US2453203A - Variable frequency relaxation oscillator - Google Patents

Description

Nov. v97,- 1948;

Filed'June 19, 1945 FIG. 1,

A. H. DICKINSON VARIABLE FREQUENCY RELAXATION OSCILLATOR 2 Sheets-Sheet 1 INVENTOR A'TTORNEY Nov. 9, 1948. A. H. DlcKlNsoN VARIABLE FREQUENCY RELAXATION OSCILLATOR 2 `Sheets-Sheet 2 man.

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Filed June 19, 1943 Patented Nov. 9, 1948 VARIABLE FREQUENCY RELAXATION OSCILLATOR Arthur H. Dickinson, Scarsdale, N. Y., assigner to International Business Machines Corporation, New York, N. Y., a corporation of New York Application June 19, 1943, Serial No. 491,439

10 Claims.

This case relates to electrical oscillators and is a continuation-impart of my application Serial No. 314,767, led January 20, 1940.

The general object of the invention resides in the provision of a novel method and means of automatically changing the frequency and/or phase of an electrical oscillator.

An object of the invention is, further, to provide novel means for abruptly changing the frequency of an electrical oscillator and abruptly restoring the oscillator to its original frequency.

An object of the invention is, still further, to provide means for changing the phase of the oscillations produced by an electrical oscillator by temporarily changing the frequency of the oscillations.

Another object of the invention is to provide a novel electronic circuit for automatically determining the value or values of elements of an oscillator circuit so as to govern the frequency of oscillations produced by the oscillator circuit.

Another object of the invention is to provide a novel method and means for changing a, given frequency of an electrical oscillator to a submultiple of the given frequency.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by 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 is a circuit diagram of the main form of the invention, showing an arrangement for multiplying a chosen oscillator frequency.

Fig. 2 is a circuit diagram of a modication, showing an arrangement for changing the chosen frequency to a submultiple thereof.

Fig. 3 is a ldiagrammatic showing of Waves produced by the circuit of Fig.A 1 when the chosen frequency is doubled for a temporary interval having a predetermined relation to the chosen cycle.

Fig. 4 shows the timing, in relation to the chosen cycles, of the electrical control effects pertinent to the Waves shown in Fig. 3.

Fig. 5 is a diagrammatic showing of wave forms produced by the circuit of Fig. 1 when the chosen frequency is tripled for predetermined intervals.

Fig. 6 is a. timing diagram of the electrical effects pertaining to the Waves shown in Fig. 5.

Fig. 7 is a diagrammatic showing of waves produced by the circuit of Fig. 2 when the chosen frequency is temporarily halved, and

Fig. 8 is a timing diagram of the electrical effects pertaining to the waves shown in Fig. 7.

Theinvention is disclosed in connection with an oscillator of the type known as `a relaxation oscillator. According to my invention, the circuit value of an element or elements of the oscillator is varied to produce achange in frequency. The means for varying the circuit value comprises a control network including a gas-filled tube and vacuum tubes. The voltage distribution about the network differs according to whether the gasiilled tube is or is not conducting current. Thus, the value of an element or elements of the oscillator will be determined by the voltage distribution of the network which distribution is determined, in turn, by the status of the gas-filled tube. A change in the status of the gas-lled tube will automatically produce a change in frequency of the oscillator. The status of the gas-filled tube is controlled by the changes in impedance of the vacuum tubes of the control network. Voltage applied to a firing control portion of the network, such portion including a vacuum tube, will cause ignition of the gas-filled tube, while voltage applied to a shut-off control portion of the network, such portion also including a vacuum tube, will cause the gas-filled tube to be extinguished.

A relaxation oscillator is that type in which a condenser is charged, through an impedance, and discharged periodically, the discharge occurring upon short circuiting of the condenser. During the charging vportion of a cycle, there is a constant increase in voltage difference between the condenser terminals. The short circuiting o-f the condenser causes its substantially instantaneous discharge. Thus, such oscillator produces a sawtoothed wave. In the present case, a gas triode is used as the short circuiting device and a multigrid tube; specifically, a pentode, is used as the impedance in the condenser charging circuit. The pentode is used because its characteristics are such that for widely varying anode potentials, the current ilo-w therethrough remains substantially constant for a given grid bias setting. Therefore, at whatever frequency the oscillator is operating, the rise in voltage across the con- -denser will be substantially linear. The gas triode is used as a short circuiting device because its grid bias may be conveniently regulated to determine at what voltage across the condenser the triode is to break down and short circuit the condenser.

According to my invention, the frequency ofthe oscillator will be automatically changed upon a change of voltage distribution about thecon-trol network external to the oscillator. Such change will be eiected at a chosen point of a cycle. A given frequency of the oscillator is chosen conveniently as determining the base cycle. This given or chosen frequency also may be referred to as the base frequency. The frequency will be changed at a denite point of the base cyclev and at least some of the waves produced at the changed. frequency will have a different phase with respect to the base cycle than the oscillations produced at the base frequency. The return of the oscillator to the base frequency will be effected also at a denite point of a base cycle. The oscillations thereafter produced at the base frequency Will have either the same or a different phase than the base frequency oscillations which were being generated prior to the intervening change in frequency. The new phase of the-basev frequency oscillations will depend on the base cycle time elapsing between shift of the oscillator to the changedfrequency and its return to the base frequency.

In the form of invention shown in Fig. 1, means are provided to automatically cause the oscillator to change from the base frequency to a multiple ,A

of this frequency. Fig. 1 is substantially similar, except for certain additions which will be described, to one of the circuits shown in my aforementioned copending application. For convenience, parts of Fig. 1 will be given the same reference characters as corresponding parts of the copending application.

Considering Fig. 1 in detail, plus and minus lines I and 2 receive D. C. voltage from a suitable source. The relaxation oscillator comprises condenser 22, gas triode 26, and pentode 23. `A resistor 2l connects the anode of the gas tube to line I while its cathode is connected to the anode of the pentode 23. The cathode of the pentode is connected Via variable resistances 2.4 and to line 21. IThus, gas triode 26 and pentode 23' are in series across the lines I and 2. Condenser 22 is connected at one side to line l and at the opposite side to a point 6 intermediate the connection between the cathodev and anode of the gas tube and the pentode. With the stated arrangement, the condenser 22 is in parallel with the gas tube 28 and resistor 2? and is also in series with the pentode 23. The control grid of gas tube 26 is connected via protective resistance SI to a point 33, of a voltage divider comprised of resistors `34 and 35. The voltage supplied the control grid to the gas tube is accordingly determined by the potential at point 33.

Pentode 23 has its screen grid connected via a switch 58|, in the shown position, to a desired point of a voltage divider comprised of resistors 29 and 30. The potential of the screen gridis thus determined by the potential at the point of this voltage divider tapped by the connection to the screen grid, provided the switch 50i is in the position shown.

As shown, the screen grid is connected to a point of resistor 30 but it may be adjusted to point 28 or any other suitable point of the voltage divider 29-30. The control grid of the pentode may be connected, as shown, to a selected .point of resistor 30.

The resistors 24 and 25 constitute a self-biasing resistance for the pentode. One of these resistors is preferably adapted to afford a coarse adjustment of the self-bias and the other a ne adjustmentf Voltage divider 29--30 is part of the control network which experiences a change involtage distribution to automatically cause the oscillator frequency to depart from the base frequency. With the connections made as shown, the control network will a-ct through both the screen and control grids of the pentode to change the frequency of the oscillator. The control grid mal7 be connected Vdirectly to line 2, so that its potential Will beviixed. The control network then will control the frequency through the screen grid alone. On the other hand, it may be desired to have the control network change the frequency byV automatically varying the potential only of the control grid of the pentode, while the screen grid potentialremained Xed. For this purpose, 'switch-'50| may bey thrown to a position opposite the shown position, connecting the screen grid to point 33 of Voltage divider 34-35. The potential at point 33w-ill then determine not only the potentialofthe control grid of gas triode 26 but also the potential of the screen grid of pentode 23.

The control network includes, besides the mentioned voltage divider 29-30, two additional voltage dividers and a gas-filled triode 55. One of these additional voltage dividers comprises resistor 38 and vacuum tube 39a. This voltage divider serves as an extinguishing control for gas triode 55', in a manner which will be explained. The other of the voltage dividers comprisesY a resistor 40, vacuum tube 42a, and resistor 4 I. The latter voltage divider serves, in a manner to be explained, as a ring control for gas triode 55. The gas triode 55 has its anode connected, via current limiting resistance 43, to a point 45 of voltage divider 38-3 9a and its cathode connected to point 28 of voltage divider 29-30. The grid of triode 55 is connected via a 4protective resistance 3'I to a point 48 of the voltage divider 40-42a-4 I.

With tube 39a'. at relatively high impedance, point 45 is near the potential of line I. The resistors 29. and 30Y are so related in value that point 28 isy relatively near the potential of line 2. The pointsv 45. and 28 arev connected to the anode and cathode, respectively, of triode 55. With points 45 and 28 at the mentioned potentials, the dinerence in potential between them approaches that between lines I and 2 and is sunicient to supply the. desiredionization potential for tube 55.

The resistor 4I is aself-biasing resistance for tube, 42a and normally keeps the tube at relatively high impedance. Point 48 is then nearer than point 28' to the potential of line 2. Under this conditiornthe. grid bias of the gas triode 55 is so high as to prevent its ignition even though ionization. potential is being'applied to the gas triode.

Assuming the. gastriode is extinguished and it is now desiredto frreit, a positive potential is applied from a suitable source to aresistor 41. As a result, the grid bias of tube 42a is lowered and the impedance of the tube decreased, causing increased current ow throughresistance 4U, the tuba, andiresistance IH.A Point Mlthereupon rises in potential to such extent as to lower the grid bias of the gas triode 55 to the iiring value. The

gas triode thereby is ignited and remains in this `stateauntil ionizationpotential is removed.

tube 55 has been extinguished, potential-may be removed from resistor 44. Likewise, potential may be removed from resistor `Il as soon as the eas tube has been fired.

The voltage distribution about the control network; that is, the potential at various points of the, network, is determined by the status of the gas tube 55. With the gas tube in conductive status, current flows from point 45 to point 28. The value of this current flow depends upon the relative values of the impedances of the voltage dividers between which the gas tube is interposed and also upon the setting of variable resistor 43. With the gas tube serving as a conductive bridge between points 45 and 28, there is increased current ow in resistor 38, resistance 43, and resistor 3U. Such increased current in these resistors causes the potential at point 45 to drop, and the potential at point 28 and at points along resistor 30 to rise. It is understood, however,` that the constants of the circuit are such that the difference in potential between points 45 and 28 will still be great enough to supply the necessary ionization potential for the tube 55. In the foregoing manner, the tube 55 when in a conductive state maintains points along voltage divider 29-30 at relatively high potential. Vhen the tube 55 is extinguished, the original voltage distribution about the control network is restored; that is, point 45 rises in potential, and points along voltage divider 29-30 drop to relatively low potential.

Ignition and extinction of the arc in the gas tube 55 occur with extreme rapidity, so that the changes in potential at points of the control net- Work occur substantially instantaneously. The potential at points of the voltage divider 29-30 governs the frequency of the oscillator. Assuming that both the control and screen grids of the pentode 23 are connected, as shown, to points of resistor 30, the rise in potential of these points (occurring upon ignition of gas tube 55) increases the potential on these grids. The control grid bias and screen grid voltage are thus concurrently reduced and raised, respectively, and act together in reducing the impedance of the pentode. There is a rise in current through the pentode, increasing the potential at point 36; i. e., increasing the cathode potential. The control grid, however, will be connected to a point of resistor which eX- periences a greater rise in potential than the rise in potential of the cathode of the pentode. Hence, the net effect will vbe a reduced control grid bias for the pentode.

In the foregoing manner, the ignition of tube 55 raises the potential at points of resistor 3U which, in turn, causes the screen and control grids of the pentode 23 to rise in potential, causing a reduction in impedance of the pentode. When the tube 55 is extinguished, reversal of the stated effects occurs and the impedance of the pentode returns to its original value.

It may be desired to utilize only the screen grid of pentode 23 to vary the impedance of the pentode. In such case, the control grid connection will be brought directly to line 2. The changes in potential along resistor 30 will then act through the screen grid alone to vary the impedance of pentode 23. On the other hand, it may be desired to utilize only the control grid of the pentode to vary its impedance. The screen grid will then be connected by switch 5B1, in a position opposite the one shown, to point 33. The changes in potential along voltage divider 29-30 will then act through the control grid alone to change the im pedance of the pentode.

A drop in impedance of the pentode 23 lincreases the frequency of the oscillator, and a rise in impedance of the pentode reduces the frequency. Thus, upon ignition of the gas tube 55, the potential of points along the voltage divider 29-36 rises, causing the impedance of the pentode to fall, as a result of which the oscillator frequency is increased. Upon the gas tube being shut 0H, the reverse operations take place and the oscillator again functions at the base frequency.

The base frequency of the oscillator may be variably chosen by changing the setting of any one or more of the following: condenser 22, resistor 24, resistor 25, the tap point of the control grid to resistor 3U, and the tap point of the screen grid to resistor'B. It may be mentioned that further selection may be made by changing resistances 29 and 30'. When switch 50i is in position opposite the one shown, the screen grid is connected to point 33 and will be excluded from consideration in regard to variable selection of the base frequency. Likewise, if the control grid be connected to line 2, it will be excluded as a factor of adjustment of the base frequency.

The several adjustments mentioned above not only determine the base frequency but also the ratio of the increased frequency to the base frequency. In addition, this ratio depends on the setting of resistor 43 and the relative values of voltage dividers 38-39a and 29-3U. These various adjustments provide for a considerable range of base frequency and multiple frequency which may be chosen.

Fig. 3 is a diagrammatic showing of waves produced on the assumption that the circuits are adjusted to double the base frequency upon ignition of gas tube 55. The base cycle, as previously stated, is taken as the cycle of an oscillation generated at base frequency. This base cycle, referred to hereafter simply as the cycle, is divided, for convenience, into ten parts and the dividing points arenumbered l0, 9 l. Thevvaves may be taken to represent the changing voltage at a point, such as 6, of the oscillator. When the condenser 22 discharges, the voltage at point 6 rises abruptly. The voltage of point 6 then drops linearly while the condenser is being recharged. 'I'he phase of the wave will be measured by the point of the -cycle at which the wave peak occurs. Fig. 4 is a companion to Fig. 3 and indicates the voltage condition at point 28 of voltage divider 29-30. It will be noted that the wave in cycle b has a 2 phase. Assuming that the base frequency is to be doubled at point 6 of cycle c, the gas triode '55 is ignited at this point. The voltage at point 28 rises abruptly as shown at 503 of Fig. 4. Correspondingly, the frequency begins to double as indicated at 554 of Fig. 3. It will be noted that an irregular wave form is produced between point "2 of cycle b and point 4 of cycle c. The shape of the irregular wave form depends upon the phase of the wave prior to the occurrence of a change in frequency and on the point -of the cycle at which the change is effected. It will be noted, also, that the phase of the oscillations has been shifted upon doubling of the frequency. Thus, the waves produced at the doubled frequency have successive phases of 4 and 9. It is assumed that the oscillator is to be returned to base frequency at the beginning of the cycle e; i. e., at point "10 of this cycle. The gas tube 55 there- .fore is extinguished at this cycle point. The drop in potential of point 28 is indicated at 505 of Fig. Il.' The return` of the oscillations to the base fre,- quency is indicated at 506 of Fig. 3. It will be *I noted that the oscillations now again produced at the base frequency have an 8 phase. Thus, the

phase of thefoscillations produced at base frequency may be shifted in accordance with the point of the cycle at which 'the doubling of the requency occurred and thefpoint of the cycle at which the return to base frequency was effected. With the operations timed as in Fig. 3, the phase of base frequency oscillations has been shifted from 2 to 8.

Fig. 5 illustrates waves produced on the assumption that the circuits are adjusted to triple the base frequency upon ignition of the gas triode 5'5. Fig. 6 is companion to Fig. 5. Prior to ignition of the rgas triode, the oscillations are assumed to have a 4 phase. The gas tube 55 is ignited, fOr example, at point-9 of cycle c. The rise in potential of point 28 is indicated at 501 of Fig. 6 and the accompanying change of frequency is indicatedv at 508 of Fig. 5. The waves now being produced at triple the base 'frequency have successive phases of 7l/3, 4, and 102/3. It is assumed that the oscillator is to return to base frequency at of cycle d; i. e., at the beginning of this cycle. Gas tube 55 is extinguished at this point of the cycle, and the potential at terminal 28 drops as indicated at `509 of Fig. 6. The return to base frequency is indicated at 5||J of Fig. 5. As a result of the tripling of the frequency at 9 of cycle c and the return of the frequency to base value at the beginning of cycle d, the base frequency oscillations which had a phase of 4 prior to the temporary increase of frequency, have been shifted to a 2 phase, as indicated at 5| of Fig. 5.

Assume, now, that the frequency is tripled again at the beginning of cycle e. The rise in potential at terminal 28 is indicated at 5|2 of Fig. 6 and the increase in frequency at 5|3 of Fig. 5. Assume, further, that the frequency is to be restored to base value at the beginning of the next cycle f. The drop in voltage of terminal 23 is indi-cated at 5M of Fig..6 and the return to base frequency at 5|5 of Fig. 5. It will be noted that the base frequency oscillations will now have the same phase, 2, as they had prior to the tripling of the frequency for a complete cycle. Thus, a shift of the base frequency oscillations will not occur if the change in frequency endures for one or more complete cycles. This principle applies regardless of the factor of multiplication of the base frequency.

It will be evident from the examples given that the circuits may be adjusted for other multiples of the base frequency; that is, the base frequency may be quadrupled or increased ve times, and

so on.

It may be desired to reduce the base frequency automatically upon changes in voltage distribution about the control network. Fig. 2 shows a circuit arrangement whereby the ignition of the gas tube in the control network causes a reduction of vthe base frequency, Elements of Fig. 2 which are similar to elements of Fig. 1 will be given the same reference numbers followed by letter A.

Considering Fig. 2 in detail, the control network comprises three impedance branches :or voltage dividers across the plus and minus lines IA and 2A. Application of a pulse to resistance 41A increases current flow in voltage divider 40A- 42A-MA. Gas tube 55A thereupon fires. As a result, current flow through resistance 30A in- 'creases and the potential at point 28A and Aof pointsalong resistance3UA rises. To extinguish thegas tube A, a vpulse is applied to resistory v8 |||A-,causingr increased current now in voltage divided 38A-39A- This results in the quenching of the gas tube 55A.

The oscillator per se of Fig. 2 is similar to the one of Fig. l andcomprises condenser 22A, gaseous discharge tube 25A, and. pentode 23A'. In Fig. 2, however, the screen grid lof the pentode is shown as connected directly to point 33A of voltage divider 35A-35A. The screen vol-tage is thus fixed, andthe impedance -of the pen-tode will vary with the control` grid bias. The control grid ofthe pentode 23A is connected to a chosen point 5|'9 -of resistor 35A, so that the control grid potential will not be varied by the control network. Re-

sistors 24A 4and 25A are of the same nature asresistors 24 and 25 of Fig. l. Resistor 25A, however, is connected by la wire 52|] toga chosen point 52| of resistor 30A. Accordingly, the resistors 24A and 25A together with that portion of resistor 30A between pointV 52| and line 2A lprovide a selfbiasing potenti-al for pentode 23A. The difference in potential between point 36A and point 5H)` is the net icontrol grid bias for the pentode 23A.

With the arrangement shown in Fig. 2, when the gas ltube is in a conductive state, the potential at point 52| rises and increases the net self-bias of pentode 23A. Impedance of the pent-ode is increased as a result, andthe frequency of the wosf cillator reduced. The ratio of the new frequency to the base frequency depends upon the constants of ythe impedance network and upon the setting of point 52|. The base frequency may beselected by adjusting the setting of one or more of the following: points 5|9 and 52E, resistances 24A1and 25A, and condenser 22A. Y

In the foregoing manner, the circuits of Fig. 2 cause the frequency-to be decreased upon firing of the gas tube 55A, the reverse of the effect produced by :the firing of `the gas tube 55 of Fig. 1. The extinction -of the gas `tube 55A restores the oscillator to the base frequency.

Fig. 7 shows a change in the oscillations produced upon the assumption that the circuits of Fig. 2 have been adjusted to cause the base frequency to be halved upon ignition -of -thegas tube y 55A. The base oscillations are shown as initially having an 8 phase. As anexample, `the gas tube 55A is red at point 4 of cycle c. The resulting rise lin potential of point 52| (Fig. 2) is indicated at. 522 of Fig. 8, and the :accompanying change in frequency is indicated at 523 -of Fig. '7. The oscillator now functions at half :the baserate. Assuming the `oscillator is to be restored to base frequency at the lbeginning of cycle d, gas :tube 55A is extinguished at this point. The drop in potential of pcint`52| (Fig. 2) is indicated at 524 (-Fig. 8) and :the yaccompanying return to base frequency is indicated at 525 of Fig. 5. It' will be noted that the base oscillations will now have' a 6 phase. Thus, by halving the base frequency f-or four cycle points, the base oscillations have been shifted from phase 8 to phase 6.

It will be evident that the circuits of Fig. 2 may be adjusted for causing the base frequency to be reducedV to other fractions than one half, upon ignition of .the gas tube 55A. I

It will also be understood that .the oscillator may bev maintained at a changed frequency, either a multiple or a fraction of the base frequency, for

v an indefinite period.

v While there have been shown and described and pointed out the fundamental novel features of the invention as applied lto several modifications, it will be understood that various omissions and substitutions and changes in the form and' dewww tails yof the devices illustrated and in their opera'- tion may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to belimtied only as indicated by the scope of the following claims.

What is claimed is:

1. In combination, an electrical oscillator circuit including an automatically variable impedance element adjustable in impedance value to determine one -or another frequency of the oscillator circuit, and a control circuit including signal responsive means responsive to an electrical signal for automatically adjusting the impedance value of said variable impedance element so as to produce a change in frequency of the oscillator circuit, said contr-ol circuit further including electronic discharge means for sustaining the impedance constantly at the adjusted value after the signal has disappeared, and said control circuit being responsive to a later signal to restore the operation of the oscillator circuit, and a .control Y, network including means responsive to one elec- -trical signal for :automatically adjusting the impedance value of said variable impedance means to cause la change in operation of the oscillator circuit and including mean-s responsive to av following, like -electrical signal for automatically restoring the variable impedance means to its Previous impedance value so as to cause the oscillator cir-cuit to rever-t to its previous operation to operate in a phase differing from its original phase according to the interval between the signals.

3. In combination, an electrical oscillator circuit adjusted to produce waves at `a base frequency in any of different pos-sible phases within a chosen time base, a control network :automatically adjusting the constants of the oscillator circuit and having self-sustained alternative conditions in one of which it maintains the circuit so adjusted as .to operate at the base frequency .and in another of which it so alters the constants of the circuit as to cause it to depart from the base frequency, and signal responsive means operating in response to one electrical signal to alter the network from one of its conditions to the lother and operating in response to a later electrical signal to restore the network to its previous condition, so as to produce a temporary departure of the oscillator circuit from base frequency in order to effect an automatic phase shift thereof.

4. In combination, a gas-tube type of relaxation oscillator circuit adjusted to produce waves at a base frequency in any of different possible phases within a chosen .time base, a control network automatically controlling the constants of the oscillator circuit and having alternative sustained, relatively reverse conditions in one of which it maintains the -oscillator circuit so 'adjusted as to produce the waves at the base frequency :and in the other condition of which it so zalters the constants of the oscillator circuit as to depart from the base frequency, and electrical signal pulse-operated means for adjusting the network first to one said condition in response to one pulse and then to the alternative, reverse condition in response to a following pulse, whereby the network is enabled to automatically cause the oscillator circuit to depart from the base frequency and return thereto upon successive reverse changes in condition of the network in response to successive electrical signal pulses, so that upon return to its. base frequency the oscillator is in a phase differing from its previous phase according to the interval between the signals.

5. In combination, an electrical relaxation oscillator circuit adjusted to operate at `a given frequency in any of different possible phases with respect .to a given time base, a control network comprising a gas tube with a control grid, a firing control in the network responsive to an applied electrical signal for firing the gas tube to obtain one electrical condition Iof the network, an extinguishing control in the network responsive to a subsequent, applied electrical signal for extinguishing Ithe gas tube to obtain an alternative electrical condition of the network, and means electrically coupling the network to the -oscillator circuit so as automatically to adjust it differently in accordance with the different conditions of the network thereby to produce a phase shift in the oscillator circuit determined in extent by the interval relative to the time base, between the firing and extinguishing signals. i

6. In combination, an electrical oscillator circuit including an electrical element variable in electrical value and normally at such value `as to cause the oscillator to operate at a given frequency in any of different possible phases with respect to a chosen time base 4said element being adjustable in value to vcause the oscillator yto change its frequency and produce a phase shift, a trigger circuit having alternative sustained electrical conditions and electrically connected to said element of the oscillator circuit for varying its electrical value in accordance with said electrical conditions,and signal responsive means responsive to one electrical signal for producing one of said sustained electrical conditions of the trigger circuit and responsive to a following electrical signal for returning the trigger circuit to its alternative sustained condition, whereby the sustained electrical conditions of the trigger circuit are alternated in response to successive electrical signals so as to automatically act upon .the oscillator circuit to shift its phase,

7. In combination, an oscillator circuit of the relaxation type adjusted to produce waves at -a given frequency yand phased selectively with respect to a chosen time base, a control circuit changeable in electrical condition in response to one electrical signal pulse and returnable to previous electrical condition in response to a subsequent electrical signal pulse, and means so operatively connecting the control circuit to the oscillator circuit as Ito automatically transmit the effect of `the change and return in condition of the control circuit to the oscillator circuit, thereby to cause a temporary readjustment of the oscillator circuit and correspondingly temporary change in its frequency, so as to shift the oscillator circuit phase in accordance with the time, relative -to the time base, elapsing between the successive electrical signal pulses.

8. In combination, an electrical oscillator circuit adjusted to operate at a given frequency in any of different possible phases with respect to a chosen time base and including a variable impedance electronic discharge device determining the frequency of :the oscillator circuit, a trigger circuit having alternative sustained electrical conditions and triggered in response to one electrical 11 signal to one sustained condition and in response to a subsequent electrical signal triggered back -to a previous sustained electrical condition, and means electrically operatively connecting .the trigger circuit to :the variable impedance electronic discharge device so as to Vary its impedance in accordance with said electrical conditions for a time corresponding to the interval between said signals thereby to cause the oscillator circuit =to depart for such time from the given frequency and yoperate in a diierent phase after return to the given frequency.

9. In combination, an electrical oscillator 'ci1'- cuit adjusted 'to operate at a given 'frequency in any Iof different possible phases with respect to a chosen time base, a control circuit including a trigger tube for determining the electrical condition of the circuit, means so electrically coupling the con-trol circuit to the -oscillator circuit so as to adjust the latter in vaccordance with the electrical condition of the former, `and means in ythe control circuit responsive to one electrical signal'f-or triggering the tube in one direction and responsive vto a subsequent signal for triggering the tube in the reverse direction thereby to cause successive reverse changes in electrical lcondition of the control circuit, such changes being effective Ito produce corresponding lsuccessive reverse adjustments of the osillator circuit, whereby ythe phase of the oscillator circuit is shifted in accordance with the time, relative to said time base, el-apsing between the successive ltriggering operations of the trigger tube.

10. An oscillator comprising a gaseous discharge device having an anode, a cathode and ya grid, a source of anode to cathode power, `2|, condenser 12 shunted directly between saidy anode and cathode, Aan electron emission device including at least an anode,-a cathode andone grid, means conductively connectin'gsaid device in series with said ygaseous disch-arge 'device andsaid power source, and a potentiometer, in shunt with said gaseous discharge device and said electron emission device in series, a second 'gaseous discharge device connected' in shunt witna portion of said'potentiometerand means for igniting and quenching said second discharge device yto thereby produce a variation'inthe voltage at a predetermined point of said potentiometer, andmeans connecting said predeterminedpoint Iand said one grid of theelectron 'emission :device whereby the frequency of said 'oscillator maybe altered -to :adjust the phase of said oscillator to 'ad-esired phase condition.

' ARTHUR H.. DICKINSON.

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

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