US2402169A - Double pulse oscillator - Google Patents

Description

Lm 1s, 1946. H. LIFSCHUTZ "2,402,169

DOUBLE PULSE OSCILLATOR Hard Lifffscvutz June 18, 1946. H. LlFscHu-rz DOUBLE-PULSE OSCILLATOR Filed March 27, 1942 2 Sheets-Sheet 2 wmdw im ...lo vm m L* d l 0 W H Fatenie June I18, 1946l DOUBLE PULSE O SCILLATOR u Harold Llfschutz, Washington, D. C., now by' judicial change of name Harold Lyons Application March 27, 1942, serial No. 436,469 1s claims. (ci. 315-26) (Granted under the act o! March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to oscillator circuits and more particularly to circuits for generating double pulses.

There has been a need in the art for a circuit capable of generating a double pulse output, since such output may beemployed in numerous instances for controlling operation of or calibrating various electrical machines. For example, the output of a double pulse generator may be utilized to measure the resolving time of an electronic counter circuit. or may be employed to operate electronic switches of the scale-of-two type in which case the time that the switch is opened or closed is dependent upon the time interval of separation of the double pulses.l Y

It is therefore an object of the present invention to provide an oscillator circuit for generating double pulses.

Another object is to provide a double pulse generator which includes means for varying the time interval or the separation between the double pulses.

Another object is to provide a double pulse generator with means for maintaining the time interval between the double pulses constant, and

including means to vary the rate of repetition of double pulses.

Another object is to provide a double pulse generatpr which includes a pair of non-oscillating vacuum tubes each driven by a source of sawtooth voltage whereby each of the tubes produce a pulse upon application of each cycle of a sawtooth voltage thereto, with means varying the time that each of said tubes produce a pulse.

Stili another object of the invention is to provide a double pulse generator interconnected with an oscillograph in such a manner to indicate the double pulses whereby the time interval or separation therebetween may be accurately measured.

Still another object is to provide a double pulse generator interconnected with an oscillosraph for indicating the output of the generator, with means synchronizing the output of the generator with the operation of the oscillograph with a erence for the latter purpose being had to the appended claims. l

` In the drawings, wherein, similar referencia characters denote similar parts throughout the several views:

Fig. 1 is a block diagram of a double pulse generator interconnected with an oscillograph;

Fig. 2 is a circuit diagram of the generator disclosed in Fig. l; i

Fig. 3 is a schematic showing of the voltage applied 'to grid 36 of tube shown in Fig. 2;

Fig.. 4 is a schematic showing ofthe voltages of grid 3l of tube 39 shown in Fig. 2, and a Fig. 5 is a diagrammatic showing of the double pulse output oi the oscillator disclosed in Fig's. 1 and 2.

With reference more particularly to Fig. 1 -of` the drawings a-double pulsegenerator is'disclosed therein including a saw-toothwave generator IIJ which simultaneously feeds saw-toothwave forms, through buier ampliers Il and I2 to pulser circuits I3 and I4. The saw-tooth wave input to pulser circuits I3 and I4 controls operation of the latter circuits in such a manner that a negative and a positive pulse is generated at the output of ea'ch of the circuits upon application of each cyclev of the saw-tooth voltage Y thereto.- The pulsating outputs of pulser circuits timing wave for calibrating the double pulse patl tern on the oscillosraph.

signed for purposes of illustration only and not as a deilnition oi the limits of the invention, ref- `output of the generator.

I3 and I l are fed through rectifying buffer ampliilers I5 and I6 to output'terminals I1 and I8 of the generator. As will appear more fully hereinaiter, means are provided in pulser circuits I3 and Il for varying the time between generation of pulses at each of the circuits, upon simultaneous application of saw-tooth wave cycles thereto, to thus vary the time interval or the separation between the double pulse output at terminals I1 and I8. Buier amplifiers II and, I2 function to segregate pulser circuits I3 and I4 from 4the saw-tooth Wave generator IIl and from each other so that the outputs of the pulser circuits are completely independent of the time interval or separation between the double. pulses, while rectifylng buiier ampliiiers I5 and I6 function to rectify and amplify the pulsating output of puiser circuits I3 and I4 to produce extremely sharp pulses of a predetermined polarity at the,

In practically all instances of application of the double pulse generator described above, it is A necessary to know the time interval or the separation between the double pulses. Means are therefore provided by the present invention for indicating the output of vthe double pulse generator and for properly calibrating such indication ascenso Y. 3 I so that the time interval between double pulses may be accurately measured. As shown in Fig. l. the output of the double pulse generator is fed to vertical de'ection plates I9 and of csail-'- lograph. 2 l, while the sweep voltage-for the Oscil- .lograph is .derived directly from the output of sawtooth wave generator i0, and such voltase is applied to horizontal deflection plates 23 and 24 of the oscillograph. This `arrangement obtains automatic equality of the oscillograph sweep and the double pulse frequencies as well as maintain# ing extreme steadiness of the oscillograph pattern.V In order to calibrate the osciiiograph pattern so that the time interval between double pulses 'produced thereon may be readily measured, a calibrated timing wave is impressed on the vertical deflection plates of the oscillograph. As shown, a timing wave generator io. such as .a calibrated beat frequency oscillator, is provided which supplies al timing wave to the vertical de- :dection plates of the .osciilograph to superimpose a timing wave on the oscillograph pattern. In order to maintain the timing wave pattern on the oscillograph stationary with respect to the double pulse pattern, the timing wave output of generator 80 controls operation of the saw-tooth wave generator i0 to thus completely synchronize the entire system.

The circuit diagram' of the double pulse generator isdisclosed in Fig. 2. Asshown, saw, tooth wave generator l0 comprises a relaxation oscillator which includes a thermionic gas-filled tube '25 having the plate and cathode thereof re spectively connectedY to positive and groundpotential in a conventional manner. Capacitances 21, 28 and 29, of different capacities, may be individually connected in the plate-cathode circuit of tube 215 in .order to vary the frequency of gen erator i0. Capacitances 30 and 3l are connected to the plate1` of -tube 25, between resistentes 32 and 33, for coupling the output of saw-tooth wave generator i0 to tubes 34 and 35. When positive potentials applied through resistances l2 and 33, capacitance 29, or capacitance 21 or 2l. receives an increasing charge. the value of which is determined by the value of the potential applied to the plate of tube 25, and by the value of the capacitance. As the charge of either capacitance 21. 28 or 29 builds up. the plate of tube 25 receives a corresponding potential. When the .potential on the plate of tub'e 25 reaches a sumcient value to render the tube conducting, the potential charge'of capacitance 21. 28 or 29 is discharged through tube 25 to complete generation of the saw-tooth wave form.

and, as thecharge decreases the Potential of the plate of tube 25 likewise decreases. As the plate potential decreases to the cut-oi! potentiel-0f tube 25. the charge on capacitances 21. 2l ori!! again increases to generating the next saw-tooth wave form. When timing wave generator Il is utilized, the potential of the grid of tube 25, which is normally biased negative through resistance 28, is varied in accordance with the output ol generator 80 to control the time of discharge of tube 25.

The saw-tooth voltage output of generator Il is fed to buifer ampliners I I and I2 each of which respectively include duplex triode vacuum tubes 34 and- I5 thus providing a two-stage amplifier. The saw-tooth wave forms are thus amplified and applied tov control grids Il and $1 of pulser tubes 38 and J9 respectively.' Tubes 38 and .$5 are thermionic gas-filled tubes and are connected in puiser circuits I3 and il in such a mannerlto cut-off potentials are established at each of the tubes. and the tubes are therefore rendered conducting when a potential is applied to the' grids thereof that corresponds to the above mentioned cut-oil' potentials. By applying the necessary negative direct-current potential to grids Il and 31 to cause the saw-tooth voltages from amplifiers ii and i2, to swing across the cut-oil' potentials of each of the tubes. the tubes will be blocked and rendered conducting upon application of each cycle of the saw-tooth voltage. This may be more readily understood with reference to Fig. 3, wherein the input voltages to grid Il are -diagrammatically shown; As disclosed, the cuto potential of tube I! is established by the positive potential applied to the plate thereof', while the negative direct-current bias on grid Il is saw-tooth voltage to swing across the line representing `the cut-oil potential. When the s awtooth wave sweeps, thus driving grid It more negative, the saw-tooth waveform will cross the line of cut-off potential at point a thus quenching tube It. As the saw-tooth wavecontinues to sweep, the tube will remain non-conducting until the saw-tooth waveagain crosses the line of cut-ci! potential at point b. Tube 88 then remains in a conductingstate for the completion of the cycle of the sawtooth wave and until the subsequent saw-tooth wavecycie passes the line oi' cut-on potential at Va' to thus again quench the tube. It is to be expressly understood, therefore, that for application of each cycle of the saw-tooth voltage. tube Il is quenched and then rendered conducting, and therefore the tube generates a positive and a negative pulse upon application of each cycle of the saw-tooth voltage. Since it is desired to obtain output pulses of minimum width. the pulses generated during the time that the tube 38 is rendered conducting are utilized. since it has been found that the quenching period of the tube is substantially greater than the striking time thereof.

As mentioned heretofore. one of the objects of the present. invention is to provide a double pulse generator including means for Avai-.ving the time interval or the separation between the double pulse. Such means comprises'potenticmeters 'I2 and ll which are adapted to control the negative direct current bias on grids' 3l and I1 in such a manner that. upon simultaneous* application .of a cycle of saw-tooth voltage thereto the tubes will be quenched and rendered conducting at diiferent instances during movement of the saw-tooth wave cycle to thus generate negative pulses at different instances. As shown in Fig. 3, since the saw-tooth voltages vary with respect to the line. of cutoif potential upon variation of the negative saw-tooth voltages applied to grid 31 are thus caused to cross the line of cut-off potential at higher points on the saw-tooth waves than the line of cut-oil potential is crossed by the sawtooth waves shown in Fig. 3. Therefore, the tubes are quenched at approximately the same time since the wave-form of each saw-tooth cycle is substantially vertical when the current is moving more negative, and tube 38 is rendered conducting prior to tube 39 since the line of cut-off potential of tube 38 is crossed by the saw-tooth wave during the period when the latter is becoming less negative, before a similar action occurs at tube 38. The foregoing means thus prov vides a very accurate method of varying the time interval or the separation between the double pulse output of the generator.

Buier amplifiers Il and I2 not only Provide suitable amplification and the proper number of phase shifts of the saw-tooth voltage output of generator I0, but, as stated heretofore, completely isolate tubes 38 and 39 from generator I0 and from each other to prevent interaction between the tubes. When potentiometers 42 and 43 are adjusted in such a manner that the separation between the pulse outputs of the tubes is extremely small, a few microseconds for example, the grid current drawn by one tube upon generation of a pulse would immediatelyl drive the other tube conducting, thus reducing the time interval to uro in the event buffer amplifiers II and I2 were not provided.

As stated heretofore, when tubes 38 and 38 are rendered conducting, a negative pulse is generated at the outputs thereof'and such pulses are utilized for the output pulses of the generator.

When the tubes are rendered conducting negative pulses are generated instantaneously, followed by a substantially slower rise to normal potential and therefore it becomes necessary, In order to obtain sharp pulses, to amplify the high frequency components of these pulsesand provide means for rejecting the low frequency components thereof. Such means are included in rectifying buffer amplifiers I5 and I8 each of which comprise a two-stage amplifier having a high transductance tube in each stage. Amplifier I5 comprising tubes 44 and 45, while tubes 45 and 41 are included in amplifier I8. In order to obtain high frequency response of each of the tubes of the ampliiiers suitableinductances are included in the plate circuits of each of the tubes. As shownl inductances 48 and 43 are respectively included in plate circuits of tubes 44 and 45 while inductances 50 and 5I are included in similar circuits associated with tubes 48 and 41. By utilizing high transconductance tubes in each stageof amplifiers I5 and I8 the necessary gain is obtained to provide sharp pulses without` substantially increasing the pulse width. By suitably selecting the values of inductances 43, 49, 50 and 8|, and the values of resistances 52 associated with each of the inductances, a large range of pulse widths and amplitudes, within certain-.-limits', may be obtained. Amplifiers I5 and I8 are biased insueh 6 a manner to'only amplify the negative pulses generated by tubes 38 and 39, and protentiometers 53 and 54 are included therein for controlling the amplitude of the pulses. A negative double pulse output is thus obtained at terminals I1 and I8, as disclosed in Fig. 5 of the drawings. The separation of time interval T between the pulses may be readily varied by operation of potentiometers 42. and 43 in a manner Vnoted heretofore.

When the circuit shown in Fig. 2 is utilized in connection with oscillograph 2l in a manner disclosed in Fig. l, the output of timing wave generator. is fed to output terminal I'I by way of connection controlled by switch 55, thus synconducting, grid current is drawn by these tubes which in turn distorts the saw-tooth wave form of the relaxation oscillator.. Buffer amplifying tubes 34 and 35,.positionei|between the relaxation oscillator and the puiser tubes, prevent such distortion of the output wave form of the relaxa-l tion oscillator and consequently prevent a simultaneous distortion of the pulse pattern of the oscillograph.

There is thus provided by the present invention a novel oscillator circuit for generating double pulses which includes/means for maintaining a predetermined time interval or separation between the pulses Moreover, means are provided for varying such time interval so that an extremely small separation, of'a few microseconds, is maintained between the pulses. or for varying such time interval so that a substantially greater separation is obtained. The circuit is of such construction that extremely sharp pulses of substantially narrow width are provided at the output thereof and so that 'the pulses may be supplied to a suitable indicator, such as an oscillograph, whereon a pattern of the pulses may be obtained' simultaneously with a synchronizing wave whereby the separation may be accurately measured. Y l

The invention described herein may be manufactured and used by or for the Government of the United States of-America for governmental ,purposes without the payment of any royalties thereon or thereforfy Whatis claimed is: l 1. A circuit for generating double pulses comprisins a pair of electron discharge devices each having a plate, a cathode and a control electrode. meansapplying ,equal positivepotentials to said plates wherebyequal cut-offpotentiais are .established at each .of said devices, meanssimuitaneously applying saw-'tooth voltages to each of said control electrodes, and means applying direct current potentials to each of said control electrodes to cause the saw-tooth voltages to swing across said cut-oil.' potentials wherebyeach of said devices is rendered conducting vand quenched upon application rif-.each cycle ofssaid saw-tooth voltages. i'

v2. A circuit for generating doublefpuises .cor- 'prisinga pair of electron discharge devices each. j

havinga platea cathode and a, control electrode' means applying equal positive potentials to said plates whereby equal cut-oil.'V potentials are established at each of said devices, means simultaneously applying saw-tooth voltages to each of said control electrodes and means applying direct current potentials to each of said control electrodes to cause the saw-tooth voltages to swing across said cut-ofi potentials whereby each of said devices is rendered conducting and 'selfquenched upon application of each cycle of said saw-tooth voltages, the direct current potential to one of said electrodes being less than the direct current potential to the other electrode i'or rendering one of said devices conducting before the other device.

3. A circuit for generating double pulses comprising a pair of electron discharge devices each having a plate, a cathode and a control electrode, means applying equal positive potentials to said plates whereby equal cut-oil' potentials are established at each of said devices, means simultaneously applying saw-tooth voltages to each of said control electrodes, means applying direct current potentials to each of said control electrodes to cause the saw-tooth voltages to swing across said cut-oil potentials whereby each of said devices is rendered conducting and selfquenched upon application of each cycle of said saw-tooth voltages, and means producing a variation in the direct current potential to said control electrodes for rendering one of said devices conducting before the other device.

4. A double pulse generator comprising a pair of electron discharge devices each having a plate, a cathode and at least one control electrode, means applying equal positive potential to each of said plates for establishing equal cutfoil potentials at each of said devices, means simultaneously applying saw-tooth voltages to each of said control electrodes, means applying direct current potential to each of said control electrodes for causing the saw-tooth voltages to swing across said cut-oi! potentials whereby each of said devices is cut-oi! `and rendered conducting and quenched upon application of each cycle oi' said saw-tooth voltages, and means varying the direct current potential applied to said control electrodes for varying `the time that the said devices are rendered conducting.

5. A double pulse generator comprising a pair of electron discharge devices each having a plate, a cathode and a control electrode, means applying equal positive potential to said plates for establishing equal cut-oi! potentials at each of said devices, means simultaneously applying saw-tooth voltages to each of. said control electrodes in the same phase relation, means applying negative potential to each of said control electrodes for causing said saw-toot`h voltages to swing across said cut-oi! potentials whereby each of said devices is rendered conducting and quenched upon application of each cycle of said saw-tooth voltages, and means .varying the negative potentials applied to said. control electrodes with respect to each other for causing the saw-tooth voltages to cross said cut-oi! potentials at dinerent points where by the devices are rendered' conducting at different instances.

6. A double pulse generator comprising a oscillator for generating saw-tooth wave forms, a pair of non-oscillatingl electron discharge devices each having a plate, a cathode and a control electrode,

ously applying said saw-tooth wave forms to the control electrodes for 'controlling said devices, and means applying negative bias to said control electrodes for causing said saw-tooth wave forms to swing across said cut-o potentials whereby each of said devices are quenched and then rendered conducting upon application of every cycle of said saw-tooth wave forms.

7. A double pulse generator comprising a oscillator for generating saw-tooth wave forms, a pair of non-oscillating electron discharge devices each having a plate, a cathode and a control electrode, means applying equal positive potentials to each of said plates for establishing equal cutoff potentials at each of said devices, means simultaneously applying said saw-tooth wave forms to the control electrodes for controlling said devices, meansl applying negative bias to said control electrodes for causing said saw-tooth'wave forms to swing across said cut-off potentials whereby each oi said devices are quenched and then rendered conducting upon application of' every cycle of said saw-tooth wave forms, and means varying the negative bias applied to said control electrode for causing the devices to be rendered conducting at different times.

8. A double pulse generator comprising a relaxation oscillator forgenerating saw-tooth wave forms, a pair of non-oscillating electron discharge devices each having a plate, a cathode and a control electrode, means applying equal positive potentials to each of said plates for establishing equal cut-ofi potentials at each of said devices. means simultaneously applying said saw-tooth wave forms to the control electrodes for controlling said devices, means isolating each of said devices from the other, means applying negative bias to said control electrodes for causing said saw-tooth wave forms to swing across said cutoif potentials whereby each of saiddevices are quenched and then rendered conducting upon application of every cycle of said saw-tooth wave forms, and means varying the negative bias applied to said controlelectrode for causing the devices to be 'rendered conducting at diilerent times. A

9. A double pulse generator comprising a relaxation oscillator for generating saw-tooth wave forms, a pair of non-oscillating electron discharge devices each having a plate, a cathode and a control electrode, means applying equal positive potentials to each of said plates for establishing equal cut-off potentials at each o! said devices, means simultaneously applying'said saw-tooth wave forms to the control electrodes for controlling said devices, means applying negative bias to said controlelectrodes for causing said saw-tooth wave forms to swing across said cut-oi! potentials whereby each o! said devices are quenched and then rendered conducting upon application of every cycle of said sawtooth wave forms, means varying the negative bias applied to said control electrode for causing the devices to be rendered conducting at different times, and a pair of buner ampliiier means positioned between said oscillator and each 'of said devices for preventingY interaction between the devices.

10. A double pulse generator comprising a relaxation oscillator for generating saw-tooth wave forms, a pair of electron dischargef'devices each having a plate, a cathode and a control electrode, means applying equal positive potential to each of said plates for establishing equal cut-oil potentials at each of said devices, means simulphase, means applying negative bias to each of said control electrodes for causing' said saw-tooth wave forms to swing across said cut-off potentials whereby each of said devices is quenched and rendered conducting upon application of every cycle of said saw-tooth wave forms to generate a positive and a negative impulse at the output of each of said devices, means varying the negative bias to each of said control electrodes for causing the devices to be rendered conducting at diilerent instants, and means rectifying the output of each of said devices to obtain impulses of a predetermined polarity.

11. A double pulse generator comprising a relaxation oscillator for generating saw-tooth wave forms, a pair of electron discharge devices each having a plate, a cathode and a control electrode, means applying equal positive potential to each of said plates for establishing equal cut-oil potentials at each of said devices, means simultaneously applying said saw-tooth wave forms to each of said control electrodes in the same phase. means positioned between said oscillator and each of said devices for preventing interaction between the devices, means applying negative bias to each of said control electrodes for causing said sawtooth wave forms to swing across said cut-off potentials whereby each of said devices is quenched and rendered conducting upon application of every cycle of said saw-tooth wave forms to generate a positive and a negative impulse at the output of each of said devices, means varying the negative bias to each of said control electrodes for causing the devices to be rendered conducting at dill'erent instants, and means rectii'ying the output of each of said devices to obtain impulses of a predetermined polarity.

12. In an apparatus of the class described. an oscillograph, a saw-tooth wave generator, means driven by-said generator for producing double pulses upon application of a unidirectional portion of said saw-tooth wave thereto, means applying the double pulses to a pair of deilection plates of said oscillograph, and means applying the output of said generator to another pair of deflection plates of said oscillograph.

13. In an apparatus of the class, described an oscillograph, a relaxation oscillator for generate' ing saw-tooth waves, a timing wave generator for controlling said oscillator, means driven by said saw-tooth waves for generating double pulses upon application of a unidirectional portion o f said saw-tooth waves thereto. means applying said double pulses to a pair of deiiection plates of said oscillograph, means applying the output o! said oscillator to another pair of deflection plates of said oscillograph, and means passing the output o! said-generator to said one pair of deection plates.

14. In an apparatus of the class described, an oscillograph, a saw-tooth wave generator, means driven by said generator for producing double pulses upon application of every cycle of said sawtooth waves thereto, means varying the time interval between said double pulses, means applying the double pulses to a pair of deection plates of said oscillograph for producing said double 10 pulses on the screen of said oscillograph where by said time interval may be readily determined.

15. An apparatus of the class described comprising an oscillograph, a relaxation oscillator 5 for generating saw-tooth voltage, a timing wave generator controlling said oscillator, means driven by said oscillator for generatingI double pulses upon application of every cycle of said saw-tooth voltage thereto, means establishing a time interval between said double pulses, means applying said double pulses to one pair of deflection plates of said oscillograph, means applying the output.

of said oscillator to another fpair of deflection plates of said oscillograph for producing a pat-- tern of the double pulses on the screen of the.

for generating saw toothrvoltages, a timing wavegenerator controlling said oscillator, means driven upon application of every cycle of said saw tooth voltage thereto, means establishing a time interval between said double pulses, means varying said time interval, means applying said double so pulses to one pair of deilectionplates of said oscillograph, means applying'the output of said oscillator to another pair of deflection plates oifsald oscillograph for producing a double pulse pattern on the screen of the oscillograph, and means applying the output of said generator to said one -pair of deflection plates for synchronizing the doublepulse pattern onrthe screen of said oscillograph with said timing wave whereby said time interval may vbe accurately measured.

prising a pair of electron 'discharge devices each having a plate, a cathode and a control electrode, means applying denite positive poten-` tials to said plates whereby deilnite cut-oil' potentials are established at each of said devices, means simultaneously' applying saw-tooth voltages to each of said Vcontrol electrodes to cause the saw-- tooth voltages to swing across said cut-o1 potentials whereby each of said devices is rendered oonnesting and quenched upon application of each cycle of said saw-tooth voltages.

18. A circuit for generating double pulses comprising a pair of electron discharge devices each having a plate electrode. a cathode and a con-'- trol electrode, means applying positive potentials to said plates, means applying direct current negative bias potentials to said control electrodes to render the said devices self-quenching, means .simultaneously applying a saw-tooth voltage to A e0 both said control electrodes whereby each o! said devices is rendered conducting and quenched f upon application of each cycle offsaid saw-tooth voltage, and means varying 'one of the 4said potentials as applied to one of said devicesto vary the amount of change in control-.electrode potential by said saw-tooth voltage necessary to render the said one device conducting.

by said oscillator for generating double pulses 17. A circuit for generating'double pulses com-

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