US2333195A - Key pulsing sender for telephone systems - Google Patents

Description

Nov. 2, 1943. w. PQULIART KEY PULSING SENDER FOR TELEPHONE SYSTEMS Filed March I50, 1940 3 Sheets-Sheet 1 u mi 3 A Il'llll ll INVENTOR W n. FOUL/ART ATTORNEY FIG. 2

Nov. 2, 1943. w. POULIART 2,333,195

KEY PULSING SENDER FOR TELEPHONE SYSTEMS I Filed March so, 1940 s Sheets-Sheet 2 LP/O LK/O 0 0 LP2 LKZ lNl/ENTOR By M. POUL MR7 m .47 Tom/Er Nov. 2, 1943. w. POULIART 2,333,195 I KEY PULSING SENDER FOR TELEPHONE SYSTEMS Filed March 30, 1940 3 Sheets-Sheet 5 INVENTOR B W POUL/ART Patented Nov. 2, 1943 KEY PULSINGUSENDER FOR TELEPHONE SYSTEMS Willy Pouliart, Antwerp, Belgium, assignor, by mesne assignments, to International Standard Electric Corporation, a corporation of Delaware "Application March 30, 1940,Serial No; 326,864

In Great Britain April 4, 1939 9 Claims.

This invention relates to electrical character storage and transmission equipment.

It is particularly adapted for use :in key controlled impulse. sender equipment and register controllers for telephone exchange systems but is not limited in its. application thereto.

The equipment may be arranged to control the forward transmission of characters or to exercise control in response to signals transmitted thereto from equipment to be controlled, as for instance, in a register, of thekind used in the rotary system of automatic telephony.

The objectof the invention isto provide cheap and reliable equipment ofthe above type.

The main feature of the invention comprises an electrical character storage and-transmission equipment characterized by'groups of condensers for storing different characters, meansfor transferring the characters in turn from the condenser group to an electromagnetic rcontact-making marker device arranged to control the value of impulse combinations transmitted from or: to the equipment.

The invention will be clearlyunderstoodfrom the following description ofone embodiment shown in. the accompanying drawings in which:

Fig. 1 showsa telephone operator's key-set together witha number indicator;

Figs. 2..and 3 together'show digit storage and. transmission equipment. :Fig. :3 should be placed' below Fig. 2. a

nWhen aprivate automatic branch exchange"at tendant wishes to originate an outgoing city call, ShelthI'OWS the answering'keyof the cordor trunk over-which the callris goingto be set up. The fact'that the aforementioned key is thrown,'.busies the attendants key sending,registercircuit and a signaling. lamp BL is made to light indicating that the. register is ready, for the reception of digits. the other, the keys correspondingtothe wanted subscribers number and after the complete insending is finished, she depresses a startingkey in order to cause impulse trainscorresponding to the aforementioned number-to be' sent out towards the exchange.

During the time that impulses are 'being sent out, the signaling lamp BL is mad to li'ght dimly. The full relighting: of lamp DL afte 'thedeprea sion' of the starting key thusindicatesthat 'the complete number which was keyed hasbeenretransmitted. i

When, after the call. has been .set up, the answering key is restoredto normal,1amp'DL is The attendant thendepresses one-after.

extinguished and the key sending register is available fora new call.

In case a number of prefix keys are provided in addition to the ordinary digit keys, the attendant, inorder to reach a subscriber belonging to an exchange area characterized by a given prefix, may depressthe prefix key corresponding to that area and then send in by means of the digit keysthe local number-of the: subscriber; the attendantcan, however, also reach the same subscriber by keying up the complete number by means of the digit keys. .Ifrequired, a signaling lamp may be associated with eachprefix key in order to provide a means of checking, during the setting up of the call the direction which has been picked up.

The restoration of the answering key at any moment during the setting up of a call immediately releases the key sending register which returns tonormal and thus becomes available for a new call.

The. connection of the attendants key sending register and key-set to a private automatic branch exchange only requires the opening up of the a and b wires to the attendantspositional circuit in order to insertthe register in series with the dial, and the connection of one wire towards the answering key of the trunks or cords in order to receive an indication when an answering key is depressed. In case there is no Contact available on the answering keys, it is gen-' erally possible to obtain th same indication by adding a common pilot relay in series with a circuit controlled from one of the existing make contacts on the answering keys.

Although the attendants keysending register is inserted in the a and b wires of the attendants positional circuit, the aforementioned wires remain normally closed when the register circuit is not in use, Sothat the attendant may in case of circuit failure, use-the dialinstead of the key-set without-having to effect any special oper ation for the purpose.

The operation of the circuit is such that whenever the starting-key-is depressed after a number of digits have been keyed, the corresponding impulses are sent out on the line and impulsing stops automatically after out-sending of the.

. train corresponding to the last digit keyed. The line then remains closed towards the exchange the case of a dial and the circuit is restored to the conditions existing before the digits had been keyed. This last-mentioned feature .makes the register circuit also suitablefor opennumbering systems, where the complete subscribers number may have to be transmitted in two or more parts, each part being sent out after reception of a new dialing tone; in that case, the attendant must, after the reception of each dialing tone, key up and send the corresponding part of the subscribers number.

The circuit has been designed for a capacity of II digits, that is, it is possible to key an 11- digit number and retransmit the aforementioned number by a single depression of the starting key,

The storing of the digits keyed by the attendant is based on the condenser charge principle, four condensers being required for each digit stored.

The register circuit is provided with three terminals for connection of a number indicator by means of which it is possible to check the number which is effectively sent outin the form of impulse trains.

The number indicator is of the type comprising a number of indicator wheels arranged to be set in turn by common stepping mechanism which is shifted from wheel to wheel'between digits received. It comprises a Stepping magnet and a shift magnet and simultaneous .operation of the magnets causes all the indicator Wheels to be horned.

S'WITCH 'AND RELAY FUNCTIONS The register circuit comprises a switch S of the marker type used a distributing switchior the successivedigits keyed. The sameswitch is also used as distributing switch during the transmission of the successive'impulse trains corresponding to the digits received and storedon Reception of digits keyed on number kegs When, the attendant throws the answering key AK of a trunk or cord circuit TC over which a call is to be set up, battery is connected to lead No. '7 in the key-set and causes the energization of relay B in the register circuit, battery,,winding of B, bi, nit-wipers sma and ssma in home positions, ground.

Relay B once energized locks todirect groundvia 174 before opening its energizing circuit, and introduces the following conditionsin the circuit:

(1) A full'ground via ssii, bl isconnected to terminal Lc in order to light the signaling lamp DL of the number indicator NT thusindicating that the key sending registeris ready for reception.

(2) A circuit is completed for energizing relay D in series with the winding of the switch magnet SM via b2, rd3, interrupter and winding of SML The resistance of relay Dis such, however, that the power magnet SM of the switch S is not energized.

(3) Via b3 and b5, relay 1% gives respectively the general battery and ground required for further circuit operations. Y

( l) Contacts b6 disconnect the ground which may be required for restoring switch SS on a premature release.

Reception of first digit When the digit key corresponding to the first digit is depressed, a ground is given on lead L whichever key is depressed for energizing the marker switch magnet SM and battery is connected to certain of the wires Ll to L4 in ac cordance with a code combination corresponding to the keyed digit. The combinations used are as follows: digit 1, battery on LI; digit 2, battery on LI and L4; digit 3, battery on LI, L3, L4; digit 4-, battery on LI, L3; digit 5, battery on L3; digit 6, battery on L2, L3; digit 7, battery on L2; digit 8 battery on Li, L2; digit 9, battery on L l; digit 0, battery on L2, L4,

Relays Am, Bm, Cm and Dm energize in accordance with the battery connections on terminals Ll, L2, L3 and L4 via p02, smb, smc, smd

and mm, respectively.

During the time that the digit key is maintained depressed and magnet SM is operated, relay D is short-circuited and deenergizes thus removing the earth shunts which would otherwise be connected to relays Am, Bm, Cm and Dm. The operated relays lock via their contacts 2, 1'32, 173.

At the moment the digit key is released, the marker switch S makes one step and when its interrupter. is reclosed, relay D reenergizes in series with the marker switch magnet SNI.

Reception of the second digit At the moment relay D has reclosed its make contacts, and switch S is standing in position 1, the condenser connected to terminal 1 of arc smb is charged as follows: battery d4, ss2, pc'l, smb, dl, earth.

The other three condensers connected to arcs smc, smd, sme infposition: I are charged in similar circuits. 5

When the digit key corresponding to the second digit is depressed, the power magnetSM is energized as explained previously for the first digit and relay D releases.

When, however, relay D has closed its break contacts the condensers connected to certain of the leads LI, L2, L3, L4 willbe charged in the opposite direction to the charge given previously by relay D provided that on the leads in question,

Reception of following digits The reception of all following digits is' similiar to thatdescribed for the second digit. In eachcase, charges are received on four condensers connected to corresponding terminals on arcs smb to sme. i Y

At the end of in-sending, switch S will therefore have made a number of steps equal to thenumber of digits which have been keyed, this number never exceeding eleven;

Reception of keyed prefix In case the wanted subscribers number cornprises a prefix corresponding to a :direction. .for

whichpan individual. key has been provided on the-,attendants key-set, and the attendant instead of =keying the .complete number on digit keys, sends in the number by means of the prefix key and digit keys, the circuit operation is modified as follows At, the moment onerof :theprefix keys PKI to PKIO, for instance PKL; isdepressed .on the attendants key-set, a ground isgiven for the energization of the corresponding relay Fri. and the common relay Fe in the register circuit. These relays energize in series and remain locked via pr! 6.

If ,we assume, for instance, that the prefixes comprise 3 digits, then the jumpering. between terminals g to k associated with the storage con denser groups and terminals Z to associated with the contact bank sma must be efiected. as shown dotted on the drawings, and the contacts 2, 3 and.

4 of ,the prefix relay Prl must be connected to the marking wires of bank ssma corresponding to the prefix digits, contact 2 controlling the marking for the first digit, contact 3 vfor the second digit and contact 4 for the third digit. A lamp PL! corresponding to prefix key PKI is energized via LP-l and prl I.

Whenrelay Pc is energized, switch SM is made,

torotate under the control of its own interrupter via 1112, p03 and p04 in parallel, contacts N, l, 2

of sma, ssma to earth.

The value of the three prefixdigits is stored by the energization of relay PM and switch S will therefore be rotated until terminal 3 is reached. Terminal 3 corresponds to the position in which the switch must be standing in order to receive the fourth digit of the subscribers number.

Relays Am, Bm, Cm, Dm remain deenergized and none of the condensers connected to. ter: minals l and 2 of arcs smb to sme are charged. Relay D remains deenergized as long as switch S has not reached position 3,-being short-circuited by. earth via ssma, sma, p03, rd2, rd3, b2.

At the. moment, however, the switch stops in position 3, relay D is made to operate in series with SM. and thefour condensers corresponding tothe fourth digit of. the number are. charged.

Depression of the digit key for the fourth digit releases D, operates SM andchanges the charge onv certain of the condensers of the group to store the digit as previously explained.

The reception of the following digits is made in exactly the same manner as thatdescribed previously for digits sent in by the digitkeys,

However, the storing of digits on the condensers starts from the thirdgroup of condensers correspondingto the fourth digit of the number.

Translation of stored digits .into impulse trains sentout towards the distant exchange When the attendant has finished keying the distant wanted subscribers. number, she depresses the starting key SK of her key-set thus causing the energization of relay Rd over lead L6. As soon as Rd has closed its make contacts, the marker switch S is restored to normal as follows: battery, winding SM, interrupter contact of SM, M3, 883 are and brush sma, normal terminal and brush smsa. to ground.

Switch S stops at normal, theresetting circuit being then opened at sma. At .this moment relay Ss; is energized via rdd, sma, ssma. Relay Ss once. deenergized locks via ss4, es2,- b5. Contacts ss3 open the resettingcircuit for switch-S. Relay Ss when energized introduces in the circuit The. opening of contacts 885 removes full ground fromcontacts bl, so that aresistanceis introduced in series with lamp DL in the keyset so that the lamp burns dimly indicating that selection has started,

Earth via ss5,,es4, prepares a circuit controlled by contacts il, which are not yet closed, via rs4 for SSM. On the other hand, from the moment the register circuit is busied, a circuit was com.- pleted in order to cause relays P, Ph: and Ito pulsate as described below.

Impulse generation At the moment relay B energized when the register circuit was seized, the condenser ON .in

and ground in the circuit of the condenser CN and disconnects .thelOO-ohm resistance HDR which was placed in parallel with the right-hand winding of PH At the same time the current in the left-hand windingv of P is reversed and has therefore a tendency to repulse the armature of P from the right contact spring.

However, the condenser CN which has been charged, over the break contacts of Ph must first of all discharge itself and to a certain extent charge itself in the opposite the right-hand winding of P (which is in opposition with the left-hand winding) before the relay P opens its right contact under the in fluence ofthe ampere turns in the left-hand winding.

When relay P opens its right contact, relays Ph and I release, and as soon as Ph recloses its break contacts, the conditions on relay P are reversed. The condenser CN discharges itself, and charges itself in the opposite direction, and the fiuxthus created in the right-hand winding of P issuch that the armature is repulsed from the rightcontact spring, whilethe current flowing in the left-hand winding of P has a tendency to reclose the right contact.

Relay Ph being deenergized, the discharge and charge of the condenserCN is effected over the righthand winding of P shunted by 100. ohms, and the 1000 ohms outside resistance, so. that aftera time shorter than the previous discharge time, relay P, recloses its right contact under the influence of the ampere turns in the left-hand winding.

The cycle starts over again. and relays Ph and I will create impulses, the period and break to make ratio being determined by the characteristics of the discharge circuits for the condenser in series with the right-hand winding of relay-P.

Although: at the beginning of the pulsations the timing may be different from that obtained after stabilized operation, it is ensured that after a very short number of cycles the timing becomesncrmal, and therefore at the moment switch SS is placed under the control of the make. contact. of I, the impulsing is already correct. I

direction through i Contacts i2 prepare ground for operating magnet STM of the number indicator NI. At the same time contacts phll preparethe opening of the line via the operators telephone set TS, La and Lb, key AK, towards the automatic exchange but this opening is not yet efiective because the line remains closed over contacts isl.

of impulse trains for digits which have beensingly keyed When relays I and Ph energize for the first time after the operation of S8, switch magnet SSM energizes, and when I and Ph release, SS makes one step and relay Is energizes over terminal I and brush ssma, Is immediately locks; spl, left-hand winding of Is, 2192, T32, b3. At the moment relay Is energizes, relay Ph is released so that the line still remains closed towards the distant exchange. When, however, relays I and Ph reenergize, thus preparing the next step of switch SS, the line is opened and one impulse is sent out. At the same time, one impulse is given towards the number display apparatus via i2, is4.

The switch SS makes a step on each closure of the line and when the position marked by the combination of relays Am, Bm, Cm and Dm is reached, relay Sp energizes in the following circuit; battery, winding of Sp, brush and arc ssmc, contacts of combination relays Am, Bm, Cm, Dm, one of leads 1 to 0, marked terminal in arc ssma, brush ssma, ground.

As soon as relay Sp is energized, it

Out-sending locks via ssmc, spl, at the same time opening the locking circuit for relay Is,'which deenergizes and recloses the outgoing line circuit permanently. The number of openings given on the line is therefore always equal to the number'of steps effected by the switch SS from position 1 until it reaches a marked wire.

Relay Rs energizes, and remains held in parallel with relay Sp.

Relay Rs when operated, causes the switch SS to rotate under the control of its own interrupter, opens the locking circuit for relays Am, Bm, Cm, Dm, and via rsl provides a ground for energizing switch magnet SM. Contacts 1's3 provide a ground via Le for energizing the shift magnet SHTJI of the number indicator NI.

When switch SS reaches position 17, the looking circuit for relays Rs and Sp is opened, SM therefore makes one step and the switch SS is replaced under the control or the make contact ii.

From position 17 to position 1, switch SS therefore again steps under the control of the impulse generating relays P, Ph and I. The time taken for effecting these steps corresponds to the minimum interdigit'al relay required and serves at the same time to check the state of the four condensers on which the second digit of the numher is stored, that is the four condensers connected to position 1 of switch S.

Checking of condenser charges Relay Ss energized after switch S had been reset at the beginning of out-sending and the high resistance lefthand winding of relay Do is thereby connected via ss2' to the common point of the storage condensers. On the other hand, when relay Rd energized to the start key SK shortly before $3, the operating circuit for relay Dwas opened at 1113 and ground was thus removed from the four leads connected to the brushes smb to sme. Atthe same time a ground is given via b5, cs2, rdl, to the armature of relay Dc thus causing the energization of relay Dh. Dh in turn causes the energization of relay Dc and the latter relay locks over its make contact before its operating circuit is opened owing to the release of relay Dh when the circuit for the latter is reopened at the break contact of Dc.

The above operations taking place before the first impulse train is sent out, it is ensured that at the moment that the first interdigital time is counted out relay Dc is looked under the control of its make contact and relay Dh is deenergized.

When switch SS reaches position 18, ground is connected to brush smb and thus completes a circuit for checking the charge of the first digit condenser in series with the high resistance winding of Dc; earth ssma in position 18, smb in position 1, condenser, pol, ss2, left-hand winding of Dc, battery.

If we assume that this condenser was charged under the control of a digit key, the charge is such that the potential on the condenser is in series-aiding with the potential of the circuit battery, the high resistance winding of relay Dc being connected to battery.

The current which flows momentarily over the high resistance winding of D0 will thus result from a discharge of the digit condenser placed in series with it, followed by a charge in the opposite direction so that the energy released by the condenser is the same as if it were a single discharge from a potential equal to twice that of the circuit battery. 7

The flux created by the discharge current is in opposition to the holding fiuX of the relay Dc and the value of this discharge flux is sufiicient to cause the resultant flux to pass below the holding value for relay Dc. Relay Dc deenergizes and causes the operation of relay Dh which in turn reoperates Dc, and the latter relay again opens the circuit for Dh as explained earlier.

Relay Dh remains on its make contact for a time ranging between 37 and 55 milliseconds.

these limits being the extreme values obtained with all possible variations of voltage andadjustment on relays Dh and Dc.

When relay Dh is energized, a circuit is closed for the energization of relay Am via ssmb in position 18, dhl.

Am immediately locks via am2, r82, b3.

The total time taken by the release of Dc, the operation of Dh, the reoperation of Dc and the release of Dh is always less than the time during which the switch SS remains on a same terminal, so that it is guaranteed that relays Do and Dh are ready to effect a new condenser check by the time that switch SS reaches position 19.

The cycle of operations described above is therefore repeated but this time it is the condenser connected to position 1 on are smc which is checked and in case it has been charged under the control of the digit key, it will cause the operation of relay Bm which is connected in position 19 of switch SS.

If we assume that the condenser had not been charged under the control of the digit key and has therefore been charged in the opposite direction under the control of relay D during the reception of the digits, no discharge current'can take place in the high resistance winding of De, the potential on the condenser being in opposition with the equal circuit battery potential.

Relay Dh therefore will not energize and the corresponding relay in the group Am, Bm, Cm and Dm will also remain deenergized.

When the marker switch SS has effected its fourxsteps 18 to 21,; under :thej-- control of the pulsating relay I; the state of; relays Am, BMJC'm andDm will correspond to the, digit storage condition-rot the four -condensers,-and arc ssmw is 'marked accordingly.

responding-to the second digit which had been I stored on the condensers'connected-to position 1 of. S, and "when switch =SS" reaches, the wire marked "by the combinationrelays Am, Bm; Cm and Dm itlagain runs to position 18 after-having caused S to step to positionl2. 1 The four conwzlen'sers'. corresponding. to the ithildidigiflwill be checked exactly as explained for the previous "digit','theidigit recorded on relaysAm to Dm-and so on.

Each digit isrecorded on the number indicator,

the shift magnet of 'whichis operated after-each digittransmission. Since every-digit is characterized .by at least on'econdenser charged in opposition to the others, i for each impulse train which thas to be sent out, at 'least onev of the combinationirelays will be energizedduring-the interdigital time preceding the train. It follows tha't. when switch SSreturns to normal while none of the relays Am, Bm; Cm

- and D111 have-beenenergized; this condition gives the indication that out-sending is finished. Relay'lEs is then made-to energize via dmLcml, bmlyaml, rd5,=pc4,larc andwipersma, ssma to earth. As soonas relay Es is energized, the holding circuits *for relays Rd and :Ss are openedat 682, but relay Es remains locked via esL-sma, ssma.

Switch S is then reset to normal viaits interrupter; rd3, b2,- 683. a When switch 8- reaches'its home position, re-

layEs is' unlocked ancl the circuit placed again in the same condition as when it was seized-before 'reception of the'digits. It is therefore possible whennecessary, for instance; in the case of an open numberingscheme, to send in a new series "of dig-its and cause these" digits-to'be repeated in the form ofimpulse trains towards the automatic e'xchange,-inthe same manner as explained previously.

*Whenmelay-Ss is released afull ground is reconnected towards lamp SL in the key-set, thus "indicating the end'of impulse transmission. Translationoj keyed prefix into impulse trains transmitted towards exchange If the attendant, when keyingthe distant wanted partys number-has made use of a prefix key characterizing the wanted direction orarea, the retransmission of im-pulse trainscorresponding to the prefix digits isefiected'as follows:

' At the =moment -the "starting key SK iswdepressed on the key-set,"relays Rd and Ss energize as explainedpreviously'and switch S is restored to' normal; *Relays Am, Bm, Cm and Dm, however, are all deenergizedsince-irifthe normal po- 'sition of S no-digit keyihas been rdepressed.

-Switch SS will start itorotate under :the con.- trol of the impulsingrelay L as explained pre- 'yiously, but the'marking circuit is: closed differently'rand may be traced 1 as follows: battery, windingofSp, brush andarc same, series ,break contacts (11113, 111723, bm3;=cm3; make contact is3, brush and are smb in normal position, make contaGtJZ-"Of the prefix relay Prl, which is operated, marking wire on are ssma, earth.

tion to terminal I. As soon as relay Is energizes,

the impulses corresponding to the second digit are sentout until the switch SS reachesagain a wire marked in'a-circuit via contact 3. of PM and brush smb in position 1.

It should be noted that, thedigit condensers connected in the various positions of S corresponding to the prefix digits, do-notin anyway interfere with the changed marking circuits, the

common point of these condensers being disconnected at the left outer break contact of relayPc.

o-ii normal, 'ssmanormal. I

- In order to avoid giving the end of digit transmission signal owing to the-fact that thefour combination relays Am, Bm, Cm and Dm remain deenergized during transmission I of the prefix digits, the circuit passingover the series break contacts aml to dml of the combination relays is opened at 1204 as;long as switch Shasnot reached position 3 correspondingto the-first digit which has been sent in-by means of a digit-key.

If we assume that} the prefix comprised, for instance, 3 digits-contacts 2, 3. and lot-the corresponding relay Prl are used. for marking purposes and the 3 digits aretranslated into'impulse trains as described above.

At the end of the third digit, however, switch Sreaches position 3 which corresponds to a set of condensers on which'the first digit set up by a number'key has been-stored. The operation of the circuit becomes then; the-same as that described for impulse transmissionof a number set upentirely by means of digit keys.

If position 3 is reached and-the corresponding storage condensers have all-beenchargedsolely underrthe control of relay DpDhus-indicatingthat the starting key has been depressed immediately after the depression of a prefixkeyrelayEsen ergizes as soon asswitch'SS returnsto normal after the third digit of C11 8-PlSfiX-haSbSSILSSHU out. The circuit is then restored to the initial conditions, and is ready to receiue a second setof digits.

When at the endwojimpulse-transmission, relay Es energizes,- 0 L '"lP Bing circuit 'for relays P0 and Bris-openwan i l gloufidfin lead LC for lighting the signalinglampDL is re placed via .ssB, thusv causing lamp. -DL -to burn brightly and give theend oi-selectionsignal.

In case a number indicator is used as lwehave assumed in the pres nt description, it' shows up the number which has been-effectively sent -:out. At the end of selection',.however,thenumber indicator .isinot restoredand the number will remain apparent until :the register circuit is used for setting up a new callor anew series of digits at the end of the impulse transmission. i The resetting of the number display apparatus is caused by thenenergization of relayDr duringthertime that the marker switch S is off-norinal,-; before the'starttkey is operated, D7,' 1'd6, 68,|', pcisma Both :magnets- SHM and STM are'thus energized simultaneously :and release the number wheels.

Premature release sion of impulses has been completed.

When relay B is-released, the locking circuits for all relays are opened and the switches are reset; r

Terminals l to 22 on arc ss'mc are connected to ground via 836 and 126 so that relay Rs energizes and causes the switch to rotate under the control of its own interrupter until the home position is'reached. Relay Rs is then released.

Assoon as switch SS has returned to normal the resetting circuit for S is completed over brush and arc ssma, brush and arc sma, ss3, b2, rdt, interrupter and Winding of SM to battery. This circuit is opened by sma when the switch S arrives in the home position.

What is claimed is:

1. In a key-controlled electrical character storage and transmission equipment, a plurality of groups of condensers, means for storing characters on said groups of condensers, an electromagnetic contact making marker device, means for transferring the stored characters in turn from said condenser groups to said marker device, prefix keys characterizing exchange areas, an impulse counting wiper, means for generating impulses,contacts for said wiper, means to norof condensers for storing different characters,

condenser charging means for giving all condensers of a group a preliminary charge of one polarity, means for subsequently charging one or more of the condensers of the group to opposite polarity to store a character, and condensercharge detecting means unresponsive on connection to a condenser containingsaid preliminary charge and responsive on connection to a condenser having a charge of opposite polarity.

3. In an electrical character storage and transmission equipment, groups of condensers for storing difierent characters, condenser charging means for giving all condensers of a group a preliminary charge of one polarity, means for subsequently charging one or more of the condensers of the group to opposite polarity to store a'character, an electromagnetic contact making marker device, means for transferring the stored characters in turn from said condenser groups to said marker device, impulse generating means, and means under the control of'said marker device to control the value of impulses sent out by said impulse generating means.

4. In a. key-controlled electrical character stor-.

age and transmission equipment, a plurality of groups of condensers, means for storing characters on said groups of condensers, an electromagnetic contact making marker device consisting of a group of relays equal in number to the condensers in a group, means for transferring the stored characters in turn from said condenser groups to said marker device, means for generating impulses, an impulse counting wiper, contacts for said wiper, means under the control of said marker device to mark said contacts, and means under the control of said wiper to control the number of said impulses transmitted, said wiper also effective over other contacts to control the transfer of said stored characters asserts from saidcondenser groups to said relay group.

restore said marker device and to reset said marker device in accordance with the condition of a condenser group.

6. In a key-controlled electrical character storage and transmission equipment, a plurality of groups of condensers, a group. of relays equal in number to the condensers in a group, an impulse counting wiper, means for storing a first character on said relays, means for storing a plurality of other characters on said groups of condensers, means for generating impulses, means under the control of said wiper during successive rotations to control the value of said impulses in accordance with the setting of. said relays, to restore said relaysand to reset said relays in accordance with the condition of a condenser group, a test relay, a normal contact for said wiper, means for operating said test relay over said normal contact. and back contacts of all relays of said relay group, and means under the control of said test relay'to release said storage and transmission equipment.

7 In a key-controlled electrical impulse sender equipment, individual digit keys, prefix keys characterizing exchange areas, separate digit storing means operated by said individual keys and by one of said prefix keys, and digit trans- "mitting means controlled by either storage means to send out the same plurality of digital impulse combinations.

8. In a key-controlled electrical impulse sender equipment, individual digit keys, prefix keys characterizing exchange areas, storage means for a plurality of individual digits, separate storage means operated by said pref x keys for storing digit combinations characterizing said exchange areas, means responsive to the operation of individual digit keys for distributing successive digits to corresponding individual storage means, and means under the control of a prefix key to cause said distributing means to skip a plurality of individual storage means to prepare other storage means to respond to subsequently operated individual digit keys.

9. In an electrical character storage and trans- WILLYPOULIART.

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