US2192025A - Telephone system - Google Patents

Description

Feb. 27, 1940. J, usc 2,192,025

TELEPHONE SYSTEM Filed June 17, 1938 9 Sheets-Sheet 1 A T TOR/V5 V QNN Feb. 27, 1940.

O 2. I INVENTOR By AJBUSCH A. J. BUSCH TELEPHONE SYSTEM File d June 17. 1938 Feb. 21, 1940..

9 Sheets-Sheet 3 INVENTOR AJBUSCH BY A T TORNE V Feb. 27, 1940. A. J. BUSCH TELEPHONE SYSTEM 9 Sheets-Sheet 4 Filed June 17. 1938 lNl/ENTOR A. J. BUSCH By W A 7' TORNE V Feb. 27, 1940. A. J. BUSCH 2,192,025

TELEPHONE SYSTEM Filed June 17, 19:53 9'SheetsSheet s //v l/EA/ TOR By AJ. BUSCH A T TORNE V Feb. 27, 1940.

A. J. BUSCH 2,192,025

TELEPHONE SYSTEM Filed June 17, 1938 9 Sheets-Sheet 6 FIG. 6

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wwww ATTORNEY Feb. 27, 1940. A. J. BUSCH 2,192,025

TELEPHONE SYSTEM Filed June 17. 1938 9 Sheets-Sheet '7 //v ve/v TOR B y AJ. BUSCH WWW ATTORNEY Feb. 27,1940. A. J. BUSCH TELEPHONE SYSTEM Filad June 17, 1938 9 Sheets-Sheet 8 VI mm T5 0 NU q .T we w r W H W. A

NON DR W90 90 QQN 0.0

A. J. BUSCH mmarnoufi SYSTEM Imam Jun'e'17, 1938 9 Shoetg-Sheet 9 lA/VENTOR AJ. BUS CH WSW'JM ATTORNEY Patented Feb. 27, 1940 PATENT OFFICE TELEPHONE SYSTEM Aloysius J. Busch, Madison, N. J assignor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application June 1'7, 1938, Serial No. 214,348

10 Claims.

This invention relates to telephone "systems and particularly to systems in which automatic.

switching equipment is employed for establishing connections.

It has been the practice heretofore in automatic telephone systems to provide common controlling mechanisms at the central officefor the purpose of collecting at periodic intervals during a telephone conversation the coins that are deposited by the calling party at a coin subrstation. Since these controlling mechanisms are common to a number of trunk circuits in the central ofiice, and since their service is required only for a short interval of time while the deposited coin is being collected,.the usual arrangement is to connect an 'idle one of these mechanisms to any one of the trunks having a call thereon which has progressed to the point where the deposited. coin should be collected and thereafter to restore the mechanism to normal in order that it may be taken in use by any other trunk having a call thereon that requires similar treatment. In addition to these periodic coin collecting operations it is also the practice in systems of this kind to make tests of the calling coinline at regular intervals to determine that the calling patron has deposited a coin entitling him to another interval of conversation. In the past, the'testing devices'for testing the calling line to determine whether the coin has been deposited have been associated individually with the trunk circuits over which the conversational connections are established. Moreover, it has been necessary to provide individual connecting circuits, such as operators jacks, for each of the trunk. circuits in order that a monitoring operator could make connection with any one of the trunks having a call thereon in the: event that the testing mechanism discovers that the calling patron has failed to deposit a coin for the next periodic interval of conversation.

The objects of the present invention are to simplify the equipment used in these systems by combining in a single controlling mechanism the function of testing for a depositedcoin and the function of disposing of the coin; to obtain a more reliable test for the presence of the coins deposited by the calling patron;v to simplify the equipment necessary for monitoring on the established connections; and to secure other improvements in systems of this general character.

A feature of the present invention is a system in which a plurality of coin-control mechanisms are provided in common to the conversational trunks in the central office, and in which any particular one of the trunks having a call thereon, establishedfrom a coin substation, seizes an idle one of the control mechanisms for a brief interval near the end of each overtime period of conversation and again seizes an idle one of these mechanisms for a brief interval at the end of each such overtime period. When the control mechanism is connected to the trunk near the expiration of the conversational period,

it proceeds to collect the coin that was previously deposited at the calling substation in payment for the: conversational period. At this time the control mechanism also transmits a warning tone to the calling party, advising him that the conversational period is about to expire and that he should deposit a new coin if he wishes to continue. I On its subsequent connection to the conversational circuit, namely, at the end of the full conversational period, the control mechanism makes a test of the calling line to determine whether the calling party has deposited a new coin for the next period. If the mechanism fails to find'the coin when it attempts to collect on itsfirst association with the circuit monitoring operator is" signaled and shemakes connection with the calling line, by way of a deposits the new coin or advises the operator that he has already done so, she withdraws from the connection.

Another feature of the invention is an arrangement whereby the control mechanism makes a retest of the calling line for the presence of a coin after the monitoring operator withdraws from the connection following her request to the calling party to deposit a new coin for the next conversational period.

the mechanism is disconnected and returns to common use; but, if the retest shows no coin is present, the mechanism again signals the moni toring operator, and she returns to the con- If on retest the control mechanism finds that a coin has been deposited,

near the end of the conversational period, the

While the system .disclosed is not limited to the nection and requests the calling party to deposit the coin. And on each withdrawal of the monitoring operator the control mechanism tests the line for the presence of the coin and will not retire from the connection until this test has been satisfied.

A further feature of the invention is the provision whereby the monitoring operator obtains connection to any calling coin line by means of connecting circuits, such as jacks, which are individual to the common control mechanisms. The control mechanism is always associated with the individual subscribers line at the time the monitoring operators service is required, and by giving her access to the lines by way of these common mechanisms rather than by way of connecting circuits individualto the central oflice trunks, a considerable economy is effected in the equipment required, and a concentration of the operators connecting circuits is also obtained.

These and other features of the invention will be discussed more fully in detail in the following description and will also be set forth in the appended claims.

Referring to the drawings which accompany the detailed specification:

Fig. 1 shows a district junctor circuit arranged to function with a coini-control circuit and connected conventionally with a coin-box subscriber station by a line link and group control circuit Fig. 5 is an abridged form of a link and control circuit to illustrate means whereby a connection between the district junctor of Fig. 1 and the coin-control circuit of Figs. 6, 7 and 8 may be established;

Figs. 6, '7 and 8 placed together in order from left to right illustrate the coin-control circuit; arranged according to this invention;

Fig. 9 illustrates in an abbreviated schematic manner the connection of the district junctor of Fig. 1 through a subscriber sender link and control circuit to a subscriber sender circuit, conventionally represented by a box; and

Fig. 10 is a block diagram showing the manner in which the several figures of the drawings, should be arranged to show a complete system.

General description The invention is illustrated in an automatic telephone system in which automatic switches of the cross-bar type are used as the medium for extending connections from subscribers lines over trunks to other subscribers lines. These cross-bar switching mechanisms are controlled by register senders at the central office, which receive the designations from the calling subscribers dials, and by decoder markers. These markers are connectable to the senders for receiving information from the senders and are connectable to the proper switch frames for the purpose of testing the outgoing trunks and for testing the connecting links and for operating the magnets of the cross-bar switches to establish the connections.

use of cross-bar switches of any particular type, reference may be had to the patent to Reynolds 2,021,329 of November 19, 1935, for an understanding of the construction and operation of a switch suitable for use in such systems. Because .of. the complicatednature of these systems, and

will be understood that the circuits and equip- Y ment so referred to are already known and in particular reference is here made to the following for a detailed disclosure of operations and equipment referred to herein but not specifically dis- 14, 1937; and Carpenter application Serial No. 214,356, filed June 17, 1938.

The subscribers lines, such as line I00, are

connected to verticals of the primary cross-barswitches indicated conventionally by theappa-- ratus in the box I01 and thence extended through secondary switches, suchas switch I02, to district junctor circuits; The'connections to the district junctor circuits are effected by means of a line link and group control circuit and a subscriber sender link and control circuit. The circuit'details (not shown) whereby these connections ,to'

the district junctor circuits are effected may be the same as in Carpenter Patent 2,093,117, and

Carpenter application Serial No. 214,356, above,

mentioned. I

When the connection to the district junctor, which is one of a group of similar junctors, not

shown, is established as above outlined, the sube scriber sender 900, througha link circuit represented in abbreviated form by primary and sec-5 ondary cross-bar switches 90! and 902, functions in association with a marker circuit, indicated by,

a box 200, to establish connection to an outgoing trunk 206, in accordance with the office code dialed at calling station 103 and recorded by sender, 900. through district framejcross-bar switches 20! and 202 and office frame switches 203 and 204.

When the outgoing trunk206 is thus seized a connection is established through an incoming,

link and connector circuit consisting of cross-bar switches 300 and 30 l, and line link circuit consisting of cross-bar switches 302 and 303, to thelineof the called subscriber station 304. After the subscriber of station 304 answers, this condition is registered in the district junctor of Fig. 1.

The district junctor of Fig. 1 has common ac cess to a group ofcoin-control circuits, one of which is shown by Figs. 6, '7 and 8. nection to a selected coin-control circuit is made by means of the link and control circuit of Fig. 5, which consists essentially of primaryand secondary cross-bar switches 500 and 50]. This link and the associated control circuit, whereby a calling district junctor is connected to an. idle coin control circuit, are not shown in full detail since they are well known and may be essensentially the same as those shown in Carpenter Patent 2,093,117, and Carpenter application Serial No. 214,356, above mentioned.

This connection. is established. Y

The con- The district junctor circuit of Fig. l is arranged 2o closed: Carpenter Patent 2,093,117 of September 5 lay I12 to ground on conductor H6.

after a completed connection, immediately after the calling party'has disconnected; (b) to collect a coin-during conversation at the end of a predetermined interval; (0) to return a coin after an incompleted connection immediately after the calling party disconnects or for a free call; (0K) to test for the presence of an additional coin at the beginning of an overtime period, and, in

case no coin is found, to summon an operator for overtime monitoring on the connection. In the case of condition (a), before mentioned, the coin control circuit makes a test to determine the presence or non-presence of a coin in the coin box I04 and to determine whether or not the coin box "14 has been properly cleared after the application of coin-collect current. For either of these conditions lamp 8% is flashed to inform an operator of the failure to collect the coin. For condition (1)), should the coin-control circuit fail to find a coin, lamp 8M is immediately flashed to inform the operator of this condition. For con dition (c), lamp 880 is lighted steadily if the coin box is not properly cleared after the application of coin return current. For condition (d), the operator is summoned by the steady lighting of lamp 8M, if the test indicates no coin is present.

Detailed description of operation The operation of the system will now be described in detail, and for this purpose let it be assumed that the calling party or" station H33 initiates a call by depositing a coin I05 in coin box I04 and by actuating the telephone switch of station I03. A circuit is thereby closed for operating line relay Iilt, whichcircuit may be traced from battery through the winding of relay I06, lowermost contacts of cross-bar switch hold magnet Hll, over ring conductor of line Iiiil, through the switch contacts of station I03 and thewind ing and associated contacts I68 of coin collector magnet I68 to ground Hi9. Line relay I06 functions in cooperation with the line link and group control circuit of Fig. 1 and the subscriber sender link and control and subscriber sender circuits of Fig. 9 to effect the selection of an idle district junctor circuit, and an idle line link extending thereto. The idle condition of the district junctor circuit is indicated by the presence of battery on busy test lead I I3. The circuit details, whereby this is accomplished are shown by the aforesaid patent application of W. 'W. Carpenter, Serial No. 214,356, filed June 1'7, 1938. l

The selection before stated having been made, cross-bar switch contacts of the primary switch NH, and of the secondary switch Hi2, are closed, extending the conductors of line Mil to conductors I I0 and l I I, which terminate respectively on the upper outermost, and lower innermost break contacts of relay H2, through which contacts connection is made over conductors IM and H5,

through the cross-bar switch contacts of the agramatically by boxes till and SE32, to subscriber sender Silil. Dial tone is now furnished over these conductors as an indication to the party of station I03 that dialing may now bestarted. Ground is also connected at this time by the hold magnet 994 of the subscriber sender link and control circuit to conductor H6 and thereby is operated relay H1. The operating circuit may betraced from battery through the winding of relay Ill, upper next-to-innermcst break contacts of re- Relay H1 in operating performsno useful function at this time, except to disconnect busy test battery H8 from test conductor i I3, this circuit being traced from battery H8, through resistance H9, upper outermost break contacts of relays I20 and IZI, and lower outer break contacts of relay Ill to conductor H3. This disconnection of battery H6 makes the district junctor test busy to the sender link and control circuit on subsequent calls. Hold magnet 903 of the sender link and control circuit also connects ground to conductor -22, which is extended through upper outer break contacts of relay I23 and resistance I24 to sleeve conductor I25, thereby supplying aholding ground for the line link hold magnets IN and M6, while thesender bill] is connected to the district junctor circuit.

While the connection is being established from the calling line Hill to thesender circuit 990 the subscriber sender link and control circuit of Fig. 9 is momentarily connected to sender circuit liiil and during this momentary interval sender circuit 968 is furnished with the class of service information of line I09) and also is informed of the number of the district link and connector frarneassociated with the district junctor circuit to which sender $00 is connected. The line link and group control circuit and the subscriber sender link and control circuit are used only momentarily to connect line Itll to an idle district junctor circuit and a subscriber sender circuit and are then released to serve other calls but the connections through the cross-bar switches IiII, I02, Bill and 902 which these circuits' have established are held by the subscriber sender circuit Bill! under control of the calling subscriber. After the ofiice code has been dialed, sender 900 connects to "the originating marker circuit 206, by means of a connector circuit 905, over a group of conductors represented by the broken line 906. The sender circuit Bill! registers in the marker circuit 2% the ofiice code, the class of service information of the calling line IM, and the number of the district link and connector frame serving the district junctor circuit involved in the call. The marker 2M then furnishes the sender 9% with the necessary information which it requires to control the progress of the call. Marker 200 then selects an office link and connector frame on which the desired trunk 2%, leading to the called destination, appears, connects itself thereto and also to the district link and connector frame that is associated with the district junctor circuit involved in the call. After this has been successfully accomplished, marker 26!) connects ground to a conductor which is extended through connector 9535, sender 9M. and the sender link circuit consisting of switches and 982 to conductor I13, thereby operating district ,iunctor relay IZ'I'. Relay I21 in operating connects ground with its upper next-to-innermcst contacts to conductor I28, thereby operating select magnet 205 of the primary switch 2!!! of the district link and connector frame serving the district junctor of Fig. 1, and connects ground with its lower inner contacts to conductor 83L thereby operating relay '207, which is common to a group of district junctors served by the primary switch represented by the box 28!. The operation of relay 2E3! extends conductors E29, I383, I3I. I32 and 209 through contacts of a marker connector relay to the marker circuit 211!) selected for handling the call being established. This connector relay which is not shown, being indicated only by broken lines, is individualto the marker circuit 208 and is operated each time that marker 26!) is selected for service in establishing a connection to the district frame represented by Fig. 2. Conductor I29 is used by marker tilt to determine when the primary switch 25H has operated from ground supplied by the marker over conductor 269. This is effected, by the extension of the aforesaid ground through lowermost primary switch contacts associated with magnet 2&8, over conductor I'M, through upper outermost make contacts of relay I21, over conductor I29, through upper neXt-to-outermost make contacts of relay ZIJI, and contacts of the aforesaid marker connector relay, not shown, to

marker 2%. 7 Conductor I30 is grounded by marker ilt through upper next-to-innermost contacts of relay 201, to operate relay I33, through upper innermost contacts of relay I27, for calls to an operator. Conductor ii is used by the marker Zi'idto hold relay IZ'I operated, through its lower innermost contacts, until the marker 2% releases, as hereinafter described, and conductor I32 through lower outermost make contacts of relay I2? to give the sender 9% a trouble release signal if a trouble condition has been encountered by marker 2% in establishing the connection. If relay I33 is operated it will look through its lower innermost make contacts to ground supplied by sender 900 over conductor Marker Zllil now establishes the connection through the district and omce switches to trunk 286. Select magnet 2H. of secondary district switch 202 is operated by ground on the lower outer contacts of relay ZII'I. Select magnet 252 of the primary office switch 203 is operated by ground on the upper contacts of relay 2I3,'and select magnet 2M of the secondary switch by ground on the contacts of relay M5, both of which relays are operated by marker mill. The

- link between the secondary district primary ofllce switches is established when relay BIS is operated by marker 20!] and operates hold ma nets 2 I I and 2|! from ground over conductor 236. The link between the primary and secondary switches of the office frame is completed, when. hold magnet H8 is operated from ground in the marker through lower contacts of relay 2L3.

After the marker Hill has established connection with the trunk 286 as before described, it releases relay IEI by removing ground from the winding of relay 2B1. Relay IZ'I releases and closes the sleeve conductor l'l l through to ground on the upper inner make contacts of relay Ill. Marker 20!] tests for this ground and if it finds this ground disconnects. Relay II'I was operated over conductor Ilfi when the sender link and control circuit connected sender 905! to the district junctor of Fig. 1. Relay I21 in releasing opens conductors I28, I29, I3Il, I3I and I32 to the district link and connector circuit and con nects conductor I with its lower outermost break contacts, to the winding of relay I36 so that the sender can operate this relay later.

When the marker has established connection to the outgoing trunk 286, sender 9% then cooperates with the incoming apparatus of Fig. 3 to complete the call to the line of the called station 3%. In connection with this incoming paratus a terminating sender and terminating marker, not shown by Fig. 3, are provided. As soon as the connection to trunk 2% is established, a circuit is closed for operating relay 3%, through break contacts of relay 3%, over the established connection and over conductors I46 and M5 extending into the subscriber sender 955. The

operationof relay 305 at first closes a start leads not shown, that causes the terminating sender aforesaid to be connected. After this the t.ermi-- nating sender receives from sender 900 the necessary information for completing in cooperation with the aforesaid terminating marker the con-r nection to the line of the called station 306.

After sender 980 has completed its functions in establishing the connection, as above outlined, it connects ground to conductor I35 to operate relay I36 through lower outermost'break contacts of relay I27. When relay I36 operates it;

locks under control of relay I12 in a circuit from.

battery through the winding of relay I36, upper innermost break contacts of relay I12 to ground on the upper next-to-innermost contacts of relay I36. Relay I36 in operating closes the transmission circuit to station I83. This may be traced from conductor IIII, through upper outermost break contacts of relay I I2, upper next-to-outer.

most makecontacts of relay I36, upper next-tooutermost break contacts of relay I72, condenser I37, lower middle make contacts ofrelay I36; and lower outermost break contacts of relay" I12 to conductor I38; also from conductor I I I,

through lower innermost break contacts of relay IIZ, lower next-to-innermost make contacts of I00. For this purpose ground is supplied through the left winding of relay MI, upper neXt-to-innermost break contacts of relay M2 to junction polnt I 42; battery is supplied through the right winding of relay MI, lower next-to-innermost break contacts of relay H2 to junction point I43.

After sender circuit 9% has completed its func 'tions and has operated relay I36 over conductor I35 as before stated, it releases. This causes the cross-bar switches 9M and 9M of the sender link circuit of Fig. 9 to be released which opens the connection of conductors H4, H5, I34, I22, I13, I44, I45 and I35. The established connection is now placed under control of the district junctor circuit of Fig. 1. The connection is held under control of relay III which remains operated provided the, calling subscriber station I03 is still connected to the line causing the operation of relay MI over the line loop. Relay I4! operated holds relay II I operated in a circuit that is traced from ground on the upper outermost contacts of relay II'I, operated contacts of relay I M upper neXt-to-innermost break contacts of relay I'IZ, through winding of relay II! to battery.

After the connection to the trunk 206 has been 3 established, a-circuit is completed for operating the bridged impedance relay 365 of the incoming trunk circuit over the loop extending to the calling district junctor of Fig. 1. This may be traced through the windings of relay 365, upper and lower break contacts of the reversing relay 3%,

over trunk 2%, contacts of the cross-bar switches EM, 293, 262, 2M, over conductors I49 and I38, outermost break contacts of relay I12, upper outermost make contacts, and lower middle make contacts of relay I36, winding of polarized relay Its and retardation coil Ml and lower inner operated make contacts of relay III. Relay 3B5,

operates in this circuit, but polarlzed relay 146 does not operate at this time.

When the called subscriber of station 304 answers, a circuit is closed for operating the bridged impedance relay 301, which maybe traced. from battery and ground through the windings of relay 301 over the tip and ring conductors and contacts of the cross-bar switches 300 and SM of the incoming link circuit and of the cross-bar switches 302 and 303 of the line link circuit to the line leading to the called station 304. Relay 301' in operating closes an obvious circuit for operating the reversing relay 306, which in operating reverses battery and ground over trunk 206, thereby causing polarized relay I46 of the district junctor circuit of Fig. 1 to operate. Re-' lay I46 in operating connects ground to the armature of interrupter I48, through the upper innermost break contacts'of relay I33. When interrupter I48 connects ground to the'lower winding of relay I23, relay I23 operates and locks to the operating ground through its lower inner make contacts. After a convenient predetermined short interval, saytwo seconds, interrupter I48'closes a circuit for operating a charge relay I49, through a circuit from battery through the winding of relay I49, lower outermost break contacts of relays H2 and I50, off-normal contacts -I69 of interrupter cam I5I, upper outermost outermost break contacts of relay IIZ to ground on the lower outermost operatedcontacts of relay I 49; (1)) partially prepares a path for starting an automatic release circuit, to be hereinafter described by connecting to interrupter I54, with its upper outermost make contacts the break contacts of the polarized relay I46; (0) partially prepares a path, by closing its upper next-toinnermost contacts, for operating relay I12 by connecting the winding of relay I12 to the upper contacts of relay I55; (d) provides an auxiliary holding circuit for relay I36 which is required when the automatic. release circuit arrangement releases the district junctor circuit by operating relay I12, this holding circuit extending from battery through the winding of relay I36, lower outermost break contacts of relay I21 to ground on the upper middle contacts of relay I49; (6) partially closes, with its upperv innermost make contacts, the circuit for operating message register I56; (1) opens with its lower innermost break contacts the tip conductor of the trunk towardy relay I12 so the trunk circuit will start to release when relay I12 is operated by the automatic release circuit; (9) connects ground, with its lower, next-to-innermost make contacts to conductor I51 to be used later by the coin control circuit as a signal to collect the coin deposited in the coin box I04 associated with the station I03, (h) closes a circuit for operating the'magnet I58 tostarttiming the call. This circuit is traced from battery through the winding of magnet I58, lower next-to-oute'rmost make contacts of relay I49, upper innermost break conwhen relay II1 releases.

tacts of "relay H2 "to ground on the upper outer make contacts of relay II1.

It is now in order to describe the operation whereby a coin deposited in coinbox I04 is collected or returned; or an operator is summoned, to monitor on an overtime call,'or in response to a failure of the calling party to deposit a coin or in response to a stuck coincondition;

' The collection of the deposited coin due to the disconnection of the callingparty, prior-to the expiration of the time limit will now be discussed. When the calling party-at station I03 disconnects, relay MI releases, which. in turn releases relay lI1. Relay I46 releases releasing relay i253 when the called party disconnects or When relay II1 releases it operates relay I20 in a circuittraced from ground through the lower winding of relay S20, upper middle make contacts of relay lilt, upper neXt-to-cutermost contacts of charge relay I SQ, lower outermost break contacts of relay I2I, lowerouter break contacts of relay II I, upper outermost break contacts of relay I2 I, lower next-to outermost' make contacts of relay I35, upper innermost contacts of relay EZI to battery through resistance I59. (a) locks through its lower innermost contacts and upper innermost break contacts of relay l2} 1 to battery through resistance E59; (b) connects ground with its lower middle contacts, through lower middle break contacts of relay I2! to start Relay I20 operated furnishes "a holding circuit for relay I36, this holding circuit being traced from ground on the lower outermost make contacts of relay 520,

through upper outermost break contacts of re-, lay I23, and upper innermost make contacts and winding of relay I36 to battery. 6

' When ground. is connected to start conductor I60, as aforesaid, the link and control circuit of Fig. 5 functions and causes a coin control circuit, which is shown by Figs. 6, '1 and 8, tobe connected. Fig. 5. is not apart of this invention, is shown only in skeleton form and only to facilitate the description of this invention. Link and control circuits of the type required for use with this invention are so designed that, when summoned for service, an idle link from a group of links is selected, and the selected link then selects an idle coin-control circuit from a group.

of coin-control circuits. With these selections made, the required connection between coin-control circuit and district junctor is next established. When ground is connected to start conductor I60, relay 502 operates throughits upper winding and looks through its lower winding to ground on the lowermost contacts of relay Ground on the upper outer contacts of relay 502 operates primary select magnet 504 of crossbar switch 500, and ground on the upper inner contacts operates relay 505, through upper break contacts of relay 506. Relay 505 looks through its lower inner contacts to ground on the lower inner break contactsof relay 503, with its upper inner contacts. it operates select magnet 501 of secondary cross-bar switch 50E, and with its upper outer contacts relay 50B. Relay 508 connects ground to the multipled windings of primary hold magnets 509 and 540, and secondary hold magnets 5! I and 5I2 and these magnets operate causing cross-bar switches 500 and 5M to control conductors 5I5, 5M, 5, 525', 5I5, SIS; M8 and 525, respectively.

When the link and control circuit of Fig. 5 establishes a connection, as before described, re-

' lay 505 connects ground with its lower outer contacts to conductor 522, thereby operating relay 554. Relay 554 operated (a) connects the winding of relay 555, with its upper outermost front contacts to conductor 005, so that this relay may operate if ground is connected to this conductor by a district junctor that requires overtime monitoring service, as will be hereinafter described; (b) connects together, with its upper next-toinnermost contacts conductors 52I and 526, thereby operating relay 521 from the operating ground supplied by relay 503 through switch contacts 528; (c) connects the upper winding of relay 656, through its upper neXt-to-outermost make contacts, over conductor 520 to the Winding of release relay 503; (d) partially prepares,'withits lower 'next-to-outermost make contacts, a circuit for operating relay 551 over conductor 524; (e) connects with its lower outermost make contacts, the winding of relay 558 to conductor 525, so that this relay may operate for coin-return service as will be hereinafter. described.

Assuming that ground has been connected to conductor 4 57 by the action of the district junctor circuit of Fig. has before described, thereby establishing the condition for coin collection, relay 659 operates in a circuit from battery through its I winding, lower middle break contacts of relay 051,

lower outermost break contacts of relay 050, over conductor 5H, through associated contacts 10f cross-bar switches 583i and 500 to said ground on conductor I51. Relay 559 in operating, operates relay I in a circuit from ground on the upper middle make contacts of relay 059, through lower innermost break contacts of relay 560 to battery through the winding of relay 06 I. Relay Gtl in operating, connects ground to conductor 5! in a circuit traced from ground on the upper inner make contacts of relay 56L through'lower innermost break contacts of relay 551. This operates relay 505, which connects ground with its lower contacts to conductor 523, operating thereby relay 655 in a circuit from battery throughv its lower winding, lower innermost make contacts of relay 555 to said ground on conductor 523. Relay 05I also operates relay 062 in a circuit from battery through the winding of .relay 662, lower make contacts of relay 50 I lower outermost break contacts of relay 554, when this relay releases as hereinafter described, over conductor 525, through apparatus of Fig. 5, over conductor I55, upper middle break contacts of relay I50, to ground on the lower outermost break contacts of relay I59, when this relay releases after its locking circuit is opened by the operation of relay 9 I2, as hereinafter described. Relay 555 in operating supplements the operating ground for relay with a holding ground connected through the upper innermost contacts of relay 556 and lower innermost break contacts of relay 550. This is necessary to avoid premature disconnection of the coin-control circuit in connection with overtime monitoring as will be discussed later. Relay 556 also connects ground, with its upper middle contacts to conductor 5I5 and thence through upper next-tooutermost break contacts of relay 802, break contacts of jack 853 and winding of the time signal relay 800 to battery. The operation of this latter relay will be discussed hereinafter. Relay 556 also connects ground to conductor 519, through a circuit tracedfrom ground on the lower nextto-innermost operated make contacts of'relay i, lower outermost contacts of relay 656 to conductor 5I9. Relay 556 also closes a holding circuit for relay 559 which is traced from battery through the winding and lower innermost operatedcontacts of relay 559 to ground on the lower neXt-to-innermost make contacts of relay 556.

Relay 555 also partially prepares, with its lower innermost contacts a circuit for operating relay When the link circuit has completed its functions as evidenced by the presence of ground on v sleeve conductor 52I, it operates relay 521 over make contacts of relay 554 to said ground on conductor 52L Relay 52! connects ground to conductor 520, which ground is extended through the lower next-to-outermost make contacts of relay 554, lower innermost make contacts of relay 655 to battery through the winding'of relay 651 which operates. Relay 051 operated (11) connects conductor 526, through upper next to innermost' ground to conductor MS, with its .upper outer energizes the upper winding of relay 556 in a' circuit from battery through the upper winding of relay 655,upper next-to-innermost make con-;

tacts of relay E5! to ground on the lower next-toe;

innermost contacts of relay 655, this same ground also operating link release relay 503, through upper next-to-outermost make contacts of relay 855 over release lead 520; (e) partially prepares the operating circuit for relay H2 byconnecting ground from the upper outermost make contacts.

of relay 559, through lower outermost make contacts of relay 651 to the upper innermost break contacts of relay 654, which connect to the wind ing of relay H2, over conductor 613. Relay'503 in operating releases relay 505, causing the re-- lease of relay 508, and secondary select magnet 56?. As before stated, hold magnets 509, '5I0, M I and 512 are held by ground on conductor 52L When ground is connected to the sleeve conductor I54, a circuit is closed for holding relay I20 of Fig. 1 through its upper winding and for operating relay I'2I through its lower innermost normally closed continuity contacts. Relay IZI looks through its lower innermost make contacts to ground-on the upper middle make contacts of relay I20, and'disconnects with its lower middle break contacts" the start lead I00 from'groun'd on I 7 Relay- 502 accordingly releases dueto the opening of the the lower middle contacts of relay I20.

locking circuit through its lower winding; when relay 503 operates and deenergizes the primary select magnet 504.

The release of relay 505, as before described,- removes ground from conductor 522 thereby causing the release of relay 554. Relay554 disconnects conductors 526', 520 and 524 and transfers conductor 523 from the lower winding of relay 550 to conductor 0H5 so that the alarm circuit will function if conductor 523 is grounded for an abnormal length of time. The release of relay 654 also" closes the circuit for operating re-- I lay H2, which circuit was traced hereinbefore;

For coin-collect calls, relay 659 is operated as described hereinbefore, andholds to ground on the lower, next-to-innermost contacts of relay 656.' Relay H2 operated closes the holding circuit for relay 663, which is traced from ground on the upper outermost make contacts of relay H2, over conductor 638 to the lower innermost contacts of relay 663; also the holding circuit for relay H3 which is traced from ground on the upper middle make contacts of relay H2 to the upper innermost make contacts of relay H4.

Relay "H2 connects ground to interrupter Hl over av circuit from interrupter HI, through lower innermost make contacts of relay H2,

over conductor 65!), through lower outermost break contacts of relay 892, over conductor. 613,

to ground on the upper outermost make contacts of relay 659. At the first ground closure of interrupter H I, relay H4 operates through its upper inner normally closed contacts and winding and resistance H6 to battery and'locks through its upper inner make contacts to ground on the upper middle make contacts of relay 1 l2. Relay H5, is shunted by ground connected to its winding through its upper inner break contacts and does not operateiwith relay H4 at this time. When ground'is removed by interrupter Hi at the end of the first ground closure, relay H5 operates in a circuit from battery through resistance HI, winding of relay H5 to ground on the upper inner make contacts of relay l M. Relay H5 in operating operates relay 663 in a circuit that is traced from battery through the winding of relay 663, over conductor 653,through lower innermost break contacts of relay 805, over conductor 105, through lower neXt-to-outermost break contacts of relay. H8, lower outer break contacts of relay H9,lower inner make'contacts of relay H4 to ground on the lower make contacts of relay H5. Relay H5 also connects ground through its lower make contacts, lower inner make contacts of relay H4, lower outer break contacts of relay H9, upper next to-outer most break contacts of relay H3, lower ,outer break contacts of relay 12!), over conductor 649, through upper innermost break contacts of .relays 658and 660 to conductor 5l8; thence over conductor 5l8, through the contacts of cross-bar switches and 550 to" conductor NH and the winding of .relay H2, which operates. Relay 663 operated (a) locks over conductor 538 to ground on the upper outermost contacts of relay H2; (b) partially prepares a circuit for operating relay H9 over conductor 643 by closing its lower 'middle contacts; (0) connects coin-co1lect battery 664, through resistance lamp 665 and the winding of'relay 566 to conductors 545 and 5&6 over the following circuit path: lower outermost operated contacts of relay 659, lower neXt-tooutermost break contacts of relay 658, upper innermost make contacts of relay 663, over conductor 64!), upper middle break contacts of relay H9, over conductor 631 to the center terminal of the primary winding of transformer 5G1, thence through theleft section of said winding, upper outermost break contacts of relay 554, over conductor 6M and through the upper innermost break contacts of relay H8 to conductor 6m, thence through the upper innermost break contacts of relay 668 to conductor 515: the path to conductor 5l6 is traced through the right section of the winding of transformer 661 overconduc- I calling telephone station H13.

necting, to conductor 516, aforesaid. Conductors M5 and 5% are extended through the apparatus of Fig, 5, over conductors IE2 and 153 through the upper outermost make contacts, and lower innermost make contacts of the operated relay H2 over the line conductors of the Relay E66 operates in the circuit, above traced, provided "that a coin N35 has been deposited in the coin box I04, which has thereby connected ground I09 through coin-box contacts 168, and the winding of coin magnet Its-to the tip conductor of line Hill, and through the switch contacts of the telephone of station I03 to the ring conductor of said line. Coin collector magnet I08 is now operated and collects coin I05 in the manner well known in the telephone art. Relay 666 operated, operates relay (2| over conductor 633. Relay [2! operated connects (a) ground to the winding of relay 655, over a circuit traced from the Winding of. relay 56L through lower innermost break contacts of relay 6%, over conductor 632, to ground on the upper innermost make contacts of relay MI; (1)) looks through its lower innermost make contacts, over conductor 528 to ground on the upper outermost contacts of relay 656; (0) partially prepares a circuit through its lower outermost make contacts for operating relay 568. At the second closure of the contacts of interrupter H i, relay l M is shunted by ground connected through the upper innermost make contacts of relay H5, to the lower terminal of the winding of relay H4. Relay HG releases, but relay H5 is held operated through the upper inner normally closed contacts of relay lid, to ground on interrupter H I. When interrupter H l removes the second application of ground, relay H5 releases. Relay H5 released operates relay H9 in a circuit from battery through the winding of relay H9, over conductor 643, lower middle make contacts of relay 553, lower middle break contacts of relay 668, over conductor to ground. on the lower break contacts of relay H5; its upper middle break contacts the circuit for the coin-collect battery 564, before traced, thus releasing relay 555; (b) locks to ground on its upper innermost make contacts over conductor (0) operates relay 855, if relay 128 has failed to operate due to the absence of ground H39, because of failure to deposit a coin, or for any other reason. Theoperating circuit for relay 805 is traced from battery through the winding of relay 855, over conductor EGG, lower innermost break contacts of relay 1 It, upper middle break contacts of relay lZI, lower nextto-innerrnost break contacts of relay H3, lower innermost make contacts of relay H9, over conductor 648, through upper innermost make contacts of relay 555, over conductorv 505, to ground on the lower middle break contacts of relay 882. If relay I21 has operated, in response to the operation of relay 665, as before described, thus indicating the presence of ground at coin box HM, a test is now made to determine whether the coin box N14 has been satisfactorily cleared, as it normally-should be cleared, by the operation and release of the coinfmagnet I08. Under this condition, at the beginning of the third ground closure of interrupter HI, relay H4 operates, but relay H5 is shunted and does not. operate, as hereinbefore described in connection with the Relay H9 operated, (a) opens with' 1st I first ground closure of interrupter H I. At the 15 Ti-fend of the third ground closure of interrupter l! l, relay lit also operates and now relay 668 is .7 operated in a circuit traced from battery through the winding of relay 5%, over conductor 6H, through upper next-to-innermost break contacts of relay "HS, lower outermost make contacts of relay 'l2l, over conductor 535, through upper middle make contacts of relay 662, operated as hereinbefore described, over conductor 644, lower outermost make contacts of relay H9, lower innermost make contacts of relay M4, to ground on the lower make contacts of relay 7 l5. Relay 658 operated (a) partially prepares the circuit for operating relay etc, as will be hereinaiter described, by closing its lower middle make contacts; (2)) looks to ground on its upper next-to-cuterniost contacts, through upper nextto innermost contacts of relay HS, and lower outermost make contacts of relay 12!; (c) closes a circuit for charging the condensers at station we, and the line capacity through the winding of relay 659, which circuit may be traced from battery through the winding of relay 669, lower innermost make contacts of relay .568, thence over the ring conductor to station Hi3; another path for the tip conductor may be traced by way of the lower innermost break contacts of relay 6% and upper innermost make contacts of relay 663 to said tip conductor. Relay 669, even though the coin has been successfully cleared.

due to the capacity charging may operate momentarily, but its contacts are ineffective to operate relay 722 until relay 1M releases at the beginning of the fourth closure of interrupter ill. Assuming that relay 659 does not operate efiectively due to the successful clearing of the coin, then a circuit is closed for operating release relay 6% which is traced from battery through the winding of relay 65!), upper middle break contacts of relay 655, over conductor 62E,

upper outermost break contacts of relay J22,-

over conductor 523, lower middle make contacts of relay $68, over conductor Bill to ground on the lower break contacts of relay H5, when it releases after the end of the fourth ground closure from interrupter H i. The coin-control circuit is-then released as will be hereinafter described. If, however, relay 659 operates steadily due to a stuck coin, then when relay Hi releases, at the beginning of a fourth ground closure from interrupter TH then a circuit is closed for operating relay F22, which circuit may be traced from battery through the winding of relay 722, over conductor 623, contacts of relay 859, lower outermost contacts of relay 5%, over conductor 6E9, through upper outer break contacts of relay 1.29, lower inner break contacts of relay M4 to ground on the lower make contacts of relay H5. The circuit operation of relays lid and M5 for the beginningof the fourth ground closure is the same as that for the beginning of the second ground closure hereinbefore discussed. Relay 322 operated (a) locks through its lower make contacts, over conductor 821 to ground on the upper outermost contacts of relay 663; (b) closes ground with its upper innermost contacts, over conductor 622, to the winding of relay 569, thereby discharging the capacity of the calling subscriber line to prevent bell tapping when relay see is removed from conductors E25 and'hifi; (c) closes a circuit for operating relay 885, which is traced from battery through the winding of relay 8&5, over conductor TM, through lower innermost break contacts of relay H3, upper outermost make contacts of relay I21, and lower contacts of re 1 connected to relay "22 to the holding ground lay 122.

The before-given description covers the condi tion, on a coin-collect call, which exists when a coin is found in the coin box and iseither cleared or not cleared. The condition, when acoin is not found, will now be discussed; If no coin is found, relay i556 fails to operate and like-,- 3

wise relay l2! When relay ll 9 operates,.a circuit is also closed for operating relay. 895, which is traced from battery through the windingyof relay 8%, over conductor 1M, through lower innermost break contacts of relay i-lky'upper, '7

middle break contacts of relay 22!, lower nextto-innerrnost break contacts of relay H3, lower tacts of relay $59, over conductor iiiiii to ground on the lower middle break'contacts of relay 802.

Relay 855 operated releases relay 865, which =op- 1 era-ted when relay 66! operated. The operating circuit for relay 806 is traced from ubattery.

through the winding of relay SWLIIOWQI outer I most break contacts of relay 86.5 over conductor 693 to ground on the upper outermost contacts of relay 83!. Relaytlfli operated, with itsdower innermost break contacts removes ground from Y conductor EM and opens the operating circuit of relay N2 of the district junctor circuit of Fig. 1. Relay Silt is slow to release to permit relay M2 to release before relay H8 is operated to avoid clicks at the calling station. .ReIay'HB is operated from battery through its winding, over conductor 768, through right outeribrea'k contacts of relay 8%, upper innermost makecontacts of relay 895, over conductor 6.00 to ground on the upper outermost break contacts foi relay 666. Relay H8 operated (a) connects transmission conductors tilt and 5M by means of its outermost make-contacts to conductors 1% and llltextending to ,theline-splitting jack 801 but these conductors are not usedfor jstuck'coin conditions; (1)) connects-conductors'di!) and M2 to conductors 1B! and 1%, respectively, extendi ing to the inner make contacts of relay 862; (a) partially prepares the operating circuit for relay 802 by connecting ground, with its upper nexttoouterrnost make contacts, to conductor 8-H;

'(cl) releases relay 668 byopening its operating circuit with its upper next-to-innermost break contacts; (e) partially prepares a circuit for lighting lamp Wit by connecting battery through its lowernext-to-innermost contacts over'conduotor 789', through upper outermost break con tacts of relay 8%, over conductor 6M thrbugh,

outer lower make contacts of relay H4, over conductor 852, through upper middle break con-,

tacts of relay 6%, upper outermost break contacts of relay 668, through lower innermost make contacts of relay 6-152, over conductor 645,,and

through lamp 895] to ground. Due to the interrupted operation of relay l M, lamp will flash.

This is a signal to the operator thatthe coincontrol circuit has failed ona coin-collect'call which may be due either to no coin in the coin box, or to failure to collect, assuming that the coin is present. Accordingly, the plug of. the cord circuit 837 is inserted into jack 8519, associated with lamp 800, operating relay 832 over the,

sleeve circuit and extinguishing lamp 899. .The

operator will now endeavor'to collect the coin by 1 operating coin, collectkey 8H2, which will connect coin-collect battery 833 to the tip'and ring of the line. If a coinis" present pilot relay M5 ground on conductor 525..

will, operate, lighting the pilot lamp 8I6; if no coin is present relay 8I5 will not operate and lamp 8I6 remains unlighted. If lamp 8I6 lights, the operator will close the circuit a second time, and if it remains lighted it is an indication that the coin is stuck and cannot be collected. Relay 802 operated also (a) connects condenser 8I'I across the tip and ring conductors under control of relay 806; (1)) holds relays H8 operated to ground through its upper next-to-innermost contacts; operates relay H3 over conductor I28 to ground on its lower next-to-innermost make contacts; (d) opens, with its upper next-to-outermost break contacts the circuit of the alarm relay 804 so that an alarm will not be unnecessarily given if the operator keeps the plug of the cord circuit 831 in jack 809 for a long interval. The purpose of relay M3 for the type of call being described is to guard against premature disconnection should the operator inad-H vertently plug into the release jack BIB instead of into the monitoring jack 809. Relay I I3 operated (a) locks through its uppernext-toinnermost make contacts to ground on the upper innermost contacts of relay I I2; (b) releases relay 805 by opening the operating circuit hereinbefore traced and thereby operates relay 806 over conductor 603; (0) partially prepares the circuit for operating release relay 660 in a circuit from battery through the winding of relay 660, upper outermost make contacts of relay 662, overconductor 608, upper innermost make contacts of relay H3, over conductor I30 to ground on the left contacts of relay 834, which operates when the operator inserts a plug into release jack 8I0;

(d) closes a holding circuit for relay H8, which may be traced from battery through the winding of relay ,II8, lower outermost make contacts'of relay H3, over conductor 629, through lower outermost make contacts of relay 662, over conductor 601, through next-to-outermost make contacts of relay H8 to ground. When the operator removes the plug from jack 809, relay 802 releases and relights lamp 800 until the operator inserts the plug into release jack 810, which operates relay, 834. Relay 834 operated, operates release relay 660 over the circuit hereinbefore traced and connectsground to conductor 605, which connects with conductor I9 extending into the link and control-circuit of Fig. 5, there by keeping relay 506 operated and causing the coin-control circuit to be inaccessible to other district junctors requiring service, until the operator removes the plug of cord circuit 831 from jack 3H). 7 from its connectionwith the district junctor circuit of Fig. l whenrelay 660 operates. This feature will be described in detail hereinafter.

The operation of the system for coin collection after thecalling party has disconnected has been discussed hereinbefore. The operation for coin return, after. disconnection, will now be described. Assuming, that connection of the coin-control circuit of Figs. 6, 7 and 8 has been established with the district junctor circuit of Fig. l ashereinbefore described, ground on the lower outermost break contacts of relay I49 will v be connected through upper middle break contacts of relay I50 to conductor I65, thence through switch contacts ofFig. '5 to conductor 525. Coin-return relay 658. is thenv operated from battery through the winding and the lower outermost make contacts'of relay 654 to said Relay 658 operated (a). :connectscoin-retrirn battery .610, through The coin-control circuit is released resistancelamp 6', lower middle make contacts 7 .of relay 658, and thence over the circuit path before described for coin collect to the coin box J04 ofthe calling station; (b) operates from ground on its upper outermost contacts, over conductor 633, relay 'I2I; (c) looks through its lower innermost contacts to ground on the contacts of relay 655, as did relay 659 in the beforegiven description; (12) operates relay "H2 from ground on'its lower outermost contacts, over the path previously traced for operation by relay 559. For an oflicial or free call, the completing trunk, not shown, is arranged so that relay I46 and relay I49 do not operate and consequently the circuits function as for an incompleted call.

The operation of coin-return relay 658, as before described, causes the coin at coin box I04 to be returned, the circuits functioning in a manerator, observing the steadily lighted lamp 800,

now knows that the coin should be returned, and accordingly operates return key- 8I3.. If there is a coin present relay 8M operates and lights pilot lamp 8| 6; if the coin clears then lamp 8I6 is not lighted on the second attempt, but if lamp BIG 1 is relighted, this indicates that the coin is stuck and cannot be returned.

The operation of the system will now be discussed for the condition, whereby after the expiration of a predetermined time interval following the establishment of the conversational con nection between calling and called parties, the deposited coin is automatically collected during conversation anda warning tone is connected to the line to indicate that the expiration of the time limit is approaching. It has been found convenient to collect the coin at the end of approximately four and one-half minutes, that is, one-half minute before the end of a five-minute period covered by the initial coin deposit. It is to be understood, however, that any other time interval that may be desired can be used. At the. end of this five-minute period, if no additional coin has been deposited, an overtime monitoring operator is called in to, supervise the connection.

Let it be assumed now that the called party has answered and that the cams I5I, I52 and I53 have begun. to time the call. As soon as the timing device moves off-normal, normally closed contacts I69 open. At the end of 265 seconds, pick-up contacts I'II close and thereby provide a circuit for holding operated rotary magnet 458, after the charge relay I49 releases, as will be described hereinafter. that is, at the expiration of about four and onehalf minutes, contacts I close, thus operating .relay I20 over a circuit traced from ground through the lower winding of relay I20 and contacts I'II] to battery through resistance I59. Relay I20 operates and then operates relay I50 in a circuit from battery through the winding of relay I50, upper innermost, make contacts of relayv I20, loweroutermost contacts of relay I36,

About five seconds later,

to ground through the upper outer contacts of relay I I1. Relay I20 operated (a) connects battery II8 through resistance H9, upper outermost make contacts of relay I20, upper innermost make contacts of relay I49 to line register I56, through corresponding contacts of the line link cross-bar switches IOI and I02, and register I56 operates to indicate the completion of a call over its associated line; (b) partially prepares with its upper middle make contacts a ground connection to hold relay I2I operated, when this relay subsequently operates; (c) locks through its lower winding, lower innermost make contacts, and upper innermost break contacts of relay I2I to battery through resistance I59; (d) connects ground, with its lower middle make contacts, through lower middle break contacts of relay I2I to start conductor I60 to summon a coin-control circuit; (e) provides an auxiliary holding ground for relay I36 which is traced from ground on the lower outermost make contacts of relay I20, through lower and upper innermost make contacts and winding of relay I36 to battery. This has no useful function at this time.

When the connection to the coin-control circuit is established as hereinbefore described in connection with the operation of the system for coin control after the calling party disconnects, relay I2I operates and the coin-control circuit receives a signal over conductor I57 to collect the coin. When this signal is received the coincontrol circuit functions, as before described, except that now relay 662 is not operated, since there is no ground on conductor 525 because the calling party has not disconnected. With relay 662 not operated, a warning tone will be superimposed on the line conductors 5I5 and 5I6 through the windings of transformer 66?. This tone is produced by battery interruptions furnished by the interrupter 6'14 and transmitted through transformer 612, lower middle break contacts of relay 662, lower middle make contactsto the coin-control circuit path before traced.

When relay H6 operates, as hereinbefore described, it operates release relay 660, provided a coinhas been found in the coin box- I04, in a circuit from battery through the winding of relay 660, through upper outermost break contacts of relay 662, over conductor 64! through lower middle make contactsof relay 'I2I, lower innermost make contacts of relay H6, over conductor 648, upper innermost contacts of relay 659, over conductor 606 to ground on the lower middle break contacts of relay 802. Relay 660 operating, releases the coin-control circuit, as hereinafter to be described. The stuck coin test, using relay 669, which test was hereinbefore described, is not made at this time, so as to avoid interrupting conversation. This test is made after disconnection. However, if the coin-control circuitfinds that no coin has been deposited as evidenced by the non-operation of relay 666 and consequently of relay 12! then a circuit is closed for immediately flashing the overtimemonitoring lamp 80L This circuit is traced from ground through lamp 80I, over conductor 64?, lower innermost break contacts of relay 662, thence over the circuit before traced for coin-control lamp 600'. When the operator observes the flashing lamp 80!, the plug of the cord circuit 8 is insert-ed in the overtime monitoring jack 806, relay 002 operates and the circuit functions as before described. Relay H2 of the district junctor circuit is operated as before described in connection with a stuck coin condition and the callingline is circuit for, relay connected to conductors I62 and I63, The called subscriber is bridged across the connection by means of conductors I66 and I67.

the cord circuit collect key 8I2.

The operation of the system for overtime monitoring by an operator will now be described.

For this con- I dition, the operator requests the deposit of a coin which she immediately collects by operation off5 When the test indicates at the end of the five- I minute period that a coin has been deposited, the

coin-control circuit is released and conversation through the district junctor is-uninterrupted. If no coin is found then the monitoring operator is signaled with a steadily lighted lamp, and the operator upon answering the signal requests that I the calling subscriber deposit a coin in payment for the succeeding overtime interval or permits the calling party to disconnect if the conversation is to be terminated.

connects, the operator removes the cord circuit plug from the monitoring jack and the coin- If the calling party maintains that a coin has been deposited or disnects a second time, the coin-control circuit repeats the procedure of verifying disconnection or the presence of a coin at the calling station. When a coin is found present, the coin-control circuit dismisses the district junctor. If disconnection is detected, the coin control circuit is required to proceed with coin-return service to insure that the coin-box station has been properly cleared.

' The operation of the system for overtime monitoring will now be discussed in detail. Let it be assumed that the district junctor circuit shown on Fig. 1 has'cooperated with the coin-control circuit of Figs. 6, 7, 8 to collect, at theend of the four and one-half minute period, the coin contacts of relay Ill. Relay I50 also remains net I58. A small interval before the timing device completes a cycle of five minutes contacts- I69 reclose', and. a circuit is closed for operating relay I20, which relay released when ground wasv removed from conductor I64 following the dismissal of the coin-control circuit after the four and one-half minute period. The I20 is. traced from ground through its lower winding, lower outermost make contacts of relay I50, contacts I69, upper outermost make contacts of. relay I50,land -resistance I56 to battery. The operation of relay I20 sumtery through thewinding of relay I50, upper innermost make tcontactsof relay 1.20,. lower ."outermost contacts of relayrI36 to ground on tor I8 causes relay II2 of the district 'unctor the upper outermost contacts of relay 1. v Mag- -net I58 is held to the same ground through the lower innermost contacts of. relay I50, and the timing device continues to function. However, the actual timing of the callwill not be resumed until the coin-control circuit is released; When I this occurs the holding ground on conductor I64 is removed,and relay I20 releases, thereby releasing relay I60. The release of relay I50 opens the operating circuit of magnet I58, which is so constructed that it now immediately restores .to normal and the timing of the call isresum'ed. .If, however, assuming an extreme condition,xthat the coin control circuit should beheld until contacts. III reclose, thereby maintaining the operation of magnet I58, the district junctor must then wait until contacts IH open, that is, until the timing mechanism has restored to normal, before timing is resumed. As herein before stated, the presenceof. ground on con-' 604, through upper innermost break contacts of relay H8, over conductor filll through upper innermost breakcontacts of relay 668 to aforementioned conductor 5I5. Relay 655 looks, when relay 656 operates, in a circuit through its lower middle make contacts,.upper innermost break contacts ofrelay 662 to ground on the lower next-to-outermost make contactslof relay 656.;

After the link and control circuit of Fig. 5 has operated relay 65Iit releases and causes the release of relay 654 as before described. When .relay 654 releases relay H2 operates from ground on the upper neXt-to-outermost contacts of relay 665, over conductor 650, through lower outermost .break contacts of relay 802,.over conductor 6I3 through lower outermost make contacts of relay 651, upper innermost break contacts of relay 654, over conductor Y613 and through winding of relay II2 to battery. Relay H2 operated connects ground on the upper next-to-outermost contacts of relay 655, over conductor 650, through lower innermost contacts of relay H2 to interrupter II I; (b) connects locking groundw'ith. is

upper outermost contacts, over conductor 638, -to the lower innermost make contacts of relay 663, and with its upper middle contacts to the upper inner make contacts of relay I I4; (0) connects ground to ring conductor 5I4 to guard against clicks to the subscribers when the trans-, mission circuit of the district junctor circuit is interrupted 'to permit testing the calling coinstation for the presence of they overtimedeposit. This circuit is traced from conductor 5I4, through lower outermost break contacts ofrelay H8, through lower middle make contacts of relay II2,"over conductor H0, through upper innermost break contacts of relay 805, over cone =ductor 600 to ground on the upper outermost break contacts of relay 660. Relays I I4 and H5 now operate and release in response to ground interruptions furnished by interrupter HI. When relay H4 operates, it operates relay 663.

and connects ground to conductor .5I8, over cirground closure from interrupter II I.

cults vh'ereinbefore traced. Ground on conducto operate, which connects the calling station to conductors I62 and I63 extending to the coincontrol circuit. Relay 663 operated operates relay 660 in a circuit from battery through the winding of relay 668, over conductor .6I I, through upper next-to-inn'ermost break contacts of relay H8, through lower outermost break contacts .of relay I2I, over conductor 636, through upper next-to-outermost make contacts of relay 663 to the same ground that. is holding relay 655. Relay663 operated also partially prepares a circonductor 643, through upper and lower next-. to-innermost contacts of relay 663,: over conductor 624,,to the open upper middle make contacts of relay 805, thence over conductor 63I, through relay 660 by closing its lower middle make contacts; (b) closes the circuit for charging the station condensers and the capacity of the calling line through the winding of relay 669 which has its contacts made ineffective for a short [interval in order to guard against false operation of relay I22 on line surges; (c) prepares a circuit, for operating relay I22 if a coin is present in coin box I06, all of which has been described in detail in connection with operation for stuck coin conditions. If relay 669 should operate on any line surges at this time, it should release before its contacts are made effective when relay H4 releases at the beginning of the second ground closure from interrupter iii. If a coin has been deposited, relay 669 will operate as soon as relay 66B operates, so that when relay II4 releases, relay I22 will operate. immediately. Relay I22 operated (a) connects ground to ring conductor 5I6, the circuit being traced ,from ground on the upper innermost contacts of; relay I22, over conductor 622 and through lower innermost make contacts of relay 668 to conductor 5I6; this prevents bell tapping on party coin lines when relay 669 is disconnected fromthe calling line; (b) operates release relay 660 over conductor 630, throughupper outermost .8 aswill be hereinafter described. If a coin has not been deposited relay 660, and consequently relay I22, will not be operated when the contacts of relay 669 are made effective when relay II I releases at the beginning of the second When rolay H5 releases at the end of the second ground closure from interrupter III, a, circuit is closed for operating relay 805 which is traced from groundv on the lower break contacts of relay H5,-

over conductor I04and through winding of re- .lay605 to battery. Relay ,805 looks toground in ,cuit for operating relay H0. This is traced from batterythrough the winding of relay H9, over

Images