US2126875A - Selection controlling apparatus for telephone systems - Google Patents

Description

r. DIMOND 2,126,875 SELECTION CONTROLLING APPARATUS FOR TELEPHONE SYSTEMS Aug. 16, 1938.

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SELECTION CONTROLLING APPARATUS FOR TELEPHONE SYSTEMS Filed Nov. 26, 1937 3 Sheets-Sheet 2 //v l/ENTOR 7. L. D/MOND A TTORNEV Aug. 16, 1938. T, DlMOND 2,126,875

SELECTION CONTROLLING APPARATUS FOR TELEPHONE SYSTEMS Filed Nov. 26, 1937 v 5 Sheets-Sheet 3 w l EN TOR 77L. D/MOND A TTOR/VEV Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE SELECTION CONTROLLING APPARATUS FOR TELEPHONE SYSTEMS Application November 26, 1937, Serial No. 176,557

11 Claims.

This invention relates to telephone exchange systems and more particularly to a sender for controlling the setting of selector switches in accordance with digit registrations.

Heretofore senders for controlling the setting of selector switches have been provided with register switches of the step-by-step type or groups of register relays for registering the digits of wanted line designations which are successively ,m set by series of digit impulses dialed by a calling subscriber or by series of code impulses keyed by an operator. The present invention relates to a sender of this general type in which groups of gas-filled tubes are employed as registers in lieu in of groups of relays whereby the cost of the sender is reduced, the circuits of the sender are simplified and the registration response is rendered more sensitive and faster.

In accordance with the present invention a group of cold cathode tubes is employed to register each digit of a line designation, there being a group of tubes for each digit to be registered.

For convenience of illustration, the invention has been disclosed in connection with a key pulsing sender of the type disclosed in Patent 1,916,760 granted July 4, 1933 to I. H. Henry, for enabling an operator to complete connections to subscribers lines terminating in an oflice equipped with selector switches of the step-bystep type. The invention is not, however, to be considered as limited to senders of the key pulsing type or to the control of step-by-step switches, but could with slight modification be made applicable to receive digit series dialed directly by sub- 35 scribers, or to receive series of code impulses transmitted thereto from another sender and to control the setting of any known type of selector switches such as the switches used in the wellknown panel type or cross-bar type systems.

The groups of tubes are associated in succession by steering-in relays with impulse recording relays which are responsive to the series of impulses incoming to the sender. Each group of tubes comprises four two-element cold cathode F. gas-filled tubes, the cathode of each tube having a positive potential connected thereto upon the seizure of the sender, the control cathode or control electrode of each tube being connected through a high resistance to ground and the midso point of the resistances being connected to the front contacts of the steering-in relay associated with the group of tubes. While tubes of the cold cathode type have been disclosed, it will be apparent to those skilled in the art that tubes of the hot cathode type could equally well be used.

When the control electrodes of a group of tubes have been connected over contacts of the associated steering-in relay with the recording conductors extending to the contacts of the impulse recording relays, the tubes may be rendered conducting singly or in combination by the application of negative potential of the value required by the connection of such potential to the recording conductors through the selective operation of the recording relays in response to an impulse code incoming to the sender, in the present instance, by the keying of a digit by the operator.

In response to successive impulse codes, the steering-in relays are operated in the usual manner to associate successive groups of tubes with the recording conductors so that successively keyed or dialed digits of a line number may be successively registered by the groups of tubes.

For controlling the transmission of series. of outgoing impulses for setting selector switches in accordance with the registrations set up in the groups of registering tubes, a group of threeelement cold cathode gas-filled decoding tubes is provided. It is to be understood, however, that the decoding tubes might be of the hot cathode type. Each of the decoding tubes is provided with an anode, a cathode and a control cathode or control electrode. The anode of each of these tubes is connectible through the winding of a decoder register relay to a source of positive potential and the cathode of each tube is connected to a source of negative potential. The control electrode of each of these tubes is connected to a bus-bar. The bus-bars to which the control electrodes of these tubes are connected may be connected successively to the control electrodes of the several groups of register tubes by a chain of steering-out relays.

The groups of decoder register relays are employed to control out pulsing in the usual manner, being set by the decoder tubes successively from the register tubes to control out pulsing in accordance with the registrations set up in the groups of register tubes.

If, for example, it be assumed that the first group of register tubes has been set to register the digit 1 by rendering only the first tube of the group conducting and that the second group of register tubes has been set to register the digit 3 by rendering only the first and second tubes of the second group conducting, when now the decoder tubes are connected to the first group of register tubes by the operation of the first of the chain of steering-out relays, only the first decoder tube will fire or become conducting since it will be the only one of the decoder tubes which will have positive potential of a sufiicient'value applied to its control electrode through a conducting register tube, that is, the first register tube. The first decoder tube upon firing will operate the associated decoder register relay to control out pulsing for the first registered digit 1.

As soon as out pulsing is completed for the first registered digit, the first steering-out relay is released, the conducting decoder tube and operated decoder register relay are restored and the second steering-out relay is operated to associate the decoder tubes with the second group of register tubes upon which the second digit has been registered. With the assumption that the first two tubes of the second group of register tubes have been rendered conducting to register the digit 3, the first two decoder tubes will fire to operate the first two decoder register relays since they will be the only decoder tubes which will have positive potential of a sufiicient value applied to their control electrodes through the first and second conducting register tubes of the second group of register tubes. The reoperation of the decoder register relays will now control out pulsing for the second registered digit. Other digits of any required number may be registered and out pulsing controlled in accordance therewith in the same manner. To simplify the disclosure it will be assumed that it will be necessary to register line designations having a maximum of four digits.

Having given a general description of the invention and the mode of its operation, it is believed that a better understanding thereof may be had from the following detailed description taken in connection with the accompanying drawings in which:

Fig. 1 shows recording relays for receiving incoming series of impulses transmitted in accordance with the digital values of the digits of line designations, out pulsing and counting relays for controlling the setting of selector switches and other control relays;

Fig. 2 shows the decoder tubes and associated decoder register relays, two groups of register tubes and associated steering-in and steering-out relays;

Fig. 3 shows other groups of register tubes and associated steering-in and steering-out relays; and

Fig. 4 is a diagram showing how Figs. 1, 2 and 3 should be arranged to fully disclose the invention.

Referring now to the drawings only such parts of a sender of the key pulsing type disclosed in the aforementioned patent to Henry have been illustrated as are considered necessary to a full disclosure of the present invention.

It will be assumed that an operator, desiring to complete a connection with a line terminating in a step-by-step ofiice whose directory number is 1379, plugs into the jack of a trunk (not shown) extending toward the office in which the desired line terminates. It will be further assumed that the sender disclosed is idle and thereupon becomes associated with the trunk circuit through a link circuit in the manner fully described and disclosed in the Henry patent. Upon the seizure of the sender ground is applied to conductor I whereupon relay IOI operates in a circuit through its left and middle windings, right normal contacts of relay I02 to ground at the back contact of relay I03 and in operating establishes an obvious circuit for relay I04. Relay I04 upon operating connects ground to conductors E05, I06 and I01. Upon the connection of ground to conductor I05 an obvious operating circuit is established for relay I08 and upon the connection of ground to conductor I06, a circuit is established therefrom over the outer right back contact of relay I 09, conductor IIO, winding of steering-in relay 204, winding of transfer relay 203, conductor 200 to battery and ground.

Relays 203 and 204 operate and lock in a circuit from battery through their windings in series, the outer upper front contact of relay 203, the upper back contact of steering-inrelay 224, conductor I, the upper back contact of relay 344 to ground on conductor I00 and a circuit is established from ground on conductor I I0 over the inner upper front contacts of relay 203, conductor III and the right normal contacts and winding of relay I09 to battery and ground. Relay I09 thereupon operates, looks over its right alternate contacts to ground on conductor I06 and opens the initial operating circuit of relays 203 and 204. At its outer left contact, relay I09 connects the source II2 of 90-volt positive potential to conductor H3 and thence to the lower cathodes of each of the register tubes 205, 206, etc.

Upon the seizure of the sender impulsing circuits are also established from the tip conductor II4 over the inner upper back contact of relay 344, conductor II5, thence in series through the windings of polarized recording relay II6, marginal recording relay II? and sensitive recording relay I I8 to 24-volt battery and ground, and from ring conductor II9 over the lower back contact of relay 344, conductor I20, thence in series through the windings of polarized recording relay I26, marginal recording relay I21 and sensitive recording relay I 28 to 24-volt battery and ground.

It has been assumed that the first digit of the designation of the desired line is 1. When, therefore, the operator keys this digit, ground through a low resistance is applied to impulse conductor II4 whereupon sufficient current fiows through the windings of relays H6, H1 and H8 to cause the operation of both the marginal relay II! and the sensitive relay H8, but polarized relay IIB does not receive current in the proper direction through its winding to cause its operation. With transfer relay 203 operated, the operation of relay II 8 establishes a circuit from ground over its contact, conductor I2I, inner lower front contact of relay 203, winding of transfer relay 223 to battery and ground over conductor 200. Relay 223 thereupon operates and looks through the winding of steering-in relay 225, upper front contact of relay 223, conductor 2I9, upper back contact of steering-in relay 304, conductor 20I, upper back contact of steering-in relay 344 to ground on conductor I06, but steering-in relay 224 being shunted so long as relay II8 remains operated, does not operate at this time. Recording relay II'I upon operating closes a circuit extending from the negative terminal of the 45- volt grounded battery I22, over conductor I23,

the inner lower front contact of steering-in relay 204 through resistance 2I5 to ground and through resistance 2II to the upper or control electrode of tube 205 of the first digit register. With 90- volt positive potential applied to the lower cathode and 45-volt negative potential applied to the upper cathode of tube 205, this tube ionizes and becomes conducting, the ionization of the tube continuing after the subsequent release of relay II! in a circuit from the source of 90-volt positive potential II2 applied to its lower cathode, through the tube to the upper cathode and thence to ground through resistances 2H and 2I5 in series.

When the operator releases the digit key at her key-set, recording relays H1 and H8 release, relay H8 upon releasing removing the shunt from around the winding of steering-in relay 224 whereupon relay 224 operates in the locking circuit of relay 223, opening at its back contact the locking circuit of transfer relay 203 and steering-in relay 204, causing these relays to release. Relay 224 upon operating connects the recording conductors extending from the contacts of recording relays H1, H6, I26 and I21 to the control electrodes of the tubes 225 to 228, respectively, and relay 284 upon releasing disconnects the recording conductors from the control electrodes of the tubes 205 to 208, inclusive.

When the operator depresses the key of her key-set to register the second digit 3, 48-volt battery is connected through a low resistance to conductor H4 and a circuit is established as traced through the windings of recording relays H6, H1 and H8 in series to the 24-volt battery and ground. The direction of current flowing through the windings of these relays is such as to operate the polarized relay H6 and since a low resistance has been included in the circuit, relays H1 and H8 also operate. Relay H3 upon operating with transfer relay 253 released and transfer relay 223 operated, completes a circuit from ground over the front contact of relay H8, conductor I2I, inner lower back contact of relay 203, inner lowerfront contact of relay223, conductor220, winding of transfer relay 303 to battery on conductor 200. Relay 303 operates and locks in a circuit from battery through its winding and the winding of steering-in relay 304, upper front contact of relay 303, upper back contact of steering-in relay 324, upper back contact of relay 344 to ground on conductor I06, but relay 334 being shunted so long as relay H8 remains operated, does not operate at this time. Recording relay H1 upon operating closes a circuit extending from the negative terminal of the 45-volt battery I22, over conductor I23, the inner lower front contact of steering-in relay 224, through resistance 235 to ground and through resistance 23! to the upper or control electrode of tube 22-5 of the second digit register. Recording relay H8 upon operating closes a circuit extending from the negative terminal of the 45-volt battery I22, over conductor I24, the lower front contact of relay 224 through resistance 236 to ground and through resistance 232 to the upper or control electrode of tube 226 of the second digit register. Since tubes 225 and 226 have -volt positive potential connected to their lower cathodes, they both ionize and become conducting and remain conducting after the subsequent release of recording relays H6 and H1.

When the operator releases the depressed key, recording relays H6, H1 and H8 release, relay I I8 upon releasing opening the shunt around the Winding of steering-in relay 304 whereupon relay 304 operates in the locking circuit of relay 803, opening at its back contact the locking circuit of transfer relay 223 and steering-in relay 224 causing these relays to release. Relay 304 upon operating connects the recording conductors extending from the contacts of recording relays H1, H6, I26 and I21 to the control electrodes of the tubes 385 to 308, respectively, and relay 224 upon releasing disconnects the recording conductors from the control electrodes of the tubes 225 to 228, inclusive.

In response to the operation of a'key of the operators key-set to register the third digit 7, 48-volt battery is connected through a high resistance to conductor H4 with the result that current flows through the windings of relays H6, H1 and H8 in such a direction as to cause the energization of polarized relay H6 andsince a high resistance has been included in the impulsing circuit, marginal relay H1 does not operate, but sensitive relay H8 does operate. The operated key also connects ground through a low resistance to conductor H9 thereby completing a circuit as traced through the windings of recording relays I26, I21 and I28 to 24-volt battery and ground. The direction of current flowing over this circuit is not such as will operate the polarized relay I26, but due to the inclusion of a low resistance, both marginal relay I21 and sensitive relay I28 operate.

The operation of relays H8 and I28 connects ground to conductor I2I thereby completing a circuit over the inner lower back contacts of transfer relays 203 and 223, conductor 22I, inner lower front contact of transfer relay 383, winding of transfer relay 323 to battery on conductor 200. Relay 323 operates and locks in a circuit from battery through its winding and the winding of steering-in relay 324, upper front contact of relay 323, upper back contact of relay 344 to ground on conductor I06, but relay 324 being shunted so long as relays H8 and I28 remain operated, does not operate at this time. The operation of polarized recording relay H6 closes a circuit from the negative terminal of 45-volt battery I22, over conductor I24, the lower front contact of steering-in relay 304, through resistance 3I6 to ground and through resistance 3I2 to the upper or control electrode of tube 308 of the third digit register. Recording relay I21 upon operating closes a' circuit from the negative terminal l of- 45-volt battery I22, over conductor I25, the outer upper front contact of steering-in relay 304, through resistance 3 I 8 to ground and through resistance 3I4 to the upper or control electrode of tube 308 of the third digit register. 306 and 308 have 90-volt positive potential connected to their lower cathodes they both ionize and become conducting and remain conducting after the subsequent release of recording relays H6 and I21.

When the operator releases the digit key, recording relays H6, H8, I21 and I28 release, relays H8 and I28 upon releasing opening the shunt around the winding of steering-in relay 324 whereupon relay 324 operates in the locking circuit of relay 323, opening at its back contact the locking circuit of transfer relay 303 and steeringin relay 304, causing these relays to release. Relay 324 upon operating connects the recording conductors extending from the contacts of recording relays H1, H6, I28 and I21 to the control electrodes of the tubes 325 to 328, respectively, and relay 304 upon releasing disconnects the recording conductors from the control electrodes of the tubes 305 to 308, inclusive.

In response to the operation of a key of the operator's key-set to register the last digit 9, 48- volt battery through a low resistance is connected to conductor H9 with the result that current flows through the windings of recording relays I26, I21 and I28 in such a direction as to cause the energization of polarized relay I28 and since a low resistance has been included in the impulsing circuit, both the marginal relay I21 and the sensitive relay I28 also operate. The oper- Since tubes ated key also connects ground through a high resistance to conductor I I4 thereby completing a circuit, as traced, through the windings of recording relays H6, H1 and M8 to 24-volt battery and ground. The direction of. current flowing over this circuit is not such as will operate the polarized relay H6 and due to the inclusion of a high resistance, marginal relay I I 7 does not operate, but sensitive relay IIB does operate.

The operation of relays Ii 8 and I28 connects ground to conductor I2I thereby completing a circuit over the inner lower back contacts of transfer relays 203 and 223, conductor 22I, inner lower back contact of transfer relay 333, inner lower front contact of transfer relay 323 to battery through the winding of transfer relay 343. Relay 343 operates and locks in a circuit from battery through its winding and the winding of relay 344, upper front contact of relay 343 to ground on conductor I05, but relay 344 being shunted so long as relays H8 and I22 remain operated, does not operate at this time. The operation of polarized recording relay I 25 closes a circuit from the negative terminal of 45-volt battery I22, over conductor I29, the inner upper front contact of steering-in relay 324,through resistance 33! to ground and through resistance 333 to the upper or control electrode of tube 32? of the fourth digit register. Recording relay I2? upon operating closes a circuit from the negative terminal of 45-volt battery I22, over conductor I25, the outer upper front contact of steering-in relay 324, through resistance 338 to ground and through resistance 334 to the upper or control electrode of tube 328 of the fourth digit register. Since tubes 3 2T and 328 have 90-volt positive potential connected to their lower cathodes, they both ionize and become conducting and remain conducting after the subsequent release of recording relays I25 and I2l.

When the operator releases the digit key, recording relays H8, I25, I27 and I28 release, relays I I8 and I28 upon releasing opening the shunt around the winding of relay 344 whereupon relay 344 operates in the locking circuit of transfer relay 343 opening at its upper back contact the locking circuit of transfer relay 323 and steering-in relay 324 causing these relays to release. Relay 324 upon releasing disconnects the recording conductors extending from the contacts of recording relays H5, H7, I23 and I2'I to the con trol electrodes of tubes 325 to 323, inclusive. Relay 344 upon operating also at its inner upper and inner lower back contacts disconnects the impulsing conductors I i4 and I I9 from the windings of the recording relays H5, H1, I18, I20, I27 and I28 and connects these conductors over its .inner upper and inner lower front contacts to 48-volt battery through the upper windings of relays 345 and 346, respectively. The circuit from impulsing conductor I I4 may now be traced over the inner upper front contact of relay 344, upper back contacts of relays 34? and 348, through the upper winding of relay 345 to battery and the circuit from conductor I I9 may be traced over the lower front contact of relay 344, lower back contacts of relays 34'I and 348, through the upper winding of relay 340 to battery.

At the key-set two polarized relays whose windings are connected at this time to the impulsing conductors I I4 and H9 operate as described fully in the Henry patent, but relays 345 and 346 being marginally wound do not operate. Upon the operation of both polarized relays at the key-set, direct ground is connected to impulsing conductor I l 4 whereupon relay 345 operates locking in a circuit from battery through the winding of relay 348, the lower winding and front contact of relay 345 to ground on conductor I06. Relay 348 operates in this locking circuit, opening at its back contacts the operating circuits previously traced through the upper windings of relays 345 and 345 and at its front contacts connects 24-volt battery through resistances 349 and 350 over the back contacts of relay 347 and the front contacts of relay 344 to the impulsing conductors I I4 and H9. The operators key-set circuit is now released in the manner described in the Henry patent.

It will be recalled that upon the seizure of the sender relay I08 operated. Upon operating it establishes an operating circuit for the polarized impulse generating relays I32 and I 33 extending from ground over its right front contact conductor I53, through resistances I35 and I35 and thence in parallel through resistance I37 and over the lower normal contacts of jack I38, left windings of relays I32 and I33, upper normal contacts of jack I38 and resistance I39 to battery, and relays I32 and I33 both operate. At this time the out-pulsing loop is established from conductor I30, left front contacts of relay I08, outer left back contact of relay I 92, back contacts of relay I34 and front contacts of relay I32 in parallel, until relay I34 operates at the end of the synchronizing impulse as will be later described, to conductor I3I. Relay I08 also at its outer left contacts switches the condenser I40 and resistance I4I across the impulsing conductors I30 and I3I. At this time condenser I42 associated with the impulse generating relays I32 and I 33 is also charged in a circuit extending from ground through condenser 542, the upper normal contacts of jack I43, through the right windings of relays I32 and I33, the lower normal contacts of jack I43, resistance I 39 to battery and ground.

As soon as the first digit keyed by the operator has been registered in the first group of register tubes and transfer relay 203 has released, with relay I99 operated, a circuit is established for relay 203, conductor 240, inner left front contact of relay I09 to ground at the outer left back contact of counting relay I46. Relay 209 upon operating looks through its winding and the upper winding of relay 2I0, inner lower front contact of relay 209, conductor 24I, right back contact of counting relay I52 to ground on conductor I01, but relay 2I0 being shunted does not operate at this time. Relay 209 also connects the upper or control electrodes of the tubes 295 to 208, inclusive, of the first tube register, over its four upper front contacts through resistances 249 to 252, inclusive, to the right or control electrodes of the decoder tubes 245 to 248, respectively. At its lowermost front contact relay 209 connects 90-volt positive potential applied from battery M2 to conductor II3, thence over conductor 242 and through the windings of decoder register relays 255 to 258, inclusive, in parallel to the anodes of decoder tubes 245 to 248, inclusive, and establishes a circuit from ground over the right front contact of relay I08, conductor I63, middle lower front contacts of relay 209, conductor I64, inner left back contact of relay I02, front contact of relay I33, upper contacts of jack I38, left windings of relays I32 and I33,

lower contacts of jack I38 to battery through resistance I31 and in parallel with the left windings of relays I32 and I33 to battery through resistance I39. When ground is applied to conductor I64, the left windings of relays I32 and I33 become shunted, but relays I32 and I33 do not release immediately because the discharge current from condenser I42, which was normally charged, now flows in a circuit previously traced therefrom through the right windings of relays I 32 and I33, over the front contact of relay I33 to ground on conductor I63 and holds the relays operated. When the discharge current from condenser I42 decays to a certain point the left windings of relays I32 and I33 become controlling and the relays I32 and I33 both release.

When relay I33 releases, the ground is removed from its front contact and current now flows through the left windings of relays I32 and I33, thus tending to operate the relays. They do not operate immediately, however, because the charging current for condenser I42 now flowing through the right windings of these relays prevents them from doing so until after the charging current has decayed to a sufficiently low value. This pulsing action continues until ground is removed from the armature of relay I33 by the release of steering-out relay 209 following the transmission of impulses for the first registered digit; by the release of steering-out relay 229 following the transmission of impulses for the second digit; by the release of steeringout relay 309 following the'transmission of impulses for the third digit; by the release of steeringout relay 329 following the transmission of impulses for the fourth or last digit and the timing for trunk hunting between the transmission of digits has been allowed.

Upon the first release of relay I33, a circuit is established from ground on conductor I53, over the back contact of relay I33, conductor I65, right back contact of counting relay I46, right back contact of counting relay I48, right back contact of counting relay I44, winding of counting relay I45 to battery. Relay I45 upon operating looks through the winding of relay I44, front contact of relay I45, left back contact of counting relay I48 to ground on conductor I01, but relay I44 being shunted does not operate until relay I33 again operates. Upon the next operation of relay I33, relay I44 operates and extends ground from conductor I01, over the left back contact of relay I48, inner left contact of relay I44 to the armatures of counting relays I59 and I6I for affording locking ground for these relays, over the back contact of relay I6I to the armatures of counting relays I53, I and I51 for locking these relays when operated and at its outer left contact connects ground from conductor I01 over conductor I66 to battery through the winding of relay I34. Relay I34 upon operating opens one point in the out-pulsing circuit thus placing this circuit under the control of impulsing relay I32. The first impulse generated by the release of relay I32 is thus absorbed by relays I44 and I45, succeeding impulses transmitted. by the successive operation and release of relay I32 being efiective to cause the vertical stepping of the first selector switch in the wellknown manner so long as relay I34 remains operated.

When steering-out relay 209 operated as previously described, to connect the control electrodes of tubes 265 to 208, inclusive, to the control electrodes of the decoder tubes, since only tube 205 was in a conducting condition as as sumed to register the first digit 1, 90-volt breakdown potential was applied to the control elec-' trode of decoder tube 245 over a circuit extending from battery I I2, over conductor I I3, through the tube 205, inner upper front contact of relay 209, resistance 249 to the right or-control electrode of tube 245 and since the left cathode of this tube is connected to a source of 45-volt negative potential, the tube ionizes and establishes a conductive path therethrough from the 90-volt positive battery H2, now connected to conductor 242, through the winding of decoder register relay 255 to the anode of tube 245, thence through the tube to the left cathode thereof and to the source of IS-volt negative potential. Register relay 255 thereupon operates. Since the other register tubes 206 to 208, inclusive, were assumed to be in a non-conducting condition, the other decoder tubes 246 to 248, inclusive, will not fire and consequently decoder register relays 256 to 1358, inclusive, remain unoperated. With decoder register relay 255 operated and relays 256, 251 and 258 unoperated, a registration is set up for the first registered digit I.

When impulsing relays I32 and I33 again re lease, relay I32 opens the out-pulsing circuit and relay I33 at its back contact connects ground over conductor I65, right back contact of counting relay I46, right back contact of counting relay I48, right front contact of counting relay I44, left back contactof counting relay I60, back contact of counting relay I50, conductor I10, back contact of register relay 251, back contact of register relay 256, right front contact of register relay 255, back contact of register relay 258, conductor 253, inner right back contact of counting relay I62, winding of counting relay I49 to battery. Relay I49 operates and looks. through the winding of relay I48, front contact of relay I49, right back contact of relay I54 to ground on conductor I01, but relay I48 does not operate in this locking circuit being shunted by ground over the back contact of relay I33. When relay I33 again operates, this shunt is removed and relay I48 operates, opening the locking circuits of relays I44 and I45 which now release in turn releasing relay I34. When relay I34 releases it shunts the contacts of impulsing relay I32 and the further operation of relays I32 and I33 is rendered ineffective to transmit impulses to the first selector switch. A single impulse has thus been transmitted.

The impulses generated by the operation of relay I33 are still effective and upon the next release of relay I33, a circuit is established from ground over its back contact, conductor I55, right back contact of counting relay I46, right front contact of counting relay I48, winding of counting relay I41 to battery. Relay I41 operates and locks through the winding of relay I46, front contact of relay I41, conductor I61, middle lower front contacts of steering-out relay 209 to ground on conductor I63. Relay I46 operates in this locking circuit upon the next operation of relay I33, opening at its outer left back contact the shunt around transfer relay 2I6 which now operates in the locking circuit of relay 209. The operation of counting relays I46 and I41 begins a 0.6 second timing interval to permit the first selector switch to hunt for an idle trunk in the first level of its bank to which its brushes have been raised.

Upon the next release of relay I33 ground is extended over its back contact, conductor I65, right front contact of relay I46, conductor I68,

lower back contact of transfer relay 3 I0, conductor I69, left back contact of counting relay I58, winding of counting relay I59 to battery. Relay I59 operates and locks through the winding of relay I58, front contact of relay I59, inner left front contact of counting relay I46 to ground on conductor I01 and on the next energization of relay I33, relay I58 operates in this locking circuit. With relay I58 operated, upon the next release of relay I33 the operating circuit previously traced to the left armature of relay I58 is extended over the front contact thereof, left back contact of counting relay I56 to battery through the winding of counting relay I51. Relay I51 now operates, locking through the winding of relay I56 and its own front contact, over the back contact of counting relay I6I and the inner left front contact of relay I46 to ground on conductor I01. On the next operation of relay I33, relay I 56 operates in this locking circuit. On the next release of relay I 33, the circuit over which relay I51 was operated is extended over the left front contact of relay I56, left back contact of counting relay I54 to battery through the winding of counting relay I55 which operates and looks through the winding of relay I54 and itsown front contact, back contact of relay I6! and inner left front contact of relay I46 to ground on conductor I01. On the next operation of relay I33, relay I54 operates in this locking circuit and at its right back contact opens the looking circuit of counting relays I48 and i 49 which release. On the next release of relay I33, the circuit over which relay I55 was operated is extended over the left front contact of relay I54, left back contact of counting relay I52 to battery through the winding of counting relay I 53 which operates and looks through the winding of relay I52 and its own front contact, back contact of relay I6! and inner left front contact of relay I46 to ground on conductor I01. On the next operation of relay I 33, relay I52 operates in the locking circuit of relay I53 and at its right back contact opens the locking circuit of steering-out relay 209 which releases, transfer relay 2 I being held energized over its lower winding and inner lower front contact to ground on conductor I05. Relay 209 upon releasing opens the locking circuit of counting relays I46 and I41 which now release in turn opening the locking circuits of relays I 52 to I59, inclusive, which release. Relay 209 upon releasing also disconnects the 90- volt source II2 of positive potential from the anode of decoder tube 245, restoring this tube and releasing the operated decoder register relay 255 and disconnects the control electrodes of tubes 205 to 208, inclusive, from the control electrodes of the decoder tubes 245 to 248, inclusive. If the second digit has now been registered in the tubes of the second tube register and transfer relay 223 has become deenergized, with transfer relay 2I0 operated, a circuit is closed for steering-out relay 229 extending from battery, winding of relay 229, upper back contact of transfer relay 230, lower front contact of transfer relay 2I0, lower back contact of transfer relay 223, conductor 240, inner left front contact of relay I09 to ground at the outer left back contact of counting relay I 46. Relay 229 operates and looks through the upper winding of transfer relay 230, inner lower front contact of relay 229, conductor 24I, right back contact of counting relay I 52 to ground on conductor I01, but relay 230 does not operate in this locking circuit. When impulsing relay I33 next releases and closes its back contact, a circuit is closed from ground on conductor I63 over the middle lower front contacts of relay 229, conductor 164, inner left back contact of relay I02 to the armature of relay I33, thence over conductor I65, back contacts of counting relays I46, I48 and I44 to battery through the Winding of counting relay I45. Relay I45 operates and looks through the winding of relay I 44, front contact of relay I45, left back contact of relay I48 to ground on conductor I01, relay I 44 operating on the next operation of relay I33 in this locking circuit and again causing the operation of relay I34 which, as before described, opens the shunt around the contacts of impulsing relay I32. nates the 0.6 second timing interval following the transmission of the first digit series.

Steering-out relay 229 upon operating ccnnects 90-volt positive potential from conductor H3 over its lowermost contact and conductor 242, thence through the windings of the decoder register relays to the anodes of the decoder tubes and over its upper four contacts connects the control electrodes of tubes 225 to 228, inclusive, of the second tube register to the control electrodes of the decoder tubes 245 to 248, respectively. It having been assumed that tubes 225 and 226 have been rendered conducting to register the second digit 3, decoder tubes 245 and 246 now ionize and the decoder register relays 255 and 256 operate over the discharge paths through these tubes. With counting relay I44 operating, on the next release of relays I32 and I33, the out-pulsing loop is opened at the contacts of relay i332 since relay I34 is now operated, and the circuit from ground over the back contact of relay I33 is extended over conductor I65, back contacts of counting relays I 46 and I48, right front contact of counting relay I44. left back contact of counting relay I66, left back contact of counting relay I50, conductor I10, back contact of register relay 251, front contact of register relay 256, left front contacts of register relay 255, conductor I1I, left back contact of counting relay I52 to battery through the winding of counting relay I53. Relay I53 operates and locks through the winding of relay I52, its own front contact, back contact of relay I6I, inner left front contact of relay I 44, left back contact of relay I48 to ground on conductor I01, but relay I 52 being shunted at the back contact of relay I33 does not operate at this time. On the next operation of relays I32 and I33, the out-pulsing loop is closed at the contact of relay I32 and the shunt of counting relay I52 is opened at the back contact of relay I33 and relay I 52 now operates in the locking circuit of relay I53. Relay I52 at its right back contact opens the locking circuit of steering-out relay 229. but relay 229 is maintained operated over its initial operating circuit previously traced. On the next release of relays I32 and I33. the out-pulsing loop is again opened and the previously traced circuit from ground over the back contact of relay I33 is now extended over the front contact of counting relay I52, right back contact of counting relay I60 to battery through the winding of counting relay I Relay I5I operates and looks through the winding of relay I59, its own front contact, inner left back contact of relay I46 to ground on conductor I01, but relay I50 being shunted at the back contact of relay I33 does not operate. On the next operation of relays I32 and I33 the outpulsing loop is again closed and the shunt of This termicounting relay I56 is opened whereupon it energizes. On the next release of relays I32 and I33 the out-pulsing loop is again opened and the previously traced circuit from ground over the back contact of relay I33 is now extended over the front contact of counting relay I50, conductor I12, back contact of register relay 258, conductor 253, inner right back contact of counting relay I62, winding of counting relay I46 to bat tery. Relay I49 operates and looks through the winding of relay I43, its own front contact, left back contact of relay I46 to ground on conductor I61, but being shunted at the back contact of relay I33, relay I48 does not operate. On the next operation of relays I32 and I33 the outpulsing loop is again closed and the shunt is removed at the back contact of relay I33 from around the winding of counting relay I48 which now operates, opening the locking circuit of relays I44 and I which release in turn releasing relay I34 and releasing counting relays I52 and I53, relay I52 again restoring the locking circuit of steering-out relay 229. When relay I34 released, the further operation of relays I32 and I33 is rendered ineffective to transmit impulses over the out-pulsing loop since the contacts of relay I32 are now shunted by the normal contacts of relay I34. The second selector has now been stepped three steps vertically.

On the next release of relays I32 and I33, the circuit from ground over the back contact of relay I33 is extended as traced over conductor I55, right back contact of counting relay I46, right front contact of counting relay I48 to battery through the winding of counting relay I41. Relay I41 operates and locks through the winding of relay I46, its own front contact, conductor I61, middle lower front contacts of steeringout relay 229 to ground on conductor I63 and relay I46 operates in this locking circuit upon the next operation of relay I33, opening at its outer left back contact the shunt around the winding of transfer relay 236 which operates in the locking circuit of relay 229 and opening at its inner left back contact the locking circuits of counting relays I48 to I5I, inclusive. The operation of relays I46 and I41 begins a 0.6 second timing interval to permit the second selector to trunk hunt.

Upon the next release of relay I33, ground is extended over its back contact, conductor I65, right front contact of relay I46, conductor I68, lower back contact of transfer relay 3H1, conductor I69. left back contact of counting relay I58 to battery through the winding of counting relay I59. In the manner previously described. upon the continued release and operation of relay I33, counting relays I59. I58, I51, I56, I55, I54, I53 and I52 operate in succession. Relay I52 upon operating opens at its right back contact the locking circuit of steering-out relay 229 which now releases. but transfer relay 23f! remains looked over its lower winding and inner lower front contact to ground on conductor I55. Relay 229 upon releasing opens the locking circuit of counting relays I46 and I41 which now release, opening the locking circuits of counting relays I52 to I59, inclusive, which also release. Relay 229 upon releasing also disconnects the 90-volt source IIZ of positive potential from the anodes of the decoder tubes 245 and 246 restoring them and releasing the operated decoder register relays 255 and 256 and disconnects the control electrodes of tubes 225 to 228, inclusive,

from the control electodes of decoder tubes 245 to 248, inclusive.

If the third digit has now been registered in the tubes of the third tube register and transfer relay 363 has become deenergized, with transfer relay 236 operated, a circuit is closed for steering-out relay 309 extending from battery, through the winding of relay 309, upper back contact of transfer relay 3I'Il, conductor 3I9, lower front contact of transfer relay 236, conductor 259, lower back contact of transfer relay 363, conductor 246, inner left front contact of relay I69 to ground at the outer left back contact of counting relay I46. Relay 369 operates and locks through the upper winding of transfer relay 3I6, inner lower front contact of relay 369, conductor 24I, right back contact of counting relay I52 to ground on conductor I61, but relay 236 does not operate in this locking circuit. When impulsing relay I33 next releases and closes its back contact, a circuit is closed from ground on conductor I63, middle lower front contacts of relay 369, conductor I64, inner left back contact of relay I52 to the armature of relay I33, thence over conductor I65, back contacts of counting relays I46, I48 and I44 to battery through the winding of counting relay I45. Relay I45'operates and locks through the winding of relay I44, front contact of relay I45, left back contact of counting relay I46 to ground on conductor I51, relay I44 operating on the next operation of relay I33 inthis locking circuit and again causing the operation of relay I34 which, as before described, opens the shunt around the contacts of impulsing relay I32. This terminates the 0.6 second timing interval following the transmission of the second digit series.

Steering-out relay 369 upon operating connects 90-volt positive battery from conductor II3, over its lowermost contact and conductor 242, thence through the windings of the decoder register relays to the anodes of the decoder tubes and over its upper four contacts connects the control electrodes of tubes 365 to 366, inclusive, of the third tube register to'the control electrodes of the decoder tubes 245 to 248, respectively. It having been assumed that tubes 366 and 368 have been rendered conducting to registerthe third digit 7, decoder tubes 246 and 248 now ionize and the decoder register relays 256 and 258 operate over the discharge paths through these tubes.

With countingrelay I44 operated, on the next release of relays I32 and I33, the out-pulsing loop is opened at the contacts of relay I32, since relay I34 is now operated, and the circuit from ground over the back contact of relay I33 is extended over I conductor I65, back contacts of relays I46 and I48, right front contact of relay I44, left back contact of relay I69, left back contact of relay I56, conductor I15, back contact of register relay 251, front contact of register relay 256, left back contact of register relay 255, conductor I13, winding of counting relay I5! to battery. Relay I5I operates and looks through the winding of relay I56, front contact of relay I5I, inner left back contact of relay I46 to ground on conductor I01, but relay I50 being shunted does not operate. On the next operation of relays I32 and I33, the outpulsing loop to the connector switch is closed at the contacts of relay I32 and the shunt of relay I56 is opened at the back contact of relay I33 and relay I56 operates.

On the next release of relays I32 and I33, the out-pulsing loop is again opened and the previously traced circuit from ground over the back contact of relay I33 is new extended over the front contact of relay I50, conductor I12, front contact of register relay 258, conductor I14, outer right back contact of counting relay I62, winding of counting relay I6I to battery. Relay I6I operates and looks through the winding of relay I60, its own front contact, inner left front contact of relay I44, left back contact of relay I48 to ground on conductor I01, but being shunted relay I60 does not operate. On the next operation of relays I32 and I33, the out-pulsing loop is again closed and the shunt around relay I60 is opened whereupon it operates. On the next release of relays I32 and I33, the out-pulsing loop is again opened and the previously traced circuit from ground over the back contact of relay I33 is now extended over the left front contact of relay I60, left back contact of counting relay I58 to battery through the winding of counting relay I59. Relay I59 operates and looks through the winding of relay I58, its own front contact, inner left front contact of relay I44, left back contact of relay I48 to ground on conductor I01, but being shunted relay I58 does not operate. On the next operation of relays I32 and I33, the out-pulsing loop is again closed and the shunt around relay I58 is opened whereupon it operates. On the next release of relays I32 and I 33, the out-pulsing loop is again opened and the previously traced circuit from ground over the back contact of relay I33 is now extended over the left front contact of relay I58, left back contact of relay I56 to battery through the winding of counting relay I51. Relay I51 operates and locks through the winding of counting relay I56, its own front contact, the right front contact of relay I58, the inner left front contact of relay I44, left back contact of relay I48 to ground on conductor I0I, but being shunted relay I56 does not operate. On the next operation of relays I32 and I33, the out-pulsing loop is again closed and the shunt around relay I56 is opened whereupon it operates. On the next release of relays I32 and I33, the out-pulsing loop is again opened and the previously traced circuit from ground over the back contact of relay I33 is now extended over the left front contact of relay I56,

I left back contact of counting relay I54 to battery through the winding of counting relay I55 and relay I54 operates on the next operation of relays I32 and I33. In a similar manner, upon the next releases and operations of relays I32 and. I33, relays I53 and I52 operate and the out-pulsing loop is opened and closed again. On the next release of relays I32 and I33, the out-pulsing loop is again opened and ground on the back contact of relay I33 is extended as traced to the left armature of relay I52, thence over the right front contact of relay I 69 to battery through the winding of counting relay I49. Relay I49 operates and locks through the winding of relay I48, its own front contact, the inner left back contact of relay I46 to ground on conductor I01, but relay I48 being shunted does not operate. On the next operation of relays I32 and I33, the out-pulsing loop is again closed and the shunt is removed at the back contact of relay I33 from the winding of relay I48 which now operates, opening the locking circuits of relays I 44 and I which release in turn releasing relay I34 and counting relays I52 to I 6|, inclusive. Seven impulses have now been sent to set the connector switch seven steps vertically. When relay I34 releases, the further operation of relays I32 and I33 is rendered ineffective to transmit impulses to the connector switch since the contacts of relay I 32 are now shunted by the normal contacts of relay I34. When counting relay I52 operated, it opened the locking circuit of steering-out relay 399, but relay 309 was maintained operated over its initial operating circuit. Upon the release of relay I52 the locking circuit of relay 309 is reestablished.

On the next release of relay I33, a circuit from round over its back contact is extended over conductor I65, right back contact of relay I46, right front contact of relay I48 to battery through the winding of relay I4'I. Relay I47 operates and looks through the winding of relay I 46 and its own front contact, conductor I67, middle lower front contacts of steering-out relay 309 to ground on conductor I63 and relay I 46 operates in this locking circuit upon the next operation of relay I33, opening at its outer left back contact the shunt around the winding of transfer relay 3I0 which now operates in the locking circuit of relay 309 and looks over its lower winding and inner lower front contact to ground on conductor I05. Relay I46 also opens at its inner left back contact the locking circuits for counting relays I40 to I5I, inclusive. The operation of relays I46 and I4? begins the timing interval, which in this case will be 0.4 second, before the final series of impulses is transmitted to the connector switch.

With counting relays I46 and I41 operated,when relay I33 again releases, ground is extended over its back contact, conductor I65, right front contact of relay E46, conductor I68, lower front contact of transfer relay 3I0, conductor 320, left back contact of counting relay I54, to the winding of counting relay I to battery and relay I55 operates. Upon the next operation of relay I33 relay I54 operates. In the manner previously described, upon the next release and operation of relay I33, countingrelays I53 and I52 operate in succession. Relay I52 upon operating opens at its right back contact the locking circuit of steering-out relay 309 which releases, opening the locking circuit of counting relays I46 and I4? which now release in turn opening the looking circuits of counting relays I52 to I55, inclusive which release. Relay 309 upon releasing also disconnects the 90-volt source II2 of positive potential from the anodes of the decoder tubes 246 and 248, restoring them and releasing the operate-d decoder register relays 256 and 258 and disconnects the control electrodes of tubes 305 to 308, inclusive, from the control electrodes of the decoder tubes 245 to 248, inclusive.

If the fourth and last digit has now been registered in the tubes of the fourth tube register and transfer relay 323 has become deenergized, with transfer relay 3I0 operated, a circuit is closed for steering-out relay 329 extending from battery, winding of relay 329, middle lower front contact of relay 3I0, lower back contact of transfer relay 323, conductor 240, inner left front contact of relay I09 to ground at the outer left back contact of counting relay I46. Relay 329 operates and looks through its inner lower front contact, conductor 24I, right back contact of counting relay I52 to ground on conductor I01. When impulsing relay I33 next releases and closes its back contact a circuit is closed from ground on conductor I63, next to inner lower front contacts of relay 329, conductor I64, inner left back contact of relay I02 to the armature of relay I33, thence over conductor I65, back contacts of counting relays I46, I48 and I44 to battery through the winding of counting relay I45. Relay I45 operates and locks through the winding of relay I 44, front contact of relay I45,

left back contact of relay I48 to ground on conductor I01, relay I44 operating on the next energization of relay I33 in this locking circuit and again causing the operation of relay I34 which, as before described, opens the shunt around the contacts of impulsing relay I32. This terminates the 0.4 second timing interval following the third digit series.

Steering-out relay 323 upon operating connects 90-volt positive potential from conductor II3 over its next to lower front contact and conductor 242, thence through the windings of the decoder register relays to the anodes of the decoder tubes and over its upper four front contacts connects the control electrodes of tubes 325 to 328, inclusive, of the fourth tube register to the control electrodes of the decoder tubes 245 to 240, respectively. It having been assumed that tubes 321 and 328 have been rendered conducting to register the fourth digit 9, decoder tubes 241 and 248 now ionize and the decoder register relays 251 and 258 operate over the discharge paths through these tubes.

With counting relay I44 operated, on the next release of relays I32 and I33, the out-pulsing loop is opened at the contacts of relay I32, since relay I34 is now operated, and the circuit from ground over the back contact of relay I33 is extended over conductor I65, back contacts of relays I45 and I48, right front contact of relay I44, left back contact of relay I60, left back contact of relay I50, conductor I10, right front contact of register relay 251, conductor 320, left back contact of counting relay I54, winding of counting relay I to battery. Relay I55 operates and looks through the winding of relay I54, front contact of relay I55, back contact of relay IBI, inner left front contact of relay I44, left back contact of relay I48 to ground on conductor I01, but relay I54 being shunted does not operate. On the next operation of relays I32 and I33 the out-pulsing loop to the connector is closed at the contacts of relay I32 and the shunt around relay I54 is opened at the back contact of relay I33 and relay I54 then operates. In the manner previously described upon the next release and operation of relays I32 and I33 relays I53 and I52 operate and the out-pulsing loop is opened and closed again. Relay I52 upon operating extends ground from the back contact of relay I33, over the left front contact of relay I52, right back contact of relay I to battery through the winding of relay I5I so that upon the next release and operation of relays I32 and I33 the out-pulsing loop is opened and closed again and counting relays I5I and I50 operate and lock. Relay I52 upon operating also opens the locking circuit of steering-out relay 329, but this relay remains operated over its initial operating circuit.

With counting relay I50 operated ground on the back contact of relay I33 is extended, as traced, to the left back contact of relay I50, thence over the left front contact of relay I50, conductor I12, front contact of register relay 258, conductor I14, outer right back contact of counting relay I52, winding of counting relay I5I to battery so that upon the next release and operation of relays I32 and I33, the out-pulsing loop is again opened and closed and the counting relays IISI and I50 operate and lock. Relay I5I upon operating opens the locking circuits of counting relays I52 to I55, inclusive, at its back contact and these relays release. In the manner previously described, upon successive releases and operations of relays I32 and I33, additional impulses are transmitted over the out-pulsing loop and counting relays I59, I53, I51, I56, I55, I54, I53, I52, I49 and I48 operate and lock in the order named. Relay I48 upon operating opens the locking circuits of relays I45 and I44 which release in turn releasing relay I34 and counting relays I52 to IOI, inclusive. Nine impulses have now been transmitted to set the connector in a rotary direction to the terminals of the wanted line. When relay I34 releases, the further operation of relays I32 and I33 is rendered ineffective to transmit impulses to the connector switch since the contacts of relay I32 are now shunted by the normal contacts of relay I34. Relay I52 upon releasing recloses at its right back contact the locking circuit of steering-out relay 329.

Relay I43 upon operating also establishes a circuit for relay I53 which may be traced from battery through the winding of relay I03, conductor I15, lowermost front contact of steeringout relay 325, conductor I15, left front contact of relay I48 to ground on conductor I01. Relay I03 now operates looking over its front contact to ground on conductor I03 and at its back contact removing the shunt from around the right Winding of relay IOI. With the right winding of relay I01 unshunted, decreased current flows over conductor I00 to signal the link circuit (not shown) that the sender has completed its functioning and may be released. The link circuit then releases and in the manner described in the Henry patent, previously referred to, removes battery from conductor I00 thereby releasing relay IOI which in turn releases relay I04. The release of relay I04 removes ground from conductors I05, I05 and I01 1 thereby releasing any operated relays of the sender thus restoring the sender to its normal condition.

What is claimed is:

1. In a telephone system, a first group of tubes, a cathode and a control electrode for each of said tubes, means for selectively applying breakdown potential to the control electrodes of said tubes to selectively render said tubes conducting, a second group of tubes each having a cathode, a control electrode and an anode, a register relay connected into the cathode-anode circuit of each of said second group of tubes, and means for connecting the control electrodes of said second group of tubes to the control electrodes of said first group of tubes whereby the tubes of the second group are selectively rendered conducting in accordance with the conducting condition of said first group of tubes to selectively operate said register relays.

2. In a telephone system, a first group of tubes,

a cathode and a control electrode for each of said tubes, means for selectively applying breakdown potential to the control electrodes of said tubes to selectively render said tubes conducting, means to maintain said tubes in a conducting condition after the withdrawal of said breakdown potential, a second group of tubes each having a cathode, a control electrode and an anode, a register relay connected into the cathode-anode circuit of each tube of said second group, and means for connecting the control electrodes of said second group of tubes to the control electrodes of said first group of tubes whereby the tubes of the second group are selectively rendered conducting in accordance with the conducting condition of said first group of tubes to selectively operate said register relays.

3. In a telephone system, a first group of tubes, a cathode and a control electrode for each of said tubes, a resistance network associated with the control electrode of each of said tubes, means for selectively applying breakdown potential to the control electrodes of said tubes to selectively render said tubes conducting, means including said resistance network for maintaining said tubes in a conducting condition after the withdrawal of said breakdown potential, a second group of tubes each having a cathode, a control electrode and an anode, a register relay connected into the oathode-anode circuit of each tube of said second group, and means for connecting the control electrodes of said second group of tubes to the control electrodes of said first group of tubes whereby the tubes of the second group are selectively rendered conducting in accordance with the conducting condition of said first group of tubes to selectively operate said register relays.

4. In a telephone system, a first group of tubes, each tube having a cathode and a control electrode, means for applying positive potential to the cathodes of said tubes, recording relays responsive to digit impulses for selectively applying negative breakdown potential to the control electrodes of said tubes to selectively render said tubes conducting, means for maintaining said tubes in a conducting condition after the release of said recording relays, a second group of tubes each having a cathode, a control electrode. and an anode, a register relay connected into the cathodeanode circuit of each tube of said second group, means for applying positive potential to the anodes and negative potential to the cathodes of the tubes of said second group, and means for connecting the control electrodes of said second group of tubes to the control electrodes of said first group of tubes whereby positive breakdown potential is applied to the control electrodes of tubes of said second group through such tubes of said first group as have been rendered conducting to selectively render said second group of tubes conducting for selectively operating said register relays.

5. In a telephone system, a first group of cold cathode gas-filled tubes, each tube having a cathode and a control electrode, means for applying positive potential to the cathodes of said tubes, means for selectively applying negative breakdown potential to the control electrodes of said tubes to selectively render said tubes conducting, a second group of cold cathode gasfilled tubes each having a cathode, a control electrode and an anode, a register relay connected into the cathode-anode circuit of each of said second group of tubes, means for applying positive potential to the anodes and negative potential to the cathodes of said second group of tubes, and means for connecting the control electrodes of said second group of tubes to the control electrodes of said first group of tubes whereby positive breakdown potential is applied to the control electrodes of tubes of said second group through such tubes of said first group as have been rendered conducting to selectively render said second group of tubes conducting for selectively operating said register relays.

6. In a telephone system, a plurality of groups of tubes, a cathode and a control electrode for each of said tubes, means for selectively applying breakdown potential to the control electrodes of each group of tubes in succession to selectively render tubes of each group conducting, a further group of tubes each having a cathode, a control electrode and an anode, a register relay connected into the cathode-anode circuit of each of said latter tubes, and means for connecting the control electrodes of said latter tubes to the control electrodes of said groups of tubes in succession whereby said latter tubes are selectively rendered conducting to operate their associated relays'in accordance with the conducting condition of said groups of tubes.

7. In a telephone system, a, plurality of groups of tubes, a cathode and a control electrode for each of said tubes, means for selectively applying breakdown potential to the control electrodes of each group of tubes in succession to selectively render tubes of each group conducting, a further group of tubes each having a cathode, a control electrode and an anode, a register relay connected into the cathode-anode circuit of each of said latter tubes, and a chain of steering-out relays for connecting the control electrodes of said latter group of tubes to the control electrodes of each of said groups of tubes in succession whereby said latter tubes are selectively rendered conducting to operate their associated relays in accordance with the conducting condition of said groups of tubes.

8. In a telephone system, a plurality of groups of tubes, a cathode and a control electrode for each of said tubes, recording relays selectively responsive to each successive series of incoming impulses, a group of recording conductors, means responsive to each operation of said relays for selectively applying potential to said conductors, steering-in relays operable in succession in re sponse to each operation and release of said recording relays for successively connecting said group of conductors with the control electrodes of each group of tub-es whereby the potential on said conductors is effective to selectively render tubes of each group conducting, a further group of tubes each having a cathode, a control electrode and an anode, a register relay connected into the cathode-anode circuit of each of said latter tubes, and a chain of steering-out relays for connecting the control electrodes of said latter group of tubes successively to the control electrodes of each of said groups of tubes whereby said latter tubes are selectively rendered conducting to operate their associated register relays in accordance with the conducting condition of said groups of tubes.

9. In a telephone system, a plurality of groups of tubes, a cathode and a control electrode for each of said tubes, means for applying positive potential to the cathodes of said tubes, means for selectively applying negative breakdown potential to the control electrodes of each group of tubes in succession to selectively render tubes of each group conducting, a further group of tubes each having a cathode, a control electrode and an anode, a register relay connected into the cathode-anode circuit of each of said latter tubes, means for applying negative potential to the cathodes of said latter tubes, a chain of steeringcut relays, means for successively operating said steering-out relays, and means controlled by said steering-out relays for connecting the control electrodes of said latter tubes to the control electrodes of said groups of tubes in succession and for applying positive potential to the anodes of said latter tubes whereby positive breakdown positive potential is applied to the control electrodes of said latter tubes successively through such tubes of each of said groups as have been rendered conducting for successively and selectively operating said register relays.

10. In a register sender, a plurality of groups of tubes serving as registers, means operative in accordance with the successive series of incoming impulses to selectively render tubes of each group conducting, a further group of tubes, a group of register relays for controlling out-pulsing series of impulses associated with and controlled by said latter tubes, and means for associating said latter group of tubes with said groups of register tubes in succession whereby said latter tubes. operate said register relays to control out pulsing in accordance with the registrations recorded by said groups of tubes.

11. In a telephone system, a plurality of groups of tubes, a cathode and a control electrode for each of said tubes, recording relays selectively responsive to each successive series of incoming impulses, a group of recording conductors, means responsive to each operation of said relays for selectively applying potential to said conductors, a chain of steering-in relays operable in succession in response to each operation and release of said recording relays for successively connecting said groups of conductors with the control electrodes of each group of tubes whereby potential on said conductors is efiective to selectively render tubes in each group conducting to register said series of incoming impulses, a further group of tubes each having a cathode, a control electrode and an anode, a register relay connected into the cathode-anode circuit of each of said latter tubes for controlling the transmission of outgoing, series of impulses, and a chain of steering-out relays for connecting the control electrodes of said latter group of tubes to the control electrodes of each of said groups of tubes in succession whereby said latter tubes are selectively rendered conducting to operate said register relays in accordance with the conducting condition of said groups of tubes.

THOMAS L. DIMOND.

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