US2195627A - Signaling system - Google Patents

Description

April 2, 1940. c. E.'LOMAX El AL SIGNALING SYSTEM Filed May 4, 1939 4 Sheets-Sheet 1 m RS $5 we? ol b QM m E v H. E E .TLIQWVI b3 1 E 85 NS ENE 9Q .eafiw MQQ 9 i I NEW 3Q Si s mg J r 2 37L EFL 7g EG N3 fiS fi e35 r Q96 $1 Q13 w 3Q TSB 96 W9 INVENTOR. CLARENCE E LOMAX BY CHARLES F.FFOLLIOTT ATTORNEYS.

p 1940 c. E. LOMAX ET AL SIGNALING SYSTEM Filed May 4, 1939 4 Sheets-Sheet 4' CHARLES F. FFOLLIOTT ,nfiw m M ATTORNEYS.

Patented Apr. 2, 1940 PATENT oFFic-E- SIGNALING SYSTEM Clarence E. Lomax, Oak Park, and Charles F. v Ffolliott, Wheaton,'lll., assignors to Associated Electric Laboratories, Inc., Chicago, 11]., a corporation of Delaware ApplieationMay 4, 1939,Serial No. 271,696

12 Claims. (01.179-5) The present invention relates to signaling system and, more particularly, to improvements in combination alarm and telephone systems of the general character disclosed in Ffolliott Patent No. 2,122,460,,granted July 5, 1938. s I

In a signaling system of this type, a number of combination alarm and telephone stations are associated with an operator position by a number of lines respectively extending therebetween. Telephoneapparatus is provided at each of the stations and answering apparatus is provided at the-operator position inorder to facilitate the establishment of connections between the stations and the operator position. Furthermore, appa ratus is provided at each of the stations which is selectively operative "to initiate a telephone call or an alarm on the line extending to thestation, whereupon corresponding signals identifyingthe line and the telephone call or alarm initiated thereon are transmitted to the operator position. Also, alarm recording equipment is usually provided at the operator position which is operative automatically to record. the code of a line having an alarm thereon, thereby "to identify the line.

It is an object of the present invention to-provide, ina signaling system of the general character just described,- improved and exceedingly simple apparatus for establishing connectionsbetween the combination alarm and telephonestations and the operator position.

Another, objectof the invention is to provide, in a signaling system of the type described, an improved and exceedingly simple arrangement for-initiating telephone calls and alarms on the combination alarm and telephone lines 'and'for controlling the transmission of corresponding signals to the operator position. r s A further object of theinvention is m provide, in a signaling system of the type described an improved and exceedingly simple arrangement for recording the .code of a line having an alarm thereon, thereby to identify the line.

A further object of the invention is to provide, in a signalinglsystem of the type described, an improved correcting circuit adapted to be utilized in conjunction with a line having a ground fault thereon, in order torender the line usable not withstanding the ground fault thereon, and which embodies, an arrangement for controlling the transmission' of corresponding signals to the operator position when telephone calls and alarms are initiated on the associated line. The'features of the present invention are illustrated as being incorporated in a signaling system including a number of combination alarm and telephone stations, an operator position and a number of lines respectively extendingbetween -the stations and the operator position. Telephone apparatus is provided at each of the stations; and answering apparatus is provided'at the associated with each of the lines; and the line conductors of each of the lines are connected to a source of current.

Inpacco'rdance with one feature of the invention, an enclosing casing having a door is provided at each of the stations; and the telephone,

apparatusat the station is housed in the enclosing casing. The telephone apparatus comprises a repeater provided with first and second windings; a first telephone instrument of the sound powered type and operatively associated with the reduce the effective resistance of the resistor,

thereby effectively to energize the second winding of the repeater in-order to initiate a telephone call V on the line. 'the station which is operative to interrupt the Also, a second switch is provided at line, thereby to initiate an alarm on the line. Finally a hookswitch is provided at the station which is operative to short-circuit the second winding of the repeaterand operatively to associate the second telephone instrument with the a line.

In accordance with another feature of the invention, each of the line circuits comprises a control arrangement includingfirst and second,

relays, the first and second relays and the resistor at the associated station being connected in series circuit relationship with the corresponding line. The first and second relays are so connected and arrangedthat the first 'relayiis normally operated and the second relay is normally restored, the second relay being operated when the effective resistance of the resistor at the associated station is reduced, and the first relay being restored when the line is interrupted, A signaling arrangement is associated with the line circult which is responsive to the restoration of. the first relay or'the operation of the'second relay for transmitting a first signal to the operator position, andresponsiveto the restoration of the first relay following the operation of the second relay for transmitting a second signal to the operator position, Also, it is noted that the controlarrangement provided in the line circuit is responsive. to the presence of an alarm on the corresponding line when the line circuit is associated therewith for controlling thealarm recording equipment, thereby to cause the line to be identified. v

operator position. A line circuit is individually In accordance with a further feature of the invention, a correcting circuit is provided which is adapted to be associated with any one of the lines having a ground fault thereon, thereby to render the faulty line usable notwithstanding,

the ground fault thereon. Also, means is provided which is controlled from the operator position for disassociating the corresponding line circuit from the faulty line and for associating the correcting circuit therewith. Furthermore, a control arrangement is provided in the correcting circuit which is responsive to the presence of a telephone call on the faulty line when the correcting circuit is associated therewith for transmitting a first signal to the operator position, and responsive to the presence of an alarm on the faulty line when the correcting circuit is associated therewith for transmitting a second signal to the operator position. Also, it is noted that the control arrangement provided in the correcting circuit is responsive to the presence of an alarm on the faulty line when the correcting circuit is associated therewith for controlling the alarm recording equipment, thereby to cause the line to be identified.

Further features of the invention pertain to the particular arrangement of the circuit elements thereof, whereby the above-outlined and additional features are attained.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objectsand advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which Figures 1 to 4, inclusive, taken together, illustrate diagrammatically the details of a signaling system embodying the present invention.

Referring now more particularly to Figs. 1 to 4, inclusive, of the drawings, the signaling system there illustrated comprises a central oflice provided with an operator position 00 of the manual type, a number of combination alarm" and telephone stations including the station '50, and a number of telephone substations, including the substation C. Each of the combination alarm and telephone stations is connected to the central office by a combination alarm and telephone line extending therebetween and terminates .in a corresponding jack at the operator position 60, the combination alarm and telephone station 50 being connected to the central oiiice by the line I00 extending therebetween and terminating in the jack J I20 at the operator position 60. Similarly, each of the telephone substations is "connected to the central oflice by a telephone line extending therebetween and terminating in a central ofiice by the line 450 extending .therebctween and terminating in the jack M at the operator position 60. More specifically, the central office may have an ultimate capacity of several thousand combination alarm and telephone lines and several hundred telephone lines, the combination alarm and telephone lines being arranged in groups of 200 lines each. A line circuit is individually associated with each of the combination alarm and telephone lines, the line circuit I80 shown in Fig. 1 being individually associated with the line I00; and a line circuit of any desired type is individually associated with each of the telephone lines, the line circuit MB'bei'ng ing cords, including the patching cord 23! shown in Fig. 2A, a test circuit 200 shown in Fig. 2B, and position apparatus 400 shown in Fig. 4.

Furthermore, the central ofiice comprises alarm recording equipment 300, shown in Fig. 3, which includes a number of finder switches 30.], 302, 303, etc, a finder sequence switch 304, a sender switch 305, a sender sequence switch 306 and -"a recorder -30'I.

The alarm recording equipment 300 is of the type'of that disclosed in Clarence E. Lomaxand John H. Voss PatentNo'. 2,121,159, granted June 21, 1938, and is connected andarranged ina similar manner. More particularly, each of the finder switches 30!, 302, -etc.,"is of the'200' point type and corresponds to an associated group of 200 "lines; the finder sequence switch 304 is operative to select one of the finder switches corresponding to a group of 200 lines including a particular line having an. alarm thereon; the sender switch 305 is operative to transmit an impulse code to the recorder 30-! identifyingthe particular line; the recorder 301*is operative to print a record of the code transmitted thereto; and the sender sequence switch 306 is operative to control the number of repetitions of the code transmitted and thereafter to release the alarm recording equipment 300.

Preferably, "the apparatus provided at each combination alarm and telephone station is identical to that provided atthe station which comprises a telephone instrument A of the common battery type, a telephone instrument B of the magnetic or sound powered type, a ringer,

not shown, a repeater I05, a hookswitch SHO, an alarm fswitch Sll5; and a door switch S113. It is noted that this apparatus at the combination alarm and telephone station 50 is hous'ed in a suitable enclosing easing indicated at 5| which is provided'with a pivotally mounted door 52 operatively associated with the door switch S1 IS in a manner more fully described subsequently. Further, it is noted that the telephone instrument A comprises a transmitter and a receiver, the receiver cooperating with the hookswitch 8H0; while the telephoneinstrument 13 comprises a single transmitter and receiver unit. Furthermore, each of the telephone substations is provided with apparatus including a telephone instrument of the common battery type and a ringer.

Preferably, each of the line circuits individually associated with the combination alarm and telephone lines is identical to the line circuit 180 individually associated "with the line I 00 "which comprises a line relay R140, *an'impulse relay R145, an answer relay Rl30, and a number of control relays RI-50, RIBO, R185 and Rl90. Furthermore, it is noted that the line circuit I80 controls a supervisory 'lamp L114 associated with the jack -J 120 at the operator position 60.

Preferably, each of the patching cords is identical to the patching cord -23| and each of the correcting circuits is identical to the correcting c'ircuit 245. The patching cord 23l comprises two plugs P235 and P240 connected together by three conductors C232, C233 and C234; while the correctingci-rcuit 245 comprises two jacks U246 and J 251, and a number of control relays R260, R205, R210, R2715, R280 and R290. Also, a supervisory lamp L2-5G'arrangedat the operator position 80 is individually associated with-the correcting circuit 245.

The test circuit 200 comprises an ammeter 206, a plug P20I and a number of keys K201, K2 I0 and K2I5, and it is utilized to test the combinationalarm and telephone lines for open circuit, short circuit and ground circuit faults there'- on in a manner more fully'desoribed subsequently.

The operator position apparatus 400 arranged at the operator position 00 comprises a receiver 453, a transmitter 454, a receiver amplifier 415, a transmitter amplifier 410, a number of repeaters M0, 400 and 485, and a cord circuit including two plugs P405 and P440, two ringing keys K405 and K430, and two battery supply relays R426 and R421. Further, the operator position apparatus 400 comprises two keys K4 I5 and K420, a super-' visory lamp L4I9,an audible alarm 444, and a number of control relays R435, R455, R458, R460, R465, R410 and R480.

A better understanding of the connection and arrangement of the apparatus incorporated in the signaling system'will be facilitated from a consideration of the operation thereof incident to the initiation of telephone calls and alarms at the combination alarm and telephone stations. 4

The line circuit individually associated with each of the combination alarm and telephone lines is normally partially operated; For example, in the line circuit I individually associated with the combination alarm and telephone line I00 the impulse relay RI45 is normally operated While the line relay RI40 is normally energized but in a restored position, due to the fact that the last-mentioned relay is of the marginal type. The circuit for energizing the windings of the line and impulse relays RI40 and RI45, respectively, extends from ground by way of the upper winding of RI45, CI'I5, the contacts IBI, the line conductor CIOI of the line I00, the contact II2 of the vhoo-kswitch SI I0, the winding I01 of the repeater I05, the resistor I08, the contacts H6 of the alarm switch SI l5, the line conductor CI02 of the line I00, the contacts I32, the winding of RI 40 and the lower winding of RI45 to battery. As previously noted, the impulse relay RI45 is normally operated, thereby to retain interrupted at the contacts I46 a circuit, traced hereinafter, for energizing the winding of the control relay Rltli; and theline relay ,RI40 is not operated due to the high series resistance of the above-traced circuit, the resistance of this circuit residing principally in the resistor I08.

In order to initiate a telephone call at one of the combination alarm and telephone stations,it is only necessary to open the door of the enclosing casing thereat. For example, in order to initiate a telephone call at the combination alarm and telephone station 50,, the door 52 of the enclosing casing 55 thereat is opened, thereby to cause the door switch SI I3 tobe operated. More particularly, the contacts II4 of the door switch S1 I3 are operated into engagement, thereby, to complete an obvious path for short-circuiting the resistor I00. When the resistor I08 is thus shortcircuited, the resistance of the previously traced series circuit for energizing the winding of the line relay Rl40 is substantially reduced, thereby to cause the current traversing this circuit to be of the slow-to-operate type. Upon; operating, the

line relay RI40 completes, at the contacts 'I4I,

' an obvious circuit for energizing the winding of the control relay Rl50, thereby to cause the latter relay to operate. Upon operating, the relay Rl50oompletes, at the contacts I5I, a holding circuit for energizing the winding thereof, this" circuit extending from ground by way of the contacts I34, the contacts NH, and the winding of RI50 to battery. Also, upon operating, the relay R450 prepares at the contacts I52 a further point in thepreviously "mentioned circuit for energizing the winding of the control relay RI60, interrupts at the'contacts I53 a point in a circuit, traced hereinafter, for illuminating the lamp LI'M associated with the jack J I20 at the operator position 60, and completes at the contacts I54 an alternative circuit for illuminating the supervisory lamp M24. The last-mentioned circuit extends from ground by way of the contacts I54,

the contacts It? and the lamp LI'I4 to battery.

The steady illumination of the supervisory lamp LI I4 associated with the jack J I 20 at the operator position 00 indicates to the operator thereatthat a telephone call has been initiated on'thecombination alarm and telephone line I00 extending to the combination alarm and telephone station 50 andjterminated by the jack J I20. The call on the line Iilllis answered by the operator at the'operator position 50 uponinserting the plug P40I of the cord circuit included in the operator positionapparatus 400 into the'jack J I20 and upon-operating the key K420 to its ofi-normal position. When the plugP40I is inserted into the per "terminal of the winding'l0'lor' the repeater I05 by way of the contacts I I2 of the hookswitch SIIO, CIlli', the'jacktip I2I, the plug'tip 402,

the contacts 406 of the ringing key K405, the

contacts 42I of the key K420, the winding 4I2 of the repeater 4 I 0, the condenser 4N, the wind-,

ing .4I4 of the repeater M0, the contacts 422 of the key K420, the contacts 400 of the ringing key K405, the plug ring 403, the jack ring I22, CI02, the contacts N5 of the alarm switch SI I5 thelower terminal of the winding I01. At this time the windings I06 and lii'I of the repeater I05 are operatively coupled and the Windings4l2, 4I4and4II ofthe repeater 450 are operatively coupled, the winding E00 of the repeater I05 beand the contacts I I4'of the door switch SI I3 to ing included in an obvious operating circuit for the telephone instrument'B, and the winding 4| I of the repeater M0 being included in an input circuit for the receiver amplifier 475. The input circuit for the receiver amplifier 4'35 extends from one terminal of theamplifier 415 by way of the contacts 4'II, the contacts 40!, the winding 4H of the repeater 450, the contacts 404 and the contacts 413 to the other terminal of the amplifier 415. The receiver 453 at the operator position 60 is included in the output circuit of the receiver amplifier 4'55, this circuit extending from one terminal of the amplifier 4'55 by way of the contacts 40L the jack J4'I5, the plug P410, the receiver 453, the plug P4l6, the jack J4'l5 and the contacts 483 to the other terminal of the amplifier 415.

Also, when the key K420 is operated away from its normal position, the input circuit of the transvmitter amplifier 4'56 is completed, this circuit extending from ground by way of the contacts 423 of the key K420 and the contacts 487 to one ter- 1 minal of the amplifier 416 and from the other terminal of the amplifier 416 by wayof the contacts 485, the jack J411, the plug P418, the transmitter 454, the plug P418, the jack J411, and the winding of R458 to battery. The output circuit of the transmitter amplifier 416 includes the windings 492 and 494 of the repeater 496 and extends from one terminal of the amplifier 416 by way of the windings 492 and 494 to the other terminal of the amplifier 416. At this time, the telephone instrument B at the combination alarm and telephone station 56 is operatively associated with the receiver 453 at the operator position 66 and signal currents induced in the telephone instrurnent B when the party thereat speaks into the telephone instrument B will be transmitted to the receiver amplifier 415 and there amplified and conducted to the receiver 453.

When the operator at the operator position i 66 speaks into the transmitter 454, undulating signal currents traverse an alternative path included in the input circuit of the transmitter amplifier 416, this path extending from one terminal of the amplifier 416 by way of the contacts 481, the condenser 415, the jack J411, the

plug P418, the transmitter 454, the plug P418, the jack J411, and the contacts 485 to the other terminal of the amplifier 416. The undulating signal currents traversing the input circuit of the transmitter amplifier 416 are amplified and transmitted over the output circuit thereof, thereby to cause undulating voltages to be induced in the winding 493 of the repeater 496 operatively coupled with the winding 494 thereof included in the output circuit of the transmitter amplifier 416. The undulating voltages generated in the winding 493 of the repeater 496 cause undulating currents to fiow in the circuit of the full-wave rectifier network 461 in an obvious manner, thereby to cause a full-wave rectifier current to traverse the winding of the control relay R465 in an obvious manner. When thus energized, the relay R465 operates to complete at the contacts 466 an obvious circuit for energizing the control relay R466, thereby to cause the latter relay to operate. Upon operating, the relay R466 interrupts at the contacts 46! and at the contacts 464 points in the previously traced circuit for connecting the winding 4 of the re peater M6 in the input circuit of the receiver amplifier 415 and completes at the contacts 462 and at the contacts 463 a circuit for connecting the winding 4 of the repeater M6 to the winding 49I of the repeater 496. The last-mentioned circuit extends from the upper terminal ofthe winding 4 II byway of the contacts 462, the winding 49I and the contacts 463 to the lower terminal of the winding 4! I. At this time the windings 49I and 492 of the repeater 496 are operatively coupled, thereby to cause the amplified undulating currents to be induced in the winding 49I of the repeater 496.

Each time the operator at the operator position 66 speaks into the transmitter 454, the control relay R466 operates in the above-described manner, thereby operatively to connect the winding M I of the repeater M6 to the winding 49I of the repeater 496 in order to cause signal currents to be transmitted from the transmitter 454 to the telephone instrument B in an obvious manner. Each time the operator at the operator position 66 listens, the control relay R466 recurrentsto be transmitted from the telephone 1114 strument B to the receiver 453 in an obvious manner.

, It is contemplated that the party at the combination alarm and telephone station 56 will utilize the sound powered telephone instrument B thereat in conversing with the operator at the operator position 66. However, the party at the station 56 may utilize the common battery telephone instrument A at the station 56. In any case, the common battery telephone instrument A is utilized by the party at the station 56 when the call is to be extended by the operator at the operator position 66 over a telephone line in a manner more fully described hereinafter. Assuming that the party at the combination alarm and telephone station 56 removes the receiver of the telephone instrument A from its switchhook, the hookswitch SI I6 is operated, thereby to interrupt at the contacts -I I2 thereof a point in the previously traced path for connecting the winding I61 of the repeater I65 to the line-conductors C I DI and C I 62 of the line I66 and to complete at the contacts III thereof a path for connecting the telephone instrument A across the line conductors C'I6l and CI62 of the line I66. The last-mentioned path extends from the line conductor CI6I by way of CI63, the telephone instrument A, CI64, the contacts I I I of the hookswitch SI I6, and the contacts H6 of the alarm switch SI I to the line conductor CI62. At this time, talking battery is supplied tothe telephone instrument A from the impulse relay RI included-in the line circuit I86, ground potential being connected to the line conductor CI6I and battery potential being connected to the line conductor CI62 by way of the windings of the impulse relay RI45 and the line relay RI46 as previously explained. Although a very feeble current traverses the telephone instrument A by wayof the windings of the impulse relay RI45 and the line relay RI46, sufiicient current traverses the telephone instrument A to control the receiver amplifier 415. Thus, the telephone ine strument A at the. combination alarm and telephone station 56 may be utilized to converse with the operator at the operator position 66.

A call which is to be extended from one of the combination alarm and telephone stations, such, for example, as the station 56, to one of the telephone substations, such, for example, as the substation C, is first initiated at the combination alarm and telephone station 56- and answered at the operator position 66 in the previously described manner, the telephone instrument B being utilized at the station 56 to converse with the operator at the operator position 66. The operator at the operator position 66 then advises the party at the combination alarm and telephone station 56 to remove the receiver of the telephone instrument A thereat from its switchhook, thereby to cause the telephone instrument A to be connected-across the line conductors CHM and CI62 of the combination alarm and telephone line I66 in the previously described manner. The operator at the operator position 66 then actuates the key K4 I5 thereby to complete at the contacts 4I6 thereof a circuit for energizing the lower winding of the control relay R435, this circuit extending from ground by way of the lower winding of R435, the contacts 424 of the key K426 and the contacts MB of the key K4I5 to battery. When energized over the above-traced circuit, the relay R435 operates to complete, at the contacts 438, a holding circuit for energizing'the upper winding thereof in series with the winding of the answer relay RI30 in the line circuit- I80 individually associated with the line I00. This circuit extends from ground by way of the upper winding of R435, the contacts 438, the plug sleeve 404, the jack sleeve I23, CH6 and the winding of RI30 to battery. When energized ,over the above-traced circuit, the answer relay RI30 operates to interrupt, at the contacts I34, a point in the previously traced holding circuit for energizing the winding of the control the winding of R480 to battery. When energized over the above traced circuit, the relay R400 relay BI50 and completes, atthe contacts I35, an obvious holding circuit for energizing the lower .winding of the impulse relay RI45. Also, the answer relay'Rltil interrupts, atthe contacts I3i and at the contacts I32, the previously traced series circuit for energizing the windings of the line relay R440 and the impulse relay RI45, thereby to clear the combination alarm and telephone line Hill of impedance elements. Further, the answer relay BIZ-i0 completes, at the contacts I33, a circuit for energizing the winding of the line relay RI40 in a reverse direction, ground by way of the contacts 535, the winding of RI40, the contacts I33 and the resistor I I8 to battery. When the above-traced circuit is completed, the line relay R140 quickly restores and does not reoperate due to the high resistance of the resistor IIB. Upon restoring, theline relay RI40 interrupts, at thecontacts MI, the previously traced original circuit for energizing the vwinding of the control relayRiiW, thereby'to remainder of the relays in the line circuit I00 occupy their restored positions at this-time.

Also, upon operating, the control relay R435 completes, at the contacts 439, a series circuit for energizing the winding of the relay R455 and for illuminating the supervisory lamp L4I9, this circuit extending from ground by way of the contacts 439, the contacts 428, the lamp L4 I0, and the winding of R455 vto battery. When energized over. the above-traced circuit, the control relay R455 operates to prepare, at the contacts 456, a circuit, traced hereinafter, for operating the alarm 444, The illumination of the supervisory lamp L4H) gives the operator at the operator position 00 answer and disconnect supervision in connection with the called telephone line in a manner more fully described hereinafter. Furthermore, the control relay R435 completes at the contacts 435 a series circuit for energizing the windings of. the control relays R410 and R400, this circuit extending from ground by way of the contacts'439, the contacts 425 of the key K420, the'winding of R470 and the relay R480 interrupts at tl'ie conta'cts 48I and 1 at the contacts 483the connection between the receiver 453 and the output circuit of the ref this circuit extending from ceiver amplifier 415, completes at the contacts 482. and at the contacts 484 an operative connection between the receiver 453 and the winding 490 of the repeater 435, interrupts at the contacts 485and at the contacts 48'! the connection between the transmitter 454and the input circuit of the transmitter amplifier 416, and completes at the contacts 4% and at the contacts 488 an operative connection between the transmitter 454. and the windings 458 and 499 of the repeater 495. The circuit for operatively connecting the receiver 453 to the winding 496 of the repeater 495 extends from one terminal of the receiver 453 by way of the plug P415, the jack J4'i5, the contacts 482, the winding 4%, the condenser 438, the contacts 404, the jack J4I5 and the plug P434 to the other terminal of the receivertriii. The circuit for operatively connecting the transmitter 454 to the windings 438 and-499 of the repeater 495 extends from ground by way of the contacts 423 of the key K420, the contacts 488, the windings 499 and 498, thecon- ,tacts406, the jack J4I'I, theplug P4'I't, the transthe connection between the winding 4 of the repeater 4m and the input circuit of the receiver amplifier 445 and completes at the contacts'4l2 and at the contacts 474 a connection between the winding 4M of the repeater M0 and thewindings 4% and 49? of the repeater 495.

The last-mentioned connection extends from the upper terminal of the winding of R4 by wayroi the contactsdtt, the contacts 412, the

windings400 and 491, the contacts 414, and the contacts 404 to the lower terminal of the winding Al I. v

Finally, upon operating, the control relay R435 completes, at the contacts 430 and 43?, a loop circuit extending between the battery supply relay R423 and the, telephone instrument A at the combination, alarm and telephone station 50.

This loop circuit extends from ground by wayof the upper winding-of R426, the contacts 436 and the contacts 406 of the ringing key K405 to the plug-tip 402and from battery by way of the lower winding of'R lZE, the contacts 431 and the contacts 408 of the ringing key K405 to the plug ring 403, theplug tip 402 and the plug ring 403 being included in a circuit extending to the telephone instrument A at the station 5i as previously explained. Thus, atthis time, the common battery telephone instrument A at the combination alarm and telephone station 559 is operatively associated with the receiver 453 and the transmitter 454 at the operator position 60 by into the jack J445 individually associated with the telephone line 450 and then operates the ringing key'K430 away from its normal position,

, thereby to cause ringing current to be projected over the telephone line 450 to the telephone substation C. The circuit for projecting ringing current to the telephone substation C extends from one terminal of a source of alternating curterminal of the source of alternating current supply by way of the contacts 434 of the ringing key K430, the plug ring 442, the jack ring 441. and the line circuit 449 to, the line conductor C452 of the telephone line 450, the ringer atv the telephone substation C being bridged across the line conductors C454 and C452. The operator at the operator position 60 operates the. ringing key hack and forth between its normal and.- 01T- normal positions intermittently. When the party at the telephone substation 0 answers. thecall, a loop circuit is completed between the telephone instrument thereat and the battery supply relay R421. when the ringing key K430 is restored to its normal position, this loop circuit extending from ground by way of the upper winding of R421 and the contacts 43.! of the ringing key K430 to the plug tip 44! and from battery byway of the lower winding of R421 and the contacts 4.33 of the ringing key K430. to. the plug ring 442, the plug tip 44! and the plug ring 442 being included in the loop circuit extending to the telephone sub-F station C as previously explained. When the loop circuit is completed between the telephone instrument at the telephone substation C and the battery supply relay R421, the windings of the last-mentioned relay are energized, thereby to.

loop circuit extending between the telephone instrument A at the combination alarm and telephone station 50 and the battery supply relay R429 and the loop circuit extending between the telephone instrument at the telephone substation C and the battery supply relay R421 are operatively connected, the upper windings of the relays R425 and R421 being connected together by way of the condenser 4H and the lower windings of the relays R426 and R421 being connected to-.

g-ether by way of the condenser H8.

The operator at the operator position 60 may monitor the established connection, between thecombination alarm and telephone station 50 and the telephone substation C or she may-disconnect from this established connection. Inorder to disconnect from the established connection, the

operator at the operator position 60 restores the keys K415 and K420 to their normal positions.

When the key K420 is restored to its normal position, the previously traced series circuit for energizing the windings of the control relays R410 and R480 is interrupted at the contacts 425 thereof and the previously traced circuit for energizing the winding of the control relay R458 is interrupted at the contacts 423 thereof, thereby to cause the last-mentioned relays to restore.

Upon restoring, the control relays R410 and R480 interrupt the previously traced connections between the receiver 453 and the transmitter 454 and the repeater M0 by way of the repeater 495 and complete the previously traced connections between the receiver 453 and the transmitter 454 and the repeater M0 by way of the amplifiers 415 and 416. Upon restoring, the control relay R458 prepares at the contacts 459 a point in the preares-e27 viously mentioned circuit for operating the alarm 444.

When the conversation between the combination alarm and telephone station 50 and the telephone substation C is terminated, the parties thereat. replace the receivers, of the telephone instruments thereat upon their respective switchhooks, thereby to interrupt the previously traced loop circuits, extending between the battery supply relays R426 and R421 and the telephone instrumentsat the station 50. and at the substation C, respectively, in order to cause the battery supply relays R426 and R421 tov restore. Upon restoring, the relay R421 recompletes at the contacts 428 the previously traced series circuit for illuminating the supervisory lamp L419 and for energizing the Winding of the control relay R455, thereby to. cause the last-mentioned relay to operate. Upon operating, the relay R455 come pletes, at the contacts 450, the previously mentioned circuit for operating the alarm 444, this circuit extending from ground by way of the contacts 459, the contacts 456 and the winding of the alarm 444 to battery. The illumination of the. supervisory lamp L419 and the operation of the alarm 444 indicate to the operator at the operator positionfifl that the party at the telephone substation C has replaced the receiver of the telephone instrument thereat upon its switchhook.

The operator at the operator position 60 may arrest the operation of the alarm 444 by reoperating the key K420 away from its normal position, thereby to complete the previously traced circuits for energizing the windings of the control relays R410, R480 and R458 in order to cause the last-mentioned relays to operate. Upon operating, the control relay R458 interrupts, at the contacts 459, the previously traced circuit for operating the alarm 444 and, upon operating, the control relays R410 and R480 complete the previously traced circuits for operative- 1y connecting the receiver 453 and the transmitter 454 to the: repeater 410 by way of the repeater 495 as previously explained. At this time, the operator at the operator position 60 may again converse with the party at the combination alarm and telephone station 50 in the event he has not replaced the receiver of the telephone instrument A thereat upon its switchhook.

In the event the operator at the operator position 60 wishesto rering the combination alarmand telephone station 50- in case the party thereat has replaced the receiver of the telephone instrument A upon its switchhook, the ringing key K405 is intermittently operated back and forth between its normal and off-normal positions. When the ringingkey K405 is operated to its off-normal position, a circuit is completed for projecting ringing current over the line N19 to the combination alarm and telephone station 50, this circuit extending from one terminal of a suitable source of alternating current supply by Way of the contacts 401' of the ringing key K405, to the plug tip 402 and from the other terminal of the source of alternating current BO-L supply by way of the contacts 409 of the ringing key K405 to the plug ring 403, the plug tip402 and the plug ring 403 being included in a circuit extending by way of theline [00 to the combination alarm and telephone station 50. The alternating current thus projected, over the line I00 to the station 50 causes the ringer thereat to be actuated in the event the receiver of the telephone instmmentA has been replaced upon its switchhook in the usual manner. I

In order competely to release the established connection between the combination alarm and telephone station 50 and the telephone substation C, the operator at the operator position '55 withdraws the plugs P ltl and P440 from the jacks J I20 and J445, respectively terminating the lines Hill and 153. When the plug 462 is withdrawn from the jack J 23, the previously tracedcircuit for energizing in series the upper winding of the ,for energizing the winding of the control relay R455 in order to cause the supervisoryflamp to be extinguished and the relay R455 to restore. Upon restoring, the answer relay 'RI3Il interrupts at the contacts 135 the previously traced'alternative circuits for energizing the lowerwinding of the impulse relay R145, prepares atthe con- .tacts I34 a point in the previously traced holding circuit forenergizing thewinding of the control relay RI 555 and completes at the contacts .I3I and at the contacts I32 the previously traced-circuit for energizing the windings of the impulse relay RME in series with the winding of the line relay RIM. The. impulse relay RI IE remains in its operated positionat this time. However, the line relay RIM remains restored, due to the high series resistance of the circuit forenergizing the winding thereof,.assuming that the partyat the combination alarm and telephone station 59 has closed the door 52 of the enclosing casing 5I thereat, thereby to operate the door switch SI I3 in order to interrupt at the contacts I I4 thereof:

the previously mentioned path for short-circuiting the resistor I08 as previously explained.-

In order to initiate an alarm on one of the combination alarm and telephone lines, the door of the enclosing casing at the associated station is opened and then the alarm switch thereat is operated. For'example, in order to initiate an alarm on the combination alarm and telephone line I60, theparty atthe combination alarm and telephone station 55 opens the door 52 of the enclosing casing 5i thereat,*thereby to cause the door switchSiIS to be operated in order to complete at-the contacts I'M thereof the previously mentioned path for short-circuiting the resistor I08. When the resistor i 38 is thus shortcircuited, the line'relay, RIM] and the control relay RI50 in the line circuit I89 individually associated with-the combination alarm and telephone line it operate'as previously explained, thereby to initiate a telephone calljon the line I and to cause the supervisory lamp LI 'M associated with the jack J I283 at the operator position 60 to be steadily illuminated. The party at the station 50 then operates. the alarm switch SII momentarily, thereby to-interrupt at the contacts H6 thereof the previously traced series circuit for energizing the winding of the line relay RIM and the windings of the-impulse relay RI45; Also, at the contacts II! of the alarm switch SI I5, there is completed a path for short-cir- ;cuiting the upper winding'of the impulse relay.

am, this path extendin from ground by way of the contacts I ll of the alarm switch SI.I5, the

contacts ,I I4 of the door switch SI I3, the winding Iil'lof the repeater I05, the contacts I I2 of the hookswitch SIII], Gilli, the contacts I3 I, CH5 and the upper winding of RIM to'ground. When the above-traced series circuit for energizing the windings of the impulse relay. RI45 is interrupted and the previously traced path for short-circuiting the upper winding of the impulse relay RME is completed, the impulse relay RI45 immediately restoresv to complete at the of the control relay Rliiii, this circuit extending from ground by way of the contacts I46, the

. contacts I46 a circuit for energizing the'winding 7 contacts I52, the winding of Rififi' anoLthe resistor I24 to battery. When energizedl over the above-traced circuit, the relay RISE operates to complete at the contacts I6I an. obvious holding circuit forenergizing the winding thereof inserieswith the resistor I24. It is noted that the alarm switch SI I5 at the combination alarm andoperates and the line relay RIM operates in the I event that it has restored, the control relay RI 50 remaining operated due to the completed holding circuit for energizing the winding thereof. Upon. reoperating, the impulse relay RI45 interrupts at the contacts I45 a point in the previously traced 5 original circuit for energizing the winding of'the.

, phone line IIIII by operating'the alarm switch SII5 regardless of whether the receiver of the telephone instrument A at the station 5t has been removed from its switchhook; In the event the, receiver of the telephone instrument A at the station 50 has been removed from its switchhook, operation of the alarm switch. SI I5 completes; at the contacts I" thereof, an alternative path for short-circuiting the upper winding of the impulse relay RI45, this circuitextending" from groundat. the contacts II! of the alarm switch SI I5, the

contacts III of thehookswitch'slm, CIM, the telephone instrument A,'CI03, C'II] I,'the contacts I3I, CH5 and the upper winding of the impulse relay RI to ground. Thus, the control relay,

RIBO is operated incident to the operation ofthe alarm switch SI I 5 regardless of whether the tele phone instrument B or the telephone instrument A is employed at the station to converse with the operator at the operator position 60.

Also, upon operating, the control relay RIBII interrupts at the contacts I63 the previously. traced circuit for illuminating'steadily the super:

visory lamp LIH associated with the jackJI2B at the operator position and completes at the contacts I62 a circuit for illuminating intermittently the supervisory lamp LI I4. The last-mentioned circuit extends from interrupted ground potential appearing'upon the control conductor CHO byway of the contacts I62 and the lampv LI I4 to'batte'ry. The flashing of the supervisory lamp LI'I4 associated withthe jack J I20 at the operator position 60 indicates to the operator thereat that an alarm conditionis present upon 40? control conductor CI'I3.'

the combination alarm and telephone line I00. Accordingly, the operator at the operator position 60 answers the call on the line I immediately and in preference to other ordinary telephone calls Waiting to be answered. The mode of answering the alarm call on'the line I00 at the operator position 60 is the same as that previously, explained. After the call has been answered at the operator position 60, the operator thereat may learn from the party at the comthe combination alarm and telephone line I00 completes at the contacts H54 and at the contacts I65 obvious paths for applying ground potential tothe start conductor CH2 and to the control conductor CI'II respectively. The application of ground potential to the start conductor CH2 and to the control conductor CI'lI initiates the operation of the finder sequence switch 304, thereby to cause the finder sequence switch 304 to select the particular finder switch 30I associated with the group or" 200 lines including the line I00 having the alarm condition thereon. Subsequently,the selected finder switch 3M operates to. select the line I00 in the associated group of 200 lines having the alarm condition thereon, whereupon the sender switch 3&5 operates to cause the recorder 30? to operate and make a record of the particular line I00 having the alarm condition thereon, thereby to identify the lastmentioned line. The sender sequence switch 306 causes the sender switch 305 to transmit the code to the recorder 301 a number of times; and thereafter thealarm recording equipment 300 is released and ground potential is applied to the The application of ground potential to the control conductor CH3 completes a path for shortcircuiting the winding of the control relay R160 inthe line circuit I80 individually associated with the combination al'armand telepho'neline I00."

This path extendsfrom the grounded control conductor Cl'l3'tofthe upper terminal of the winding of the relay RIM, the lower terminal of the winding of the relay RIM! having ground potential connected thereto as previously noted.

When the winding of the control relay RI60 is thus short-circuited, this relay restores'tointerrupt at the contacts I 6! a further point in the previously traced holding circuit for energizing the winding thereof, to interrupt at the contacts I62 the previously traced circuit for intermittently illuminating the supervisory lamp LI'M associated with the jack J I20 at the operator position 00, to prepare at the contacts I63 2. point in the previously traced circuit for steadily illuminating the supervisorylampLIM, and to inter-" rupt, at the contacts I64 and at the contacts I65, respectively, the previously mentioned paths for applying ground potential to the start conductor CI12and to the control conductor CHI. At this time, the line circuit I30 individually associated with the combination alarm and telephone line I00 occupies its usually operated position to-mark the line I00 as having a telephone call thereon. The line relay EH40, the impulse relay EMS and the control relay RI 50- occupy their operated positions at this time, as previouslynoted.

The line circuit individually associated with each of the combination alarm and .telepl'u ne= lines is so connected and arranged, that thesu pervisory lamp associated with the jack'terminating the line at the operator position 60 is illuminated in the event a fault appears upon the line. For example, the line circuit I80 individually associated. with the combination alarm and telephone line I00 is so connected and arranged that the supervisory lamp LI'M associated withthe jack J 5253 terminating. the line '00 at the operator position 60 is illuminated in the event the line I00 has an open circuit, a short circuit, or a ground circuit fault thereon. More particularly, in the event the line conductors CHM and CIO-2 of the combination alarm and telephone line I 00 are shorted together, an alternative circuit is completed for efiectively energizing the winding of the line relay RI40, this circuit extending from ground by way of the upper winding of the impulse relay RI45, CH5, the contacts I3l, CIOI, the short circuit between CI 0| and CI02, CI02, the contacts I32, the winding of the line relay RI40 andthe lower winding of the impulse relay RI45 to battery. When energized over the above-traced circuit, the line relay RI40 operates to complete at the contacts I the previously mentioned circuit for energizing the winding of the control relay RI50, thereby to cause the latter relay to operate. Upon operating, the control relay RI 50 completes, at the contacts I5I, the previously traced holding circuit for energizing the winding thereof, and completes at the contacts I54 the previously traced circuit for steadilyilluminating the supervisory lamp LIH associated with the jack J I20 at the operator position 60.

Also, in the event either one of the line condoctors CHM and CI02 of the combination alarm and telephone line I0li is broken, the previously traced circuit for energizingin series the upper and lower windings ofthe impulse relay R145 is interrupted, thereby to cause the latter relay to restore. Upon restoring, the impulse relay Rl lt completes at the contacts hit an alternative circuit for steadily illuminating the supervisory lamp LEM associated with the jack J I20 at-the operator position til. The last-mentioned circuit extends from ground by way of the contacts M6, the cont acts I53, the contacts I83 and the lamp L3!!! to battery.

= rthermore, in the event either the positive line conductor Cllli or the negative line conductor CI02 of the combination alarm and telephone line I 0i! is grounded, a circuit is completed for,

effectively energizing the winding of the line relay RMB. The last-mentioned circuit extends from battery by way of the lower winding of the impulse relay EH45, the winding of the line relay RMEI' and the contacts I32 to the line conductor Cl02. In the event the negative line conductor CW2 is grounded, the last-mentioned circuit is completed directly; and,in the event the positive line conductor CI M is grounded, the lastmentioned circuit is completed by way of the contacts 5- of the alarm switch SII5, the resistor I 08, the winding IElTI'of the repeater I05 and the contacts it?! either hookswitch SI II) to the grounded positive line conductor CHM. In either event the line relay Rl ill operates, thereby to cause the control relay R150 to operate and complete the previouslyxtraced circuit for steadily illuminating the supervisory lamp LIM associated with the jack J I 20 atthe operator position 60 as previously explained.

When the supervisory lamp L'Il i associated with the jack J l20at the. operator position 60 is illuminated; the operator thereat is advised u that a calling condition is present onthe combination alarm and telephone line 100, whereupon she inserts the plug P401 of the cord circuit in the operator position apparatus 400 into the jack J 120 as previously explained. Theoperator at the operator position 60 then operates the key K420, thereby operatively to associate the receiver ing order. The line 100 is testedby inserting the plug P201 of the test circuit 200 into the jack J and then manipulating the keys associated with the test circuit 200 in a manner more fully described hereinafter.

When the plug P201 of the test circuit 200 is inserted into the jack J120, a circuit is completed -forv energizing the winding of the answer relay R inlthe line circuit 180 individually associated with the combination alarm and telephone way of the resistor 205, the plug sleeve 204, the

jack sleeve 123, G110 and the winding of R130 to battery. When energized over the abovetraced circuit, the answer relay R130 operates to interrupt at the contacts 131 andat'the contacts 132 the previously traced circuit for energizing in series the winding of the line relay R and the windings of the impulse relay R145, and completes, at the contacts 133 and at the contacts 135, the previously traced circuit for energizing the winding of the line relay R140 in a reverse direction, thereby to cause the lastmentioned relay to restore; Also, the answer relay R130 completes at the contacts 135 the previously traced holding circuit for energizing the lower winding of the impulse relay R145. Accordingly, at this time, the answer relay R130 and the impulse relay R in the line circuit 180 occupy their operated positions while the line relay R140 and the control relay R in the line circuit 100 occupy their restored positions.

The operator at the operator position'60 checks the operation of the ammeter 206 included in the test circuit 200 by operating the key K215 away from its normal position in one direction, thereby to complete at the contacts 223 and at the contacts 225 of the key K215 a test circuit for the ammeter 200. This test circuit extends from ground by way of the contacts 225 of the key K215, the winding of the ammeter 206, the resistor 226 and the contacts 223 of the key K215 to battery. Assuming that the ammeter 206 registers properly, thekey K215 is returned to its normal position.

The operator at the operator position 60 then operates the key K20! away from its normal position, thereby to complete a circuit for testing the condition of the line circuit 180. More particularly, a circuit is completed for testing whether or not the line 100 has been freed of impedance elements including the winding of the line relay R140 and the lower winding of the impulse relay R145. This test circuit extends from ground by way of the contacts 209 of the key K201, the contacts 2H of the key K215, C230, the contacts 221 of the key K215, the contacts 224 of the key K215, the winding of the ammeter 206, the resistor 226, the contacts 222 of the key K215,

the contacts zis' of the key 215, c229,- the contacts 214 of the key K210, the plug ring 203 and the jack ring 122 to the negative line conductor C102 of the line 100. In the event the line 100 has been freed of impedance elements including the winding of the line relay R140 and the lower Winding of the impulse relay R145 due to the proper operation of the answer relay R140, no, potential appearsupon the negative line conductor 0102. Accordingly, the ammeter 206 does not register any current flowing over the above- I traced circuit. On the other hand, in the event the negative line conductor 0102 of the line 100 has not been freed of impedance elements including the winding of the line relay R140 and the lower winding of the impulse relay R145,

I due' to the improper operation of the answer relay R130, battery potential appears upon the negative line conductor C102 of the line 100, this battery potential being derived at the lower winding'of the impulse relay R145. Accordingly, the ammeter 200 registers a current flowing over the above-traced circuit, thereby to indicate to the operator at the operator: position 60 that the answer relay R130 in the line circuit has not operated to free the line 100 of impedance elements.

Assuming that the answer relay R130 in the line circuit 100 has operated properly as indicated, the operator at the operator position 60 then restores .thekey K201 to its normal position'and operates the key K215 away from its normal position in the opposite direction, thereby to complete at the contacts 216 of the key K215 a path extending from ground by wayof the contacts .216 of the key K215, the contacts 208 of the key K201 and the contacts 212 of the key K210 to the-plug tip 202 andto complete at the contacts 218 of the key K215 a path extending from battery by way of the'contacts 218 of the key K215, the contacts 222 of the key K215 and the resistor 226 to the negative terminal of the ammeter 205. When these paths are completed, the ammeter206 fails to register any current in the event either of the line conductors C101 and C102 of the line 100 is interrupted. Also, in the event the line conductors C101 and C102 of the line 100 are shorted together, the ammeter206 will register a high value of current. The circuit for causing theammeter 206 to register a high value of current extends from ground potential appearing on the plug tip 202 by way of the jack tip 121, G101, the shorted connection between C101 and C102, C102, the jack-ring 122, the plug ring 203, the contacts 214 of the key K210, the contacts 220 of the key K215 and the contacts 224 of the key K215 to the positive terminal of the ammeter 206.

' On the other hand, in the event either of the line conductors C101 and C102 of the line 100 is grounded, the ammeter'206 will read some value of current flowing over acircuit including the line conductors of the line 100. In the present instance, ground potential is connected by way of the previously traced path to the plug tip 202 and battery potential is connected by way of the previously traced path including the ammeter 206 to the plug ring 203. Accordingly, at this time, if the positive line conductor C101 of the line '100 is grounded, the ammeter 206 will register a low value of current due to the fact that the resistor 108 at the combination alarm and telephone station 50 is included in the previously traced connection between the'line conductors C101 and C102 of the line 100. On

the other hand, in the event the negative line conductor C582 of the line 100 is grounded, the ammeter will register a high value of current due to the fact that the resistor I08 at the comblnaticn alarm and telephone station 5!] is excluded from the circuit including the ammeter In the event the ammeter 206 registers either a high value or a low value of current, the key K258 is operated. Upon operating the key K2 til, ground potential is applied to the plug ring and battery potential is applied to the plug tip The path for applying ground poten-. tial to the plug ring extends from ground by way of the'contacts 2E6 of the key K2l5, the contacts 283 of the key K201 C223, and the contacts 2H3 of the key Ki Ill to the plug ring 293; and the path for applying battery potential to the plug tip ilii ex-tends from battery by way or the contacts are of the key K2! 5, the con- 222' of the key KZIE, the resister 226, the winding of the arnrneter 206, the contacts 224 of the key K2l5, the contacts 220 of the key C227 and the contacts 2H of the key KQlil to the plug tip 282.

With the key K249 operated, the ammeter 286 will register a high value of current in the event the positive line conductor CNl of the line I90 is grounded, due to the fact that the resistor I03 at th combination alarm and telephone station is excluded from the path including the winding of the arnmeter 2%; while the ammeter 266 will register alow value of current in the event that the negative line conductor C162 of the line lid? is grounded, clue to the fact that the resistor Hit at the combination alarm and telephone station is included in the path including the winding of the ammeter 2%. From the above, it w l be understood that, by operating the key Kfilli back and forth while the key K2I5 is operated in the opposite direction away from its normal position, the particular one of the line conductors Gilli or (H92 of the line N30 which is grounded may be determined by the operator at the operator position 60.

Assuming that one of the line conductors OH]! or Gilli. of the combination alarm and telephone line lfifi is grounded, the operator at the operator position fill first determines which one of the line conductors is grounded and then establishes a connection between the defective line H10 and one of the correcting circuits, such, for example, as the correcting circuit 245, by utilizing one of the patching cords, such, for example, as the, patching cord 23L First, theoperator at the operator position to inserts the plug P235 of the patching cord 2M into the jack J I29 and then inserts the plug 1 2% of the patching cord 23! into on of the jacks J 2418 or J 25! of the correct-- circuit M5 depending upon which one of the line conductors of the combination alarm and telephone line tilt is grounded. In the event the positive line conductor CH3! of the line I00 is grounded, the plug 2% of the patching cord 23! is inserted into the jack J25l. On the other .hand, in the event the negative line conductor Cltfi of the line llll is grounded, the plug 248 of the patching cord 235i is inserted into the jack J 2%.

Assuming that the negative line conductor CW2 .oi' the combination alarm and telephone line M8 is grounded, the plugs P235 and PZM] of they patching cord 23?! are inserted into the jacks J i and JZM, respectively. When the plug P245) is inserted into the jack J 246, an obvious path is completed at'the contacts 258 of the jackJZdfi for energizing the winding of the control relay R255, thereby to cause the latter relay to operate. Also, when the plug PEdfl. is inserted into the jack JZAB, a circuit is completed for energizing thev winding of the answer relay EH36 in the line circuit l8ll individually associated with the combination alarm and telephone line Hill. The last-mentioned circuit extends from ground by way of the contacts 285, the resistor 2M, C292, the jack sleeve 249, the plug sleeve t ll, C232, the plug sleeve 2.36, the jack sleeve l23, CH5 and the winding of RI to battery. Vfhen energized over the above-traced circuit, the answer relay Rite operates as previously explained, thereby to cause the impulse relay Rl lfi to remain in its operated position and the line relay Rl lll to restore. Upon restoring, the line relay Rldllinterrupts the previously traced circuit for energizing the winding of the control relay Rifill in the event the lastmentioned relay is operated. Accordingly, at this time the circuit for steadily illuminating the lamp LIM associated with the jack J l2d at the operator position is interrupted. Finally. when the plug P240 is inserted into the' jack J 2%, a circuit is completed for energizing the. winding of the control relay R21 B in the correcting circuit 265, this circuit extending from ground by way of the jack'ring 248, the plug ring 2 52, C233, the plug ring 237, the jack ring I22, CIGZ, the contacts MS of the alarm switch SH the resistor use, the winding ll of the repeater let, the contacts H2 of the hookswitch Sllll, cm, the jack tip till, the plug tip 238, G235, the plug tip M3, the jacktip 24?, the contacts 262, the contacts 166, the

contacts 2'57 and the winding of Bill? to battery.

It is noted'that direct ground potential at the jack ring M8 is applied to the grounded negative line conductor CW2 of the line iii!) and that the above-traced circuit for energizing the winding of the control relay R279 in the correcting circuit 245 includes the resistor its. Accordingly, the control relay R2!!! in the correcting circuit 245 does not operate at this time due to the high series resistance of the circuit for energizing 1c windingthereof.

At this time, the defective combination alarm and telephone line Hill has been operative by utilizing the correcting circuit 2&5, which circuit is utilized in connection with the line lliil until thenegative line conductor C95 2 of the line Hill is cleared of the grounding fault thereon.

At this time a telephone call may be initiated on the line lllfl in the usual manner by opening the door 52 of the enclosing casing El at the combination alarm and telephone station Ell as previously explained, thereby to complete at the contacts H4 of the door switch S1 l3 the previously mentioned pathfor short-circuiting the resistor I08. When the resistor M8 is thus short-circuitecl, the resistance of the previously traced circuit for energizing the winding of the control relay R210 is appreciably reduced, thereby to cause the lastmentioned relay to be effectively energized,

ing the-winding thereof by way of the grounded control conductor C233, prepares at the contacts 216 a further point in the previously mentioned circuit for energizing the winding of the control relay R280 and interrupts at the contacts 211 an obvious path for short-circuiting the resistor 213,

. 'ing the winding of the control relay R210.

thereby to cause the resistor 213 to be inserted in series in the previously'traced circuit for energiz- When the resistor 213 is inserted into the circuit for energizing the winding of the control relay R210, the last-mentioned relay remains in its operated condition. However, it is rendered extremely fast to restore in the event the circuit for energizing the winding thereof is momentarily interrupted. Also, upon operating, the control relay R215 completes at the contacts 218 a circuit for steadily illuminating the supervisory lamp L250 individually associated with the connecting circuit 245, this circuit extending from ground by way of the contacts 284, the contacts 218 and the lamp'L256 to battery. The steady illumination of the lamp L256 indicates to the operator at the operator position that a telephone call has been initiated on the combination alarm and telephone line associated with the correcting circuit 245.

The operator at the operator position 60 answers the call by inserting the plug P401 of the cord circuit in the operator position apparatus 400 into the jack J251. When the plug P104 is inserted into the jack J251, an obvious circuit is completed at the contacts 255 of the jack'li- 251 for energizing the winding of the control relay R230, thereby to cause the latter relay to operate. Upon operating, the control relay R2 50 interrupts at the contacts 264 a point in the previously traced holding circuit for energizing the winding of the control relay R215, thereby to cause the latter relay to restore and interrupt at the contacts 216 the previously traced circuit for steadily illuminating the supervisory lamp L256. Also, upon operating, the control relay R260 interrupts at the contacts 262 a point in the previously traced circuit for energizing the winding of the control relay R210, thereby to cause the latter relay to restore.

Also, when the plug P401 is inserted into the jack .1251, the repeater erator position apparatus 400 is operative associated with the repeater 105 at the combination alarm and telephone station 50, assuming that the key K420 has been operated away from its normal position. The circuit for operatively associating the repeaters 410 and 105 extends from ground by way of the jack ring 248, the plug ring 242, C233, the plug 122, G102, the contacts 116 of the alarm switch $115, the contacts 114 of the door switch $113, the winding 101 ofthe repeater 105, the contacts 112 of the hook switch S110, C101, the jack tip 121, the plug tip 238, C234, the plug tip 243, the jack tip 241, the jack ring 403, the contacts 408 of the ringing key K405 and the contacts 422 of the key K420 to the lower terminal of the winding 414 of the repeater 410 and from ground by way of the jack tip 252, the plug tip 402, the contacts 406 of the ringing key K405, and the contacts 421' of r the key K420 to the upper terminal of the winding-413 of the repeater 412.

answers the call as previously described, the call may be extended to one of the telephone. substations as previously explained. In order to upon operating,

' eratively associated 410 included in the opring 231, the jack ring 3 253, the plug ring After the operator at the operator position 60 extend the call to one of the telephone stations, the key K415 is operated, thereby to cause the control relay R435 to operate as previously noted. Upon operating, the relay R435 completes at the contacts 438 a holdlng'circuit for energizing the upper winding thereof in series with the winding of the answer relay R in the line circuit 180. The last-mentioned circuit extends from ground by way of the upper winding of the relay R435, the contacts 438, the plug sleeves 404, the jack sleeve 254, the jack sleeve 249, thepiug sleeve 241, C232, the plug sleeve 236,. the jack sleeve 123, C116 and the winding of R130 to battery. Also, the control relay R435 completes at the contacts 431 a loop circuit for supplying battery current to the common battery telephone instrument A at the combination alarm and telephone station 50, this circuit extending from the grounded line conductor C102 of the line 100 by way of the contacts 116 of the alarm switch S115, the contacts 111 of the hookswitchSllO, C104, the telephone instrument A, C103, C101,

the jack tip 121, theplug-tip 238, C234, the plug tip 243, the jack tip 241, the jack ring 253, the plug ring 403, the contacts 408 of the ringing key K405, the contacts 431 and the lower winding. of R426 to battery. The extension of the connection over the telephone line extending to the telephone substation, and the release of the established connection between the telephone substation and the combination alarm and telephone station 50 are the same as those previously explained.

Furthermore, it is noted that an alarm may be initiated on the combination alarm and telephone line 100 at the combination alarm' and telephone station 50 while the line 100 is opwith the correcting circuit 245 as previously explained. At this time, the answer relay R130 and the impulse relay R in the line circuit individually associated with the combination alarm and telephone line 100 occupy their operated positions. Also,- when the answer relay R130 operates, it completes at the contacts 136 an obvious circuit for energizing the control relay R100 in the line circuit 180, thereby .to cause the latter relay to operate. Furthermore, the answer relay R130 interrupts at the contacts 131 a point in a circuit, traced hereinafter, for energizing the winding of the control relay R in the line circuit 180. At this time, only the control relay R265 in the correcting circuit 245 occupies its operated position.

' When the party at the combination alarm and telephone set 50 opens the door of the enclosing .casing thereat, the previously traced circuit for effectively energizing the winding of the control relay R210 in the correcting circuit 245 is completed, thereby to' cause the latter relay' to operate and complete the previously traced circuit for energizing thewinding of the control relay R215. The control relay R215 then operates as previously explained. The party at the combination alarm: and telephone station. 50 then momentarily operates the alarm switch S115 as previously explained, thereby to interrupt at the contacts 116 thereof the previously traced circuit for energizing the windingof the control relay R210, whereupon the latter relay restores. Upon restoring, the. relay R210 completes, at the contacts 211, the previously mentioned circuit for energizing the winding of the control relay R280, this'circuit extending from the grounded control conductor C293, by way of Iii the contacts 27!, the contacts Zi'fi and the Winding of R286] to battery. When energized over the above-traced circuit, the relay R288 operates to complete at the contacts an obvious holding circuit for energizing the winding thereof by way of the grounded control conductor C293 and interrupts at the contacts a point in the previously traced circuit for steadily illuminat ing the lamp L256. Also relay comlctes at the contactsfiSt, a circuit for'intermittently illuminating the supervisory lamp L256, this circuit extending from interrupted ground potential appearing. upon the control conductor C25? by way of the contacts the contacts E'idand the lamp L255; to battery. Tie flashing of the supervisory lamp L256 indicates to the operator at the operator position that the combination alarm and .c ephone line atively associated with the correcting circuit 245 has an alarm condition thereon. Also, upon. operating, the control relay R5283 interrupts at. the contacts 286- a point in the previously traced circuit for energizing the winding of the answer relay R133 in the line circuit its indiviclually associated with the combination alarm and telephone line iilll, thereby to cause the latter relay to restore. Further, the relayR/lfiil prepares at the contacts 2% a point an alternative circuit, traced hereinafter, for en rgizing the winding of the answer relay RlZil and completes atthe, contacts 282 an obvious circuit for energizing the winding of the control relay R293. Shortly after the winding of the control relay R299 is energized over the previously mentioned circuit, this relay operates, as it is'of the slowto-operate type, and completes at the contacts 295 the previously mentioned alternative circuit for energizing the winding of the answer relay R538. The last-mentioned circuit extends from ground by way of the contacts the contacts 29L the resistor 244, the jack sleeve 2%, the plug sleeve 24!, C232, the plug sleeve the jack sleeve 123, CH6 andthe winding of R838 to battery. When energized over the above-traced circuit, the answer relay- Riilil reoperates.

From the foregoing it is apparent that, incident to the operation of the alarm switch Sl H5 at the combination alarm and telephone station 55, the correcting circuit operatively associated' with the alarm and. telephone line its causes the answer relay 'Rlfifi in the line circuit lflll to restore and then reoperate. When the answer relay Ri3ll restores, it completes at the contacts it? the previously for energizing the Rlllll, this circuit winding the control relay extending from ground by way of the contacts i371, the contacts llll and.

the winding of EH35 to battery. When gized over the above-traced circuit, the EH35 operates to prepare at the contacts point in a circuit, traced hereinafter, for energizing the winding of the control relay Rita. When the answer relay reoperates, cornpletes, at the contacts i553, the previously mentioned circuit for energizing the winding of the control relay Rltil, this circuit extending from ground by way of the contacts itii, the contacts I92, the contacts 138, the winding of Rial] and the resistor 32 3 to battery. when energized over the above-traced circuit, the relay Riot? ope ates and completes at the contacts lei the previously traced holding circuit for energizing winding thereof. Furthermore, upon operating, the relay Rlfiil causes the alarm recording equipment 383 to be operated, whereupon the recorder enerrelay Hill a mentioned circuit is operated to make a record identifying the combination alarm and telephone line I having an alarm condition thereon as previously explained.

It is noted that the control relays Rl85 and Bi are or" the slow-to-release type. Accordingly, these relays remain operated during the time interval requir d for the answer relay R130 to restore and again reoperate, due to the fact that this time interval is very short. Shortly after the answer relay REM reoperates, the control relay Bl restores as the circuit for energizing the winding thereof is interrupted at the 93's, upon reoperation of the answer y Rllll. Upon restoring, the control relay Ptltii interrupts at the contacts I86 the previously traced original circuit for energizing the winding the control relay REG-ii. The operator at the operator position 6i] then answers the call by inserting the plug Pill! of the cord circuit in the operator position apparatus 408 into the jack. JEN as previously explained. When the plug is inserted into the jack J25I, the previously traced circuit for energizing the winding of the control relay R2533 is completed, thereby to cause the last-mentioned relay to operate and remove ground potential from the conductor When ground potential is removed from the control conductor C293, the previously traced holding circuits for energizing the windings of the control relays Elland R255 are interrupted, thereby. to cause the latter relays to Upon restoring, the control relay R280 recomp le-tee at the contacts 266 the original circuit for energizing the winding of the answer relay thereby to prevent the last-mentioned relay from restoring at this time. Also, upon restoring, t..e control relay R280 interrupts, at the contacts the previously mentioned circuit for energizing the winding of the control relayRlQil, thereby to cause the latter relay to restore. Upon restoring, the control relay R2l5 interrupts the contacts 218 the previously traced cii uit for illuminating the supervisory lamp Lil In order to release the established connection between the combination alarm and telephone station 5!? and the operator position as, the operator thereat withdraws the plug Paul from the jack J25! as previously explained.

It is noted that, when the combination alarm and telephone line 5953 has been cleared of faults, the connection between this line and the correcting circuit ti t-E5 is interrupted by withdrawing the plugs and Phil? of the patching cord 23! from the respective jacks J 520 and JMS. When the plug is withdrawn from the jack J l 20, the previously traced circuit for energizing the i ding of the answer relay RISE is interrupted, thereby to cause the latter relay to restore. Upon estoring, the answer relay R539 completes at e contacts 63? the previously traced circuit or energizing the winding of the control relay thereby to cause the latter relay to operate while the control relay RiQ'd occupies its operated position. Shortly thereafter, the control relay restores and interrupts at the contacts till the previously traced circuit for energizing the winding of the control relay EH55, whereupon the last-mentioned relay restores shortly thereafter. Accordingly, the removal of the P235 from the jack J12!) does not cause the control relay Rite in the line circuit I80 to operate atthis time.

.In; the foregoing. description of the operation of the'co-rrecting circuit 245 in conjunction with thedefective combination alarm and telephoneline I00, the'plug P240 of the patching,

cord 23! was inserted into the jack J246 due l to the fact that it was assumed that the ne'ga- I tive lin'e conductor C102 of the line lllii had a ground fault thereon. In the event the positive linecon'duotor 'Clill of the combination alarm and telephone line Hill had a ground fault thereon, the plug P240, of the patching cord 23! would the operations .of the correcting'circuit 245 in conjunction with the combination alarm and telephone line 100 under these conditions are omitted.

iwhilethere has been described what is at present considered to be the preferred embodiment of the invention, it will be understoodthat various modifications may be made therein', and-i it isintended to cover in the appended-claims all such' odificationsas fall within the spirit and; scope of the invention. I

What is claimed isr Y 1'; In a telephone system, a station provided with an enclosing casing having a door, a line the H tending to said station and connected to a source f 'of current-telephone apparatus housed in said casing, a" resistor 'atsaid station, said telephone apparatusandsaid resistor being normally con? nected in series circuit relationship in said line,

the resistance of saidresistor'being'so propor-" tioned that said telephone apparatus is normally effectively 'deenergi'zed; a switch at said station operativeto reduce the effective resistance of said resistor, thereby efieotively to energize said telephone apparatus, means controlled when the efiective resistance of said {resistor is reduced "for initiating a telephone call on said line, and means controlled by the door 'of "said casing forfoper atin'g said switch. i

, 2. In a telephone system; a station provided with an enclosing casing having a door, a line extending to said station and connected to a source of current, a repeater and a resistor at said station, said repeater and said resistor being,nor-' mally connected in series circuit relationship .in said line, the resistance'ofsaid resistor being so proportioned that said repeater is normally effectivelydeenergized, a telephone instrument housed in said; casing and toperativelyfassociated with said repeater,='a"switch at said station operative to'-short-circui't said resistor, thereby effectively to energize said repeatenmeanscontrolled when j said resistor is 'short-circuited for initiating a telephone call on said line, and means controlled by the door of said casing for operating said a switch. i i v 3 In a telephone system, a station provided with an enclosing casing having a door, a line extending to said station and connected to a source of current, a repeater at said station normallyoperatively disassociated from said line, a first telephone instrument of th'esound-powered type housed in said casing and operatively associated with said repeater, a secondtelephone instrument of the common battery type housed in said casing and normally operatively disassociated from true ' mitting a said lin e, means controlled by the door of said casing for operatively associating said repeater with said line, means including a hook switch housed in said casingfor operatively associating said second telephone instrument with said line,

and means controlled when said repeater or said second telephone instrument is operatively associated with said line for initiating a telephone call on said line.

i. In a telephone system, a station provided" with an enclosing casing having a door, a line ex tending to said stationan'd connected to a source of current, a repeaterat'said station 'provi'ded with first andsecond windings, a first telephone instrument of the sound-poweredtype housed in said casing and loperatively associated with the first windingof said. repeater, the second winding of said 'iepeater being normally operatively dis- 'associated from said line, a second telephone instr'ument of thecommonlbattery typehoused in said casing andnormally'operatively disassooiated from said line, means controlled when the door of said casing is opened for operatively associatingthe second winding/of said repeater with said line, 'means including'a hookswitch housed in 1 said casing and" operative to short-circuit the second winding of said repeater and operatively to associate said second telephone instrument with said line, and means controlled when the second" winding of said repeater or said second telephone instrument is' operatively associated with said line for initiating a telephone callon said line.- -5;Inasignalingsystem, a station, an operator position, aline extendingbetween said station and said operator position and connected to a source or current, telephone apparatus at said station and adapted-tobe'operati'vely associated with said line, answering apparatus'at said operator position jandadapted to be operatively' associated'with said linie, a line'cir'cuit associated with said line andincluding' first and second relays, a resistor at said" station, said-first'relay, said second relay" and'saidresistor being connected in series circuit relationship jinsaid, line, said first relay being normally operated and said second relay being normallyrestored, means at said station for reducingthe effectiveresistance of said resistor,

therebyto cause said "second relay to operate,

I'neansat said station for. interrupting said line,

thereby to cause said first relay to restore, means responsive-to the restorationof said first relay orthe operation ofsaid second relay for trans I first-signal to said operator position,

and means responsive to the restoration of said first relay'following the operation of said second relay for transmitting'a second signal tosaid operator position.

6, Ina telephone. system, a station provided"- with an enclosing casing having a door, a line extending to saidstation and connected to a source of'current; telephone apparatushoused in said casing'and adapt'edto-b'e operatively associated wit said line, answering apparatus at said operator position andadapted to be operatively associated with said line', 'a line circuitassociated-with said line and including first and second relays,

ares istor at said station, said first relay, said sec' 0nd relay and said resistor being connected in series circuit relationship in said line, said first relaybeing normallyoperated and said' second relay being normally restored, means controlled by' the door of said casing for reducingthe efiective resistance ofsaid resiston-thereby to cause said 'second relayto operate, 'means including a device housed in said casing for'interru'pting said line, thereby to cause said first relay to restore, means responsive to the restoration of said. first relay or the operation of said second relay for transmitting a first signal to said operator position, and means responsive to the restoration of said first relay following the operation of said second relay for transmitting a second'signal to said operator position.

'7. In a signaling system, a station, an operator position, a line extending between said station and said operator position and connected to a source of currentytelephone apparatus at said station and adapted to be operatively associated with said line, answering apparatus at said operator position and adapted to be operatively as sociated with said line, a line circuit associated withsaid line and including first and, second relays, a resistor at said station, said first relay, said second relay and said resistor being connected in series circuit relationship in said line, said first relay being .normally operated and said second relay being normally restored, means at said'station for reducing the effective resistance of said resistor, thereby to cause said second relay to operate, means at'said station for interrupting said line, thereby to cause said'first relay to restore, means responsive to the operation.

of said second relay for initiating a telephone call on said line, and means responsive to the restoration of said first relay following the operation of said second relay for initiating an alarm on'said line.

8. In a signaling system, a station, an operator position, a line extending between said station and said operator position, said line being subjected to ground faults, telephone apparatus at said station an'd'adapted to be operatively associated with said line, means at said station for initiating a telephone call on said line, means at said station for initiating an alarm on said line,-

a line circuit normally associated with'said line,

a correcting circuit adapted to be associatedwith said line when said line has a ground fault there'- on, means controlled: from said operator position for disassociatingsaid line circuit from said line and for associating said correcting circuit withsaid line, means included in-each of said circuits and responsive to thepresence' of a telephone call on said line when the circuit is associated therewith for transmitting a first signal to said operator position, and means included in each of said circuits and responsive to the presenceof an alarm on said line when the circuit is associated therewith for transmitting a second signal to said operator position.

9. In a signaling system, a station, an operator position, a line extending between said station and said operator position, saidline being subjected to ground faults, telephone apparatus at said station and adapted to beoperatively associated; with said line, means at said station for initiating a telephone call on said line, means at said station for initiating an. alarmon said line, a line circuit normally associated with said line, a correcting circuit adapted to be associated with said line when said line has aground fault there'- on, means controlled from said operator position for disassociating said line circuit from said line and for associating said correcting circuit with i said line, means included in each of said circuits and responsive to the presence of a telephone call on said line when the circuit is associated thereline, and means includedin each of said circuits and. responsive to the presence of analarm on" at said station for initiating an alarm on said line, a line circuit normally associated with said line, a correcting circuit adapted to be associated with said line when said line'has a ground fault thereon, means controlled from said operator position for disassociating said line circuit from said. line and for associating said correcting circuit with said line, a relay, means included in each of said circuits and responsive to the presence of an alarm on said line when the circuit is associated therewith for controlling the operation of said relay, means operative toidentify saidline, and means including said relay for controlling the operation of said last-mentioned means. i r

111. In'a signaling system, a station provided with an enclosing casing having a door, an

operator position; a line extending, between said' station and said operator position, said, line being'subjected' to ground faults,'telephone apparatus housed in said casing and adapted to be 'operatively associated with said line, a device housed in said casing, a line circuit normally I associated with said line, a correcting circuit adapted to be associated with said line when said line has a ground fault thereon, means controlled from said operator position for disassociating said line circuit from said line and for associating said correcting circuit with said line, a relay,

means included in each of said circuitsand responsive to the opening of the door ofsaid casing and thesubsequent operation of'said device when the circuitis associated with said line for controlling the operation of said relay, means operative to identify said line, and means including said relay for controlling the operation of said lastrmentioned' means. v

12. In a signaling system, a station provided with an enclosing casing having'a door, an operator position, a line extending between said station and said operator position, said line being subjected to ground. faults, telephone apparatus housed in said casing and adapted to 'be operatively associated with'saidline, a device housed insaid: casing, a line circuit normally associated with said line, a correcting circuit adapted to be 7 associated with said line when said line has a ground fault thereon, means controlled from said operator position for disassociatingsaid line circuit from said-line and for associating said corrooting circuit with said line; a relay individual vto said line, means included in each of said circuits and responsive to the opening of the door of said casing and the subsequent operation of said device when. the circuit is associated with said line for causing: said relay to operate, means operative to identify said line, and means responsive to the operation of said relay for marking said line'to be identified and for controlling the operation of said last-mentioned means.

CLARENCE E. LOMAX. CHARLES F; F'FOLLIO'I'T.

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