US2310105A

US2310105A - Counter circuit

Info

Publication number: US2310105A
Application number: US388820A
Authority: US
Inventors: Philip C Michel
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1941-04-16
Filing date: 1941-04-16
Publication date: 1943-02-02
Anticipated expiration: 1960-02-02

Description

Feb. 2, 1943. P; c. MICHEL 2,310,105

COUNTER CIRCUIT Filed April 16, 1941 2 Sheets-Sheet 1 OUTPUT F iig-ZA.

|23456789l0ll FlcgZB.

OUTPUT i P-DEPENDS ONLY ON c. Rg ANDRm.

isa- '1' 2 I a 4 (5 56:6 6 o--- l oB+ 1-1 Q 9 v' 0 L I SCALE 0F I0 SCALE 0F 5 SCALE OF 2 IMPULSE IMPULSE IMPULSE COUNTER COUNTER COUNTER AND DIVIDER AND DIVIDER AND DIVIDER Inventor: Philip c. Michel,

by I I mttorney Feb. 2, 1943.

P. C. MICHEL COUNTER CIRCUIT Filed April 16, 1941 2 Sheets-Sheet 2 Pi g. 4.

Inventor: Philip QMichel,

b )wwy His Atborney.

Patented Feb. 2, 1943 New York Philip G. Mi'clie Schenectady, -.General Electricz' companmi Application April 16, 1941, Serial No. 388,820

9 Claims.

My invention relates to circuits for discharge devices and concerns particularly counting and timing arrangements.

It is an object of my invention to provide an improved electrical impulse counter and frequency divider, as well as either a frequency indicator or timer.

A further object of my invention is to provide such arrangements, which operate independently oi the time interval between impulses down to a lower limit fixed by the characteristics of discharge devices available, and which is adapted to cascading in stages and to variation of the scale or dividing factor for each stage.

In carrying out my invention in its preferred form I provide a plurality of electric discharge devices having anodes, cathodes, and control electrodes so connected as to form a series circuit when all of the discharge devices are conducting and having separate cathode resistors to ground. Suitable couplings between cathodes are provided to prevent series firing of all the tubes when an input signal is applied to the control electrodes, whereby one tube is ignited at a time, the first discharge device and its anode circuits being supplied by a source of anode voltage and each succeeding discharge device having the anode supplied by the voltage across the cathode resistor of the preceding discharge device. In this way the first impulse fires or ignites the first tube and raises the voltage across its cathode resistor sufiiciently to ignite the second tube when the next impulse is received. Successive impulses ignite additional tubes so that the number of impulses whichhave been received is indicated by determining the number of discharge devices which are conducting. A connection is provided between the last discharge device and the first to extinguish the discharge in all of the devices when the last discharge device becomes conducting. A connection taken from the circuit of the last discharge device may be utilized to supply impulses to a second stage in which the number of impulses received is a fraction of the impulses supplied to the preceding stage. The dividing factor of each stage is determined by the number of discharge devices in the stage.

A better understanding of the invention will be afi'orded by the following detailed description considered in connection with the accompanying drawings, in which Fig. 1 is a circuit diagram of a counter circuit having a scale of 5 which may be employed as one stage of'a multistage counter system; Figs. 2A and 2B are graphs representing the input and output voltages of the circuit represented in Fig. 1; Fig. 3 is a schematic diagram representing a cascading arrangement; Fig. 4 is a circuit diagram illustrating a modification of Fig. 1 using a vacuum type extinguishing tube; and Fig. 5 is a modification of Fig. 4 for a scale of 2. Those features of my invention which are believed to be novel and patentable are pointed out in the claims appended hereto.

In Fig. 1 there is illustrated a counter circuit which may be utilized independently as a counter for counting the remainder of any number of impulses divided by 5, and as a frequency divider for producing impulses one-fifth as great in number as the input impulses, or which may serve if desired as an intermediate stage I 0 of a multistage system represented diagrammatically in Fig. 3. There is provided an input terminal Ii with a neutral terminal H, which may be grounded, so that an input voltage signal may be applied between the terminals II and i2. There is an output terminal l3 and the output signal appears as a voltage between the terminals l2 and It. A plurality of discharge devices T1, T2. T3, T4, and T5 is provided having electrodes designated by letter symbols with appropriate subscripts corresponding to those of as vapor electric discharge tubes, ionic discharge tubes, and Thyratrons. However, I shall employ the term "gaseous discharge tube and "gaseous discharge device throughout the description and claims to refer to discharge devices of the type having the characteristics mentioned, regardless of their actual construction.

A source of anode voltage is provided and may be connected between the terminal 3+ and the ground terminal l2. A plurality of current-conducting cathode impedances such as resistors R1a, Rn, Rm, R19, and R15 is connected in the'cathodeto-ground circuits of the discharge tubes T1, T2,

- T3, T4, and T5 respectively. The tubes also have connections from the cathode of one to the anode of the next. so that they may be considered as connected in series between the anode source 3+ and the ground terminal l2. Bubstantially non-conductive coupling devices such as condensers Ci, Ca, Ca, 04, and Cs are connected between the input signal terminal ii and the control electrodes 001 to CG; of the tubes T1 to T5.

The source of negative biasing voltage is connected between the bias terminal C- and the ground terminal II. For connecting the negative bias terminal to the control electrodes a plurality of relatively low-conductance connections such as resistors R1-Rs of the order. of a megohm is provided. In order to prevent the eifective bias potential of the control electrodes from falling too far below the cathode potentials and injuring the discharge tubes, voltage divider circuits are preferably provided formed by connecting resistors Rs-Rm between the control electrodes and cathodes of the tubes Tl-Td respectively, the resistors RsR1o having smaller resistances thanthe resistors R1Rs and the voltage dividers being formed by the series connections of the resistors. In the case of TI. the voltage divided consists of the resistors Bi and Rs in series.

The arrangement is such that a discharge as initiated in tube Ti, which may be referred to as the initiating tube and the discharge is extinguished by the action of the tube To, which may be referred to as the extinguishing tube. The remaining devices Ta, '1: and T4 may be increased or reduced in number or may be omitted entirely according to the division factor desired between input and output signals, and these tubes if employed are referred to as intermediate tubes. Coupling condensers Ca. Ca, and Cs are provided between the cathodes of the intermediate tubes T2, T3, and T4 and the cathodes of the preceding tubes. Resistors R11, R1: and R1: are included in the respective connections. The extinguishing tube T5 has its anode A5 connected to the cathode K4 of the tube T4 by means of a resistor R14 and a condenser Co is connected between the anode A5 and ground. The time constant of the circuit R14, C9 is made large enough so that, when the tube T4 ignites. the rise of the anode potential of the extinguishing tube Ts to the ignition level will be delayed until the control electrode CGs has dropped sumciently negative to hold of! conduction of the tube To.

The condensers Cs, C1 and Ca in the connections between the cathodes of the intermediate tubes and the preceding tubes have sufllcient capacity to raise the cathode potential of a tube with its anode potential when the preceding tube fires in order to prevent firing of both tubes. For example, the capacity of the condenser Cs is sufllciently large and the resistance of the resistor R11 is suiliciently small in relation to the resistance of the resistor Rn, so that the potential of the cathode K: rises when the potential of anode A1 is raised by the passage of current through the cathode resistor Ru: and the potential of the cathode K: remains high until the input signal disappears, whereby the potential difierencebetween the electrodes A: and K: remains less than required to maintain an arc until the control electrode CG: is no longer at positive potential. The resistors R11, R1: and R1: in the connections between the cathodeshave such resistances as to. limit the anode currents in the intermediate discharge devices during discharge thereof and to permit gradual dissipation of the energy stored in each of the condensers Cs. C1 and Cs when the corresponding discharge tube ignites. For example, after a suflicient time delay the condenser Cs becomes charged, the potential existing across the cathode resistor Rm. Then when the tube I: is ignited by the second input impulse, the resistor Ru limits to a, safe value the current discharging the condenser Cs through the tube T2.

For extinguishing the discharge in the initiating tube Tl when the extinguishing tube To is ignited, a relatively large condenser C10 is connected between the cathode of the extinguishing tube To and the cathode of the initiating tube T1. The time constant of the circuit C10, R15 is made small enough so that the charging of the condenser Cm (initiated by the firing of the tube Tl) will not hold the cathode of the extinguishing tube To positive ior such a long time as to prevent firing .on.each fifth impulse at the highest input pulse frequency to be used. The time constant of the circuit of the condenser C9 discharging through To into R15 and through the condenser Cm into'theresistor R16 effectively shunted by R17, Rn, Rio, and Rn is made large enough, however; to hold the oathode Kl of the initiating tube Tl positive until the initiating tube T1 is deionized, and its control grid has fallen fromthe fifth impulse to a potential which prevents recurrence of conduction on that impulse.

The-anode As Of the extinguishing tube T5 may be employed as the output terminal if the circuit into which the output feeds is not such asto react objectionably upon the counter circuit and if an output impulse of reversed polarity is acceptable. However, I consider it advantageous to provide an isolating and coupling circuit which reverses the polarity from that of the anode A5 to provide amplified output impulses of the same polarity as the input. The coupling circuit for the output may take the form of a discharge device Ts with an anode As, a control electrode or grid Go and a cathode Ks. A coupling condenser Cu may be connected between the anode A5 and the control grid Gs with a resistor R20 interposed, and a gridleak resistor R21 may be connected between the control electrode and the cathode. If the coupling circuit is,.to serve also as a polarity reversing circuit, an anode resistor R2: is advantageously connected between the voltage source terminal 3+ and the anode As and the tube Ts is advantageously of the continuous control or vacuum type, sometimes called a hard tube. For restoring all of the tubes to the non-conducting condition a reset switch It may be connected between the anode voltage source 3+ and the anode A1 of the initiating tube T1.

For conveniently indicating which of the tubes is the last to become conducting, voltage responsive indicators, preferably of the zero or low current drain type such as neon discharge tubes, are connected between the anodes and cathodes of the tubes T1Ts, and they carry the

scale numerals

0,1, 2, 3, and 4, respectively, to indicate the number of impulses received in a manner which will be explained hereinafter.

It will be understood that if discharge devices of the indirectly heated cathode type are employed, a suitable source of heater current. not shown, is provided, and this source may be held and flowing at a positive potential by means oi a tap on a voltage divider, not shown, connected across the anode voltage source to prevent excessive potential diflerence between the heaters and the cathodes.

The manner in which the

indicators

0, 1, 2, 3, and 4 indicate the number of impulses which have been received will be apparent from a consideration of the manner of operation of the circuit. Before any impulses have been received and when none of the tubes are conducting, the full voltage of the Hide source 3+ t ground appears across the anode and cathode of the initiating tube T1. Consequently, voltage also appears across the zero-indicating device 0, The fact that this device is energized or lighted indicates that the count thus far is zero. The other indicators i, 2, 3, and l are dark for the reason that these remaining tubes obtain their voltage from the potential drop across the first cathode resistor Rm which at this'time carries no current and therefore has a zero potential drop. When the first impulse is applied to the input terminal ll the control electrodes of all five discharge tubes are driven positive to overcome the negative bias of the source C-. Accordingly, the initiating tube T1 becomes conducting. The other tubes do not become conducting, however, because they have no anode voltage applied. As current begins to flow in the cathode resistor R16 it raises the potential of the anode A2 of the first intermediate tube T2 but the capacitative coupling Ce causes the potential of the cathode K2 to rise with that of the anode A2, thus preventing ignition of the first intermediate tube T2. Since the input impulses are of short time duration, the positive voltage impulse applied to the. control electrode CG: will have disappeared before the potential of the cathode K: has fallen sufficiently below that of the anode A2 for ignition of T2. The rate at which the potential of the cathode K: falls to zero is determined by the time required for the condenser Co to charge through the resistors R11 and R17. Potential appearing between A2 and K: causes the indicator i to light, and at the same time the reduction of potential between A1 and K1, due to conduction of T1, extinguishes the indicator 0.

When the next input signal is received the control electrodes are again driven positive and this time the first intermediate tube T1 ignites because its anode is energized by the voltage across the resistor Rm. The ,condenser Ca thereupon discharges through the tube T2 but the discharging current is limited by the resistor R11 to pro-= tect the tube. Since the tubes T1 and T2 are now both conducting the indicating devices and i are both shunted so that they do not l ghtup. Voltage. appears, however, across the indicating device 2 connected. across the tube Ta sincethere is now a voltage drop across the cathode resistor R11. Ignition at this time of the tube T3 was prevented by the coupling C1 in the same manner as previously discussed.

Subsequent impulses will ignite the additional tubes one at a time. Each time the number of.

impulsesreceived will be indicated by which one of the indicating devices 04 is energized, all but one of these being deenergized for the reasons explained. When the fourth impulse is received the voltage across the cathode resistor R1 rises as in the previous case. However, the extinguishing tube T5 is prevented from firing by reason of the time delay required for the condenser Cu to be charged suiiiciently to raise the anode potential extinguishing tube Ts becomes conducting and the potential rises across the cathode resistor R15. The relatively high capacity connection between the cathode K5 and the cathode K1 momentarily raises the'potential of the cathode K1 above that of the anode T1 so as to extinguish the discharge in the initiating tube T1. Before the condensers Co and 010 have discharged to lower the cathode potential of the initiating tube T1, that tube has become deionized so that current therein ceases and the voltage drop across the resistor R16 falls to zero. The ignition of the remaining tubes Tar-T5 has thereby also been extinguished. The circuit is thus restored to its initial condition and the same action may be repeated indefinitely. After any number of impulses the indication last produced will beretained if no further impulses are received, because the circuit is stable and does not depend upon the retention of charge by a condenser.

It will be understood that my invention is not limited to the use of circuit elements having speciflc numerical values of constants nor to the use of particular classes of electric discharge devices. I have found, however, that satisfactory results may be obtained by employing gas tetrodes of the construction designated as 2051 for the gaseous discharge devices T1 to T5, by employing a vacuum type triode consisting of half a-tube known by the designation 6N7 to form the coupling discharge device Te and by using numerical values of circuit constants indicated in the following tabulation:

C1-C5 micromicrofarads 40 Cc-Cs microfarad .006 C9 do .02 Clo .05 C11 micromicrofarads 20 R1-R5 megohms 2 Rc-=Rio 0.5 R1iR1: ms 1,000 R14 do 10,000 Rue-R19 fin 50,000 R20 megohms 0.5 R21. o 0.15 Rn ohms 15,000 3+ volts 300 C do The indicators 0 to 0 may be neon tattelites with one-half megohm series resistors.

Utilizing the tube classifications as specified,

* when using input voltage signals of 20 volts or more, the input sine] wave may be represented by the graph of Fig. 2A where the duration of the positive signal impulses may be microseconds or less. The interval between input impulses may be any value greater than 500 microseconds. The limiting'yalues depend of course upon the tube characteristics. Employing five tubes in order to obtain a scale of five as shown in Fig. l. the output voltage signal is represented by Fig. 23, where the voltage is approximately volts with the circuit constants specified. The duration of the output signal impulse depends only upon the magnitudes of the elements in the coupling circuit. viz: the condenser Cu and resistors R20 and R21.

As already mentioned. the number of intermediate, tubes T2 and T4 may be changed. or they may be eliminated entirely in order to change the division factor between the number of input and output signals. For example, if the intermediate tube Ta is removed together with all of the apparatus within the dotted rectangle IS, the number of output impulses will be one-fourth the number of input impulses. If all three tubes T2, T3 and T4 are omitted, together with the other elements corresponding to those within the dotted rectangle IS, the scaleof-two counter is formed having an initiating tube T1. and the extinguishing tube T5. 11' a decimal'system of counting is desired, five additional tubes may be added to the circuit of Fig. 1 to form a. scale-of-IO counter and divider. Alternatively, the circuit shown may be cascaded with a scale-of-two impulse counter or divider to produce a division by 10. Any number of such circuits may be cascaded as desired or the impulse counter Ill may be cascaded with impulse counters and dividers of other electrical or mechanical types according to the anticipated frequency in each stage of the counting system, each'stage eflecting a division according'to its scale.

I have referred to my circuit particularly in connection with its use as a counter of impulses or as a divider of the frequency or the number of impulses. However, the circuit may be employed as a timer if the input signals are supplied from a constant frequency source, or the circuit may be used as a frequency me'ter if the impulses are supplied for a fixedtime duration.

In the arrangement illustrated in Fig. 1, premature ignition of the intermediate tubes is prevented by condensers Ca, 01, and Ca which are each connected between the cathode of an intermediate tube and the cathode of the preceding' tube. Premature ignition of the extinguishing tube Ts when the preceding tube ignites is prevented, however. by a condenser between the anode of the extinguishing tube and the ground connection l2 with the resistor R14 interposed in the anode lead of the nextinguishing tube Ts.

My invention is not limited, however, to having only the extinguishing tube connected in this manner for prevention of premature ignition. The arrangement illustrated has the advantage, nevertheless, that there is less condenser energy to'be dissipated when the extinguishing tube Ts becomes conducting for the reason that the condensers Co, Cr, and Cs are discharged before the tube Ts becomes conducting.

Although I have illustrated and described a counter or divider circuit in which the last stage tube, that is, the extinguishing tube T5 is of the gaseous type, it is to be understood that my invention is not limited to the precise arrangement thus far described. Since the extinguishing tube '1; is not required to remain conducting after the voltage impulse which fires it disappears. it is not necessary that the extinguishing tube be of the gaseous or ionic discharge type. A socalled hard tube or vacuum tube may also be employed.

If desired, the extinguishing tube may take the form of a four-element vacuum discharge device having a second grid or positive electrode referred to as a screen grid, as illustrated in Fig. 4. In Fig. 4 the gaseous discharge device Ts is replaced by a vacuum tube l'l having an anode it directly connected to the anode voltage source 13+ and having three other electrodes connected as a triode in the same manner as the anode, control electrode and cathode of the gaseous discharge tube shown in Fig. 1. The

vacuum tube "may be of the type designated as 6L6 for example. The vacuum tube II has a screen grid is which may be considered either as a second control electrode or a second positive electrode, corresponding to the anode of a triode and the positive electrode [9 is connected through the resistor R14 to the cathode of the preceding tube as in Fig. 1. The vacuum tube I! has also acontrol electrode CGs and a cathode Ks corresponding to the electrodes bearing the same reference numerals in Fig. 1. It will be understood that the negative bias applied to the control electrode CG: of the'tube I'I should be so chosen as to give the best results with this type of tube and the relative magnitudes of the potentiometer resistors R5 and Rm are so chosen as to give the desired negative bias. To simplify the drawing, some of the intermediate stages scale-of-three counter.

have been omitted in Fig. 4 and are indicated simply by the dotted rectangle 20. If these are omitted, the arrangement of Fig.4 becomes a In considering the electrodes is, CGs and Ks as a triode, the operation of the circuit of Fig.

4 is the same as that of Fig. 1. When the first positive voltage impulse is applied to the input electrode II, the initiating tube T1, a gaseous tube is fired. This operation short-circuits the neon tube I, causing the light to go out and the voltage drop across the cathode resistor Ru applies voltage to the anode A2 of the intermediate tube T: and also applies voltage to the neon tube I. The neon tube l is thus illuminated to indicate that the first impulse has been received. On the application of a second voltage impulse to the input terminal II, the intermediate tube T: fires and voltage'appears across the resistor Rn. Assuming the additional stages 2| have been omitted, the voltage is then applied through the resistor, R14 to the screen grid I! of the vacuum tube l1 and to the neon tube which-is connected between the screen grid and the cathode of the vacuum tube IT. The vacuum tube It is prevented from firing, however. by reason of the time delay produced by the connection of the condenser Ca between the screen grid l9 and the terminal II. This holds the screen grid I! at a sufiiciently low potential momentarily to prevent a discharge in the tube ll until the impulse applied to the terminal II has fallen to zero. Gradually the potential of the screen grid it rises to the value of the voltage drop across the cathode resistor of the preceding tube and thus the vacuum tube I! is primed for operation upon reception of the next impulse applied to the input terminal I I. when the next impulse is received it raises the potential of the control electrode CG; and causes the tube I I to fire. The

screen grid l9 carries relatively little current and serves to discharge the time delay condenser C5. However, the anode l8 suppliesthe principal portion of the discharge current which flows through the cathode resistor R15, causing a sudden rise in the potential of the cathode K5. This potential is transmitted to the cathode K1 of the initiating tube through the condenser C10, and the initiating tube T1 is extinguished in the samemanner as explained in connection with Fig. 1.

The circuit. of Fig. 4 may be converted to a scale-of-two-counter in the same manner as the circuit of Fig. 1 by omitting also the intermediate tube T: with its associated circuit elements CI,'R11, R11, neon tube I, coupling condenser C2. potentiometer resistors R1 and R2. The resistor R14 will then be connected directly between the triode portion of the tube I'I, that is, to the screen grid l9.

However, the use of a hard tube for the screen grid for the extinguishing function permits a further simplification in the case of a scale-oftwo-counter. As illustrated in Fig. the time delay elements R14 and C may be omitted in the simplified arrangement illustrated in Fig. 5. Since the screen grid I9 is not required to supply appreciable current for the discharge of the tube il, a condenser such as the condenser Co is not required between the screen grid I9 and the ground connection for supplying energy to produce a strong discharge in'the vacuum tube II. The energy in this case comes from the anode voltage source B+ which is connected to the anode l8. There is also no need for the elements R14 and Co to introduce time delay in the application voltage to the screen grid I9 when the tube T1 fires because the condenser C connected between the cathodes of the two tubes causes the potential of the cathode K5 of the tube i! to rise momentarily when the initiating tube T1 fires, thus preventing sufilcient potential diiference between the screen grid I9 and the cathode K5 to permit premature ignition of the tube ii.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What Iclaim as new and desire to secure by Letters Patent of the United States is:

1. A counter circuit comprising a. plurality of gaseous discharge devices including an initiating discharge device, an extinguishing discharge device, and one or more intermediate discharge devices, each discharge device having an anode, a cathode and a control electrode, an input terminal adapted to have electrical impulses to be counted applied thereto, a ground terminal, an output terminal, an anode voltage source terminal, a negative bias voltage source terminal, a plurality of low-current-drain indicators equal in number to the said gaseous discharge devices each connected between the anode and the cathode of one of said discharge devices, a plurality of cathode resistors each connected between one of said cathodesand said ground terminal, substantially non-conductive couplings between said input terminal and said control electrodes, low conducttance connections between said bias voltage terminal and said control electrodes, 2. connection between said anode voltage terminal and the anode of said initiating discharge device, a plurality of connections each between the cathode of onedischarge device and the anode of the next whereby all of the discharge devices are connected in series, the initiating discharge device being the first and the extinguishing discharge device being the last in the series, a resistor being included in the connection between the anode of the extinguishing discharge device and the'cathode of the preceding discharge device, a plurality of connections each including resistance and capacitance in series between the cathode of each intermediate discharge device and the cathode of the preceding discharge device in the series, a relatively large condenser connected between the cathodes of the initiating and extinguishing dis charge devices and a voltage-reversing coupling circuit having .an input side connected between the anode of the extinguishing discharge device and the ground terminal and having an output side connected between the said output terminal and ground, whereby the anode-cathode circuit of the initiating discharge device is energized from said anode voltage supply terminal and each of the other discharge devices is energized by the voltage across the cathode resistor of the preceding discharge device in the series, and each electrical impulse applied to the input terminal fires the first discharge device in the series which is not already conducting until the extinguishing discharge device is caused to become conducting whereupon all of the discharge devices are extinguished, each of said indicating devices thus being energized only when the discharge device 1 across which it is connected has voltage applied to the anode butis not conducting so that the number of impulses is indicated by which one of the indicating devices is energized.

2. A counter circuit comprising a plurality of gaseous discharge devices, each discharge device having an anode, a cathode and a control elecbias voltage terminal and said control electrodes,

a connection between said anode voltage terminal and the anode of the first of said discharge devices, connecting means between the cathode of any discharge device and the anode of the next whereby the discharge devices are connected in series, a resistor being included in the connecting means between the anode of the last discharge device and the cathode of the preceding discharge device, a. condenser connected between the anode of said last discharge device and said ground terminal, substantially non-conductive coupling means between the cathode of each discharge device and the cathode of the discharge device following it including such coupling means between the last discharge device and the first, but excluding such coupling means between the last discharge device and the one preceding it other than the first, whereby the anode-cathode circuit of the first discharge device is energized from said anode voltage supply terminal and any other discharge device is energized by the voltage across the cathode resistor of the preceding discharge device in the series and each electrical impulse applied to the input terminal fires the first discharge device in the series which is not already conducting until the last discharge device is caused to become conducting whereupon the entire series of discharge devices is extinguished.

3. A counter circuit comprising a plurality of gaseous discharge devices including an initiating discharge device, an extinguishing discharge device and one or more intermediate discharge devices, each discharge device having an anode, a cathode and a control electrode, an input terminal adapted to have electrical impulses to be counted applied thereto, a ground terminal, an anode voltage source terminal, means for biasing the control electrodes of said discharge devices to non-conductive condition, a plurality of voltage responsive indicators each connected between the anode and the cathode of one of the discharge devices, a plurality oi cathode resistors each connected between one of said cathodes and said ground terminal, substantially nonconductive couplings between said input terminal and said control electrodes, a connection between said anode voltage terminal and'said initiating discharge device, a plurality of connections each between the cathode of one discharge device and the anode of the next whereby all of the discharge devices are connected in series, the initiating discharge device being the first and the extinguishing discharge device being the last in the series, means interposed between the circuit 01' each discharge device and the following one to maintain the potential diflerence between the anode and cathode of the following discharge device substantially unchanged momentarily, means interposed between the circuit of the extinguishing discharge device and the initiating discharge deviceto cause a change in potential in the same direction to take place momentarily in the cathodes or both said discharge devices when the extinguishing discharge device becomes conducting, whereby the anodecathode circuit of the initiating discharge device is energized from said voltage supply terminal and each of the other discharge devices is energized by the voltage across the cathode resistor 01' the preceding discharge device in the series, and each electrical impulse applied to the input terminal fires the first discharge device in the series which is not already conducting until the extinguishing discharge device is caused to become conducting whereupon all of the discharge devices are extinguished, each of said indicating devices thus being energized only when the discharge device across which it is connected has voltage appliedto the anode but is not conducting so that the number of impulses is indicated by which one 01' the indicating devices is energized.

4. A counter circuit comprising a pair of gaseous discharge devices referred to as an initiating discharge device and an extinguishing discharge device, each discharge device having an anode, a cathode and a control electrode, an input terminal adapted to have electrical impulses to be counted applied thereto, a ground terminal, an output terminal operatively connected to the anode of the extinguishing discharg device,'an

- anode voltage source terminal, a negative bias voltage source terminal, a pair or cathode resistors each connected between one of said cathodes and said ground terminal, substantially nonconducting couplings between said input terminaland said control electrodes. low conductance connections between said bias voltage terminal and said control electrodes, a connection between said anode voltage terminal and the anode of said initiating discharge device. a re- I sistor connected between the cathode of the initiating discharge device and the anode of the extinguishing discharge device whereby the discharge devices are connected in series, a relatively large condenser between the cathodes oi the initiating and extinguishing discharge devices and a time delay condenser connected between the anode of the extinguishing discharge device and the ground terminal, whereby the anode cathode circuit of the initiating discharge device is energized from said anode voltage supply terminal and the extinguishing discharge device is energized by the voltage across the cathode resistor or the initiating discharge device and sucthe ignition oi the extinguishing discharge device simultaneously raising the cathode potential 01' the initiating discharge device by the capacitive coupling between cathodes to extinguish the discharge in both devices.

5. A counter or divider comprising a plurality of gaseous discharge devices and having an anode, a cathode and a control electrode, an input terminal adapted to have electrical impulses to be counted applied thereto, a ground terminal. an anode voltage source potential, means for holding the control electrode potential sufiiciently low for normally preventing ignition of the discharge devices, a plurality of current conducting cathode impedances each connected between one of said cathodes and said ground terminal, coupling elements for maintaining the potential diflerence between anode and cathode of any discharge device substantially unchanged momentarily during ignition oi the preceding discharge device, a connection between said anode voltage terminal and the anode oi the first or said discharge devices, connecting means between the cathodeof any discharge device and the anode of the next for connecting the discharge devices in series, and means for momentarily fixing the potential diflerence between the cathodes oi. the first and last discharge devices during ignition or the last discharge device, whereby the anode-cathode circuit of the first discharge device is energized from the anode voltage supply terminal and any other discharge device is energized by the voltage across the cathode impedance of the preceding discharge device in the series and each electrical impulse fires the first discharge device in the series which is not already conducting until the last discharge device is caused to become conducting and to raise the cathode potential of the first discharge device for extinguishing all of the discharge devices.

6:A counter or divider circuit comprising a sly low for normally preventing current conduction by the discharge devices, a plurality of current-conducting cathode impedances each connected between one of said cathodes and said ground terminal, coupling elements for maintaining the potential difierence between the positive electrode and the cathode of any discharge device substantially unchanged momentarily during ignition of the preceding discharge device, a connection between said positive electrode voltage source terminal and the positive electrode 01 the first of said discharge devices, connecting means between the cathode of any discharge device and the positive electrode of the next i'or connecting the discharge devices in series, with the said extinguishing discharge devices being the last in the series, and means for momentarily fixing the potential difierence between the cathode oi the extinguishing discharge device and the first discharge device in the series during ignition of the extinguishing discharge device whereby the positive electrode to cathode circuit of the first discharge device is energized from the positive electrode voltage supply terminal and any other discharge device has voltage supplied by the potential difference in the cathode impedance of the preceding discharge device in the series, and each input impulse fires the first discharge device in the series which is not already conducting until the extinguishing discharge device is caused to become conducting to raise the cathode potential of the first discharge device for extinguishing all of the discharge devices.

'7. A circuit comprising an initiating discharge device of the gaseous discharge type and an extinguishing discharge device, each'discharge device having a positive electrode, a cathode and a control electrode, an input terminal adapted to have electrical impulses to be counted applied thereto, a ground terminal, a positive electrode voltage source terminal, means for holding the control electrode potentials sufiiciently low for normally preventing current conduction by the discharge devices, couplings between said input terminal and said control electrodes, a, connection between said positive electrode voltage source terminal and the positive electrode of the said initiating discharge device, a connection between the cathode of the initiating discharge device and the anode of the extinguishing discharge device whereby the discharge devices'are connected in series, a pair of cathode impedances each connected between one of said cathodes and said ground terminal, and a relatively large condenser connected between the cathodes, whereby the positive electrode to cathode circuit of the initiating discharge device is energized from said positive electrode voltage source terminal and the extinguishing discharge device has voltage applied between the positive electrode and-cathode by the potential difference across the cathode im- A pedance of the initiating discharge. device, and successive electrical impulses applied to the input terminal first fire the initiating discharge de- 'vice and then the extinguishing discharge device with the ignition of the extinguishing discharge device simultaneously raising the cathode potential of the initiating discharge device by the capacitive coupling between cathode to extinguish the discharge in both devices.

8. A circuit comprising a plurality of discharge devices including an initiating discharge device and an extinguishing discharge device, the extinguishing discharge device being of the vacuum type having an anode, an auxiliary positive electrode, a control electrode and a cathode, except for the extinguishing discharge device said discharge devices being of the gaseous discharge type each having a positive electrode, a control electrode and a cathode, an input terminal adapted to have electrical impulses to be counted applied thereto, a ground terminal, a positive electrode voltage source terminal, substantially non-conducting couplings between said input terminal and said control electrodes, means for holding the control electrode potentials sufiiciently low for normally preventing appreciable current conduction by the discharge devices, a plurality of current conducting cathode impedances each connected between one of said cathodes and said ground terminal, coupling elements for maintaining the potential diiference between the positive electrode and cathode of any discharge device substantially unchanged momentarily during ignition of the preceding discharge device, a connection between said positive electrode voltage source terminal and the positive electrode of the initiating discharge device, connecting means between the cathode of any discharge device and the positive electrode or the next for connecting the discharge devices in series with the initiating device first in the series and the extinguishing discharge device last, the

extinguishing discharge device being considered as a triode in said series circuit with the auxiliary positive electrode serving as the positive electrode of the triode, and means for momentarily fixing the potential difference between the cathodes of the first and last discharge devices, and a connection between the positive electrode voltage source terminal and the anode of the extinguishing discharge device, whereby the positive electrode to cathode circuit of the first discharge device is energized from the positive electrode voltage source terminaland any other discharge device except the extinguishing discharge device is energized by the voltage across the cathode impedance of the preceding discharge device in the series, the extinguishing discharge has ltsanode energized by said positive electrodevoltage source terminal and its auxiliary positiv electrode energized by the voltage across the cathode impedance of the preceding discharge device in the series, and each electrical impulse fires the first discharge device in the series which is not already conducting until the extinguishing discharge device is caused to become conducting and to raise the cathode potential of a first discharge for extinguishing all of the discharge devices.

' counted applied thereto, a ground terminal, an

the auxiliary positive electrode of the extinguish-- ing discharge device, and a condenser connected between the cathodes of the discharge devices, whereby the anode-cathode circuits of the discharge devices are supplied by said anode voltage source and the auxiliary positive electrode to cathode circuit of the extinguishing device is supplied by' the potential difierence in the oathode impedance of the initiating discharge device when the initiating discharge device is conducting, and whereby successive electrical impulses applied to said input terminal fire the initiating discharge device and then the extinguishing discharge device with the ignition of, the extinguishing discharge device simultaneously raising the cathode potential of the initiating discharge device by the capacitive coupling between the oathodes to extinguish the discharge in both devices.

PHILIP c. mom.