Патент USA US2410866код для вставки
Nov. l2, 1946. 2,410,866 K. L. BURGENER TELEPHONE SYSTEM Filed April 17, 1944 2 Sheets-Sheet 1 INVENTÜR. KARL L. BURGENER ¿25X ¿W4 _ATToR NEY Nov. 12, 1946. K. L. BURGENER ' 2,410,866 -TELEPHONE SYSTEM Filed April 17, 1944 2 VSheets-Sheet 2 n w. m Ow N9. . INVENTOR. KARL L. BURGENER 2,410,866 Patented Nov. 12, 1946 Tuur ori-‘ICE UiiiilTED 2,410,866 rnLEr'noNE SYSTEM Karl L. Burgener, Villa Park,A Ill., assignor to Automatic Electric Laboratories, Inc., Chicago, lill., a corporation of Delaware Application April 17, 1944, Serial No. 531,389 `19 Claims. (Cl. 179-84) 1 The present invention relates to telephone sys tems in general, and more particularly to im iting factor being the presence of the called party on the line. The uniformity of quick ringing cut-off on party lines is accomplished by adjusting the re sistance Value of the local, or holding, circuit of ing cut-olf in manual and automatic telephone Ul the combined ringing and ringing cut-off relay in switchboards. ` direct relationship to the frequency of ringing An object of the inventon is to provide new current used in each instance. Each frequency and novel circuit arrangements for applying and of ringing current is allocated a certain resist disconnecting >automatically-interrupted ringing ance value for `the holding circuit of the relay. currents to vand from arplurality of connecting For example, a greater1 resistance value is inserted circuits in a telephone system. , in the holding circuit of therrelay when L'iO-cycle Another object of the invention is to provide ringingl current is selected than when the ring new and novel circuit arrangements to enable a ing current is iii-cycles, in order to accomplishH called party, when answering a call, to out oil an equivalent quick ringing cut-off. These ad quickly the ringing current during either the ring ` justed resistance values enable the combinedl ‘ ing or silent periods, and to provide inY these _ar ringing and ringing cut-off relay to perform uni- l rangements a greater margin of operation over formly and emciently over the entire range of more severe subscriber line circuit conditions than ringing current frequencies. is possible with» the present practice,- cf ringing A feature of the invention is that the resistance cut-off relay operation. For example, in a tele 20 value of the holding circuit of the combined ring phone system employing party lines, a greater ing and `ringing cut-off relay is varied by means number of substation ringers may be bridged of compensating resistances connected in series across a line of higher loop resistance and lower with the holding winding of the relay, the proper insulation resistance with the ringing cut-off resistance value being selected automatically _at method provided in the invention than with any 25 the time the required frequency of ringing cur other system cf quick ringing cut-off known to rent for signalling the desired called party is se the art. ` lected. A further object of the invention is to provide Another feature of the _invention is that theV uniform quick ringing cut-off with all frequencies greater Vmarginv of operation» for the combined of ringing current, when party-line ringing is 30 ringing and ringing cut-olf relay obtained in the employed, in order that the ringing cut-off be manner described inthe preceding paragraph, practically instantaneous regardless of the fre provides for quicker ringing cut-off withv any fre proved circuits for automatic individual-line ring ing, automatic party-line ringing, and quick ring quency of ringing current which may be used for quency of ringing current on a short line of signalling the called substation. Under the pre relatively low resistance than with any other sys vailing circumstances of the art, ringing cut-off 35 tem of quick ringing cut-off relay operation. is relatively much slower with the higher fre Damage to the transmitter of the answering tele quencies of ringing current than with the lower phone on a low resistance line, where the ringing frequencies. `The invention includes new and current flow is obviously relatively large, is, there novel means for overcoming this inequality of fore, minimized because the ringing cut-off is ringing cut-off, thereby providing for uniform 40 -practically instantaneous when the handsetof quick ringing cut-off over` the entire range of the answering telephone is lifted during a ring ringing current frequencies. ì . ing period. ‘ In- order to accomplish the above described Anotherv feature of the invention is that the objects, the invention combines the control of the adjusting of the resistance value of the holding ringing application and the ringing cut-olf func 45 circuit of the combined ringing’ andr ringing cut tions t'o- one relay. This combined ringing and loff relay in direct relationship to the frequency of ringing cut-off relay operates overA a local circuit the ringing current used tosignal the called sub to supply ringing current to the selected line, and station, enables the power inthe holding winding releases to, disconnect the ringing current from of the combined ringing and ringing cut-off relay 50 the line when the called party answers. In addi ' to offset; or neutralize, the additive eiîect of the tion, when the connection is kcompleted by an alternating ringing , current during the periods operator, means are provided so that the operato-r when the alternating current in the line winding starts or restarts the automatic ringing as inde of the relay is i'n Athe direction to aid the super pendent> operations entirely dissociated“ from any imposed direct current in the line winding' of the 55 means for selecting the called line,v the only lim 3 2,410,866 relay. Hence, the power in the line winding of the relay does not overcome the power in the holding winding at any period and cause the relay to remain operated and continue to send ringing current out on the line after the called Darty has answered. Quick ringing cut-olf is thus as sured with any frequency of ringing current. There are other objects and features of the invention havingI to do for the most part with the circuit details involved in carrying out the foregoing. The various objects and features of the in vention will be understood best upon a further perusal of the description in connection with the accompanying drawings, comprising Figs. l and 2, showing by means of the usual circuit dia grams so much of the apparatus in a telephone system embodying the features of the invention as are necessary to an understanding of the same. Referring now to the drawings, Fig. 1 illus strates a cord circuit of a manual telephone switchboard utilizing the present invention. The invention may, 0f course, be applied to any well known type of cord circuit equipped to perform any combination of well-known functions asso ciated with a manual telephone switchboard. 4 pose of reducing possible shocks t0 the operator in the handling of the plug. When a call is received at the jack JI over a local battery line instead of a common batteiy line, sleeve relay Il of the cord circuit does not operate when the plug PI is inserted into jack J I because the resistance of relay I0 is sufficiently high to prevent the operation of sleeve relay |'|. The lower winding of relay |2, therefore, re mains connected to the windings of the repeat ing coil at contact I8, and relay I6 is not con nected to the repeating coil. Consequently, no transmission battery is supplied to the calling line. time. Relay I2 performs no function at this ~ Having inserted the plug PI into jack J I, the operator throws the talk key of the cord cir cuit in order to converse with the calling party. The operation of the talk key closes the circuit 20 of splitting relay 29, the operation of which di vides the cord circuit into two sections in the well-known manner, and extends both sections to the operator common position circuit shown in Fig. 2. The tip and ring of the answering plug PI are connected to the common position cir cuit inductively through the windings of the re peating coil and then via the upper and lower tion equipment common to all of the cord cir front contacts of relay 29 and conductors 00 and cuits of the switchboard, including the various keys, relays and operator telephone set. It is 30 6I. The operator telephone set shown at the left on Fig, 2 is, therefore, connected to the an understood that the common position equipment swering plug P| via contact |01 of relay |04, may be of any well known type, with common key upper winding of operator induction coil, contact functions such as are shown on Fig. 2 of Crocker |05 of relay |04, contact I| 2 of cut-off answer Patent 1,771,842 and described in the associated key and conductor 60 for the tip side; and via specification. contact |0| of relay |04, lowerwinding of op The invention having been described generally, erator induction coil, contact |02 of relay'I04, a detailed operation of the apparatus shown will contact |08 of cut-off answer key and conductor now be given. For this purpose, it will be as 8| for the ring side. The operator may now ob sumed that the operator receives a call over a the number of the desired station from the line circuit represented by jack J | on Fig. 1. 40 tain calling party. This line circuit may be of any well-known con The operation of splitting relay 29 also switches ventional type either common battery or local the calling section of the cord circuit, including battery, the difference with respect to the cord the sleeve conductor of calling plug P2 and the circuit being in the resistance value of relay I0 associated sleeve relay 40, to the common position connected to the sleeve spring of jack J I , If circuit shown in Fig. 2, but these switchings per the subscriber line is of the common battery type, form no functions at this time. The resistance the resistance value of relay I0 will be relatively coil wired in multiple with the winding of relay low, and if the subscriber line circuit is of the 29 provides spark protection for the Contact of local battery type, the resistance value of relay the talk key. |0 will be relatively high, The purpose of the 50 Having ascertained the number of the desired differences in resistance values of relay I0 is to line, the operator restores the talk key to normal operate certain relays in the cord circuit when and then inserts calling plug P2 into jack J2 the line circuit is of the common battery type, which is assumed represents the desired line. As and to prevent the operation of certain relays in in the case of the line circuit connected to jack the cord circuit when the line circuit is of the J |, the line circuit connected to jack J2 may also local battery type. be of either the common battery or local battery Assuming that the operator has received a call _ type, and the resistance value of relay 48 connect over a common battery line, the operator inserts ed to the sleeve spring of jack J2 will be corre the answering plug PI of an idle cord circuit into spondingly low or high. jack J i. When the plug PI enters the jack J |, The restoration of the talk key to normal posi the relay |`| of the cord circuit is energized tion releases the splitting relay 29, and the re through the sleeve of the plug and the jack and storing of relay 29 disconnects the common posi relay I0. Relay |'| operates, disconnects relay tion circuit from the answering and calling sec |2 from the repeating coil at contact I8, and connects the windings of relay Iâ to the tip and 65 tions of the cord circuit, and re-establishes the Fig. 2, when placed below Fig. 1, shows posi ring conductors of the calling line through wind ings of the repeating coil. Relay I'I also closes the circuit of the answering, cord supervisory lamp momentarily at its upper front contact. Relay transmission circuit between the answering and calling-sections of the cord circuit. Relay 29 also re-connects the sleeve of the calling plug P2 to the sleeve relay 40. , The cord circuit is equipped with a tip- busy I6, however, operates through the calling party 70 test and, consequently, in case the line circuit is telephone loop to open the answering cord super of the multiple jack type, the operator may make visory lamp circuit at a back contact. Relay I6 also supplies transmission battery to the calling party. The resistance coil which is wired in mul tiple with the winding of relay I 1 is for the pur the conventional tip busy test before inserting the calling plug P2 into jack J2. The tip busy test circuit may be traced from the sleeve of jack J2, n 75 tip of calling plug P2, contact 46 of ringing call 2,410,866l key, contact 42 of relay 40, conductor 53 to the common position circuit shown in Fig. 2, upper right-hand winding of theA monitor and busy test coil toposi-ti-ve battery, and inductively to the cor responding upper left-hand winding of t‘n'e moni 5 tor and busy test coil to the operator’s receiver. The lower right-hand winding oi the monitor and busy test coil is extended along by means of con ductor 53, said conductor 59 being twisted into a pair with conductor 58 to obtain a balance so thatv 10.l the busy test clicks will not be introduced indue tively into other cord circuits. Conductor 59 is not connected to the cord circuit. Assuming that the selected line isv of the». com mon battery type, sleeve relay 43' is, energized, when the calling plug P2 is inserted'. into jack J2, through the sleeves of the jack and the plug and the center back contact of relay 29. The opera-q tion of sleeve relay 4i] causes sleeve relay I9 to op erate through contact 3B, as sleeve relay> i9 is of such resistance that it will operate from the rela» tively low resistance of relay 48 in multiple with ductor of'calling plug P2. The desired «telephone ‘ on the plugged-up line is, therefore, rung.- auto' matically-until either the called station answers or the Ycalling partyv abandons the call.. Ring back tcne is supplied to the calling party through the small-capacity condenser bridged around contact 3l of relay 33. The combined ringing and ringing cut-oir relay 33: remains operated duringr the automatic signalling oi thecalledv sta tionV because the circuit- of the direct-current component of the ringing current through' the line winding of relay 33 is> not closed@ until the» called party lifts the hand-setfrom the telephoneA cradle. The operation of the combinedi ringing andk ringing cut-off relay 33 also opens the calling." cord supervisory lamp- at Contact 31 thus giving the operator ringing supervision, well-known as “dark keyshelf,” to indicate that the operator’s work on this connection has been completedlun til disconnect supervision is received. Disconnect» supervision will be received when the calling and called parties have completed their conversation the winding of sleeve relay 4D. Sleeve relay 40 and reutrneol. their handsets> to the respective opens the tip busy test circuit at contact 42, and cradles. 25 extends the tip conductor through contact 4l to When the calledï party answers, the circuit‘o'f the combined ringing and ringing cut-off relay 33. the direct current through the lower, or line, Sleeve relay la disconnects relay 23 at contact winding of the combined ringing and ringing cut 23, connects the transmission battery feed relay oiï relay 33 is closed through the telephone loop. 23 to the inside terminals of the calling half of This direct current in the line winding neutralizes-the repeating coil, extends ground potential from 30 the direct current in the holding winding: of' re-` the front contact of relay l5, contact 2l of relay lay 33 and relay 33 restores to normal, removing i3 to contact 24 of relay 23, and completes the ringing current from the line and» extending the circuit of the calling'cord supervisory lamp from tip and `ring conductors ofîtlie calling plug P25 to contact 22 through contact 31 of relay 33 and the the repeating coil. Relay 231 operates onv the 35 upper back contact of relay 23. „ called party loop to supply transmission battery, Assuming that the desired telephone connected and' also opens the calling cordI supervisory lamp. to jackJZ is-to be signalled with the, ringing fre circuit at its upper back contact, thusl retaining quency> 2, the operator depresses momentarily the the “dark keyshelf.” The transmission circuit ringing key 55 all the way down, and the ringing between thev calling and called 4parties is corn key 55 will return tok and remain in the ringing pleted induotively through the windings of the position, in the well-known manner, with its back repeating coil. contacts openand the front contacts closed. The If the called party should disconnect prema iirst action of the downward stroke of key 55 turely and the calling party requests thevopera automatically restores any of the keys 53, 54, or tor to reestablish the connection, the operator 5E which maybe in the ringing position, and then 45 may restart the ringing on the called line by de contact 51 is operated at the bottom of the down pressing ringing keyv 55 all- the way Adown mo ward stroke. it is understood that the four keys mentarily, and relay 33 will again operate and 53, 54, 55 and 5G and the common contact 51 are lock up and reconnect ringing current to the tip mounted on one escutchecn and interlocked by and ring. conductors of calling plug P2.` AIt is means of a ladder releasing mechanism in the 50 unnecessary for vthe operator to request there well-known manner so that only one key~may be quired. frequency Ifor the rering,.as the ringing in the ringing position at one time. key used` for the original ringing will remain in The selection of frequency 2 by the operator de the ringing position (partly depressed) until later pressing ringing, button 55, causes the combined released by the depression of ringingk key button ringing and ringing cut-off relayA 33 to operate 55 53, 54, or |56 ona new call. from ground potential, front contact of relayV l5, When> a connection requires the use of fre. contact 2l of relay I9, contact 24 of relay 23, con quency 5, the operator’s ringing routine. is tact 51 oi the ringing key, upper winding of relay changed somewhat since there are only four ring 33 to negative battery, andl to lock up from ground ing key buttons on the ringing key assembly- corn potential, front contact of relay l5, contact 2l of 60 prising keysY 53, 54, 55 and 56. The lever type relay I9, contact 24 of relay 23, upper back contact ringing call key associated with the calling plug of ringing key 53, upper front contact of ringing P2 is used for ringing the called linewith fre keyy 55, compensating resistances 5l and 52 in se quency 5, and is mechanically associated with ries, contact 33 of relay 33, upper winding of relay the button> type ringing keys 53, Á54, 55 and 56 inA 65 33 to negative battery; suchl a well-known manner that when theV lever The operation of the combined ringing and type ringing call key is operated, any of the ring ringing cutnoii relay 33 connects the tip conductor ing keys 153, 54, ‘55 or 53 that may be in the ring of the calling plug P2 to ground potential through ing position will be automatically released and Contact 43 of ringing call key, contact 4l of relay restored to normal. The automatic ringing start 43 and contact 35 of relay 33, and also connects 70 for frequency 5`is established through contact 45 negative-battery superimposed ringing current of the lever ringing call key since contact 45 of from the lower front contact of ringing key 55, the lever ringing call key is in multiple with con-v lower back contact of ringing key'5íâ, lower, or tact 41 of the button ringing key assembly, thus line»,A winding of relay 33, contact 32 of relay 33, operating and locking up relay 33 in» a similar contact 44A of theïringing‘call key tothe ’ring cone` 75 2,410,866 manner to that described for frequency 2. The ringing circuit for frequency 5 may be traced from the lower back contacts of ringing keys 53, 54, 55 and 56, through the lower winding of re lay 33, contact 32 of relay 33, ring conductor of calling plug P2, out on the line and returning over the tip conductor through contact 35 of re lay 33 to ground potential. When the called line is of the local battery type, the operator signals the desired telephone man ually by means of the lever'ringing call key as sociated with the calling plug P2. Uninterrupt ed generator of frequency 5 is supplied to the ring side of calling plug P2 through contact 43 of ringing call key and then out on the line and returning over the tip conductor to ground at Contact 4l of ringing call key. ' , ring side. Operating the cut-off answer key dis-V connects the operator telephone set at contacts |08 and || 2, and places a bridge | I0 across the repeating coil via conductors 60 and 6|, thus enabling the operator to converse with the called party via conductors 64 and 65 without overhear ing by the calling party. In a similar manner, the operator may converse privately with the call ing party by operating the cut-off call key. Fig. 2 may incorporate any of the Well-known common position key operations such as dial keys, refund and collect paystation keys shown in Crocker Patent 1,771,842 and any other key functions known to the telephone art. Disconnect supervision is obtained on a com pleted connection where both the calling and called lines are common battery, when the calling _and called parties restore their handsets to the .After the operator has completed a connection between the calling and called party, she may operate the talk key of the cord circuit to split 20. respective cradles, and the transmission battery feed relays I6 and 23 correspondingly restore to the cord circuit into two sections and switch au normal. Responsive to the releasing of relay I6, tomatically both sections of the cord circuit to the circuit of the answering cord supervisory lamp the common position circuit shown in Fig. 2, for is closed from ground potential at the upper make the purpose of monitoring the established con contact of relay |'|, back contact of relay I6, an ' nection, talking to either party without overhear 25. swering supervisory lamp to negative battery; and ing by the other party, refunding and collecting responsive to the releasing of relay 23, the circuit paystation deposits, or performing any other of the calling cord supervisory lamp is closed from functions that may be associated with the com ground potential at contact 22 of relay I9, con mon position circuit. As previously explained, 3'! of relay 33, upper back contact of relay the operation of splitting relay 29 switches the 301 tact 23, calling supervisory lamp to negative battery. tip and ring conductors of the answering` plug Disconnect supervision when the calling line is PI to the common Iposition circuit via conductors of the local battery type is obtained by the calling 60 and 6|. The tip and ring conductors of the party turning the hand generator of his tele calling plug P2 are switched to the common po sition circuit via contact 46 of the ringing call key, contact 4| of relay 40, contact 36>of relay 33, the upper make-before-break contact of relay 29 and conductor 64 for the tip side; and contact 44 of the ringing call key, contact 3| of relay phone. As previously explained, sleeve relay |`| does not operate when the answering plug Pl is 4inserted into jack J | because of the high re sistance value of relay |0. The lower Winding of relay |2, therefore, remains connected to the repeating coil at contact |8. current 33, the lower make-before-break Contact of re 40 from the hand generator causesRinging relay |2 to op lay 29 and conductor 65 for the ring side. erate and close Contact |5 and thereby complete 'I‘he operation of relay 29 by the talk key also the holding circuit of relay I2 from ground po connects .the sleeve of the calling plug P2 to the tential at contact 30 of relay 29, contact |5 of common position circuit via the center make-be relay |2, upper winding of relay I?. to negative fore-break contact of relay 29 and conductor 63; 45 battery. Responsive to the locking of relay |2, and the sleeve relays I9 and 40 in multiple via the circuit of the answering cord supervisory lamp the center front contact of relay 29 and conduc is closed from ground potential at contact I4 tor 62. The purpose of disconnecting the sleeve relay |2, answering supervisory lamp to negative of the calling plug P2 from the associated sleeve battery. The resistance coil || wired in multiple relays I9 and 40 and extending both units to the 50 with the upper winding of relay | 2 provides spark common position circuit is to enable the operator protection for contact |5. The resistance coil |3 to insert automatically a dial in the sleeve con connected in multiple with the lower winding of ductor of the calling plug P2 when the call is to relay |2 when relay |2 is locked up, provides a be extended to an automatic switchboard. The lay-pass for subsequent ringing current to pro circuit details of the dial connections have been 55 tect relay I2 from accidental ring down should omitted from Fig. 2 as it is understood that such suincient ringing current pass through its lower details are not essential to an understanding of winding to neutralize momentarily the holding the invention. current in the upper winding. Fig. 2 is equipped with cut-oil keys for cutting off either the answering or calling plugs and con 60, Disconnect supervision when the called line is of the local battery type is obtained by the called necting them to the operator’s telephone equip party turning the hand generator of his telephone. ment shown to the left on Fig. 2. A commonV Sleeve relay I9 does not operate when the calling monitoring key is also shown in Fig. 2 which, plug P2 is inserted into jack J2 because ofthe when operated, causes the associated switching relay |04 to connect the operator's receiver to a 65 high resistance value of relay 48. The lower wind ing of relay 26, therefore, remains connected to monitoring coil for the purpose of monitoring an the repeating coil at contact 20. Ringing cur established connection without materially reduc» rent from the hand generator causes relay 26 to ing the transmission eiûciency orin any wayin operate and close contact 28 and thereby com terfering with the‘connection. The monitoring' circuit may be traced from operator receiver, 70 plete the holding circuit of relay 26 from ground potential at contact 30 of relay 29, contact 28 of upper winding of monitor coil, contact |06 of relay 26, upper winding of relay 26 to negativerelay |04, contact | |2 of cut-oiî answer key and battery. Responsive to the locking of relay 26, the conductor 60 for the tip side, and from operator circuit of the calling cord supervisory lamp is receiver, contact |03 of relay |04, contact |08 of cut-off answer key and conductor 6| for the 75 closed from ground potential at the upper front contact of relay 26, upper back contact of relay 2,410,866> 9 .. 10 operator-controlled means «for establishing a con 23, calling supervisory lam-p to negative battery. nection to said party line, a` plurality of signal The resistance coil I2"! wired in multiple with the ling current sources, means for vselect-nig the upper winding of 'relay 26 provides spark protec proper source to signal a party on said line, a tion for contact 2li. The resistance coil 25 con relay having two windings, operator-controlled nected in multiple with the lower winding ci relay 26 when -relay 26 is locked up, provides a means for operating said relay through one wind ing thereof to close a signalling circuit including said selected source, the other winding of said relay »and the called line, and. means controlled by by-pass for subsequent ringing current to protect relay 26 from accidental vring down should Suni cientringing current pass through its lower wind the called party’s response .for .releasing said Írelay .ing to neutralize momentarily the holding current 10 to disconnect said sourcefrom the called line. in the upper winding. The vcondenser in series with the lower winding of relay 2li is provided for .4. In a telephone system, subscribers’ lines, op extending `a connec tion to one of said lines, a signalling current source including a direct current qsuperimposed on an alternating current, a relay having two ` crater-controlled .means for the purpose of preventing supervisory signal in terference between a common battery line on one cord circuit and a local battery line on an other cord vcircuit should the operator use the windings, operator-controlled means for energiz talk keys of both cord circuits for “over-lap” ing said relay through one winding thereo'f- .to close a signalling circuit yincluding said Isourcaft'he service. A common group of iive push button ringing other winding >of said relay 'and the ‘called line, keys shown at the lower left on Fig. l is multipled 20 the alternating current component of said source to the lever ringing keys associated with the an supplying the power .ior'signalling the .called'line swering plugs of the cord circuits to enable the and means including the direct current com operator. to rering parties on the answering plug ponent of said source »and responsive lto the called PI. The rering is done on a manual basis only, subscriber answering for releasing said .relay "to with the operator applying the ringing current disconnect said source. 5. In a telephone system, subscribers" lines, by means of the lever ringing key associated with the answering plug Pl. No wiring is required on means for extending a connection to one o'f said lines, a source of signalling current, a relay in cluding a winding, a key for causing said relay the 4frequency 5 ringing key, as frequency 5 is wired through the back contacts of the ringing keys associated with frequencies I, 2, 3 and 4 to 30 to operate and complete a signalling circuit in cluding said source, said winding and Ythe called the ringing common contact on the R side of the lever ringing key. Frequency 5 ringing button is line, and means for releasing saidrelay respon sive to the called subscriber answering, said sig depressed when frequency 5 `ringing current is required, in Order to release and restore any of nalling circuit being instantly disconnected when the ringing keys associated with frequencies l, said relay releases. 2, 3 or 4 that may be in the ringing position. The lever ringing keys associated with both the’ answering and calling -plugs, and also splitting relay 33, are ñtted with an extra iront contact for starting the .ringing machine whenever Ysuch , , 6. In a telephone system, a called line, means for establishing a connection to said line, a sig nalling current source, a double-wound relay, a key vfor completing a circuit through one winding 40 of said relay for causing >said relay -to operate and lock through >said Winding yto close a signal well-known ringing varrangements are provided. It should be understood that while `the forego ling circuit for said line, said signalling Acircuit including said source, the second winding oisaid ’ ing description and .associated drawings disclose the invention as specifically used on connecting relay and the called line, and means ycontrolled circuits ofthe manual vswitchboard cord type, ‘the lby the called party’s response vfor causing .the invention is not limited to such connecting cir cuits but may be applied to any type of connecting circuit in which automatic ringing is employed. Having described the invention and what is considered new and desired to 'be protected by Letters Patent is set forth in the following claims: What is claimed ist release of said relay `to disconnect said .source l. In a telephone system, a calling and a called line, operator-controlled means for establishing a connection between said lines, a source vof sic nalling current, a relay, operator-controlled means for operating said relay to close `a signal ling circuit including said source and the called line, and means eiiective upon the response of the called party for operating said relay in series with said line to disconnect said signalling circuit from said line. y 2. In a telephone system, a calling and a called line, operator-controlled means i or :est a'blisloingV from said line. ~ '7. In a telephone system, `a 'called party 1ine, means for establishing a connection to said party line, a plurality of signalling current sources, a plurality of keys for selecting the proper source , to signal the called substation on said line, :a relay having a pair of windings, a circuit controlled by any one of said `plurality of keys for energizing .and locking said relay through one winding there of to close a signalling circuit including said se lected source, the other winding of said relayçand the called line, said relay releasing responsive -to ` 60 the called substation answeringr »to disconnect ~ said source from said line. , 8. In a telephone system, a called party `line, mean-s for establishing a connection to said line, a plurality of signalling current sources, ’a plu rality of resistances, a relay, means for selecting> the proper source to signal the called substa tion, for selecting a portion of said plurality of resistances dependent vupon the particular source a connection between said lines, ‘a source of vsig nalling current, ‘a relay having a pair of windings, operator-controlled means Tor completing the cir cuit of one winding ci’ said relay for causing said selected, and 'for operating said relay in series relay to operate and close a signalling circuit `in with said selected portion of said resistancesto cluding said source, the other winding of said 70 close a signalling circuit including said selected relay and the called line, and means effective upon source and the called line, and means controlled the response of the called party for releasing said by the called substation’s response for operating relay to disconnect said signalling circuit from said line. 3. In a telephone system, a called. party line, said relay to disconnect said signalling circuit. V9. rIn a Y«telephone system, a called party line, 11 2,410,866 means for establishing a connection to said line, a plurality> of signalling current sources, a plu rality of resistances, a relay, means for selecting one of said sources to signal a party on said line, for selecting a portion of said plurality of re sistances dependent upon the particular source selected, and for closing a circuit for said relay in series with said selected portion of said resist ances, a signalling circuit closed by the opera 12. with said selected portion of said resistances, and a signalling circuit closed by the operation of said relay and including said selected source, said relay and the called line. 14. In a telephone system, a called party line, operator-controlled means for establishing a con nection to said line, a plurality of signalling cur rent sources, a plurality of resistors, a plurality of keys for selecting one of said sources to signal tion of said relay, said signalling circuit including 10 a party on said line, and for selecting one or said selected source, said relay and the called line, and means eiîective upon the response of the called substation for releasing said relay to dis more of said resistors to form a resistance of certain value a relay, a circuit controlled by any one of said plurality of keys for operating said relay in series with said selected resistor or re 10. In a telephone system, a party line, means 15 sistors, a signalling circuit closed by the opera for extending a connection to said line, a plural tion> of said relay and including said selected ity of signalling current sources, .a plurality of source and said line, and means controlled by resistances, a differentially-wound relay, means the called substation’s response for operating said i'or selecting the proper source to signal the called relay to disconnect said source. substation, for selecting a portion of said plu l5. In a telephone system, a party line, means rality of resistances dependent upon the particu for extending a connection to said line, a plu lar source selected, and for energizing said relay rality of signalling current sources, a plurality through one winding ithereof in series with the of resistors, a plurality of keys for selecting dif said selected portion of said resistances, a sig nalling circuit closed by the operation of said re 25 ferent sources to signal different stations on said line, and for selecting one or more of said lay, said signalling circuit including said selected resistors dependent upon the particular source source, the other Winding of said relay and the selected, a relay, a circuit controlled by any one called line, said relay releasing in response to the of said keys, a signalling circuit closed when said called station answering to disconnect said signal relay is energized in series with said selected re ling circuit. 30 sistor or resistors over said operating circuit re 11. In a telephone system, a party line, means sponsive to the operation of one of said keys, said for extending a connection to said line, a plu signalling circuit including said selected source, rality of alternating `current signalling sources said relay and the called line, and means effective including a direct current superimposed on each upon the called station’s response for releasing of said plurality of sources, a plurality of re ' said relay to open said signalling circuit. sistors, a relay, means for selecting one of said 16. In a telephone system, a party line, means sources to signal a party on said line, for select for extending a connection to said line, a plu ing one or more of said resistors to form a re rality of signalling current sources, a plurality of sistance of, certain value dependent upon the particular sour-ce selected, and for connecting 40 resistors, a plurality of keys for selecting dilTer ent sources to signal diiîerent stations on said said relay in series with said selected resistor or line, and for selecting portions of said resistors resistors, a signalling circuit including said se dependent upon the particular source selected, lected source and the called line and closed by the a double-Wound relay, a circuit controlled by’ operation of said relay, the alternating current any one of said keys for energizing and locking component of said source supplying the power for said relay through one winding thereof in series signalling the called substation, and means in with said selected portion of said resistors, a sig cluding the direct current component of said nalling circuit closed by the operation of said source and controlled by the called station’s re relay and including said selected source, the sponse for operating said relay to open said sig other Winding of said relay and the called line, nalling source. ` and means controlled by the called station an 12. In a telephone system, a party line, opera swering for releasing said relay to disconnect said tor-controlled means for extending a connection source from said line. to said line, a plurality of signalling current 17. In a telephone system, a called party line, sources, a plurality -of resistances, means for se means for establishing a connection to said line, lecting the proper source to signal a party on a plurality of alternating current signalling said line, and for selecting a portion of said plu sources including a direct current superimposed rality of resistances dependent upon the particu on each of said plurality of sources, a plurality lar source selected, a relay, operator-controlled of resistors, a plurality of keys for selectingr dif means for closing a circuit for said' relay in se ferent sources to signal diiîerent stations on said ries with said selected portion of said resistances, 60 line, and for selecting portions of said resistors a signalling circuit closed by the operation of said to form resistances of certain values dependent relay, said signalling circuit including said se upon the different sources selected, a relay, a cir lected source and said line, and Vmeans effective cuit controlled by any one of said plurality of upon the response of the called party for releas keys for causing said relay to be energized in ing said relay to disconnect said source from said series With a particular selected resistance value, line. -» and a signalling circuit closed by the operation 13. In a -telephone system, a called party line, of said relay and including said selected source operator-controlled means for establishing a con and the called line, said signalling circuit being nection to vsaid party line, a plurality of signal disconnected when said relay releases responsive ling current sources, a plurality of resistances, a 70 to the called station answering. relay, operator-controlled means for selecting the 18. In a telephone system, a called party line, proper source to signal the called substation, for means for establishing a connection to said line. selecting a portion of said plurality of resistances a plurality of signalling current sources, a plu dependent'upon the particular source selected, rality of resistances, a differentially-wound relay, and for closing a circuit for said relay in series connect said source. 75 a balancing circuit including one winding of said 2,410,866 13 relay, means for connecting diiîerent ones ofsaid sources to said line through the other wind ing of said relay to signal diiîerent stations on said line, and for connecting diiîerent values of resistance in series with said balancing circuit to compensate for different sources connected to the other winding of said relay. 19. In a telephone system, a party line, means for extending a connection to said party line, a 10 plurality of signalling current sources, a plural ity of resistances, a differentially-Wound relay, a balancing circuit including one winding of said 14 relay, means for connecting any of said sources to said line through the other Winding of said relay to signal a party on said line, and for con necting the proper value of resistance in series with said balancing circuit for providing the proper power in the balancing circuit winding of said relay to neutralize the power developed in the other winding of said relay when the called `party answers, said neutralization causing the release of said relay to disconnect said source. KARL L. BURGENER.