US2503662A - Electronic valve apparatus suitable for use in counting electrical impulses - Google Patents

Description

frwenr 730772019 f77/@wam JAA 'r.-H. FLOWERS ELECTRONIC vALvE APPARATUS SUITABLE FOR usE Filedv Nov. 2o. 1945 IN COUNTING ELECTRICAL IMPULSES April 11, 195o Patented Apr. l1, 1950 ELECTRONIC VALVE APPARATUS SUITABLE FOR USE IN COUNTING ELECTRICAL IM- PULSES Thomas Harold Flowers, London, EnglandA Application November 20, 1945, Serial No. 629,856 In Greatv Britain November 17, 1944/ Section 1, Public Law 690, August 8, 1946A Patent expires November 17, 1964y (Cl. Z50-27) 4 Claims. l

This invention relates to electronic valve apparatus which is suitable for use in counting electrical impulses.

In known apparatus for counting electrical impulses a number of electronic valves have been arranged in ring formation, being interconnected in such manner that each valve in turn becomes non-conducting while the remainder of the valves in the ring formation are conducting. This condition of conducting and non-conducting valves is a stable condition that is, the electron flow in each valve is unchanged until an electrical impulse is impressed on the input of the apparatus whereupon the non-conducting yvalve becomes conducting, and one of the other valves in the formation becomes non-conducting. The term stable condition of electron flow in this usage includes the case when a Valve is non-conducting.

In the known apparatus the attainment of the stable conditions, in number equal to the number of valves in the ring formation, has been mainly accomplished by applying to the grid yof each valve, direct current voltages derived from an electrode, usually the anode, of the othervalves of the formation,l each grid being connected to all the other valves through suitable resistances. The selection of a different' valve to be non-conducting and the production of a diii'erent stable condition was effected by applying a transient Voltage or voltage impulse to the same grid of the next valve to be made non-conducting as the grid to which the direct current voltages are applied, this voltage impulse being obtained by feeding back through a condenser a portion of the voltage change of one electrode, usually the anode, of each valve in the ring formation to the said grid of the said next valve. f

In the known apparatus the changing from one stable condition to another, i. e. the selection of a different valve to be non-conducting, has been uncertain and the operation of the appara'- tus consequently impaired.' It is an object of this invention to provide apparatus of the kind referred toin which the change from one stable condition to another is made more certain when an electrical impulse is applied to the input. It is a further object of the invention to provide electrical impulse counting apparatus which is more reliable and accurate than has been hitherto possible.

The invention, accordingly, provides' electronic valve apparatus adapted in response to electrical impulses received at its input, to produce at its output electrical impulses which are lower in number than and are in pre-determined numerical relation with the number of received impulses and having a number of valves interconnected in a ring formation such that each Valve in turn is caused to attain a stable condition of electron flow which is different from that of the other valves in the formation wherein the valves are of the multi-grid type and the attainment of the stable conditions of electron flow in the various Valves is determined by means arranged to apply to a grid of each valve direct current voltages derived from the circuits of the other valves of the ring formation and wherein the selection of each valve in turn to attain said different condition of electron flow is eiected by means arranged to apply a transient voltage or voltage impulse to a grid of the valve required to be selected other than the grid to which the said direct current voltages are applied.

The invention will be described, by way of example, with reference to the accompanying drawing Whichshows a diagrammatic arrangef ment of apparatus arranged as a scale-of-three counting device.

For convenience, the application of the steady f direct current voltages in the manner` referred to is termed D. C. feed-back and the application of a transient voltage or a voltage impulse is termed A. C. feed-back.

Referring to the accompanying drawing, valves I, 2 and 3 are multi-grid valves of the pentode type arranged to form a ring of three elements.

The kcathocles of these valves are connected to earth and their anodes are connected via resistors Il, 2|, 3| respectively to the positive terminal of a battery VI, the negative terminal of the battery being connected to earth. The D. C. feed-back to valve I is provided via resistor I2 which connects the anode of valve 2 and resistor I3 which connects the anode of valve 3 to the control grid of valve I via the grid resistor I4. Similarly the'resistors 22 and 23 connect the anodes of Valves 3 and I respectively to the control grid of Valve 2 via grid resistor 24, and re-l sistors 32 and 33 connect the anodes of valves land 2 respectively to the control grid of valve 3 Via grid resistor 34. The voltage changes due to the D. C. feed-backs are brought to suitable points on the grid-Voltage anodes-current characteristics of valves I, 2 and 3 by the negative voltagel from battery V2 connected via resistors I5, 25, 35 respectively to the common connections of the D. C. feed-back resistors I2, I3 for valve L22, 23 for valve 2, and 32, 33 for valve 3. The A. C. feed-back to valve I is applied by connecting the anode of valve 3 viacondenser I6 in series with resistor I1 to the suppressor grid of valve I which is further connected via resistor I8 to earth. Only a portion of the anode voltage change or voltage impulse of valve 3 is thus fed back to the suppressor grid of valve I. If the whole or too great a portion is .fed back the circuit tends to oscillate continuously, The A. C. feedback to valves 2 and 3 can be similarly traced via condenser 26 and resistors 21, 28 for valve 2 and condenserv 36 and resistors 3'! and 35i for valve 3. The screen grid of valve I is joined to the positive of battery VI via resistor IS. The screen grids of valves 2 and 3 are similarly joined via resistors 29 and 33 respectively.

Impulses to drive the apparatus are applied to the input of the apparatus via lead LI. is arranged with its cathode joined via resistor 4i to earth, its anode connected to the positive of battery VI and its grid biased negatively by resistors 42 and 43, and with condensei` 44 interposed between the grid and the applied impulses in a known manner for ensuring that only positive impulses are allowed to pass to the ring valves I, 2 and 3. Positive impulses at Li produce positive impulses at the cathode of valve Ll, which is connected via condensers lil, 20, 3@ to the grids of valves I, 2 and 3, respectively, via their grid resistors I4, 24, and 34 respectively.

Valve 5 with its cathode resistor 5I, grid resistors 52 and 53 to produce negative bias and condenser 54 connecting its grid to the anode of valve I, serves in the manner of valve 4 to pass positive impulses to the output lead L2 and along this lead to drive the next scale of the counter or to operate indicating or integrating devices of known character, not shown.

The usual means of heating the valve cathodes is employed but is not shown.

By suitably choosing the resistance, condenser and battery voltage values, valves I, E and 3 are arranged to have three stable conditions corresponding to the three combinations in which one of the valves has its anode current cut on and the remaining two are fully conducting, that is, their control grids are passing grid current. Each impulse impressed on lead LI, provided that there is a certain minimum interval between the impulses, causes the cut-ofi condition to be transferred to the next valve in the given sequence, which in the present case is I, 2, 3, I, 2, 3, etc.

The cut-01T condition of valve l corresponds to zero on the counter scale. The scale may be set to zero vbefore a count by connecting the screen grid of valve I to a potential negative to earth by means not shown or may be so set by other known means. Each time the anode current of valve I is cut-01T during a count, an impulse is passed by way of valve 5 to the neXt counter scale via lead L2.

To trace the transition from one to another stable condition assume that valve I is non-conducting and valves 2 and 3 are both conducting before an impulse is received on lead LI and that sufcient time has elapsed since the last impulse for substantially steady state conditions to have been reached by voltages on the sundry condensers. A positive impulse of suiiicient magnitude applied to le-ad LI will cause the cathode of valve 4 toapply a positive pulse to each of the condensers III, 2li, 3B. This pulse will be communicated to the control grid circuit of each valve I., 2, 3. It will produce no eiect on valves 2 and 3 because these valves are already passing grid current but valve I will become conducting and will be maintained conducting by the D. C. feed- Valve ai 4 back from valve 2, the anode of which is rendered non-conducting as next described. The potential of the anode of valve I becoming less positive acts via condenser 26 and resistors 2l, 28 to impress a negative voltage impulse on the suppressor grid of valve 2 and thus render the anode of valve 2 non-conducting by diverting the cathode emission from the anode to the screen grid. The resistors I9, 29, 3S, in series with the screen grids of valves I, 2, 3 are desirable to protect the screen grids from excessive currents under this condition. The anode of valve 2 remains non-conducting provided that during the attainment of steady state conditions by the condensers the negative suppressor grid voltage remains eiective until the reduced D. C. feed-back to valve 2 lowers the voltage of the grid to a value such as would normally reduce the anode current to zero. This condition is easily satisfied by suitable choice of condenser sizes. The change of anode potential of valve 2 tends to make the suppressor grid of valve 3 positive with respect to its cathode but this has negligible eiect on the anode of valve 3. It is essential for reliable operation that the grid potential of a valve which has not changed its anode condition should remain substantially constant as otherwise undesirable variations in anode potential are produced. In the change of stable condition being described the condition of elec- 'ron iow in valve 3 does not have to change but the pulse applied to lead LI makes the plate of condenser 3l) nearer the grid of valve 3 first of all positive and then negative with respect to the steady state condition. The anode current of valve 3 is made to remain substantially constant under these conditions by arranging that the common connection of resistors 32, 33, 35 and condenser 30 is always during these conditions at a potential positive to that control grid potential of valve 3 at which grid current commences to now. The resistor 34 then allows the control grid potential to remain substantially constant. The volt.- ages at the common connection of the resistors I2, i 3 and I5 and condensers I0 and the common connection of the resistors 22, 23 and 25 and condenser 2i! are similarly determined at the appropriate times.

It will be appreciated that in any impulse counter of the type deiined the anodes of each valve in the counting ring will at the instant of application of an impulse be simultaneously under the influence of the impulse, the D. C. and the A. C. feed-backs to that valve. These influences may be contrary in their effects on the anode current of a particular valve and thus tend to render the desired change of anode condition` uncertain in its early stages. By applying the D. C. and A. C. `feed-backs according to the invention to diierent grids of a multi-grid valve uncertainty as to anode change of potential'is eliminated. In the example shown in the drawing and described in the foregoing the A. C. feed-back by applying negative voltage to the suppressor grid cuts the anode current 'off independently 'of 'the impulse and D. C. feed-baci: voltages, and thus produces a clean change over from the conducting to non-conducting condition. It will be appreciated that the invention can -be applied to a ring or scale of any number; In a particular application in which scale-oive units were required Vto count at a maximum rate of 2500 pulses per second, the following circuit elements were found towork'reliably, the component numbers being read in conjunction with the diagram.

Condenser 44, 54-0.001 microfarad. Resistor 42,52-100,000 ohms. Resistor 43, 53--e70,000 ohms. Resistor 4 I, 5 I-=i,700 ohms. Valve 4 and 5-L63. Anode resistors il, 2| etc-33,000 ohms. Screen grid resistors i9, 29 etc-10,000 ohms, D. C. feed-back resistors l2, i3 etc.1 megohm. Resistors I5,25 etc-1 megohm. Condensers l 0, 2li eter-0.00005 microfarad. Condensers i6, 26 etc- 0.0001 microfarad. Resistors I1, 21 etc-220,000 ohms. Resistors I8, 2S etc-220,000 ohms. Battery Vl-lOO volts. Battery V2--90 volts. Ring valves I, 2, 3, 4 and 5-EF 36.

I claim:

1. Electronic valve apparatus for counting elec trical impulses having input and output circuits, a plurality of electronic valves each having a plurality of electrodes including a plurality of grids and arranged in a ring formation with a load device in the output circuit of each valve, means responsive to successive electrical impulses at the input circuit for making each valve in turn non-conducting While the other valves are conducting, said means comprising a circuit arrangement connecting an electrode of each valve with one of the grids of each of -the other valves for applying a direct current voltage produced at the said electrode to each of said grids and a circuit arrangement connecting an electrode of each valve with a grid of the next succeeding valve in the ring formation other than the grid of said next succeeding valve to which the said direct current voltage is applied, said last mentioned arrangement being arranged to apply a transient voltage produced at said electrode to said other grid to make said next succeeding valve non-conducting.

2. Electronic valve apparatus for counting electrical impulses having input and output circuits, a plurality of electronic valves each having a plurality of electrodes including a plurality of grids and arranged in a ring formation with a load device in the output circuit of each valve, and means responsive to successive electrical impulses at the input circuit for making each valve in turn non-conducting While the other valves are conducting, said means including circuit connections for simultaneously applying electrical impulses at the input circuit to a grid of each valve whereby the non-conducting valve in the ring formation is caused to conduct, a circuit connecting means connecting an electrode of each valve with the same grid of each of the other valves for applying a direct current voltage to the respective grids, and a circuit arrangement connecting an electrode of each valve with a different grid of the next succeeding valve in ring formation for applying a transient voltage produced at the electrode to said different grid to make the adjacent valve nonconducting.

3. Electronic valve apparatus for counting electrical impulses having input and output circuits, a plurality of electronic valves each having a plurality of electrodes comprising a plurality of grids including a control grid and a suppressor grid and arranged in a ring formation with a load device in the output circuit of each valve, and means responsive to successive electrical impulses at the input circuit for making each valve in turn non-conducting while the other valves are conducting, said means comprising a circuit arrangement connecting an electrode of each valve with the control grid of each of the other valves for applying a direct current voltage produced at the electrode to each of said control grids, a circuit arrangement connecting the input circuit with each of said control grids for applying an impulse from said input circuit to each of said control grids, and a circuit arrangement connecting an electrode of each valve with the suppressor grid of the next succeeding valve in the ring formation for applyingatransientvoltage produced at said electrode to said suppressor grid to make said next succeeding valve non-conducting.

4. Electronic valve apparatus for counting electrical impulses having input and output circuits, a plurality of electronic valves arranged in a ring formation and each having an anode and a plurality of grids including a control grid and a suppressor grid, each said valve having a conducting and non-conducting-condition of stability and means responsive to successive electrical impulses at the input circuit for changing the condition of stability of each valve in turn, said means comprising a circuit arrangement connecting an anode of each valve with the control grid of each of the other valves in the ring formation for applying a direct current voltage produced at the said anode to each said control grid, a circuit arrangement connecting the input circuit With each of said control grids for applying an impulse from said input circuit to each of said control grids, and a circuit arrangement connecting an anode of each valve with the suppressor grid of the next succeeding valve in the ring formation for applying a transient voltage produced at said anode to said suppressor grid to make said next succeeding valve non-conducting.

THOMAS HAROLD FLOWERS.

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

UNITED STATES PATENTS Number Name Date 1,932,589 Holden Oct. 31, 1933 2,252,457 Cockrell Aug. 12, 1941 2,404,918 Overbeek July 30, 1946 OTHER REFERENCES Electrical Counting 1943, by Lewis, pages -92, The McMillan Company. Copy in Division 10.

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