204 is now deenergized because the filament of the tube 213 has been extinguished at the inner upper contacts of rela 210, but relay 203- remains operated throug its self-locking circuit including the lower contacts of line rela 201.
  • relay 206 closes a locking circuit for, its lower 'windingag it inner lower contacts to'the grounded lockrelay 210, rendering the called line busy to the other connectors and operating cut-ofi' 'ing conductor 226.
  • relay 206 opens the cuit and connects the wipers 222 and 223 to the windings of the back-bridge relay 202, through which talking current is supplied to the called line.
  • the cut-ofi relay 233 of the line circuit LC2 is maintained operated in series with the lower winding of back-bridge relay 202.
  • Back-bridge relay 202 now operates over the called line and shunts the resistance element 211 and 212, thereby increasing the current flow over the calling line so as to better energize the transmitter at the calling substation for conversational purposes.
  • This increase of current flow brought about by cutting out the resistance elements 211 and 213 may be utilized in any-desired manner to effect supervision, which includes operating an individual line meter at the exchange or at the calling substation, or the operation of a supervisory relay in a cord circuit in case the call is coming from an operators switchboard (the switchboard of a calling P. B. X. operator for example).
  • the conversation may now take place between the two substations A1 and A2 as desired, the talking circuit being outlined by the "heavy conductors.
  • the talking conductors are reversed between the windings of the front-bridge line relay 201 and the windings of the back-bridge battery feed relay 202.
  • This reversal of the connections has no efiect upon the flow of direct current, as it is made in a portion of the talking circuit in which direct current does not flow because of the inclusion of the talking condensers between the front and back bridges of the connector.
  • the talking circuit is more nearly balanced against foreign disturbances, as the upperincoming talking conductor of the connector is connected to the lower wiper of the connector and the lower incoming talking conductor of the connector is connected to the upper wiper thereof.
  • the cut-off relay 104 of the calling line and the cut-off relay 223 of the called line are effectively placed on opposite sides of the talking circuit, so that any tendency of one of these relays to unbalance the talking circuit is largely compensated for by the connection of the other relay' on the opposite talking conductor. It is appreciated, of course, that this balance is not, absolutely perfect, even though the two relays may be identical in characteristics, because of the relatively slight resistance in the portion of the talking circuit including theautomatic switches and the condensers in the connector. It is plain, however, that a much greater degree of balance is obtained with the reversal above pointed out at the connector than would be obtained if both cut-off relays were connected to the same continuous talking conductor.
  • back-bridge relay 202 falls back and again inserts the resistance elements 211 and 212 in circuit with the line relay 201, so as to give disconnect supervision when desired.
  • relay 201 opens the circuit of slow-acting relay 203 at its lower armature, and this relay shortly falls back, as it is no longer maintained operated by plate relay 204, because the control of the plate relay 204 has been terminated upon the previously described opening of the filament circuit u on the operation of switching relay 210.
  • 203 falls back, it removes ground potential from lockin conductor 226, permitting the locked up re ays 206 and 210 to restore.
  • lay 203 also closes a circuit through offnormal contacts 221 for release magnet 220.
  • the switch is restored to its normal position, whereupon the release-magnet circuit is opened at off-normal contacts 221.
  • release relay 122 falls back shortly after its circuit is opened at the contacts of plate relay 126. Upon falling back, relay 122 removes ground potential from conductor 132, extinguishing the filament of the tube 114 and permitting the locked-up relays 121, 123,and 124 to fall back. The release ma net 117 0 rates at this time and restores t e line fin er LFl to its normal position, whereupon the releasehen relay the circuit of t magnet circuit is opened at ofl-normal contacts 122.
  • relay 146 is stiflly adjusted, as indicated by label applied in the drawin This characteristic is given to the relay an increased tension of the restorin sprlngs, and it has the effect of delaying t e operation of the relay for a slight interval after e relay is closed.
  • switching relay 146 the o eration of switching relay 146 is prevente when its circuit is closed only momentarily during trunk hunting, in the event that the plate relay 143 is momentarily deenergized during the trunk-hunting time, in case test wiper 158 hap ensto arrive on a bus trunk just as t e impulse springs are bemgopened at the calling devlce to transmit an impulse.
  • test wiper 158 hap ensto arrive on a bus trunk just as t e impulse springs are bemgopened at the calling devlce to transmit an impulse.
  • the stifi adjustment of relay l46 is' useful also in delaying the seizure of a selected trunk long enough to permit the previously established connection to be released in case a trunk happens to be seized (which it very rarely does) just as the receiver is being.
  • balancing coils are employed in the finder and connector, in place of the reversal in the talking conductors of the connector C1 of Fig. 2, to offset the unbalancing tendency of the cut ofl relays of the calling and called lines; standard reverse-battery supervision is em: ployed in Fig; "3 in place'of thehigh-resistancesupervision in the modification of Figs. 1 and 2; and the selector S2 and connector C2 of Fig. 3 has been suitably modified so that the connector is continuously guarded -against seizure by maintaining altered potential on its lower incoming conductor from the time the connector is seized until it is completely restored to normal .conditio n.
  • circuit arrangementsof the modification of Fig. 3 ma be the same as the circuit arrangements of igs. 1 and 2. r v
  • the line circuit L03 of the substation A3 is similar to the line circuit LCl'of the substation Al; the line finder LF2 is similar to the line finder LFl,
  • Fig. 1 except for the addition of the balancing coil 37 1, connected to the upper talking conductor to offset the cut-off relay .(such as 304 of the line of substation A3? ing line; the selector S2 is simi ar to the selector S1 of Fig.
  • the connector C2 is similar to the connector G1 except for the modified guarding circuit involvln armature 380 o elay 303, the associated 0 -normal spring 381 and its contacts, the resistance element 382, the addition of coil 379 and contacts to connect it to the upper talking conductor to balance the cut-off coil of the called line, and the substitution of reversing contacts on the backbridge battery-feed relay 301 instead of the resistance-shunting contacts of the corresponding relay 202, Fig. 2.; and the line circuit L04 is similar to the line circuit LC2 of substation A2.
  • line relay 303 is energized over conductors 301 and 302, whereupon relay 303 grounds .the associated'start conductor'at its lower armature and places theidentifying ground potential upon conductor 305 at its up er armature.
  • a line fin er the line finder LF2
  • the line finder LF2 is started and operates in the manner described in connection with the line finder LFl, Fig. 1, to raise its wipers to the level of bank contacts containin .the calling line and to rotate them over t e bank contacts in this level until the contacts of the calling line are reached.
  • relay 324 corresponding to relay 124, Fig. 1
  • relay 324 operates to extend the line of substation A3 to the selector S2, automatically connecting the retard coil 371 to the upper conductor of the calling line to balance the cut-off relay 304 which is now operated over the lower talking conductor in series with the lower winding of line relay 341 of the selector S to cut oil the line relay 301 and the associated ground connection.
  • line relay .341 energizes over the conductors 328 and 329, closing the li hting circuit for the filament of tube 341, w ereupon plate relay 342 operates, followed by the operation of release relay 342, preparing the selector for operation.
  • plate relay 343 When the first digit in the number is dialled, plate relay 343 responds to close the circuit of verticalmagnet 355 by Way of series relay 345 each time the impulse springs separate at the calling device. The wipers 358 and 359 are thereby raised opposite the desired level of bank contacts. As soon as relay- 345, which is maintained operated throughout the vertical movement, falls back, relay 344 operates through ofl-norma'l contacts 353 and overflow contacts 354, transferring the operating circuit to switching relay 346 and connecting up rotary magnet 356. At its -upper armature, relay 344 transfers the grid element of the vacuum tube 351 from the incoming conductor 358 to the positive line wiper 359 so as to enable the trunk lines in the selected level to "be tested by wiper 359.
  • Each trunk line in use is marked by a ositive potential on the conductor thereof corresponding to conductor 361, with the result that relay 343 is maintained operated until an idle-trunk line is reached, which is marked by a negative potential on the lower conductor thereof.
  • relay 344 maintains the lower winding of line relay 341 connected to incoming conductor 329 at its lower armature, thereby maintaining the cut-off relay 304 of the calling line operated and maintaining a circuit closed over the calling line and over the upper talking conductor for 7 the upper winding of line relay 302 of the connector C2.
  • the associated vacuum tube (not shown) is lighted, whereupon the plate relay operates as explained in connection with the connector C1 and closes a circuit for the release relay 303.
  • Release relay 303 at armature 380 disconnects the incoming conductor 361 from the resistance element 382 and connects it to the lower winding .of line relay 302, by way of contacts of back-bridge relay 301.
  • the two windings of line relay 201 may now remain energized in series over the calling line, and 9 the cut-off relay 304 may now remain energized in series with the lower winding of In the selector S2, relay 344 falls back after a sufficient time interval has elapsed to allow the above-described operation to take place in the connector.
  • the connector C2 operates as described in connection with the connector G1, Fig. 2, to raise its wipers opposite the desired level of bank contacts and rotates them into engagement with the contacts assigned to the line of substation A4.
  • the called line is tested in the hereinbefore described manner and is seized in case it is found to be idle, following which
  • the ring-cut-ofi relay corresponding to relay 206 of the connector C1
  • back-bridge relay 301 operates over'the called line and reverses the in- 139 relay 302, thereby reversing the direction of coining conductors 360 and 361 as regards their connection with the windings of line current-flow over the calling line, as is done now in most standard step-by-step automatic telephone systems, and for the same purpose.
  • cut-off relay 304 is now maintained operated throu h the lower winding of line relay 302, as be ore, but now over the upper talking conductor of the established connection and over the two conductors of the calling line in series.
  • the selector S2 and the line finder LS2 are held operated in the same way as before, because the potential on either of the two talking conductors during conversation is more positive" than the potential of the filament, permitting the plate relays of these switches to remain opera-ted.
  • the release of the connection is efiected when release relay 303 falls back responsive to its circuit being opened by line relay 302, and as explained in connection with rela s 203 and 201 of the connector 01, Fig. 2. en release relay 303 falls back t pe the incoming. conductor 361 winding of line rela 302, but it does not at once connect it to't e negative pole of the exchange battery by way of the resistance element 382, but connects it to ground, hecause'ofi-normal spring 381 is in its operated position.
  • relay 143 falls back and opens the circuit'of release relay 142, at the same time sending an impulse 0 current to vertical magnet 155 and relay 145. This magnet and.
  • relay 142 this relay operate at this time, but the operation is merely incldental and serves no useful purpose.
  • relay 142 /falls back and opens the vertical-magnet circuit at its'lower armature, at the same time closing the release-magnet circuit at the resting contacts of its lower armature, and extinguishing the filament circuit at its upper armature.
  • the cont nuous guarding feature of the conduc 'tor C2, and involving resistance element 382, together with off-normal springs381 and its contacts,' may be applied in the same manner to the conductor C1.
  • the selector. S1 would preferably be replaced by selector S2; the selector S2 tests-over the lower talking conductor in place of the upper talking conductor, and is otherwise especially adapted to operate 'in conjunction with a connector having the guarding feature I above set forth.
  • a vacuum tube having its grid controlled over said line, a plate circuit for said tube including a relay, 'primary :and secondary motor magnets con- 5 trolled by said relay, and means for shifting the control from the primary magnet to the secondary magnet.
  • an automatic switch In combination, an automatic switch, a line extending to said switch, a vacuum tube having its grid controlled over saidline, a plate circuit for said tube including a relay, a primary motor magnet, a circuit controlled by said relay for directively operating said magnet, a secondary motor magnet, and a circuit for automatically operating said secondary magnet also controlled by said relay. 3.
  • an automatic switch a line extending to said switch, a vacuum tube, 'a grid in said tubenormally controlled over said line, primary and secondary operating magnets successively controlled by the late circuit of said tube, and means for shiiiing the control of said grid from the line to a wiper of the switch during the operation ofsaid secondary magnet.
  • an automatic switch a line extending to said switch, a vacuum tube, a grid in said tube controlled by impulses transmitted to said switch over said line, a primary motor magnet controlled by said tube under the control of said grid to select a group of lines accessible to said switch, means effective upon the selection of the group for causing said grid to be controlled over a wiper of said switch, and a secondary magnet controlled by said tube for operating the switch to select an idle line in the selected group.
  • an automatic switch a line extending to said switch, primary and secondary operating magnets for said switch, a vacuum tube for controlling said magnets and means for connecting the grid 0 said tube to said line during the operation of said primary magnet and to a switch wiper during the operation of said secondary magnet.
  • a magnet for causing the switch to hunt for an idle line a vacuum tube, a plate relay controlling said magnet, and a grid connected to a wiper of said switch.
  • a magnet for causing the switch to hunt for an idle line a vacuum tube, a plate relay controlling said magnet. and a grid circuit including lines successively tested by said switch.
  • a magnet for causing the switch to hunt for an idle'line a .vacuum tube, a plate relay controlling said magnet, a id in said vacuum tube controllingsaid pfii te relay, and means for connecting said grid to a talking wiper of said switch during the hunting movement thereof.
  • means for operating said contact maker to make connection with said lines successively means in said automatic switch arranged to be controlled to indicate the busy or idle condition of one of said lines, and means including an electron-discharge device having a control element connected to said contact maker for controlling the last named means.
  • a group of subscribers lines each comprising a pair of talking conductors, a two-wire switchboard multiple for each of said lines, switching devices for extending connections to said lines. and testing apparatus associated with said switching devices including electron-discharge devices for determining the busy or idle condition of a line when connection is to be made thereto.
  • a switching system a group of trunk lines, a hunting switch having access to said trunk lines, means for operating said switch into association with said trunk lines successively, a vacuum tube in said switch having its control element connected to the test wiper of said switch, and means controlled by said vacuum tube in accordance with the busy or idle condition of the tested trunk lines for causing the selector to pass over the busy lines and make connection with the first idle one.
  • a selector switch having access to a plurality of groups of trunk lines, said selector being arranged to respond to directing impulses indicative of a desired group and select such group and to then rotate over the trunk lines of the group. and means including a vacuum tube arranged to control said selector through its plate circuit and having a control element for controlling the current flow in the plate circuit for causing said selector to respond to the directing impulses and for causing said'selector to rotate over the trunk lines in the selected group until an idle trunk line is reached.
  • an'automaticselector switch having access to groups.
  • said selector switch' havingan incoming conductor over which it is controlled and a normally disconnected test wiper through which it makes contact with the terminals of the trunk lines, a wiper-connecting relay for connecting up said wiper to the incoming conductor after the switch has been positioned, primary and secondary operating magnets for operating said switch in its primary and secondary movement, respectively, a vacuum tube having a plate circuit, and means for controlling said primary and secondary operating magnets and said wiper-connecting relay successively through the plate circuit of said vacuum tube.
  • a-switching system a group of lines, an automatic switch arranged to contact with said lines successively, said lines having differing potentials thereon, depending upon whether they are in use or idle, an electronsivelyto regulate the flow of electrons in said device according to whether any trunk line being tested is busy or idle.
  • an electron-discharge device having a control element arranged to influence the electronflow within said device by altering the space charge within the device, and means for connecting said control element to said lines successively to cause the electron emission to be regulated by the respective potentials of the successively engaged lines.
  • an electron-discharge device having a control element arranged-to influence the electronflow within said device by altering the space charge within the device, means for connecting said control element to said lines successively to cause the electron emission to be regulated by the respective potentials on the successively engaged lines, and meanscontrolled by the discharged electrons when a line having a predetermined potential thereon is reached foristopping the testing operation.
  • an electron-discharge device aving a control element arranged to influence the electron-flow within said device by altering the space charge within the device, means 'for connecting said controlelement to said lines successively to cause the electron emission to be regulated by the respective potentials on the successively engaged lines, means con-- trolled by the discharged electrons when a line having a predetermined'potential there-' on is reached for stopping the testing operation, and for seizing such line and altering the potential thereon.
  • an electron-discharge device in a switching system, a group of lines, any one of said lines having a given predeterniined potential thereon in case it 1s idle and a different, predetermined potential thereon in case it is in use, an electron-discharge device, said device having a control element arranged to influence the volume of the discharged electrons by regulating the space charge within the device means ineluding an automatic switch for associating the control element of said electron-discharge device with said lines successively, and means controlled through said electron-dis.- charge path and responsive to the control element of said device being connected to an idle line for stopping the movement of said automatic switch and for causing the idle line to be seized andmarked engaged.
  • an automatic switch having ad'isconnected wiper through which connection is made with a line in any one of a plurality of groups, said switch having a primary movement and a secondary movement, a control conductor incoming to said switch, a vacuum tube having its control element connected to said incoming'control conductor,'a primary ma net controlled through the plate element 0 said vacuum tube under the "control of the control element responsive to impulses received over said control conductor to set the said wiper on a group of lines, means thereupon effective for shifting the plate element of said vacuum-tube from said primary magnet to the secondary magnet to enable the secondary magnet to operate under the control of the vacuum tube to locate said wiper onto -a desired line in the selected group, a wiper-connecting relay, means eflective after the switch has been positioned onan idle line for operating. the wiper-connecting relay under the control of the plate circuit on the vacuum tube, and means for shifting the control element of the vacuum tube to the said disconnected wiper toefiect such operation.
  • a vacuum tube for controlling the switch, a grid in said tube on which different potentials are impressed, a plate circuit for controlling said switch responsive to such potentials, and means for automatically adjusting the filament otential of said tube in order to render sai plate circuit operative.
  • a vacuum tube for'controlling successive operations of said switch, said tube including'an emitting element which is included in the grid and plate circuits, and means responsive to one operation of said switch for altering the potential of said emitting element to prepare the switch to perform the next operation.
  • an automatic switch for extendinga full metallic talking circuit, a vacuum tube, means in the plate circuit of said tube for controlling the operation and holding of said switch and'also the testing function thereof, a grid in said tube connected, to one side of the talking circuit, and means for temporarily shifting the grid connection to the-other side of the talking circuit while said testing is being performed.
  • operating means for selecting a line means includedi a vacuum tube for testing a selected line aiid forcontrolling the r'elease-of the switch, a
  • a vacuum tube means controlled over the plate circuit of said tube for causing the switch to locate a desired line, and means controlled over said plate .circuit thereafter for maintaining said switch in connection with said line.
  • a subscribers line terminating at a telephone exchange, a section of said line in the exchange being normally disconnected from the main portion thereof, a linerelay normally connected to the main portion of said line in the'exchange, said line relay being responsive to a calling condition on said line to place a distinctive potential on one talking conductor of the disconnected section of the line, a line finder having .access to said line and to other similar lines and arranged to search over the disconnected sections of said lines for any calling line, and means in said finder responsive to the said potential placed on a talking conductor of the disconnected section of the line for causing the finder to stop in association with said line and to make connection therewith by way of said disconnected section.
  • a subscribers line terminating at a telephone exchange, a section of said line in the exchange being normally disconnected from the main portion thereof, a line rela normally connected to the main portion of s aid line in the exchange, said line relay being responsive to a calling'condition on said line to place a distinctive potential on one talking conductor of the disconnected section of,the line, a line finder having access to said line and to other similar lines and arranged to search over the disconnected sections of said lines for any calling line, means in said finder responsive to the said potential placed on a talkin conductor of the disconnected section 0 the line for causing the finder to stop in association with said line and to make connection therewith by wayof said disconnected section, a cut-ofl relay connected to the other conductor of said disconnected section, and means for operating said cutofi "relay responsive to the said finder making a finder switch, a grid circuit for 581d testing wiper during the .talking conductors, each line being divided into two sections, each line comprising a
  • a group of telephone lines a finder switch having access to said lines and arranged to be started into operation res onsive to a calling condition on any one 0 said lines to test the lines successively until the calling line is found, means also responsive to the said calling condition for placing a characteristic potential on one of the talking conductors of the calling line characteristic of the calling condition, and means including a vacuum tube in said finder switch controlled over the talking conductors of said lines as they are successively tested for terminating the operation of said finder switch when it reaches the line on which the calling condition exists and for making connection with said line.
  • a finder switch having access to groups oflines and arranged to be started into operation to find a calling line in any group, said finder switch having a group-testing wiper and a line-testing wiper, a vacuum tube in said finder switch arranged to control the hunting operation thereof, and means for connecting the control element of said vacuum tube to the groupou -hunting operation of the finder and or shifting it into engagement with the line-testing wiper durin the line-hunting operation.
  • an automatic two-motion switch having two test wipers controlling. its two motions, respectively, a vacuum tube in said switch arranged for the control of the switch to be exercised therethrough, and means for associating the control element of said vacuum tube with the two test wipers successively.
  • testing apparatus in said switch including a vacuum tube, and means for shiftingtthe plate circuit of said vacuum tube into association with said two control relays, successively.
  • a holding relay for holding the automatic switch in its attained position after the two motions have been executed, and means effective upon the completion of the secondary motion of said automatic switch for bringing said holding relay under control of the plate circuit of said vacuum tube.
  • a group of sub scribers lines a finder having access to said lines, means eflective when one of said lines is calling for operating said finder into association with said lines successively,'a vacuum tube in said finder controlling the operation thereof, means for associating the control element of said vacuum tube with said lines successively as the movement of the finder switch progresses in order to test the lmes, means controlled by said vacuum tube under the control of its control element for terminating the operation of the finder and for seizing the calling line when it IS reached, and means for maintaining the control element of the vacuum tube in connection with the calling line to maintainthe finder SWI-tCh in its operated condition until the receiver is replaced on the callingline.
  • a train of ser ally related automatic switches fonextendmg a talking connection from a calling llne, a vacuum tube in each switch, a circuit including the calling line for supplying potential from the exchange tothe grids of said. tubes, and means in the plate circuit ofv each tube for controlling the release of the associated switch.
  • a train of sanally related automatic switches for extending a full metallic talking circuit from. a calling line, trunk lines extendin between adjacent on y two conductors, a vacuum tube in eac switch, a grid in, each tube connected to the talking circuit, and
  • a group oftrunk' lines each having a-tal ing con uctor normally maintained at a given potential
  • - means for taking any one of said trunk lines for uses (1 for thereupon setting up a current flow ower the said talking conductor thereof and thereby altering the potential on said conductor
  • an automatic switch having access to said trunk lines and having a free hunting movement so that it may effect connection with any idle one of said trunklines
  • a group oftrunk lines means efiective while any one of said trunk lines is in use for placing a characteristic potential on a conductor thereof, an automatic switch arranged to pass over said trunk lines successively and to make connection with the first one thereof not in use, and means in said switch including a vacuum tube having its grid element successively associated with said trunk lines to cause the be continued as long as the characteristic potential is encountered and to cause the first trunk line not having the characteristic potential to be taken for use.
  • lines each havin individual ine eguipment inherently unba ancing the line or conversational, purposes, trunk lines or links through which talking connections may be set up from said lines to other lines, and circuit connections in said links tending to set up an equal and op posite unbalance on said lines, whereby a substantially balanced condition is obtained.
  • an automatic switch having access to lines each of which is maintained at a potential depending upon whether it is in use or not,- an electro-static device in said switch, means effective when a connection is to be set up through one of said lines for associating said electro-static device with said lines successively to locate one not in use, and means controlled by said electro-static device over a talking conductor of a connection set up over one of said lines through said switch for breaking the connection when it is no longer desired.
  • a switch for testing lines for their busy or idle condition means for connecting said switch with said lines successively, and an electro-static testing device in said switch included in the test circuit established with each line.
  • lines each of which is maintained at one potential when idle and at another potential when busy, and means effective when it is desired to take a line for use for electro-staticallytesting said lines successively to determine the condition thereof without drawing current from the lines in use.
  • selective switches means for operating a series of said switches to set up a two conductor metallic talking circuit, means for operating other of said switches in attempting connection with said talking circuit, and testing means in said other switches including vacuum tubes controlled over said talking circuit whereby such attem ted connections are barred without inter ering with conversation on said talking circuit.
  • An automatic telephone system comprising selective switches, in which the usual third conductors extending between switches and the test wipers of the switches are omitted, said system comprising means in each switch, includin a vacuum tube, whereby-the

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
US543759A 1931-06-08 1931-06-08 Telephone system Expired - Lifetime US1903837A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
FR737991D FR737991A (ja) 1931-06-08
US543759A US1903837A (en) 1931-06-08 1931-06-08 Telephone system
DER83678D DE649103C (de) 1931-06-08 1931-12-29 Schaltungsanordnung fuer Fernsprechanlagen mit Waehlerbetrieb

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US543759A US1903837A (en) 1931-06-08 1931-06-08 Telephone system

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US1903837A true US1903837A (en) 1933-04-18

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DE (1) DE649103C (ja)
FR (1) FR737991A (ja)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2419540A (en) * 1943-08-28 1947-04-29 Int Standard Electric Corp Telecommunication switching system
US2428024A (en) * 1945-07-07 1947-09-30 Int Standard Electric Corp Matched potential electrical control system
US2492135A (en) * 1945-07-07 1949-12-27 Int Standard Electric Corp Potential matching electrical control system
US2866004A (en) * 1954-03-04 1958-12-23 Gen Telephone Lab Inc Electronic busy test circuit
US3193621A (en) * 1961-11-01 1965-07-06 Gen Dynamics Corp Telephone line finder
US3210477A (en) * 1962-01-26 1965-10-05 Gen Dynmics Corp Two-way trunk for interconnecting switchboards

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE945569C (de) * 1953-08-25 1956-07-12 Telefonbau & Normalzeit Gmbh Schaltungsanordnung zur vieradrigen Durchschaltung von Vierdrahtleitungen ueber Waehlerstufen

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2419540A (en) * 1943-08-28 1947-04-29 Int Standard Electric Corp Telecommunication switching system
US2428024A (en) * 1945-07-07 1947-09-30 Int Standard Electric Corp Matched potential electrical control system
US2492135A (en) * 1945-07-07 1949-12-27 Int Standard Electric Corp Potential matching electrical control system
US2866004A (en) * 1954-03-04 1958-12-23 Gen Telephone Lab Inc Electronic busy test circuit
US3193621A (en) * 1961-11-01 1965-07-06 Gen Dynamics Corp Telephone line finder
US3210477A (en) * 1962-01-26 1965-10-05 Gen Dynmics Corp Two-way trunk for interconnecting switchboards

Also Published As

Publication number Publication date
DE649103C (de) 1937-08-14
FR737991A (ja) 1932-12-17

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