US1753334A - Telephone system - Google Patents

Description

T. v. CURLEY 1,753,334

TELEPHONE SYSTEM Filed May 10, 1928 2 Sheets-Sheet l April 8, 1930.

MARE/MAL /NVEN TOR. 77-/0MA5 l/UURLE) 5r WM Armmm April 8, 1930. T. v. .CURLEY 1,753,334

- TELEPHONE SYSTEM Filed May 10, 1928 2 Sheets-Sheet 2 g (M g i Q' g #vvmma:

' THDMA s l/ UURLE) Patented Apr. ,8, 1930 r r ce THOMAS V. CURLEY, OF BROOKLYN, NEW YORK, ASSIGN OR TO BELL'TELEPHONE LAB- ORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF YORK TELEPHONE SYSTEM Application filecl May 10, 1928. Serial No. 276,653.

This invention relates to telephone systems and particularly to improvements in trunking systems.

The object is to simplify theequipinent and to increase the reliability of operation in a toll trunking system serving coin lines.

In the past it has been the practice for the toll operator to collect the coins deposited by the calling subscriber in payment for the call by means of a key.

According to the present invention this system has been simplified and rendered more reliable by eliminating the operators collect key and providing means responsive when the i calling subscriber hangs up his receiver and the toll operator releases the connection by' the removal of a cord from the trunk at the distant oiiice or at the toll switchboard for collecting the coins. v

A feature of the invention is a trunk circuit in which the usual condenser, inserted between the outgoing windings of the usual repeating coil to provide a talking circuit path, is laced directly across the control relay windings between this relay and the contacts of the usual current reversing relay. This arrangement is to prevent discharges and charges from the condenser from falsely operating the control relay.

Another-feature is an arrangement for increasing the ampere turns on the marginal supervisory relay, controlled by the calllng subscriber during switchhook operation, without materially increasing the resistance in series with the line.

Another feature is an arrangement for preventing the interruptions, for coin collect or refund purposes, of the connection between the calling subscribers line and thecentral oiiice talking battery from producing clicks in the calling subscribers'receiver. For this purpose means is provided for opening the connection'between the talking battery and the repeating coil int-he line before said -in terruptions take place and for closing said connection aft-er said interruptions have ceased. r

The invention has been illustrated in the accompanying drawings in which Fig. 1

shows a trunk at an automatic ofiice arranged in accordance with this invention, a coin box subscribers station, and intervening automatic switches in diagrammatic form for seizing the trunk.

Fig. 2 shows the incoming end of this trunk..1 terminating in a ack at a toll operators position. A portion of the toll operators cord is also shown in this figure in diagrammatic form. I

V Adescription will now be made of the tune- 0 tions of the circuit arrangement shown by tracing a call from the calling coin box subscribers station Afthrough the switches LF and S at the automatic office-B, and through trunk T to the toll operators position'G. As -r5 the apparatus at the automatic office whereby calling subscribers may seize trunks such asT is not essential for the description of this invention, none of this apparatus has been illustrated except to indicate the brushes for the" "50 line finder LF and the selector S. None of the apparatus at the. toll operators position has been shown, except the answering plug of an ordinary cord circuit, as this equipment is not essential for the description thereof.

Assuming then that the subscriber at station A has deposited a coin to close a connecion to ground for the coin box magnet 5 to enable him to operate dial 6'; that he has dialed a certain code number to secure a con-" ito motion to a toll operator, and that the connection has been extended throughthe line finder LF and the brushes of switch S have seized the terminals f the trunkT. The first effeet-of this seizure will be that a connection 355 througa a comparati'vely high resistance will be momentarily closed for one winding of relay 8. The characteristics of thiswinding of relay 8 are such that while the resistance is very low, its. ampere turns with the high *-;& resistance of the circuit at this time-will not permit the relay to operate The momentary closure is efiected due to certain circuit operations in the selector S that of themselves are of no importance in connection with this inven-rt'; tion, except in so far that the electrical condition of the circuits serves to demonstrate the operating characteristics of relay 8. This momentary closure may, ior example, take H place throughoverfiow relays in a sender 1 an Ou circuit that may be connected during this period of operation in the selector, although it is immaterial as far as this invention is concerned in what manner and by what means this momentary circuit closure is established. It is sufficient to mention that relay 8 in accordance with this invention is designed to meet several changing conditions, in the circuit between the calling subscriber and the trunk, of which this momentary closure through a high resistance is the first. Succeeding changes will hereinafter be described. In any event, it is not desirable to have the relay operate in rest" rise to this first momentary circuit closure through one of its windings at present in order to prevent the premature operation of the lamp 104 at the toll operators position, which operation would indicate that the trunk is seized. However,

after the momentary closure in this circuit has passed, the circuit arrangements change so that a connection will be established, for example, through a polarized relay bridged across the tip and rin conductors. The resistance of this circuit in this instance will be considerably less than during t ie first momentary closure. The direction of the current in this circuit will be such that the polarized relay will not operate. The polarized relay has not been shown, but the circuit therefor through one winding of relay 8 may be as follows: battery and resistance through the upper inner armature and contact of relay 9, outer right hand armature and back Contact of relay 10, upper left hand winding of reeatin coil 11 u oer armature and back contact of relay 12, upper inner armature and back contact of relay 13 to the tip terminal and brush of switch S through the polarized relay, back through the ring brush and terminal of switch S and the trunk T, lower inner armatures and back contacts of relays 13 and 12, lower right hand winding of repeating coil 11, lower inner armature and back contact of relay 9, one winding of relay 8 through a resistance to ground.

When the selector has completed this connection (through the polarized relay) the re- 7 sistance conditions of the above circuit are such that relay 8 will operate. Relay 8 closes an obvious circuit for the operation of relay 15 as follows battery, winding of relay 15, outer right hand armature and back contact of relay 16, armature and front contact of relay 8 to ground. The operation of this relay closes a circuit to ground for the sleeve terminal connected to the switch S to prevent the selection of trunk T by other selectors. Another circuit closed by the operation of relay 15 is as follows: battery, winding of relay 18, outer right hand armature and back contact of relay 19 to ground at the middle lower armature of frontcontact of relay 15. Relay 18 operates and closes an obvious circuit for the operation of relay 20. Relay 2O closes battery and ground connections for the trunk T through the winding of relay 21, inner upper and lower armatures and front contact of relay 20, upper armature and inner low armature and front contacts of relay 15, right hand windings of repeating coil 11, tip and ring conductors'of trunk T, armatures and back contacts of relay 100 through the left hand windings of repeating coil 102 and the windings of-relay 101 in series. This circuit connection causes the operation of relay 101, but due to the lower high resistance winding ofrelay 101 relay 21 will not operate at this time. The operation of relay 101 closes an obvious circuit for relay 108, whici in turn closes an obvious circuit for the lighting of lamp 104C to indicate to the toll operator that a connection is desired over trunkT.

The operation of relay 20 also establishes a connection at its upper armature and front Contact from ringing source 23 which is thereby connected through the lower outer armature and back contact of relay 9 and the condenser and the ring conductor of the tr unit to the calling subscribers telephone to provide a ringing induction tone this tone indicating to the calling suoscriber that the connection has been completed to the toll operators position. The operation of relay 20 also closes an obvious circuit for the operation of relay 2 1 in an obvious circuit and this relay remains operated during the call under control of the alternating current responsive relay 25, as shown.

. The A operator answers this call by inserting plug 107 of an ordinary standard toll cord into jack 108. A. circuit is thereby established over the sleeve terminals for the operation of relay 105. Relay 105 in operating opens the circuit for lamp 104, which is thereby extinguished and closes a circuit at its left hand armature and from contact for the short-circuiting of the high resistance winding of relay 101. Suiiicient current will flow through the tip and ring conductors of trunk T to cause relay 21 to operate. relay 21 in operating closes an obvious circuit for the operation of relay 9. This relay in operating reverses the connections from the battery through the upper left hand winding of repeating coil 11 and from the ground through the winding of relay 8 for the subscribers line to efiect certain operations in the switches between the calling subscribers line and the trunk, which are of no importance in connection with this invention and V will not be described here, except to state that the above mentioned polarized relay will operate to establish a connection without encumbrances over the tip and ring conductors directly to the calling subscribers line from the trunk. Due to the operation of relay 9 nection through the associated resistance 6X- tends through one winding of relay 8 and the lower inner armature and front contact of relay 9, while the ground connection through an associated resistance extends through the other winding of relay 8 and the upper inner armature and front contact of relay 9. The" purpose of now connecting two windings of relay 8, in the circult to the calhng subscriber, is to'make relay 8 more sensitive to current interruptions such as will be produced by the calling subscrlb'er during superv1s1on, as Wlll hereinafter be described. Relay 8 is so constructed that a comparatively small resistance is added'by the inclusion of the second winding in the circuit, while the ampere turns will be materially increased. This re lay will therefore remain operated when the connection is extended to the calling subscribers line as hereinbefore described, even though the resistance of this connection 18 substantially increased over the resistance of the previous circuit throughthe polarized relay. Hence, thecharacteristics-of relay 8 are now changed from a non-operate characteristic for a high resistance circuit, which is the circuit first established on the momentary closure hereinbefore mentioned, to an operate characteristic for a second high rev sistance circuit, which calling subscriber. I

Relay 9 in operatlng closes a locking circuit for itself through its upper outer armatureand front contact to ground at the left hand armature and front contact of relay 18. It also opens the connection through the lowerouter armature and back contact and thereby removes the'tone for the calling subscriber.

' The operation of relay 21 also closes anobvious circuit, for the operation of relay 26. This relay in operating provides a substitute circuit for maintaining relay 15 operated by closing a connection through its left hand armature and front contact. The original circuit for the operation of relay 15 was closed through the outer right hand armature and back contact of relay 16 and the purpose of this substitute circuit will become apparcut as the description proceeds. As relay 26 operates, an obvious circuit is closed for the operation of relay 19. Thisrelay in operatingcloses an obvious circuit for the operation of relay 16. It also closes an i obvious circuit for the operation of relay 27.

' lay 27. The relays 19 and 16 provide circuits As relay 27 operated a substitute circuit is closed for maintaining relay 18 operated as it should be noted that on the operation; of relay 19 the original energizing circuit for relay 18 was'opened at theouter'right hand armature andback contact of this relay. lay 18 is slow to release $0.1 3 is maintained operated until the new circuit is closed by reto be described hereinafter for the control of is the circuit to the the return'of the coin deposited by the calling subscriber to enable him to make a call.

Relay 16 provides a locking circuit for itself through its inner right hand armature and front contact to ground at the left hand armature and front contact of relay 18. It-

also I establishes a connection to ground through its outer left hand armature and front contact and the outer left hand armature and front contact of relay 19 for opera*- ing relay 10. The circuit for relay 10 may be traced from battery to the left hand winding of this relay, outer left hand armature of relay 28, through the outer left hand armatures and front'contacts of relays 19 and 16 to ground. Another circuit closed by relay 16 is a ground connection through its inner left hand armature and front contact. This circuit is for the operation of relay 12 in case acalling subscriber'has to be rerung or recalled by the toll operator, as will hereinafter be described. The ground connection established through the outer left hand armature and front contact ofrelay 16 is also provided for the maintenance of relay 27 operated after relay 19 is released, which will take place at theend of the call as will hererelay 15 operated during the coin return pe-' riod" while the original connection to ground at the armature and front contact of relay 8 is opened. This connection will be established from the inner right hand armature and front contact of relay '10, the make-be I. 1

fore-break contact of relay 27, left hand armature and front contact of relay 26, winding of'relay 15 to battery. The circuits are now in condition for transmitting an impulse from the 110,-volt negative battery to return the coin deposited b the subscriber to enable him to call. When relay 10 operates, a circuit is closed for relay 30 as follows: battery, winding andinner left hand armature of relay 30 front con tactof relay 10'to ground at the armature and front contact of relay 31. Relay 31 operates, after relay 10 is operated, over an obvious circuit when the interrupter 32 closes a c0nnection to ground. The circuits for relays 30 and 31 are therefore alternately'opened' and closed under control of interrupter 32. Relay 10 also opens at its outer right handarmature and back contact the connection throughthe tip conductor to the calling subscribers line between the inner upper armature of relay 9 and the upper left hand winding of repeating coil 11. This 1s for the purpose of reducing ob ectionable clicksor surges pin the calling subscribers line on the subse quent operation of relay 13, as will hereinafter be described in connection with the return of the coin, at which time the circuit from battery and ground through relay 8 will be opened.

Returning now to the operation of relay 30, the first operation of this relay closes a circuit, for the operation of relay 33 as follows: battery, right handwinding of relay 33, left hand armature and front contact of relay 30, outer right hand armature and back contact of relay 34, make-before-break contact of relay to ground at the outer left hand armature and front contact of relay 16 through the outer left hand armature and front contact of relay 19. Relay 33 in operating extends a connection from the back con tact of the right hand armature of relay 30 through the outer right hand armature and front. contact of relay 33 to the winding of relay 34 and also establishes a connection from the inner right hand armature and front contact from the llO-volt negative battery to the front contacts of the inner upper and lower armatures of relay 13 preparatory to the transmission of the coin-return impulse to the magnet 5. Relay 33 provides a locking circuit for itself through its left hand winding from battery at its inner left hand armature and front contact to ground at the left hand armature and front contact of relay 16 and also closes an obvious circuit for the operation of relay 13. Relay 13 in operating opens the tip and ring conductors at the inner-upper and lower arinatures and back contacts of this relay and connects the -voltnegative battery to the tip and ring conductors to the calling subscribers line through magnet 5 to ground. The magnet is thereby operated in a direction to return the coin to the calling subscriber.

"This application of the coin return current remains for a long enough period to permit the magnet 5 to fully operate and the length of this period is determined by the interrupt er 32. "As relay 13 operates a circuit is completed through the right hand winding of relay 10 to ground to maintain it operated as long as relay 13 is operated, as the original energizing circuit for relay 10 will presently be opened. When the interrupter 32 opens the connection to ground, which may be within a period of one-half a second, relay 31 releases, causing the release of relay 30. Re-

' lay 30 in releasing causes the operation of relay 34 over the circuit hereinbefore traced to the right hand armature and back contact of relay 3,0 which now is extended to ground at the outer left hand armature and front contact of relay 16. Relay 34 in operating closes a locking circuit for itself from battery through its winding and outer right hand armature and front contact, make-before-break contacts of relay '35 to ground at relay 16. It also prepares an operating -cir-. cuit for relay 35 at its inner left hand armature and front contact, which will be completed when relay 33 later releases. A connect-ion to ground is also completed for maintaining relay 13 operated through its outer left hand armature and front contact to ground at relay 16 under control of the makebefore-break contacts of relay 35. Relay 13 is thereby held operated for an additional one-half second, that is, until interrupter 32 is again connected to ground. At the end of this second period the connection to ground is completed through the interrupter 32 to cause the operation of relays 31 and 30 for the second time. When relay 30 operates relay 33 releases, as it will be noted that the battery connected through its left hand winding for holding this relay operated it is now shunted through the right hand armature and front contact of relay 34 and right hand armature and front contact of relay 30 to ground at relay 16, the original energizing circuit for this relay being open at the outer right hand armature and back contact of relay 34. In releasing, relay 33 removes the coin-return battery from the magnet 5 by opening the connection through its inner right hand armature and front contact. This battery has therefore been connected to the magnet 5 for the period of one second.

Relay 33 in releasing opened the original operating circuit for relay 13, while the substitute circuit is maintained by relay 34. At the subsequent release of relays 31 and 30 through the removal of ground by the interrupter 32 after another one-half-second interval relay 35is operated from battery through its winding, inner left hand armature and back contact of relay 34, outer right hand armature and back contact of relay 33, right hand armature and back contact of relay 30 to ground at relay 16. Relay 35 in operating closes a locking circuit for itself through its outer right and armature and front contact to ground at relay 16 and transfers the circuit for maintaining relay 13 operated through its inner right hand armature and front contact, the outer left hand armature and front contact of relay 10, outer left hand armature and back contact of relay 28 to ground at relay 16. Relay 13 is therefore now controlled by relay 28 in place of relay 34 which is released by the operation of relay 35 by the opening of the make-before-break contacts of relay 35. Relay 34 in releasing opens the original energizing circuit for relay 35 and completes a circuit for relay 28 as follows: battery, winding of relay 28, outer left hand armature and front contact of relay 35, inner left hand armature and back contact of relay 34 through the connection hereinbefore traced from this armature to ground at relay 16. Relay 28 in operating closes a locking circuit for itself, under control of ground at relay 16, through its inner left hand armature and front contact and outer right hand armature and front contact of the relay 35. Relay 28 also closes the hereinbefore mentioned holding circuit for relay 27 at its outer right hand armature and front contact. Relay 28 now opens the holding circuit for relay 10 at its outer left hand armature and back contactand as the holding circuit for relay 13 also passes through this contact, relay 13 will release and this relay in turn causes the release of relay 10.

Relay 13 in releasing completesthe talking I connection from the calling subscriber through to the repeating coil 11 and when relay 10 releases the connection for the tip conductor is completed at the outer right hand armature and back contact of this relay I so that battery and ground are now again fed to the calling subscribers line. I

It Will be noted that this connection for opening and closing the tip conductor under control of relay 10 is such that it is opened beforerelay 13 is operated and closed after relay 13 is released, thus reducing the click that ordinarily would be transmitted to the subscribers telephone on the operation and release of relay 13. The circuit is opened I and closed by relay 10 between the battery and the repeating coil, it follows therefore, that no sudden discharges or charges will be felt in the line. In other words the left hand windings of the repeating coil will act as shock-absorbing or retarding meansduring interruptions ofthe circuit. Relay 10 in releasing opens the circuit for relay 31 to the interrupter 32, so that this relay 31 cannot again be operated. It also opens the s'upplementary holding circuit for relay 15, and this relay will now be held by ground at the armature and front contact of relay 8 which operates on the release of relay 10. With relays 35 and 28 operated and relays 34, 33, 30,

13, 10 and 31 released the coin-return circuit is prevented from again functioning until the calling subscriber and; the toll operator I i tablished for the reoperation of relay 8 to hold relay 15 operated. It should be noted that in have disconnected. I 1

The circuit is now completed to the toll operator for talking purposes, with the talking current applied for the calling subscriber at relay 8. The calling subscriber now gives the number of the wanted subscriber to the toll operator, who as is well known in the art establishes the connection to the wanted subscriber. Conversation between the calling subscriber and the called subscriber may then begin as soon as the calling subscriber has deposited the required coins in payment for the call.

The toll operator instructs the calling sub scriberto deposit the required amount and depositedcoins, although this circuit is also arranged for the collection of deposited coins at the end of the conversation in responseto the release of the connection by the subscriber and the toll operator. In regard to the return or collection of the coins in the [usual manner the procedure will be for the arrangements are made in this circuit in the usual manner for refunding or collecting the no part of this invention it will not be further described, except to say that the contact .42 will be controlled to close a connection to ground for the operation of relay 10; that the contact 41 actuated upwards or downwards to applyeither the 110-volt negative or positive current to the tip and ring conductors leading to the calling subscriber to operate the coin magnet 5 to refund or collect coins, and that contact 43 may be corre- I spondingly operated to apply coin return or collect tone to the toll operator. Rela 10 in operating provides a circuit for holdlng relay 15 operated when relay 8 is released on the operation of relay 13. Rela 13 is operated by relay 10 over a circuit from battery through the inner right hand armature and front contact of relay 35, outer left hand armature and front contact of relay 10 to ground at contact 42. The operation of relay 13 closes the circuit for holding relay 10 operated and also a circuit for the connection from contact 43 to apply the proper tone current to the toll operator. This connection may be traced from the particular tone source applied to contact 43 through the middle right hand armature and front contact of. relay28, upper outer armature and front contact of relay 13 to the tip conductor of the trunk T leading'to the toll operators position, The rparticular tone transmitted will indicate to the toll operator whether the coins have been refunded or collected. When the coin has been collected or refunded the ground' on contact 41 is removed and relay 13 is released. -When relay 13 releases, relay 10 is released and a connection is thereby essubscriber to the toll operator the subscriber will manipulate his switchhook and alternately cause the release and operation of relay '8 and this in turn causes the relay 15 to be alternately released and operated Relay 15 in releasing reverses battery and ground c0n-' nection through relay 101 and this relay in turn releases relay 10 3,which supphes curin this cord to be correspondingly actuated, as is well known in the art. "When relay is again operated this supervisory lamp is eX- tinguished so that for each manipulation of the switchhook the laiiipwill be lighted and the flashing of the lamp serves as a supervisory signal to the toll operator.

It will be noted that a condenser 40 is bridged across the tip and ring conductors between the windings of relay 21 and the siarinatures of relay 20. This is the regular condenser usually bridging the windings ot the repeating COll for talking purposes. It has been placed as indicated in order to prevent false operation of relay 21. Condenser -40is normally charged from battery and ground through the windings of relay 21, so that when relay 15 is alternately operated and released the charge on the condenser will practically remain the same and no surges ct current 'will pass through the windings of relay 21 under thesecircumstances. This relay is therefore prevented from operating falsely duringsiipei'vision. If this condenser had been connected as in ordinary circuits charges and discharges therethrough at the operation and release of relay 15 might have caused false operations ofielay 21, as the operating characteristics of relay 21 a re marginal. In order to avoid such possibilities the condenser 40 has been placed as shown.

When the calling subscriber originates a call in'the manner described above and the toll operator makes an effort to complete that call but is unsuccessful the toll operator will advise the subscriber to restore the receiver to the hook, stating that she will rering him when she is ready to complete the connection. When the connection is co ipleted she operates the ringing key in the toll cord and thus causes the alternating current relay 110 to operate. Relay 110 causes the operation of relay 100 and this relay in turn applies alternating current from the armature and fronttcontacts of this relay over trunk T to cause the operation'of the alternating current responsive relay 25. Relay in operating disconnects ground from the winding of relay 24, causing it to release. Relay 24 in releasing: closes an obvious circuit for the operation of relay 12. Relay 12 in operating establishes a holding circuit for relay 26 during the releaseperiod of relay 8, as relays 15 and 21 will be released ,at this time. Belay :12 appliesringing current from the source associated with the front contacts of, the upperand. lo wer inner arinatiires to the'calling 'subscribers :bell to rering the subscriber. YZhen the toll operator ceases to apply ring'-' mg currnh'ielays '110, '-1OO and 25' release,

1 causingthe'reoperation of relay 24, and the release of relay 12.

The talking connection is held established as long as the toll operators cord is connected to the trunk or the calling subscribers receiver remains off the hook. At the end of the conversation when the calling subscriber replaces the receiver on the hook, relay 8 is releasec, causing the release of relay 15. This opens the holding circuit for relay 26 and the current through the trunk T is reversed to re lease relay 101, which in turn releases relay 103. This relay in releasing applies battery and ground to the toll operators cord circuit to light thesupervisory lamp as a disconnect signal. WVhen'the toll operator removes plug 107 from ack 108, relay 21 releases and this relay in turn releases relay 26.

When relay'26 releases and in case the coins deposited by the calling subscriber have not been'collected manually as hereinbefore described the coin collect magnet 5 will now be actuated to collect the coins automatically.

The release of relay 26 causes the release of relay 19 and also opens the operating path for relay 15, so that this relay cannot be again operated as long as this connect-ion remains. The release of relay 19 opens the holding circuit for relays and 28 and the operating circuit from relay 27. Relays 35 and 28 release immediately but relay 27 is held operated until after the release of relay 28. Relay 19 also opens the'operating circuit for relay 16 and this relay is now under control of the holding circuit established through the left" hand armature and front contact of relay 18. Relay 35 in releasing applies ground through the resistance associated with the contacts for the inner upper and'lower armatures of. relay 13 to serve as adischarge absorbing circuit, as

Will hereinafter appear. Relay 35- also opens the original operating circuit for relay 28 at its outer left hand armature andfront contact. Another circuit opened by the release of relay 35 is that through its inner left hand armature and front contact to the manual coin collect and refund circuit arrangement controlled through contact 42, so that the automatic'coin collection cannot be interfered with by manual coin operations. Relay 28 in releasing opens the holding circuitfor relay 27. Relay 27 is held operated in'this manner to insure that relays 28 and 35 are released on the release of relay 19.

Relay 28 in releasing restores the operating circuit for relay 10, so that this relay will now lay 18, but this relay is held operated through a substitute path established through the inner right hand armature and back contact of relay 27 to ground at the inner right hand armature and front cont-act of relay 10, so that the relay 18 will remain operated until the coin collect circuits have functioned Re lay 27 in releasing substitutes the positive llO-volt coin. collecting currentconnection for the l10-volt negative coin return current scribed. Relays 33, 34, 35, 13 and 28 will now function as hereinbefore described, except that the coin collect current from the positive source at the outer left hand armature and back contact of relay 27 is sent to the subscribers station instead of the coin return current. To review these operations briefly, the first operation of relay 30 causes relay 33 to operate. Relay 33 in turn prepares the circuit for relay 34; extends the connection from the 110-volt positive coin collect battery to the contacts of relay 13; provides a locking circuit for itself whichi'n this case is extended through the outer right hand armature and back contact of relay 27 to ground at relay 16, and closes the circuit for the operation of relay l3.

Relay 13 applies 110-volt positive current to magnet 5 to operate it to collect the coins. When the interrupter 32 opens the circuit for relay 01 at the end of the first half-second period, relays 31 and 30 release, causing the operation of relay 34, which in turn establishes a locking circuit for itself, prepares a circuit for relay 35, and provides aholding' circuit for relay 13 under control of relay 10. When the interrupter 32 again completes a connection to ground relays 31 and 30 are operated. Relay 33 is thereby released, causing the 110-volt positive battery connection to be opened to release magnet 5. At the subsequent release of relays 31 and 30 relay 35 operates to close a locking circuit for itself; to transfer the circuit of relay 13 to be under the control of relay 10 and to release relay 34. Relay 34 in releasing opens the original circuit for relay 35 and causes relay 28 to operate. Relays 35 and 28 are now under control of relay 16. Relay 28 causes the release of relay 13, which in turn causes the release of relay 10. With relays 35 and 28 operated and relay 10 released the holding ground for relay 18 is removed, causing it to release. Relay 18 in releasing removes theground from the sleeve circuit to the calling subscriber for switch S, causing the switches S and LF to release the calling subscribers line from trunk T. Relay 18 also causes the release ofrelays 9, 16, and 20. ,The release of relay 16 in turn releases relays 3.5 and 28 and the circuits of the trunk T are therefore now intheir normal condition. It should therefore be noted that the arrangements of the circuit of trunk T are such that in case the toll operator neglects to collect the coins deposited by the calling subscriber in pay-- ment for the call these circuits functionautomatically to operate magnet 5 to collect deposited coins. It should be understood, however, that the equipment for collecting coins manually by a toll operator may be dispensed with as the circuits of trunk T will always function to automatically collect coins before the connection is finally released. I,

The above described circuit arrangements should be considered merely as illustrative of oneembodnnent ofthe invention and 1t should be understoodjthat many other arrangements may be employed without de parting from the spirit of the invention.

What is claimed is: r V 1. In a telephone system, two stations, a

coin collect and refund device associated with one of said stations, means for establishing a connection between said stations, means responsive to theestabhshmg of'said connectionfor actuating said device to refund coins deposited therein, and means responsiveto the releaseof said connection for actuating said device to collect coins deposited therein.

2. In a telephone system, a calling subscribers line, a coin collect and refund device associated therewith, a trunk, means for conn'ecting said line and device to said trunk at one end thereof under control of the calling subscriber an o erators cord circuit for association with said trunk at the opposite end thereof, and means responsiveto the release of anjestabli-shed connection bythe calling subscriber and to the removal of the cord from the trunk for actuating said device to collect coins deposited therein. Y r

3.In a telephone system, a calling sub-- scribers line, a coincollect and refund device assoc ated therewith, a trunk, means forconnecting said line and device to said trunk at one end thereof under control of the calling subscriber, an operators cordcircuit for association with said trunk atthe opposite end 7 thereof, a sourceof current, an interrupter, and means responsive to the release of an established connection. by the calling subscriber andremoval of the cord from the trunk forapplying current from said source to said device under control of said interrupter to actuate said device to collect coins deposited therein; I I y 4. In a-telephone system, a line, a source of current, a first relay, a second current reversing relay, the tip and ring conductorsof said line being connected from the source of current throughthe windings ofthe first re- M. loJ

'visory relay having two windings,

ing coil, a source of current, a first relay, a

second current reversing relay, the tip and ring conductors of said line being connected respectively through windings of said rep-eating, coil, contacts of the current reversing relay and windings of the first relay to the source of current, and a condenser bridging said conductors and placed between the contacts of the current reversing relay and the windings of the first relay.

6. Ina telephone system, a line, a super-' and normally having one winding connected between ground and the incoming end of one of the conductors in said line, and means responsive to the seizure of the outgoing end of said line for connecting the other winding of said relay between battery and the incoming end of the other conductor of said line.

7. Ina telephone system, a line, a relay associated with one end of the line in one manner'to be non-responsive to currents of a certain value, and means responsive to the seizure of the other end of said line for associating said relay in another manner with said line to be responsive to currents of sub stantially the same value.

8. In a telephone system, a line, a source of current, a supervisory relay associated with the incoming end of said line and connected to said source of current in one manner to have certain marginal operating characteristics, and means responsive to the seizure of the outgoing end of said line for connecting said relay to said source in a different manner for decreasing the marginal characteristics of said relay by increasing the ampere turns thereon without materially increasing the resistance'.

9. In'a telephone system, a line, a source of current, a repeating coil connected between the source of current and the line, means for opening the connection between the repeating coil and the source of current for thereafter opening'and closing the connection between the line and the repeating coil and finally for closing the first mentioned conneetion.

10. In a telephone system, a line,a source of current therefor, arepeating coil connected between the source of current and the line, means for interrupting the connnection between the line and the repeating coil, and means responsive to said interrupting means for opening' the connection between the repeating coil and the source of current beforesaid interruptions take place and closing it after the interruptions have ceased.

11. In a telephone system two stations, a coin'collect and refund device associated with one of said stations, means for establishingconnection between said stations, a relay actuated in response to the establishing of said connection, means responsive to the actuation of said relay for actuating said device to refund coins deposited therein, means responsive to the release of said connection for releasing said relay, and means responsive to'the release of said relay for actuating said device to collect coins deposited therein.

12. In a telephone system two stations, a

coin collect and refund device associated with one station, means for establishing a connection between said stations, two relays actuated in response to the establishing of said connection and a third relay actuated in response to the actuation of one of the first mentioned relays, means responsive to the actuation of said third relay for actuating said device to refund coins deposited therein, means responsive to the release of the connection from one station for releasing one of said first mentioned relays and responsive to the release of the connection from the other station for releasing the other of said first mentioned relays to cause the release of the third relay, and means responsive to the release of said third relay for actuating said device to collect coins'deposited therein.

In witness whereof, I hereunto subscribe my name this 9th day of May, 1928.

THOMAS V. CURLEY.

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