US2402446A - Telephone system - Google Patents

Description

June 18, 1946.

W. T. POWEL L TELEPHONE SYSTEM Filed Aug. 24, `1944 2 Sheets-Sheet 1 CENTR/7L OFF/CE CODE TABLE 2" STE/7 STAT/0N INVENTOR.

WIA/FRED 7. POWELL ETTORN'Y /2345678 ff/@.rkrn P E v /rRRrrRR y p MrrrrRRRR C Junc 18, 1946. w."r. POWELL TELEPHONE SYSTEM Filed Aug. 24, 1944 2 Sheets-Sheet 2 C011/ TIPOL POINT Patented une 18, 1946 UNITED sTATEs PATENT OFFICE vStromberg-Carlson Company,

a. corporation of. New York.

' i "Application v"'IIhis invention relates 'to telephone systems of v' I' either the manual 0r automatic type.

In the operation of telephone systems it is frequently desirable to provide telephone service to a small group or community of remotely located subscribers. Due to the remoteness of this group from the exchange, it is expensive to extend individual linesto Said subscribers. While 'multi-party lines have .been used in such situations', `multi-party service has real limitations, such as lack of secrecy, and when more than four subscribers are assigned to a given line, the resulting service frequently becomes most vunsatisfactory.

In accordance with the main feature ofthe present invention, there is provided a secret service arrangement whereby a small group or community of subscribers remotely located with respect to the central exchange can be served over a singletel'ephone line.

The' drawings comprising Figs- 1 and 2', when arranged side by side in the order named, dia- 'gramm'atically illustrate a portion of a telephone system incorporating the present invention. Fig. 1, which shows the portion of the system located -at the central oiiice, illustrates in its upper `portion, the finder multiple of a multistation telephone' line, the connector multiple of this line with a sleeve conductor and cut-off relay for each station on the line as well as the code conductors associated with the line; In the lower .left-hand portion of Fig. 1, there is shown a, code table giving the combinations of pulses respectivelyl applied to the tip and ring conductorsof the telephone line to effect the selection of stations thereon. In the lower right-hand portion'oi` Fig. l1, there is illustrated a primary counting relay chain and control relays cyclicallyoperating the relay chain to apply code conditions from the code conductors to the respective tip and ring vconductors of the telephone line. Fig. 2, which shows the portion of the system located at the remote control point, illustrates eight telephone stationsV of the mentioned Vmultistation line, as well as sets ofl line relays and of the stations relays, a line relay and aV stations relay of a'rset being individual to each telephone station. In the lower part of Fig. 2, there is` shown a secondary chain of counting relays'and associated control relays for operating -these counting-relays in step-by-step relation with .the corresponding counting relays. of the primary chain at the central office;

It is believed that the operation of the system will best bra-understoodl by describing the extenlRochester, N.'Y.,

sion of an originating call from one of the sub-l stations of the group or community of subscribers and then by describing the extension of aI call from the remote exchange to one of the-stations of the`group. y Y vLet it beassumed that the subscriber at station #.lremoves his receiver fromvits lswitch-hook to initiate acall. This is effective togenergize a line relay 5 (Fig. 1) and theline relay 6 individual to the calling substation (Fig. 2). This circuit exf tends from a negative pole of battery, winding of the v-line relay 5, back contact and armature la ofthe common cutoffrelay 1, armaturesv, 9 and IIJ 'and back contacts' of the secondary counting relays II, I2 and I3 respectively, con? ductor I 4, upper winding of the relay B, back Contact and armature of the rst stations relay 6a,ring side of the calling line and through the substation, thence over the tip side of thecalling line, armature and back contact of relay 6a, conductors I6 and ILarmatures I9, 20 and 2l and the back contacts of relays I3, I 2 and I I', tip

side 23 of the telephone line extending from the community to the distant exchange, armature 425 and'back contact ofthe common cut-off relay 'l, to the positive side ofbattery. The operation ,of the line relay 5 is effective to cause an idle trunk to be connected to the calling line. v-ln the .present instance, the switching means comprises a finder (notshown) which is controlled .by certain marker-relays (not shown) in -themanner illustrated in thePowell Patent 2,325,877, granted August 3, 1943, to seize the calling line. Theoperation ofthe'lineurelay 6 at the community .is

effective-to interrupt a series circuit'and a step line with its relay 26 (Fig. 2), to be described. This series circuit extends from the negative pole of battery at the remote exchange (Fig. l), conductor 2l, winding of the relay 26, conductor 28, back contacts and lower armatures of the relays 6, 29, 3D and 3l, conductor 32, back contacts and armatures'of ` relays 34, 35, 36, 31,.conductor 39 herein referred to as the step line which extends to the remote oiiice where this circuit will be completed to the positive pole of battery ln the :furthercourse of extending connection. As has ybeen mentioned, the relay 6 at its lower armajductor 39. This is effective to complete a locking 3 circuit for the line relay 6 (Fig. 2), the circuit being completed from the positive pole of battery at the armature 43, conductor 39, armatures and back contacts of relays 31, 36, 35 and 34, conductor 32, armature and back contacts of relays 3|, 36 and 29, armature, front contact and lower Winding o i relay l6, lower winding of station relay 6a, conductor 21 to the negative pole of. battery. When the station relay 6a operates, it extends the calling line over the talking conductors 44 and 45, to the armatures 2| and 8 of the relay Relay is operated from the negative pole of battery, winding of this relay, conductorv46, front contact and armature of relay 6, lback contacts and armatures of relays 29, 30 and 3|, conductor 32, back contacts and armatures of relays 34, 35, 36 and 31, step line conductor 39, armature- 43 and front contact, to ground. With the relay,

thus operated, the talking `conductors 44"'andl 45 of the line are extended through the front contacts and armatures 3 and 2|l to the telephone line including the conductors 23 and 24 which extend to the remote or central oflce'. When the relay 42' (Fig. l) operates over the sleeve conductor 4I, it closes a circuit for the common cut-off relay 1, through the armature 48 and front contact of relay 42, to the positive pole of battery. The common cut-off relay 1 on operating extends the calling line through its armatures 2'5 and la and front contacts, and thence through the armatures and back contacts of either or both relays 50 and 5|, armatures and back contacts of the primary counting relays 52, 53* and 54, and conductors 51 and 58 to the finder multiple. The common cut-ofi relay 1 interrupts the circuits of the cut- oli relays 60, 6|, 6'2, 63, 64, 65, 66 and 61 of the eight numbers used for terminating calls to the eight stations of the community group. At the same time, the relay 1 applies ground potential to the sleeve conductors, such as 68, 69, 10, 1|, 12, 13, 14 and of all these terminals in the connector multiple so that these terminals are rendered busy to incoming calls. Dial tone may be extended to the calling line when the finder extends an idle link circuit to this line. On hearing the dial tone, the calling subscriber may proceed to dial the wanted number of the line terminating at the remote exchange, this portion of the operation of the system being effective in the manner Well-known. It should be understood that the' operation of any line relay, such as 6', 29, 35, 3|, 34, 35, 36 and 31 causes the cir-cuits to function in the manner above described for extending the associated line to the common tip and ring conductors 44 and 45 by operating the associated stations relay, such as 6a, 29a, 30a', 3|a, 34a, 35a, 36a and 31a. These station relays correspond somewhat to cut-ofi' relays since there is one for each subscriber's station serving to disconnect the associated line relay winding. For example, the stations relay `6a of the calling line, under consideration, at its inner upper armature and back contact disconnects its'associated line relay 6 from the line These station relays also function to connect its individual line Whether it s calling or Whether it is being called, through to the common talking line circuit including the conductors 44 and 45 which in turn lead to the central or remote oiice. Further, these station relays are selectively operated in the case of a terminating call to select the wanted station.

At the termination of the connection from the central exchange, ground potential is removed from the sleeve conductor 4| which is effective to release the relay 42. The relay 42 in turn at its armature 48 interrupts the maintaining circuit oi the cut-oli relay 1 which releases. The release of the relay 42 is also effective at its armature 43 to remove positive potential from'the step line including conductor .39. This is effective to release the operated line relay 6 and the operated stations relay 6a, as well' as the secondary counting relay The release of these relays restores the system to its normal condition.

I let it be assumed that a subscribers line, not shown, but located at the central exchange, desires to establish a. telephone connection to the station #1 ofthe group or community. 'I'hat calling subscribers line is extended by usual switching means to the connector tip and ring multiplejl, 18 and the sleeve terminal 68. It should be pointed out that any of the illustrated stations 1 to 8 may be assigned any number desired in the central oflice but it 'is necessary to connect the sleeve conductors of the connector multiple of these numbers to. the sleeve conductors, such as 68 to 15 inclusive at the left of Fig. 1. This means that the tip and ring conductors, such as 11 and 18 of all these numbers are connected together but that individual sleeve conductors are provided for this line. Since the wanted. subscriber is assumed to be at station #1, ground potential Will be applied to the sleeve lconductor 68 of this line, the ground potential being applied through the connector at the central oflice. This ground potential is applied in a circuit through the make-before-break contacts ofthe cut-ofi relay 60, conductor 19, armature and back contact of the cut-ofi relay 1, conductor 80, winding of the cut-01T relay 6U, to the negative poleof battery. Relay 6D on operating closes a locking circuit for itself through its inner armature and front contact and sleeve conductor 68. It will be noted that the common cut-ofi relay 1 at its armatures and back contacts opens up the possible operating circuits of cut-off relays 68 to 61 inclusive. Relay 1 at its front contacts and armatures applies ground potential to the sleeve conductors 69 to 15 inclusive for making these lines busy. The common cut-01T relay 1 at its armature 8l and front contact closes a circuit from positive pole of battery, armature and back contact of the relay 50, winding of relay 82, armature 8| and front contact of cut-off relay 1, back contact and armature 43, step line conductor -39 and thencev through the armatures and back contacts of relays 31, 36, 35 and 34, conductor 32,A armature and back contacts ofrelays 3|, 30, 29' and 6, conductor 28, winding of relay 26, conductor 21, to the negative pole of battery. This circuit is effective to operate the relay 82 at the central olce and the relay 26 at the control point. The relay 82 completes an obvious circuit for the slow to operate relay 84. Likewise, the relay 26 closes an obvious circuit for the slow releasing relay 85. The relay 84 locks itself operated as long as the common cut-orf relay 1 is operated. Relay 84 closes a circuit for operating the relay 55, which circuit is traceable from .the negative poleof battery, Winding of this relay, back contacts and armatures of relays 54, 53 and 52, conductor 86, front contact and armature-of relay 84, to the positive pole of battery. The slow releasing relay 50 is also operated at thisv time from the negative'pole of battery, winding of this relay, back contact 'and armature of relay 52, back contact and armatureof relay 5|, conductor 81, front contact and armature of relay 84, to the positive pole of battery. As soon as the relay 59 operates its armature 88, it opens up the step'line circuit previously described which causes the relays 82 and 26 to release. When the relay 82 releases, the relay 55 is held operated, from the negative pole of battery, Winding of this relay, its inner front contact and armature, conductor 83, back contact and armature of relay 82, oonductor 86, to the positive pole of battery at the front contact and armature of relay 84. Relay 82 also closes a circuit for operating the relay 54 which circuit extends from the negative pole of battery, Winding of relay 54, front contact and armature of relay 55, conductor 89, front pole of battery. When relay 5I operates, it.

opens the energizing circuit ofthe relay 50, previously described. Relay on releasing closes its armature 88 and baci; contact to complete the step line for operating the relays 82 and 25 connected in series therewith. When relay 82 operatesfit effects the release of relay 55. The operation of relay 28 effects the release of the relay 9D which' was operated as soon as'the slow releasing relay 85 Was operated. Likewise,

-relay I3 at the control point was operated by the release of relay 26. The release of relay .effects the release of the relay 5I and relay 5I in turn again completes a circuit for operating the relay 59. Relay 50 opens up the step line including the conductor 39, thereby releasing the relays 82 and 26. The release of the re,- lay 82 causes the operation of the relay 53. Relay 53 locks itself operated through its upper iront contact and armature over conductor 86.

As soon as the relay 53 operates, it closes a circuit for operating the slow releasing relay 5I. This circuit now extends from the negative pole of battery, winding of this relay, armature and back contact of relay 55, armatures and front contact of relays 53 and 54 to the positive pole of battery. When relay 5| operates, it again interrupts the operating circuit of the slow releasing relay 59 and this relay at its armature 88 and back contact again energizes the step line 39 and the relays 82 and 26 in series therewith. When the relay 82 energizes, it effects the release of the relay 54. This relay at its lowermost armature and front contact interrupts the energizing circuit for the relay 5I, which releases. This in turn closes the circuit for again operating the relay 50 which at its armature 88 and back contact interrupts the step line 39. When the step line is interrupted, the relays 82 and 26 are released. This effects the operation of the relay 52 at the central station and the relay II at the remote control point. The circuit of the relay 52 is traceable from th'e negative pole vof battery, winding of relay 52, front contact and armature of relay 53, back contacts and armaturesl of relays 54 and 55, conductor 89,

front contact and armature of relay 84, back contactl and armature of relay 82 to the positive pole of battery. Relay 52, on operating, locks itself operated through its upper front contact and armature, conductor 86, front con- Vthe wanted station.

tactand armature of relay 84, to the positivev pole of battery. The relay II at the remote control-point has its operating circuit completed from the negative pole of battery, Winding of relay II, front contact and armature of relay I2, back contact and armatures of relays I3 and 96, front contact and armature of relay 85, back contact and armature of relay 26, to positive pole of battery. Relay 52 closes a circuit for operating relay 5I. This circuit extends from the negative pole of battery, winding of relay 5|, armature and Vback contact of relay 55, armature and front contact of relay 53, front contact and armature of relay 52, back contact and armature of relay 54 to positive pole of battery. Relay 5I again interrupts the operating circuit of the relay 50 whichl again releases. This again energizes the step line 39 which includes inseries therewith the relays 82 and 26. The operation of the relay 82 opens conductor 86 which has been maintaining the relay 53 operated. Also, Wh'en the relay 26 at the control point 0perates, it effects the release of the relay I2.

When the relay 53 releases, it causes the release,

of the relay 5I but the relay 50 is not energized at this time because its operating circuit .is interrupted due to the fact that the relay 53 has released and the relay 52 is operated.

From the foregoing, it will be understood that the operation of the relays 82, 58 and 5| at the central oice passed through a cycle of operations in which the primary counting relays 55, 54, 53 and 52 operate generally in the manner of the counting rrelay system disclosed in -the mentioned Powell patent. Similarly, at the control point, the relay 26 has a cycle of operations similar to that just described at the central ofce. During the course of this cycle, therelays 90, I3, |2 and II operate in sequence in the order named, also, generally in the manner of the counting relay chain of the patent.

While the cycle of operations just referred to is taking place, station selection to selectr the station #1, is also being eiected. It will be recalled that the relay 85 at the control point was operated at the beginning of the cycle of operations. As soon as the relay 85 operated, it closed `a circuit for operating the conditioning relay 9|,

Aeight station relays will be operated depending on which one of the tip and ring conductors I4 and I'I is grounded at the central office as a result of the operation of the cut-off relay of In the present instance, the station #1 is desired, cut-oil relay 60, therefore, is operated and this relay at its armature 92 and front contact applies positive potential through the back contacts and armatures of relays 54, 53, 52, 5I and'59, conductor 23, arma- ',tures 2|, 20, I9 and back contacts, and thence through the armatures 9m, 9Ic, 9Ic,'9Ig to operate stations relays 6a; 29a, 30a and 3Ia. It will be understood that the four station relays just described will be operated when any one of the nrst four cut-off relays 88 to 83 inclusive at the central station is operated. In like inaninclusive.

ner ifA any one of the last four cut-off relays, namely |54 to 61 inclusive in the centraloflce is operated, the ring conductor 58 is grounded for operating the second half of the station relays at the control point, namely, relays 34a to 31a When the relay 26 is released at the end of the conditioning impulse, the conditioning relay 9| is released and does not operate again during the cycle. It has been mentioned that the rst four station relays were operated by the conditioning impulse. It is now necessary to release all of these operated stations relays except station relay 6a related to the station #1, which relay must be maintained operated for selecting the #l station. Station #l is indicated as the wanted station by the operation of the cut-oir relay S3 at then central station. When the relay 2G, at the control point, releases at the end of the conditioning impulse, a circuit is closed for locking the first four station relays. This circuit is traceable from ground, armature and front contact of relay 85, continuity spring and back contact of relay 26, conductor 93, armature and front contact and lower winding of the relay 3Ia, conductor 21 to grounded battery. Similarly, the relays 39a., 29a and 6a are lock operated in multiple through their armatures, front contacts and lower windings in the same manner as relay 3 I.

At the beginning of the first impulse following the conditioning impulse, during which relay 9| was operated, the relay 26 is again operated and at its continuity spring and back contact it opens the locking circuit just described for the four stations relays. However, a selecting locking circuit is closed for the stations relays 6a, 29a for preventing the release of these relays. This circuit extends from ground on the tip line conductor |58 applied through the front contact and armature of the relay 54, back contacts and armatures of relays 53, 52, and 50, front contact and armature 25, conductor 23, armature 2| and back contact, armature and back contact, armature I9 and front contact, conductor 95, lower armature, front Contact and upper winding of relay 6a, conductor 21 to grounded battery. Also, this ground is extended through the armature 94 and front contact of relay I3, conductor 95, lower armature, front contact and upper winding of relay 29a, conductor 21, to grounded battery. The #l and #2 station relays 6a and 29a are held operated in this circuit but no similar holding circuitI is provided for the stations relays a and 3| a so that these last named relays release. When in the course of the cycle, relay 26 releases at the end of the first impulse period, the locking circuit including the lower windings of relays 6a, and 29a is completed for these relays. At the beginning of the second impulse, the operation of the relay 26 opens the locking circuit including the lower windings of relays 6a and 29a. The #2 station relay 29a releases because no circuit is completed at this time for its upper winding since the relay I3, which previously completed the circuit for relay 29a at the armature 94 and front contact, is released. However, relay I2 is now operated and at its armature 20 completes a circuit for maintaining the #l stations relay 6a operated during the second impulse period. This circuit extends from the positive pole of battery, armature 91 of the cut-off relay 60, conductor 98, front contact and armature of relay 53 now operated, back contact and armatures of relays 52, 5I and 50, .tip conductor 23, armature 2l and back contact of relay II, armature 20 and front contact of relay I2, conductor 95, lower armature and front contact and upper Winding of relay 6a, conductor 21 to the negative pole of battery. The potential applied at the armature 91 of cut-01T relay 60 is ineffective to affect the #3 stations relay 30a and the #7 stations relay 36a, both of which are released at this time.

When the relay 26 is released at the end of the second impulse period, a locking circuit is completed for the #l stations relay 6a from ground at the armature and front contact of relay 85, continuity spring and back contact of relay 26, thence over conductor 93, lower armature, front contact and lower winding of relay 6a, conductor 21 to grounded battery. Also, when the relay 26 is operated at the beginning of the last impulse to continuously energize the step line 3S, the #l stations relay 6a is maintained energized from grounded battery, conductor 21, lower winding of relay 6a, its front contact and armature, conductor 93, front contact and armature of relay II, armature and continuity spring of relay 26, front contact and armature of relay to ground. As a result of the cycle of operations, including the transmission of impulses over the step line in the manner just described, the relay Ba is selected and maintained operated. Relay 6a at its upper armatures and front contacts extends the tip and ring conductors of the calling line to the conductors 44 and 45 and thence through front contacts and armatures I8 and 2| of relay conductors 24 and 23, armatures and front contacts of the common cut-off relay 1, armatures and back contacts of relays 59 and 5|, armatures and front contacts of relays 52, tip and ring conductors 11 and 18 which terminate in the connector switch. On the seizure of the called line, ringing current is applied to the called line to actuate the straight line ringer provided thereafter,

It is believed unnecessary to explain the operation in detail for selecting any one of the eight other lines illustrated. lt will be sulcient to point out that the cut-off relay of each line applies ground in various combinations to conductors which are associated with the tip and ring side of the line during the various steps in the cycle. By referring to the code table shown in the lower left-hand corner of Fig. l, it will be seen how in the case of the rst station, ground is applied to the tip conductor during the conditioning period, ground is also applied over the tip conductor during the rst and second steps to select station #1. However, in order to select station #2, ground is applied t'o the tip conductor during the conditioning step and during the rst step. However, during the second step ground is applied to the ring conductor to select the #2 station. These various combinations, as indicated by the code table, and which are determined by the operation of the cut-01T relay of the called line, selectively operate the stations relay of the called line to eiect the selection. v

The release of the connection at the central cnice removes ground from the sleeve conductor E8 to eiect the release of the cut-oil relay 50 individual to the station and the common cut-off relay 1. The release of the relay .1 at its armature 8i opens up the step line 39 to effect the release o1 relays 82 and 25. These last named relays cause the release of the slow releasing relays S and 85. These relays in turn eiect the release of relays and l l so that the equipment is in its normal condition.

What I claim is:

l. In a telephonev system, a telephone exchange, a pluralityof telephone lines terminating at said exchange, one` of said telephone lines extending to a remote control point and having a plurality of stations thereon at said point, means for interconnecting said telephone lines, a plurality of sleeve conductors at said exchange, one sleeve conductor being provided for each station associated with said multi-station line, a group of selectively operable relays at the remote point efiective to connect a wanted station to said multistation line to the exclusion of other stations thereon, and means responsive to the seizure of the sleeve circuit individual to a wanted station onsaid line for selectively operating said relays to connect the wanted station telephonically to said multi-stationline. Y

.2. Ina telephone system, a telephone exchange, a-plurality of telephone lines terminating at said exchange, a multi-station telephone line terminating in a plurality of outlets at the exchange and extending `to a remote control point where it is provided witha station corresponding to each outlet, means for interconnecting said telephone.

lines, a group of selectively operable relays at the remote,point.eiectivetolconnect a wanted substation to said multi-station line to the exclusion of other stations thereon, and means responsive to the extension of a telephone line to a selected outlet of the multi-station line for selectively operating said relays to connect telephonically to said multi-station line, the station thereon corresponding to said selected outlet, to the exclusion of other stations thereon.

3. In a telephone system, a telephone exchange, a plurality of telephone lines terminating at said exchange, a multi-station telephone line terminating at the exchange and extending to a remote control point where it is provided with a plurality of stations, said multi-station telephone line between said exchange and said control point comprising only two talking conductors and a control conductor, a plurality 4of sleeve conductors local to the exchange, one sleeve conductor for each station associated with said multi-station line, means for interconnecting said telephone lines, a group of relays at the remote point selectively operable in response to various series of code signais and eiective to connect a wanted substation telephonically to said multi-station line to the exclusion of other stations thereon, means responsive to the seizure of the sleeve circuit individual to a wanted station on said line for predetermining a series of code impulses distinctive of said last-mentioned station, and means governed'over said control conductor for effecting the transmission over said talking conductors to said relays of said predetermined series of code impulses.

4. In a telephone system, a telephone exchange, a plurality of telephone lines terminating at said exchange, a multi-station telephone line terminating at the exchange and extending to a remote control point Where it is provided with a plurality of stations, a plurality of sleeve conductors at said exchange, one sleeve conductor being provided for each station associated with said multi-station line, means for interconnecting said telephone lines. a group of selectively operable relays at the remote control point, code conductors also associated with the multi-station line at the exchange, means responsive to the seizure of the sleeve conductor of a wanted station on the multistation line for establishing a code condition on certain of said codeconductors distinctive of said wanted station, and means responsive to the established code condition for selectively operating Asaidrelays to lconnect the wanted station telephonically to said multi-station line to the exclusion .of other stations thereon.

5.` In a telephone system, a telephone exchange, a plurality of telephone lines terminating at said exchange, amulti-station telephone line terminating at the exchange and extending to a remote control point where it is provided with a plurality of stations, a plurality of sleeve con-V ductors and cut-01T relays at said exchange, one sleeve vconductor and a cut-orfrelay electrically connected thereto for each 'station associated with said multi-station line, lmeans for interconnectingsaid telephone lines, a group of selectively operable relays at the remote point, code conductors also associated with the multi-station line, means responsive to the seizure of the sleeve conductor and the operation of its connected cuto relay individual to they wanted station for establishing a code condition on said code conductors `distinctive of said Wanted station, and meansV responsive to the established code condition forselectively operating said relays to connectl the-wantedl station telephonically to said multi-station line to the exclusion of other stations thereon.

6. In a telephone system, a telephone exchange, a plurality of telephone lines terminating at said exchange, 'a multi-station telephone line terminating at the exchange and extending to a remote control point Where it is provided with a plurality of stations, a plurality of sleeve conductors and cut-oil relays at said exchange,` one sleeve conductor and a cut-off relay electrically connected thereto for each station associated with said multi-station line, means for interconnecting said telephone lines, a group of selectively operable relays at theremote point, code conductors also associated with the multi-station line, means responsive to the seizure of the sleeve conductor and the operation of its connected cutoff relay individual to the wanted station for establishing a code condition on said code conductors distinctive of said wanted station, means responsive to the seizure of the sleeve conductor and the operation of its connected cut-oil relay individual to the wanted station for establishing code conditions on said code conductors distinctive of said wanted station, a sender set into operation by the seizure of any one of said sleeve conductors, said sender operating to transmit said code conditions to the control point, and means responsive to the transmitted code conditions for selectively operating said relays to connect the wanted station telephonically to said multi-station' line to the exclusion of other stations thereon.

7. In a telephone system, a telephone exchange, a plurality of telephone lines terminating at said exchange, a multi-station telephone line terminating at the exchange in a plurality of outlets and extending to a remote control point where it is provided with a station individual to each outlet, a plurality of sleeve conductors and cutoi relays at said exchange, one sleeve conductor and a cut-oir relay electricallyconnected thereto associated with each outlet, a group of selectively operable relays at the remote point, code conductors also associated with the multi-station line at the exchange, means responsive to the seizure of the sleeve conductorand the oper-v ation of its connected cut-01T relay individual to the Wanted station for establishing code conditions on said code conductors distinctive of said wanted station, a sender started into operation by theseizure of any one of said sleeve conductors, said sender including a chain of primary counting relays operating in sequence to transmit said code conditions to the control point, and means including a secondary chain of countingfrelays operating in step-by-step relation with said primary chain of counting relays, said secondary chain of counting relays operating to apply the transmitted code conditions for selectively operating said relays to connect the wanted station telephonically t said multi-station line to the exclusion of other stations thereon.

8; Ina telephone system, a telephone exchange, a'iplurality of telephone lines terminating at said exchange, a multi-station telephone line terminating at lthe exchange in al plurality of outlets and extending to `a remote control point where it is provided with a station individual to each outlet, a plurality of sleeve conductors and cut-off relays at said exchange, one sleeve conductor and a cut-off relay electrically connected thereto associated with each outlet, code conductorsV also `associated with the multi-station line at the exchange, a common line relay at the ex-A change for all of said stations, a line" relay and a station relay for each station on said multi-station line, each station relay when operated serving to connect its station telephonically to the multi-station line, means responsive to the initiation of a call from any of said stations for operating its line relay and said common line relay, means responsive to the operation of the common line relay for extending the multi-station line in the direction of a wanted telephone, means responsive to the extension of the multistation line for completing a. locking circuit for the operated line relay, said locking circuit being serially completed at all of the other line relays, said locking circuit being also effective to operate the station relay of the calling station, means responsive to the seizure of the sleeve conductor individual to a wanted station of the multi-station line on the extension of a telephone line thereto for operating the cut-oi relay of the wanted station, said operated cut-oil' relay operating to apply to' said code conductors code conditions distinctive of said wanted station, means responsive to said code conditions for selectively controlling the station relays to operate the station relay of the Wanted station to the exclusion of the other station relays.

WINFRED T. POWELL.

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