US2454089A

US2454089A - Regenerative repeater

Info

Publication number: US2454089A
Application number: US460948A
Authority: US
Inventors: Wilton T Rea; Jefferson R Wilkerson
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1942-10-06
Filing date: 1942-10-06
Publication date: 1948-11-16
Anticipated expiration: 1965-11-16
Also published as: GB670874A; FR963410A; CH268699A; NL74393C; BE480101A

Description

Nov. 16,1948. w, T, REA HAL 2,454,089

REGENERATiVE REPEATER Filed OCL. 6, 1942 2 Sheets-Sheet l 2/ F IG auraom/a L/NE "/NmM/Na LINE WIRE/4' INVENTORS W// KERSON ATTORN Y Nov. V16, 1948. w, T, REA E 2,454,089

REGENERATIVE REPEATER 2 Sheets-Sheet 2 FIG. 2 0UT60IN6 LINE Filed Oct. 6, 1942 POLARIZED INCOM/NG LINE.

57 WIRE/1 v WVENTORS' .5. ML KERSON ATTORNEY Patented Nov. 16, 1948 ra ses UNl'i'E STATES PATENT OFFICE.

26 Claims.

This invention relates to telegraph apparatus and systems and particularly to regenerative telegraph signal repeaters.

An object of the invention is to time the retransmission of telegraph impulses by electronic discharge tube means thus dispensing with mechanical distributors.

Another object of the invention is to time the interval allotted to the reception and transmission of a permutation code signal combination by a single electron discharge tube controlled by an impulse accumulating circuit.

Another object of the invention is to time the interval allotted to the reception and transmission of a permutation code signal combination by a' counting chain of electron discharge tubes.

Another object of the invention is to provide an impulse generator for actuating the impulse accumulating circuit for the electron discharge tube chain circuit.

The invention features a cold cathode electron discharge tube for initiating cycles of signal regeneration.

The invention also features electron discharge tubes in a commutating circuit controlled jointly by received signaling impulses and by the impulse generating means for controlling the retransmission of signaling impulses.

In accordance with one embodiment of the invention a signal receiving relay deactivates a normally operative electron discharge device which deactivation sets in operation an electron discharge tube oscillator. The oscillator is activated at full amplitude without transients and the successive cycles of alternating current thus generated are rectified to produce direct current impulses. These impulses seek to activate the deactivated one of two electron discharge devices, one or the other of which is always conductive, and the receiving relay, which is under the control of received signals, determines whether or not the then. deactivated electron discharge device shall be activated. Each of the electron discharge devices upon being so activated quenches the other, and a signal transmitting relay is controlled in accordance with the activation of the particular electron discharge device.

Impulses generated by the oscillator are rectified and impressed upon a condenser which controls the grid of an electron discharge tube and when the condenser has received impulses equal to the number of impulses contained in the signaling code upon which the system is operable, the condenser is charged sufficiently to render the associated grid controlled electron discharge tube assignors to Hell- Telcconductive. which reactivates the electron discharge tube initially deactivated by the receiving relay, which in turndeactivates the oscillator, thus restoring the system to normal condition.

In accordance with an alternative embodiment of the invention, a counting chain of electron discharge tubes is employed instead of the condenser charging and grid controlled tube timing circuit. One tube ofthe chain is normally conductive and upon the starting of the oscillator in response to operation of the signal receiving relay a tube in the chain which had been prepared for activation by the normally conductive tube is activated and in turn quenches the normally conductive tube. Each tube in the chain prepares the next tube to be activated andthe activation of the tube is caused by successive rectifled impulses from the oscillator. When the normally conductive tube in the chain is reached, that tube is reactivated under the control of a rectified impulse derived from the oscillator and that tube deactivates the oscillator.

For a complete understanding of the invention reference may be had to the following detailed description to be interpreted in the light of the accompanying drawings wherein:

Fig. 1 is a schematic circuit diagram showing that embodiment of the regenerative repeater which employs a condenser charging and grid controlled electron discharge tube timing system, and

Fig. 2 is a schematic circuit diagram showing the alternative embodiment of the regenerative repeater which employs a timing chain of electron discharge tubes.

Referring now to the drawings, and particularly to Fig. 1, the reference numeral ll designates a polarized receiving relay which has operating and biasing windings. The operating winding has one terminal connected to grounded battery I2 and the other terminal connected to receiving telegraph line 13. The biasing winding of relay H has one terminal connected to grounded battery :2 and the other terminal connected to ground. The operation of relay H is such that when line it is in the marking condition the armature of the relay engages the upper or marking contact which has been designated M and when line i3 is in spacing condition the armature engages the lower or spacing contact which has been designated S.

The marking and spacing contacts of relay H are connected through resistors I4 and I6, respectively, to the control anodes of cold cathode gasfilled electron discharge tubes l1 and I8, respec- "protective resistor 'flow of plate current in resistor tively. The cathode of tube I1 is connected to one terminal of the right-hand winding of a transmitting relay l 9, the other terminal of which is connected to ground and this winding, when energized, causes the armature of the relay to engage the upper or spacing contact which has been designated S. The cathode of discharge tube [8 is connected to one terminal of the left-hand winding of transmitting relay I 9 and this winding when energized operates the armature of the relay to the lower or marking contact which has been designated M. From this it will be apparent that tube l1 operates relay H! to drive its armature to spacing and tube I! may be designated as the spacing control tube whereas tube is when conductive drives the armature of relay I9 to marking and may be designated as the marking control tube. The marking and spacing contacts of relay I9 are connected to positive and negative batteries, respectively, and the armature of the relay is connected to transmitting line conductor 2|.

The main anodes of tubes I1 and I8 are connected through

individual resistors

22 and 23, respectively, and through common protective resistor 24 to the positive terminal of battery 26, the negative terminal of which is grounded. Also, a condenser 21 is connected directly between the main anodes of discharge tubes I1 and Ill. The manner in which tubes l1 and I8 control transmitting relay 19 will be described later.

The armature of receiving relay I I is connected by conductor 28 through dropping resistor 25 and 29 to the negative terminal of battery 3 l, the positive terminal of which is connected to ground. A conductor 32 extends from the marking contact of receiving relay II through resistor 33 to the cathode of a cold cathode gas-filled electron discharge tube 34. The main anode of discharge tube 34 is connected through conductors 31 and 38, left-hand inductance winding 39 and in parallel therewith through the series of

resistors

41 and 42, and finally through the right-hand inductance winding 43 to ground, which is at the same potential as the positive 'end of battery 3|. When the system is in the idle condition as shown with the armature of receiving relay H on the marking contact, electron current flows from the negative terminal of battery 3| over traced to the cathode of tube 34, through the discharge path to the anode of tube 34, and over the circuits just traced to ground on the righthand inductance winding 43 .and to the positive terminal of battery, 3|.

Resistor 42 is employed as a potentiometer and its movable contact is connected to the grid of the left-hand triode of a twin triode discharge tube 45. The cathode of the left-hand triode is connected through resistor 41 to the point of interconnection of

inductance windings

39 and 43. Thus a portion of the voltage appearing across the winding 39 of the inductance is applied to the rid of the left-hand triode of tube 46. The

41 applies a positive potential to the cathode of this triode. Due to the low resistance of the inductance coil, the flow of current in tube 34, passing through the inductance, causes only a small negative voltage to appear on the grid of the left-hand triode of tube 46. This is insufficient to cut off the flow of steady plate current.

Connected to conductor 3! and thus to the left-hand end of inductance winding 39 are the contact arms of four multiple contact switches the circuit previously 5|, 52, 53 and 54. The contact arms of switches 5i and 52 are ganged for concurrent operation and the contact arm switches 53 and 54 are ganged for concurrent operation. The contacts of switches 5|, 52, 53 and 54 are connected in various combinations to one side of capacitances in

groups

55, 56 and 5'! and the other side of each of the capacitances in the three groups is connected to ground. By the manipulation of switches 5| 52, 53 and 54 various combinations of capacitances may be connected in parallel between conductor 31 and ground to provide a single resultant capacitance value, and the condensers are so arranged with reference to switches 5|, 52, 53 and 54 that switches 53 and 54 provide coarse or relatively important changes in the resulting capacitance value and switches 5| .and 52 provide fine or minor changes in the resulting capacitance value. Since various combinations of parallelly connected condensers are connected between conductor 31 and ground under the control of the switches and since

inductance windings

39 and 43 are connected between conductor 37 and ground, the condensers are in parallel with the inductances, which establishes an oscillatory circuit. Furthermore, since the grid of the left-hand triode of tube 46 is connected to one end of this oscillatory circuit through resistor 4| and potentiometer 42 and since the cathode of the left-hand triode is connected to a point intermediate the ends of the inductive branch of the circuit through resistor 41, the system comprises an electron discharge tube oscillator which will generate oscillatory current, as long as tube 34 is non-conducting, at a frequency determined by the adjustment of switches 5i, 52, 53 and 54. These switches are in practice adjusted so that the frequency of oscillations generated is twice the signaling frequency and each cycle of oscillation is of the same duration as a normal signaling impulse of the code upon which the system is operable. The anode of the left-hand triode of tube 46 is connected through resistor 51 to the positive terminal of battery 58 the negative terminal of which is connected to ground. The positive terminal of battery 58 is also connected through potentiometer 59 and resistor 6| to the negative terminal of battery 62. the positive terminal of which is grounded. A potentiometer 63 is connected in parallel with potentiometer 59. The constants of the oscillator are so adjusted that the circuit performs undamped oscillations and the configuration of the circuit is such that the oscillations have no starting transients and, accordingly, the first and all succeeding cycles are developed at full amplitude. The operating characteristics of an oscillator of the type shown herein are fully disclosed in copending application Serial No. 432,823, filed February 28, 1942, now Patent No. 2,370,685, granted March 6, 1945, by W. T. Rea et al., and the disclosure of this copending application is incorporated herein by reference as part of the present specification.

The cathode voltage for the right-hand triode section of tube 46 is derived from the adjustable contact of potentiometer 59 and the plate voltage for this triode section is derived from the adjustable contact of potentiometer 83. The anode circuit of the right-hand triode of tube 46 includes the primary winding of a transformer 66 which is shunted by a resistor 61. The voltage with reference to ground which appears at the left-hand end of inductance winding 39 is connected through

conductors

38 and 68, and resistor 69 to 6 the grid of the right-hand triode of tube 46. Thus firing potntial of the control gap of the tube the grid of the right-hand triode of tube 45 is and may, for example-be oi the order oi fifty controlled in accordance with the potentials devolts. ()ne or the other of the tubes l1 and I8 veloped across the oscillatory circuit and the plate must be conducting, as will be described later, circuit of the rightehand triode becomes conduc- 5 and since the armature of relay H is shown in entive whenever the voltage applied to the grid begagement with the marking contact for the idle comes more positive than that of the cathode and condition of the apparatus it will be assumed that becomes non-conducting whenever the voltage tube l8 which controls the transmission of markapplied to the grid becomes more negative than ing impulses is conducting. It is to be noted that the cathode. Each time the anode circuit of the 10 the control anode of this tube is connected to right-hand triode passes from the conductive to the spacing contact of receiving relay II and the the non-conductive condition a positive impulse is reason for this arrangement will appear later.

applied to the secondary of transformer 66. The Upon the movement of the armature of

relay potentiometers

59 and 63 from which the cathode I! into engagement with the spacing contact in and. anode potentials for the right-hand triode of 5 response to the start signal, battery 3| is discontube 46 are derived provide for varying the cathnected from the control anode of tube l1 and ode potential with respect to ground without becomes connected to the control anode of tube changing the plate-to-cathode potential. This l8. Thus the voltage of battery 26 reduced by pr i r orientation of the p v pluses nthe potentiometer comprising resistors 13 and 1| erated in the secondary of transformer 66 with g is applied across the control gap of tube l1 and respect 0 e oscillatory y es generated by the the opposing voltage of battery 3! is applied discharge tube oscillator, by which is meant that a r th t l gap of b |a These condi the time of occurrence of the positive impulse in ti ns do not of themselves change the operathe secondary of transformer 66 relative to each tive condition of tubes [1 d is because th cycle of oscillation Of the oscillator may b6 varied. :5 oltage applied acros the control gap of tube The terminal of the secondary of transformer n assumed to be f the Order f fifty n-, is 55 Which is negative When the right-hand triode insufficient to fire that control gap and the reducof tube 46 passes from conductive to non-conduction in vomage across the control gap of tube 3 tive condition is connected through conductor 12, to a few Volts or to zero cannot deactivate the resistor i3 and resistor 24 to the positive terminal tube. The first cycle of oscillatory current gem of battery f throng? reslstor H to grounderated by the oscillator as a result of reception of The otheli termmal of me secondary of trans the start signal results in the production of a former 66 15 connected by conductor it to branch- Voltage across the Secondary of transformer 55 at ing circuits through resistors '55 and ll to the control anodes of cold cathode gas-filled discharge tubes ll and i8, respectively. Referring again to the system for controlling transmitting relay is, it will be noted that a potential difference is applied by battery 26 across the control gaps of the tubes l1 and I 8 and the n circuits for the application of these potentials are from the positive terminal of battery 136 through resistor 25, resistor I3, conductor 12, secondary of 2351 32 3?ciiii i fi h A5 d-uctor M, resistor 15, .control anode and cathode winding of relay 9 to ground which is at the of tube H and right-hand winding of relay l9 to tential of the negative terminal of battery 24, ground The aldmg V1tage m the Secondary of and through resistor '51, control anode and cathtransformer 65 is also apphed through reslstor ode of tube l8 and lefthand winding of relay H! H and across control gap of tube as through to ground. In the case of tube H, with the arthe left'hand Wmdmg of relay to groundbut mature f relay H on the marking Contact a, the voltage of battery 28 aided by the voltage in a timed instant just before or just after the middle of the cycle of oscillatory current as determined by

potentiometers

59 and 83. The voltage developed across the secondary of transformer 66 aids the potential difference across the control gap of tube ll applied by battery 28, as may be observed by tracing the circuit from the positive terminal of battery 26, through resistors 24 and I3, conductor 12, winding of the secondary of transformer $6 from negative to positive end, conreverse voltage is applied from the negative terthe secondary of transformer and Opposed by minal of battery 3! through resistors 29 and 25, the voltage of t y 31 is below the firing p d t- 23, armature and marking Contact f tential of tube 18. This is of no immediate conrelay H, resistor I4, control anode and cathode of 55 Sequence as tube has been assumed to be 0011- tube n and right-hand winding of relay [9 to duetive at s time T voltage suppl e y ground, which is at the potential or the positive battery 6 assumed to e f the order of y terminal of battery 3|. The voltage across the volts, aided by the voltage of r s o m r control gap f tub 11 i thus e n t b th difwhich will also be assumed to be of the order ofference between the voltages supplied by batteries fiftylolts, Produces a p t nti l i r ce a r ss 26 and 3 l, and this difierence may be zero so that the control g p of tube ll of the order of one hunthere is no potential across the control gap of tub dred volts which is sufficient to fire the COl'ltIOl gap H, or battery 26 may be of slightly higher voltand, accordingly, the main gap between the main age than battery 3!, so as to app1y a, positive poanode and the cathode of tube 51 becomes contential difference of a few volts to the control 05 ductive and the right-hand winding of relay i9 is anode with respect to the cathode, provided such energized. The firing of the main gap of tube potential difference is well below the firing poll results in the production of an impulse through tential of the control gap. Since, with the armacondenser 2'! to the main anode of tube is which ture of relay 1 l engaging the marking contact, reduces the potential of the anode relative to the battery at, is disconnected from the control anode 70 ath below e discharge sustaining p i l. of tube l8, the potential of battery 26, reduced Accordingly, the main gap of tube it from main by the voltage divider comprising resistors 53 and anode to cathode is renderednon-conductive and H, is applied across the control gap of tube i8, the leftrhand winding of relay I9 is deener ized. with the positive potential applied to the control The right-hand winding therefore assumes conanode. This potential should be well below the trol of the armature and moves the armature to the spacing contact, thus impulse on transmitting line 2|. i

Assuming that the voltage developed across the secondary of transformer 66 should persist after the main gap of tube l8 has been quenched, the control gap will not be fired, due to the fact that the voltage across this gap resulting from the battery 25 aided by the voltage in the secondary of transformer 65 but opposed by the voltage of battery 3| is below potential. It is to avoid the undesired refiring of tube l8 that the voltage developed across the secondary of transformer 66 should be sufiicient to fire the control gap of the tube l1 or tube l8 with the aid of battery 26 only when unopposed by the battery 3| but should not be'suflicient to accomplish this when opposed by the battery 3|.

When the armature of relay H is again restored to marking in response to a marking signalin the received code combination the opposing efiect of battery 3| will be removed from tube l8 and will be applied to tube H. The firing of tube l8 will await the production of the impulse of the proper polarity in the secondary of transformer 66 under the control of the oscillator, and when the impulse is generated the control gap and then the main gap of tube I8 will be fired and the main gap of tube i! will be quenched, whereupon the left-hand winding of relay l9 will move the armature to the marking contact. From the foregoing it will be apparent that relay I9 is operated by the commutating tubes l1 and 8 under the control of relay as to marking and spacing conditions and at timed intervals as determined by the oscil lator. Thus the oscillator determines the several instants at which relay l9 shall move its armature from one contact to the other and signaling impulses received in weak or distorted condition will be retransmitted as full length and full strength impulses. The orientation feature afl'orded by the

potentiometers

59 and 63 enables the right-hand triode of tube 46 to eifect the operation of tube I! or tube |8 when the most effective part of each signaling impulse is being received by the relay so that the armature of the receiving relay will have arrived at its proper selective position when the impulse for firing one of the commutating tubes I! and impressing a spacing |8 is generated. When two successive impulses 4 in a code combination are alike, the armature of relay H is in the same position when the positive impulse is generated in the secondary of transformer 68 for each of the two signaling impulses, so that the control gap of the same one I of the tubes I! or H; is retired in response to the second impulse. Since the main gap of the refired tube is already conducting, the refiring I of the control gap has no effect.

At the same time that the grid of the righthand triode section of tube 46 is made positive with respect to ground through the resistor 69 under the control of the oscillatory circuit the grid of the right-hand triode section of a tube 8| is made positive with respect to its grounded cathode under the same control through a resistor 82. The anode of the right-hand triode section of tube 8| is connected through the primary of transformer 83, which is shunted by resistor 84, and through resistor 86 to the positive terminal of grounded battery 81. The righthand triode of tube 8| is thus rendered conductive once for each cycle of the oscillator and when current rises in its anode circuit an impulse is generated in the secondary of transformer 83, one terminal of which is connected the control gap firing erates as a diode.

through resistor 29 to the negative terminal of grounded battery 3| and the other terminal of which is connected to the grid and anode of the left-hand triode section of tube 8| which, having its grid and anode connected together, op-

The impulse generated in the secondary of transformer 83 as current rises in the anode section of the right-hand triode is positive toward the anode and grid of the lefthand triode section and negative toward the battery 3|. The voltage developed across the secondary of transformer 83 is suflicient to overcome the negative voltage applied by battery 3| so that the interconnected anode and grid are made sufficiently positive for the tube to be conductive. The voltage of opposite polarity which is generated in the secondary of transformer83 when the grid of the right-hand triode section of tube 8| is restored to negative with respect to the cathode and current is cut on in the right-hand triode section, has no effect on the diode-connected left-hand section of tube 8| since that section is conductive in only one direction.

The cathode of the left-hand section of tube 8| is connected through a variable resistor 88 to the grid of the right-hand triode section of a twin triode electron discharge tube 89 and is also connected to one side of a condenser 9| the other side of which is connected to the anode of the left-hand triode section of tube 89. Each time that the left-hand section of tube 8| is conductive the flow of cathode current causes a charge to be impressed upon condenser 9| which is positive on the side of the condenser connected to the grid of the right-hand triode section of tube 89. The ircuit is so adjusted that when a full permutation code signal has been received, which, in the case of a code having five selecting impulses is sometimes called a seven-unit code if the start and stop impulses are each of one unit impulse length, or a seven and one-half unit code in case the start impulse is of one code impulse unit length and the stop pulse is of substantially one and one-half code impulse unit length, the condenser 9| will have received seven charging impulses under the ontrol of the seven cycles of oscillatory current generated by the oscillator and the seven accumulated impulses raise the potcntial of the grid sufliciently with respect to the grounded cathode to render the right-hand section of tube 89 conductive. The anode of the right-hand section of tube 89 is connected through resistor 92,

conductors

93 and 84 and resistor 86 to the positive terminal of grounded battery 81. The anode of the right-hand section of tube 89 is also connected to one side of a condenser 96 the other side of which is connected to the grid of the left-hand triode section of tube 89 and is also connected through resistor 91'to ground. Due to the flow of anode current in the right-hand section of tube 89 the potential of the anode becomes less positive, which causes condenser 96 to discharge, thus producing a flow of current through resistor 91 and driving the grid of the left-hand section of tube 89 more negative than the ground potential which it had when no current was flowing through resistor 91. The left-hand triode section of tube 89 is normally conductive and when the potential of the grid is made negative with respect to the grounded cathode, current in the left-hand triode section is cut off. The anode of the left-hand section of tube 89 is connected through resistor 98 and primary winding of transformer 99 to conductor 94 and thus to the positive terminal of battery 87. The right-hand end of the secondary winding of transformer 99 is connected to the control anode of discharge tube 34 and the left hand end of the secondary winding is connected to the cathode of that tube. The impulse generated in the secondary of transformer 99 when current in the left-hand section of tube 89 is cut on is positive toward the control anode of discharge tube 34 and negative toward the cathode and is of suflicient voltage to fire the control gap of tube 34. If receiving relay H is at this time in marking position which it should be in response to the stop impulse, battery 3! is connected to the cathode of tube 34 so that the main gap of the tube will be fired. Since at this time the oscillator has produced seven complete cycles, and since its decrement is substantially Zero, current and voltage conditions in the oscillatory circuit have returned to their initial values. The firing of tube 34 therefore merely holds the oscillator and no stopping transient results. If, however, the decrement is other than zero, the final amplitude will differ from the initial amplitude. To take care of this condition, the values of resistances 25 and 33 are so chosen that the circuit return to its initial condition in critically damped manner and the stopping transient is of the shortest possible duration. Thus the production of timing impulses is suspended and the system awaits the reception of the next start impulse.

When the anode current was cut off in the lefthand section of tube 89 the anode potential was made more positive which, through condenser 9|, makes the grid of the right-hand triode section of tube 88 more positive. Not only does the right-hand triode section of tube 39 continue to be conductive after anode current in the lefthand section has been cut off; but due to the positive potential of the grid it draws current thus charging condenser 9|. After a short while condenser 83 charges through resistor 91 thus bringing the grid of the left-hand section of tube 39 to ground potential and reactivating the left hand section of the tube. With the restoration of anode current in the left-hand section of tube 89 the anode potential of that section is made less positive by virtue of the flow of current in resistor 93. and trough condenser 9| the grid of the right-hand triode section is driven to negative potential with respect to the grounded cathode thus cutting off anode current in the right-hand section of the tube and restoring the system to normal.

Had the received signal combination been so distorted that the stop signal was not being received at the time the voltage developed across the secondary of transformer 99 fired the control gap of tube 34, the main gap of tube 34 would not have been fired because of the absence of negative battery connection for the cathode of tube 34 at the marking contact of relay l I' since presumably the armature of relay 1 I might not have returned to marking position. Under these circumstances the oscillator would not be stopped but would continue to produce timing cycles of oscillatory current from which impulses would be derived for charging condenser 9| and when seven cycles of oscillatory current had been generated the right-hand triode of tube 89 would again be activated and the control gap of tube 34 would again be fired eeking to reestablish the main gap discharge in the tube 34 under the control of the armature of receiving relay H. It should be noted that when the left-hand triode section of tube 89 is restored to conductive condition under the control of the right-hand triode section, an impulse is generated in the secondary of transformer 99 of the opposite polarity to that which refired the control gap of tube 34. Since the main gap of the tube has already been rendered conductive, the application of the reverse voltage across the control gap will have no efiect.

Fig. 2 shows a regenerative repeater similar to that shown in Fig. 1 but differing in two principal respects, namely, the provision of a counting chain of electron discharge tubes instead of the impulse accumulating condenser system for counting the oscillator cycles to determine when the oscillator shall be stopped and the provision of a capacity coupling instead of transformer cou-'- pling for the timing control of the firing of the control gaps of the commutating tubes which control the transmitting relay. The oscillator circult and the circuit for controlling its operation are identical with those shown in Fig. 1 and the same reference numerals have been applied thereto. The tube circuit for deriving impulses from the oscillator circuit for supplying the timing pulses for the commutating tubes is also identical except for the capacity coupling. Corre spending elements of the signal receiving mechanis'm and of the signal transmitting mechanism including the signal transmitting relay, the commutating tubes and controlling circuits also carry" the same reference numerals. In Fig. 2 all circuit elements which do not appear in Fig. 1 whether they represent substitutions for elements appearing in Fig, 1 or additional elements, are identified by reference numerals above 100.

In the system shown in Fig. 2, when the receiving relay I l responds to the start signal its armature disconnects battery H from the cathode of tube 35 thereby quenching the main gap discharge in the tube and permitting the oscillator to start generating cycles of oscillatory current. Pulses derived from the oscillatory circuit are applied through conductor 68 and resistor 69 to the grid of the right-hand triode section of tube 46 to render the tube alternately conductive and non-conductive. The anode circuit of the righthand triode section of tube 46 instead of includ-- ing the primary of a transformer as in Fig. 1 includes a resistor Hll between the anode and the movable contact of potentiometer 63. The anode of the right-hand triode section of tube 46 is also connectedby conductor N32 to one side of each of the condensers I03 and Hi l. The other side of condenser W3 is connected to the control anode of tube ll through resistor Hi6 and the other side of condenser Hit is connected to the control anode of tube IS through resistor I01. In view of the elimination of the transformer, the conductors I2 and M which included. the secondary of the transformer are replaced by con-'' ductor' 108 which extends directly from the righthand end of resistor 13 to the point of interconnection of resistors l6 and H.

The conditioning voltage for the control gaps of tubes ii and I8 is supplied directly to the control anodes of those tubes from the positive terminal of battery 26 through

resistors

24 and 13, conductor H38 and branching through resistor it. through a resistor Hi9 which is connected between the upper end of resistor 16 and the upper side of condenser H33, and through the resistor N35 to the control anode of tube IT and in the other branch through resistor 11, a resistor Ill connected between the lower end of resistor 11 and the lower side of condenser I04, and through resistor 107 to the control anode of tube I8. The

fiollditibhing voltage is opposed on the side which is engaged by the armature of relay I I, by the voltage supplied by battery SI.

With the right-hand triode of tube 45 nononductive, condensers I03 and I04 are charged by the voltage appearing at the point of contact of the movable contact of potentiometer 63 with the potentiometer winding through a circuit including resistor IOI, conductor I02 and in one branch through condenser I03, resistor I 09, resistor 16, conductor I08, and resistor H to ground and in the other branch through condenser I04, resistor III, resistor 11, conductor I08 and resistor TI to ground. When the right-hand triode of tube 46 is rendered conductive, the potential of its anode is reduced, thus partially discharging condensers I03 and I 04 and thereby making the upper plate of condenser I03 and the lower plate of condenser I04 less positive. These potentials are in opposition to the voltages applied across the control gaps of tubes I1 and I8 supplied by battery 26 so that the voltage across the control gaps of tubes I1 and I8 is reduced while condensers I03 and I04 are discharging but the voltages are restored to normal value when the condensers reach a steady state during the period that the right-hand triode of tube 46 is conductive. When current is cut off in the right-hand triode of tube 46 the potential of the anode rises to its original value thus recharging the condensers I03 and I04. The potentials on the upper plate of condenser I03 and on the lower plate of condenser I04 increase and these potentials are applied to the control anodes of tubes I1 and I8 in aiding relation to those supplied by battery 26 so that the tube from which the opposing effect of battery 3I was removed, namely, the tube I1, since the armature of relay I I has been as sumed to have moved to spacing in response to the start signal, becomes conductive in its control gap and thereupon immediately in its main gap. From this it will be apparent that tube I1 or tube I8 is rendered conductive upon the cessation of current in the right-hand triode of tube 46 as in the arrangement shown in Fig. 1, with the difference that the firing potentials are applied across the control gaps of the tubes by means of condensers in aiding relation to battery 26 instead of by transformer coupling,

For counting the cycles of oscillatory current generated by the oscillator, there is a triode tube II 6 which controls a counting chain of cold cathode gas-filled electron discharge tubes ofwhich tube II1 corresponds to the start pulse, tubes II8 to I22, inclusive, correspond to the five selecting impulses of a permutation code and tube I23 corresponds to the stop pulse. of the tubes II1 to I 23, inclusive, the left-hand electrode is the cathode, and the uppermost electrode is the main anode. The cathode of each of the seven tubes is connected through an individual resistor I 31, which is shunted by a condenser I38, to conductor I26 which extends through resistor 29 to the negative terminal of battery 3|, the positive terminal of which is grounded. The main anode of each of the tubes II1 to I22, inclusive, is connected to a conductor I21, which is connected to a voltage divider comprising resistors I 30 and I 35, bridged between battery 26 and ground. The main anode of tube I 23 is connected by conductor I28 through the primary of a transformer I29 to the same voltage divider. I43 is connected in parallel A varistor I42 shunted by a condenser with the primary of transformer I29; The characteristic of varistor I42 is that it exhibits relatively low impedance to flow of current in one direction and exhibits extremely high impedance to flow of current in the opposite direction. The purpose in providing varistor I42 is to provide a low resistance path for quickly dissipating the energy of the voltage developed in the primary of the transformer when current therethrough is cut off, thereby to prevent the induction of a voltage across the secondary, and to prevent the rapid dissipation of the energy of the voltage devel-- oped when current rises in the primary, thereby permitting a voltage to be induced across the secondary.

The cathode of each tube is connected to the control anode of the next tube in the series by a resistor I3I and the cathode of the last tube I23 in the series is connected to the control anode of the first tube II1 through conductor I 32 and a similar resistor I3I. A condenser I 33 is connected between the control anode of each of the tubes II1 to I23, inclusive, and a conductor I34 which extends through the secondary winding of a transformer I36 to ground.

During idle intervals tube I23 is conducting in a circuit from the negative terminal of battery 3|, through conductor I26, cathode resistor I 31 associated with the cathode of tube I23, cathode to anode space discharge path of the tube, conductor I28, primary of transformer I29 and resistor I35 to battery 26. Due to the flow of current through the cathode resistor I31 of tube I 23, a voltage drop exists across this resistor and across the condenser I38 in parallel with it, the polarity of which is negative toward conductor I26 and positive toward conductor I32. Since conductor I26 is connected through the cathode resistor associated with tube I I1 to the cathode of that tube and conductor I 32 is connected through the resistor I3I associated with tube II1 to the control anode of that tube, the voltage across the cathode resistor I31 associated with tube I 23 is impressed across the control gap of tube II1 with the left-hand or control anode positive with respect to the cathode which is the right-hand electrode. It may be noted that the cathodes of all of the other tubes I I8 to I22, inclusive, are at the same potential as conductor I26 but only the control anode of tube I I1 is at a potential more positive than these cathode potentials because the cathode potential of the conducting tube I23 is applied to the control anode of tube II1 only. This potential is insufficient to fire the'control gap of tube II1.

Upon the production of the first cycle of oscillatory current by the oscillator in response to the start signal, the potential of the grid of triode tube IIE with respect to the grounded cathode is raised by a pulse applied through resistor 82 and tube H6 is rendered conductive. The anode circuit of tube II 6 extends through the primary of transformer I36, resistor I39, conductor I4I, resistor 24 to the positive terminal of battery 26, the negative terminal of which is grounded. The rise of anode current in the primary of transformer I36 induces a voltage across the secondary which applies an impulse through the condensers I 33 associated with the control anodes of all of the tubes I I1 to I23, inclusive. The polarity of the impulse is such as to make the control anodes of all of the tubes more positive with respect to the cathodes and in the case' of tube II1 the control anode of which has already been made more positive than the cathode as previously explained, the control gap is fired, whereupon the main gap becomes conductive. None of the tubes IIB to I22, inclusive, also becomes conductive because conditioning voltages had not been applied across their control gaps and the voltage supplied by the secondary of transformer I36 is insufficient to fire the control gaps of these tubes.

At the instant that the main gap of tube II1 fires, the potential difference between the main anode and the cathode which, when the tube is non-conductive is higher than the discharge sustaining potential but is insufiicient to directly fi-re the tube through the main gap, decreases to the discharge sustaining potential. This decrease occurs before the discharge current has flowed into condenser I38 associated with the cathode of tube II1 sufiiciently long to develop a voltage across the condenser. Tube I23 has been conducting up to this time and the discharge sustaining potential difference has existed between its main anode and the cathode. An additional potential difierence has existed across the cathode-resistor I31 and condenser I38 associated with tube I23 due to the fiow of the discharge current. However, upon the firing of the main gap of tube II? and before discharge current has begun to flow in resistor I31 associated with tube III, the potential difference between the main anode and the cathode of tube II1, which is the discharge sustaining potential and is lower than the potential difference appearing across those electrodes when the tube was nonconductive, appears directly between conductors I21 and I26 due to the fact that there is no voltage drop in the resistor I31 associated with tube H1. The anode of tube I23 is connected to conductor I21 through conductor I28 and the primary winding of transformer I29 and the resistor I31 associated with the cathode of tube I23 is connected to conductor I26 so that the potential difference between the main anode and the cathode of tube I23 plus the potential difference acres the associated resistor I31 and condenser I38 is reduced to a value equal to the discharge sustaining potential between the main anode and the cathode of tube H1. Since a portion of this reduced potential difference appears across resistor I31 and condenser I33 associated with tube I23, it follows that the potential difference between the main anode and cathode of tube I23 has been reduced below the discharge sustaining potential and, accordingly, current through the main gap of tube I23 is out off. Thus the firing of tube II1 results in the quenching of tube I23, and by virtue of the fact that the main anodes of all of the tubes are connected directly to a common supply circuit, the firing of any one of the tubes will result in the quenching of any other of the tubes that has been conducting.

With the cutting off of current in tube I23, cathode current in the resistor I31 associated therewith ceases and thereupon condenser I38 gradually discharges through resistor I31, thereby sustaining for a short while the positive potential on the cathode of tube I23. This affords time for tube I23 to become thoroughly deionized before the normal potential supplied from the negative terminal of battery 3I is reapplied to the cathode of tube I23. Were this time for deionization of the tube not afforded the tube I23 might refire directly through its main gap. Since the anode circuit of tube I23 includes the primary of transformer I29, the dying out of current in this circuit would produce a voltage across 14 the secondary of the transformer were it not for the fact that v-aristor I42 shunted by condenser I43 is connected across the primary of transformer I29 with its direction of low impedance conductivity so related to the voltage developed that the primary of the transformer-is practically short-circuited and is ineffective to develop a voltage across the secondary due to the dying out of the anode current. The secondary of transformer I29 is connected across the control gap of tube 34 the same as the secondary of transformer 99 in Fig. 1 and thus the firing of the control gap of that tube is not accomplished by the quenching of tube I23.

With the development of a voltage across resistor I31 and condenser I38 associated with tube N1, the potential of the control anode of tube I-IB with respect to the cathode is made more positive in the same manner that the control gap of tube II1 was conditioned by tube I23 and,

I accordingly, tube H8 is prepared to be rendered conductive. Under the control of the second cycle ofosoillatory current generated by the oscillator, triode tube III) is rendered conductive mementarily and a voltage is developed across the secondary of transformer I36 which, through condenser I33 associated with the control anode of tube IIB, further raises the potential of the control anode and the control gap of the tube is fired, followed immediately by the firing of the main gap. Since the main anode of tube H8 is connected to the main anode of tube II1, the reduction in voltage across the main gap of tube II8 to the discharge sustaining potential, which occurs before current flows through resistor I31 associated with tube II8, results in the reduction of the potential of the main anode of tube II1 with respect to its cathode so that the potential difference between the main anode and the cathode is less than the discharge sustaining potential and tube H1 is accordingly quenched in the same manner that that tube, when it was rendered conductive, quenched the tube I23.

In this manner, successive cycles of the oscillator effect the firing of successive ones of the tubes in the counting chain and each tube upon being fired quenches the tube ahead of it. In response to the end of the seventh cycle of the oscillator which occurs during the stop impulse of the received signal, tube I23, which was conditioned by tube I22, becomes conductive and in turn quenches tube I22. The rise in anode current for tube I23 through the primary of transformer I29 results in the production of a voltage across the secondary of the transformer without hindrance by the varistor I32 and the voltage developed is positive with respect to the control anode of tube 34 and negative with respect to the cathode. The control gap of tube 34 is thus rendered conductive and if the armature of receiving relay II is at this time in marking condition, which it should beif the received signals are not so badly distorted that the stop signal is not being received, the main gap of tube 34 will be fired and the oscillator will be stopped. In this way the apparatus will be restored to the initial condition with discharge tubes I8, 34 and I23 conductive and all others non-conductive.

It is to be noted that a varistor was not provided in shunt with the primary of transformer 99 in Fig. 1 whereas it is provided in shunt with the primary of transformer I29. The reason for this is that there is a different interval between the starting and stopping of current through the primary of transformer 99 than there is between the starting and stopping of current in the primary of transformer I29. In the case of the transformer 99 current normally is flowing in the primary because the left-hand triode section of tube 89 is normally conductive. It is rendered non-conductive, to fire tube 34, and is almost immediately restored to conductivity under the control of the right-hand triode section of tube 89 so that the reversed impulse in the secondary of the transformer follows the control gap firing impulse almost immediately and has no effect on tube 34. In the case of the transformer I29 no current is flowing in the primary during the reception of a code combination due to the fact that tube I23 is quenched. Tube I23 is fired under the control of the seventh cycle of the oscillator to produce an impulse in the secondary of transformer I29 which fires the control gap of tube 34. Thereafter upon the reception of the start impulse of the next signal combination the main gap of tube 34 is quenched, the oscillator is started and produces its first cycle, the end of which causes the firing of tube III which, in turn, quenches tube I23. The stopping of anode current for tube I23 through the primary of transformer I29 would produce a voltage across the secondary of transformer I29, were it not for the provision of varistor I42, which voltage would be negative toward the control anode of tube 34 and positive toward the cathode. It is a characteristic of some types of gas-filled cold cathode tubes that the control anode and the cathode are identical and may be employed interchangeably. Thus the failure to suppress the reverse firing of the control gap of tube 34 in response to quenching of tube I23 might result in firing of the main gap of tube 34 and stopping of the oscillator whereby the retransmission of the received signal combination would be disturbed and a garbled or incorrect signal would be transmitted.

Although certain specific embodiments of the invention have been shown in the drawings and described in the foregoing specification, it will be understood that the invention is not limited to such specific embodiments but is capable of modification and rearrangement Without departing from the spirit of the invention and Within the scope of the appended claims.

What is claimed is:

1. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, means for counting the impulses generated by said impulse generator, and means operated by said counting means upon counting a predetermined number of impulses for stopping said generator.

2. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, electron discharge means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, means for counting the impulses generated by said impulse generator, and means operated by said counting means upon counting a predetermined number of impulses for stopping said generator.

3. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, normally conductive electron discharge means rendered non-conductive by said signal responsive relay upon response of said relay to a signal for activating said impulse generator, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, means for counting the impulses generated by said impulse generator, and means operated by said counting means upon counting a predetermined number of impulses for rendering said electron discharge means conductive whereby to disable said generator.

4. In a telegraph signal repeater, a signal'responsive relay, a normally inactive electronic generator of oscillatory current, means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled by said generator for deriving impulses at the rate of at least one impulse per cycle of oscillatory current, means controlled jointly by said signal responsive relay and said impulse deriving means for operating said transmitting relay, means for counting the cycles of oscillatory current generated by said generator, and means operated by said counting means upon counting a predetermined number of cycles for stopping said generator.

5. In a telegraph signal repeater, a signal responsive relay, oscillator for generating oscillatory current, means controlled by said relay for setting said oscillator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said oscillator for operating said transmitting relay, means for deriving impulses from said oscillator at the rate of one impulse per cycle of oscillatory current, means for counting said impulses, and means operated by said counting means upon counting a predetermined number of impulses for stopping said oscillator.

6. In a telegraph signal repeater, a signal responsive relay, a normally inactive electronic oscillator for generating oscillatory current, means controlled by said relay for setting said oscillator in operation, a signal transmitting relay, 8. first impulse deriving means for deriving impulses from said oscillator at the rate of one impulse per cycle of oscillatory current, means controlled jointly by said signal responsive relay and said first impulse deriving means for operating said transmitting relay, a second impulse deriving means for deriving impulses from said oscillator at the same rate as said first impulse deriving means, means for counting the impulses derived by said second impulse deriving means, and means operated by said counting means upon counting a predetermined number of derived impulses for stopping said oscillator.

7. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, an electron discharge device having a control grid, a condenser associated with said grid, means for deriving impulses from said generator and for impressing charges on said condenser cumulatively to render said electron discharge device conductive after the accumulation of a predetermined number of charges, and means controlled by said electron discharge device upon being rendered conductive for stopping said generator.

a normally inactive electronic 8. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse-generator, means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, means for deriving impulses from said generator, a normally non-conductive electron discharge device having a control grid and a condenser associated with said grid, means controlled by said impulse deriving means for cumulatively charging said condenser according to the number of'impulses derived from said generator for raising the potential of said control grid step by step to ultimately render said electron discharge device conductive, means controlled by said electron discharge device upon being rendered conductive for stopping said generator, and means for discharging said condenser whereby to restore said electron discharge device to non-conductive condition.

9. In a relay system, a controlling relay, a pair of cold cathode electron discharge tubes having main and control discharge paths, means for .applying across the control paths of both tubes a potential difference less than the firing voltage of said control paths, means for cyclically applying across the control paths of both of said tubes a potential difference in additive relaton to said first-mentioned potential difierence, the aggregate of which exceeds the firing potential of said control paths, and means controlled by said relay for selectively applying across the control path of one of said tubes a potential difference in subtractive relation to the other potential differences whereby to maintain the potential difierence across the control path of said one tube below the firing voltage.

10. In a relay system, a controlling relay, a pair of cold cathode electron discharge tubes having main and control discharge paths, one of said tubes being normally conductive through its main dis-charge path, means for continuously applying across the control paths of both tubes a potential difference less than the firing voltage of said control paths, means for cyclically applying across the control paths of both of said tubes a potential difference in additive relation to said first-mentioned potential difference, the aggre 1 gate of which exceeds the firing voltage of said control paths, means controlled by said relay for selectively applying across the controlpath of either of said tubes, a potential difference in subtractive relation to the other potential differences whereby to maintain the potential difference across the control path of the selected tube below the firing voltage, and means effective upon the firing of the main discharge path of either tube under the control of its control discharge 1 path for quenching the discharge through the main discharge path of the other tube.

11. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, a series of electron discharge devices operable successively by said impulse generator and means controlled by the last electron discharge device in said series for deactivating said impulse generator.

12. In a telegraph signal repeater, a signal responsive relay, a normally inactiveimpulse gentrolled by said predetermined one of erator,means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, a closed ring of. electron discharge devices having a predetermined one of said electron discharge devices normally conductive and the remainder non-conductive, means controlledby said impulse generator for rendering said non-conductive electron discharge devices conductive in succession, means effective ,upon any one of said electron discharge devices becoming conductive for renderingnonconductive any other of said electron discharge devices which is then conductive, and means consaid electron discharge devices upon being again rendered conductive for deactivating said impulse generator.

13. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, a plurality of electron discharge devices arranged in a closed ring circuit, a predetermined one of said electron discharge devices being normally conductive and the remainder being normally non-conductive, means intervening said electron devices in said circuit whereby each tube upon being rendered conductive prepares the next tube to be rendered conductive, means controlled by said impulse generator for impressing tube firing impulses on said ring circuit whereby said tubes are fired in succession as prepared, means efiective upon each of said tubes becoming conductive for rendering nonconductive any tube which is then conductive, and means controlled by said predetermined one of said tubes upon being again rendered conductive for deactivating said impulse generator.

14. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, a. normally conductive electron discharge device rendered non-conductive by said signal responsive relay upon response of said relayto a signal .for activating said impulse generator, a series of electron discharge devices one of which is normally conductive and the remainder of which are normally non-conductive, means controlled byv said impulse generator for rendering the tubes in said series conductive in succession by successive impulses generated by said impulse generatonmeanseffective upon any of the tubes of said series being rendered conductive for rendering non-conductive any other tube ,in said series which is then conductive, and means controlled by saidpredetermined one of said tubes upon again becoming conductive for rendering the first-mentioned electron discharge device conductiva whereby to deactivate said impulse generator.

15. In a telegraph signal repeater, a signal responsive. relay, .a normally. inactive impulse generator, a normally non-conductive cold cathode electron discharge tube rendered non-conductive by said signal responsive relay upon response of said relay to a signal for activating said impulse generator, said tube having a pair of spaced electrodes defining a non-polar control gap, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay. means comprising a closed ring circuitoi cold 19 cathode electron'discharge tubes for counting the impulses generated by said impulse generator, said ring circuit having one of the electron discharge tubes normally conductive, means associated with the anode circuit of said one tube for applying a potential difference between the electrodes defining the control gap of the firstmentioned electron discharge tube, and means for causing said potential difference to be impressed on said electrodes only upon the firing of the normally conductive tube in said ring circuit.

V 16. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse gen erator, a normally conductive cold cathode electron discharge tube rendered non-conductive by said signal responsive relay upon response of said relay to a signal for activating said impulse generator, said tube having a pair of spaced electrodes defining a non-directional control gap, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, a plurality of cold cathode electron discharge tubes arranged in a ring circuit for counting the impulses generated by said impulse generator, said ring circuit having a; predetermined one of the tubes contained therein normally conductive, a transformer having its primary winding in the anodecircuit of the normally conductive tube of said ring circuit and having its secondary winding connected to the control gap electrodes of the first-mentioned electron discharge tube, and means connected in shunt relation to the primary of said transformer having unilateral conductivity for estopping the generation of a potential difference in the secondary of said transformer upon the cessation of anode current in the normally conductive tube of said ring circuit.

17. In a telegraph signal repeater, a signal responsive relay having an armature operable between two contacts, a signal generating relay having an armature operable between two contacts, individual means of which one or the other is always operated for operating the armature of said signal generating relay in each direction be tweenits contacts, means efiective at the beginning of each transit of the armature of said signal responsive relay for conditioning the unoperated one of said operating means to be operated and effective .at the end of each transit for conditioning the other operating means to be deactivated, and timing means for operating the unoperated one of said operating means, said unoperated means, upon being operated, causing the other operating means to be deactivated.

18. In a telegraph signal repeater, a signal responsive relay having an armature operable between two contacts, a pair of electron discharge devices having their control electrodes connected to said contacts, a signal generating relay operable in opposite directions by said electron discharge devices, a source of potential of effective polarity but ineifective voltage also connected to the control electrodes of said discharge devices, a source of potential of opposite polarity connected to the armature of said signal responsive relay for opposing the potential applied to the control electrode of one or the other of said discharge devices only during engagement by said armature with one or the other of its contacts,

,means for producing timed impulses, and means controlled by said timing means for impressing a potential on the control electrodes of said discharge devices of the same polarity as the firstmentioned source of potential whereby to activate the discharge device from the control electrode of which the armature of said signal responsive relay has disconnected the opposing source of potential.

, 19. In a telegraph signal responsive device, a signal responsive relay, normally inactive means activated by said relay for generating oscillatory current, means for deriving impulses from said oscillatory current, means for varying the time relation of said impulses to the cycles of said current, and second means for deriving impulses from said current in fixed time relation to the cycles thereof v20. In a telegraph signal responsive device, a signal responsive relay, normally inactive means activated by said relay for generating oscillatory current, means for deriving impulses from said oscillatory current, means for varying the time relation of said impulses to the cycles of said "oscillatory current,

means controlled by said impulses for registering the signal responsive operation of said relay, second means for deriving impulses from said current in fixed time relation to the cycles thereof, and impulse counting means controlled by said second impulse deriving means.

21. In a telegraph signal responsive device, a signal responsive relay, normally inactive means activated by said relay for generating oscillatory current, means for deriving impulses from said oscillatory current, means for varying the time relation of said impulses to the cycles of said oscillatory current, means controlled by said impulses for registering the signal responsive operation of said relay, second means for deriving impulses from said current in fixed time relation to the cycles thereof, impulse counting means controlled by said second impulse driving means, and means controlled by said counting means upon counting a predetermined number of impulses for deactivating said current generating means.

22. In a start-stop telegraph signal responsive device, means for generating oscillatory current adapted to be started by one of a series of received impulses, and thereafter to generate cycles in approximate synchronism with said impulses and to be stopped at the end of said series, means for deriving timing impulses from said cycles, means for varying the time relation of said timing impulses to said cycles, means controlled by said timing impulses for registering said received impulses, second means for deriving timing impulses from said cycles in fixed time relation thereto, impulse counting means controlled by said second impulse deriving means, and means controlled by said counting means upon counting a predetermined number of said fixed time relation impulses for stopping said current generating means.

23. In a start-stop telegraph signal repeater, a signal responsive relay, means for generating oscillatory current adapted to be started by one of a series of signaling impulses received by said relay, and thereafter to generate cycles in approximate synchronism with the remaining impulses in said series and to be stopped at the end of said series, means for deriving timing impulses from said cycles, means for varying the time relation of said timing impulses to said cycles, a signal generating relay controlled jointly by said'signal responsive relay and said impulse deriving means, second means for deriving timing impulses from said cycles in fixed time relation thereto, impulse counting means 21 controlled by said second impulse deriving means, and means controlled by said counting means upon counting a predetermined number of said fixed time relation impulses for stopping said oscillatory current generating means.

24. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, a normally conductive cold cathode electron discharge tube rendered non-conductive by said signal responsive relay upon response thereof to a signal for activating said impulse generator, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for controlling said transmitting relay, and means for reactivating said electron discharge tube a predetermined interval after the deactivation thereof whereby to disable said impulse generator.

25. In a regenerative repeater for the retransmission of received telegraph signals, a repeating device, means for preparing said device for operation in accordance with the marking and spacing character of the received signals, and means including a counting ring circuit comprising a plurality of electron discharge tubes corresponding in number to the impulse units in the signals to be retransmitted for accurately timing in a predetermined manner the operation of said repeating device.

26. In a telegraph signal repeater, a signal responsive relay, a normally inactive impulse generator, electron discharge means controlled by said relay for setting said generator in operation, a signal transmitting relay, means controlled jointly by said signal responsive relay and said impulse generator for operating said transmitting relay, means for counting the impulses generated by said impulse generator, and means operated by said counting means upon counting a predetermined number of impulses for conditioning said electron discharge means in a manner to cause said impulse generator to restart its pulsing cycle upon the reception of a start signal impulse by said signal responsive relay.

WILTON T. REA. JEFFERSON R. WILKERSON.

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

UNITED STATES- PATENTS Number Name Date 1,771,446 Parker July 29, 1930 2,133,456 Kinkead Oct. 18, 1938