US2349810A - Counter circuit - Google Patents

Description

May 30, 1944.

E. D. cooK 2,349,810

COUNTER CIRCUIT Filed Dec. l, 1941 I EN , 41; 45A @in i 4a gri I (DL) I am PRnmue colLs Figs. 1&1 Ll 1 l L Fg. /E4

Fg. fls n Figa. l/EG r- LA F12] l v Inventlor:

Ellsworth D. Cook His Attorney.

Patented May 30, 1944 COUNTER CIRCUIT Ellsworth D. Cook, Scotia, N. Y., signor to General Electric Company, acorporation of New York Application newsw- 1, 1941', sei-n1 No. 421,129

(ci. 25o-ss 3Cialma.

My invention relates to impulse counting and interval timing and concerns particularly circuits employing electric discharge devices.

It is an object of my invention to provide an arrangement for counting impulses accurately and with high precision of indication, which operates reliably in the case of high speed impulses.

It is also an object of my invention to provide a frequency divider.

Other and further objects will become apparent as the description proceeds.

Small time intervals may be measured by counting the number of lcycles of an accurately known frequency which occur between two input signals marking the beginning and the end of the required time interval. An example oi such an application is a velocity determining device in which a moving body passes in inductive relation to two current conducting coils in succession and thus creates two electrical signals which actuate auxiliary apparatus to* apply the accurateiy known frequency to the counter circuit during the time interval between the two signals. My" invention is not limited to time intervai measurement and relates generally to impulse or cycle counting. Nevertheless, shall explain my invention for use with time interval measurement.

carrying out my invention in its preferred form, l provide a vacuum tube circuit with an initial stage consisting of a pair ci tubes between which current shifts back arri forth with .successive heli cycles of the input signal, and I provide one or more frequency dividing stages. The initiai stage is arranged to convert input signals (which may be a sine wave or an oscillatory wave of some other form including a unidirectional pulsating Wave) into a square wave having positive loops only, of the same frequency as the input wave. Each divider stage includes a. pair of tubes for inverting alternate square wave impulses of the input to the divider stage and thus forming a peculiarly shaped half-frequency alternating-current wave with square components. These two tubes are provided with a half frequency alternating voltage bias control to produce their special action. The divider stage includes also a pair of tubes acting like the initial stage of the counting apparatus for converting the peculiarly shaped alternating wave into a square wave with positive loops only. The output of each divider stage is thus a square wave having half the frequency of the inputV thereto. Indicators are provided in each stage for showing whether an odd or an even number of 1mpulses has been supplied thereto. The total number of impulses counted can then be determined provided there are enough counter stages so that the input impulses terminate before the last divider stage is brought back to its initial condition.

A better understanding of the invention will be afforded by the following detailed description considered in connection with the accompanying drawing, and those features of the invention which are believed to be novel and patentable will be pointed out in the claims appended hereto.

In the drawing Fig. 1 is an electrical circuit diagram schematically representing an embodiment of my invention, and Figs. E to 7, inclusive, are graphs representing the .shape and character of voltage waves appearing at various portions of the circuits illustrated i. Fig. 2 represents the input voltage wave E: supplied tc the initial stage; Fig. 3 represents 'the square wave Es produced by the initial stage and supplied to the ilrst divider stage; Fig. i represents the bias voltage wave Es supplied to first two tubes of the first divider stage; Fig. 5 represents the voltage E5 produced by these two tubes; Fig. 6 represents the square wave Es produced by the first divider stage and which has half the frequency of the wave E3 supplied to this divider stage, and Fig. 7 represents a square wave corresponding to the wave Ea but having half the frequency thereof to represent the action of the second divider stage.

Fig. l. illustrates apparatus for counting .the impulses produced during a given time interval by a constant frequency generator I i, the frequency of which is known accurately. An arrangement ls provided for connecting the source II to the circuit during the required time in terval. Such a connecting arrangement is represented schematically by the switch I2. The counter circuit includes an initial stage I3 for squaring the input wave and cutting olf negative loops, a rst divider stage I4 consisting of the apparatus within the dotted rectangle I5, and the complete counter may includes one or more additional divider stages I6. The divider stage Il includesv a section I'I comprising a pair of electric discharge devices for inverting alternate impulses of the initial stage I3, a suitable generator I8 of half frequency impulses for supplying bias voltage to the section I'I, and a section I9 comprising a pair of electric discharge devices similar in action to the initial stage I3, for converting the output of the discharge devices I'I into a wave having only positive loops.

- pulses may be utilized as the generator I. Since my invention is particularly useful in the case of counting impulses which occur with high frequency, itis desirable to utilize a switching mechanism which may be controlled accurately under such conditions. For simplicity I have shown a switching arrangement in the form of a simple mechanical switch I2, as the switching arrangement is not claimed in the present application. For high frequency work an electronic switch or other suitable apparatus should be employed. For example, I may employ a control circuit of the type disclosed in my copending application, Serial No. 418,213, led November 7, 1941, Patent No. 2,332,300 granted Oct. 19, 1943, assigned to the same assignee asthe present application. If the source supplies an oscillatory vwave consisting of continuous-current impulses a condenser 8 may be interposed in the input lead to the stage I3. l

'Ihe initial stage I3 comprises a pair of electric discharge devices 2| and 22, together with va suitable source of energizing voltage and circuit connections. The devices 2| and 22 may take the form of high vacuum tubes, each having a, plurality of electrodes, including anodes 23 and 24l cathodes 25 and 26, and control electrodes or grids 21 and 28. For energizing the anode-cathode circuit, a voltage source 29 may be provided having positive and negative terminals represented by the terminals marked B+'and B-. The B+ terminal is connected to the anodes 23 and 24 through anode resistors 30 and 3|, respectively. The B- terminal and the cathodes 25 and 25 may be connected together and grounded but for reasons which will appear hereinafter I prefer to include a cathode resistor 32 in the cathode lead of the tube 2|. Cross-coupling resistors 9 and I9 are connected one between the control electrode 21 and the anode 24, the other between the control electrode 28 and the anode 23.

The output voltage E2 of the generator II is applied to the control electrodes 21 and 28 through connections arranged to supply voltages of opposite polarity to the two control electrodes. For example, the voltage Ez may be connected across a resistor 33 which has a center tap 34 and is connected at one end to the control electrode 21 and at the other end to the control electrode 28. In order to apply a negative bias to the control electrodes of the devices 2| and 22, -a sourceof biasing potential 35 may be connected between the mid terminal 34 of the resistor 33 and a ground connection for the cathodes 25 and 26. For carrying the output voltage En from the initial stage I3 to the next Cil aasaeio lplurality of electrodes including anodes, cathodes and control electrodes or grids. The anodes are connected to the B+ terminal of the source 29 through anode resistors 4I and 42 respectively. The control electrodes are connected to the output lead 36 from the initial stage I3 and the cathodes are connected to opposite ends of a rethe output leads 48 of the multi-vibrator I8 and the ends of the resistor 43 to insure proper wave stage a conductor 36 may be provided which is trodes or grids.

shape in this dynamic bias voltage. The` multivibrator I8 is constructed to operate at half the frequency of the generator I I and is synchronized with the generator II, e. g., by connecting input leads 43 of the multi-vibrator across the output terminals of the generator Il. The circuit of the multi-vibrator I 8 is not shown since it does not constitute a part of my present invention. A suitable form of multi-vibrator is shown at 38 in Fig. 3 of my copending application Serial No. 338,360, filed June 1, 1940, and assigned to the same assignee as the present application. In the vibrator shown in that application a tap 52 is provided for adjusting the circuit to operate at a predetermined natural frequency. The clipper circuit 41 may likewise take the form of circuits already known to those skilled in the art, such as illustrated at 39, for example, in my aforesaid copending application, Serial No. 338,360.

The nal section I9 of the frequency divider stage|4 may also take the form of vacuum tubes 49 and 50 each having a plurality of electrodes including anodes, cathodes and control elec- The tubes 49 and 50 are connected in a manner similar to the tubes 2| and 22. The anodes of each are connected through anode resistors to the B+ terminal of the source 29. The cathode of the tube 49 is connected to the ground lead through a cathode resistor 5|, tol the positive end of which the stage output lead 52 is connected. The control electrodes are connected across the ends of a resistor 53, the mid point of which is connected to the negative side of a voltage source 54 grounded on the positive side for negatively biasing the control electrodes of the tubes 49 and 50. The control electrodes of the tubes 49 and 50 are coupled to the anodes of the tubes 39- and 40, respectively, through coupling condensers 55 and 56. The tubes 49 and 50 are also resistance cross-coupled having a nected in responsive relation tothe anoderesistor 51, connected between vthe control electrode of the tube 49 and the anode of the tube 50 and a resistor 58 connected between the control electrode of the tube 59 and the anode of the tube 49.

If desired, one or more frequency divider stages represented by the rectangle I5 may beprovided each of which is similar to the apparatus shown within the dotted rectangle Il.- The hall' frequency bias voltage source for each succeeding divider stage may be synchronized with the outputs of the half frequency biasing source of the preceding stage by means of a pair oiconductors such as the conductors 59. It will be understood that the natural frequency ot the bias voltage source in each succeeding'stage will 'be half that of the bias voltage source in the preceding stage.-

In conformity with the arrangement shown for the initial stage I3, the next stage I4 is provided also with an indicating lamp 60 connected across the anode resistor of the tube 50; It will be understoodthat similar indicating lamps would be provided in the succeeding dividing counter g stages represented by the rectangle I0.

In addition to the visual indication provided by such indicating lamps, mechanism may also be provided for totalization and for printing the total counts by means oi' an adding machine with key operating coils controlled by voltages in suitable portions of the successive counter stages.

y For example, an arrangement such as that described in the copending application of Donaid L. Herr, Serial No. 415,268, tiled October 16, 1941,

- and assigned to the same assignee as tlie present application, may be employed.

As explained more in detail in the aforesaid Herr application the appropriate keys of an addlng machine may be actuated in response to en ergization of the successive counter stages through relays which may be of the electronic type taking the form of Thyratrons BI and 62 ior the stages I3k and Il with additional Thyratrons B22, B24 and so on for successive stages (not shown in detail). The Thyratron 6I has later the number of impulses o! alternating polarity produced by the generator II during the time .'interval from closing ot'the switch I2 to reopening thereof. After the switch I2 has been closed the tlrst positive impulse raises the potential oi the control electrode 21 of the tube 2l and causes current to be carried by that tube an odd numberoi impulses has been counted; in'

this case only one. The next impulse which would be a negative impulse raises the potential of the control electrode 2l of the tube 22 with respect to ground and causes the tube 22 to become conducting-shiitlng current away from the tube 2l. The lamp 31 again becomes luminous indieating that an even number of impulses has been its control electrode adapted to be connected across the cathode resistor BI' `oi' the tube 22 of the stage I3 and similarlythe Thyratron i2 has its control electrode adapted to be connected across the cathode resistor $2' of the tube!! in the counter stage Il. The additional Thyratrons are similarly connected in succeeding stages. For an arrangement in which half cycles or impulses oi each polarity arecounted instead of complete cycles a Thyratron (not shown) may be provided with a control electrode adapted to be connected across the cathode resistor 32. However, I shall explain the arrangement as used for counting complete cycles. An adding machine actuating coil 63 for the unit key is connected in the anodecathode circuit of the Thyratron 6l associated with the initial counter 'circuit I3. similarly a second adding machine actuating coil Il for the unit key is connected in the anode-cathode circuit oi the Thyratron 62 associated with the second counter stage I4, the rst divider stage. An adding machine actuating coil for the key number 2 would be associated with the next counter stage (second divider stage) and additional successive stages would be arranged to actuate keys for successively higher powers of 2,'viz: the numbers 4, 8, 16, 32, and so on.

parent that the counter circuits indicate or regcounted; in. this case 2. Each time either of the tubes 2i or 22 becomes conducting the other is rendered non-conducting because of the resistance cross coupling provided by the resistors S and I0. For example, when the tube 2i becomes conducting its anode potential falls as a result of the potentialdrop produced by current flowing through the anode resistor 30, which depresses the potential of the control electrode 2l of the tube 22 below the point of plate current cutoff. The voltage wave E: of the generator II may be of sine form, as shown in Fig. 2. However, owing to the fact that the Atubes 2i and 22 are alternately driven beyond plate current cutoil in one direction and to some fixed value in the conducting direction respectively, the output voltage E3 across the cathode resistor 32 is of square form, as shown in Fig. 3, rising to a constant value each positive half cycle of the `wave Ei, and falling to zero during each negative half cycle of the wave E2.

Since the bias voltage E4 for the tubes 39-and 40 in the counter stage Il is supplied by a half frequency multi-vibrator I8 synchronized with the original wave source Il, the voltage wave E4 will have half the frequency of the waves Ez and E3. As shown in Fg. 4 the wave E4 rises to a constant value during the rst complete cycle of the waves E2 and YE3 and falls to a constant negative value during the next complete cycle. Thus it alternates between positive and negative values during alternate complete cycles of E: and Es. The magnitude of the bias voltage E4 is suiiicient so that when the voltage E: is impressed on the control electrodes o! the tubes 39 and III one or the other of these tubes will become conducting according to which one has its control electrode potential raised. It will be apparent that since the cathodes of the tubes 39 and l0 are connected lo opposite ends 43A and 43B of the resistor 43,

. the bias potential of one tube will be increased sistance formed by the anoderesistors 4I and 42 considered in series will take the peculiar form of Es shown in Fig. 5. In drawing the voltage waves Eiy and E5 the points 43A and 53A, are considered as the positive ends of the resistors 43 and 53, respectively.

The voltage wave En alternates between positive and negativevalues but has half thefrequency oi the input waveiEa and the wave Ea. Its action upon the controlelectrodes of the tubes 49 and 50 of the divider stage I4 will be the same however as the action of the input voltage on the control electrodes of the tubes 2l and 2 2 of the initial stage I 3. Accordingly the output voltage En as shown in Fig. 6 will have a form similar to' the voltage E3 but half the frequency. The

output voltage of the next counter stage follow-` ing the stage Il would in turn have a frequency half that of the voltage Ee as represented by Fig. 7. Each succeeding stage would have an output voltage of similar wave form but with its' frequency each time divided by two.

Each time the tube 2| becomes conducting the lamp 31 is extinguished to indicate that an odd number of half cycles has been counted. Each time the tube 22 becomes conducting the lamp 31 becomes luminousto indicate that an integral number of complete cycles has been counted,

which is an even number of half-cycles.

Initially the lamps 31 and 60 and corresponding lamps in succeeding stages are luminous. When the tube 2l becomes conducting in Aresponse to the first half-cycle, the tube B9 of the stage I4 also becomes conducting; and the corresponding tubes of succeeding stages become conducting. Therefore,-the indicating lamps 31 and 80 and corresponding indicating lamps in succeeding stages allV are extinguished. The second half-cycle shifts current to the tube 22, illuminating only the lamp 31 and producing an indication of one complete cycle counted.

When the tube'2l again becomes conducting after passing through one complete cycle of operation, (i. e., uponthe third half-cycle) thetube 50 in the stage I4 also becomes conductingand the lamp 60 again becomes luminous. The lamp 60 remains luminous when the tube 22 next be comes conducting during the fourth half-cycle, and the lamp 31 becomes luminous. The illumination of both unit lamps 31 and 60 thus gives the indication that the total count of complete cycles includes the value two in the sum. The following time the tube 2| becomes conducting, current is shifted from the tube 50 to the tube 49; The lamp 60 is extinguished and an impulse is transmitted to the next stage. Simultaneously the indicating lamp (not shown) representing the numeral 2 of the next stage becomes illuminated. The next half cycle completing the third whole cycle, lights the lamp 31 but does not aect the ne'xt stage, leaving the. indication that the total count is three, since the unit lamp 31, and the numeral 2 lamp (not shown) are illuminated.

'I'hus, illumination of the indicating lamp 31 in the initial stage I3, indicates that the total count (invwhole cycles) is a sum including the value one or 2; illumination of the indicating lamp 60 in the first divider stage I4 also in-` dicates that the total count is a Vsum including the value one or 2; illumination of the indicating lamp (not shown) in the second divider stage (included in the rectangle I6 and not shown in detail) indicates that the total count is a sum including the value 2 or 21; illumination of the indicating lamps (not shown) in the succeeding divider stages I 6 indicates that the total count is 75 a sum including successively higher powers of two, viz: 4.122, 8=23, 16=2, etc.AAVV

In the arrangementillustrated it will be apparent that the control electrode of the thyra-l tron 6I would be energized upon every negative half cycle, i. e., with the'comple'tion of each cycle. and the control electrode oi the thyratron t2 would beenergized upon every second negative half cycle, i. e., every other cycle, and in the successive thyratrons (not shown) the control electrodes would be energized every fourth cycle; every eighth cycle, and so on, if the appropriate contacts of the rotary switch t5 were closed. When a registration is to be made the switch S5 is rotated and the appropriate thyratrons are energized according to the total count during the time interval.

It will be assumed that initially before the count is to be made each stage is in a condition with the lower tube, such as the tube 22, v'and the tube conducting, and the indicating lamps 31 and illuminated. In order to make sure that tion switches 32', QI', and sofon, may be provided in the cathode circuits'of the tubes 2l. 59,' and so on, respectively, for momentarily opening these circuits'before beginning` to make a count.

each counter stage will initially be in this condi- If the count is made in terms of impulses of A either` polarity or half cycles, it Will be seen that the initial stage I3 indicates unity or 2 vhalf cycles; the next stage I4 indicates 21, the following (not shown) 22 half cycles, and so on; whereas if the count is to be incomplete cycles or impulses of positive .polarity.only, -the indications of the initial stagecould be disregarded. and the iirst divider stage I4 indicates unity or 2 cycles, the next stage (not shown). indicates 21 cycles, and so on. i

I have herein shown and partially described -certain embodiments of my invention and certain methods of operation embraced therein for the purpose of explaining its practice and showing its application, but it will be obvious to those -skilled in the art that many modications and variations are possible, and I aim therefore to cover all such modifications and variations as fall within the scope of my invention which are dened in the appended claims.

What I claim as new and desire to secure Letters Patent of the United States is:

l. A counter comprising in combination a pair of electric discharge devices each including `an anode, a cathode and a control electrode, input terminals adapted to have electrical impulses to be counted applied thereto, connections between said terminals and said control electrodes for applying said impulses to said control electrodes with opposite polarities, one of said discharge devices having a resistor connected in series with its cathode, connections for Vcoupling the control electrode of each discharge device to the anode of the other, a source of anode voltage and anode resistors interposed between the voltage in the control electrode circuits o! said secondmentioned pair oi' discharge devices with opposite polarities, a third pair of electric discharge devices each having an anode, a cathode and a control electrode with cross coupling between the control electrodes and anodes. and a coupling between the anode of one t the second-mentioned electric discharge devices and the control electrodes of said third pair oi electric discharge devices. Y

2. A counter comprising in combination an initial stage and one or more divider stages,- the initial stage including a pair of electric discharge devices, and input terminals with connections for shifting current from one discharge device to another alternately in response to successive impulses supplied to said input terminals, each divider stage including input terminals with connections to the anode-cathode circuit oi' one of the discharge devices of the preceding stage, a

pair of inversion electric discharge devices each having an anode, a' cathode and a control electrode. the control electrodes being connected to the divider input terminals, a device with synchronizing conductors adapted to be connected to a source synchronized with the input terminals of the initial stage for rendering said inverf sion discharge devices alternately responsive to impulses applied to theinput terminals of the divider stage, and a second pair of electric disv charge devices each having an anode, a cathode and a control electrode with coupling between the control electrodes and the anode-cathode circuit oi' one of the inversion discharge devices for shifting current back and forth between electric discharge devices of the latter pair alternately in response to successive impulses transferred from said one of the inversion discharge devices through said coupling.

3. In combination, a pair of electric discharge devices'with control electrodes and cross-couplings between the discharge devices for maintaining each discharge device in-a condition of conductivity determined by the current dow condition of the other to produce two relatively stable conductivity conditions, in one oi which the ilrst tube has' greater conductivity and the second tube has less conductivity and in the other of which the relative conductivities are reversed.

connections for applying input impulses to said control electrodes for shifting the greater conductivity condition from one discharge device to the other, and means included in such connections for inverting the polarity of alternate impulses oi' predetermined polarity comprising a second pair of electrode controlled electric discharge devices having their output circuits connected to the control electrodes of said nrst pair of electric discharge devices, their control electrodes connected in parallel to the impulse source, and their input circuits connected across an a1- ternating current source oi' one-half the trequency of the impulse source.

ELLSWORTH D. COOK.

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