US2644111A - Electronic counter - Google Patents

Description

June 30, 1953 TENS TRANSFER OUTPUT J. R. DESCH 2,644,111

ELECTRONIC COUNTER Filed Dec. 4, 1951 INVENTOR JOSEPH R. DESCH HIS ATTORNEYS Patented June 30, 1953 ELECTRONIC COUNTER Joseph R. Desch, Dayton, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Application December 4, 1951, Serial No. 259,856

14 Claims.

This invention relates to a novel electron tube counting circuit and in particular to a circuit employing negative-grid thyratrons which are connected in a ring or chain for sequential operation one after another in response to input impulses.

The principal advantages of the novel circuit lie in its simplicity due to the elimination of many resistors and capacitors which had heretofore been required and in the consequent simplification in its fabrication.

In prior circuits using negative-grid thyratrons, it had been usual to have individual cathode resistors and bias supply and priming resistance networks for each of the tubes of the ring or chain, as well as individual input capacitors and capacitors in the extinguishing circuits for these tubes. The novel circuit does away entirely with bias supplying and priming resistance networks for the tubes of the ring or chain; does away with input capacitors and extinguishing capacitors for the tubes of the ring or chain; and reduces the number of cathode resistors which are required.

Briefly, the novel circuit utilizes negative-grid thyratrons of the tetrode type having at least an anode, a cathode, a control grid, and a shield grid. The tubes of the ring or chain are divided into two operational groups, with the cathodes of the tubes of each group connected together and to ground over a resistor which is common to the tubes of the group and with the anodes of each group connected together and over a resistor to a separate source of anode potential for each group.

The tubes are connected into an operative chain by floating connections between the tubes, which connections extend from, the shield grid of a tube of one group to the control grid of a tube of the other group. In case of a ring, the shield grid of the last tube in one group will be connected to the first tube in the other group. In the novel circuit, the shield grids serve as probe electrodes whereby the conducting condition of a tube can be utilized to control another tube. These floating connections cause the sequential operation of the tubes to take place in the desired order by enabling the shield grid or probe electrode in a conducting tube to so influence the control grid of the next tube in the sequence that the next tube will conduct when the next input impulse is received by the circuit.

The anode potentials for the two groups of tubes are derived from a potential control means which can be operated alternately to one or the other of two stable operating conditions. The anode 2 potentials are derived from the control means in such a manner that they can vary with the different operatin conditions of the means. When the control means is in one operating con-- dition, the anode potential which is supplied to one of said groups of tubes will be high enough to cause conduction in a tube of that group; but,

when the control means is in its other condition,

the anode potential which is supplied to this one group of tubes will have been reduced to a value which will not support conduction in the tubes of the group. In a similar manner, the anode potential which is supplied to the other group of tubes will be high or low, depending on the operating condition of the control means. The relation between the anode potentials which are supplied to the two groups of tubes is such that, whenever the high anode potential is supplied to one group of tubes, the low potential will be supplied to the other group of tubes.-

The input impulses for causing the step-bystep operation of the tubes of the chain or ring are applied to the control means, each impulse being effective to reverse the operating condition of the control means and thereby cause the abovenoted variation in the potentials supplied to the anodes of the tubes of both groups.

In the novel circuit, therefore, the combination of the grouping of the tubes and the variation of the anode potentials applied to the groups from the control means, together with the floating shield-grid-control-grid connections which connect the tubes in a chain or ring, enable the tubes of the chain or ring to be operated one at a time in sequence in response to input impulses which are applied to the control means.

If the tubes are connected in a ring and a plurality of rings are to be used for forming a mum-denominational order accumulator, suitable output-signal-generating means can be utilized as tens transfer means between adjacent orders to cause a unit to be entered in the higher order when the lower order exceeds its capacity.

Furthermore, if desired, controls can be supplied :for causing a particular tube to conduct to prepare the ring or chain for step-by-step operation.

It is an object of the invention, therefore, to protvide a simplified electron tube counting circu1 A further object of the invention is to provide a negative-grid. thyratron counting ring in which negative bias supp-1y and priming resistance networks can be eliminated, thereby requiring fewer impedance elements in the circuit.

A further object of the invention is to provide a novel negative-grid thyratron counting ring which has a simplified circuit and will be easier to construct.

With these and incidental objects in View, the invention includes certain novel features of construction and combinations of parts, a preferred form or embodiment of which is hereinafter described with reference tothe drawing which accompanies and forms a part of this specification.

Of the drawing:

Fig. l is a circuit diagram of one of thenovel counting rings which is capable of formingone denominational order of an accumulator, including provisions for presettingthe ring to -a.pre-- determined condition and also including provisions for controlling an output-signal-generating means which may be used to furnish tens transfer to a higher order of the accumulator.

Fig. 2 shows a modified form of trigger pair for supplying anode potentials to the ring.

Detailed description In order that the invention may be more clearly explained, it will be described as embodied in a counting ring which is suitable for use as a denominational order of a decimal accumulator. It is to be understood that the invention is not limited to its use as a counting ring. or to the use of ten tubes in the ring, because it is susceptible of use wherever sequential operation of tubes is desired and with diiferent numbers of tubes in the ring, the only limitation" being that, when connected to operate :as a ring, an even numberof tubes be provided. It will also become obvious from the following description that additional tubes can be included in the ring circuit without requiring any additional circuit elements of resistance or capacitance.

In the following description, values'of potential with reference to ground and values of resistance and capacitance, as well as tube types; will be given. It is not intended that the inven tion be limited to these particular potentials or to the values of resistance-specifiedherein, because the potentials used'are merely selected as convenient potentials for the disclosure; and the values of the circuit elements of resistance and capacitance given correspond in relative value to the potentials chosen. It is also obvious'that other types of tubes may be used and also-that other potentials may be used, and; when this occurs, the values of the circuit elements can be adjusted accordingly to maintain the properrelationship between the various parts "of the circuit. Throughout the drawing, the'heater' elements of the thyratrons are shown conventionally;

The type of tube usedthrough the circuit is the tetrode thyratron of the 2051'type, which'has' an anode, an indirectly-heated cathode, a control grid, and a shield grid;

Excellent results have been obtained from circuits constructed according to theinvention'and using'the values of resistance, capacitance, and, potentials to be given; These circuits also showed good tolerance to variations in'the positive potentialsupply and in the size of the input impulses which were supplied thereto..

The circuit of Fig. 1 includes aring o-f'digitrepresenting tubes, which tubes are operable step by step in sequenceya pair'of tubes 50" and 5|, which form the control means and operate as a. trigger pair and supply anode potentials to the. tubes'of the ring; a. pulse-shaping tube 52, upon which input impulses are impressed and from which a strong uniform operating impulse is sent to the trigger pair for each input impulse which it receives; and an output signal tube 53, which may be used for sending an impulse to another order each time the ring exceeds its capacity when the ring forms one order of an accumulator. In order to simplify the showing of the circuit, only the 0, 1, 2, 7, 8, and 9* digitrepresenting tubes of the'ring have been shown, because the circuits and the operation of the 3 to 6 digit-representing tubes are the same asthose shown and will be clear from those circuits which are shown.

The pulse-shaping tube 52, which is connected in a self-extinguishing circuit, will conduct momentarily and will be extinguished automatically each time an input impulse is applied thereto. The anode of this tube is connected over resistor 55, of 2'70 ohms, point 56, and resistor 51, of 1.5 megohms, to conductor 58, to which a potential of +150 volts is applied at terminal 59.

Point: 56in this circuit is connected to ground,

suitable to cause the pulse-shaping tube to con-- duct. Each time the tube 52conducts momentarily in response to an input impulse, the potential of point 60 will rise sharply to produce: a positive impulse, which impulses will be strong and uniform. These impulses are usedto drive the trigger pair of the control means from whichthe anode potentials for the tubes of the ring are derived.

The tubes 50 and 5| of the trigger pair of the control means are connected in similar. circuits, which enable the tubes to conduct alternately in response to positive potential impulses which are impressed thereon. The anodesof these'tubes are connected directly toconductor 58, which has +150 volts supplied thereto, and the cathodes of the tubesare connected to ground over resistors "Hi-and H, each of 20,400 ohms. The cathodes'of these tubes are also coupled b'y a blow-out circuit Containing a. resistor 12, of 7,800 ohms, and a capacitor 13, of .003 microfarad, in series. shield grid and the control grid of tube 50 are connected together and over point 14 and resistor 15-, of 250,000 ohms; to terminal 16, which supplies 12-volt bias potential. Similarly, tube 5| has its shield and control grids connected together and over point 71 and resistor 18, of 250,000 ohms, toterminal 16.

When tube 50 is non-conducting; its cathode, due to the high impedance of the tube, will be' at ground potential, but, when the tube' conducts, the potential of the cathode will rise sharply to about +135 volts, due to the division of the drops between the tube and resistor 10' in the cathode circuit. This means that point 79 inthe cathode circuit will make a similar excursion upwardly as the tube begins to conduct and downwardly as the tube ceases conduction. Similarly, point 80 in the cathode circuit for tube 5| will make a potential excursion upwardly and. downwardly as that tube begins .to. conduct and ceases to conduct.

Point 63 in this" circuit is The blow-out connection between; tubes 50 and 5! insures that only one tube of the. pair will be conducting at a time. -As positive impulses are impressed on the grids of the tubes, they will be ineifective on the .tube that is already conducting but will cause the non-con-. ducting tube to conduct. Conductionbeginning inthe previously non-conducting tube will .cause.

its cathode potential to rise sharply. This rise is sent as an impulse over thejblow-out circuit to the other tube to cause the previously 0011-.

sistor 85, of 100,000 ohms. Each input impulse which is applied to the pulse-shaping tube 52 will cause a positive impulse tobe sent overthis coupling to cause a reversal in the conducting condition of the tubes of thetrigger pair.

While the means in the control means which operates to one or another condition alternately in response to input impulses is shown as a gastube trigger pair, it is to be understood that the invention is not limited to the use of this particular form of means but can utilize any means which can operate to alternate conditions in response to impulses and can supply the necessary anode potential variations.

The connections involving the tubes of the ring are extremely simple and require very few circuit elements of resistance and capacitance.

These tubes are connected into two operational groups and are also connected for sequential operation. The anodes of the even digit-representing tubes to 8 are connected together and over a resistor 90, of 22,000 ohms, to point 19 in the cathode circuit of trigger tube 50, from which they will be supplied with a high potential which will permit conduction in a tube in the group when tube 50 conducts but from which they will be supplied a low potential which will not support conduction in a tube in the group when trigger tube 50 is not conducting. Similarly, the anodes of the odd digit-representing tubes 1 to 9 are connected together and over a resistor 9|, of 22,000 ohms, to point 80 in the cathode circuit of trigger tube and will be supplied with a high potential which will permit conduction in a tube in the group when trigger tube 5! conducts but will be supplied with a low potential which will not support conduction in a tube in the group when trigger tube 5| is not conducting.

Since only one tube of the trigger pair conducts at a time, only one of the groups of tubes of the ring at a time will be supplied with high potential.

The cathodes of the even digit-representing tubes are connected together and over point 92 and the common resistor 93, of 22,000 ohms, to ground. The connection of the cathode of the 0 digit-representing tube of the group to the point 92 is over point 94 and an additional resistor 95, of 33,000 ohms, which enables the oathode of the 0 tube to have a potential when the 0 tube conducts which is distinctive from that when any other even tube conducts. This distinction in potential is used to control theoperation of a transfer tube in a manner to-be explained more fully hereinafter. The cathodes of the odd digit-representing tubes are connected together and over the common resistor 96, of 22,000 ohms, to ground.

The connections between the tubes .of. the ring by which sequential operation-is obtained are extremely simple and extend from the shield grid or probe electrode of atube inone group directly to the control grid of thetubein the, other group which is next to be operated. As, an example, the shield grid or probe electrode of the 0 tube of the even group is directly connected to the control grid of the 1? tube of the odd group, and the shield grid or probe electrode of the 1 tube of the odd groupisdirectly connected to the control grid of the 2 tube of the even group, etc. The connection of the tubes in aring is completed by connecting the shield grid or probe electrode of the 9 tube to the control grid of the 0 tube. In the ring circuit as shown, the shieldv grid in a conducting tube will be more positive than the control grid, and this condition is utilized to obtaindirectional control in the sequential operation of the tubes and cause tube which has its control grid connected to a shield gridof a conducting tube to be fired before the tube which has its shieldgrid connected to the control grid of the conducting tube when highanode potential is supplied to the non-conducting, group ofv tubes. 7 I

It is to be particularly noted that, while the tubes of the ring are of the negative-grid .thyratron type, there are no negative bias supply and priming resistance networks provided for these tubes, the only connection to thecontrol grids of any of these tubes being the floating direct connection to the shielding grid orprobe electrode of the next preceding tube inv the ring; and that addition of tubes to the ring does not require the use of any more resistors or capacitors. I 1

Provision has been made for presetting the circuit to a starting condition, which in the instant embodiment will be that condition in which the 0 tube of the ring willgbe conducting. The circuit which connects the anodes of the even tubes has a switch I00 therein, which is nor mally closed but which can be opened in a pre: setting operation to prevent the application of anode potential to any of the evenf tubes exceptthe 0 tube. With the switch loll-open, the tri ger pair is operated to cause tube 50 to conduct. This supplies high anode potential to the 0 tube only, which will conduct, After the 0- tube has been rendered conducting, the switch I00 is closed to supply anode potential to the remaining even tubes, and the ring is ready for normal operation. With the 0 tube conducting, the drops across the anode resistor and the cathode resistors 93 and 95-will reduce the anode-cathode potential applied to theother even tube to a valuethat will prevent :initiation' of conduction in anyof theother feven tubes when theswitchlliflisclosed. I

Trigger'tubes 50 ,canJbe firedin the presetting operation by grounding itscontrol grid or by applying a positive impulse to/the. grid. l One meansfor applying positive potential to the grid is shown inFig. l and consists of; a capacitor 10!, of .01 microfarad, .which has '.:one "side grounded and which. has a lead-.102 connected tothe; other side. This le'adJllZ can. bestouched to the. conductor 58 to. charge {the capacitor llll and canrthen' beitouchede to point 103, whichzis' connected to the control gridsoftube50; to apply apositive impulse to this tube;

Any: suitable outputimeans canbe controlled Theioutput tube 53 hasits anode connected over point I05Land:resistor I06, of 1 megohm, t'oconductor 58, which has +150 volts applied thereto. Point I05-is connectedto ground over a capacitorv of .005 microfarad. The cathode is connected to ground Over point I! and resistor I08, of 68.000ohms, in parallel with capacitor I 09} of ;001 microfa'rad.'

Theishieldgrid and control grid of the output tube 53-are connected together and over a point H0; resistor: III; of 1- m'egohm, to the 9-volt--bias'supp1yterminal I I2. Point I I I0" in this: circuit is coupled over a capacitor I I 3; of l00 micr'o-microfarads, to an adjustable tap on a 1-megohma potentiometer II4, which is connected between ground and point 94 inthecathode circuitof' the-'O tube. Due to the resistor 95 in the cathode circuit and the coupling of point fl toground over the potentiometer I I4, point 94'-will-be-more'positive when the 0 tube conductsthanwh'en any of the other even tubes conduct; Thetap on the potentiometer is adjusted sothat the output tube 53wil1 conduct momentarily each time the 0' tube becomesconducting, but will not conduct'when' any of the other even tubes becomes conducting.

Eachtime the output tube 53 conducts, the potential of point I01 in its cathode circuit will rise, and this rise is transmitted over a suitable capacitor II as'an output impulse which can beusedtocause a unit value to be entered in the higher'or-der. A suitable switch can be include'din the outputcircuit, to be opened during presetting to prevent any undesirable output impulses-from being sent out during presetting as a result of firing the"0 tube.

It isto be understood that the output signal means which is disclosed herein is merely illustrative'andthat other forms which can beoperated'orxc'onditionedby' positive impulses can also be used with the novel ring;

Inathe circuitiof Fig, 1, the anode potentials for the two groups of tubes of the ring are derived'from the cathodesof the'tri'gger'pair, but the invention is not limited to this arrangement. In Fig. 2 is shown amodified-form of trigger- Dair in which anode potentials are derived from the anodes of the tubes of the pair; The trigger p'air of Fig; 2 can replace'the trigger pair which is-enclosed in the dot-and-dash outline'in Fig. 1, the:conne'ctions|a, b, c, d, e, and from the dot-' and-dash outline in both figures being the same; In the trigger pair of Fig. 2, the'tubes I and I 2| have .theiranodes connected over resistors I 22 and. I23, each of 20,400 ohms, and over connections (1 and b to the positive potential supply conductor (as 58 in-Fig. 1') and have their anodes coupledbya blow-out capacitor I24, of .01 microfarad; The cathodes of the tubes 7 are grounded, and their shield grids andcontrol grids are connected :together: and oven connections e 8 3 and ifztoi their. bias i supply and input couplings to the-:pulse-shaping tube (as52in Fig. 1).

The anode of .tube I20 is connected over resistor I25; of: 10,000? ohms; and connection it to the anodes ofxthe even digit-representing tubes of the ring; The anodes of this group of tubes of the ring will have a highpotential applied theretowhen tube I 20 is non-conducting and a low potential when tube I20 conducts. Similarly, the anode of tube lfl is connected'over resistor I26, of-10,00'0 ohms','.to the'anodes of the odd group of tubes of the ring and will supply a high potential to the tubes of this group when it is noncon'ductingand a low potential when it is conducting. When the trigger pair'of Fig. 2 is in-- corporated in thecircuit of-Fig'. 1 to replace the trigger" pairshown therein, a voltage of about +300 volts -is applied to terminal-59, and in-presetting the ring'to zero condition the right-handtube of -the triggerpair tube I2] is rendered con"- ducting. Otherwise the circuit constants and operation of'the circuitare'the same as when'the trigger pair of Fig; 1 is used in the circuit.

While'only' two forms of trigger pairs are shown as control means for supplying desired anode potentials to the groups oftubes of the ring, other" formsof trigger pairs also may be used; all that is required is thatthey be capable of furnish-- ing the necessary potential variations at two pointsin their circuit from which the potentials for thetwogroups of tubes can' be-derived.

Operation The operations will be explained with reference to 'thexcircuit of s Fig. 1'.

With. the variousoperating and bias potentials appliedand' with the-cathodes properly heated, the circuit may be set in its zero-condition by opening: switch I00 in the'anode circuit for the even group of tubes: and by touching the lead I02 first to conductor 58 and then to point I03 to fire tube 50 0f the trigger pair. As tube 50- conducts, its cathode;potential will be high; and thiszwill supply the high anode: potential to the 0 digit-representing} tube of the ring. After the "0 tube conducts; theswitch I00-is closed to supply anode potential'to the other tubes-of the even group. When the"0" tube is conducting, the drop-across-thetube-will bejust enough to sustain conductionbut will 1 not be high enough to initiate conduction in a. tube; hence, when switch I00 is closed after the0" tube is conducting, none of the other even tubes will begin to conduct;

When trigger tube 50 was fired, it caused. trig.- gertube -51 to be extinguished, if it were the first tube to. conduct when potential was supplied. With tube 5I'non-cond-ucting, it will supply low anode potential to all the odd tubes, and all of these tubeswill be non-conducting.

At the end of'the presetting. operation, the -"0 tube of 'the ring. and the triggertube 50' will'be conducting.

. It will be recalled that the digit-representing tubes are conhectedin a ring by floating direct connections between the shield grid or probe electrode'ofa tube in one groupv andthe control grid of atube in" theiother group. This means that the shield 'grid'or probeelectrodeof the 0'tube in theeven groupis connected to the control gridof "tlie'fT tube'in'the odd group; the shield grid or'prob'e electrodeof the 1 tube of the odd group "is 'con'nectedto the"2 tub'ein' the even" group? etc.

* When-"a tube-conducts: its shieldgridorprobe electrode, being in the ionized medium; will become more positive and will cause the control grid of the next tube in the ring, to which it is directly connected, to become more positive. Hence, with the tube conducting, the control grid of the 1 tube will be the only one connected to a Shield grid or probe electrode in a conducting'tube and will be more positive than the rest.

The first impulse from'the impulse source 67 will cause the pulse-shaping tube 52 to operate and send a strong positive impulse to the trigger pair to reverse its operating status. As tube 5! is fired and becomes conducting, its cathode potential will rise from the lowto the high value,

and during this rise the 1 tube will be rendered conducting first because its control grid was more positive than that of any of the other odd group tubes. As soon as the 1. tube begins to conduct,

the drop across resistors 9! and 96 will reducethe voltage across the tube sufliciently to prevent any other odd group tube from firing.v ",Only the 1 tube in the odd group will be conducting. The potential rise of the cathode of tube 5| is impressed across the blow-out capacitor 13 and the resistor "12 and'on the cathode of tube 59 to cause tube 56 to be extinguished in the wellknown manner. As tube 50 is extinguished, the potential of its cathode will drop from'its high value to its low value, and conduction can no longer be supported in the 0 tube, which will be extinguished.

The next input impulse on tube 52 will cause another reversal of the operating status of the trigger pair, and, since the'control grid of the 2 tube is more positive than'any of the other even group tubes, this tube will conduct. The reversal of the trigger pair wil1 apply the low potential to the odd group of tubes and will extinguish the 1 tube. 7 Additional impulses will cause the reversal of the trigger pair to bring about the step-by -step operation of the other tubes in the ring, the ?9 tube preparing the. 0 tube {or operation as the next tube of the sequence. With the operation of the 0 tube, the cycle starts all over again.

When the 0 tube conducts, its cathode potential rise is impressed on the grids of the tens transfer tube 53 to cause this tube to be fired and generate a tens transfer output impulse, which,

in operations other than presetting, can be impressed on suitable apparatus to cause an operation thereof.

While the circuits shown and described herein are admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the embodiments herein disclosed, for it is susceptible of embodiment in various other forms.

What is claimed is:

1. In a device of the class described, the combination of a first plurality of electron tubes; a second plurality of electron tubes; said tubes be ing 01' the negative-grid thyratron type, each having at least an anode, a cathode, a probe electrode, and a control electrode; a first common anode-cathode potential supply connected to the first plurality of tubes and forming them into a first operational group; a second common anodecathode potential supply connected to the second plurality of tubes and forming them into a second operational group; means to control said first and second potential supplies to provide a high anode potential to one group to cause conduction in a tube of that group and at the same time a from the probe electrode of a tube in one group to the control electrode of a tube in the other group; and input means for causing an operationoi the potential supply control means to reverse the high and low conditions of the anode potential supplied to the groups; the supplying oi anodecathode potentials in two groups and the varying of their anode potentials in response to impulses together with the serial connections between tubes, causing the tubes to be operated one at a time in sequence.

2. The device as claimed in claim 1 in which the connections to the control electrodes of the negative-grid thyratron tubes are floating connections and do not include any negative bias supply resistance network.

3. The device as claimed in claim 1 in which the connections connecting the tubes in the operational series are simply conductors and do not include impedance elements.

4. The device as claimed in claim 1 in which the anode-cathode supply for each group of tubes includes an anode resistance and a cathode resistance which are common to all the tubes or" the group.

5. The device as claimed in claim 1 in which the anode-cathode potential supply for each group includes'an anode resistance and a cathode resistance which are common to all the tubes of the group and in which the series connections between the tubes are direct connections which do not include any resistors or capacitors, whereby an extremely simple ring is provided.

fifThe'device as claimed in claim 1 in which the means for controlling the potential supplies is operable alternately to one or another of two stables states of operation and includes a potential supplying resistance network, said network in one of said states supplying high potential to the first group and low potential to the second group and in the other of said states supplying low potential to the first group and high potential to the second group.

'7. The device as claimed in claim 6 in which the means for controlling the potential supplies includes a trigger pair in said resistance network, said trigger pair being operable alternately to one and the other of said stable states in response to input impulses.

8. In a device of the class described, the combination of a plurality of digit-representing electron tubes of the negative-grid thyratron type, each tube having at least an anode, a cathode, a probe electrode, and a control grid; a common anode-cathode potential supply connected to all the odd digit-representing tubes and forming them into an operational group; a common anodecathode potential supply connected to all the even digit-representing tubes and forming them into an operational group; means to control the potential supplied by the two potential supplies to cause the potential at each supply to vary between a high anode potential which will cause a tube to conduct and a low anode potential which will prevent conduction in a tube and to further control the potential supplies so that when high potential is supplied to the even tubes, low potential will be supplied totthe odd tubes, and vice versa, said control means operable inuresponse to impulsesand upon eachoperation reversing the high and low anodepotentials supplied to the odd and evenflgroups1of-tubes; means connecting the tubes in digital :sequence, each connection being agfioating connectionand extending directly from the probe'elect-rode of a tube to the control-gridof the-tube of next higher digital value and eliminating any negative bias supply for the control grid; and-meansto apply input impulses to the potential supply control means to cause its operation to vary-the potentials supplied to the ;ring, whereby to cause the sequential operation of the tubes '0f';the ring.

9. The device as claimed in claim 87in which an anode resistor and a ;.cathode resistor are included in theanode-cathode potential supply of each group and are common to the tubes ;of the group; and in which the connections for connecting the tubes in the-digitalsequence are only conductors, whereby a ring requiring-a minimum of resistors is produced.

10. The device as claimed in claim'8-in which the means to control the potential supplies is a trigger pair having two stable states of operation and operable alternately to one and the other of the two states and including a potential, supplying resistance network for supplying high potential to the odd groupof tubes and low potentialto the even group of tubes when the trigger pair is in one of its operating states and for supplying low potential to the odd group and high potential to the "even group when thetrigger pair is in the other of its operating states.

11. In a device of the class described, the combination of a plurality oftubesof the negativegrid thyratron type, each tube including at least an anode, a cathode, a probe electrode, and a control grid; a circuit connecting the cathodes of half of the tubes together and over a common impedance to a cathode potential supply to form a first group of tubes; a circuit connecting the cathodes of the other half of the tubes together and over a common impedance to'a cathode potential supply to form a second group of tubes; a circuit connecting the anodes of the first group of tubes together and over-a common impedance to a first source of'anode potential; a circuitcon- 12 meeting the anodes of thesecondgroup of tubes together andover acommon impedanceto asec- 0nd source of anode potential; meansto control an operational series using tubesfromthe first and second groups alternately in the series, :the series connections being floating, negative-biasfree connections extending directly vfrom jthe probeelectrode of a tube to the controlgrid of the next tube in the series; and means for-applying input impulses to the anode potentialcontrol means to cause it to operate to reverse the high and low potential supplies each time an impulse is received, said reversal of potential conditions together with the series connections, causing the sequential step-by-step operation of the tubes in the ring; said anode circuits and cathode circuits with their common impedances, together'with the direct series connections between tubes, enabling a ring to be produced with a minimum of impedance elements.

12. The device as claimed in claim 11 in which the series connection between tubes is merely a conductor and contains no resistors.

13. The device as claimed in claim 11 in which the means for controlling the potential at two potential sources is operable alternately to one.

or another of two conditions in response to input impulses, said means in one condition causing the high potential to be applied to the first group and low potential to be applied to the second group and to reverse the high and low potentials when in said'other condition.

14. The device as claimed in claim 13 in-which the means which is operable to one or another of two conditions is a-trigger pair which includes a resistance network which is controlled to supply the potential variations.

JOSEPH R. DESCH.

No references cited.

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