US2056265A - Telephone system - Google Patents

Description

c. E. GERMANTON Oct. 6, 1936.

TELEPHONE SYSTEM 10 Sheets-Sheet 1 Filed Aug. 15, 1935 6 A TTOR/VEV Oct. 6, 1936. c. E. GERMANTON TELEPHONE SYSTEM I Filed Aug. 15, 1955 10 Sheets-Sheet z" 'n v a J n? )i I g Y' w l' I IHI I .w o g 8 f g :Z a @H'H '2 sk I] I Q 1 1 ll J w T a -"1 l t g g \N a lNl/ENTOR By CE GERMAN TON aam ATTORNEY Oct. 6, 1936. c. E. GERMANTON TELEPHONE SYSTEM '10 Sheets-Sheet 4 .PoN

Filed Aug. 15, 1935 g lNl/ENTOR v CE. GERMANTON By M NMN hvm WNW mvN A T TOR/VEV Oct. 6, 1936. c. E. GERMANTON TELEPHONE SYSTEM Filed Aug. 15, 1955 10 Sheets-Sheet 5 \R MW NR QQQ mNm R N lNl/ENTOR IF I CEGERMANTON l I I I I I I I I f I I I I F I I I I I I I I I I I I I WWW Nvm RM I I I I I I I r I I I x v.- v v I l l l l I I I I I I I I I I I I l I I l I I I l l I l r I r r r r rr r r r r r r r I r r IIII A T TORNE I TAN-H TAN T Oct 6, 1936.

c. E. GERMANTON TELEPEIQNE SYSTEM Filed Aug. 13 1955 &

' 1O Sheets-Sheet 6 lNl EN y CEGERMAN TON ATTORNEY Oct. 6, 1936.

c. E. GERMANTON TELEPHONE SYSTEM Filed Aug. 15, 1955 10 Sheets-Sheet 7 llj lNl ENTOR CE. GERMANTON ATTODA/FV Oct. 6, 1936. c. E. GERMANTON TELEPHONE SYSTEM Filed Aug. -15, 1955 10 Sheets-Sheet 8 Wm vvm WWW INVENTOR C. 5. GERMAN 7'0/V By 6P6.

AT TOR/VEV Oct. 6, 1936. -c GERMANTON L 2,056,265

TELEPHONE SYSTEM Filed Aug. 13, 1955 10 Sheets-Sheet 9 lNl/ENTOR y CEGERMANTON A T TORNE Y Oct. 6, 1936.

C. E. GERMANTON TELEPHONE SYSTEM Filed Aug. 15, 1935 10 Sheet eet 10 lNl ENTOR By C. E. GERMANTON A T TORNE) Patented Oct. 6, 1936 UNITED STATES PATENT OFFIQE TELEPHONE SYSTEM Application August 13, 1935, Serial No. 35,917 17 Claims. (01. 179-18) This invention relates to telephone systems and more particularly to senders in which series of impulses indicative of the designations of subscribers lines are registered for the purpose of controlling the extension of connections to such lines.

In large multi-office exchange areas register senders are employed in the several offices for controlling the setting of automatic switches for extending connectionsto other offices and to subscribers lines terminating in the originating office or in the other oiiices. Such senders are equipped either with step-bystep register switches responsive to dialed impulses or with 1 5 registers of the relay type for recording the designations of desired connections and with mechanism responsive in accordance with the registered information for controlling the establishment of connections. In senders of the type 20 employing registers of the relay type, each register for registering a digit of a designation comprises four or more relays and since it is usually necessary to register three digits for identifying the ofiice in which a desired line terminates, four 25 digits .to. identify the number of the line and for party lines an identifying party letter, eight registers are necessary involving at least thirtytwo relays. Further, in systems employing senders of the decoder type as in the well-known panel system, each sender must have additional registers to record information for setting selector switches to extend a connection to another ofiice of the exchange area in accordance with the translation made by the decoder of the office identifying digits registered in the sender. In the panel system four such registers are employed in the decoder sender each having at least four relays or a total of sixteen relays. Thus, a sender of this type employs at least forty-eight reg- 40 ister relays. Typical senders of this character are disclosed in Patent No. 1,862,549 granted June 14, 1932 to R. Raymond ct al showing a local office sender and in Patent No. 1,840,132 granted January 5, 1932 to T. H. Roberts, show- 45 ing, a tandem oflice sender.

The object of the present. invention is to reduce the initial cost, maintenance, current drain and required floor space of register senders by employing condensers as registers, replacing the 5; register relays heretofore employed, whereby a considerable economy is realized. v

In accordance with the present invention this object isattained in a tandem. decoder sender of the type disclosed in the patent to Roberts, here- 55 inbefore referred to, in the following manner: In

the tandem sender the designations identifying a desired line are received therein as series of impulses in accordance with the well-known call indicator code characters. These impulses are received by three relays, one of which responds to 5 impulses of either light or heavy positive potential, a second of which responds to impulses of either light or heavy negative potential and a third of which is marginal and responds only to heavy impulses of either positive or negative potential.. Associated with these relays are two other relays of the well-known W and Z type which selectively place the condensers of groups of condensers functioning as receiving registers, in a charged or uncharged condition in accordance with the codes of received impulses. Each register for registering the code impulses comprises four condensers, the first of which will be charged and remain charged if the first impulse of a code is blank, but will be discharged if the first impulse is positive, the second of which will be charged and remain charged if the second impulse is light negative, but will be discharged if the second impulse is heavy negative, the third of which will be charged and remain charged if the third impulse is blank, but will be discharged if the third impulse is positive and the fourth of which will be charged and remain charged if the fourth impulse is light negative, but will be discharged if the fourth impulse is heavy negative. Eight condenser registers are provided for regi'steringin the order of their reception the series oficod'e impulses designating the three office code digits, the stations letter and the thousands, hundreds, tens and units niunerical' digits of the line designations.

In order that the condenser registers may be associated successively and in the proper order the impulse receiving relays, a so-called walking or sequence circuit is provided which 40 comprises a second pair of W and Z relays and a train of relays, one individual to each register. This sequence circuit is controlled by the first pair of W and Z relays.

As soon as the oflice code digits have become 5 registered a decoder is associated with the sender in, the usualv manner for the purpose of translating the office code digits into the proper routing information for routing the call to an office from which the desired line may be reached. To accomplish this, it is necessary to transfer the office code registrations to registers in the decoder, make: the necessary translation. in. the decoder and then retransmit the translated routing information. to registers in the sender which may then be effective to direct the sender in its control of selector switches to trunk the call to another ofiice of the exchange area. In accordance with the present invention these routing or transmitting registers of the sender are also of the condenser type, four such registers being supplied for controlling district brush and group and oflice brush and group selections.

Thus, upon the association of a decoder with a sender receiving paths must be established from the condensers comprising the three office code registers to the receiving registers of the decoder and transmitting paths must be established from the decoder to the transmitting registers of the sender and a check made to determine if these paths are all in efiicient working or operative condition. A check is first made to determine if the receiving paths are all properly established and coincidentally the ofiice code registrations are transferred over these paths to the receiving registers of the decoder. For the purpose of mak ing the check of each path and the transfer thereover of the registration condition of the particular register condenser of the sender associated therewith, a group of relays is provided in the decoder for each receiving path.

Each group of relays comprises two oppositely polarized relays connected to the associated receiving path through a potentiometer, one of which will operate if the register condenser in which the sender end of the path terminates, is in a charged condition and the other of which will operate if the condenser is in an uncharged condition. Thus, one or the other of these relays will operate if the path is in an operative condition and will thus afford a check on the condition of the path. Associated with these relays are two other relays whose operated or unoperated condition is controlled by the first relays and which serve as a register to register the registering condition of the condenser. These four relays function together to control a fifth relay which serves as a check relay to indicate the operative condition of the path, being operated only if the path is operative and to check for crosses with battery or ground.

Three main groups of these groups of relays are provided corresponding to the three office code registers of the sender, one main group of four groups serving to check the four receiving paths extending from the four condensers of the first oflice code register and to register the first code digit in the decoder, a second main group of four groups serving to check the four receiving paths extending from the four condensers of the second oifice code register and to register the second code digit in the decoder, and a third main group of four groups serving to check the four receiving paths extending from the four condensers of the third oifice code register and to register the third code digit in the decoder.

If all of the check relays of these groups are operated indicating that all receiving paths are operative and that the oifice code registrations have been registered in the decoder, the decoder then proceeds in the usual manner to translate the registrations by operating a route relay and by setting transmitting register relays of the decoder. The transmitting paths extending from the decoder to the condensers of the selection registers of the sender are now checked and the information registered on the selection registers of the decoder is transmitted to the selection registers of the sender. Each transmitting path was extended through one of the condensers of the selection registers in the sender, through the winding of a check relay and to the mid-point of a potentiometer upon the association of the decoder with a sender so that each condenser of the selection registers was thus charged to an intermediate potential if the transmitting path was intact. Therefore, when the check of the transmitting path is started, the potential on all transmitting paths at the decoder is changed from the intermediate potential to either ground or increased battery potential in accordance with the operated or unoperated condition of the selection register relays of the decoder and if a transmitting path is in an operative condition the check relay therein should operate either by the discharge therethrough of the partially charged condenser connected therewith at the sender or by the further charging of such condenser therethrough. Thus, at the end of the checking operation the condensers of the selection registers of the sender will have been placed in a charged or discharged condition in accordance with the setting of the selection registers of the decoder if all transmitting paths are in an operative condition and all check relays will have operated to close a circuit for disconnecting the decoder from the sender. The sender now has registered therein all of the information required for completing the call.

The sender may now proceed to establish the desired connection. If the connection may be completed either in the tandem ofiice or in another local ofiice by the setting of selector switches, the sender proceeds to cause the setting of a district selector or both the district selector and an ofiice selector in accordance With the setting of its selection registers and the setting of an incoming selector and a final selector in accordance with the setting of the thousands, hundreds, tens and units receiving registers. The usual revertive impulsing control circuit including a stepping relay and counting relays is employed for this purpose, but as the sender registers comprise condensers rather than relays, the registrations are successively transferred in the proper order to a secondary register comprising a group of four registering relays which in the usual manner control the counting relays during each selection control.

The relays of the secondary register are associated with a group of four charge detecting relays which are successively associated with a group of condenser registers by the previously mentioned sequence circuit. Upon the association of the detecting relays with each group of condensers they are selectively operated by the discharge of the charged condensers of the group therethrough and in turn selectively determine the operated or unoperated condition of the relays of the secondary register whereby the secondary register reregisters the digits or information previously registered on the condenser register at the time associated therewith. Thus, during the establishment of a full mechanical connection the secondary register assumes successively the district brush and group and ofiice tandem oflice, it is necessary first to control the til-O lowing code will be transmitted from the sender in the originating office:

Registration of call designation The first code impulse which, as shown above, is a heavy negative causes the operation of relays 2I2 and 2I4. Relay H2 in operating connects ground from conductor I09 over its front contact, inner lower normal contacts and winding of relay 209, resistance 2l1 to battery. Relay 209 operates and looks over its inner lower alternate contacts to ground on conductor I09. With relay 209 operated a charging circuit for condenser 220 is established from battery through resistance 2I0, lower back contact of relay 2 I 0, inner upper front contact of relay 209, resistance 224, upper back contact of relay 208, conductor 225, next-toinner upper contact of relay 200 to ground through condenser 220. Relay 209 also closes a circuit from battery through resistance 220, winding of relay 2I0, inner lower alternate contacts of relay 209 to ground on conductor I09 to prepare relay 2! for operation. Relay H is prevented from operating at this time by ground connected over the contacts of relay 2 I2, the inner lower back contact of relay 2 I 0 to resistance 226 in shunt of the winding of relay 2I0.

Relay 2M upon operating closes a circuit from ground on conductor I09 over its contact, the upper back contact of relay 2I0 through resistance 222, thence .as traced to ground through the previously charged condenser 2I9 causing the condenser to immediately discharge. When the impulse terminates relays M2 and 2M release, relay 2I2 removing the shunt from around the Winding of relay 2I0 which now operates. With relay 2I0 operated a circuit is closed from battery through resistance 221, the winding .and inner lower normal contacts of relay 201 to ground at the inner upper contact of relay 2"). Relay 2 01 operates and looks over its inner lower alternate contacts to ground on conductor 228 supplied from conductor I09 over the front contact of relay 2I I, and prepares an operating circuit for relay 208 extending from battery through resistance 220, win-ding of relay 208, inner lower alternate contacts of relay 201 to ground on conductor 228. Relay 208, however, is prevented from operating at this time by ground connected over the inner upper front contact of relay 2E0 and the inner lower back contact of relay 208 to resistance 229 in shunt of the winding of relay 208. Relay 201 upon operating closes an operating circuit for transfer relay 20! which may be traced from battery through the winding of relay 20I, lower contact of transfer relay 200, conductor 232, lower front contact of relay 201 to groundon conductor 228. Relay 2I0 upon operating also closes a charging circuit for condenser 22I extending from battery through resistance 2I6, lower front contact of relay 2I0, lower front contact of relay 209, resistance 230, inner upper backcontact of relay 208, conductor 23I, inner upper contact of relay 200 to ground through condenser 22I.

The next impulse received is light negative and therefore relay 2 I2 operates alone and closes a circuit from ground on conductor I09 over its contact, inner lower front contact of relay 2I0 to resistance 2 in shunt of the winding of relay 209 which now releases. The inner lower contact of relay 209 being of the continuity type, relay 2 I0 does not release upon the release of relay 209, but is held operated over the inner lower normal contacts of relay 209 and the contacts of relay 2I2 to ground on conductor I00 until the impulse terminates. With relay 209 released and relays H0, 201 and 20I operated a charging circuit" is established for condenser 234 extending from battery through resistance 2"), lower front contact of relay 2I0, lower back contact of relay 209, resistance 238, upper front contact of relay 201, conductor 239, upper contact of transfer relay 20I to ground through condenser 234.

When relay 2I0 releases upon the termination of the impulse, relay 208 operates and at its lower normal contacts opens the locking circuit of transfer relay 200 which now releases. At its lower alternate contacts relay 2) establishes a locking circuit for transfer relay 20I extending from battery through the winding and inner lower contact of relay 20I, conductor 233, the alternate contacts of relay 208 to ground on conductor 228. Since the lower contacts of relay 208 are of the continuity type, the locking circuit of relay MI is closed prior to the opening of the locking circuit of relay 200 and the consequent opening of the operating circuit of relay 20!. Relay 2"] upon releasing also establishes a charging circuit for condenser 235 extending from battery through resistance 2 I0, lower back contact of relay 2 I0, inner upper back contact of relay 209, resistance 222, inner upper front contact of relay 201, con ductor 240, neXt-to-upper contact of transfer relay 20I through condenser 235 to ground.

Prior to and during the first series of code impulses condensers 2I8 to 22I, inclusive, 230 and. 235 were successively charged and condenser 2I9 was discharged to register the first code letter C.

During the reception of the first impulse of the second code letter H, relay 2I2 is operated alone and as described, causes the operation of relay 209. Relay 209 upon operating establishes a charging circuit for condenser 230 extending from battery through resistance 2B6, lower back contact of relay 2 I0, inner upper front contact of relay 209 through resistance 224, upper front contact of relay 208, conductor 2 neXt-to-inner contact of relay 2!) I to ground through condenser 236. At the end. of the impulse relay 2I0 is also operated closing a charging circuit for condenser 231 extending from battery through resistance 2I6, lower front contacts of relays 2I0 and 209, resistance 230, inner upper front contact of relay 208, conductor 242, inner'upper contact of relay 20I to ground through condenser 231. Relay 2 I0 also connects ground over its inner upper contact,

'theinner lower front contact of relay 208 to resistance 221 in shunt of the winding of relay 201 which now releases. Since the inner lower contacts of relay 201 are of the continuity type, relay 208 does not release at this time, but is held operated over the inner lower normal contacts of relay 201 to ground at the inner upper contact of relay 2I0. Relay 201 upon releasing establishes an operating circuit for transfer relay 202 which may be traced from battery through the winding of setting of either a district selector or both a district selector and an oifice selector to trunk the call to such office and to then transmit by codes of call indicator impulses information necessary to enable the operator at such ofiice to complete or further extend the connection. To extend the connection to the distant manual office .the sender functions as previously described to revertively control the Setting of district and office selectors in accordance with the setting of the selection registers of the sender, For the transmission of call indicator impulses to the selected manual oifice the usual standard call indicator impulse generator is employed, the codes of impulses transmitted thereby being determined by the charge detecting relays which are selectively operated through their association .with successive receiving registers. The same sequence circuit is employed for associating the detecting relays with successive registers.

For example, if the connection is made to a manual tandem office it is necessary to retransby codes of impulses the entire oiiice code, station and numerical designations of the wanted line and thus the three oifice code, stations, thousands, hundreds, tens and units registers are successively associated with the detecting relays in the order named. If, however, the connection is to be made to a manual terminating office it is not necessary to retransmit the oflice code designation and therefore, following the selection of the oiiice the stations, thousands, hundreds, tens and units registrations are retransinitted.

Although for the purposes of illustration the novel features of the invention have been disclosed as applied to the decoder sender of a panel type system, it will be obvious that the invention is equally applicable to systems of the stepby-step type in which directive impulses are transmitted from a sender for controlling stepby-step switches, or to systems of the cross-bar type, since in its broad aspect, the invention relates primarily to registration of incoming impulses on registers comprising condensers and to the utilization of the charged or uncharged condition of the condensers of the registers to control selective operations. It will also be evident that while the selective placing of the condensers of a register in a charged or uncharged condition has, for the purposes of illustration, been disclosed as under the control of call indicator impulse responsive means, any other wellknown form of impulse responsivemeans could equally well be employed.

For a clearer understanding of the invention reference may be had to the following detailed description taken in connection with the accompanying drawings in which:

Figs. 1 to 4, inclusive, show as much of a tandem sender as is considered necessary to an understanding of the invention; Fig. 1 showing the counting relays, stepping relay and out-pulsing control relays; Figs. 2 and 3 showing the impulse receiving and registering equipment and Fig. 4 showing the call indicator impulser;

Figs. .5 to 10, inclusive, show as much of a decoder as is considered necessary to an understanding of the invention Fig. 5 showing schematically a portion of the decoder connector and one of the code registers; Fig. 6 showing the remaining two code registers; Fig. '7 showing the translation equipment and one of the route reys; Fig. 8 sh wi g e Qflic r p se c on through the winding ,of relay 2H.

register; Fig. 9 showing the, district group selection register and Fig. 10 showing the district and ofiice brush selection registers; and

Fig. 11 is a diagram showing the manner in which the figures should be arranged to completely disclose the invention.

It is believed that the invention will be best understood through the detailed description of the establishment of typical connections. Since, however, the invention is chiefly concerned with the sender and decoder the trunking facilities over which a call is directed to the tandem sendor and over which the sender controls the further extension of connections, are not disclosed herein. For such trunking facilities reference may be had to Patent No. 1,840,132 hereinbefore referred to. It will therefore be assumed that a call is incoming to the tandem oflice and that a link circuit, not shown, tests for an idle sender.

An idle sender is characterized by battery through a resistance, such as resistance I09, con.- nected to test conductor I8 I. Assuming that the sender shown is the first idle sender, when the sender-finder of the link tests conductor IUI, the

sender-finder is arrested in its hunting movement and the sequence switch of the link is advanced in the usual manner whereupon a circuit is'established over conductor I02, back contact of relay I03, windings of relay Hid to ground. Relay I04 operates, in turn operating relays I85 and IE6. Relay I35 establishes an operating circuit for transfer relay 260 which extends from battery through the winding of relay 2%, over conductor I91, the back contact of relay I08 to ground at the upper front contact of relay I05. Relay 20!) operates and extends its operating ground over its inner lower front contact, conductor 249, the lower normal contact of relay 298 to battery Relay 2II operates establishing a locking circuit for itself and for relay 200 over its front contact, conductor I09 to ground at the lower front contact of relay I05. Prior to the operation of relay 2, condenser 2I8, associated with relay 2%, is charged in a circuit from battery through resistance 2I6, lower back contact of relay 2I0, back contact of relay 2 through condenser 258 to ground. As soon .asrelay 20B operates a charging circuit for condenser 2 I 9 is established from battery through resistance ZIB, lower back contact of relay 2I0, inner upper back contact of relay 2139, resistance 222, inner upper back contact of relay 201, conductor 223, next-to-upper contact of relay 200 to ground through condenser 2 I9.

Relay I06 upon operating causes the operation of relay IIil which looks and closes the operating circuit of relay I08. Relay I08 upon operating opens the initial operating circuit of relay 20!], connects ground to conductor I98 and disconnects battery through resistance Illll from conductor IOI thereby advancing the sequence switch of the link circuit. An in-pulsing circuit is now prepared in the usual manner from the sender in the originating office through the link circuit, over conductor I I I, back contact of relay 2 I 5, windings of relays 2I2, H3 and 2M in series, back contact of relay 2I5, conductor I I2, through the link circuit back to the sender of the originating oflice.

Relay 212 is polarized to respond to negative impulses, relay2 i 3, is polarized to respond to positive impulses and relay 2 I4 is marginal so that it responds to heavy impulses of either positive or negative polarity. Assuming that the desired subscriber s number is Chelsea 3-5678, the folrelay 202, the lower front contact of relay 20l, conductor 243, the lower back contact of relay 201 to ground on conductor 228.

The second impulse is positive causing the operation of relay 213 and the closure of a circuit from ground on conductor I09, contact of relay 213, upper front contact of relay 209 through resistance 224, upper front contact of relay 208, conductor 24!, thence as traced through condenser 236 to ground causing this condenser to discharge. The third impulse is light negative causing the operation of relay 212 alone. Relay 212 upon operating causes the release of relay 209 which establishes a charging circuit for condenser 244 extending from battery through resistance 2l6, lower front contact of relay 2|0, lower back contact of relay 209, resistance 230, upper back contact of relay 201, conductor 248, upper contact of transfer relay 202 through condenser 244 to ground. Upon the cessation. of this impulse relay 2l2 releases in turn releasing relay 2l0. With relay 2l0 released a charging circuit is established for condenser 245 extending from battery through resistance 218, lower back contact of relay 2|0, inner upper back contact of relay 209, resistance 222, inner upper back contact of relay 201, conductor 223, next-to-upper contact of relay 202 to ground through condenser 245.

Relay 2 upon releasing also opens the holding circuit of relay 208 which now releases and at its lower continuity contacts first closes a holding circuit for transfer relay 202. extending from battery through the winding and inner lower front contact of relay 202, conductor 249, lower normal contacts of relay 208 to ground on conductor 228 and then opens the previously traced holding cirsuit of transfer relay 20l which now releases.

During the pulsing for the second code letter H, condensers 236, 231, 244 and 245 have been successively charged and condenser 236 has become discharged.

The first impulse of the third code digit 3 is positive and relay 2|3 therefore operates and closes a circuit for discharging the previously charged condenser 244 which may be traced from ground on conductor I09, contact of relay 2l3, upper back contact of relay 209, through resistance 238, upper back contact of relay 201, conductor 248, upper contact of relay 202, through condenser 244 to ground. The second impulse which is heavy negative causes the operation of relays 2 l2 and 2 M as before described. Relay 214 closes a circuit for discharging the previously charged condenser 245 which may be traced from ground on conductor I09, contact of relay 214, upper back contact of relay 2 I0, through resistance 222, inner upper back contact of relay 201, conductor 223, the next-to-upper contact of relay 202 through condenser 245 to ground. Relay 2|2' upon operating causes the operation of relay 209, as previously described, and the establishment of a charging circuit for condenser 245 which maybe traced from battery through resistance 210, the lower back contact of relay 2 E0, the inner upper front contact of relay 209, resistance 224, the upper back contact of relay 200, conductor 225 the nextto-inner upper contact of relay 202, condenser 248 to ground.

'Upon the cessation of the second impulse relay 2 l2 releases and relay 210 operates in turn operating relay 201 as previously described. Relay 2H! upon operating also closes-a charging circuit for condenser 241 extending from battery through resistance 210, lower front contacts of relays 2l0 and 209, through resistance 230, inner upper back contact of relay 208, conductor 23!, inner upper contact of relay 202, condenser 241 to ground. Relay 201 upon operating opens the initial operating circuit of relay 202 and at its lower front contact closes the operating circuit of transfer relay 203 which may be traced from battery through the winding of relay 203, lower front contact of relay 202, conductor 232, lower front contact of relay 201 to ground on conductor 228.

The third impulse is light negative and therefore only relay 212 operates in turnreleasing relay 209. A charging circuit is now established for condenser 250 which may be traced from battery through resistance 216, lower front contact of relay 2 l0, lower back contact of relay 209, resistance 238, upper front contact of relay 201, conductor 230, upper contact of relay 203 to ground through condenser250. Upon the termination of this impulse relay 2| 0 releases followed by the operation of relay 208 as previously described. Relay 2I0 upon releasing closes the charging circuit for condenser 25I extending from battery through resistance 2H5, lower back contact of relay 210, inner upper back contact of relay 209, resistance 222, inner upper front contact of relay 201, conductor 240, next-to-upper contact of relay 203 to ground through condenser 25l. Relay 208 upon operating at its lower continuity contacts first closes the locking circuit of transfer relay 203 extending from battery through the winding and inner lower contact of relay 203, conductor 233, alternate contacts of relay 208 to ground on conductor 228 and then opens the locking circuit of transfer relay 202 which now releases. Thus, during the pulsing for the third code digit 3, condensers 246, 241, 250 and 25l have been successively charged and condensers 244 and 245 have been discharged.

Assuming that the called subscribers number includes no stations digit, the next digit received will consist of two light negative impulses which are equivalent to the digit zero. In response to the first impulse relay 242 operates in turn operating relay 209 which closes a charging circuit for condenser 252 which may be traced from battery through resistance 210, lower back contact of relay 2I0, inner upper front contact of relay 209, resistance 224, upper front contact of relay 208, conductor 24], next-to-inner upper contact of relay 203, through condenser 252 to ground. Upon the termination of this impulse, relay 2E0 operates followed by the release of relay 201. Relay 210 upon operating closes a charging circuit for condenser 253 which may be traced from battery through resistance 215, lower front contact of relay 2 I 0, lower front contact of relay 209, resistance 230, inner upper front contact of relay 208, conductor 242, inner upper contact of relay 203 through condenser 253 to ground. Relay 201 upon releasing opens the initial operating circuit of transfer relay 203 and at its lower back contact closes an operating circuit for transfer relay 204 extending from battery, winding of relay 204, lower contact of relay 203, conductor 243, lower back contact of relay 201 to ground on conductor 228.

In response to the second impulse, relay 2l2 again operates in turn releasing relay 209 which closes a charging path for condenser 254 extending from battery through resistance 2I6, lower front contact of relay 2E0, lower back contact of relay 200, resistance 238, upper back contact of relay 201, conductor 248, upper contact of relay 204 through condenser 254 to ground. Upon the termination of the second impulse, relay 2I0 releases in turn releasing relay 208. Relay 2I0 upon releasing establishes a charging circuit for condenser 255 extending from battery through resistance 2I6, lower back contact of relay 2I0, inner upper back contact of relay 209, resistance 222, inner upper back contact of relay 201, conductor 223, next-to-upper contact of relay 264, through condenser 255 to ground. Relay 208 upon releasing at its continuity contacts first closes the locking circuit of transfer relay 204 extending from battery through the winding and inner lower contact of relay 204, conductor 249, alternate contacts of relay 208 to ground on conductor 228 and then opens the locking circuit of transfer relay 203 which now releases. Thus, during the transmission of impulses for the stations digit zero, condensers 252, 253, 254 and 255 were successively charged and all condensers 250 and 253, inclusive, constituting the stations register were left charged.

The remaining digits are recorded in a manner similar to that described. The thousands digit 5 is recorded on the condensers of the group including condensers 254 to 251, inclusive, by fully charging these condensers and then discharging condensers 255 and 251. The hundreds digit 6 is recorded on the condensers of the group including condensers 258 to 261, inclusive, by fully charging these condensers and then discharging condensers 258 and 26L The tens digit 1 is recorded on the condensers of the group including condensers 262 to 265, inclusive, by fully charging these condensers and then discharging condensers 263 and 265. The units digit 8 is recorded on the condensers of the group including condensers 400 to 403, inclusive, by fully charging these condensers and then discharging condensers 400, 40I and 403.

Thus, at the termination of the transmission of the units digit impulses, relays 201, 208, 209 and 2 I 0 are all deenergized and transfer relay 409 is operated, all preceding transfer relays 200 to 206, inclusive, and 408 having been released in the manner previously described. During the reception of the heavy positive pulse, relays 201 and 208 operate in succession in the manner previously described. Relay 201 upon operating closes the operating circuit for transfer relay 4I0 extending from ground on conductor 228, lower front contact of relay 261, conductor 232, lower front contact of relay 409, winding of relay M0 to battery. Upon the operation of relay 208 the looking circuit of relay M0 is first closed followed by the opening of the locking circuit of relay 409 which now releases. The heavy positive pulse may be employed in the usual manner to cause the operation of relay 2E5 to transfer the inpulsing circuit from the relays 2I2, 2I3 and 2I4 to a holding circuit.

Transfer of office designation to the decoder When transfer relay 204 operated during the recording of the stations digit, a circuit was also established in parallel with the winding thereof over conductor 266 to battery through the winding of decoder connector start relay 5I6. In the well-known manner relay 5I6 establishes the circuit of multi-contact relay 5I1 which is individual to the sender. In the well-known manner relay 5I8 which is individual to the decoder of Figs. 5 to 10, inclusive, is operated. The operation of relays 5I1 and 5I8 now connects the receiving and transmitting conductors of the sender to the corresponding receiving and transmitting conductors of the decoder.

Prior to the seizure of the decoder relay 504 should be locked operated and relay 5I3 should be released in a manner to be hereinafter described, indicating that the prime relays 505 to 5I2, inclusive, of the tandem units receiving register, 605 to 6I2', inclusive, of the tandem tens receiving register and 655 to 662, inclusive, of the tandem hundreds receiving register are locked operated under the control of their associated polarized relays 565 to 5i2, inclusive, 605 to 6I2, inclusive, and 655 to 662, inclusive.

Upon the seizure of the decoder the receiving conductors are extended from the groups of condensers comprising the A, B and C code registers of the sender upon which the office code letters have been recorded, through the windings of the polarized relays of the receiving registers of the decoder to ground through a resistance, and also to battery through a resistance, and the transmitting conductors are extended from the groups of condensers comprising the district brush and group and office brush and group selection registers of the sender through the windings of the test relays 80I to 804, inclusive, of the office group register of the decoder, 90I to 904, inclusive, of the district group register, IBM to I003, inclusive, of the office brush register and I05I to I053, inclusive, of the district brush register.

At oil-normal contact 5I4 ground is connected to conductor 5I5, thence over back contacts of relay 800 through the windings of relays 80I' to 804', inclusive, of the office group register to battery, over back contacts of relay 900 through the windings of relays 90I to 904, inclusive, of the district group register to battery, over back contacts of relay I000 through the windings of relays IO0I to I003, inclusive, of the oflice brush register to battery, and over back contacts of relay I050 through the windings of relays I05I' to I053, inclusive, of the district brush register to battery These relays operate and lock under the control of their associated relays. For example, relay 86! locks in a circuit from battery through its winding and inner lower front contact, back contact of relay Bill to ground at the lower front contact of relay 80I. The decoder is now conditioned to receive the ofi'ice code record from the sender, to decode it and transfer the decoded information back to the sender.

It will be recalled that in recording the code letter C, condensers 2I8 to 22I, inclusive, were all charged and then condenser 2I9 was discharged. With the receiving conductors extended to the decoder, condenser 2I8 now discharges in a circuit from ground therethrough, conductors 261 and 561, windings of polarized relays 655 and 656 in series, resistance 604 to ground causing relay 655 to momentarily operate. Relay 656 does not operate since the discharge current from condenser 2I8 through its winding is not in the proper direction. Condenser 2I9 charges in a circuit from ground therethrough, conductors 268 and 568, windings of polarized relays 651 and 658 in series, resistance GM to battery causing relay 658 to momentarily operate. The charging current is not, however, in the proper direction to operate relay 651. Condenser 220 discharges in a circuit from ground therethrough, conductors 269 and 569, windings of polarized relays 659 and 660 in series, resistance 604 to ground causing relay 659 to'momentarily operate. The discharge current is not, however, in the proper direction to operate relay 660. Condenser 22I discharges in a circuit from ground therethrough over conductors 278 and 510, windings of polarized relays SM and 662 in series, resistance 604 to ground causing relay 66! to momentarily operate. The discharge current is not, however, in the proper direction to operate relay 66L If the four receiving circuits just traced are operative and relays 555, 658, 659 and 66! operate as described, the locking circuits of the associated prime relays 655, 653, 559 and 65V are opened at the back contacts of relays 555, 658, 659 and 65!. Relay 655' thereupon releases and as soon as relay 555 releases, which it does as soon as the discharge current from condenser 2i 8 through its winding ceases, closes a circuit for relay BB extending from battery, winding of relay 650, left back contacts of relays 655' and 555 to ground. Relay 658 releases upon the operation of relay 558 and as soon as relay 658 again releases when the charging current through its winding and condenser 2|9 ceases, closes a circuit for relay 65| extending from battery, winding of relay 65l, right back contacts of relays 658' and 558 to ground. In a similar manner relays 652 and 555 are operated upon the release of relays 659 and B59 and 66I' and 66!, respectively. The operation of relays 650 to 653, inclusive, is indicative that the recorded A code letter registration has been transferred to the tandem hundreds receiving register of the decoder. The operated condition of relays 655, 660 and 662 and the release of relay 658' records the tandem hundreds code letter C.

It will be recalled that in recording the B code letter I-I condensers 234 to 231, inclusive, were all charged and then condenser 236 was discharged. With the receiving conductors extended to the decoder, condenser 234 now discharges in a circuit from ground therethrough, conductors 2H and 571i, windings of polarized relays 605 and 695 in series, resistance M5 to ground causing relay 555 to momentarily operate. Relay 685 does not operate since the discharge current from condenser 234 through its winding is not in the proper direction. Condenser 235 discharges in a circuit from ground therethrough, conductors Eli and 5'32, windings of polarized relays Gill and SE38 in series, resistance M5 to ground causing relay Bel to momentarily operate. Relay 608 does not operate since the current through its winding not in the proper direction. Condenser 235 charges in a circuit from ground therethrough over conductors 2'53 and 513, windings of polarized relays 559 and 5m in series, resistance 555 to battery causing relay Bill to momentarily operate. Relay 559 does not operate since the charging current through its winding is not in the proper direction. Condenser 23? discharges in a circuit from ground therethrough, conductors N4 and 514, windings of polarized relays 6H and M2 in series, resistance M5 to ground causing relay 6 to momentarily operate. Relay M2 does not opcrate since the discharge current through its winding is not in the proper direction.

If the four receiving circuits just traced are operative, relays 555, 68?, till and 5H operate, as described, and the locking circuits of the associated prime relays 5E5, 55?, Eli) and 5H are opened at their back contacts. Relays Silt to 6&3 should now operate in circuits extending over back contacts of relay M35", 687, Sit and SH and back contacts ofrelays $05, 601, 6H) and 5H as soon as the latter relays release after their momentary operation. The operation of relays 500 to 503, inclusive, is indicative that the recorded B code letter registration has been transferred to the tandem tens receiving register of the decoder. The operated condition of the prime relays 6B6, 608 and BIZ and the release of relay 610' records the tandem tens code letter H.

In recording the C code digit 3, condensers 244 to 241', inclusive, were all charged and then condensers 244 and 245 were discharged. With the receiving conductors extended to the decoder, condenser 244 now charges in a circuit from ground therethrou'gh, conductors 215 and 515, windings of polarized relays 555 and 5315 in series, resistance 549 to battery causing relay 505 to momentarily operate. Relay 555 does not operate since the charging current through its winding is not in the proper direction. Condenser 245 charges in a circuit from ground therethrough over conductors 216 and 515, windings of polarized relays 501 and 588 in series, resistance 519 to battery causing relay 5638 to momentarily operate. Relay 5!" does not operate since the charging current through its winding is not in the proper direction. Condenser 245 discharges in a circuit from ground therethrough, conductors 2H and 511, windings of polarized re lays 559 and 5H1 in series, resistance 52!! to ground causing relay 509 to momentarily operate. Relay Eit does not operate since the discharging current from condenser 245' through its winding is not in the proper direction. Condenser 241 discharges in a circuit from ground therethrough over conductors 218 and 518, windings of pol-arized relays 5H and 5P2 in series, resistance 520 to ground causing relay 5H to momentarily opcrate. Relay 5i2 does not operate since the discharge current from condenser '24! through its winding is not in the proper direction.

If the four receiving circuits just traced are operative and relays 505, 558, 509 and 5!! cperate as described, the locking circuits of the associated prime relays 5562538, and 509 and 5| I are opened at their back contacts. Relays 500 to 5&3 should now operate in circuits extending over the back contacts of relays 5'96, 508", 559' and 5H and back contacts of relays 555, 558, 559 and 5!! as soon as these relays release after their momentary operation. The operation of relays 500 to 593, inclusive, is indicative that the recorded C code digit registration has been transferred to the tandem units receiving register of the decoder. The released condition of relays 5G6 and 558" and the operated condition of relays 5H3 and 5:2 records the tandem units code digit 3.

If relays 505 to 563, inclusive, 6% to 603, inclusive, and 656 to 553, inclusive, are all operated indicating that no receiving conductor was open, crossed with battery or ground, or that no condenser was broken down or leaking excessively, the locking circuit of relay 594 extending over the serially connected back contacts of these relays 'is opened thereby releasing relay 5%. at the front contact of relay 655 serially through the contacts of the others of these relays, offnormal contact 52L winding of relay 522 to battery. Relay 522 operates and locks to oiT-normal ground on conductor 5i 5 and extends ground from conductor 5l5 to conductor 524 and thence by branch 525 to the inner right armature of relay 5! I and by branch 526 to the inner right armatures of relays 6H and Three circuits are now closed as determined by the operated A circuit is now established from ground and unoperated condition of the prime relays of the tandem hundreds, tandem tens and tandem units registers of the decoder. The first of these circuits extends from ground on conductor 526 over the inner right back contact of relay 66I, inner right back contact of relay 650, inner right front contact of relay 651, outer right front contact of relay 656, winding of relay 100 to battery operating multi-contact relay 100. A second of these circuits extends from ground on conductor 52?, inner right back contact of relay BM, inner right front contact of relay 608, conductor 6", windings of relays WI and 102 in parallel to battery. The third of these circuits extends from ground on conductor 525, inner right back contact of relay |I, inner right back contact of relay 580, inner right front contact of relay 501, outer right back contact of relay 506, conductor 521, neXt-to-outer contact of relay L conductor 103, contact of relay 100, winding of route relay 186 to battery. Route relay 104 upon operating prepares circuits for set ting the selection registers shown in part in Figs. 8, 9 and 10 as will be hereinafter described.

Relay 522 upon operating also establishes a cirsuit from ground on conductor 5I5, over conductor 523, thence in parallel through the windings of relays 800, 000, I000 and I050 to battery. These relays now operate opening the initial operating circuits of relays 80 I to 804, inclusive; 90I to 904', inclusive; IO0I to I083, inclusive; and I05I' to I053, inclusive. These relays, however, being locked do not release. At its front contacts relay 800 connects battery through resistance 805 to conductor 806 and ground through resistance 801 to conductor 808 for the purpose of restoring the condensers of the A, B and C code registers of the sender to the condition in which they were prior to the transference of the registrations therefrom to the receiving registers of the decoder and for the purpose of reoperating the same polarized relays of the receiving registers of the decoder as previously operated. This is done as a furthercheck on the correct functioning of the decoder.

For reconditioning the condensers of the A code register of the sender the following circuits are established: From ground on conductor 800 over the left back contact of relay 658 through the winding of relay 658 and resistance 6I4 to battery and over conductor 568, thence as traced to ground through condenser 2 I9, thus discharging this condenser and operating relay 658; from battery on conductor 806, over the outer right back contacts of relays 655, 659 and 66I, through the windings of relays 655, 659 and 66I and resistance 604 to ground and over conductors 561, 569 and 510, thence as traced to ground through condensers 2I8, 220 and HI thus recharging these condensers and operating relays 655, 659 and 66L For reconditioning the condensers of the B code register of the sender the following circuits are established: From ground on conductor 808 over the left back contact of relay 6!!! through the winding of relay 650 and resistance M6 to battery and over conductor 513, thence as traced to ground through condenser 236 thus discharging this condenser and operating relay 6I0; from battery on conductor 806 over the outer right back contacts of relays 605, 601 and 6H through the windings of relays 605, 681 and 6| I and resistance 6I5 to ground and over conductors 51I, 512 and 514, thence as traced to ground through condensers 234, 235 and 231 thus recharging these condensers and operating relays 605, 601 and 6.

For reconditioning the condensers of the C code register of the sender the following circuits are established: From ground on conductor 808 over the left back contacts of relays 506 and 508 through the windings of relays 506 and 508 and resistance 5 I 9 to battery and over conductors 515 and 516, thence as traced to ground through condensers 244 and 245 thus discharging these condensers and operating relays 506 and 508; from battery on conductor 800 over the outer right back contacts of relays 508' and 5| I, through the windings of relays 509 and 5H and resistance 520 to ground and over conductors 511 and 518, thence as traced to ground through condensers 246 and 241 thus recharging these condensers and operating relays 509 and 5| I.

Since relays 506, 508, 509, 5| I, 605, 601, 6|0, 6| I, 655, 658, 659 and 66! are all operated at the same time and open the circuits over which relays 500 to 503, 600 to 603 and 650 to 653 have been held operated, these latter relays all release and establish the chain circuit from ground at the right back contact of relay 050 over the right back contacts of these relays to conductor 528, which circuit is completed through the winding of relay I004 if the selection registers of Figs. 8 to 10, inclusive, have already functioned.

It will be recalled that as a result of the transference of the office code registration to the receiving registers of the decoder, the route relay 184 Was operated. It will be assumed that the operation of this relay is indicative that the call should be routed. to a full mechanical office over a district and an ofiice selector and that therefore the following circuits are established by relay 104 for relays of the selection registers of the decoder: (1) from ground over conductor 105, distributing frame 809, conductor 8 I 0, upper winding of office group register relay 8I3, winding of relay 8| 6 to battery. Relays 8I3 and 8| 6 both operate; (2) from ground over conductor 106, distributing frame 905, conductor 906, lower winding of district group register relay 9 I 0, winding of relay 9I1 to battery. Relays M0 and 9| 1 both operate; (3) from ground over conductor 101, distributing frame I005, conductor I006, upper winding of office brush register relay I 0I I, winding of relay IOI2 to battery. Relays I0 and I0 I 2 both operate; (4) from ground over conductor 108, distributing frame I055, conductor I 056, upper winding of district brush register relay I958, Winding of relay I062 to battery. Relays I058 and I062 both operate. Relay 106 would also establish circuits for the relays of the usual class and compensating resistance registers. As these registers function in the usual manner they have been omitted from the present disclosure.

Setting selection registers of the sender As soon as the selection registers receive their settings from the route relay 104, if at that time ground has been connected to conductor 528 as previously described, a circuit is established from this conductor, upper front contacts of relays 80 I to 864, inclusive, upper contacts of relay 8 I3, conductor 8|8, upper front contacts of relays Bill to 904, inclusive, upper front contact of relay 9|0, conductor 0I0, upper front contacts of relays I00! to I003, inclusive, upper contacts of relay I0| I, conductor |0I4, upper front contacts of relays I05I to I053, inclusive, upper contacts of relay I058, thence in a chain circuit through contacts of relays of the compensating resistance and class registers, not shown, to. battery through the winding of relay I004. Relay I004 operates and locks over its lower front contactto ground on conductor M5 and at its upper contact opens: a potentiometer circuit including resistances. I I5. and IOI0, thus changing the potential on all of the transmitting conductors extending from the decoder to the condensers of the selection control registers of the sender from an intermediate potential, which was applied thereto. immediately upon the connection of the decoder with the sender, to either battery or ground potential dependent upon the operated or non-operated condition of the selection register relays. Thus, for example, immediately following the seizure of the decoder, intermediate potential was applied from the midpoint of the potentiometer (grounded battery through resistance IOI6, back contact of relay- I004, resistance I0l5 to ground), back contact of relay I058, lower back contact of relay I080, winding of relay II, conductors 553i and 43I through condenser Hi to ground thus charging condenser 4!! to the intermediate potential. In a similar manner the remaining condensers M8 to 430, in-

clusive, of the selection control registers are charged to the intermediate potential.

When relay I004 operates as previously described with relay I050 of the district brush register operated and the other relays I059, I060 and I06I of this register unoperated, the following circuit conditions over the transmitting conductors extending from the district brush register of the decoder to the district brush register of the sender are effective: From ground through resistance IOI5, front contact of relay I058, lower back contact of relay I080, winding of relay I05I, conductors 53I and 43I through condenser 4I'I to ground resulting in the discharge of condenser 4H and the momentary operation of relay I55I; from battery through resistance IOI5, back contact of relay I059, inner lower back contact of relay I050, winding of relay I052, conductors 532 and 432 through condenser M0 to ground resulting in the further charging of condenser M8 and the momentary operation of relay I052; from battery through resistance IOII5, back contact of relay IO0I, winding of relay I053, conductors 533 and 433 through condenser 4I0 to ground resulting in the further charging of condenser 4I9 and the momentary operation of relay I053. The momentary operation of relays I05I, I052 and I053 releases relays I05I, I052 and I053, respectively. The district brush registration has now been recorded in the sender by the discharged condition of condenser M1 and the charged condition of condensers M8 and M9.

It will be recalled that relay 9I0 of the district group register was operated and that the other register relays of this register were unoperated. Following the operation of relay I004 the following circuit conditions over the transmitting conductors extending from the district group register of the decoder to the district group register of the sender are effective: From ground through resistance IOI5 over conductor Illi'l, lower front contact of relay 9I0, lower back contact of relay 9I3, back contact of relay 0I5, winding of relay 90L conductors 534 and 434 through condenser 420 to ground resulting inthe discharge of condenser 420 and the momentary operation of relay 90I from ground through resistance IOI5 over conductor IIiII, inner lower front contact of relay 910, lower back contact of relay 9M, inner lower back contact of relay 920, winding of relay 902, conductors 5'35 and 435 sistance IOI0. over conductor I,0I8;, back contact.

of relay 9H, lower back contact of relay SIG, winding of relay 903i, conductors 536. and 436 through condenser 422 to: ground resulting in the further charging of condenser 422 and-the momentary operation of relay 903:; from battery through resistance I0 I 6 over conductor I018, back contact of relay 0I2, inner lower back contacts. of relays. 91:3; and 0M, lower back contact of relay inner lower back contact of relay 906, winding of relay 9.0.4, conductors; 531 and 43:1, condenser 423 to ground resulting in the furthercharging of condenser 423 and the momentary operation of relay 304.. The momentary operation of relays 00I to 9.04., inclusive, releases relays 90! to 904, inclusive. The district, group registration has now been recorded in the sender by the discharged condition of condensers 42.0; and 42I and the charged condition of condensers 4.22 and 4.23.

Since relay IOI I of the ofiice brush registerrwas.

operated and the remaining register relays of the register are unoperated the following circuit, conditions over the transmitting conductors extend-- ing from the office brush register of the decoder to the ofiice brush register of the sender are effective following the operation of relay I004: From battery through resistance IOI5 over conductor IOI8, back contact of relay I008, lower back contact of relay I010, winding of relay I1010I conductors 530 and 43-8v through condenser 424 to ground resulting in the further charging of condenser 424 and the momentary operation of relay IO0I; from battery through resistance I018, over conductor IOI8, back contact of relay I009, inner lower back contact of relay I010, wind ingof relay I002, conductors .539 and 439 through condenser 425 to ground resulting in the further charging of condenser 425 and the 'rnomentary' operation of relay I002; .from ground through resistance IOI5 over conductor IOI'l, lower front. contact of relay IOII, winding of relay I003, conductors 540 and 440 through condenser 420 to ground resulting in the discharge of condenser 426 and the momentary operation of relay I003. The operation of relays IO0I to I003, inclusive, re-

leases relays IO0I to I003, inclusive. The office brush registration has now been recorded in the sender by the charged condition of condensers 424 and 425 and the discharged condition of condenser 428.

Since relay 8I3 of the oflice group register was operated and the remaining register relays of this register are unoperated, the following circuit conditions over the transmitting conductors extending from the ofiice group register of the decoder to the office group register of the sender are effective following the operation of relay I004: From battery through resistance IOI6 over conduotor IOI0, back contact of relay 8I2, lower back contact of relay 8I4, winding of relay 80I, conductors 54I and MI through condenser 421 to ground resulting in the further charging of condenser 42! and the momentary operation of relay 80!; from ground through resistance IOI5 over conductor IOII, lower front contact of relay 8 I 3, inner lower back contact of relay 8 I4, winding of relay 802, conductors 542 and 442 through condenser 428 to ground resulting in the discharge of condenser 42.8' and the momentary operation of relay 802; from battery through resistance IOI6 over conductor IOI8, back contact of relay 8I5, winding of relay 803, conductors 543 and 443 through condenser 429 to ground resulting in the further charging of condenser 429 and the momentary operation of relay 893; from battery through resistance IOI6 over conductor I0 I8, back contact of relay 8| 1, winding of relay 804, conductors 544 and 444 through condenser 430 resulting in the further charging of condenser 430 and the momentary operation of relay 864. The operation of relays I to 804, inclusive, releases relays 80I to 894, inclusive. The ofiice group registration has now been recorded in the sender by the discharged condition of condenser 428 and the charged condition of condensers 421, 429 and 430.

When all of the relays 80I' to 804', inclusive, I to 904', inclusive, IO0I to I003, inclusive, and I05I' to I053, inclusive, have been released, a circuit is closed from ground on conductor 5I5, front contact of relay I004, lower back contact of relay I 05 I back contact of relay I05 I, inner lower back contact of relay I05I and in a similar manner over back contacts of the other transmitting relays and finally to battery through the winding of decoder disconnect relay 8I9. I-Iad there been an open, cross with battery or ground, breakdown or excessive leakage on ,a condenser, the circuit of relay I3I9 would not have been effective and a trouble release alarm signal would be sent in the usual manner. When relay 8I9 operates causing the release of the decoder connector, all of the transmitting ,and receiving conductors are opened and relays 522, 800, 900, I600, I004 and I550 release. When relay 800 releases and removes battery and ground from conductors 866 and 808 the polarized relays, which operated as previously described during the reconditioning of the code registers of the sender, are released causing the operation of all relays 500 to 503, inclusive, 600 to 603, inclusive, and 650 to 653, inclusive. For example, upon the release of polarized relay 506, relay 500 operates in a circuit from battery through its winding, inner right back contact of relay 506 and the back contact of relay 506 to ground. With these relays all operated a chain circuit is closed from ground over their front contacts, the normally closed contacts of contact set 52I, winding of relay 545 to battery. Relay 545 operates and looks over its outer front contact to ground at the normal contacts of relay 564 and extends its own operating ground through the winding of relay 5 I 3 which also operates. Relay 5I3 upon operating connects ground to conductors 546 and 541 causing the operation of all of the prime relays of the receiving registers of the decoder, these relays locking under the control of their associated polarized relays. For example, relay 505 locks in a circuit from battery through its winding and inner left front contact, back contact of relay 505 to ground. With the prime relays all operated, relays 506 to 503, inclusive, 600 to 603, inclusive, and 650 to 653, inclusive, release closing ,a chain circuit from ground over their back contacts, left front contact of relay 545, winding of relay 504 to battery. Relay 504 upon operating first looks over its front contact to ground supplied over this chain circuit and then opens the locking circuit of relay 545 which now releases in turn releasing relay 5 I 3. The remaining operated apparatus of the decoder is released in the usual manner and the decoder is now in condition for serving the next call.

Establishment of full mechanical call It will be assumed that with the complete information for. controlling the establishment of the connection now registered in the sender, relay H9 is operated and then released. Upon operating it closes the circuit of relay H8 and, since it will be assumed that the registered information concerns a full mechanical connection, operating circuits are also closed through the upper Winding of selection control relay II4, the upper back contact of relay I24 to battery. Similar circuits are closed for the selection control relays H5, I I6 and H1. These relays will operate, relay II8 preparing operating circuits for relays I24 to I21, inclusive. With the transfer relay 4I0 operated, as previously described, the following circuits are now effective: (1) From ground through condenser 4 I I, the upper contact of relay 4 I I), couductor 239, upper front contact of relay 201, conductor 219, winding of relay I24 to ground at the upper contact of relay H8, but without effect as condenser M1 is uncharged; (2) from ground through condenser 4I8, next-to-upper contact of relay 4I0, conductor 240, inner upper front contact of relay 201, conductor 280, winding of relay I25 to: ground at the upper inner contact of relay H8. Since condenser 4I8 is in a charged condition it will now discharge operating relay I25 which looks to battery over its front contact and at its back contact opens the operating circuit of relay I I5 which releases; (3) from ground through condenser 4I9, next-to-inner upper contact of relay 4I8, conductor 24I, upper front contact of relay 208, conductor 28I, winding of relay I26 to ground ,at the inner lower front contact of relay I I8. Since condenser M9 is in a charged condition, it will now discharge operating relay I26 which looks to battery over its front contact and at its back contact opens the operating circuit of relay II6 which releases; (4) from battery over the inner upper contact of relay 4I0, conductor 242, inner upper front contact of relay 258, conductor 282, Winding of relay IZ'I to ground at the lower contact of relay H8. Relay I21 operates, looks over its front contact and at its back contact opens the circuit of relay I I! which now releases.

As soon as relay H9 releases, locking circuits are first established for all operated relays I I4 to I I1, inclusive, and then theinitial operating circuits of these relays and relay H8 are opened. Relay II8 releases followed by the release of any operated relays I24 to I21, inclusive. As the result of these operations relay H4 remains operated upon the release of relay H9 and the re maining selection control relays are unoperated.

The release of relay I I9 establishes the operating circuit of relay I I2 which supplies locking ground to the counting relays and closes the fundamental circuit which may be traced in part from conductor I2I over the upper contact of relay I I2, lower back contact of counting relay I38, winding of stepping relay I23, conductor I22 thence through the winding of the control relay of the district selector (not shown). The control relay of the district selector and the stepping relay of the sender both operate over this circuit.

The control relay of the district selector starts the brush selection movement of the selector switch shaft in the well-known manner, and relay I23 establishes a circuit from ground, upper back contacts of selection control relays H1, H6 and H5, upper front contact of relay II4, lower back contact of counting relay I3I, winding of relay I4I to battery. Relay I4I operates and locks in series with relay I3I over the front contact of relay Hi to ground at the front contact

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