US2438382A - Oscillation generator - Google Patents

Description

March 23, 1948.

L. w. BORN OSCILLATION GENERATOR Filed May 5, 1945 INDUCTII/E REA cTA/vcE INVENTOR [0 W EORN ATTORNEY Patente d Mar. 23, 1948 OSCILLATION GENERATOR Leo W. Born, Collingswood, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application May 5, 1945, Serial No. 592,091

Claims. (Cl. 25036) This invention relates to an oscillation generator, particularly of the type in which an electron discharge tube is used in combination with circuit components forming a master oscillator.

The problem of obtaining frequency stability in an oscillator has been encountered at all stages in the development of the art. Various solutions have been offered by engineers in the past. Some of these solutions involve very complex circuit arrangements; others are critical in their adjustments.

It is, therefore, an object of my invention to provide a very simple oscillation generator circuit which possesses self-regulating features.

It is another object of my invention to provide a circuit arrangement for an electronic oscillation generator in which the effects of one resonant circuit shall counteract those of another resonant circuit in the event that the circuit as a whole may tend to depart from a desired frequency setting.

My invention will now be described in more detail, reference being made to the accompanying diagram, the sole figure of which represents a preferred circuit arrangement whereby the invention itself may be carried out.

Referring to the drawing, I show therein a conventional triode electron discharge tube I. Connected between the cathode and the grid of this tube is a part-section of an inductance 2 in series with a resistor 6, the latter being shunted by a capacitor 1. The terminals of the full inductance coil 2 are connected across a tuning capacitor 3, thus forming a parallel tuned resonant circuit 2, 3. At one end of this resonant circuit is a ground connection and also a connection to the negative terminal of a direct current supply source 8. The positive terminal of this source is connected through a choke impedance 9 to the anode of the tube I.

In shunt connection with the parallel tuned circuit 2, 3 I also provide a series resonant circuit comprising an inductance 4 and an adjustable capacitor 5.

The output from this oscillation generator may be taken off through terminals l0, one of which is coupled to the anode through a capacitor II and the other of which is grounded.

In order to appreciate the features of my invention which are considered novel and useful it should be understood that it is important to tune the series resonant circuit 4, 5 to a frequency somewhat higher than that of the oscillation generator per se, altho tuning the series circuit to a lower frequency will provide the same advantages of operation, only to a lesser degree. The circuit cannot, of course, be made to oscillate at the resonant frequency of the series circuit itself. The series resonant circuit 4, 5 is an efiective capacitive reactance with respect to which the parallel resonant circuit 2, 3 is an effective inductive reactance equal in magnitude at the operating resonant frequency.

Now if for any reason the constants of the circuit are varied within certain limits such as by an increase in tube capacity due to heat, the frequency would ordinarily tend to decrease, which would reduce the inductive reactance in the parallel resonant circuit 2, 3. At the same time, however, a compensating increase in the capacitive reactance of the series resonant circuit 4, 5 would take place. The net result would be that the frequency of the oscillation would be altered very slightly compared with the frequency deviation in the absence of the series resonant circuit 4, 5.

Viewing the problem in a different manner, the admittance curve of the circuit 4, 5 when added to that of the circuit 2, 3 produces a resultant curve of total admittance which has a much greater slope than either of the individual curves. The increase in slope of the combined admittance curve is analogous to an increase in the Q of the circuit. With a high Q circuit, the frequency of oscillation need shift only a small amount in order to produce a considerable change in the reactances.

The circuit as herein'shown and described provides very satisfactory compensation for frequency changes which would otherwise result from changes in the tube capacity, temperature changes in the inductive and capacitive elements and other factors. 7

The precise details of the circuit arrangement as herein illustratively shown and described need not necessarily be adhered to in carrying out my invention. Modifications may well be made by those skilled in the art without departing from the spirit and scope of the invention itself.

What is claimed is:

1. An oscillation generator comprising an elec-.

tron discharge tube having a cathode, an anode and at least one grid, a direct current source having its negative terminal grounded and its positive terminal connected to said anode through an inductive impedance, a parallel resonant circuit connected from ground through a grid resistor to said grid, a capacitor in shunt with said resistor, a conductor interconnecting the cathode and an intermediate point on the inductive eleof the parallel resonant circuit' to" constitute" means for stabilizing the frequency of the oscillator,

3. An oscillator according to claim 2and'having a terminal Ofthe parallel resonant circuit connected to the grid electrode through a grid leak resistor in shunt with a capacitor, the other terminal of said parallel resonant circuit being grounded.

4. An oscillator according to claim 2 and having-a connection'between said cathode electrode and a tap on the inductive winding of saidpa-rallel resonant circuit.

5. In an oscillation generator, an electron dis charge tube having a cathode, an anode-likeelectrodeand a control electrode, a parallel resonant circuit having a capacitive branchand an inducnant circuit is tuned.

4 tive branch and having one terminal coupled to said control electrode, means coupling the oathode of said tube to a point intermediate the terminals of said parallel resonant circuit, a coupling between the other terminal of said parallel resonant circuit and the anode of said tube, and

a series resonant circuit comprising, inductance and capacity in shunt with said parallel resonant circuit, saidseries resonant circuit having its inductive and capacitive elements adjusted to produce resonance at a frequency somewhat higher than the frequency at which said parallel reso- LEO W. BORN.

REFERENCES CITED The following references are of record in the file "of this patent:

UNITED STATES PATENTS Number Name Date" 7 1,621,992 Meissner' s Mar; 22,1927 2,048,723 Appleton July'28, 1936 2,243,540 'Se'eley' May'2'7, 1941 2,305,262' 'Liange Decg15j1942 2,391,386 J Bradley; Dec; 25; 1945 v i FOREIGN PA ENTS Number- Country iDate- France "Q0611, 31, 1924

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