US2467310A - Antikickoff device for telegraph repeaters - Google Patents

Description

Aprll 12, 1949. R. B. HEARN ET Al. 2,467,310

ANTIKICKOFF DEVICE FOR TELEGRAPH REPEATERS original. Filed July 1, 1944 2 sheets-sheet 1 April 12, 1949. R. B. HEARN ET Al.

ANTIKICKOFF DEVICE. FOR TELEGRAPH REPEATERS 2 Sheets-Sheet 2 Original Filed July l, 1944 NVENTORS c. sun/FF ATTORNEY atented pr. 12A, 194g UNITED STATES PATENT OFFICE AN TIKICKOFF DEVICE FOR TELEGRP REPEATERS` original application J'uiy i, 1944,- serial No.

543,112. Divided and this application July 31- 1946, Serial No. 687,430

2 Claims. l

This invention is a division of that disclosed in our application, Serial No. 543,112, filed July 1, 1944, for Telegraph repeater system, now Patent No. 2,422,677. This invention relates to telegraph systems and particularly to an improved direct current intermediate telegraph repeater capable of receiving from one telegraph line section and retransmitting to another line section.

An object of this invention is the improvement of telegraph repeaters. A more specific object of this invention is the improvement of intermediate telegraph repeaters so as to insure satisfactory operation on lines of very long span.

Another more specific object of the invention is the provision of a type B polarential repeater for use at an intermediate lpoint in a telegraph line of long span, said repeater being arranged to receive polar signals from either of two very long line sections connected to the repeater and to serve as the differential sending end of a type B polarential repeater in 'repeating the signals to the other very long line section, said repeater including means for preventing kick off of the receiving relay due to the heavy surges from the very long line section.

The improvements herein are shown applied to what is known in the art as a type B polarential telegraph repeater system. Such a system is disclosed in the patent to W. W. Cramer, 2,131,870, October 4, 1938. The principles of operation of the type B polarential repeater system to which the invention herein is applied will be described sufficiently so that the manner in which the invention herein cooperates. with such a system may be better understood.

The improved intermediate repeater herein provides half-duplex operation only. The repeater includes monitoring facilities which are the subject of claims in the application, Serial No. 548,112, mentioned in the foregoing.

The repeater herein is designed for operation on simplexed field wire line circuits, composited or simplexed open wire and simpleXed -cable facilities with ground return.

The repeater herein contains a builtin rectier power unit. It is contemplated that teletypewriter transmitter and receiver lwill ordinarily be used with the monitoring facilities. A manual telegraph set integral with the repeater equipment is furnished for use when teletypewriter equipment eis not available for service.

The type B polarential intermediate repeater of the present invention receives polar signals from either line section and transmits diierential ,signals to the opposite line section.

The monitoring circuit in the local side of the repeater is arranged for operation with a sending and receiving teletypewriter or a manual telegraph set.

A lfeature of the invention is an improved antikick off feature for use in an intermediate repeater arranged for operation on lines of exceedingly high electrostatic capacity.

A further feature of this invention is an antikick oir circuit for a receiving relay in an intermediate repeater, which kick `oi circuit comprises a pair of auxiliary windings on the relay and a condenser charging and discharging circuit connected to the auxiliary windings and the line through two unidirectional current controls.

The operation of a -system embodying these and other features will become apparent from the following description when read with reference to the associated drawings herein, in which:

Fig. 1 shows the improved intermediate repeater of the invention;

Fig. 2 is a circuit used in explaining the principles of operation of a type B ipolarential telegraph circuit `with which the improved intermediate repeater herein is designed to cooperate; and

Figs. 3 and 4 are diagrams used in explaining the advantages of the type B polarential system per Fig. 2.

General Before proceeding with a detailed description of the invention herein, the invention will rst be described .in a general Way so that the detailed operation may be better understood.

It is to be understood that the invention herein is shown as applied to an intermediate repeater designed to function in a type B` polarential telegraph system. lTheline side of the intermediate telegraph repeater herein is designed for type B polarential operation (polar sending). Telegraph repeaters using the type B polarential method of transmission do. not require service adjustments to compensate for variations in the electrical characteristics of the line due to changes in the leakage resistance and the capacitance to ground as a result of changing weather conditions.

Polarentz'al operation Fundamentally a circuit operating on a polarential basis employs polar transmission in one direction and differential transmission in the other direction. These two terms have been combined to form the term polarential, In a polar transmission system the marking and spacing line currents are of the same magnitude and ow in opposite directions, and hence the receiving relay operates on the current reversals and requires no local bias circuit. In the differential direction of transmission of the polarential system the marking and spacing line currents flow in the same direction but are different in magnitude, the spacing current being about two and one-half times the marking current. A local biasing current is required at the differential receiving terminal which is xed at half the sum of the marking and spacing line currents. The relay biasing winding is poled in such a manner as to hold the armature to its marking contact. Since the biasing current is'greater Ythan the marking line current the armature is held to its marking contact during a marking line signal. Since the spacing line current is greater than the biasing current the armature moves to the spacing contact during a spacing line signal. Thus the net operating eiect on the relay is equivalent to polar transmission. To attain this equivalent in both directions of transmission the opposite ends of a polarential circuit are made dissimilar. One end of the circuit applies a negative and positive polarity of the same value to l the line during transmission. rihis end is known as the polar sending or differential receiving end. The other end of the circuit applies ground and positive polarity to the line during transmission. This is known as the differential sending or polar receiving end.

Refer now to Fig. 2 which shows two telegraph terminals connected through an intermediate repeater in a type B polarential telegraph system.

Intermediate repeater receiving from terminal A or terminal B In Fig. 2 the repeaters at terminal A and terminal B are arranged for polar sending, and the intermediate repeater is arranged for polar receiving with respect to both terminal A and terminal B.

All of the relays shown in Fig. 2 are polar relays. They are shown With their armatures in their marking positions in which positions they will be maintained while the system is idle or While the relay is receiving a marking signal during communication. The armatures of the re: ceiving relays 206 and 201 when they are in engagement with their marking contacts are connected to ground. The armatures of the receiving relay 203 at terminal repeater A and of relay 2l2 at terminal repeater B are maintained in' engagement with their respective marking contacts due to the effect of current in their biasing windings which is tending to actuate the armature of each towards its respective marking contact and which eiect preponderates over the lesser effect in the line winding of each of these relays which is tending to actuate the armature of each towards its spacing Icontact. More speciiically, to assume values for a typical case, a current of 36 milliamperes flows through the lower or biasing winding of relay i203 and of relay 2l2 tending to actuate the armature of relay 203 and of relay 2|? towards its marking contact. A current of 18 milliamperes flo-Ws through the upper or line winding of each of these relays tending to actuate the armatures of each towards its spacing contact.

Armature of sending relay 200 is under control of winding 20| which actuates the armature of relay 200 between its marking and spacing contacts when signals are originated at distant terminal A. When the armature of relay 200 is changed correspondingly, but the magnitude of actuated to the left to engage its marking contact 202, a circuit may be traced from ground through negative battery, contact 202, top winding of relay 203 to the line 20d which interconnects terminal repeater A with the intermediate repeater 205. The line rtends through the winding of receiving relay 2% in the intermediate repeater through the armature of relay 207 and marking contact 2&8 to ground. When the armature of relay 200 is actuated to engage its spacing contact 200 positive battery instead of negative battery is connected to the path just traced. The magnitudes of the voltages of the positive and negative batteries connected to the marking and spacing contacts of relay 1200 are equal. It will be assumed that each has a potential of 571/2 volts.

There is no biasing winding associated with the relays in the intermediate repeater. In response to the connection of negative 571/2-volt battery to the marking contact 292 of relay 200, the armature cf relay 205 engages its marking contact 2li). In response to positive M1A2-volt battery connected to spacing contact 209 the armature ci' relay 200 engages its spacing contact 2H. While terminal repeater A is transmitting to the intermediate repeater, the armature of relay 201 is maintained in engagement with its marking contact 203, so that ground remains connected to the receiving end of the line from terminal repeater A during transmission from terminal repeater A toward the intermediate repeater. The armature of receiving relay 20@ follows the reversals of the armature of relay 200. While negative 571/2-volt battery is connected to line 20d at terminal repeater A the effect of the current in the top winding of relay 203 tends to actuate the armature of relay 203 towards its spacing contact, but as mentioned above the effect of the current in the biasing winding of relay 203 is dominant and the armature of relay 203 is maintained in engagement with its marking Contact. When the armature of relay 200 is actuated to engage its spacing contact 20g the effect of the current in the upper or line winding of relay 203 is reversed so that it then tends to actuate the armature of relay 203 to engage its marking contact, augmenting the effect of the current in the lower or biasing winding. As a result of this the armature of relay 203 is maintained in engagement with its marking contact during transmission from terminal repeater A toward the intermediate repeater.

Since ground remains connected to marking contact 208, while the polarity of batteries of equal potential at terminal repeater A is reversed in transmitting from terminal repeater A toward the intermediate repeater, the armature of receiving relay 200 will be affected by equal and opposite forces for the marking and spacing conditions. As a result of this the armature of receiving relay 200 will respond with the same rate of Speed for each signal transition and relay 20E will repeat the signals received from repeater A toward the distant terminal repeater B without diierence in the duration of marking and spacing signal elements or without bias as this difference is called.

Ii the impedance of line A changes due to changed Weather conditions, etc., the magnitude of the current received by relay 205 will be the marking and spacing signals willv remain equal and thus the operation of relay 206 will not be adversely affected by such change.

The distant terminal repeater B is connected to the intermediate repeater 205 in the same manner as is the distant terminal repeater A and the operation of the circuit when repeater B transmits toward the intermediate repeater is the same as described for the condition wherein repeater A transmits towards the intermediate repeater.

Reference to Fig. 3 shows the effect of weather conditions upon the marking and spacing signals received at the intermediate repeater. When the weather is dry the marking and spacing signal current is 18 milliamperes. When the Weather is wet the received currents may be of any value less than 18 milliamperes, but they will be equal for each condition. Under the condition indicated in Fig. 3, it is assumed that milliamperes is being received for each signal for a particular wet condition.

Intermediate repeater sending to terminal A or terminal B The manner in which the intermediate repeater retransmits signals received from one terminal repeater toward the other terminal repeater will now be described. It will be assumed that terminal repeater A is transmitting toward the intermediate repeater and it will be explained how the intermediate repeater retransmits the signals received from repeater A to terminal repeater B and how terminal repeater B responds to the received signals.

In response to signals received from terminal repeater A the armature of receiving relay 206 in the intermediate repeater is actuated between its opposed contacts 210 and 211. For the marking condition the armature of relay 20E in the intermediate repeater engages its marking contact 210. The armature of sending relay 213 at the distant terminal repeater B will be maintained in engagement with its marking contact 214 under the influence of the current iowing in its winding 215. A circuit may then be traced from ground through marking contact 210 of relay 206 and the winding of relay 20'1 to line 216 which extends from the station at which the intermediate repeater is located to the station where the distant terminal repeater B is located.

The circuit continues through the top or line winding of receiving relay 212 at the distant terminal repeater B and through the armature and marking contact 214 of relay 213 to negative 571/2-vo1t battery and thence to ground. When the armature of relay 201i engages its spacing contact 2 I 1, positive 1l5-volt battery is connected to the circuit just traced.

If it is assumed that the direction of the new of the current is from the point of higher positive potential toward the point of negative potential, when the armature of relay 205 is in engagement with its marking contact 210, the direction of the flow of current is from the intermediate repeater toward the distant terminal repeater B. When the armature of relay 206 engages its spacing contact 211, the positive 115- volt battery connected to contact 211 is in a series aiding relationship with the negative 571/2- volt battery connected to the marking contact of relay 213 at terminal repeater B. The direction of the ilow of current will therefore, remain unchanged although its magnitude is increased. The armature of relay 201 will be maintained in engagement with its marking" contact 209- by the elect of each of these currents, each of Which tends to actuate the armature towards its marking contact 208. In the case of receiving relay 212 at the distant terminal repeater B for the marking condition the effect of the current in the upper or line winding of relay 212 is tending tc actuatethe armature of relay 21'2 towards its spacing contact. However, the effect of the current in the lower or biasing winding of relay 212 is dominant for this condition and the armature is maintained in engagement with its marking contact. For the spacing condition, however, when the voltage applied to the line is increased and the direction of the current in the line winding of relay 212 is the same as for the marking condition, its effect tending to actuate the armature of relay 212 towards its spacing contact is increased and the effect in the upper or line winding becomes dominant so that the armature of' relay 212 is actuated to engage its spacing; contact.

The total voltage applied to the line 215 during the marking interval is 571/2 volts and during the spacing interval is 1721/2 volts, which is threetimes the voltage applied to the line during thel marking interval. Therefore, the spacing line current is three times the marking line current when the intermediate repeater is sending. For a dry line condition these currents are 18 milliamperes for marking and 54 milliamperes for spacing.

Refer now to Fig. 4. This ligure indicates how the signals received from the intermediate repeater at the terminal repeater are not biased as a result of changes in weather conditions. The current in the lower or biasing winding of the receiving relay such as 212 is supplied from a local battery at each terminal. For the constants which are assumed, its magnitude is fixed at 36 milliamperes which is half of the sum of the marking and spacing signal current. When the weather is wet the eiect is as though a resistance were connected between the line 216 and ground. Thus the magnitude of the spacing current ilowing through the top winding of relay 212 when the two batteries are in series will be decreased.

Assuming that the resistance of each repeater is equal, the voltage at the center of the line would be negative 28% volts during the marking interval and positive 28% volts during the spacing interval. Therefore, the current through the leakage path would be approximately the same magnitude for the marking or spacing condition if the leakage is lumped at the center or uniformly distributed over the line. Thus if the leakage current is about 4 milliamperes, the marking current in the upper winding of relay 212 is increased by that amount and the spacing current is decreased an equal amount. Under such a condition the magnitude of the spacing current will be 50 milliamperes and the magntude of the marking current will be 22 milliamperes. The sum of these two currents is still 72 milliamperes as before and the magnitude of the biasing current of course remains 36 milliamperes. The difference therefore between the magnitude of the biasing current and the magnitude of the spacing current remains the same as the difference between the magnitude of the biasing current and the magnitude of the marking current and the receiving relay 212 responds without bias to the signal elements re gardless of changing weather conditions.

f aref-,fais

y AIntransmitting from the intermediate repeater 205 towards terminal repeater A the operation is the same as describedfor transmission from intermediate repeater 205 towards terminal repeater B.

The invention herein is an improved intermediate repeater of the type shown in Fig. 2. The repeater per Fig. 2 has been improved in accordance with the present invention by the addition of an anti-kick off circuit which permits the intermediate repeater of the invention herein to, function with line sections having very long 'spans and subject to very heavy current surges due to very high electrostatic capacity without preventing its use on linesections of short span or'normal span and having low or normal capacity. The repeater to which the anti-kick oif feature of the present invention has been added differs also from presently known type B polarential repeaters in that it includes also a local monitoring circuit and a special power supply circuit.

Improved intermediate repeater Refer now to Fig. 1. In this gure an intermediate repeater is shown in which the basic transmission features are the same as described for intermediate repeater 205 per Fig. 2 but the repeater is equipped with a special monitoring circuit, an improved anti-kick off circuit and an improved power supply circuit.

In Fig. 1, lines and |02 correspond to lines 204 and 2 l0, respectively, in Fig. 2 and extendto distant terminal repeaters corresponding to distant'terminal repeaters 'A and B, respectively, in Fig. 2. Relay |03 corresponds to relay 20s and relay lllll'corresponds to relay 201 in Fig. 2. Two newrelays, sending relay |05 and receiving relay |06,both of'which function in the improved monitoring circuit, have been added to the intermediate repeater. In the case of relays 205 and 201 in Fig. 2 there was but a single winding, namely, the line winding, on each of therelays. Relays |03 and |04 each have two additional windings. In addition to the top or line winding oneach of these relays the two lower windings of each are connected in an improved antikick off circuit comprising the two windings, two resistances, such as |01 and two rectier umts such as |08 and |09, a condenser, such as H0,- and the inductance coil 90 all of which are assciated with the anti-kick ol circuit of relay |03;

The intermediate repeater per Fig. 1 may be arranged so that the monitoring facilities are in effect disconnected. Such is the condition when no apparatus is connected to any ot the three jacks' l1, i8 and l lil, shown at the lower right of the figure. The monitoring circuit is arranged to function either with teletypewriter facilities, such as the receiving teletyp'ewriter apparatus, indicated by the receiving magnet |20, and the teletypewriter transmitting apparatus, indicated by the transmitting contacts |2|, orwith a manual telegraph transmitting key and a telephone headset receiver such as |22 and |23, respectively. All of this apparatus is well known in the art. When no apparatus is connectedto jacks H1, H8 and H0, which is the condition shown in the drawing, the circuit per Fig. 1 is arranged to function as an intermediate repeater without monitoring facilities.

lAsstated above, the circuit per Fig. l is arranged to function with various power supply' arrangements. 'For the present it will be assumed 8 that the circuit -is to function withl a-'115-'vclt direct current supply in which case the vpower circuit included in rectanglev |25 perfcrms no function. Key |265 vis actuated so as to engage its upper contacts. The negative-terminal of the 1l5-volt direct current supply is ccnnected to ground |25 throughcontacts |21 and |23-of key |2d to the negative terminal of the ll-volt ydirect current supply. From the positive terminal of the -volt direct current supply a circuit may be traced through fuse |29, contact 130,-ccntact I3! and fuse |32 to bus-bar |33 from which point parallel branches extend. One branch extends through resistance 35|' to spacing contact |35 of relay |03A and spacing contact |30 of relay |534. A circuit may also be traced from ground |31 through lcontact |30 of key |22, contact |30 of jack H1' and through the inductance coil Mil 'of yfilter la! to marking contact -IZ of relay les and .marking contact |23 of relay lllf; From this it may be seen that the battery conditions connected to the marking and spacing contacts oi relays It and llll are the same as for the corresponding relays inintermediate repeater 205 in Fig. 2.

It was explained above that the distant end of the line lil in Fig. 2 which corresponds to line lGl in Fig. l is connectedto'negative 571/2- volt battery for the marking'conditicn. A circuit mayA be traced in the intermediate repeater per Fig. l throughinductance IM of filter liti, inductance lfi, top or linewinding of relay |03, contact |151 of the -B-cut line key and'through the armature of relay liili which is in engagement with its marking contact H33 from which point the circuit'has been traced-to ground. On the opposite side of the'repeater line |02 which corresponds to line El@ in Fig. 2 is terminated at the distant terminal'repeater B in negative 571/2-volt battery. The circuit may be traced in the intermediate repeater per Fig. 1 through inductance lele of filter M2, inductance Hill, top or line winding of relay |04, contact I5| ofthe A cut line key and the armature of relay |93 which is in engagementwith its marking contact it? from which point the circuit has been traced to ground |31. The effect-'of the anti-kick off circuits will be described hereinafter. Disregarding this effect, which tends to counteract heavy line current surges, relays |03` and lii'will operate in the same manner as described above for relays 2015 and 201 in the intermediatev repeater 2ll5 per Fig. 2.

Monitoring circuit The manner in which the monitoring circuit functions will now be described. It will be `assumed that the teletypewriter monitoring facilities are to be employed. vThe teletypewriter transmitter and receiver are each equipped with a cord and a plug so that they may be connected to and disconnected from jacks in the monitoring circuit. When the teletypewriter transmitter and receiver are to be used for monitoring, plugV |52 is connected to jack lli-'4 to interconnectthe teletypewriter transmitter |2i and the monitoring circuit and plug |53 is connected to jack Hl to interconnect the typewriter receiver. |20 and the monitoring circuit. 'When plug |53 is inserted in jack lll, contact |30 is opened and contact |`l| is closed. This transfers the path supplying ground |31 to the intermediate repeater to a path that extends through the arma-.-

ture of relay |515 and its markingcontact Vitto ground |115.J A circuit may now be'trac'ed from the positive bus-bar |54 through resistance |55, bottom winding of relay |05, inductance |55 of filter |51, tip of jack H0, tip of plug teletypewriter transmitting contacts |50, ring of plug |52, and the ring of jack ||8 to ground |553. A circuit may also be traced from the positive bus-bar |54 through resistance |00, top winding of relay |05, contact |6| of jack |50, bottom Winding of relay |00, and contact of jack I8 to ground. The iirst of the above two extended through the bottom winding oi relay |05 and the second extended through the top Winding of relay |05. The eifect of the current flowing through the bottom winding oi relay |05 tends to actuate an armature oi rela-y to engage with its right-hand or markingr contact and when teletypewriter contacts l2`| are closed this effect is dominant over the effect of current flowing in the top winding of relay |55 which tends to actuate the armature of relay |05 toward the left to engage with its spacing contact. When the teletypewriter transmitting contacts 12| are open, the circuit through the bottom winding of relay |05 is deenergized and the armature of relay |05 is actuated to cose its spacing contact under the influence of the current in its upper winding. The effect of the current flowing through the bottom winding of relay |05 tends to actuate the armature of relay to engage with its right-hand or marking contact.

From junction point |54 in the path extend ing toward the distant repeater A, a branch extends through resistance |50, top winding of relay |00, resistance |51 and contact to ground. From junction point |65 in the path extending toward the distant repeater B, a branch extends through resistance |08, middle winding of relay |05, resistance |52 and Contact to ground. When the distant terminal repeaters are terminated in negative battery for the marking condition, there is no current flowing in each of the two upper windings of relay since the paths from junction points |00 and |55 through each of the two upper windings oi relay |06 are shunted by a path to ground which been traced in the main repeater circuit. For the marking condition therefore the current in the lower winding of relay is holding the amature of relay |55 on its marking contact.

It will be assumed that the armature oi the sending relay in distant terminal repeater A impresses positive battery on line |0| to transmit a spacing signal toward the intermediate repeater. As explained above, the voltages impressed on line 50| at the distant terminal are equal in magnitude and of opposite polarity for the marking and spacing conditions. The elect of the current of reversed polarity in the top winding of relay |03 operates the armature of relay |03 to its spacing contact. Operation of relay |03 to its spacing contact removes ground and applies positive ll5-volt battery to junction point |65. This causes a current to flow in the middle winding of relay |00 which is poled in such a manner and is of suflicient magnitude to overcome the effect of the current owing in its lower winding thus operating the armature to spacing contact |10. When the armature of relay |03 is again actuated to engage its marking Contact |52, the conditions prevailing originally in all three windings of relay |05 will be reestablished and its armature will again engage its marking contact.

As the armature of relay |05 follows the received signals, ground connected to the armature is alternately connected to and disconnected from the circuit extending through the winding of the receiving magnet |20. This circuit may be traced for the marking condition from positive battery at bus-bar |54 through resistance |15, inductance |15 of lter l'l'l, tip of jack ||1, tip of plug |55, winding of the teletypewriter receiving magnet |20, sleeve of plug |53, sleeve of jack ||1, inductance |13 of filter |11 and the marking contact |59 of receiving relay |06 to ground energizing magnet |20. When marking contact |50 is opened, the receiving magnet |20 is deenergized.

The manner in which signals are transmitted from the teletypewriter transmitter |2| will now be described. It was explained above that as the teletypewriter contacts |2| were opened and closed, the armature of relay |05 was actuated so as to follow the signals. When the armature of relay |05 is in engagement with its marking contact |12, ground l'll is connected through contact |12 to marking contacts |42 and |43 of relays |03 and |04, respectively. The path has heretofore been traced. When teletypewriter |2| is transmitting, the armatures of relays |03 and |04; remain in engagement with their respective marking contacts. Thus, ground for the marking condition is impressed on lines |02 and |0| simultaneously. When a spacing signal is transmitted from sending relay |05, Ithe armature of relay |05 is actuated to engage its spacing contact |13. Spacing contact |13 is connected to the l15-volt positive battery bus-bar |54 through resistance |34. Positive l15-volt battery is thus impressed through marking contacts |42 and |43 of relays |03 and |04 on lines |02 and I0| to transmit a spacing signal to the distant terminal repeaters A and B simultaneously.

Cutting feature The intermediate Irepeater herein includes a cutting feature to facilitate the location of trouble and to permit limited communication while trouble conditions prevail. It will be assumed that plugs |52 and |53 remain inserted in jacks H8 and ||1, respectively. When the circuit to distant terminal repeater A appears to be in trouble, cut line A key may be operated to its alternate position in order to establish communication with distant terminal repeater B. Operation of cut line key disconnects the line winding of relay |00 from the armature of relay |03, through the opening of contact |5| and connects it directly through contact |10, conductors i8! and |82, to the armature of relay |05. In response to the operation of transmitter |2| ground for marking and -volt positive battery for spacing will be connected through the contacts of relay |05, contact |1|, inductance |40 of filter |4|, conductors |82 and |8|, contact |19 and the top winding of relay |04 to line |02. Simultaneously, the same signals will also be impressed on line |0| through the normal path for transmission from the monitoring circuit which has been traced through the marking contact of relay |04. If the circuit to distant terminal repeater B cannot loe established and communication to distant terminal A is satisfactory cut line B key may be operated to open contacts |41 and close contacts |80. This disconnects the armature of relay |04 in a manner similarto that just described for cut key A. Signals may then be impressed on line l0! from the contacts of relay |05 through contact |1|, inductance |40 of lter 4|, conductors |82 and |83, contacts |80 and through the top winding of relay |03 to line itl. Simultaneously, the .signals `will continue to-be'transmitted to line |02 through marking Contact Mii? of relay 03. As soon as the circuit is ieest'ablished both circuits will immediately re ceive signals from the! intermediate repeater. Furthermore, even though contact |10 is closed and contact iill is open, signals incoming over line |02 will be repeated through relay ltr?. to line '|0|. Correspondingly, when contact i8@ is closed and Contact |19 is open si-gnals incoming from line will be repeated to line |02.

Attention is called to the fact that when signals are transmitted from the teletypewriter transmittel' |2|, operating relay |05, two transmitting paths are established Afor each of the above-describedconditions, each of which paths in extending irom the armature of -relay to lines |0| and |02 passes through junction points |64 and |65 in each instance. For the marking condition junction points |00 and |55 are connected simultaneously through contact |12 to ground. For vthe spacing condition junction points li and |65 are connected simultaneously through contact |13 to positive 115-Volt battery. Relay |06 will, therefore, follow the signals from teletypewriter transmitter |2| and impress the sig-- nals on vthe teletypewriter receiver magnet |20 to providea home copy of the message transmitted from the Ytelety'fpewriter transmitter |2| in the monitoring circuit.

lManual telegraphset circuit operation When themonitoring circuit is to be arranged formanual operation instead of teletypewriter operation, the t'eletypewriter receiver |20 and teletypewriter transmitter 4are not connected through their associated plugs and jacks to the monitoring circuit. Contacts IBI, It and |1| are open and contact l'llis closed. The headset receiver |23 vis connected through plug |85 to jack H9. `'Contacts |86, |81 and |88 are closed.

Theopening of contact |63 and the closing oi Contact '|81 transfer the ground termination of thethree right-hand terminals of the three windings of relay '|00 from the former to the latter Contact. The opening of contacts |0l deenergizes thetop or biasing winding of relay |05. The disconnection of vplug |52 from .jack opens the path through the lower or operate winding of relay |05. `-Relay |05 plays no part in manual operation of the monitoring circuit. The lefthand terminal of the bottom winding of relay |06 is connected through closed contact |86 of jack 9 to resistance |60, thence to bus-bar |50 which connects to .positive 115-Vo1t battery. The reclosing of contact |30 reconnects' marking contacts |2532 and |43 of relays |03 and |04 ltoground |31 'for the marking condition. When .manual telegraph key '|22 is depressed, ground |31 is dis-- connected 'from its marking contactsI and vpositive battery from :bus-bar .|54 is connected through resistance |35, conductor |03, -inductance 19d of filter Ml, and-contact I06i-of key |22,\rom which point the circuit hasbeen traced through marking contacts AH32 and .|43 of :relays |03 and |04 to lines '|02 and |0| respectively. Thus ground for markingandjll volts .forspacingrarefalternately lconnected to 'lines .|02 and |.0I simultaneously through thefoperation of .key |22.

Relay '|06 will respond to signals vtransmitted from key |22. .Its voperation .for .manual operation'oi key |22 Vis the same .as for the operation of teletypewriter transmitter |2| `.except that changes ofupotential'of points |64 and |65 with 12 respect to ground through the two topwndings of relay 05 are controlled by key |22 rather than by reiay |05.

Relay |00 will respond to signals incoming from line i0! or line |02. The operation of relay |06 `lor either the transmitting or receiving condition while the monitoring circuit is arranged for imanual operation will cause a tone to be generated in an oscillating circuit when the armature of relay lil engages its spacing contact. The tone may be heard in the receiver |23. The oscillating circuit comprises the' neon lamp |09, resistance i, adjustable potentiometer |02, condense-r |00 and the receiver |123. The circuit may be traced from positive volts at bus-bar |50, through resistance |85, variable potentiometer |92 and Contact |30 of jack l l1 to parallel branches. One branch extends through condenser |00, tip oi jack ||1, tip of plug |85, receiver |23, sleeve of plug |85, and the sleeve of jack HS to ground. The other branch extends through the neon lamp |89 to spacing Contact |10. When the spacing contact is closed the branch is terminated in ground. Potentiometer |92 may be adjusted to provide a `vvicle range of frequencies within the audible range. In the id-le or marking condition the neon lamp |89 does not function since relay |05 is held to its marking contact by the biasing current in its lower winding. When battery is applied to both the upper windings of relay |05 by operation of the key |22 or to one winding by the operation of relay |03 or |00, contact |10 of relay Hl closes and a tone is heard in the receiver.

Anti|cick oyf feature The intermediate repeater of the invention herein is arranged to insure against false operation of reiays |03 and iet clue to current surges of very high magnitude caused by exceeding high capacity between the lines itil or |02 and ground.

Previously in the art, when operating over lines having appreciable capacity, it was customary to provide a balancing network with constants approximating the constants oi the line so that surge currents were applied through a balancing Winding on the relay to balance out the eiect of surge currents through the operating winding. The present circuit uses an arrangement whereby a heavy charge is stored in a condenser to hold therelay armature on its marking contact during the interval while a heavy surge through the operating winding is tending to kick the armature toward the spacing Contact. This permits the operation or" this repeater on lines having a wide range of capacity without the necessity for making .adjustments to compensate for the capacity.

The manner in which the improved anti-kick oli `feature of the invention herein functions' will now be explained for the case of relay |03.

It will be assumed that the current and voltage conditions have become stabilized for the marking condition. Negative battery is connected to the left-hand tenminal of the .top winding of relay |03 and ground is connected to its right-hand terminal. .The -eliect vof the current in the top winding of relay |03-tends to actuate the armature of relay |03 to the left to engageiits marking contact MZ. vWhen conditions are stabilized for the marking condition there is no currentlowing in the two `bottom windings of `relay |03. Attention is called to the fact thatthese two windings are connected in parallel and the effect foi each of the two anti-kick off windings.is1 the'sarhe'as the effector the other. -Junction'points |90 and |99 are each at ground potential as the armature of relay |04 is connected to ground. Both terminals of condenser l are substantially at ground potential.

When the armature of relay i engages its spacing contact the potential of junction points |98 and I 99 -becomes approximately 115 volts positive. Rectier |09 is poled so that it passes current from battery of positive polarity. The current charges condenser ilil. No current flows through the two anti-kick off windings for this condition as rectier |08 is poled so that it does not pass current due to positive potential applied between junction point E99 and ground. Current flowing through rectifier ldd to the condenser l i) could pass through rectifier but junction points |98 and |98 are at the same potential. During the spacing interval line lill becomes charged. The portion of line |05 adjacent the intermediate repeater per Fig. 1 will be heavily charged positively with respect to ground. W hen the armature of relay |04 is again actuated to engage its marking contact, line itl will be grounded. A heavy surge of current due to the discharge of the positively charged line will be conducted from the left-hand to the right--hand terminal through the top winding of relay HB3. Since positive potential when applied to the righthand terminal of the top winding of relay tends to actuate the armature of relay i025 to engage its marking contact, the effect o the posim tive potential applied to the left-hand terminal. of the top winding of relay i0@ will tend to actuate its armature falsely to its spacing contact for an interval until conditions become stabilized. The length of the interval `will depend on the rrnagni-A tude and duration oi the discharge surge.

The constants of the anti-kick oil circuit are so chosen that they produce an effect on relay |03 which preponderates over the eiect of the kick olf surge. When in effect marking ground is connected to junction points |95 and |99, condenser ||0 discharges. The discharge current cannot flow through rectifier |59 as it is so polled that it cannot pass current of positive polarity which will be applied from the left-hand terminal of condenser H0. Rectifier |08 is so poled that it passes current of positive polarity from the left-hand terminal of condenser H0. The terminals of the two bottom windings of relay |103 are so connected that the effect of the current flowing through rectier |08 from condenser H9 and the two bottom windings of relay l 93 in parallel tends to maintain the armature of relay |53 on its marking Contact, during the interval while the kick olf current surge persists. Resistance |01 and inductance 90 assist in controlling the rate of discharge of condenser H0 through the lower windings of relay |03.

The presence of rectier |08 in series with the lower windings of relay |03 materially lessens the shunting effect of the condenser 0 with its discharge circuit, on the windings of relay |03. Without the rectifier |118 this effect would have a very detrimental influence in that it would make relay |03 Very sluggish so that it would not follow the signals received from the line with the same degree of accuracy achieved through the use of rectier |08. This permits operation over lines having appreciably higher capacity than would otherwise be possible.

Power supply circuit Attention was called in the foregoing to the fact that the intermediate repeater per Fig. 1

was arranged to be supplied with power from a number of different sources. It has been assumed heretofore that the power was obtained directly from a -volt direct current source. For this condition rectiiier circuit |25 was not required and switch |24 was actuated upwardly. The power circuit |25 is arranged so that it can, for example, convert l15volt or ZBO-volt alternating current into 115nvolt direct current. Further, the power circuit is arranged so that it can convert current from a relatively low voltage direct current source into direct current of a higher voltage. For instance 12-volt direct current may be converted into 115Volt direct current to operate the repeater herein. Conductors |0 and l| may be connected to a 115-volt alterhating current or a 23d-volt alternating current, or to a 1l5-vo1t direct current supply. If the source is 115 volts direct current, switch |25, as mentioned above, is operated upwardly. Power rectier circuit 25 is not involved under this condition. Conductor i0, which is grounded through contacts |28 and |21 at |26, connects to conductor l2 which forms one of the power supply conductors for the teletypewriter transmitter and receiver. Conductor il extends through fuse |29 and contact ill of switch |24 to conductor i3 to form 'the other power supply conductor for the printer. l15-volt direct current is furnished as a power supply for the teletypewriter for this condition.

If conductors i0 and are connected to a ll-volt alternating current supply, switch |24 will be in the position shown. Plug |5 will be inserted in jack id. Switch 33 will be closed to engage its right-hand contacts '53, 54 and 55. Conductor I5 connects to conductor |2 which forms one of the two power supply conductors for the printer. Conductor also extends through contact GS, contact i9, contact 22, coil 25 of transformer 5|, the top switch blade of switch 34%, contact 55, fuse li, contact 35, middle blade oi' switch contact 42, contact 4|, lefthand switch blade of switch 33, contact 35, Contact 2%, Contact Il, contact 66, and fuse |29 to conductor il. Coil 25 of transformer 5| is connected in `parallel with coil 25 across contacts 2|] and 22 through the middle blade of switch 34 and contact 54. Conductors and i3 are joined in the following manner. From conductor il, through fuse |29, contact 5S, contact Il, Contact 20, contact 35, left-hand blade of switch 33, contact 4|, contact 42, middle blade of switch 33, Contact 35, fuse 1|, contact 53, bottom blade of switch 3d, Contact 2|, contact lli and contact 6l to conductor I3. ll5volt alternating current power is supplied to the teletypewriter for this condition. The voltage impressed through coils 25 and 25 in parallel induces a voltage in the secondary 'I4 of the transformer 5l. Various taps from the secondary of transformer 'I4 are brought out to contact points on switches IES and 5i). Switch 50 provides a. coarse voltage adjustment and switch 49 provides a line voltage adjustment. The voltage output from the switches is impressed across the input of the rectiiier bridge comprised of rectiers 6|, E2, 63 and Eil. The rectiiied output of the rectiiier bridge is impressed through contacts 59 and l0 between ground |26 and bus-bar |54. The constants of the rectier circuit are chosen so as to translate the 11S-volt alternating current supply into 11S-volt direct current voltage. Shunt condenser 48 and the series inductance filter out any valternating current in the-output of the rectifier bridge.

When conductors I and Il are connected to 230-volt alternatingI current, switch 24 is in the position shown. Plug i is inserted in jack l5. Switch 33 is operated to engage contacts 35, 36 and 3l. Switch 3G is operated to engage contacts 5S, 5i and 5B. This results in the connection of coils 25 and 2E in series through the two top blades of switch 3ft across contacts 20 and 22 across which the ZBO-volt alternating current is impressed over a circuit which should be obvious from the foregoing. Coils 23 and 2 of autotransforrner 52 are also bridged across the 23o-volt alternating current supply contacts 20 and 22. A tap from the mid-point of these coils supplies L-volt alternating current voltage to the teletypewriter for this condition, over a path through the bottom blade of switch 34 to contact 2i, from which point the circuit has been traced to lower conductor i3 of the printer power supply circuit. When coils 25 and 2li are connected in series across a 230-vo1t alternating current power supply the output between ground and bus-bar |54 is li-volt direct current voltage as formerly.

When a 12-volt direct current power supply is used the teletypewriter is not used and no power is supplied to conductors i2 and i3. The

' 12-volt direct current is translated into 115-volt direct current in the following manner. Switch |24 is in the position shown. Plug l5 is not connected to jack I6. Switch 34 stands open as shown. Switch 33 is actuated to eng-age contacts 38, 3S and d0. The 12-volt direct current supply is connected across contacts 59 and 60. A circuit may now be traced from contact 60, through fuse LM, contact 38, left-hand blade of switch 33, contact 4i, contact d2, middle blade of switch 33, Contact i0 and inductance coil 135 to junction point 'i5 where parallel branches are formed. One branch extends through contact 40, right-hand blade of switch 33, contact 43, winding 20 of vibrator 'it and contact 32 to contact 50. The second branch extends from junction point 'i5 to the mid-point of coils 21 and 26 of transformer 5l. When contact 30 is closed the 4circuit continues through coil 2i' and contact to contact 59. Coil 21 is energized. Winding 2S is energized actuating armature Ti to open contact 30 and close contact 3|. Coil 28 is energized and its eiect is in a direction the reverse from that of coil 21 when coil 27 was energized. When contact 32 opens magnet 29 is deenergized to reestablish the original circuit. The result is the impressing of an alternating voltage on the secondary 1li of transformer 5l which is translatedinto 115 volts direct current and applied between bus-bar |54 and ground.

subject to high capacity discharge effect tending to operate said relay falsely, a line winding on said relay connected to an anti-kick oir winding on said relay, a condenser connected to said line and to said anti-kick off winding, a rst rectiiier intermediate said line and said condenser, said rst rectier so poled as to permit the charging of said condenser through said rst rectier at a first time, when a first signaling condition prevails and said eifect does not prevail, a second rectifier, intermediate said condenser and said anti-kick off winding, said second rectier so poled as to permit the discharging of said condenser through said second rectier and through said anti-kick oi winding when a second signaling condition prevails and while said eiect prevails.

2. In a type B polarential telegraph repeater system, a telegraph line of very long span and of high electrostatic capacity, a polar signal receiving-dinerential signal sending repeater connected to said line, said repeater having an antikick oi circuit to condition said repeater for operation with said line, said circuit comprising a condenser having one terminal connected through a resistance to ground and a second terminal connected to the junction between two unidirectional current devices, the first of which devices is connected directly to a junction point between a line winding and an anti-kick off winding on a repeater relay, and the second of which devices is connected in a path extending through said anti-kick ofi winding to said junction point, said first device being so poled as to permit the charging of said condenser while a first signaling condition prevails in said repeater, said second device being so poled as to permit the discharging of said condenser through said anti-kick oft winding while a second signaling condition prevails in said repeater, to prevent kick-01T of an armature on said relay while said second signaling condition prevails.

RICHARD B. HEARN.

CARLETON B. SUTLIFF.

REFERENCES CITED The iollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,147,690 Cramer Feb. 21, 1939 2,216,820 Lewis Oct. 8, 1940

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