US2490243A - Electronic cycle counting circuit - Google Patents

Description

Dec. 6, 1949 J, C, TELUER 2,490,243

ELECTRONIC CYCLE CUNTING CIRCUIT Filed June 12, 1947 2456/" y as Ailf-`@f WMI/96m Patented Dec. 6, 1949 UNI-reo STATES lairrelsir` oFF-ice Joseph C. Tellier, Penn Wynne, Pa., assignor to Philco. Corporatiom Philadelphia, Pa., a corpolation of Pennsylvania Application Junev 12, 1947, Serial No. 754,196'

3 Claims. 1.

Thisv invention relates to circuits for counting the cycles ofa periodic voltage, and has for its principal object the provision of a no vel circuit for the stated purpose. The present application is a continuation-impart of application Serial l No. 566,739-, abandoned'.

Prior circuits designedy and adapted to accom plish the general purposev above-stated are cornmonly characterized in that they count the cyclesv ofl a periodic voltage byy adding voltages producedv in response to the successive cycles of the appliedk voltage, and by'triggering an indieating circuit( when, the resultant or summation voltage reaches a certain magnitude or value. Such devices have been subject to error due to variationsy orA changesv in the circuit components, such as resistors, which are employed, and due also to variation of; thesignal or voltage under filed December 5, 1944 now observation. Thus variationsor changes in bias, 1

triggering level, signal voltageetc. may produce afalse count of the cycles and thus give rise to error.

One object of the present invention is to provide a cycle counting circuit which is free of such objections ofgprior devices of this general class.

Another object'l of; the invention is to provide anovel cycle counting circuitiwhichcounts the cycles of a periodic voltage directly rather than by summing vonageproduedinresponse t0 Successive cycles.

A further object of the invention is to provide a cycle counting oirvcuitwhich effectively counts the number of timesaperiodio voltage reaches its maxin'mrrr value andnthus accurately counts the cycles thereof.

The invention mayl be clearly understood by reference to the accompanying drawing, in

which:

Fig. 1 is a diagrammatic illustration of a prevferred form of the invention; Vand Fig. 2 illustrates one form of periodic `vvave for purposes of expllarviat. m.l

Referring to Fig. 1Y of the drawing, there is represented at E a source of a periodic voltage 'whose cycles are tobe counted; Connected to the source E is the novel-circuit of the present invention, which comprises a plurality of seriesconnected energy-storing devices which preferably take the form of capacitors designated C1, C2, C3 and C4 respectively. While four capacitors are shown in the specic illustration, the number may be varied, as will be apparent later. The circuit further comprises a corresponding plurality of shunt-connected unilateral conducting devices which preferably take the form of diodes designated D1, D2, D3, and D4 respectively. These unilateral conducting devices are connected respectively to the output sides of the energystoring devices or capacitors. Moreover, consecutive ones of the unilateral conducting devices, or diodes, are connected in reverse conducting relation to their associated or corresponding. energy-storing devices. Thus the iirst diode D; has its anode connected to the output side of the iirst capacitor C1., the secondy diode D2 has its cathode connected to the output side of the second capacitor C2, and soon. The reason 'for this reverse connection of 'the consecutive diodes vv-ill be apparent presently. Preferably the source E and the diodes are connected to ground as illustrated, so that one side of the source and one of the electrodes of each diode are maintained at a Xed (ground) potential.

In operation, the circuit effectively counts the number of times the voltage of source E reaches its maximum value. This counting function is accomplished through a mode of operation in which the series ofA capacitors, C1, C2, C3, and Cgare successively charged, each succeeding capacitor receiving its charge from a preceding capacitor each time the applied voltage alternates from one maximum value to the other. For simplicity, it may be assumed that the voltage of source E is a simplesine wave W, as shown in Fig. 2, which varies from 0 to 20 volts. Assume further that all of the capacitors or condensers are initially discharged When the periodic voltage of source E is applied to the input of the circuit, and that the capacity values of the capacitors` are such that, in operation, each succeeding capacitor is chargedV to approximately the full input voltage without substantially reducing the charge on the preceding capacitor. This may vbe accomplished by making the capacity of each succeeding capacitor substantially smaller than 'the capacity of the immediately preceding capacitor. Under these conditions the operation of the system is as follows:

As the input voltage increasesl from 0 to- +20 volts during time t1, the condenser Ci is charged to approximately the full 20' volts' through its associated diode Di. Since the voltage at point 1 cannot go positive, no further operation occurs during the increase of the applied voltage.

As the applied voltage decreases from its maximum positive value to its maximum negative value. during time tz, the voltage at point l decreases to -40 because of the voltage across condenser C1, and at the same time, the condenser Cz is charged through its associated diode Dz and the condenser C1. At this time the diode D1 is non-conductive. Since point 2 cannot go negative, no further operation occurs during the decrease of the applied voltage.

As'the applied voltage again increases to |20 volts during time ta,'the voltage at point I increases to 0, andthe Voltage at point 2 is increased to +40 volts due to the voltage drop across condenser Cz. During this portion of the cycle, the diode D1 is blocked by the back Voltage across condenser C1, and of course the diode Dz is non-conductive. The diode D3, however, is conductive, and condenser C3 is charged through this diode. Since point 3 cannot go positive, no further operation occurs during this portion of the wave cycle.

When the applied voltage again decreases from i its maximum positive value to its maximum negative value during time t4, the Voltage at point I decreases to -40 volts, the voltage at point 2 decreases to 0, and the voltage at point 3 is decreased to -40 volts by the voltage drop across condenser Cs. At the saine time the condenser C4 is charged through its associated diode D4, the other diodes being non-conductive. As the applied voltage again increases during t5, an output voltage appears at point 4, which indicates that two cycles of the applied voltage wave have elapsed. The output voltage may be applied to any speciiic use. While thepresent invention is not concerned with the particular use to which the circuit may be applied, it may be noted that the circuit may be used as a timer, or as a frequency divider. For example, it may be used to cause operation of another circuit after a certain number ofV cycles of the applied voltage have elapsed.

It will be noted that the operation of the circuit involves successive charging of the condensers or capacitors in response to successive portions of the applied voltage until an output voltage appears after a certain number of cycles have elaps-ed, depending upon the number of capacitors and associated diodes. It will also be noted that each succeeding pair of capacitors and their associated diodes vconstitute a stage which responds to one cycle of the applied Voltage. Thus the circuit comprises a plurality of cascaded stages, which respond in succession tofsuccessive cycles of the applied voltage. Within practical limits the number of such stages may be varied at will so as to vary the number of cycles which are counted during a complete operation of a circuit.

f While the circuit of Fig. 1 has been described with reference to the sine wave of Fig. 2, it is capable of counting the cycles of any periodic voltage, such as a pulse signal, a square wave, a saw-tooth Wave, etc. In any case, the circuit operates in the manner above described, the condensers being successivelyfcharged in response -to periodic increase and decrease of the applied voltage.

When circuits constructed in accordance with the principles of the present invention comprise a large number .of cascaded stages, it may be 4 impractical to make the capacity of each succeeding capacitor substantially smaller than that of the preceding one, due to the great range of capacitance values which would then result. Under these circumstances the capacitance val ues of the condensers are preferably equal. A typical capacitance value under these conditions is 1,000 micro-microfa-rads, butI the value employed may be selected according to the particular application of the invention in any instance.

. 'In any case, the circuit constants should be such that the capacitors are not discharged by leakage during the counting operation su'iciently to interfere with the operation. If desired, suitable resistors may be shunted across the capacitors so as to discharge each capacitor after a desired time.

Where the'capac'itors C1, C2, etc. are of substantially equal value the operation of the system does not follow precisely the description outlined above. However the circuit `has the same cycle counting properties, the chief distinction. being that the output voltage is decreased approximately in inverse ratio to the number of condensers in the circuit.

Although the invention has been described with reference to the illustrated embodiment, it is not limited Vthereto but is capable of various mod ications within the scope of the append-ed claims.

I claim: l

l. A cycle counting circuit comprising, in com# bination, irst and second input terminals, rst and second output terminals, the second of said input terminals and the second .of said output terminals being connected to a point of vixed potential; a source of periodicvoltage whose cy-` cles are to be counted, said source being connected to said input terminals; a pluralityof energy storing devices connected in series between the rst of 4said input terminals and the rst of said output terminals, there being junctions between said devices; and a corresponding plurality of unilateral'conducting devices, one of said unilateral conducting devices being connected between said first and second output ter. minals, the remaining unilateral conducting de# vices being connected, respectively, between said junctions and said point. of xed potential, consecutive ones of said unilateral conducting devices being mutually reversed 'so as to be conf ductive in opposite directions. y

2. A cycle counting circuit according to claim 1, wherein said energy storing devices lare capaci'l tors.

3. A cycle countingcircuit according to claim 1, wherein said unilateral conducting devices are space discharge devices, each having an anode anda cathode.

JOSEPH C. TELLIER.

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

UNITED STATES PATENTS Number AName l. v. Date 2,336,768 SX et al. DBC. 14, 1943 2,394,389 LOId Feb. 5. 1946A

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