US1869500A

US1869500A - Relaxation circuit oscillator

Info

Publication number: US1869500A
Application number: US427622A
Authority: US
Inventors: Robert M Page
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-02-11
Filing date: 1930-02-11
Publication date: 1932-08-02
Anticipated expiration: 1949-08-02

Description

RM. @mi RELAXATION CIRCUIT" OSCILLATOR 11, 195o 5 sheets-sheet 1l Filed Feb.

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ATTORNEY www@ M. PAGE (y RELAXATION CIRCUIT OSCLLATOR Fild Feb.

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Filed Feb. l1, 1950 3 Sheets-Sheet 5 011/5 CYCZE fafa! Aval,n Za Ze @wat jaar cJcZe n j :f o, a if @M ru -Am/ n f 7m l; p L |k ,0- l` IN V EN TOR.

ROM/K 9%, $415@ ATTORNEY 'r Patented Aug. 2, 1932 i Y i y if Aunirsi) 1 srnrss' PATENT' iloFFicr.-

:ROBERT Kraemer;wasmieroii, Drsrrticr or COLUMBIA nnAxnfri-on CIRCUIT 'oscILLA'roa l j Application mearebr'uaryin, 1930. serial No."427,622. My invention relates broadly to high fre` planatory diagram showing the equivalent quency oscillation generators and more parcondenserl circuit :duringtlie charging porticularly to a relaxation oscillation circuit. tion `of the cycle; Fig. 9 is a reproduction of One of the objects of my invention isV to an oscillograin of the oscillator of my iiivenprovide a circuit arrangement for a relaxa-` tion showing a condition especially favorable 5.. tion oscillation system having means for con- .toI frequency multiplication in the ratio of trolling the rati-o of charging time tov disl4:2 to 1; and Fig.10 shows the reproduction charge time in the condenser circuit associof anoscillogram of the circuit of my invenated with the oscillation system. -tionl arranged to operate with a multiplica- 10 Another object of my invention is to protion ratioof 2 to 1. e0 vide a relaxation circuit oscillator with In my study of relaxation circuit osciliiieans for selecting and fixing the period of latorsfor Vfrequency division at high frecharging t'me of the condenser system asque'ncies, I have found that in circuits heresociated with the oscillator with respect to tofore known that the period of oscillationV the period of discharge time for securingy is unequally divided between the charging 65 oscillations of v predetermined .frequencyy time andthe discharging time of the con- `which are highly stablefin character. denser in the relaxation circuit, the charging A further object of my invention is to protime being much less than the discharge time. vide a circut arrangement for a screen grip This unequaldivision oftime period results `typeof electron tube relaxation circuit osin relatively poor operation of the relaxation cillator having means in circuit with the eleccircuit oscillator for certain purposes.

trode of the electr-on tubesystem for adjust-A I have found that for the best results in ingthe ratio of charging time ofthe confrequency division at' relativelyhigh fredenser circuit associated with the relaxation quencies' and for certain other purposes, conl i oscfllator system with respect to discharging siderable' improvement results when the 75 time thereof. j j Y. charging time of the condenser in" the relaxal Stillanother object of my invention is to tion circuit is made equal'to thedischarge provide a relaxation circuit arrangement for time, or where the charging time bears some i a multiple ,grid electron tube system lwith deiinite'and controllable relation to the dis- 30 means connected to selected gridsfor regucharging time. -Inorder to control the ratio 80 lating the discharge time of the condenser of charging .time to discharging time, I prosystem with respect to .the charging time of vide a circuit arrangement for a. relaxation thecondenser system. circuit oscillator wherein a resistance is in- Other and further objects of my invention troduced in circuit with the condenser in the will be understood from the specification relaxation circuit, or inv circuit with some hereinafter following by reference to the-acone of the electrodes of ya multiple electron compa-nying drawings, in which: j tube used in the circuit, the resistance being Figure 1 diagrammaticallyshows the cirfixed or variable and in -such location and cuit arrangement -of my inventionapplied to value in thev circuit that the ratio of charging a screen grid relaxation oscillator; Fig. 2 time to discharging time may be adjusted by shows a modiiied circuit arrangement for the selecting the value of the resistance. The

relaxation oscillator of my invention; Fig. entire output of the oscillator can be concen- 3 shows a stillr further modified circuit for trated into any desired time division irre- 'the relaxation oscillator of my invention; spectiveof the frequency of oscillations. j r[he 95 Fig. 4 shows another modification of the reresistance member also tends to stabilize the laxation circuit oscillator of my invention; operation of the ,relaxation circuit oscillator Figs. 5, 6 and 7 show modifications of the rewhich is essential when the oscillator is used j laxation circuit of my invention employing for frequency division and synchronization 50 multiple grid electron tubes; Fig. 8 is an exwork. I employ the principles of my invenino riodic electromotive force.

' higherfrequencies. The improvement resulttion in multiple grid electron tubeucircuits as will be hereinafter pointed out 1n detail.

In the relaxation oscillator, the oscillations consist of aperiodic pulses of electromotive force occurring in cyclic order, and the outut is not necessarily of sine wave form. The requency of a relaxation oscillator may be controlled by a submultiple of another perelaxation oscillator, an electron vtube with two grids is .used with resistance and ca acity only. Such an oscillator is described 1n the Van der Pol Patent 1,744,935, dated January 28, 1930. The fact that in thel relaxation oscillator the output frequencywhile of considerable amplitude, can be controlled by a higher frequency of extremely small amplitude, has sug ested its use for frequency division.

Suc frequency division is possible in ratios `up to several hundred to one. Attemptsl to thus employ relaxation oscillators heretofore known, have however shown them to drift in discrete steps from one submultiple 'frequency of the input to another while in operation, remaining on one step for only a relatively short time. In the system of my invention these undesirable operating characteristics' are avoided and stable operation in frequency' division is obtained.

The fundamental frequency of the relaxation oscillator is equal to the' output frequency, and the working range of frequency may extend from the vlowest frequenciesto 100 kilocycles, of even to 200 or 30() kilocycles. The relaxation oscillator can however be controlled by frequencies up to several thousand kilocycles by utilizing sub-multiples of these ing from the circuits which are here described are particularly marked at frequencies above 500 cycles, and up to 100 kilocycles or more.

In Figure 1, the electron tube employing i the principles of my invention has been designated by reference character 1 including cathode 2, inner grid 3, outer or screen grid 4, and plate electrode 5. The relaxation cir- 'cuit is -shown completed through high potential vsource 6 which connects at the posioscillator are completed throughcondenser 1 11 and resistance 12, which in Fig. 1, have been shown connected in series and connected Vbetween the inner grid 3 and the outer or screen; grid 4. The cathode 2 is heated byany suitable source such as battery 14.

In Figf2, I have shown the relaxation circuit oscillator as including the several ele- In one form ofl ments shown in Fig. 1 but the condenser circuit is rearranged so that the condenser 11 has one side 11a thereof connected directly to the -inner-grid 3 while the other side 11b. thereof connects to the outer lor screen grid 4 through the resistance 12 arranged in series' between the outer or screen grid 4, and the resistance 8. The inner grid 3 connects through resistance 9 with a point of positive potential in battery source 6 as indicated by reference character 10 in a manner similar to the arrangement described in Fig. 1.

In Fi 3 I have shown a modified arrangement o the relaxation oscillator circuit in which the circuit including condenser 11 is completed by a connection between the terminal 11a of the condenser and the inner grid 3, while the terminal 11b of the condenser connects through resistance 12 with the outer or screen grid 4.

In Fig. 4 I have illustrated an arrangement of relaxation circuit wherein the condenser 11 is shunte'd by the resistance 12 and the shunted circuit thus formed connected between the inner grid 3 and the outer or screen grid 4.

v In Figs. 5,6 and 7, I have shown various in the relaxation oscillator can be controlled.

A three grid'tube is shown -in Fig. 5 designated at 15 including cathode 16, plate electrode arrangements of the elements in the relaxai 17, and

grid electrodes

18, 19 and 20, respeci tively. The external circuits for the oscillator include resistance 21 in circuit between inner grid electrode 18 and one side of cathode 16. Resistance 22 connects between outer grid electrode 2O and the negative side of the high potential source 23. The relaxation circuit is completed through lcondenser 24 and series connected resistance 25 connected between oute grid electrodel 2O and grid electrode 19. Resistance 26is disposed between intermediate grid electrode 19 and a point of positive polarity 27 in battery source 23. The plate electrode 17 is connected to a point of high positive polarity on potential source 23 as indicated. y

In Fig. 6 I have shown a modified arrangement of the relaxation circuitof Fig.`5 whereinthe resistance 25 is disposed directly in series with grid electrode 2O and in series with resistance 22, returning to the negative side of battery 23 through lead 29. The condenser 24 conncctsbetween one end of the resistance 25 adjacent the end of resistance 22 and the other side of the condenser connects to grid electrode 19. The grid electrode connects through resistance 26, with the positive potential point 27 of high potential source 23.

The plate electrode 17 connects to a point of positive polarity on battery source 6 as indicated; l

In Fig. 7, resistance 25 is directly connected in shunt with condenser 24 and the shunt circuitthus formed connected between grid electrode 19 and grid electrode 20. The remaining parts of the circuit are similar to those described with reference to Fi s. and 6.

The relaxation circuit oscil ator of my invention may have the resistance 12 disposed as has been described in different relationsistance may be variablev for' selecting that value which enables the charging time to be` controlled with respect to the disch arge time. In this manner the output of the oscillator on any desired harmomc may be increased and relatively high efliciency obtained. The influence of the resistance in the control circuit is that a relatively high degrceof stability in the operation of the relaxation circuit oscillator is'obtained.

The operation ofthe-'circuit of my invention may be described as follows, with reference to Fig. 1, assuming that resistor 12 is omitted:

The voltage-on the condenser is equal .to y

the diEerence between inner grid and o uter grid voltages. The inner grid voltage is the impressed battery voltage less the resistance drop through 9. The outer' grid'voltage is merely the resistance vdrop through 8.' Suppose the cathode to be deenergized.` Thecondenser voltage will thenassumea value equal to that of the portion of battery connected between cathode and the inner grid connection 10. Now letthe cathodebe energized. The high inner grid current that follows will reduce the positive -potential at 3 to only a fraction of its initial value, causing the condenser todischarge. The discharge current through 8 causes a high negative potential at 4 which potential decreases as the discharge current decreases. As the potential at 4'approaches filament potential it reaches the value at which plate current begins to flow and inner grid current is decreased. The accompanying increase in positive potential at 3 causes the condenser to beginto charge,-

the charging current throughS .putting the potential at 4 at a positive value. By virtue of the positive pot-entialthusplaced on the outer grid, the inner grid current is vfurther reduced and therefore Vthe potential at 3 is further increased so that the condenser is caused to charge at a higher rate. The resulting -hig'h charging current through 8 causes a very high positive potential at.4 which now decreases as the' condenser becomes charged and the char ing current decreases. As the outer potential approaches cathode potential now .from the positive direction, it reaches the value at which plate current is reduced and inner gridcurrent increased. The resulting decrease in potential at 3 soon causes the condenser to discharge, the high discharge current through 8 causing a high negative potential at 4, and the cycle is repeated. The tube works continuously on saturation current considering the sum of the currents in the leads lto plate 5through resistor 8 and through resistor 9, and the shifts in inner grid voltage from one extreme to the other may be considered to take place instantaneously.

.As 'showny 'in Fig. 8,- the condenser is charged' through the external and internal resistances of the outer grid in parallel. This external resistance being of the order of 100,000 to 200,000 ohms, is. much greater than the internal resistan :ers during the charging portion of the cycle, when the outer'grid is positive. The condenser therefore becomes charged very quickly through the comparatively low internal resistance. During the discharge portion of the'cycle, however, the internal resistance to the reverse current is of the order of megohms, and the condenser discharges more slowly through the external resistance. Consequently, the discharge period of the condenser and

resistances

8 and 9 in series, constitutes the major portion of the period of oscillations in the circuit. These oscillations are stable and satisfactory for frequency division and the other purposes heretofore mentioned.

The oscillations obtained with the circuit ofFig. 1 but-with series resistance 12 omitted are shown by the oscillogram of Fig. 9. The plate voltage is shown at a, the inner grid voltage at b, and the outer grid voltage at c' P and P represent the critical voltages of the outer grid, at which the direction of condenser current is reversed. This oscillogram representsa condition especially favorable to frequency multiplication in the ratio of,

42 to 1. For facilitating the study of the operation or for other purposes, the charging period may be lengthened with respect to the discharge period. In the circuit of Fig. 1, this is accomplished by inserting a resistance l2 of suitable value directly in series with condenser 11. vThe new wave form so produced is shown by the oscillogram of Fig. 10, .wherein the reference characters correspond-to those of Fig. 9. The insertion of this resistance is seen to speed up the discharge and slow up the charge, thus operating toequalize the two parts of the cycle.

, Fig. 10 represents a condition especially favorable to frequency multiplication in the ratio of 2 to 1. Conditions favorable to desired ratios of frequency multiplication may 1. In a relaxation circuit oscillator, an electron tube.including a cathode, a plate and a multiplicity of grid electrodes, an input circuit connected between said cathode and one of said rids, an output circuit connected to said anoy e, said circuits including impedance elements substantially free of inductive characteristics, and a circuit disposedbetween two of said grid electrodes and including an impedance element substantially .free Aof' in dnctive characteristics and a condenser, said impedance element operating to adjust the charging period of said condenser with respect to the discharge period thereof.

2. In a relaxation oscillator, an electron tube including a cathod-e, a plate and a plurality of grid electrodes, means for maintaining one of said grid electrodes and said plate electrode at different values of positive potential, an input circuit connected between said cathode and one of said grids, an output circuit connected to said anode, said circuits including impedance elements substantially free of inductive characteristics, and a circuit including a condenser and a resistance disposed between two of said grid electrodes, said resistance operating to control the charging period of said condenser with respect to the discharging period thereof.

3. In a relaxation circuit oscillator, an electron tube including a cathode, a plate and a. plurality of grid electrodes, nieans tor maintaining said plate electrode and one of said grid electrodes at different values of positive potential, iinpedances disposed in the external circuits of said oscillator, said ilnpedances being substantially free of inductive characteristics, and a circuit including a condenser and a resistance connected between the grid electrode which is maintained at positive p ential and another of said grid electrodcs,fsa1d resistance operating tocontrol the'charging period of said condenser with respect to the discharging period thereof.

4. A relaxation circuit oscillator comprising an electron tube including a cathode, a plurality of grid electrodes and a plate electrode, an input circuitconnected between said cathode and one oi." said grids, an output circuit connected to said anode, said circuits being substantially tree of inductive eiicets, a source of potential for impressing a positive bias on one ot said grid electrodes and a larger positive bias on said plate electrode` and a circuit inter-connecting two of said grid electrodes and including a condenser and a resistance in series, said resistance 0perating tocontrol the charging period of said condenser with respect to the discharging period thereof.

5. In a relaxation oscillator, an electron tube having cathode, inner grid, outer grid,

and anode, a resistor connected between said outer grid, and said cathode, a source of potential connected between said cathode and said inner grid, a second source of 'potential connected between said inner grid and said anode, and a condenser and a second resistor connected in series between said-inner grid and said outer grid. f

6.In a` relaxation oscillator, an electron tube having cathode, inner grid, outer grid and anode, a .pair-ot resistors connected in series between said outer grid and said cathode,

a source of potential connected between said cathode and said innergrid, a. second source of potential connected between said inner grid and said anode, and a condenser connected between said inner grid and the common connection connecting said two resistors in series.

7. In a relaxation oscillator, an electron tube having cathode, inner grid, outer grid, aud anode, a resistor connected between said outer grid and said cathode, a source of potential connected between said cathode and said inner grid. a second source of potential connected between said inner grid and said anode, and a condenser and a second resistor connected in series between said inner grid and said outer grid, said second resistor being connected adjacent said outer grid.

8.,r In a relaxation oscillator, an electron tube having cathode, inner grid, outer grid, and anode, a resistor connected between Ysaid outer grid and said cathode, a source of potential connected between said cathode and said inner grid, a second source ot potential connected between said inner grid and said anode, and a condenser and a second resistor connected in parallel between said inner grid and said outer grid.

9. In a relaxation oscillator. an electron tube having cathode, anode. and a plurality of grids, a resistor connected'between said lcathode and one of said grids. a source ot potential connected between said anode and another of said grids, a second source of potential connected between said last mentioned grid and said cathode, and a condenser and a second register connected in series between said rst mentioned grid and said last inentioncd grid.

10. In a relaxation oscillatoraan electron tube having cathode, anode, and a plurality of grids, a pair of resistors connected in series between one of said grids and said cathode. a source ot potential connected between said anode and another of said grids, a second source of potential connected between said last mentioned grid and said cathode, and a condenser connected between said last mentioned grid andthe common connection connecting said two resistors in series.

1l. In a relaxation oscillator, an electron tube having cathode, anode, and a plurality of grids, a resistor connected between said cathode and one of said grids, a source of poral.'

* tioned grid.

tential connected between said anod and another of said grids, a second source of potential connected between said. last mentioned grid and said Cathode, and a Condenser and :L second resistor connected in parallel between said first mentioned grid and said last men- ROBERT M. MGE.