US2822471A - Pulse counting circuit - Google Patents

Description

Feb. 4, 1958 H. L. FOOTE 2,822,471

PULSE COUNTING CIRCUIT Filed Sept. 26, 1955 A 22 23 To IDENTICAL SUCCEEDING STAGES REGlgTER REGISTER LAMP LAMP sTAeE STAGE 2 INVENTOR. HOWARD L. FOOTE ATTORNE" United States Patent PULSE COUNTING CIRCUIT Howard L. Foote, Fairport, N. Y., assignor to General Dynamics Corporation, a corporation of Delaware Application September 26, 1955, Serial No. 536,338 1 Claim. (Cl. 250-27) The present invention relates to electronic circuits for counting electrical pulses.

It is a principal object of this invention to provide an improved scale of two pulse dividing circuits of extreme simplicity and using inexpensive components.

It is also an object of this invention to provide a simplified binary counting system having a plurality of serially connected improved and simplified scale of two pulse dividing circuits.

A feature of the invention is the use of a very simple two-element gaseous discharge device in a scale of two pulse dividing circuit and also the use of another one of the same type of two-element gaseous discharge device as a coupling unit to serially connect each scale of two pulse dividing circuit as a binary counting system.

Further objects, features, and the attending advantages of the invention will be apparent with reference to the following specification and drawing in which the sole figure thereof is a schematic diagram of a binary counting system employing two serially connected scale of two pulse dividing circuits according to the invention. In the drawing, the circuit is arranged to be operated from a source of direct current potential of suitable voltage (not shown) and the positive and negative symbols enclosed in brackets are intended to denote the respective terminals of such power supply. The circuit employs a very simple type of two-element gaseous discharge device such as shown at 11-14. For purposes of this description, each of the gaseous discharge devices 11-44 may be a neon lamp such as that known under the designation NE-96. The operating characteristics of such neon lamps are well known and it is known, for example, that the minimum voltage for sustaining a conductive discharge in an NE-96 type lamp is about 70 volts and that the minimum voltage for firing and initiating a conductive discharge in the-same type of neon lamp is about 135 volts.

As shown in the drawing, two scale of two pulse dividing circuits are serially connected to form a binary counting system and each stage includes a register lamp such as the register lamp 11 for stage 1, or the register lamp 13 for stage 2, and a coupling lamp such as the coupling lamp 12 between stage 1 and stage 2, and the coupling lamp 14 from stage 2 to a succeeding scale of two stage or output terminals. One electrode of each of the register lamps 11 or 13 is connected in series with an associated resistance 15 or 17, respectively, to the positive terminal of the power supply. The other electrode of each register lamp 11 or 13 is connected to the other or negative terminal of the power supply. The voltage of the power supply and the size of the resistance 15 or 17 are chosen to normally provide a potential difference across each register lamp 11 or 13 greater than 70 volts but less than 135 so that normally each register lamp 11 or 13 is not conductive, but once a conductive discharge has been initiated will remain conductive until otherwise extinguished.

Assuming the register lamp 13 to be non-conductive,

a first pulse to be divided or counted is connected across the input terminals 18 and 19 with a polarity such that after differentiation and sharpening by the resistance condenser differentiation network including resistors 20, 21 and condensers 22, 23 it will add to the voltage normally across the first register lamp 11 to raise such voltage beyond the initial firing potential and cause lamp 11 to fire. The second pulse to be divided or counted as thereafter applied across the input terminals 13, 19 while the register lamp 11 is conducting, will not add to the voltage appearing across the register lamp 11 due to the constant current characteristic of such gaseous discharge glow lamp while it is conducting. However, condenser 23 is charged by such second pulse and at the end of the pulse, condenser 23 must discharge through resistor 21. As the condenser 23 discharges, it provides an additional current path from the direct current source through the resistor 15 connected in series with the register lamp 11 and the additional voltage drop across such resistance lowers the voltage across the register lamp 11 below the minimum sustaining voltage of 70 volts and extinguishes the lamp. Thereafter, a third pulse applied across the input terminals 18 and 19 will operate in the same manner as the first pulse and add to the voltage across register lamp 11 causing such register lamp to again be fired. Thus it will be seen that the continued action of the circuit including the register lamp 11, load resistance 15, coupling condenser 23, and condenser discharge resistor 21 results in a scale of two pulse dividing action since the register lamp 11 is alternately fired and extinguished by successive input pulses. It is only necessary to provide a pulse output as determined by the conducting or non-conducting condition of the register lamp 11 to obtain a scale of two divided pulse output or, in other words, one pulse out for each two pulses in.

According to the invention, a coupling lamp 12 is connected in series with a discharge resistance 24 in a circuit in parallel with the register lamp 11. The constants of the resistance 15, neon glow lamp 12, and dis charge resistance 24 are selected such that the glow lamp 12 is normally non-conducting but will be fired at the interval that the voltageacross the register lamp 11 is raised by an input pulse to initially fire the register lamp 11. However, the value of the discharge resistance 24 in series with the coupling lamp 12 prevents the maintaining of a conductive discharge through the coupling lamp 12 at the end of the applied pulse that raised the voltage across the register lamp 11. Thereafter, whenever a pulse is applied across the register lamp 11 at a time when the register lamp 11 is not initially conductive, both the register lamp 11 and the coupling lamp 12 will be fired although the coupling lamp 12 will only continue to be fired for the pulse duration due to the afore: mentioned discharge resistance 24. While the coupling lamp 12 is conducting, a pulse is produced thereby and connected across coupling condensers 25 and 26 to raise the voltage across the register lamp 13 of stage 2 and tire such register lamp. The action, of course, continues to cause the coupling lamp 14 to become conductive and apply a pulse to the register lamp of the next succeeding stage, and so long as any of the register lamps of successive stages are not conducting at the time that the pulse is applied they will, in response to the pulse, be made conductive along with their associated coupling lamps. Attention is called to the discharge resistance 28 for obtaining the discharge of the coupling condenser 26 when such condenser becomes charged by a pulse applied at a time when the register lamp 13 is conducting as was previously described in connection with the first stage register lamp 11.

The operation of the binary counting system employing a plurality of serially connected scale of two pulse dividing circuits of the invention is as follows. It will be assumed that none of the register lamps 11, 13, etc., .of each stage, or the coupling lamps 12, 14, etc., between respective :stage's, are conductive. A first pulse applied across the input terminals 18 'and 19 causes each register lamp 11, 13, etc., and the associated coupling lamps 12, 14, etc., to be fired and become conductive during the duration of the pulse. At the end of the pulse, the coupling lamps 12, 14, etc., are extinguished but the register lamps ll, 13, etc., remain fired in their conductive condition since the normal voltage connected across each registerrlamp is of sutficient value to maintain a conductive discharge while the normal voltage across the coupling lamps 12 and 14 is of insuflicient value to maintain a conductive discharge. Now assuming that each register lamp is initially fired, the first pulse applied across the input terminals 18 and 19 will extinguish the register lamp and the coupling lamp 12 will not be fired so that no pulse is transmitted to the register lamp of the second stage. The next pulse applied across the input terminals 18 and 19 will now be applied at the time when the register lamp 11 is extinguished and will cause register lamp 11 to fire and at the same time fire the coupling lamp 12 for the duration of the pulse. The firing of the coupling lamp 12, therefore, applies a pulse across the register lamp 13 of the second stage which at that time was conductive so that such register lamp 13 will be extinguished at the end of the pulse due to the discharge action of the condenser 26 and the discharge resistor 28. The next pulse applied across input terminals 18 and 19 will again extinguish the register lamp of stage 1 and, of course, the coupling lamp 12 does not fire so that the register lamp 13 of stage 2 remains extinguished. This action continues through as many of the scale of two pulse dividing stages as may be provided. For example, the following table will show the operated condition of the register lamps for each stage of a four stage binary counting system in response to the first sixteen pulses applied thereto, it being assumed that all of the register lamps 11-13 of each stage were initially fired.

Stage 1 2 3 4 It should be obvious that the principles of the invention may be used with any form of two-element gaseous discharge device of the type having a minimum voltage for sustaining a conductive discharge and a second higher minimum voltage for initiating a conductive discharge, and that, therefore, the invention is not limited to its use with the neon type of lamps as described. Various modifications may be made within the spirit of the invention and the scope of the appended claim.

What is claimed is:

A binary counting system comprising a plurality of binary stages, each of said binary stages having a register gaseous discharge device connected in series with a .resister to a source of direct current, the voltage supplied by said direct current source across the register device of each stage being normally of insufficient value to initially fire the register device but of suflicient value to maintain a conductive discharge once the register device has been fired, a source of pulses to be counted, an input condenser for coupling pulses to be counted to the junction between the resistor and the register device of the first binary. stage in such manner as to raise the voltage across the register device of the first stage to fire said first register device when a pulse is coupled thereto if the register device is non-conductive and to extinguish the register device when a pulse is coupled thereto if the register device is conductive, a coupling. gaseous discharge device connected in series with a coupling condenser between the junction of the resistor and register device of each preced ing binary stage to the junction of the resistor and register device of the next succeeding binary stage, and a bleeder resistance connected between the junction of the coupling device with the condenser and a terminal of the source of direct current to prevent the maintaining of a discharge through the associated coupling device for longer than a pulse interval, the value of the bleeder resistance and the constants of the coupling device being such that said coupling device will discharge to conduct a pulse to the succeeding binary stage only when a pulse is applied to the register device of the preceding binary stage if such register device is non-conductive.

References Cited in the file of this patent UNITED STATES PATENTS 2,631,194 Reeves Mar. 10, 1953 2,646,534 Manley July 21, 1953 2,665,068 Williams Jan. 5, 1954 2,730,658 Six Jan. 10, 1956 2,739,235 Vande Sande Mar. 20, 1956 OTHER REFERENCES Electronics, April 1953, pp. 248, 250, Neon Lamp Flip- Flop and Binary Counter, Vuylsteke.

U. 5. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent Non 2,822,471 February 4, 1958 Howard Lo Foote It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Let oers Patent should read as corrected below.

Column 3 after the table, insert the following key:

denotes lamp extinguished @3- denotes lamp fired Signed and sealed this 25th day of March 3.958

SFAL 1tesz KARL Ho AXLINE ROBERT C. WATSON Atteeting Officer Commissioner of Patents U. S. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,822 4'7l February 4, 1958 Howard L Foote It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, after the table, insert the following key:

denotes lamp extinguished. denotes lamp fired Signed and sealed this 25th day of March 1958,,

KARL Ho ABQINE ROBERT C. WATSON Attesting Officer Comnissioner of Patents

Images