US2604263A

US2604263A - Variable frequency counter

Info

Publication number: US2604263A
Application number: US749849A
Authority: US
Inventors: Olin L Macsorley
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1947-05-22
Filing date: 1947-05-22
Publication date: 1952-07-22
Anticipated expiration: 1969-07-22

Description

July 22, 1952 o, acsoRLEY 2,604,263

VARIABLE FREQUENCY COUNTER Filed May 22, 1947 2 SHEETSSHEET l 3nveutor QwLMg/may g 082M Q avg; (Incl-neg Patented July 22, 1952 VARIABLE FREQUENCY COUNTER "01in MacSorley, Collingswood, N. .L, assignor to Radio Corporation of America, a corporation of Delaware Application May 22, 1947, Serial No. 749,849

10 Claims.

This invention relates to variable frequency counters such as are adapted (l) to provide a wide range of variation between the frequencies of their input and output pulses and (2) to automatically reset to their zero count or standby condition when the counting cycle to which they are adjusted is completed. Such devices include control means which are adjustable either to maintain a constant output frequency in response to a variable input frequency or to provide a variable output frequency in response to a constant input frequency. The present invention is illustrated as adapted to provide a constant output frequency in response to an input frequency which is adjusted in steps.

A variable frequency counter adapted to provide a variable output frequency in response to a constant input frequency is disclosed in a copending application'of W. H. Bliss, Serial No. 736,214, filed March 21, 1947, now Patent No. 2,521,774, issued Septemberl2, 1950. The counter of this copending application is disclosed as including four decades. Control of each of these decades to select any desired count is effected by means of a switch having three movable contacts which are mechanically fixed together, are connected to a common terminal, and engage separate rows of fixed switch contacts as they are moved from one position to another. These fixed contacts are connected to the anodes of the decade and are so arranged that counts of to 9 are selected as the movable contacts of the switch are moved from their firstto their tenth operating position. Each time the count of a decade corresponds to that for which the switch .is set, a more positive pulse is applied to the common terminal of the three contacts. When the overall count corresponds to the switch setting of all the decades, a control circuit is energized to deliver a pulse which is applied to an output terminal and is also utilized to automatically reset the counter to its zero count condition.

The variable frequency counter of the present invention is similar to that of the aforesaid application in that it includes a series of decades which are connected in tandem and each include a three-point switch for selecting any desired .count of the decade. It is distinguished from the invention of the aforesaid application in that improved means are provided for automatically re- .setting the counter to its zero count condition, provisions are made for accelerating the action of the high speed decade to which the input pulses are applied, and one of the decade selector switches is combined with that of a two stage counter to produce a desired result.

The principal object of the invention is to provide an improved variable frequency counter and method whereby a constant frequency output may be derived in response to a variable frequency input. Important objects of the invention are the provision of improved means for resetting a variable frequency counter; the provision of means for ensuring reliable operation of a counter at high operating frequencies; and the provision of means for combining the count selection switches of the low speed or high order end of the counter. a

The invention will be better understood from the following description considered in connection with the accompanying drawings and its scope is indicated by the appended claims.

Referring to the drawings:

Fig. 1 is a wiring diagram of a variable frequency counter connected in accordance with the invention;

Figs. 2 to 5 are explanatory curves relating to the operation of the counter of Fig. 1; and

Fig. 6 is a wiring diagram of a modified trigger circuit which may be used in the high speed decade of the variable frequency counter of Fig. 1.

The counter of Fig. 1 includes a high speed decade comprising the duotriodes 20 to 23, an intermediate speed decade comprising the duotriodes 24 to 21, a low speed decade comprising the duotriodes 28 to 3| and two additional duotriodes 32 and 33. Input pulses 295 of negative polarity are applied from a lead 34 through the crystal diodes 35 and 36 to the grids of the duotriode 20. Output pulses are applied from an output lead 31 through a capacitor 38 to a reset circuit which includes a duotriode 39 and a tetrode 4D. The number of input pulses required to produce one output pulse is determined by the setting of the selector switches of the different decades. If the output frequency is to be maintained constant, it is necessary that the setting of the selector switches be changed at each change in input frequency.

These selector switches 81, 94, and 96, which are shown immediately below the decades which they control, have their movable contacts connected through gates of the duotriode type to the output terminal 31. Thus the three movable contacts 4|, 42 and 43 of the selector switch of the decade 20-23 are connected through the duotriodes 44, 4'5 and 46 and the leads 4! and 48 to the output lead 3'! so that the lead 3'! is made more positive when the count of the decade 2ll-23 corresponds to the setting of the movable contacts 4I--42-43 of the selector switch of this decade. Likewise the three movable contacts 49,

50 and 5| are connected through a duotriode 52 and a lead 53 to the output lead 3'! so that this lead is made more positive when the count of the decade 24-21 corresponds to the setting of the contacts 49, 50 and 5|. Similarly, the three movable contacts 54, 55 and 56 of the selector switch of the decade 28-3l and the single movable contact 5'! of the selector switch of the counter units 32 and 33 are connected through a duotriode 58, a lead 59 and the lead 48 to the output lead 31 so that this lead is made more positive when the count corresponds to the setting of the contacts 54 to 51. I

During the counting operation, the more positive potentials mentioned above must be simultaneously applied to the output lead 3'! in order to activate the reset circuit. Thus a more positive potential is established at the lead 59 when the count of decade 28-3l and stages 32 and 33 corresponds to the setting of the contacts 54 to 52', at the lead 53 each time the count of decade 24-21 corresponds to the setting of contacts ii), 50 and 53, and at the lead 41 each time the count of the decade -23 corresponds to the setting of the contacts 41,42 and 43. When these three potentials are -all at their most positive value, the reset tube 39 is biased on and one output pulse is produced at a lead '69 which is connected to a counter reset lead 61 and the output lead 62.

The character of the pulses produced at the leads 3'! and 60 are to be discussed hereinafter in considerable detail for the reason that they relate to important features of the invention. As already indicated, these pulses are dependent on the potentials produced at the fixed terminals of the various selector switches by the trigger circuits of which the counter is constructed. It "is therefore necessary to consider the circuit connections of the trigger circuits, their interconnections with one another, their connections to the fixed contacts of the'selector switches, and the arrangement of these fixed contacts with respect to one another. v

All the trigger circuits of the counter are of a type wherein two triodes each has its anode crossresistor shunted by a capacitor so that current conduction is in either one or the other of the triodes. s 7 s Thus the first trigger circuit of the decade 28-23 has its anode 6'5 cross-connected to its grid 68 and its anode 66 cross-connected to its grid 61.

The cathode of this trigger circuit is grounded through resistors 63 and 64 and operating potential is applied to the anodes 65 and 66 from a +3 lead 69 through a resistor Hi which functions to maintain all the anodes of the decade at the potential level required for proper operation of the counter. With these connections, the application of a negative pulse from the lead 34 through the diode crystals and 36 to the grids 61 and 68 functions in a well known manner to transfer current conduction from the conducting to the non-conducting triode of the trigger circuit.

The other three trigger circuits of the decade 20-23 are similar to the first. All of them are connected in tandem through the coupling capacitors l3, l4 and 15. An important feature of the decade 20-23 is the connection of the anode 16 of the last stage through a crystal diode 11 to the right-hand grid 18 of the third stage and through a diode crystal 19 to the right-hand grid 80 of the second stage. With these connections, the operation of the decade 20-23 is as indicated by the following tabulation wherein the number connected to the grid of the other through a of pulses applied to the input lead 34 are shown in the first column and the current conductin condition of the various stages are indicated by R (righthand triode) and L (left-hand triode).

Tabulation No. 1

Trigger Circuit Number Pulse No.

R R R R L R R R R L R R L L R R R R L R L R L R R L L R L L L R R R R L L L L L L L L R R R R It is apparent from the above tabulation that a negative pulse is produced at the anode '15 of the last stage in 'responseto eight input pulses and at the anode 81 of this stage in response to ten input pulses.

Such negative pulse at the anode '16 functions to transfer current conduction from the righthand triodes to the left-hand triodes of the-second and third stages so that the operating cycle of the decade 29-23 is completed in response to ten input pulses. This type of feedback is disclosed in a copending application of I.'E.'Grosdofi, Ser. No. 580,446, filed March -1, 1945, now Patent No. 2,521,788, issued September 12, 1950.

Output pulses of negative polarity are fed to the input terminal 82 of the decade 24-21 through a capacitor 83 from oneor the other of the anodes i8 and 8| depending on the setting of themOvable contact 83 which cooperates with fixed contacts 0, I, 2 and 3 (connected to the anode 16) and fixed contacts 4 to 9 (connected to the anode 8|). This switch as a whole is indicated by the reference numeral 84. Its purpose is hereinafter explained in connection with the form'of pulse which is effective to operate the reset circuit previously mentioned. I

Associated with the decade 20-23 is a switch which includes a moVablecontact-BB and fixed contacts 0 to 5. The function ofthis switch-is to connect the right-hand grid 68 of the first stage to the reset lead 61 only when this stage is not in its zero count condition. The purpose of this is to avoid interference between the'inp'u't pulses which may be applied continuously and the reset pulse which might "otherwise operate the stage to produce inaccuracy of the count.

The three point switch which controls the application of the anode potentials of the decade 20-23 to the gates 44, 45 and 46 *is indicated by a general reference numeral '8'! for convenience of reference. it includes the'mova'bl'e contacts 4|, 42 and 43 and'th'ree corresponding groups of fixed contacts. Each group of fixed contacts is numbered 0 to 9 like the fixed contacts of the switches 84 and 85. As indicated by'b'r'oke'n lines, the movable contacts of the's'witches 84, 85 and 81 may be all'gangecl "togethe'rso that each" movable contact engages the "same "numbered fixed contact in all the switch positions.

By' assuming any desired position or the movable contacts 4|, 42 and 4-3 of the switch fljl are all least positive only when the'numbe'r 'of input pulses corresponds to thepa'rticula'r switch setting. Thusif the switch 81 is set at the number 5 contacts which are connected respectively to the left anode of the first stage, the right anode of the second stage and the left anode of the third stage, it is evident from the tabulation that the movable contacts 4|, 42 and 43 are all at their more negative potentials only when five input pulses have been applied to the lead 34. The same is true for all the other settings of the switch 81.

As hereinafter explained in greater detail, these more negative pulses of the movable contacts 4|, 42 and 43 are combined and reversed by the triodes 44 and 45, then passed through the gate 46 to give a single reversed pulse which is again reversed and amplified by the second half of the duotriode 46 so that a more positive pulse is applied to the lead 41.

The remaining stages of the counter differ from the stages of the decade 20-23 in that (l) anode potential is applied from the lead 69 through a common resistor 83 to the individual anode resistors, (2) input pulses are applied between the different stages through capacitors 89 to a terminal at the junction of the common and individual resistors, (3) feedback connections of the decades 24-21 and 28-3l are made through capacitors 90 to 93 instead of crystal diodes, and (4) the feedback in each decade is from the last to the third and from the third to the second instead of from the last to the second and third stages.

The use of crystal diodes in the grid circuits of the first decade 20 to 23 has the advantage that it facilitates more rapid operation of this stage. The second and third decades operate at speeds which permit the use of capacitors throughout the circuit. It is, of course, apparent that the decade 24-21 counts tens, the decade 23-3! counts hundreds, and the stages 32 and 33 count thousands. The operation of the decade 24-21 is apparent from the following tabulation wherein the input pulses are each indicated as a group of 10.

Tabulation No. 2

The operation of the decade 28-3! is similar to that of the decade 24-21 with the exception that each impulse applied to it represents 100 pulses applied to the lead 34. Similarly, each input pulse to the stages 32 and 33 represents 1000 input pulses applied to the lead 34.

Three oint switches 94 and 95 similar to the three point switch 81 are provided for applying the anode potentials of the decade 24-2! and the decade 28-3l respectively to the gate 52 and the gate 58. Ganged with the switch 95, as indicated by a broken line, is a switch 96 by which the counts of the stages 32 and 33 are combined with the counts of the decade 28-3] to produce a result to be explained in greater detail.

Assuming the switch 94 to be set fora count of 70, as indicated by the numeral '7 adjacent its corresponding fixed contact, it is seen that the movable contact 49 is connected to the righthand anode of the stage 24, the movable contact 50 is connected to the left-hand anode of the stage 25, and the movable contact 5| is connected to the right-hand anode of the stage 21. Referring to Tabulation No. 2, it is seen that all the anodes to which these movable contacts are connected are not conducting current in response to the 70th input pulse and are therefore at their more positive potentials. These more positive potentials are combined and amplified in the gate 52 and function to produce a more positive pulse at the lead 53. In the same manner, each setting of the switch results in a more positive potential at the lead 53 when the number of input pulses correspond to the selected setting of the switch 94.

While the decade 28-3] is similar to the decade 24-21, its three point switch has a somewhat different arrangement .of its fixed contacts as indicated by the reference numerals which are adjacent the fixed contacts and have the same significance'as in the cases of the switches 81 and 94.

Assuming the switches 95 and 96 to be set in their illustrated positions, it will be noted that the contact 54 is connected to the left-hand anode of the stage 28, the contact 55 is connected to the right-hand anode of the stage 30, and the contact 51 is connected to the left-hand anode of the stage 3|. Since all these anodes are not conducting current at a count of four hundred input pulses and are therefore at their more positive potentials, a more positive potential tends to be applied to the gate 58. This potential is not sufficient to openthe gate because of the negative potential applied to it from the righthand anode of the stage 32. When the number of input pulses reaches 1400, however, the gate 58 is opened and the lead 59 is made more positive.

As the movable contacts 54, 55, 56 and 51 are moved to the right, the gate 58 is opened successively in response to input pulses numbering 1500, 1600, 1700, 1800, 1900, 2000, 2100,2200 and 2300. This particular-arrangement is provided to facilitate the maintenance of a constant frequency of 31.25 cycles at the output terminal 62 while the input frequency at the lead 34 is changed by equal steps from 43,750 to 74,6875 cycles.

- With the switch settings previously assumed, one output pulse is produced in response to 1475 input pulses. Such a single output pulse may be produced by input pulses numbered from 1400 to 2399 with the switches 95 and 96 ganged together as illustrated. 'Thus if the input frequency is 43,750 cycles and the output frequency is to be kept at 31.25 cycles, the selector switches are set at 1400. Similarly the selector switches are set at 1410 for an input frequency of cycles at 1430 for an input frequency of 16 cycles at 1440 for an input frequency oi.

cycles cycles, etc.

As indicated above but'not explained in detail, the anode voltages of the various stages of the counter are applied through the three point selector switches 81, 94 and 95 and the one point switch 96 to the isolating-tubes 44 and 45 and to. the gate tubes 40, 52 and-58 for producing a reset or output pulse in response to a number of input pulses corresponding to the setting of the selector switches.

These tubes are illustrated as of the duotriode type, only one of the triodes being utilized in the case of 44. The more negative potentials of the switch 81 are applied respectively to the grid of the tube 44 and to the grids of the tube 45. As a result, the tubes 44 and 45 draw less current through their anoderesistors and a more positive potential is applied to the left-hand grid of the gate 46. When all three of the triodes of '44 and 45 are non-conducting, sufficient voltage is applied to the grid to override the (bias and cause 46 to conduct, thus increasing the current of its left-hand triode and applying a more negative potential to its right-hand grid so that the current of its right-hand triode is reduced and a more positive potential is applied to the lead 41.

In previously known means of combining the anode voltages of a decade counter, it has been customary to insert large isolating resistors in the fixed contact leads of the selector switch and to connect the selected ones of these resistors through the movable switch contacts to a common terminal which is connected to the grid of the gate tube. The disadvantage of such a combining system is that the large isolating resistors in series with the input capacity of the gate tube produces a slope on the leading edge of the pulse applied to the grid of the gate tube so that the gate tube is operated a fraction of a cycle late.

By using the threeisolating triodes 44 and 45, as explained above, the gate tube control voltage wave is made to have about the same steepness as those ofthe anode voltage waves. At the same time there is maintained such complete isolation between the anodes of the decade as is required to prevent interference with the operation of the decade by variation in the selector switch settings.

It should 'be noted that the cathodes of the isolating tubes 44 and 45 are all connected together and are so biased as to conduct only when a more positive voltage is applied from the selected anodes of the decade.

The operation of the gate tubes 52 and '58 is readily understood without detailed explanation. When a more positive pulse is applied from the selected anodes to their left-hand grids, more current is drawn by their left-hand triodes, the potentials of their right-hand grids is made more negative, the current of their right-hand triodes is reduced and more positive potentials are applied to the leads 53 and 59.

The more positive potential which is applied to the lead 31 in response to the selected number of pulses applied to the input lead 34 is now to be considered in connection with Figs. 2 to 5. Fig. 2 is a diagrammatic indication of the composition of the potential applied to the lead 31. The potentials applied through gate 48 are indicated by straight lines, the potentials applied through the gate 52 are represented by square waves of short width, and the potentials applied through the gate 58 are indicated as square waves of larger width.

It will be noted that these gated potentials are superimposed on one another, as indicated by the reference numeral 91, when the number of pulses applied to the input lead 34 corresponds to the setting of the selector switches 81, 94, and 95. This pulse 91 makes the right-hand grid of the peak detector 39 more positive, more current is drawn through the right-hand anode resistor, the potential of the left-hand grid is made more negative, less current is drawn through the lefthand anode resistor and a positive pulse potential is applied to the grid of the tube 40. As a result, the tube Mitriggers, drawing a large pulse of current through its cathode resistor and a positive pulse potential is applied to the lead 60. This potential is applied (1) to the output lead '62 and (2) to the reset lead 6| which is connected to the right-hand grids of the various stages of the counter. When this more positive potential is so applied to these right-hand grids, all the stages of the counter are reset to their zero count or standby condition with current in their right-hand anodes. The effect of this on the potentials at 3! is shown in Fig. 2.

In connection with Fig. 2, it has been assumed that all the voltages change instantaneously. Actually, the step fromthe potential of the second gate to that of the first gate may have a curvature on its front edge as indicated at 98 in Figs. 4 and 5 wherein the anode potentials of the first and second decade are shown much wider than in Fig. 1. Assuming the pulses of the first gate to have straight sides, this curvature results in a control and reset pulse occurring a fraction of a second later than it should.

Such inaccuracy is minimized or obviated by the provision of the switch 84 connected between the first and second decade. This switch functions to advance the time (but not the rate) at which pulses are fed to the second decade when its movable contact 83 is in engagement with the fixed contacts 0 to 3. The resulting effect, as indicatedby Fig. 5, is to advance the beginning of the Second Gate potential so that the First. Gate potential is not superimposed on the curved portion 98 of the Second Gate potential. In this manner, correct timing of the reset and output pulses is assured. This feature is, of course, useful in many other cases where superimposed voltages are derived through a plurality of gates from sources of potential which are of a wave form subject to curvature.

In resetting a variable frequency counter, such as that of the present invention, the most critical point is the first stage of the high frequency decade. The first stage must trigger rapidly and be ready to accept the next input pulse with a minimum of delay- Before the counter can begin anew count it obviously must be reset to' its initial condition. If the first stage of the counter has been left by the previous count in its zero count condition, with current in its right hand anode, a condition which occurs for even counts, the first stage need not be reset. It is advisable not to apply a reset pulse to the stage-when in its zero count condition, since this may cause holdover, and the next applied pulse to be counted may be missed. If, as the result of an odd-numbered count, the first stage is left in a condition with current in its left hand anode, it must be reset to its zero count condition in order to function properly for the new count. For all odd numbered settings of the selector switch which derive a voltage from the left anode, this first stage must be reset and ready to operate in less than one cycle so that no counts are missed. For all even numbered settings of the selector switch which derive a voltage from the right anode, the first stage must not be reset and must not hold over for an extra cycle. These conflicting requirements are met by applying the reset potential to the right-hand grid of the first stage of the high frequency decade only on the odd counts. This is accomplished by the switch 85 which has its odd numbered fixed contacts connected to the reset lead GI and has its movable contact 86 connected through a relatively high resistance to the right hand grid of the first stage so that the reset pulse applied to this grid is of an amplitude reduced to the optimum value for the condition under which this stage is operated. The first stage is thus reset at a maximum speed.

The feed-back connections of the decades 20-23, 24-21 and 28-3! may be modified as indicated by Fig. 6. This modification consists in feeding back from the left-hand anodes of the stages 21 and 26 to right hand grid of the stage 25. The operation of the decade with this type of feedback is shown by the following tabulation which has the same significance as the previous tabulations.

Tabulation No. 3

Trigger Circuit Number Input Pulse No.

R R R R R R L R R L R R R L R L .r L L R R R L L L R L R L L L L L L R R R With this type of feedback, it is essential that the feedback coupling units 99 and be unilateral conductors so that the feedback pulses are of only one polarity; otherwise the feedback pulse from stage 21 would be cancelled by one of opposite polarity from stage 26. The advantage of this type of feedback connection is that it produces in the various stages wave forms more suitable for use for some applications than those produced by the feedback connections shown by Fig. 1. How the fixed contacts of the selector switch are to be connected to the anodes of this decade is apparent from the above Tabulation No. 3.

What the invention provides is (1) an improved counter which is operable to produce a constant frequency in response to a variable frequency or vice versa, (2) an improved circuit connection for resetting the first stage of the high speed decade of the counter, (3) an improved system of combining the potentials selected from different groups of counter stages to produce an output-pulse which is accurately shaped, (4) an improved means of channeling the selected'anflde potentials of a decade to the gate through which they are passed for combination with similar potentials from other decades or groups of stages, (5) means for inter connecting a higher speed decade or group of stages with a lower speed group of stages so that one selected count of the lower speed group is combined with one selected part of the counts of the high speed group and another selected count of the low speed group is combined with another selected part of the counts of the high speed group, and (6) a decade counter with an improved system of feed-back connections whereby voltage disturbances in the various stages of the decade are minimized.

I claim as my invention:

1. The combination of a counter having a plurality of tandem-connected stages each including a pair of electron discharge elements which have operating potential applied to their anodes through separate impedance elements and have their grids each connected to the anode of the other sothat current conduction is stable either in one or the other of said elements, means for applying a reset potential to a corresponding grid of all but the first of said stages, and'means for applying to the corresponding grid of said first stage a reset potential of a value, different from that applied to the corresponding grids of the other of said stages.

2. The combination of acounter having a plurality of tandem-connected stages each including a pair of triode elements which, have operating potential applied totheir anodesthrough separate impedance elements and have their grids each connected to the anode of the other so that current conduction is stable either in one or the other of said elements, a source of reset potential, a plurality of resistance elements having substantially the same value each connected between said source ,of reset potential and a corresponding grid of all but the first of said stages, and meansfor connecting a resistance element having a value which is high relative to the value of one of said plurality of resistance elements be tween said source and the corresponding grid of the first of said stages.

3. The combination of acounter having a plurality of tandem-connected stages each including a pair of electron discharge elements which. have operating potential applied to their anodes through separate impedance elements and have their grids each connected to the anode of the other so that-current conduction is stable either in oneor the other of said elements, a source of reset potential, a plurality of resistance elements each connected between said source of reset potential and a corresponding grid of all but the first Of said stages,,and means for connecting a resistance element having avalue which is high relative to the value of one ofsaid plurality of resistance elements and a capacitor between said source and the corresponding grid of the first of said stages.

4. The combination of a counter having a plurality of tandem-connected stages each including a pair of triode elements which have operating potential applied to their anodes through separate impedance elements and have their grids each connected to the anode of the other so that current conduction is stable either in one or the other of said elements, means for applying a reset potential to a corresponding grid of all but the first'of said stages, and means for applying a reset potential to the corresponding grid of said first stage only when said first stage is not in its zero count condition. I

5. The combination of a counter having a plurality of tandem-connected stages each including a pair of electron discharge elements which have operating potential applied to their anodes through separate impedance elements and have their grids each connected to the anode of the other so that current conduction is stable either in one or the other of said elements, means for applying a reset potential to a grid of all but the first of said stages, means for applying a reset potential to a grid of said first stage only when said first stage is not in its zero count position, means connected to said anodes for selecting groups of potentials which are made of one polarity simultaneously in response to the application of successive pulses to the first of said stages, means including a plurality of triode elements having their grids connected to said se lecting means for producing a single potential responsive to said selected potentials, and means including a pair of triode elements responsive to said single potential for producing a potential which is representative of the selected count of said counter.

6. The combination of a counter having four stages each including a pair of triode elements which have operating potential applied to their anodes through separate impedance means and have their grids each connected to the anode of the other so that current conduction is stable either in one or the other of said elements, means for interconnecting said stages so that the operating cycle of said counter is completed in response to the application of ten pulses to the first of said stages, means for applying a reset otential to a grid of all but the first of said stages, means for applying to the corresponding grid of said first stage a reset potential only when said first stage is not in its zero count position, means to attenuate said reset potential applied to said first stage to have its optimum reset value, means connected to said anodes for selecting groups of three potentials which are made of one polarity in response to the application of successive pulses to the first of said stages, and means connected to said potential groups selecting means to produce a single potential in response to said selected potentials.

7. The combination of a counter having different groups of stages each of which stages includes a pair of electron discharge elements having operating potential applied to their anodes through separate impedance means and having their grids each connected to the anode of the other so that current conduction is stable either in one or the other of said elements, means interconnecting the stages of each group so that its operating cycle is completed in response to the application of a predetermined number of input pulses, said different groups being connected in tandem, switch means to connect a first of said groups to a second of said groups to advance the time of application of driving pulses from said first group to said second group for low orders of counts in said second group, separate means connected to the anodes of each group for selecting potentials which are made of the same polarity in response to successive ones of its input pulses, and means for combining all of said selected potentials to produce a single potential representative of said selected potentials.

8. The combination of a counter having different groups of stages each of which stages includes a pair of triode elements having operating potential applied to their anodes through separate im- 12 pedance means and having their grids each connected to the anode of the other so that current conduction is stable either in one or the other of said elements, means interconnecting the stages of each group so that its operating cycle is com pleted in response to the application of a predetermined number of input pulses, said difierent groups being connected in tandem, switch means to connect the last stage of a first of said groups to the first stage f a second of said groups to advance the time of application of driving pulses from said last stage to said first stage for low orders of counts in said second group, separate means connected to the anodes of each group for selecting potentials which are made of the'same polarity in response to successive ones of its input pulses, and means for combining all of said selected potentials to produce a single potential representative of said selected potentials and means responsive to the peak of said single potential for producing an output pulse.

9. The combination of a counter having dinerent groups of stages each of which stages includes a pair of electron discharge elements having operating potential applied to their anodes through separate impedance means and having their grids each connected to the anode of the other so that current conduction is stable either in one or the other of said elements, means interconnecting the stages of each group so that its operating cycle is completed in response to the application of a predetermined number of input pulses, said groups being connected in tandem, a selector switch connecting one of the anodes of the last stage of a first of said groups to the first stage of a secondof said groups to advance the time of application of driving pulses from said last stage to said first stage for low orders'of counts in said second group and connecting the other of the anodes of said last stage to said first stage for high orders of counts in said second group, separate means connected to the anodes of each group for selecting potentials which are made of the same polarity in response to successive ones of its input pulses, and means for combining all of said selected potentials to produce a single potential representative of said selected potentials and means responsive to the peak of said single potential for resetting said counter to its zero count condition.

10. The combination of a counter having difierent groups of stages each of which stages includes a pair of triode elements having operating potential applied to their anodes through separate impedance means and having their grids each connected to the anode of the other so that current conduction is stable either in one or the other of said elements, means interconnecting the stages of each group so that its operating cycle is completed in response to the application of a predetermined number of input pulses, said groups being connected in tandem, a selector switch con necting one of the anodes oi. the last stage of a first of said groups to the first stage of a second of said groups to advance the time of application of driving pulses from said last stage to said first stage for low orders of counts in said second group and connecting the other of the anodes of said last stage to said first stage for high orders of counts in said second group, separate means connected to the anodes of each group for selecting potentials which are made of the same polarity in response to successive ones of its input pulses, said switch means being connected to said first group selecting means to be adjustable therewith, means for combining all of said selected po- 13 s 14 tentials to produce a single potential representa- Number Name Date tive of said selected potentials, means including a 2,407,320 Miller Sept. 10, 1946 triode element so biased as to conduct current 2,411,714 De Rosa Nov. 26, 1946 only in response to the peak of said combined 2,416,095 Gulden Feb. 18, 1947 single potential, and means responsive to said 5 2,422,698 Miller June 24, 1947 peak-produced current for producing an output FOREIGN PATENTS pulse.

N L, L Y, Number Country Date 355,705 Great Britain Aug. 24, 1931 The following references are of record in the vacuum Tube scaling Circuits of Arbi me of this patent: trary Integral or Fractional Scaling Ratio; Lif- UNITED STATES PATENTS schultz Phys. Review, volume 57; p. 243, 1940.

Number Name Date 15 2,381,920 Miller Aug. 14, 1945