US2428617A

US2428617A - Gas-filled tube type of relaxation oscillator system

Info

Publication number: US2428617A
Application number: US491440A
Authority: US
Inventors: Arthur H Dickinson
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1943-06-19
Filing date: 1943-06-19
Publication date: 1947-10-07
Anticipated expiration: 1964-10-07

Description

Oct. 7, 1947. A. H. DICKINSON ,4

GAS-FILLED TUBE TYPE OF RELAXATION OSCILLATOR SYSTEM Filed June 19, 1945 2 Sheets-Sheet 1 ans FILLED 3036 ans f/LLED I I 3 J 6e INVENTOR 'ATLI'OIRNEY Oct. 7, 1947. A. H. DICKINSON GAS-FILLED TUBE TYPE OF RELAXATION OSCILLATOR SYSTEM Filed June 19, 1943 2 Sheets-Sheet 2 I wwm www ummQ\wmvh w&m mm\ Patented Oct. 7, 1947 GAS-FILLED TUBE TYPE OF RELAXATION OSCILLATOR SYSTEM Arthur H. Dickinson, Scarsdale, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application June 19, 1943, Serial No. 491,440

8 Claims.

This application relates to electrical oscillators and is a continuation-in-part of my copending application Serial No. 314,767, filed January 20, 1940.

An object of the invention is to provide means to keep an oscillator in desired synchronism despite changes in its phase or frequency or both.

Another object is to provide means to keep an oscillator in synchronism, when operating at different frequencies and phases, in combination with a circuit network to change the frequency and phase automatically,

Another object is to provide means to keep in synchronism a group of oscillators, each having either a different frequency or phase.

Another object is to provide means whereby commonly synchronized oscillators are prevented 1 from reacting upon each other.

Other obects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, b way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 shows a circuit network embodying the invention, and

Fig. 2 is a timing chart showing waves generated by the oscillators.

The apparatus exemplifying my invention includes a primary synchronizing means which is preferably an electrical oscillator, hereafter called the main oscillator. Intermediate oscillators are synchronized by the main oscillator, these intermediate oscillators being adjusted to operate in different phase relation but at the same frequency, such frequency being a selected submultiple of the main oscillator frequency. The intermediate oscillators synchronize a plurality of other oscillators which may be called, for convenience, tertiary oscillators. The latter are synchronized for operation at the same frequency but in different phase, such frequency being a selected submultiple of the intermediate oscillator frequency and, hence, a smaller submultipl of the main oscillator frequency. A variable frequency and phase oscillator is directly synchronized by the main oscillator. A control network is provided for automatically changing frequency of this variable oscillator. The waves generated at the changed frequency have different phases than the waves which were generated at the previous frequency, The control network also functions automatically to return the variable oscillator to operation at the previous fre- 2 quency. The waves then generated will have either the same or a different phase than the waves previously produced at this frequencydepending on the duration of the intervening operation at the changed frequency. Operation of the control network is governed selectively by the tertiary oscillators. The variable oscillator frequencies are all submultiples of the main oscillator frequencies.

As illustrative, relaxation oscillators are used but it will be understood that other suitable electrical oscillators may be used.

A relaxation oscillator includes a condenser, an impedance through which it is charged, and a short circuiting device to cause its discharge.

The charging period is relatively gradual, while the discharging period is substantially instantaneous. The charge and discharge of the condenser are repeated periodically, and saw-toothed. waves are generated. In the present case it is.

varied or regulated to determine at what anode.

potential the gas tube is to fire and short circuit the condenser. In a manner explained later, the

grids of the gas tubes contained in the oscillatorsv to be synchronized receive an increment of synchronizing voltage, reducing the grid bias of these tubes. The anode voltage of these tubes is determined by the voltage across the related condensers. has reached a critical value coordinate with the reduced grid bias will ignite in response to the increment of synchronizing voltage.

Fig. 1 shows circuits which are generally similar to circuits found in my said copending application and, wherever convenient, correspondence of parts will be indicated by using the same reference characters as in the copending application.

In detail, plus and minus lines I and 2 are connected to a suitabl D. C. supply. The upper part of Fig. 1 shows, at the left, the main oscillator, which will be identified as 22m26m, and at the right, two intermediate oscillators which will be The three- Only those tubes whose anode potential identified as 22g-261g and, 22h-26h. The middle part of Fig. 1 shows two tertiary oscillators 22a26a, and 22e--26e, flanking two triodes and related elements. The bottom part of Fig. 1 shows the variable oscillator 22-26 and the control network for automatically charging its frequency or. phase or both. Since all the oscilla: tors are ofthe same nature, only one needbe described in essential detail, The others will be de scribed only in respect to features peculiar to themselves. Similar parts ofthe; differentoscib lators will be recognized by common reference numbers applied thereto.

The main oscillator will be described. indetail.

This oscillator includes condenser. ZZm-conriected'...

via resistance 27m in series with pentode 23m and in parallel with gas tube 26m. Pentode 23m has its control grid connected to line 2and-is self-biased by respectively coarsely and finely ad.-

J'ustable resistors

24m and 25m. The screen grid of. thepentode is connected to point 33m between resistors 34m and35m serving as, a volte age: divider across lines I and 2. The return circuit of'the control grid, of the gas tube is through resistance 3lm tonpoint 33m and thence Via resistor -35m, to line 2. Thus, the voltage at pointz3'3m'determinesboththe screen voltage of the'pentode and the; grid bias of; the gas'tube: A.

suitablefrequency for the oscillator-may be. see lected by changing the adjustment-of: one or more of'the following. condenser 2.2m, resistance 2am, and resistance V2 5112. When the voltage across. the condenser, reaches criticalvalue for the main tainedgrid bias of' the gas tube, this tubefires, short" circuiting the condenser:

the potent-i'al'at point 6m: Following the discharge, the condenser'begins to recharge; and

The grid ofjthe. gas tube 269 is connected by re:

sistor 3l.g to .point 395g of a voltage divider com.- prised of resistances 333g and 32g, Resistance 32g is, wired to point. 339 of the voltage divider 349,-359 of the oscillator 229-2691. Resistance 3.039 is. coupled. by condenser 302g to wire 313i. whichconnects to .point Sim ofthe. main oscillator. In the. absenceof a pulse of rising voltage on point 6m,, thev potential, at point. 3.959,. is relatively low and the gridbiasof .tube 25g .is.then.at. what may. be. called anormal value, Upon eachsharprisein voltage on ,pointfim, it. transmitsapulse via. line. 3,01 and condenser 30.2 to voltage divider. 3 3954295, momentarilyapply-in ian incrementof voltageto point 305a,. Thisincrement of.voltage. supplementsthe normal-voltage. on the: grid of. tube 26g.- to reduce the grid biasbelow normal. value. Thereupon, thetubelfigtends to ignite, but. whether: this actually takessplace depends on Wheher the anode, potential-- of. tube 26g, determined; by the potential. across the condenser 2211; has; reachedtherequisite ionizing-.- value in relation tothe; momentarily reduced grid. bias of the tube.

Similarly; point. iimtransmits synchronizing pulsesof: positive voltage via: line-301 and. acondensen Bil-2hrtel-the intermediate: oscillator 22-h*-- H1 andaviarline 3zlfland'condenser 3B2tothe variable oscillator- 2'2.='2-61-. Ina, similar manner;

Such discharge is-substantially instantaneous and sharply raises the rid of tube 25a receives synchronizing pulses 7 point 6h act through condenser 382e, to reduce the grid'bias: of. tube 256, while with the switch in the reverse position, the pulses on point to act through this condenser upon the grid of the tube 262.

Toaid; in the further description, the operations of the oscillators will be referred to a common chosen time base or cycle. This cycle is here chosen, for convenience, as the cycle of the variable oscillator 2226 during itsoperation at the lower of two frequencies. For convenience, such lower frequency may be called the base. frequency. A complete oscillation at the basefrequency requires one cycle period, as indicated in cycle I]? of Fig. 2. The variable oscillator, ina;

manner explained later, is shiftable automatically to a frequency double the base frequency; This shift, ifoccurring an odd number of index points from'thepeak of thebase oscillation causes the double frequency oscillations to be phased at mid-index points, as indicated by thepartially dotted waves at the bottom of Fig. 2; If the shift occurs at an even number of index pointsfrom the .peak of the base oscillation, the double frequency oscillations have an exact index point phaseas indicated by the .partially dotted wave inthe' next to last timing line of Fig. 2.. Thus, the base oscillations of the variable'oscillator, may have any exact point phase while the double frequency oscillations may have any exact index point 07" any mid-index point phase. In all,.with the example chosen, there are twenty possible phases of the variable oscillator, ten exact index point phases and ten mid-index point phases. The scheme of my invention accordingly provides, for the chosen example, at least twenty synchroniz= ing pulses a. cycle, each potentially capable. of synchronizing the variable oscillator in any, of its twenty possible phases and at either of its two frequencies. These synchronizing pulses are applied by the main oscillator which is adjusted for a frequency of twenty oscillations a cycle, as in: dicated inFig. 2. With the oscillator 22*26 operating atnormal frequency, there will be one effective synchronizing pulse a cycle, such pulse beingapplied at an exact index point. With the oscillator 22-2.6'operating at double the normal frequency, two synchronizing pulses will'be effective each cyclic period, such. pulses being either exact or mid-index point pulses. The other pulses, while reducing the grid bias of the tube 26,. do not cause ignition of the tube because condenser 22is not applying the necessary ionizing potential at. the times such pulses are being applied, Manifestly, difierent synchronizing pulses. become effective when'the variable oscillator changes its phase.

For reasons which will be clear later, the oscillator. 22'e.-26e is required to generate oscillations at. half. the. normal frequency of the variable oscillator; that is, to produce one oscillation every two cyclic. periods. It is desired, further, that such oscillation have any of ten possible phases, although it may be mentioned that only nine of these. phases are utilized; namely, phases at.

index points 9. to 1. Oscillator 22e-2.6.c. thus,

requires synchronization at any of the index points of a cycle. Such synchronization is effected either by intermediate oscillator 22g-26g or 22h-26h, depending on the position of switch S (Fig. 1). Each intermediate oscillator is adjusted to a frequency of five oscillations a cycle, but the oscillations of 22g2'6g are phased at even index points, 8, 6, 4, 2, and D and those of 22h--26h at odd index points9, '7, 5, 3, and 1. Thus, a synchronizing pulse is produced by one or the other intermediate distributors at each index point. When the oscillator 22e-26e is to operate at an odd index point phase, it is connected by switch S to oscillator 22h-Z6h, as indicated at the right of Fig. 2 where the arrows indicate the direction of flow of the synchronizing pulses or which of the oscillators are adapted to be synchronized by others of the oscillators. When oscillator 22e26e is to have an even index point phase, switch S is shifted to connect it to oscillator 22g2'6g for synchronization. With this arrangement, one pulse every two cyclic periods, produced either by 2'2g26g or 22h-26h is effective to synchronize the oscillator 22e26e at its selected index point phase.

As previously explained, the intermediate osci1- lators are synchronized by pulses from the main oscillator. Every fourth pulse produced at even index points by the main oscillator takes effect upon oscillator 2'2g26g to keep it synchronized, and every fourth pulse produced at odd index points is effective to synchronize the oscillator Hit-25h.

Oscillator 22a26a, for reasons explained later, is adjusted to operate at a frequency of one oscillation every two cycles and at a D phase. This oscillator is locked in such phase by a pulse produced at the D cycle point by intermediate oscillator 22g26g.

The foregoing has described, as an example, means whereby a primary synchronizing meansthe main oscillator-produces twenty synchronizing pulses a cycle, the intermediate oscillators produce five such pulses a cycle, the tertiary oscillators have a frequency of one oscillation every two cycles, and the variable oscillator has a frequency of either one or two oscillations a cycle. It will be noted that all the synchronized oscillators operate at submultiple frequencies of the main oscillator, and the tertiary oscillators also operate at a submultiple of the frequency of the intermediate oscillators. Further, the oscillations of the synchronized oscillators may have any of a plurality of different phases. By the means employed here and described above, all of the oscillators are maintained in locked or synchronized relation despite their operations at various frequencies and phases, such frequencies, however, being in all cases submultiples of the main oscillator frequency. The relations between the oscillators hold true for different submultiple frequencies, other than those illustrated in Fig. 2.

It is understood that the increment of synchronizing voltage acting on the grid of a gas tube should be insufficient by itself to cause ignition as, otherwise, there would be a tendency for the controlled oscillator to operate at the same frequency and in step with the synchronizing oscillator. The increment of synchronizing voltage should be such that when added to the normal voltage, there is a total grid potential which is effective to fire the tube only upon condition that the potential across the condenser has attained a predetermined critical value. The

resistances of the voltage divider to which the grid is connected and to which the synchronizing pulse is applied are so proportioned that only a small proportion of the pulse voltage is effective upon the grid. Considering oscillator 22g 26g, for instance, the resistance 393g has a higher value than resistance 32g, so that the proportion of the synchronizing pulse applied to the grid of tube 26g is relatively small. The condensers, such as 392g, further attenuate the synchronizing pulses.

It is well known that when the grid-controlled gas tube is ignited, there is grid current flow.- Since, in a relaxation oscillator, the time during which the gas tube is ignited is of the order of 1 microseconds, the current flow is in the nature of a steep pulse. As previously explained, the two intermediate oscillators while having the same frequency are to operate at different phases. As indicated in Fig. 2, the phase difference between these two oscillators is the cycle portion between two successive cycle points. It follows that as the gas tube of one intermediate oscillator ignites, the anode potential of the gas tube of the other intermediate oscillator is approximately one-half the desired critical anode potential. Since, in the circuits, as shown in Fig. l, the grids of the

gas tube

26g and 26h are connected to a common line 31H, there is a tendency for the pulse produced by grid current fiow in one tube when ignited to raise the potential of the grid of the other tube. Such interaction, if allowed to occur, might throw the intermediate oscillatorsout of their desired phase relation by causing undesired pre-ignition of the gas tubes at lower than the desired critical anode potentials. Further both the intermediate oscil-' lators, by reason of their grid current flow, tend to react upon the main oscillator to alter its frequency. Similarly, with switch S in position op posite the one shown, there is a tendency for the oscillators 22a-26a and 22e26e to react upon each other as well as upon oscillator 22g-26g. In the shown position of the switch, oscillator 22e-26e tends to react upon oscillator Hit-26h. Oscillator 2229 has a tendency toreact upon the main oscillator. To counteract these reactions and interactions, the grid current pulses are almost completely attenuated. Part of such attenuation is obtained by making the grid resistors 3| and My, 71,, a, and e as high in value as possible without affecting stability of the associated gas tubes. Further attenuation is obtained by making the upper resistors of the voltage dividers, to which the grid resistors are directly connected, higher in value than the lower resistors; e. g., resistor 393g is made larger in value than resistor 32g. Still further attenuation is effected by the

condensers

302, 302g, 71., a, and e.

It may be mentioned that it is preferred to synchronize the tertiary oscillators by the intermediate oscillators rather than by the main oscillator because the tertiary oscillators thereby may be more readily adjusted to their desired phase relations. This is because the intermediate oscillators together produce only one synchronizing pulse for each possible phase of the tertiary oscillators.

Since the main, intermediate, and tertiary oscillators, once adjusted to desired frequencies, are to remain at these frequencies, the screen grids of their pentodes are connected to points of fixed potentials. On the other hand, it is intended to operate the variable oscillator at a 7. base frequency or a multiple thereof; twice the base frequency in the assumed example; To enablethe variable oscillator to be varied in frequency, the screen grid of its pentode is connected to, a point which is at either of two voltages. This point is in a control network which will now be described. I

The'control network includes a voltage divider comprised of resistors 29 and 36. Resistor 30 is tapped at a, chosen point 550 by a connection to the screen of pentode 23. A point 28, of this voltage divider is connected to the cathode of a gas tube 55. The anode of this tube is connected via a resistor 43 to a point 45 of a voltage divider comprised of resistor 33, tube 39a, and selfbiasing resistor 592. The grid of tube 55 is connected via a resistance 31 to a point 48 of a third voltage divider comprised of resistor 40,

tube 42a, and self-biasing resistor 44. The resistances of the control network are so related that with tube 39a, at relatively high impedance,

tube 42a similarly at relatively high impedance,

and gas tube 55 shut off, the point 45 is near the potential of line I, point 28 is near the potential of line 2, and point 48 is still nearer the potential of line 2. Under these conditions, the voltage difference between points 45 and 28is sufiicient to supply ionization potential forv tube 55but the grid bias, which is the difference in potential between

points

28 and 48 is *sohigh as to prevent ignition of the tube. With the tube 55 in non-conductive condition, point 28 is at the lower of two possible potentials and point 5500f resistor 31] also is at the lower of two possible potentials. The screen potential of'pentode 23 is then relatively low and the tube impedance relatively high, causing the variable oscillator to function at the lower or base frequency.

Assume that the frequency of the variable oscillator is to be multiplied. Positive potential is applied, in a manner explained later, to the grid of tube 42a, reducing its bias and impedance, and, thereby, increasing the voltage at point 48. As a result, the grid bias of the gas tube 55 is lowered to such an extent as to cause ignition of the gas tube. Current now flows from point 45 to point 28, raising the potential at this point and at point 509. Consequently, the screen voltage of pentode 23 is raised and the pentodes impedance reduced, causing the variable oscillator to start operating at the higher frequency. In the assumed example, the variable oscillator values and the values of the control network are so chosen and adjusted that, upon ignition of the gas tube 55, the frequency of the variable oscillator is doubled. It is understood thatv other multiples of the base frequency may be provided for by suitable pre-adjustrnents of the circuitvalues. 7

Assume now that the variable oscillator is to be restored to operation at base frequency. In a manner described later, positive potential is applied to the grid of tube 39a, reducing its grid bias andits impedance. Current flow inresistor 38 thereupon increases to such extent as to re. duce the potential at point 45 below the value required to apply ionization potential to gas tube 55. Hence, the gas tube is extinguished and points 23 and 500 return to their original low potentials and the impedance of the pentode 23-returns to its original, high value. Accordingly, the variable oscillator again functions at the base frequency.

The firing pulse; that is, the pulse applied to the grid of the tube 42a to cause ignition of gas tube '55; is indirectly derived'from the tertiary oscillator 22a-26e. The shut-oil. pulse; that is, the pulse applied to the grid of tube39a' to extinguish gas tube 55, is indirectly derived; from the tertiary oscillator 22a-26a;

Considering first the oscillator 22a-25a, upon the breakdown of its tube a, there is an extremely rapid drop in potential across the resistor 21a, causing discharge of a condenser 95,.which produces a sharp negative pulse on resistor 95. The grid bias of tube 91a rises, reducing current flow through resistor 58 and the tube. Point 99 thereupon rises in potential, charging up a con:- denser lilil to produce a positive pulse on resistor 44. This pulse has the same steep characteristic as the pulse produced in resistor 21a upon break,-

down of the tube 26a. The positive pulse on'resistor is applied via wire 44?) to the grid of. tube 39a, causing shut-off of gas tube 55..

Similarly, upon the breakdown of tube 26a of oscillator 22e25e, condenser E! discharges, pro:- ducing a steep negative pulse, on resistor 62, which is converted by the action-of the tube 6%, resistor 54, and the condenser 66 to, a steep. positive pulse on a resistorfi'l. Assuming a switch 553 to be open, the positive pulse on resistor 61' is transmitted by wires 68 and 554 to the grid of tube 42a, causing ignition of the gas tube 55.

In the present example, it is assumed that oscillator 2Za25a is adjusted to operate at half the base frequency of the variable oscillator 2225 and that each oscillation has a D phase. Thus, at alternate D index points, the oscillator 22a25a produces a shut-oil pulse, causing the tube 55, if ignited, to be shut off at such times. It'is assumed, further, that oscillator 22e26e is to have the same frequency as oscillator 22a26 a but that its phase shall-be adjusted to any of the index points 9 to 1. cated in Fig. 2, the oscillator ZZe-Zfie has been adjusted in one instance to produce a pulse at index point 5 of every two cycles and in the other instance to produce a pulse at index point 4 of every two cycles. When the oscillator 22e.--26e is tobe adjusted to any odd index point phase, switch S is left in the position shown, in which case it will be synchronized by oscillator 22h-2 6h. When the oscillator 22e25e is tobe adjusted to an even index point phase, switch Sis shifted to reverse position, so that the oscillator 226-266. will be synchronized by oscillator 22g.-25g,

As an example, assume the variable oscillator 2225 is to be shifted from a 6 phase to a D phase (see the next to last line of Fig, 2'). The oscillatorZZe-Ziie is adjusted to the 4 phase and thereafter the switch 593 (Fig. 1) is opened. Accordingly, the pulse produced on resistance 51 at the 4 time of the first or second cycle following the opening of switch 503, will be applied via lines 68 and 554 to the grid of tube 42a, causing ignition of the tube 55. The frequency of the variable oscillator 22--26.immediately doubles as indicated at point are of the next to last line of Fig. 2. If the operation of the variable oscillator were permitted to continue at the doubled rate, its oscillations would be in successive phases D and 5 as indicated by the dotted portion in the next to last line, of Fig. 2. However, at the D time followingits shift to a doubled frequency, the variable oscillator is restored to base frequency operation. At this D time, the oscillator 22a-2fia causes a positive pulse to be produced on resistor 44, This pulse is transmitted via wire 44'!) to the grid of tube 390., as a result of which the gas tube 55 is Thus, as indi- 9. 'shut off, restoring the variable oscillator to'its base frequency. The quenching of gas tube 55, in the example under discussion, is coincident with the D phase of the double frequency oscillations, and the variable oscillator begins immediately to charge the condenser 22 at the reduced rate. The variable oscillator will then continue to operate at base frequency and its oscillations will have a D phase until the next shift is effected.

A another example, assume the variable oscillator 22-26 is operating at base frequency and at 8 phase and is to be shifted to a 3 phase. The oscillator 22e-26e is adjusted to a 5 phase, as indicated in the upper of the two lines in Fig. 2 pertaining to this oscillator. The switch 503 i then opened and the next discharge of the condenser 22c at the 5 time produces a positive pulse on resistor fill which is transmitted by

wires

68 and 5% to tube 420.. The gas tube 55 is thereupon ignited, and the variable oscillator begins to operate at the double frequency, as indicated at point 5H of the bottom line of Fig. 2. At thi doubled frequency, the oscillator 22-2E would be phased at 1.5 and 6.5, as indicated, partially in dotted lines, at the bottom of Fig. 2. At the D time following the change in its frequency, the oscillator 2226 is restored to base frequency under'control of oscillator 22a26a in the manner described before. The variable oscillator will now generate the base frequency oscillations at phase 3.

It should be understood that if the oscillator 22e26e has been adjusted to a particular phase, and switch 503 is re-closed after the phase of the variable oscillator 22-26 has been shifted once, the latter will remain in the shifted phase. Should it be desired to effect a different phase shift, the oscillator 22e26e is adjusted according to the extent of the new phase shift and switch 503 is re-opened. If the oscillator 22e-26e is adjusted to a particular phase, and switch 503 is left open for a multiple number of two-cycle intervals, successive phase shifts of the variable oscillator will be effected, one shift every two cycles, to an extent determined by the phase of the oscillator 22e26e. Thus, if this oscillator is phased at 5 and the variable oscillator is initially in an 8 phase, the latter will be shifted first from the 8 phase to the 3 phase (see the last line of Fig. 2), then from the 3 phase to the 8 phase, and so on, one such shift occurring every two cycles as long as switch 503 is left open.

As previously explained, the main oscillator supplies at least as many pulses a cycle as the possible number of phases of the variable oscillator when operating at the base frequency and the multiple frequency, In the present instance, synchronizing pulses are afforded at intervals of half a cycle division; 1. e., at mid-index points and exact index points. By supplying potentially effective synchronizing pulses at this rate to the variable oscillator, the main oscillator assures accurate phasing of the variable oscillator when it is shifted from one frequency to the other. Further, since the main oscillator also serves to synchronize the intermediate oscillators and, through them, the tertiary oscillators, it is assured that the control network will operate in predetermined relation to the phases of the variable oscillator. Hence, the extent of phase shift of the variable oscillator may be accurately controlled.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment itwill be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In combination with an electrical oscillator circuit including a variable impedance determining by its value one or another of different frequencies of the oscillator circuit, a control network including a gaseous discharge tube determining by its status one or another of alternative electrical conditions of the network, means so operatively associating the control network with said impedance as to alter its value and, thereby, the frequency of the oscillator circuit, upon a change in said electrical condition, meanssup plying a firing pulse to the control network to fire the tube therein and thereby to change the condition thereof, whereupon the frequency of the oscillator circuit is changed, means supplying an extinguishing pulse to the network to extinguish the tube therein and return the network to its previous condition, whereupon the oscillator circuit is restored to its previous frequency, means for supplying synchronizing pulses to the oscillator circuit at a rate at least equal to one of said frequencies and a multiple of the different frequency, so as to lock the oscillator circuit at any of its frequencies in desired phase relation to a given time base, and means for so timing the production of the firing and extinguishing pulses with respect to the operation of the oscillator circuit at any of its frequencies that the changes in-frequency of the oscillator circuit, resulting from changes in electrical condition of the network produced by the firing and extinguishing pulses, occur in definite, known time base relation to the operation of the oscillator circuit at any of its frequencies.

2. In combination with a relaxation oscillator operable either at a given frequency or double this frequency, said oscillator when operating at a given frequency being phased at any chosen cycle point of a given cycle and when operating at the double frequency being phased either at any chosen cycle point or at any chosen midcycle point of the cycle, means responsive to an electrical pulsation for automatically shifting the frequency and hase of the oscillator, and means producing synchronizing pulses and impressing them upon the oscillator at a frequency at least equal to th double frequency of the oscillator so as to lock the oscillator, while operating at either frequency, in any phase or phases to which the oscillator is adjusted.

3. In combination with an electrical oscillator circuit adjustable to operate at a given frequency or a multiple frequency, means including electronic discharge means responsive to an electrical pulsation for automatically adjusting a constant or constants of the circuit to effect a transition from one frequency to the other or vice Versa, means producing synchronizing pulses at a rate at least equal the multiple frequency, and means for impressing said pulses upon the circuit to assure fly-back operation of the circuit at definite phase times of a chosen cycle while operating at either frequency and upon a transition from either frequency to the other.

tio-ns to a given time base while operating at the given frequency and also while operating at the multiple frequency, whereby upon the transition in frequency of theoscillator circuit it is brought from one said locked phase relation to another I said locked phase relation. at the new frequency.

s 5. In combination, a plurality of relaxation oscillators, e'ach including a short-circuiting gas tube and a condenser applying anode-to-cathode potential to the tube, each tube including a control grid responsive to a synchronizing pulse to ignite the tube when requisite anode-to-cathode potential is being impressed upon the tube oy the condenser, each said oscillator being adjusted to operate at a different phase or frequency, a synchronizing oscillator producing synchronizing pulses, circuits commonly fed from the synchronizing oscillator for applying the synchronizing pulses to the relaxation oscillators, one circuit applying the pulses to the control grid of one relaxation oscillator and the other circuit applying the pulses to the control grid of another of the relaxation oscillators, and current choking means in said circuits to choke grid current produced in each relaxation oscillator upon ignition of the tube therein so as to prevent such grid current ,in one relaxation oscillator from effectively reacting upon the grid of another said relaxation oscillator and so as to prevent said grid current in either oscillator from effectively reacting up on the synchronizing oscillator, whereby the frequencies and phases for which the oscillators are set remain undisturbed.

6. The combination with an electrical oscillator circuit including electrical control means variable in value to establish one or another .of different frequencies of the oscillator circuit, one frequency being a multiple of the other, of a control circuit operatively connected to the variable means and adjustable in electrical condition to so afiect the value of the variable means as to produce a change in frequency of the oscillator circuit, means producing an electrical pulse and impressing the pulse upon said control circuit to adjust its electrical condition and thereby produce a change in frequency of the oscillator circuit, means impressing synchronizing pulses upon the oscillator circuit at a fixed frequency equal to at least the higher of said different frequena chosen cycle, and means so timing operation of the pulse producing means with respect to,op eration of the oscillator that the change in electrical condition of the control circuit occurs in definite time relation to the operation of. the

j oscillator.

cies, so as to synchronize operation of the oscillator circuit at each frequency with respect to 7. In combination with an electrical oscillator circuit including electrical means variable in electrical value to cause a change'in operation of the oscillator circuit fromagiven frequ'encyto a different frequency, a control circuit operatively connected to the electrical, variable means todetermine the electrical value thereof and, thereby, to determine at which frequency the oscillator circuit is operating, means for producing and impressing an electrical pulse upon said control circult to change its electrical condition and thereby, through the variable means, "to change the frequencyof the oscillator circuit, means apply ing synchronizing potential to the oscillator circuit at a frequency which is at least equal to'one of the frequencies of the oscillator circuit and a multiple of the different frequency, means for V applying synchronizingponentialto the-'pulserproducing means, and a pulsing means electrically coupled to both of the two aforementioned syns chronizing potential applying means for locking both the latter means into synchronism, whereb a change in condition of the control circuit occurs in synchronized time relation to, phases of the oscillator circuit while operating atany of its different frequencies.

- ,7 8. The combination with a'relaxation oscillator including a variable impedance electronic discharge device determining by its impedance value a base frequency of the oscillator or an alternative frequency thereof, said discharge device including control means variable in potential to vary the impedance value of the device, of a to its previous frequency-upon. a reverse change 7 in condition of the circuit, one said frequency-being a submultiple of the other said frequency, a synchronizing oscillator producing synchronizing pulses at a frequency at least equal ,tothe higher of the two frequencies of the oscillator, and means applying saidsynchronizing pulses toan input'circuit of the-oscillator so'as to synchronize it in relation to a given time basewhile operating either at the higher frequency or the submu t le fr quency. s I i ARTHUR DICKINSON. 7

REFERENCES CITED I V The following references are of record in the file of'thi's patent: 1 r

1 UNITED STATES PATENTS.

Number Name Date 2,266,516 Russell Dec. 16, 194-1- 2,1'3-2,e5.4 Oct. 11,1938 ;j2 ,22 7,e1'5 7 Jan. 7,1941 2,113,165 I Young Apr. 5, 1938 .2,-11'.'7,"58'7 'Young May 17, 1938 2,236,532

Gibb l Apr. 1, 194 1