US1647363A - Telephone system - Google Patents

Description

Nov. 1, 1927. I 1,647,363

" E. JACOBSEN ET AL v TELEPHONE SYSTEM Filed June 5, 1925 2 Sheets-Sheet l Mrekzfms:

[727/7 Jaws! j/Mu/ 15 Spar/y 1,647,363 E. JACOBSEN ET AL Npv. 1, 1927.

TELEPHONE SYSTEM 0 2 Q 4 a 68 mg w e m a W W J z 3 m M w mfi 5 t JmL w H P Filed June 5, 1925 wmm b S w Patented Nov. 1, 1927.

,EMIL' JACOBSEN, or roar wAsnmeToi esion.

n) ARTHURB. sen-REY; or NEW YORK,

n. Y., ASSIGNORS TO WnsrER-n ELECTRIC COMPANY, INCORPORATED; or NEW Yonn,-1\T.Y.,AooRBoRATIon on NEW YORK. I,

TELEPHONE sYs'rnM f 1 Application filed Jane 5, 1925.; Serial no. 35,074..

This invention relates to automatic telephone systems and more particularly to a system arranged for extending calls from dial stations in a three-wire ofiice to an intercepting operators position of a two Wire ofiice. u

In certain existing step-by-step machine switching areas there have been installed step-by-step machine switching equipments designed to operate on the so-called three- Wire basis, that is, controlling impulses from substation dials are directed over'two one of the talking conductors and a ground return. I

necessary to add additional equipmentto care for the growth-0f the exchange; it is desirable and more economical to install equipment of a more modern character which is designed to function over full metallic'circuits extending to the substations eliminating the ground return. When such modern euipment is added to an existing exchange it becomes necessary to: provide means whereby the two types of apparatus may, function together so that all subscribers may have access-to each. others lines and to special service operators positions."

The object of this invention is therefore to provide an improved means: for handling calls from adial station in a three-wire.of

.ficc to a dial stationin atwo-wire ofiice includingthe feature that when such a callis routed to anintercepting operator in atwowireotfice, means'are provided for controlling the supply of talking battery to; the calling subscriber in the three-wire oflice."

Fig. 1 of the drawings shows the subscribers station A'in the upper left-hand corner connected to a line switch LS. a three-wire first selector FS having brushes 3, 4 and 5 which has access" to a,three. wire repeater circuit R shown i-n' the center of this drawing. The repeater circuit is con nected by means of trunk line T,iwhich is shown in schematic form, to a secondary selector SS of the two-wire type which has brushes 6. 7 and 8. The secondary'selector has access to a combination toll and local connector circuit C shown at the left of Fig. .2, having, brushes 200, 201 and 202. The connector C has access to an intercepting operators trunk IOT shownending in'j-ack In such areas, when it becomes 210 "with which the intercepting operators cord OGis used. The dial 1 at the subscribers station Ain Fig.1is of a type disclosed m'the patent to Erickson #909382 and will not be described in detail herewith the e rception of calling attention to the fact that impulses are sent first over oneside of the lineand then over the opposite side.

A clearer idea of the operation of these. clrcults may be had from the following detailed description. I When the calling subscriber A removes the receiver from the switchhook the line switch LSfoperates' in.

thefma'nner well known in the art'and con.- nects subscriber. A through to the first selector 'FS. Line switch LS closes a cir-.

cuit. from ground through the winding of relay 22 over lead 36 through the normal rotary contact of off-normal spring 37, con

ductor 38, winding of relay 13 to battery.

vertical relay 30 closes a circuit from ground on the middle contact of spring combination 29 through the winding of vertical magnet 23 to battery on the back conj tact ofrelease magnet 24. Verticalrelay 30 follows the impulses from the. dial 1 and transmits them to the vertical magnet 23 thereby-stepping the first selector switch a certain number of steps in a verticaldirew follows thisimpulse from the dial at subscribefis station A V and connects ground through the middle contact of spring combination 29, through the winding of rotary magnet 26 to battery on the back contact of release magnet 24, thereby causing rotary magnet26 to operate. When rotary magnet 26 operates it closes the contacts of private magnet 25 which are mechanically connected as disclosed, thereby closing a circuit from battery on the back contact of release magnet 24, through the winding and outer front contact of private magnet 25, through the winding of release relay 27 to brush This circuit is closed for purposes hereinafter described. After the impulse has been received by relay 21, it releases, opening the circuit of rotary magnet 26, which releases, in turnpermitting the contacts ofprivate magnet 25 to open if the trunk upon which brushes 3, 4 and 5 are resting is idle.

Should the first trunk of the group be busy, ground will be connected to contact 32 from another selector such as FS, thereby holding private magnet operated over the circuit previously traced A self interrupting circuit is now closed for rotary magnet 26 extending from battery at the back contact of release magnet 24, winding and contacts of magnet 26 to ground on the inner contact of private magnet 25. Magnet 26 rotates the brushes stepbystep over terminalsof busy trunks. As soon as an idle trunk is found brush 5 encounters no ground and private magnet 25 releases opening the circuit of rotary magnet 26 causing the brushes of the selector to stop rotating. Upon the first rotary step, off-normal springs 37 operate. During the rotary movement of the selector relay 13 is held operated over a circuit extending from battery through the winding of relay 13, alternate contacts of springs 37, .to ground at the inner contact of magnet 25. When the rotary movement ceases and magnet 25 deenergizes, the circuit of relay 13 is opened and it releases to disconnect the windings of relays 21 and 30 from the subscribers line and to cut the line conductors through to the brushes 3, 4.

' Assuming the trunk terminating in repeater R to be idle, a circuit will be closed from battery through relay 31, resistance 39,

contact 32, brush 5 through the winding of '19 to battery through relay 45.

"relay 27 to ground on the outer back contact of private magnet 25, but due to the resistance 39, relays 27 and 31 do not operate atthis. time. A circuit is also closed from ground on the outer back contact of relay 25 through the winding of relay 27, brush 5, terminal 32,winding of relay 43, left back contacts of relays 40, 41 and 44, back contact of relay 43, right back contact of relay Relay 45 energizes in this circuit but relay 43 does not. The relay 45 closes a locking circuit for itself from battery, through its winding, and right front contact, contact of relay 49 to ground at the contact of magnet 25 over the circuit previously traced, and closes a circuit from battery through the winding of relay 19, left front contact of relay 45, left back contact of relay 44 and thence over the circuit above traced to ground on the outer back contact of private magnet 25.

Relay 19 operates and looks over a circuit from battery through its winding and right front contact, back contact of relay 43, left back contact of relay 44 and thence to the same ground hereinbefore traced. A circuit is closed for relay 16 over a parallel'circuit from battery, through its left winding,,left front contact of relay 45 and thence to ground on relay 25. Relay'16 does not receive sufficient current to operate at this time.

The operation of relay 19 closes a loop circuit for operating relay 33 in secondary selector SS. This loop maybe traced from battery through the left winding of relay 33, outermost back contact of relay 9, conductors 52 and 14, coil 15, right winding of relay 16, conductor 17, left back contact of relay 18, left front contact of relay 19, conductor 57,fmiddle back contact of. relay 9 to ground through the right winding of relay 33. Relay 16 does not operate in this circuit due to the fact that its windings are in opposition with each other at this time.

l/Vhen subscriber A operates the dial 1. for the second digit, impulses are received over brush 3 at first selector FS, over terminal 12, left back contact of relay 4'? to bat ery through the winding of relay 18. Relay 1S follows the impulses and opens and closes the loop traced above. The operation of relay 18 also closes an obvious circuit for the operation of relay 34, which relay 34 being slow to release remains operated during pulsing and opens conductor 53 at its left back contact and at its left front contact short-circuits the right winding of relay 16 and coil 15 in order to eliminate their impedance from the loop while impulsing. The opening and closing of the above traced loop operates relay 33 which closes an obvious circuit for the operation of relay 20. Relay 20,, being slow to release, remains operated during the impulsing period and closes a circuit for transmitting impulses over an impulse circuit 1 from ground on the back contact of relay 9, back contact of relay 33, right front contact of relay 20, winding of relay 54 to battery through the winding of primary magnet 35, thereby stepping the brushes 6, 7 and 8 of a second selector SS to the desired group. Relay 54 operates but on account of its being a slow to release relay it does not follow the pulses but remains operated throughout the dialing period.

As soon as the off-normal contacts 36 are closed following the movement of the switch shaft one step in a vertical direction, a circuitis closed to operate relay 56 as follows: battery, through the winding of relay '56.

lower contact of toll-normal springs 36, front contact of relay 54-, left front contact of re- .lay to ground. Relay 56*operated locks as follows: battery, Winding of relay 56', lower contact of off-normal spring 36, back contact of secondarymagnet 37, upper contact of relay 56: to ground on the right'back contact of relay 9. The primary movement of the switch is completedat the end of the impulse-train and the impulse relay 33 remains operated, opening the circuit through .the'primary magnet 35 and relay 54,1'el'easing the magnet and the relay- In releasing, relay 54 closes a circuit to operate the secondary magnet37 asfollows battery, wind;

ing of secondary magnet 37 front contact of relay 56, back contact of relay 5 4 to ground at the left front contact of; relay 20. The: secondary magnet 37 in operating opens at its contact the locking circuitfor relay 56, thereby releasing it, relay 56'- in turn opening the circuit. of magnet. 37... The. op eration and release'of magnet 37 causes the brushes 6, 7 and; 8 "of selector switch S8 to advance. one step to the first trunk terminals of the. selected group. Should the first trunk be busy, .ground be found on. the sleeve terminal (Corresponding to terminal 224) and be connected to brush 8- A; circuit WfllIHOW beclosed by way of the sleeve terof the busy trunk to reoperate relay 56- as follows: battery, winding of relay 56,

lower contact of off-normal springs 36, back contact of secondary magnet -37, innermost left back contact of relay 9, brush 8 to ground on thesleerve of the busy trunk. Re.-

lay 56 operated, locks over the locking circuit previously traced and closes the circuit previously traced for the secondary magnet '37, which operates and again opens at its back contact the locking circuit for relay 56, releasing the relay which in opens the circuit for secondary magnet37. which likewise releases. The release of magnet 37 advances brushes 6, 7 and 3 to the terminals of the next trunk the. group. This cycle of operations continues until an idle. trunk is found. r I V "Let us assume: that the brushes'6,7ancl 8 are now resting upon terminals 208, 209 and 224 and that the connector C is idle, in

which case terminal 210 will be free. from ground. A circuit will now be closed to operate relay 9 follows 1 battery, winding; of relay 56, lower contact. of off-normalsprings 36, back contact of secondary magnet 37.

winding of relay 9 to ground through the left front contact of relay 2.0.1 Relay 56 will not operate at this time due to the high resistance of the winding; of relay 9. Relay 9 operated extends the connectionv by way of brushes 6 and 7 to terminals 208 and 209 through its left outermost and middle front contacts. The impulse relay 204 of. the connector circuit C will now operate over-a circult -"from battery through. the winding and operates under control of relay '18 wvhich is in turn under control of the subscribers dial. Relay 204 operated, operates relay 207 over an obvious circuit.

Relay1207; connects ground from its inner I right front contact: to terminal 224 thence over brush '8, the. inner left front contact and Winding of relay 9 to battery through the winding'of' relay 56. as previously traced for holding switch SS in its operated-position and to prevent: the connectorOfrom being seized by another second selector; It. is to be noted that upon the operation of relay 9,

the circuit of relay 33 was opened where- 1 upon relay released in turnreleasingrelay 20. Relay 20- beingslow to release, how-1 ever did not open thev circuit of relay 9'unti1 after relay 9 became looked over brush 8. Relay 20-7 also opens the release circuit for the: connector switch and preparesfa circuit for the operation of'thevcr'tical magnet 2'14 through its outer; right front contact, condoctor 211, lower normal contact. of-the olfnormal switch 212 through the winding of relay 213 and the windingof primary magnet 214 to battery. v I

The-first set of impulses sent out by the calling station after the seizure of this switch operates relay 204 which operates the pri- 7 mary magnet 214 to step the shaft in a ver- 'tical direction and operates relay 213 in series with. the primarymagnet 214;. Relays 207 and 213 remain operated during this series of impulses since they areslow to release. VVhen the shaft moves accordance with the firstdligit in a vertical direction, the original circuit through the off-normal springs for; operating primary magnet 2141' s transferred from. the. lowernormal contact to the lower alternate. cont-act'of off-normal.

switch 212, andthe: left front contact ofrelay- 213,. whichcircuit is maintained due to. the

slow release-action of relay 213. 7 After all by the dial are finished, relay 213releases and prepares a circuit for operating the secondary magnet 215, extending from battery through magnet 215-, innermost right back "Contact of relay 216, inner right back contact of relay 217,. left back contact of relay 213, lower alternate contact of off-normal switch 212, conductor 211, outer right front contact of relay 207 to ground on the back contact the: remaining pulses of this series sent out of julsing relay. 204.. Thesecond set of im: pu ses'- received byv connector G from the calling station will now operate the secondary magnet 215 and rotate'the shaft according to the number of impulses dialed. Re lay 207 also remains operated during the operation of the secondary magnet on account of its slow release feature. Relay 218 also operates in the pulsing circuitin parallel'witlrthe secondary magnet 215 and due to its slow release feature remains operated during the pulsing period to close a circuit for testing the-called trunk. This-circuit may be traced from .battery through the Winding of relay 217, next to inner right back contact of relay 216, right frontcontact of relay 218,,conductor 219 to brush 202.

If the called line is busy, ground is found on terminal 220, thereby operating'relay 217. Belay 217 operated, locks to ground upon the release of relay-218 over a circuit from battery, Winding of relay: 217, right back contactof relay 216, right back contactof relay 218, outer right front contact of relay' 217, to ground at the inner right front'contact of relay 207. The operation of-relay 217 closes a circuit from. ground through the Windingof tone coil 223, left front contact of relay 217, conductors 225 and 240 terminal 209, brush 6, middle front contact of relay 9. conductor 57, left front contact of relay 19, left back contacts of relays-18 and 34,,ter-minal 12, brush 3, outer'back' contact of relay 13, conductor 51, terminal of line switch LS conductor 27, subs-cribers emu-311a. conductor 28', terminal of'line switch, conductor 50, inner'back contact ofrelay 13, brush 4, terminal 11, right back contact of relayv 47, to battery through relay 31, giving the subscriber a tone as an indication of a busy condition.

If the called trunk TOT is' idle, battery will be connected to terminal-220,'thereby preventing the operation of relay 217 Relay 216 will then operate in'a-circuit-from battery, terminal 220, brush 202,'right back-- contact of relay 218, right Winding of relay 216, outer right back contact of relay 217, conductor 227 to ground on the inner right front contact of relay 207. Upon its operati on relay 216 looks over its left Winding'and inner left contact, middle alternate contacts "of off-normal springs 212, to ground at the left front contact of relay 207 and connects ground from its outer right front contact/ to brush 202, thereby making the'intercepting operators trunklOT busy. Heretofore, re-

lay 216 Wasonly partially operated, the only contacts closed being the left innermost frontconta'ct and the outer right contact. lVith' the closure of the locking circuit through its left Winding, relay 216 completely operates its remaining contacts and is maintained energized untilthe switch releases. The operation of relay 216 connects leads .228'and' 229 to-brushes 200 and 201 through its two outer, left front contacts. The'operation of relay 216 opens'the circuit for the secondary magnet 215 through its innermost right back-contact, thereby preventingany false pulses from stepping the switch further. It also opens the circuit for relay: 217 at its next tov inner right back contact, thereby preventing busy tone from being impressed upon the calling subscribers line and also opens .thecircuit to prevent releasemagnet 255- from operating and releasing the connector. I

. Positive or negative superimposed ringing current is now impressed on the selected trunk through theouter right back contact of relay-230. This circuit maybe traced from ringing current source 280 through the right Winding of relay 230, outer-right back contact of relay 230, conductor I 229, left front contactof relay 216,-,brush- 201, terminal 221,.right back contact of relay 231, I

contact of relay 230. This'ringing'current causes theoperation-of relay 237 lighting lamp 238 in an -obvious clrcu t. Belay 237 also locks ina 011811113 from battery on the outer left back contact of relay 231, left winding .of relay 237 to ground on'its left front'contact, thereby holding relay 237 op"- erated after theringing current ceases.

When I the intercepting operator inserts the plug of cord 232 into jack 210 in-response to the lamp signal 238, relay 233 operates over a'circuit from'battery'through the Winding of relay 233, right back and left back contacts of relay 241, thence over the ring of plug 232, ring of ack 210, inner left back contact of relay 231 to ground. Another 1 circuit: will be' closed from battery, through the left back contact of relay242, conductor 253, Winding and left back contact of relay 244, left back contact of relay 241, thence over the circuit above traced to ground through the inner left back contact of relay 231." The operation of relay 244 closesa circuit for the operation of relay 231 from ground through the Winding of relay tion of relay'231 opens the circuit for relay,

237, thereby releasing it and extinguishing lamp 238, and closes the ring of jack 210 through its inner left-front contact to terininal 221. The operation of relay 244 closes a holding circuit for relay 233 from ground on the inner right front contact of relay 244, right back contact of relay 241 tobattery through the Winding of 'relay 233, and a circuit from the-ringing source 280 through I the right'winding and outer right back contact of relay 230, left middle outer front contact of relay 216, brush 201 terminal. 221, inner left front contact :of relay 231, rings of jack-and plug, leftbackcontact of relay 241 to ground at the inner right front contactof relay 244. Relay 230 locks over its left winding and contact to ground on the left front contact of relay 207 The operation of relay 230 disconnects the ringing source and ground from the conductors 228 and 229 and closes the talking circuit through its contacts. The operation of relay 244 also closes a circuit for operating the slow operating relay 245 which operates slow' operating relay 241. These two relays are slow to operate to' allow the left back contact *of relay 241 to remain closed a sufficient length of time to operate relay 230 in the connector C, before the contacts open;

Thev operation of relay 233 also opens the tip of'theicord and operates theslowxto'release relay 243 in an obvious circuit through its left front contact; Relay 243 in turn operates relay 234 over an obvious circuit By this time relay 241 is completely operated thereby opening the holding circuit forrelay 233 allowing it to release in turn terminal 208, brush 7 outer left front con tact of relay 9, conductor 52, right back contact: of relay 34, winding of relay 49, to

ground on the-outer right" back contact of relay44. vRelay 49 operated, opens'the looking circuit-for. relay which, closes an op-. erating circuit for relay 47 from ground on terminal 32, winding of relay 43, left back contacts of relays 40, ;41 and 44, back contact of relay 43 as this'is slow to operate, right front; contact ofrelay 19 left back contact of relay 45, to battery through relayj47. Relay 47 operated, connects talking battery back-.to 1 the calling subscribersj' line'A through the windings of relay 44. Relay 44 operates in a circuitextendingfrom battery through its left winding, the left contact of relay 47, terminal 12, brush 3, thence to the callingline, returning over brush 4, terminal 11, inner right-front contact of relay 47 right winding of relay 44 to ground. Relay 44 v in operating establishes'a locking circuit for relay 47 from-battery, winding and outer right contact of relay '47 to ground at the outer right front contact of relay 44, and closesa circuit for relay 'extending from a station battery through the winding of relay 40 to ground/at the inner right "contact of; relay 44. With relays '44 and '47 operated relay 19 is held operatedover a circuitextending from battery'through the winding of relay; 19, left back contact, of relay .45, to; ground throughthe outer right contacts of relays 44- and 47. Relay '40. closes an obvious circuit.

for relay 41 which at itsright'contact closes an additional holding circuit for relay 19- extending from ground at the right contact.

of relay 41, left frontcontactof relay 44, back contact of relay 43, thence to battery through the Winding and right front contact of relay 19. Relay 40 upon :operating'also opens the circuit extending through the. winding of relay 43 to terminal32 which is. later effective for releasing switch PS. The; operation of relay44 also opensthe circuit of relay :49.

. At the cord circuit upon the operation'of relay 241 a bridge circuit consisting of re lays 250 and 251jand coil 236 was connected across the tip and ring of the cord. The operation of relay 241 also opens the circuit for relay 233.

When the tip and ring ofthe cord'are closed by the operation of relay 241. a circuit is'closed foroperating'relay 251 from battery throughthe right winding of relay 203, conductor'239, inner right -front contact of relay 230, conductor 228, outermost left I front'conta'ct of relay 216, brush 200, .ter

minal 222, tipof .jack 210, tip of cord 232, right backcontacts of relays 233 and 234, conductor sea-c011 236, windings of relays 250 and 2,51, conductor 249 left front contact of relay 241, rin of cord 232, ring of jack 21 0, innerleft fi'ont contact of relay'23l, terminal.- 221, brush201,left front contact contact of relay 230, conductor 240. to ground through 1 the left winding of relay. 203.

' of relay 216, .conductor -229',outer right front Relays 203 and 250; do not. operate in this circuit as'the'resistan-ce of relayf250 'is too highito allow relay 203 to operate and the' battery polarity is not correct for the opera tion'of relay 250. Relay 203 fails to operate on a call to-an operator but does operate on to station call as. described hereafter- 'Shoulcl a call be initiated to'a subscriber in a two-wire office (not shown) instead of I to an intercepting operator, the brushes 200,

201 and 202 will come to. rest on the tip, ring and sleeve terminals,respectively, of .a sub; scribers station. '(not shown). The operation of the first selector, repeater, second selector and connector will be'the'sarne as described above up to and including thecon nection of ringing source 280 to the-sub scribers line. When the-called subscriber answers, relay 230 operates and disconnects I I the ringing current as. described above.

Relay 203 will also operate in a circuit from 7 ground through its left winding, conductor 240, outer right front contact of relay 230, conductor 229, left front contact of relay 216, brush 201, through the subscribers loop, brush 200, outer left front contact of relay 216, outer right front contact of relay 230, conductor 239 to battery through the right winding of relay 203. Relay 203 operates and closes a locking circuit for relay 230 and reverses the circuit for relay 204 hereinbefore traced through the right winding of relay 16. As the windings of rela 16 are now aiding each other, the relay wil operate and in turn operate relay 47 over an obvious circuit. The operation of relay 47 connects the windings of relay 44 across the brushes 11 and l2-for supplying talking battery to the calling subscriber. Relay 44 will operate in this circuit and close an obvious circuit through its inner right front contact for operating relay 40. Relay 40 in turn operates relay 41 over an obvious circuit and opens the disconnect circuit hereinafter described. Relay 44 also closes a locking circuit for relay 47 from ground on its outer right front contact and winding of relay 47 to battery thereby holding the relay operated until the called subscriber disconnects.

When the call is finished and the calling subscriber hangs up ground is connected momentarily to both sides of the'line at substation A thereby holding relay 44 operated. When relay 44 finally releases the locking circuit for relay 47 is opened releasing the relay thereby opening the holding circuit for relay 19. The release of relay 44 also opens the circuit for relay in turn releasing relay 41. Both of these relays are slow to release but the adjustment of relay 40 :.is such that it will release before relay 41.

Therefore a circuit will be closed from battery through resistance lamp 42, left front contact of relay 41, left back contact of relay 40, winding of relay 43, terminal 32, brush 5,

release relay 27 to ground at the right front contact of relay 25. The release magnet 24 is now operated over a circuit from battery thru the winding of release magnet 24, front contact of relay 27 conductor 36 to ground thru relay 22 in the line switch. The opera tion of the release magnet 24 restores the apparatus of the first selector F8 to normal.

The opera-ted relays of the repeater R are now in normal condition. w

Upon the release of relay 19 the circuit of relay 204 of connector G is opened. The release of relay 204v releases relay 207 and relay 216 thereby closing a circuit for the operation of release magnet 255 which. ex tends from battery, winding of magnet 255, upper contacts of off-normal switch 212, back contacts of relays 216, 207 and 204 to ground. The operation of release magnet 255 causes the brushes of connector C to be restored to normal. The release of relay 207 discon nectsground from terminal 224 allowing re lay 9 to release. Relay 9 released closes .a

circuit from ground over its right back conthe brushes of the second selector SS to return to normal.

Relay 207 released also opens the locking" circuit for relay 230. The release'of con-.

tacts 222, 221 and 220 by brushes 200, 201

and 202 opens the loop circuit for relay 251 hereinbefore traced. The release of relay 251 closes a circuit for relay 242 from ground on the innerright front contact of relay 244,-

right front contact of relay 241,- left back contact of relay 234, back contact of relay 251 to battery through. the winding of relay 242 operating it. The operation of relay 242 lights lamp 265 as a signal to the intercepting operator to disconnect, opens the circult. of relay 244 and. establishes an, alternative circuit from battery through the left front contact of relay 257, sleeves of plug 232 and jack 210 to ground through relay 231. Relay 257 energizes to establish .an

obvious holding circuit for relay 242 for maintaining lamp 265 lighted after relay 244 releases, in turn releasing relays: 245 and 241.

in responseto the illumination of disconnect lamp 265, the operator withdraws plug 232 from jack 210, releasing relays 231' and 257, relay 257 in turn releasing relay 242 and extinguishing the lamp 265. paratus is now in normal condition.

What is claimed is: V V 1. In a telephone system, a subscribers station, an operators position, means including switching mechanism for extending a con nection from saidsubscribers station to said- All apoperators position, means associated with. sa1d swltclnng mechanism for supplying talking battery to said subscribers station, a cord circuit at said operators position for further extending said connection, and 7 means operative in responseto the associa-- tion of said cord circuit with said extended connection to render effective said talking battery supplying means.

2.;1-11 a telephone system, a subscribers sta-' tion, an operators position,means including switching mechanism and a repeater for extending a connection from said subscribers station to said operators position, means associated with saidrepeater for supplying talking battery to said subscribers station, a cord circuit at said operators position for further extending said connection, and means operative in response to the'association of said cord circuit with said extended connection to render efi'ective said talking battery supplying means. 7

3. Ina telephone system, a subscribers station, an operators position, means including station to said 0 erators osition means associated with said repeater for supplying talking battery torsaid subscribers station comprising a source of talking current, a relay for connecting said source of current to that part of said connection extending to said subscribers-station, and a relay responsive to ringing current for controlling said first relay, a cord circuit at said operators position for further extending said connection, a source of ringing current at said cord circuit, and means operative upon the as- 'sociation of said cord circuit with said extended connections to apply said ringing current source to said cord circuit whereby said second relay is operated.

4. In a telephone system, a subscribers station, an operators position, means including switching mechanism and a repeater for extendmg a connection from said subscrlbers station to said operators'position, means associated with said repeater for supplying talking battery to said subscribers station comprising a source of talking battery and means initially responsive to ringing current to connect saidsource to said subscribers station, a cord circuit at said operators position, a source of ringing current in said cord circuit, and means momentarily operative upon association of said cord circuit with said extended connection to apply said 1 ringing current source to said cord circuit. whereby said talklng battery SOUI'CBHIS con 'nected to said subscribers station.

5. In a telephone system, a subscribers 'sta tion in a three-wire oflice, an operators position in a two-Wire office, means including switching mechanism for extendinga connection from said subscribers station to said operators position, means associated With said switching mechanism for supplying talking battery to said subscribe'rs station, a cord circuitat said operators position for further extending said connection, and means operative upon the association of said cord circuit with said extended connection to rendereflective said talking current supplying means.

tending a connection from saidsubscribers station to said operators position, means associated with said repeater for supplying talking battery to said subscribers station, a cord circuit at said operators position for further extending said connection, and

means operative upon the association of said cord clrcuit with sald connection to render effective said talking battery supply means. In witness whereof, we hereunto subscribe our names this 3d day ofJune, A. D., 1925.

EMIL JACOBSEN. V ARTHUR B. SPE RRY.

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