Патент USA US2409621код для вставки
Patented I@cla 22, 1946 2,409,620 UNITED STATES PATENT »oi-‘FICE OSCILLATION GENERATOR Walter W. Fritschi, Manhasset, N. Y., assignor to Bell Telephone Laboratories, Incorporated,` New York, N. Y., a corporation of New York Application January 17, 1942, Serial No. 427,131 7 Claims. (Cl. Z50-«36) 2 This invention relates tol oscillators and par ticularly to vacuum tube oscillation generators of the feedback type. The invention has for its object the provision . is obtained when the oscillator is designed to sat isfactorily regulate the amplitude ofthe voltage of the signaling frequency; and , of a simple, single vacuum tube oscillator adapted Fig. 3 shows the envelope shape when insuiii-` cient voltage regulation is provided. >The oscillator shown in Fig. 1 of the drawing D to supply signaling current of a desired frequency interrupted at a desired rate, and the production of sufficient output power `'in 'such an oscillator with the amplitude ratios desired and with sat isfactory limits of voltage and frequency varia tion under variable load conditions. comprises a vacuum tube Ill, a feedback resistor I9, a variable condenser 2l), an induction coil vacuum tube oscillator designed to simultaneously comprising windings 2l and 22, a potentiometer comprising resistor 23 and brush 24, an induction coil comprising windings 3|, 32 and 33, impedance element 35, condensers 35 and 3l', a potentiometer comprising resistor 38 and brush 39„ an output transformer Ml, and output terminals 4I and 42. The tube I0 is of the screen grid high amplifica tion type having a thermionic cathode I5, control grid Id, screen grid I3, anode II, and a pair of produce oscillations at the signaling frequency electron beam conñning plates I2, positioned be This invention is an oscillator comprising a single vacuum tube arranged to produce oscilla tions of a desired signaling frequency and to interrupt the signaling frequency at a desired rate. A feature of the invention is a single and‘at the rate of interruption desired, the- ratio tween the anode I I and screen grid I3. Reference between the amplitudes of the twoy frequencies 20 may be had to the> patent to Ol. H. Shade No. >being adjusted so that the feedback of the lower 2,107,520, granted February 8,`1938„for a detailed frequencyv alternately drives’ theV grid potential description of a‘tube lof the preferred structure into a range wherein the amplification is insuiñ cient to sustain oscillation at the higher frequency and character. The ‘cathode I5 is indirectly heated by a heating element I6 in usual manner, and the beam deflecting plates l2 are electrically connected to the‘cathode. While the tube’shown is o‘f the beam type, a high amplification tube without beam deiiecting plates maybe used. >The anodef‘cathode space current circuit is traced from anode I! through winding 2l of oneinduc tion coil, through winding 3| and a partof wind ing 32 of the other `induction coil, brush‘ 30, and through battery 50 to the cathode I5. The con denser 36 is bridged across the windings 3l, 32 and `33 to form a tuned network which is resonantL to the desired signaling frequency, fory instance and into a range wherein oscillation .at the higher frequency is sustained.A Oscillation at the lower frequency is sustained by the inertia'of its tuned circuit and the higher, signaling frequency is thereby effectively interrupted at the rate of the lower frequency of oscillation. 30 Other features of the invention are the pro vision of volume limiting means in such an oscil lator and the provision of a shunt, having a nega tive impedance-voltage coefficient, across the net~ > work which is tuned to the signaling frequency to obtain a more constant amplitudeoi ‘the sig naling frequency. ‘ 35 l000"cycle's'per`second; and the variable conf` _ A clear and complete understanding of the denser 2D‘is bridged across the winding 2I to form altuned network which is resonant at the fre quency at which.À it Yis desired that the signaling invention will be facilitated‘by a.' description of ‘ the oscillator illustrated schematically inA the drawing, in which oscillator the invention fand frequency’be interrupted, for instance 15 cyclesV per second. Condenser 2B is variable torpermit adjustment of its capacity to tune the condenser and ‘Winding 2l -to the desired interrupting fre its various features are embodied. The invention is not limited to the specific arrangement shown, various modifications being possible within the scope of the invention. 45 quency. „ The ` Referring to the drawing which consistsof three figures, ` ' n Fig. 1 shows an oscillationgenerator compris ing a single vacuum ‘tube lI0 arranged to generate oscillations of La desiredsignaling frequency and to generate oscillations of a desired interrupting frequency at which the oscillations of the signal ing‘frequency are interrupted;' p , _A „ , ‘ Fig. 2 shows an oscillogram V'of the output of control `grid-cathode circuit is traced from grid I4 through resistor I9,- tolpoten tiorneter brush 24, through> resistor 23 in parallel with winding 22„thence to potentiometer'brush Y. 50 39, through resistor`38 to cathode I5. The control grid" is not biased byía direct current` source <and ~ bothfthe signaling frequency andthe interrupting frequency are fed back tol the controlgrid; thel. `amount of feedback being dependent `upon the adjustment of‘lbrushes 2li and `3i). The resistor the oscillator shown in Fig. 1; thi's'envelope shape 55 I9- has a high resistance to'limit the grid circuit. '2,409,620 3 4 The primary winding of output transformer 40 is bridged across the winding 3l and an impedance and the grid potential again builds up to and be yond the cut-off point, the signaling frequency element 35 having a negative temperature-voltage coefficient, is bridged across the winding 33 and reappears. Thus in either case, that is with zero grid bias or with a negative grid bias, the sig a part of the winding 32 as determined by the Oi naling frequency voltage is stopped and started at the interrupting frequency and substantially position of brush 34 to limit the amplitude of the complete suppression of the signaling frequency oscillations of the signaling frequency. The ele is obtained during one half-cycle of the voltage of ment 35~may consist of silicon carbide of such the interrupting frequency. dimension and character as to provide the desired The oscillograms shown in Figs. 2 and 3 indi range of impedance. By adjustment of brush 35 cate that the envelope shape of the signaling fre the portion of induction coil winding 32 which quency may be regulated by the character of the is included in the anode-cathode circuit may be negative-impedance element 35, a satisfactory varied and by adjustment of brush 34 the amount envelope being illustrated in Fig. 2 and an un of inductance which is shunted by element 35 satisfactory envelope resulting from insufficient may be varied. The condenser 3l, which is in regulation on the part of element 35 being illus series with potentiometer resistor 38, is effective trated in Fig. 3. These two oscillograms illustrate to prevent direct current through the resistor. the range of envelope shapes which it is possible Assume that the feedback potentiometers have to obtain through control of the amplitudes of the been adjusted to obtain the desired feedback po tentials and that the oscillator is placed in op 20 two frequencies of oscillation by the element 35 and the amount of attenuation in the feedback eration, for instance, by the closing of the bat paths. There is, of course, a limit to this regu tery connections. Immediately, both of the lating action and the envelope shape shown in tuned 'circuits begin to build up» oscillations at a Fig. 3 illustrates a case where there is insufñcient very high rate, the initial impedance of element 35 being high. As the impedance of element 35 25 regulation and the signaling voltage is entirely eliminated when the grid potential decreases to decreases, the feedback decreases until a point of or beyond the cut-off value. stability is reached. `rI‘hereafter the element 35 The useful output voltage may be obtained by tends to` compensate for any changes which af directly connecting the load to the terminals lll fect the amplitude of oscillation, for instance, changes in load, battery Voltage and, within 30 and 42; or if greater output or better regulation is required, an intermediate amplifier may be limits, the amplification provided by the tube. A provided. The effective length of each period of similar impedance element may be connected signaling frequency oscillation is slightly less than across winding 2i to compensate for such changes the length of the positive half cycle of the inter in amplitude of the oscillations at the interrupt ing‘frequency. Although it is believed to be pre 35 rupting frequency due to a change in frequency during the build-up and decay of the signaling ferable to operate the oscillator with zero grid voltage. The effective duration of the signaling bias„as shown in the drawing, satisfactory op voltage is illustrated in Fig. 2. eration is obtained by providing a negative grid The advantages of the above-described oscil bias,> inlconventional manner. With zero grid bias,'the signaling frequency is interrupted dur 40 lator over known methods of generating a signal ing voltage of desired frequency and periodically ing the positive half cycle of the interrupting fre interrupting this voltage at a desired rate reside quency; and with a negative grid bias, the sig in its simplicity, its low initial cost, and the low nalingyfrequency is interrupted during the nega cost of maintenance Which results in part from tive ' half-cycle of the interrupting frequency. the lack of moving parts. When the grid bias is zero, there is current in the What is claimed is: grid-cathode circuit during the positive half 1. A signaling -current generator comprising a cycle of the interrupting frequency; and, with a single thermionic tube, two tuned circuits in the low enough ratio between the amplitudes of the signaling and interrupting frequencies, the drop inpotential in resistor I9 is effective to substan anode-cathode circuit of said tube, one of said 50 tuned circuits resonant at a desired signaling fre tially prevent variation in the grid potential due quency, the other of said tuned circuits resonant to the signaling frequency so that oscillation at the signaling frequency ceases. With zero grid bias, there is no grid current and no drop; in po tential in -resistor I9, during the negative half cycle of the interrupting frequency and the am pliñcation of the tube is sufñcient to maintain oscillation at the signaling frequency. If a source of negative grid bias is provided in the con trol grid-cathodecircuit, the instantaneous po tential of the grid varies under control of the feedback potentials; and in this case, there is no grid current and no drop in potential in resistor I_ 9 except during excessive peaks in the sum of the at a desired lower frequency, feedback connec signaling frequency, a network tuned to reso nance at a desired lower frequency, said net works connected in the anode-cathode circuit of said tube, feedback connections from said net instantaneous' feedback potentials of both fre v works to the control grid of said tube, means quencies. ' With sufficient regulation provided by element 35, such excessive peaks will not occur or will not 'be` suiñciently long in duration to sup press oscillation at the signaling frequency dur controlling the relative amplitude of the feed back from said networks to effect a periodic in terruption of the oscillations of said signaling frequency at said lower frequency, output ter lminals, and> means connecting'said terminals to thenetwork tuned to the signaling frequency. ing' positive half-cycles of the interrupting fre quency; but, during the negative half-cycles, the grid potential is driven to and beyond the oscil lation cut-off point by the energy stored in the circuit which is resonantv at the interrupting fre quency. Whenlthis storedl energy is dissipated tions frorn said tuned circuits to the control grid of said tube, and means controlling the relative amplitude of the feedback from said tuned cir cuits to effect a periodic interruption of the oscil lations of said signaling frequency at said lower frequency. 2. In an oscillation generator, a single Vacuum tube, a network tuned to resonance at a desired 3." In an oscillation generator comprising a single vacuum tube, two tuned networks con nectedin the anode-cathode circuit of said tube, each-of said networks .comprisingan inductive 2,409,620 5 6 winding and a condenser, one of said networks being resonant at a desired signaling frequency,‘ the other of said networks being resonant at a desired interrupting frequency, feedback con nections from said networks to the control grid 6. In an oscillation generator comprising a single vacuum tube, two tuned networks con nected in the anode-cathode circuit of said tube, each of said networks comprising an inductive winding and a condenser, one of said networks of said tube, means controlling the relative am .being resonant at a desired signaling frequency, plitude of the feedback from each of said net the condenser of said other network being vari works to effect a periodic interruption of the able so that the frequency at which said other oscillations in said one network at said inter network is resonant may be adjusted within de rupting frequency, and an impedance element sired limits, feedback connections from said net having a negative impedance voltage coefficient works to the grid of said tube, means controlling shunting a part of the inductive winding of the the amplitude of the feedback from each of said network which is tuned to said signaling fre networks to effect the periodic interruption of quency, thereby to regulate the amplitude of the the oscillations of signaling frequency at the oscillations of the signaling frequency. 15 frequency to which said other network is reso 4. In an oscillation generator comprising a nant, output terminals connected to said one single vacuum tube, two tuned networks con network, and an impedance element having a negative impedance-voltage coefficient connected nected -in the anode-cathode circuit of said tube, each of said networks comprising an inductive to the inductive winding of said one network to winding and a condenser, one of said networks 20 regulate the voltage impressed across said ter being resonant at a desired signaling frequency minals. ` and the other of said networks being resonant at 7. In an oscillation generator comprising a a desired interrupting frequency, an adjustable single vacuum tube, two tuned networks con feedback connection from said one network to the nected in the anode-cathode circuit of said tube, control grid of said tube, an adjustable feedback 25 a ñrst one of said networks comprising one wind connection from said other network to the con ing of an induction coil and a condenser, said trol grid of said tube, output terminals connected first network being resonant at a desired low fre to the inductive winding of said one network, quency, the second one of said networks coin and an impedance element having a negative im prising windings of an induction coil and a con pedance-voltage coeñicient connected to the in 30 denser, said second network being resonant at ductive winding of said one network to constitute a desired signaling frequency, means comprising a voltage regulating load. Y ‘ another winding of the first-mentioned induction 5. In an oscillation generator comprising a coil `and a potentiometer connected across said other winding for impressing an alternating po single vacuum tube, two tuned networks con nected in the anode-cathode circuit of said tube, 35 tential of said low frequency on the control grid each of said networks comprising an inductive of said tube, means comprising a potentiometer and a condenser connecting said potentiometer winding and a condenser, one-of said networks being resonant at a desired signaling frequency, in series with said second network for impressing an alternating potential of said signaling fre desired interrupting frequency, feedback connec 40 quency on said control grid, output terminals tions frorn said networks to the grid of said tube, connected to said second network, and means a high resistance connected in the grid-cathode including an impedance element having a neg circuit, means controlling the amplitude of the ative impedance voltage coefficient connected feedback from each of said networks to eifect across one of the inductive windings of said the periodic interruption of the oscillations of second network for regulating the amplitude of said signaling frequency at said interrupting fre the oscillations of said signaling frequency, quency, output terminals connected to said one whereby said oscillations are interrupted peri the other of said networks being resonant at a network, and an impedance element having a negative impedance-voltage coefficient connected odically at said low` frequency and the voltage impressed across said terminalsv is maintained at across a part of the inductive winding of said 50 a desired amplitude. one network. WALTER W. FRITSCHI.