US2375695A

US2375695A - Oscillation generator

Info

Publication number: US2375695A
Application number: US459756A
Authority: US
Inventors: Shaper Harry Bryant
Original assignee: Brush Development Co
Current assignee: Brush Development Co
Priority date: 1942-09-26
Filing date: 1942-09-26
Publication date: 1945-05-08
Anticipated expiration: 1962-05-08

Description

May 8, 1945- H. B. sHAPlRo 2,375,695

oscILLA'TIo'N GENRAToR l Filed sept. 26. 1942 2 Skeeter-sheety 1 My s,4 1945. H. B. SHAPIRO l 2,375,695

osvlcILLATIoN `GENERATOR Filed sept.2s, 1942 2 sneeisfsheet, 2

HG. AE

N V EN TOR.

HABE Y .SNAP/ea Now BY Juol CML CHANGE 0F NAME hunny B. SHAPE/z Patented May8, 1945 man "quency osoILLATIoN GENERATOR, "Harry B. Shapiro,leveland Heights, Ohio, now i by judicial cha-nge of name Harry Bryant Shaper, assigner to The Brush Development Company,A Cleve @Ohioi'` y l land, Ohio, a corporationo'f Application september ze, 194.2, serial No. 459,756 11` claims. (015250-361 c c tooscillation generators and, 'more particularly, to oscillation generators of` `the variable frequency type,

When taking curves exemplifying `the frequen'cyeresponse of various transducers Vsuch as c invention relates telephone receivers, loudspeakers `'and the like, it

is advantageous to utilize an oscillationgenerator that` provides an output current which` may be caused to vary over a wide range ofaudio fre- Y types such,`for example, as the audio beat frequenoy type wherein the output, `at `audio Vfre-` lis obtained throughthe interaction ofthe currents from two relatively high freoutput q'e'ifc'y oscillators, one iixedfand one variable. 55

The generator, furthermoramay `be of the type that is mechanically tunableover a specific range or thetuning thereof may be"-e1ec`tronically controlled, the only `requirement `.being thatit shall clude a frequency-determining element -theeffective impedance oflwhich may be caused to varyby the aforementioned reactance tube. i'

For example, when practicing the invention in connection with a beat frequency oscillation genquencies and which., if ldesired, may be caused to erator, the reactance tube may be supplied with` wobble or Warble a" predeterminedpercentage ,c warble-control` potentials from a variable low above and below any frequency within said range. c frequency oscillator 'and a biasing potential for Previous to `this invention,` `the warble has the tube,` derived from'the generator itself, may-be been obtained through utilization of `a mechanin utilized to `cause the gain vtherein to `v'alryjafs*a callyvdriven tuning device, suchas an'auxiliary l5 function of the frequency fof the youtput, frcm the shunt capacitor of the type shown in the patent to generator. Alternatively, the reactance jtube may Farrington No.` 2,205,190. t With suchfa device, the be provided with a xed'biasand be Supplied "with l warble frequency is not a constant percentage control potentials from the warble oscillator, the of the Iparticular base frequency being warbled amplitude'of the saidpoten'tials being `causez'ito `but always has a fixed band Widthunless auxiliary 2o vary as a function of 'the frequency of the outcompensating means are employed. c i put from the generator'. VIn a still furtherem- Itis, accordingly, an object of thisk invention to bodiment, a varying` biasing Vpotential y may 'be provide an` oscillation generatonthe `output from derived `from the variable high frequency oscil- Which maybe warbled a, predetermined per; c lator comprised in the generator'instead offrom centage of any frequency within its range. t the output of the generatoritself andsuch poten- Another object is to providea warble oscillatial maybe applied to the reactancejtube directly tor wherein the percentage of frequency swing'` is or it"may` be utilized to control "the amplitudejof adjustable at the will of the operator. i the potentials supplied thereto from thell'ow Anotheriobject is toprovide a warbleoscillaf t ,i frequency oscillator. c Y j tor wherein the percentage offrequency swing, 3U `The novel features considered characteristic after having once been adjusted, remains substanof the `invention areset `forth withparticularityn tially constant over the output range. the appended claims. `Theflnvention itself, `howl,Another object is to provide `a warble, oscilever, bothfas to its organization andfitsmethod lator the base frequencies 'of which are substan 0f Operation, together with further "Ubll'sjn'd tially independent of the Warble-control devices. advantages "thereof, 'Will best be understood from A still further object is to providean oscillator the following .description j0`f ,Certain "SD'GIG of the type described thai-,shall not require meembodiments, when read in connection with the c hanically moving parts for obtaining the warble accompanying .drawingSQin Whihf c effect. i f c t `Figure lis" acircuit diagramexemplifying `an In accordance with the invention, electronic 40 embOdlment of heinvention; c ,c warble-controlmeans are substituted fortheusual Figure 2 is a circuit diagram exempllfyin'g jan mechanically actuated warble` capacitor, such alternative'embodime'nt; Bildf 1 r i means, preferably, `including a reaetanee tube Figure 3 is acircuitdia'gramlexemplifying anthat `may be `so energized and connected as to cyother `embodiment of theinvention. c clically cause a minor change inthe effective in- In all figures of the drawings, identicaleleinent's ductance, capacity or resistance of a frequencyc are Similarly designated. i c determining network in an oscillation generator, Referring to Figure v,1 ofthe drawings, 1anlmautomatically under control of a current or pobodiment of the invention mayinclude aivariable tenuar `denveafnm said generator. The osbeat-frequency generator, indicated eenerally'bv cillation generator may be of any of the usual the Ilumelial D10Vding`a`n Output Current at audio, supersonic or radio frequency,whichgen` 5 eratorincludesla frequencyi-deterniining network,V or a tank circuitsuch asc might beconstituted fby an'inductor Sshuntedbya capacitor l. L'I'h'eteln frequency determining network Aisntenrlleu"to f include a, xed or variable tuned circuit, a variable or fixed capacitor, inductor or resistor, or any other circuit element or network that plays a part in determining th'e frequency of the oscillations generated and/or delivered to an output circuit.

For the purpose of varying the effective reactl ance of the inductor 3, it may be connected across the output circuit of a thermionic tube 1 of the variable mu pentode type, such as the 956, and connections are provided whereby the tube draws a current that lags the alternating potential appearing across the inductor. l

To obtain proper grid excitation for the tube, at the frequency of the potential appearing across the inductor 3, the connections include a phase shifting network, constituted by a resistor 9 in l l R c the current in the said capacitor will be substantially in phase with the potential across the tank circuit, with the result that the alternating potential appearing across the capacitor I l, which is applied to the control grid I3 of the reactancev tube, lags the potential impressed across the network from the inductor and the tube I I, therefore, draws a lagging current and functions as an inductor .connected in shunt to the inductor 3.

Preferably, the high potential supply circuit for the reactance tube includes an inductor I9 that offers highreactance at the frequency de'- termined by the inductor 3 and the capacitor 5.

For the purpose of introducing warble into the system, the extent of which, or swing, increases `with increasing frequency ofthe output current from the generator, the control grid I3 of the reactance tube 1 is connected to the cathode thereof by Way of a grid leak 2l, a resistor 23 constituting the output circuit of a rectifier and a tapped resistor 21 included in the output circuit of a low-frequency warble control oscillator 29.

'The rectifier 25 is supplied with input currents from the output circuit of the generator, the supply circuit including a low-pass filter such as a series resistor 3I and a shunt connected capacitor 33. The positive terminal of the rectifier output resistor 23 is conductively connected to the cathode of the reactance tube and the negative terminal thereof to the grid of the tube, whereby the biasing potential supplied to the grid I3 becomes less negative as the frequency of the output current fromltheg'enerator increases. The gain in the reactance tube, accordingly, increases With rising output frequency and the reactance-change, at'the warble oscillator rate, that it can cause, is thus automatically made greater at the high frequency end of the range than at the low frequency end.

Through proper choice of the values of the various circuit elements illustrated, such as the

resistors

23 and 21, the percentage of frequencyshift, or warble, may be controlled, and after once having been set it remains constant over the entire output range.

applied to the warble' control tube 4I by the recti-A Should the connection of the reactance tube to the inductor 3 disturb the calibration of the oscillation generator, one or more padding capacitors 3,5 may be employed for Icompensation.

'A modification of the invention is illustrated by Figure 2. In that embodiment, the reactance tube 1 is connected to the frequency determining element 3 comprised in a variable oscillation generator in substantially the same manner as described with reference to Figure 1. A rectifier 25 is also provided which gives an output current that decreases in response to increase in frequency of the output current from the generator. The reactance tube 1, however, is given a fixed bias from a resistor 31 in the cathode circuit thereof and the control grid I3 therein is connected to the cathode by way of the resistor 2| anda potentiometer 39 included in the output circuit of a warble control tube 4I, which may be of the variable muA type such as a 6SK7. Grid bias for the Warble control tubedl is supplied by a circuit which includes the output resistor 23 of the rectifier 25 and a variable portion of the warble oscillator output resistor 21. Accordingly, the amplitude of the signal introduced from the warble control tube into the grid circuit of the reactance tube 1 is a function of the setting of the potentiometer 39,of the bias, varying with frequency, supplied from the resistor 23 and of the amount of the warble-oscillator output resistor 21 that is included in the circuit. The bias fier 25 may be permanently adjusted to select the most favorable part of the mutual conductancegrid bias curve, if desired. f i

Instead of utilizing the output current from the beat frequency generator to provide a Warbleamplitude, or swing-control, essentially the same result-,may be obtained by making useof a portion of the output current from the variable high frequency oscillator. That is to say, referring to Figure 3, a portion of the output from the tunable high frequency oscillator portion 45 of the generator may be fed to an auxiliaryamplilier 41 the output from which is supplied to the rectifier' 25 that provides a unidirectional current which varies in accordance with the frequency of the said oscillator. The rectifier outputrnay be utilized for varying the effectiveness of a reactance tube associated with a frequency determining element or network in the fixed oscillator 49, as described in connection with Figure 1 or y Figure 2.

Inasmuch as many alternative modes 'of warble` control, by utilizing the varying current provided by the rectifier, will be obvious to those skilled in the art without departing from `the spirit of the invention, they havev been merely indicated in Figure 3 by a rectangle 5I, with the general designation warble-control devices. 7

' An'oscillation generator constructed in accordance with the invention has numerous advantages among which may be mentioned the following as perhaps being the most important:

' (al The integral of energy, in each band examined by means of the warble, is constant.,`

(b) The band width at each point in the range, when warble is introduced, is automatically so adjusted that no over-shooting of zero frequency takes place at the low frequency end of the range. (c) The rate of warble is easily changed, which enables the avoidance of warble frequencies that might coincide with resonance frequenciesof the meters or other indicating apparatus utilized.

(d) The percentage of warble is easily'changed,

` characterized in this: that the Other advantages, as well as` alternative embodiments of the invention, will be apparent to those skilled in the art. The invention, therefore, is not to be restricted by the specific embodiments chosen for illustrative purposes, nor

rents to vary cyclically, and means responsive to the frequency of the generated currents for causing the percentage of cyclic variation to be constant over the frequency-range of the oscillator.

2. An loscillation generator having an output circuit `and having a given frequency` range, adjustable reactor means connected to said oscilla- `tion generator for influencing the output frequency of said oscillation generator within said frequency range, means interconnecting said output circuit with said reactor means and including means for establishing a rst potential in accordance with currents delivered to the output circuit of said oscillation generator, oscillator means for establishing a second potential which varies cyclically, said first and said second potentials being added to establish asummation potential for adjusting the reactance of said reactor means for influencing the output frequency of said oscillation generator within its frequency range in accordance with a constant percentage function of thefrequency of the currents delivered to the` said output circuit and in accordance with thev cyclically varying output from said oscillator.

3. The invention as set forth in claim 2 further frequency of said oscillation generator is mechanically changeable Within its said frequencyrange, whereby said summation potential is altered to influence the frequency of the output signal from said oscillation generator.

4. The invention as set forth in claim 2 further characterized in this: that the said means for establishing a first potential is a means for establishing adirect current in accordance with the currents delivered to the said output circuit of said oscillation generator.

5. The invention as set forth in claim A2 further characterized in this: .that the said adjustable reactor means includes a reactor tube having a grid and a cathode and whose grid voltage determines its reactance, said summation potential being applied to said reactance tube between the said grid and cathode.

6. The invention as set forth in claim 2 further characterized in this: that the said adjustable reactor means is a reactance tube having agrid and a cathode and whose grid voltage determines its reactance, and that said means for establishing the said first potential is means for establishing av direct current potential.

7. The invention as set forth in claim 2 further 10; characterized in this: that the said oscillationl generator is a beat frequency generator.

8. In combination, an oscillation generator having'a given frequency range, reactor means connected to said` oscillation generator for iniiuencing the frequency of the generated oscillations, means connected to the said oscillation generator for causing the frequency of the generated currents to vary `cyclically, and means responsive to the frequency of the generated currents for causing the percentage of frequency variation to be constant over the frequency-range of the said oscillator.

9.` The invention as set forth in claim 8 further characterized in this: that the said reactor means includes a reactor tube whose grid voltage determines its reactance, and that the means responsive to the frequency of the generated currents for causing the percentage of variation to be constant over the frequency-range of the said oscillator is a means for varying said grid voltage.

10. The invention as set forth in claim 8 further characterized in this: that said oscillation generator is a beat-frequency generator and its `frequency is mechanically changeable over substantially its entire frequency range, and that` the said reactor means includes a reactor tube whose grid voltage determines its reactance, and

. that the means responsive to the frequency of l the generated currents for causing the percentage of `variation to be constant over the frequencyrange of the said oscillator is a means forvarying said grid voltage.

11. An oscillation generator including a, frequency-determining reactor and having a generator output circuit; a thermionic tube having an input circuit, and having an output circuit connected effectively in parallel to said reactor; means for impressing on said input circuit a lagging potential derived from said reactor;

.means for impressing oscillations at low frequency upon said input circuit; and means responsive to the frequency of the currents delivered to said generator output circuit for determining the amplitude of said impressed low frequency oscillations.

i HARRY B. sHAPIRo, Now` by Judicial` Change of Name Harry B. Shaper.