US2816250A - Electronic counting and computing arrangements - Google Patents

Description

J. R. ACTON Dec. 10, 1957 ELECTRONIC COUNTING AND COMPUTING ARRANGEMENTS Invenlor JOHN R. ACTON 5 21;

Filed July 19, 1956 I Attorneys United States Patent ELECTRONIC COUNTING AND COMPUTING; ARRANGEMENTS John Reginald Acton, Beeston, Nottingham, England, assignor to .E'ricsson Telephones Limited Application July 19, 1956, Serial N0; 598,856

priority, application Great Britain July 25; 1955 6;-Claims. (Cl. SIS-84.6)

The-present inventionrelates to. electronic: counting :and computing arrangements, and particularly; tosuch arrangementsv which include one or more gaseousdischarge tubesa eacha containing-a plurality. of electrode; discharge points spaceda uniform distance apart 'inaa-cringiaround andsequidistantfrom a common electrode.

It'is'an object-of my invention to' provide. improved volta'geestabilising arrangements forruse, and inrcombinatiomiwith the:aforesaidzj-dischargectubeswwhichhare; forginstance; described in United Kingdom patent application Numberi1,32.4/ 49 (Serial. Number; 7 12,"17'1).-. Thisrpatent application-relates to. a discharge tuberhaving aaplurality 2,816,250 Patented Dec. 10, 1957 5 of the potentialthereat within a determinedrange of of cathode electrode discharge: points: disposediequidistantly-from: the discharge surface. of a commonlian'ode electrode. In. such: a tube a discharge glow investing one :ofi;theeccatliodezdischarge points'is causedto' move-.10 another cathode. discharges point by way of two .intermediate; guidei:" electrodes in response to each impulse 'of'theranode of such tube isrprogressively reduced as the :number of disch'arges present in the: tube "increases; thus rendering unstable the value of the applied' potentials necessary, on the one hand, to produce furtherdischarges inxthestube, or, on the otherhand; to causethe existing discharg'es tomove from onecath'ode to another. drawback's of the known multi-electrode discharge tubes :will besset-forth in greater detail further below.

Thisipresent invention is in the nature of 'animprovementon" the impulse counting arrangements depicted The v andiidescri-bed in the aforesaidvpatent application Num- 1 her 32,0.72/53; and. overcomes the aforesaid drawback by providing inf-these arrangements means whereby the p0.-

ten-tial atf'the anode of a discharge tube containing aplurality of cathodes is maintained automatically 'at 'a subst-antially constant voltage without regard-to the number ofi' discharges existing in the discharge tubeand' the corresponding variations in the loadtherein.

According to my invention I provide an arrangement for 'counting-and storing electrical pulses comprisinga gaseous el'ectric discharge tube containing=an anode and aplurality of cathodes,- means for applying: a; pulse=to a cathodedn said discharge tube and storingit withi-n the discharge tube in the form of a discharge between theanode and said cathode, means forapplying a pulse to a plurality of cathodes in common and thereby causing a'discharge to: move from one cathode to. anotherzcathode, meanswhereby. an impulse stored in the. tube inithe form offazdischarge, is counted out from: saiditube impulse torm-,. in. combination. with anode potential. stabilizing :means,..whereb,yz a; potentiaLderii/ed from mired-current 1 .assembly as. described later.

values.

Againaccording to myinvention I provide voltage stabilising arrangements. for use with a variable load wherein aUpotential-derived.from a direct current, source is applied toan-ianode of a thermionicvalve, and-,a cathode. ofv said, valve is. connected to a cathode follower circuit, and wherein a: potential;at thelload is derived from said cathode of saidpvalvev and is maintained automatically at-a.value:within adeterminedrange of *values without regard to the value of the loadcurrent.

The. presentv invention .will now. be. more. fully described Withreference tojthe accompanying. drawing which shows a-. .simple embodiment of. my invention. Inthis. simple circuitarrangement I.provide. a gaseous discharge tube DTD. in whichthe discharge points of thirty electrodes are spaced a@ uniform ,distanceapart and arrangedin 1a ring;,around the dischargesurface, of a circular anode-A common. to} the, said. thirty electrodes; One or more auxiliary electrodes-maytalso be provided and be situated in suitable: positions. with respect to the mainvelectrode Each. electrode. in .the. tube DIDfis providedwith separate meansof accessfrom the containing bulb or envelope; Three half-waverectifying valves DIA, DIB.,. and DT C, with-a thermionictriode valvetDTErarealso included in the depicted arrangement. Forthe. purpose of .this description, ten of the;sai,d..thri ty electrodesjintubeDTD. will be termed cathodes and designateduTltto T10, ,a further.v ten. will bevvtermedwfirst guide. electrodes/and designated GA'1. to" GA10, andsthe remaininggtenQwill betermedsecond guideelectmdesand designated GB'1-to, GB'10.. When so termed,the,saidithirty electrodes, of. which apart only-areshown symbolically, are'jarr'anged. around'anode A inv theorder cathode. T1, first a guide we GA1,. second guidev (3B1, cathode T2,' and.- so

on in the same order withsecond guideGBIt).v adjoining cathode T1. v p I In this embodiment of my, invention theanode, oilvalve DTE is.-connected..to. the positive ppleof aqsourceiof Suit;- abledirec'tcurrent byway of lead'PA, andthe, negative pole. of.-'th'e said direct, currentsource isconnectedtoha zero. potential common. lead. 2., With anode A" of dis: charge tube- DTD'. connected. to, the. cathode, of. valve DTE,.,and.b'y way of. resistor R11 to zero p otentialilat lead' Z, ,the, said :resistor. R11, forms a cathode. followed. Also. connected by, way of. leadsPA and Z'.to thede} scrihed-direct-cur rentsource, which we will :term .themain sourceoflpotential, and'inparallel. withrvalve DTE isia potential. dividing. arrangement consisting of. resistors R13; R14- and-R15, three. half-wave... rectifying valves DTA, DTB-and DTC,,andj a further resistor, Rl,6., Re,- sistors R13:- andmR14 are. provided with means. whereby the: potentiabat. points x..and y, respectively may be varied for apurpose-which .will be described later. The. voltageatappingipointsxand-y are also. connected tothe grid electrode/of;valveDIE bymeans of unsymmetrical conductive elements MR1 .and MR2; resp ctively. Tapping pointsx and y are also-connectedtothe zero, potential commonlead Z.by,means of decoupling capacitors, 4 and C5 whichserve toensure that only thesteadyldirect current potential developed. at these, tapping, points is applied to the,g rid.oi.Ivalve.DTE. Valves.DTA',,,DIB and .DTC withtheir associated :resistorRlfi formra reference-voltagesou-rceh 1 I l V y,

Each-cathode T 1 to..-T 10 in discharge tuble..DTDl is connected way; of.v a separate resistor. R40; to,1{49 respectively. to. zero .potentialiatlead Z.. Whilst each. fiIst guideaGAL to GA10 .and.secondtg uide.,GBL to. CiBlOI is taken, by way of a resistor in the groups of resistors R30 to R39 and R20 to R29 respectively, to means whereby a suitable negative-going impulse may be applied sequentially to the said groups of first guides and second guides. In the simple circuit depicted on the accompanying drawing such means are formed by switches SW1 and SW2 which are connected to the commoned groups of resistors R3ti-R39 and R20-R29 respectively and to direct-current sources ND and NC.

The commoned group of resistors R40-R49 associated with the cathodes T, of tube DTD are connected to the grid of valve DTE by way of capacitor C1 and resistor R17, similarly resistor groups R30-R39 and R20-R29 are also connected to said grid by way of capacitor/resistor combinations C2/R18 and C3/R19 respectively. The capacitor in each such combination serves to prevent the main direct-current source from being short circuited by way of resistor R12.

When the pressure and content of the gaseous or other filling in the described tube and valves, the spacing of the electrodes therein, and the values of the described resistors, capacitors, and sources of potential are all suitable, a discharge is produced in tube DTD, and the glow thereof caused to invest cathode T1, when a pulse of suitable negative potential is applied to the said cathode Tl. Such a pulse may conveniently be derived by the brief application of the potential at terminal E to the point marked w. Such a discharge between anode A and cathode T1 is caused to move. and to invest cathode T2. when a pulse of suitable negative potential is applied sequentially to the first guides GA and second guides GB in that order. The discharge glow is caused to move to and invest cathode T10 however when the said sequential negative going pulses are applied to second guides GB and first guides GA in that order. Each such pair of sequential voltage impulses maybe derived from a single voltage pulse of suitable characteristics modified in known manner. or as in the simple arrangement shown on the accompanying drawing in which the sequential operation of switches SW1 and SW2 in that order cause a negative oing pulse derived from direct current sources ND and NC to be applied to the described groupsof first guides GA and second guides GB.

The production of such a single discharge in tube DTD causes current of a particular value to fiow through the tube DTD. This current is drawn from the main direct-current source, and its value remains substantially constant re ardless of the position of the discharge in the tube DTD. When however such a discharge has been caused to move in the manner described from cathode T1, and its glow invests, for example, cathode T4, the production of a second discharge in the tube in a similar manner will cause the current flowing through the tube to rise, and at the same time will tend to lower the value of the positive potential at anode A of the tube DTD. Each additional discharge produced in the tube DTD will have a similar effect and will tend to lower progressively the potential at anode A. Such changes to the value of the said potential are undesirable as they render unstable the value of the potentials which it is necessary to apply to the first and second guides GA and GB in order to move the discharges in the tube DTD from the cathodes T on which they are halted to other cathodes T. Thus it is desirable to maintain the potential at anode A of the tube DTD in the region of a particular value regardless of the number of discharges existing in the tube DTD, or of the positions of the electrodes invested by the discharge glows. Such a value potential will be termed the optimum value. 1

In this present invention the potential at the anode of the multi-cathode discharge tube DTD is maintained by means of a thermionic triode DTE in the region of an optimum value at all times that the tube contains one or more discharges. Triode DTE is arranged in a characteristic relationship to potentials derived from a main asiaaso source of direct current, to the electrodes of the multicathode discharge tube DTD, and to a potential dividing arrangement formed by asymmetrical elements MR1 and MR2 and resistors R13, R14, and R15 which is connected to valves DTA, DTB and DTC, which with resistor R16 form a reference voltage source. In the described arrangement of my invention the production of a discharge in tube DTD and the resultant flow of current through triode DTE causes a potential to be developed across resistor R11, and the positive potential at the electrode connected end of resistor R11 reaches a particular value. The production of an additional dis charge in tube DTD in the manner described previously, which tends to reduce the value of the positive potential at the said anode A of tube DTD, also tends to lower the value of the positive potential at the cathode of triode DTE and at the adjoining end of resistor R11. Such a tendency increases the potential difference between the cathode and grid electrodes of triode DTE, and causes the current flowing through triode DTE to increase, and in consequence the potential difference across the cathode follower resistor R11 returns to a value in the region of its previous value. In this way the tendency towards a lower positive potentials at the anode of tube DTD is reversed, and by choice of suitable components in the form of triode DTE and resistor R11 the potential at anode A is restored to a value which is equal, or substantially equal, to its previous value. This value may conveniently form the optimum value of positive potential at which it is desirable to maintain the anode A of tube DTD. Such a value of potential is determined by the potential difference across resistor R11, and is dependent upon the value of the current flowing in triode DTE. The value of the current in triode DTE is itself dependent upon the value of the potentials at its anode, cathode and grid electrodes. The potential at the anode of triode DTE is fixed as it is connected directly to the positive pole of the main direct-current source by way of lead PA. The grid electrode of triode DTE is held at a potential determined by the value of the positive potential derived from the main current source by way of resistor R12, and the potential derived from the reference .voltage source formed by valves DTA, DTB and DTC and resistor R16, in association with the potential dividing arrangement of resistors R13, R14, R15. The potential at the cathode of valve DTE is determined by the value of resistor R11, and a resistor of 100,000 ohms provides a satisfactory value of potential.

In one arrangement of the invention which has been found to be satisfactory the potential derived from the main current source is of the order of 400 volts, whilst the voltage of direct-current sources, NA, NC and ND is each of the order of 60 volts. The characteristics of triode DTE are such that it functions satisfactorily when the positive potential at the grid electrode is of the order of 250 volts, and the positive potential at points x and y is of the order of 260 volts and 240 volts respectively. With such an arrangement should the value of the positive potential at the grid of triode DTE tend to rise above the potential at point x current will flow through element MR1 and resistors R13, R14 and R15, and cause the value of the potential at the grid electrode to fall to the value of the potential at point x. Similarly should the value of the potential at the grid of triode DTE tend to fall below that at point y current will flow through element MR2 and resistors R16, R13 and R14, and cause the potential at the grid of triode DTE to rise to the value of the potential at point y.

When a discharge has been produced in tube DTD and a discharge glow has been caused to invest cathode T1 in the manner described, the subsequent application of a pair of suitable negative going pulses of potential sequentially to the first guides GA and second. guides GB, in that order, will have the effect of moving the said discharge fromcathode T1 to cathode T2- in the following manner. 0n the closure of switch SW1 the negative potential derived from direct-current'source NC is applied to resistors R30 to R39 and thence to first guides GAl to GA10, at the same time it is also applied to capacitor C2 and causes a negative-going pulse of potential to be'applied tothe grid electrode of triode DTE by way of resistors R18 and R17. The application of this first negative-going pulse of the said pair of pulses to the grid of triode DTE causes a reduction in the value of the current. through the said triode DTE with a consequent reduction in the value of the positive potential at the anode of tube DTD. At the same time the value of the potentialat first guides GA is made considerably more negative. Thus. conditions are pro duced in which the potential ditference between the anode A and cathode T1 in tube DTD isreduced simultaneously with an increase in the potentialdifierence between the said anode A and first guides GAl to GA10, and the potential difference between anode A and first guide GAl becomes so much greater than the potential difierence between the anode A andthe adjoining. cathode T1 that the discharge ceases to invest cathoderTl, and moves to and invests first guide GAl.

The second pulse of the pair of negative-going pulses is applied, by the closure of switch SW2, to second guides GBl to GBlt) by way of resistors R20 to R29, and to the grid of triode DTE by way of capacitor C3 and resistor R19. The second pulse is more negative than the first pulse as it is derived from direct-current sources ND and NC in series, and the negative-going pulse at the grid of triode DTE causes a further reduction in. the current through the said triode DTE, and a consequent lowering of the value of the positive potential at theranode of tube DTD. With second-guide GBl at a considerably more negative potential than the potential at guide GA1 conditions for the movement of the discharge again we vail, and the discharge moves to and invests second guide GB].. The reduction in the value of the current through triode, DTE, which occurs with the receipt of a pair of negative-going pulses of potential at the grid. of the said triode, is such as to cause the value of the positive potential at the anode A of the tube DTD to fall below the described optimum value, and following such pulses the described triode valve current and tube anodepotential are restored to their pro-pulsed values in the following manner. The application of the negative-going pulses to the grid of triode DTE reduces the positive potential at the said grid to a value below that of the positive potential at point y, and current flows through asymmetrical conducting element MR2 and causes the positive potential at the said grid to rise to a value in the region of the potential at point 3/. This increased positive potential at the grid of triode DTE causes the current through the valve to increase and to return to its pre-pulsed value.

The cessation of the pair of pulses by the opening of switches SW1-and SW2 in that order, and the con: currentincrease, inthe value of the positive potential at the anode A of tube DTD, produces conditions in which, when the value of the negative potential at second guide GBl falls below the value necessary to maintain a discharge, the potential difference between anode A and the adjoining cathode T2 has been restored to such a value that the discharge investing second-guide GBl is caused to move to and invest cathode T2.- In this way the application of a pair of negative-going: pulses of potential in sequence to the commoned groups of guide electrodes GA and GB causes the discharge to move from one cathode T to the next immediately adjacent cathode T. At the conclusion of such a movement the potential at the anode A of tube DTD is restored to a value in the region of the optimum value in the manner described.

With the said discharge investing cathode T2 a second discharge may be produced in tube DTD and caused to invest cathode T1 in a similar manner to that described with; reference" to the =fir'st-- discharge; Such an additional discharge causes the current'throughtube-DTD to increase, andxin consequence the-valueof the -positive potential atthe anode A of, the saidtub'e tend's=-to fall. This tendencytowards a lowervalue ofiposititie potential at tube- DTDis cornmunieated to the cathode of triode DTE; andcauses-the current through the sa-id trio-de to -increase until the value of the-positive potential at the anode of-- tube DTD and the adjoining end of resistor R11 is restored to a value in the region-ofithe optimum value.

Whentwo=discharges have been produced in the tube DTD each I operation ofiiswitches ;SW1: and SW=2tasadescribedswillica-use aapain of negative-going:pulsesto=be applied in sequence to: the. commoned first guides; GA and-commoned 'secondiguides GBPzandt thedischargesiwill move-'concurrentlyto and invest, the'next immediately adjacent cathode T=. During eacllksuch'zcyclte :of::movement the -potential? at :the1anodeeAaof tubetDTD 'isnvariedz; in the manner-describedito .facilitate the movement-10f the discharges; but: on. completionv of:; each cycle of movements-the positive potential; at; the SB-id) anode *A. isv restored. to v a, value in the regionuof thewoptimum value. Each additionalsdischarge produced in tube DTDawi-ll cause; the value-1 of;the current through the; said-tube to rise, andy-the value ,ofthe positiyevpotential at the anode of; the tube wilt-tend to ;=fa ll with each zsu. :h;in :reaseof current;- but will gbe hfeld a t;,a; :valuedn; the region ;of.- the optimum value {by theautomatic-voltage stabilizing-effect ofth potential. dividing-i arrangement in, association with triode DTE: and its cathode follower circuit arrangement.- With such, an arrangement a should the-value of the positive-potentiah at .the. gridclectrode of, triodeDTE rise-above the predetermined-value act-potential attp oint x current will fiowtby way of tasyrnmetrical conductingelementaMRl. and-the potentialat the triodeg ridiwillzb'e held. at the potential yalue-at-point x.

The describedarrangements for; guiding: a, discharge in. tube- DTD from ,onecathode: T, to the; next immediatel yadjacent cathode T.- are c equally suitable for use when a, sir 1g1e discharge.. exists; in...the---tube or. when,..the maximum number. of such, discharges haveibeen, pro: duced therein With. such discharge guiding arrangements the direction in which the discharge is guided around a ring. of cathode and guide electrodes maybeireversed by reversing the connections from switchies-SWland SW2 to the commoned-first guides-GA andTesistorsRSO to R39; and the commoned second guides-GB 'and resistors R20 to R29fi' Inorder 1 to maintain th'e-potential 'points x. and- 3 at aconstantgval-ueregardless of. variations: in: the :potential derived; from the; main source of direct current the potential 3 dividing-resistors R13, R14- and R15 :area arranged. in parallel with three-h alf wavevrectifyinggdiodes DTA, DTBQ andl-DTC as shown which with -.res istor;R16 form a,suitable..source of reference. voltagev The arrangementby which-the potential, at tanode A of tubeDTDjs maintained in the region .of apredetermined value when a number of discharges. in. the tube is increased to a maximum isalso satisfactory when anurnber. of discharges in the tube is-reduced to a minimum. Any reduction in the'numberof'discharge s in tube DTD"automaticall'y reduces the value-of the-currentthrough th'e'tube; and in" consequence the value of the positive potential 'at-anode A'tends to rise,- this voltage risingtendency'is communicated to the cath ode of triode valve DTE, and causesa reduction in the value of the current through triode DTE which reduction continues until the potential 'atanode A- of tube DTD, at the cathode oftriode DTE,and'at the adjoining end of thecathode followerresistor R11 is stabilised at a value-inthe region ofthedescribedoptimum. With such; an arrangementfitheinvestmentofi any cathodwl may be used to develop a potential across a resistor connected thereto, and such a potential may be applied to an output lead and form an outgoing pulse of potential. Such a resistor R2 and outgoing pulse lead OP are shown connected to cathode T1. In this way a plurality of discharges produced in a tube DTD, in consequence of the receipt of a like number of pulses, may cause a like number of impulses to be counted out, thus the arrangement may be regarded as a means of storing impulses.

An alternative means of producing a discharge in the multi-cathode tube DTD between anode A and a predetermined cathode T is provided in the invention by including switching means which are not shown on the drawing for disconnecting the positive potential applied to anode A, and providing at least one auxiliary electrode in the tube DTD. In one such arrangement the discharge point of an auxiliary electrode ST is situated in close proximity to the discharge point of the selected cathode T1, and the electrode ST is connected by way of switch SW3, terminal E, and resistor R1 to the negative pole of a source of direct-current NA. The gap between the discharge points of electrode ST and cathode T, and the potential derived from direct-current source NA 'are such that with switch SW3 closed a minute discharge is produced between the said electrodes. Electrode ST thus acts as a so-called keep-alight electrode and maintains the space around the discharge point of cathode T1 in an ionised condition. In the absence of a potential from anode A and with the associated switching means open, no discharge exists between anode A and cathode T. When the said switching means are closed a positive potential is applied to anode A, the ionised space around cathode T1 facilitates the production of a discharge between the said anode A and cathode T1, and a discharge glow invests the said cathode T1. In a variation of such discharge producing means which is not shown on the accompanying drawing, two auxiliary electrodes are provided in the multi-cathode tube and are connected by switching means to a suitable source of direct current. The auxiliary electrode discharge points are arranged to form a small discharge gap in a position adjoining a predetermined cathode T. In the absence of a discharge between the auxiliary electrodes the potential difference between the anode and the predetermined cathode T is insufficient to produce a discharge. When a discharge is produced between the auxiliary electrodes on the closure of the switching means the space around the predetermined cathode T becomes ionised, and under such conditions a discharge is provided between the anode and the said cathode T.

Although the voltage stabilising arrangement has been described with reference to a single discharge tube containing a plurality of discharge paths, its use is not confined to such tubes, and its application to many other forms of variable load will be obvious after this simple application of my invention has been understood.

What I claim is:

1. In an arrangement for counting and storing electrical pulses, comprising a gaseous electric discharge tube containing an anode and a plurality of cathodes, a direct-current source, the positive potential of which is applied to said anode, means for applying at least one pulse to one of said cathodes and storing the pulse within the discharge tube in the form of a discharge between said anode and said last named cathode, and means for applying a varying number of pulses to a varying number of said cathodes in common and thereby causing a varying number of discharges to move from one group of said cathodes to another group of said cathodes, thereby varying the load in said discharge tube; the improveinent of stabilizing means for maintaining automatically the value of the potential at said anode of said discharge tube stable within a determined range of values regardless of changes in the number of discharges in said discharge tube.

2. In an arrangement for counting and storing electrical pulses, comprising a gaseous electric discharge tube containing an anode and a plurality of cathodes, a directcurrent source, the positive potential of which is applied to said anode, means for applying at least one pulse to one of said cathodes and storing the pulse within the discharge tube in the form of a discharge between said anode and said last named cathode, and means for applying a varying number of pulses to a varying number of said cathodes in common and thereby causing a varying number of discharges to move from one group of said cathodes to another group of said cathodes, thereby varying the load in said discharge tube; the improvement of stabilizing means for maintaining automatically the value of the potential at said anode of said discharge tube stable within a determined range of values regardless of changes in the number of discharges in said discharge tube, said stabilizing means comprising a thermionic valve having anode means, cathode means and grid means therein, a cathode follower circuit associated with said thermionic valve and a reference voltage source connected in parallel with said thermionic valve to said direct current source, said anode means of said thermionic valve being connected to the positive potential of said direct-current source, said cathode means being connected to said anode of said discharge tube as well as to said cathode follower circuit, and said grid means being connected to said reference voltage source.

3. In an arrangement for counting and storing electrical pulses, the improvement described in claim 2 in which potentials derived from said reference voltage source are applied by way of unsymmetrical conductive elements to said grid means of said thermionic valve and are adapted to maintain automatically the potential at said grid means within a determined range or" values.

4. In an arrangement for counting and storing electrical pulses, the improvement described in claim 2, in which said reference voltage source includes a plurality of diodes in series and a voltage divider in parallel with said diodes.

5. Voltage stabilizing arrangements according to claim 2 wherein said grid means of said thermionic valve is coupled to said reference voltage source by at least two unsymmetrical conductive elements whereby a potential applied to said grid means is maintained automatically at a value within a determined range of values.

6. In an arrangement for counting and storing electrical pulses, comprising a gaseous electric discharge tube containing an anode and a plurality of cathodes, a direct-current source, the positive potential of which is applied to said anode, means for applying at least one pulse to one of said cathodes and storing the pulse within the discharge tube in the form of a discharge between said anode and last last named cathode, means whereby a pulse stored in said discharge tube in the form of a discharge is counted out from said tube in pulse form, and means for applying a varying number of pulses to a varying number of said cathodes in common and thereby causing a varying number of discharges to move from one group of said cathodes to another group of said cathodes, thereby varying the load in said discharge tube; the improvement of stabilizing means for maintaining automatically the value of the potential at said anode of said discharge tube stable within a determined range of values regardless of changes in the number of discharges in said discharge tube, said stabilizing means comprising a thermionic valve having anode m ans, cathode means and grid means therein, a cathode follower circuit associated with said thermionic valve and a reference voltage source connected in parallel with said thermionic valve to said direct current'source, said anode means of said thermionic valve being connected to the positive potential of said direct-current source, said cathode means being connected to said anode of said discharge tube as well as to said cathode follower circuit, and said grid means being connected to said reference voltage source.

References Cited in the file of this patent UNITED STATES PATENTS Philpott Feb. 14, 1938 Trevor July 6, 1943 Levy Jan. 27, 1948 Mentzer Oct. 3, 1950 Acton Sept. 1, 1953 Nelson Dec. 6, 1955

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