US1540578A - Means for producing oscillations - Google Patents

Description

June 2, 1925. 1,540,578

. H. C. THOMPSON MEANS FOR PRODUCING OSCILLATIONS Filed July 1, 1921 [rm/enter Hay-ivy; CgThom son,

by His Attorney.

Patented June 2, 1925.

- UNIT En STATES PATENT oer-"ice.

HARRY C. THOMPSON, O'F' SCHEIJEGTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORIE'QRATION OYF NETW $503K.

MEANS FOR PRODUCING OSCILLATIDNS.

Application filed July 1,

To allwhom it may concern:

Be it known that I, HARRY Cl THOMPSON, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Means for Producing Oscillations, of which the following is a specification.

My present invention. relates to means for producing oscillatory currents and more particularly to-the application oi? electron discharge apparatus for this purpose.

The object oi my invention'is to provide a simple and: eiiicient arrangement for producing oscillatory currents by means of an electron discharge device of the dynatron or negative resistance type.

A more specific object of my invention is to provide an. improved circuit arrangement for producing oscillatory currents by. means of a system and apparatus of the, general type described in Hull Patent 1,313,188 of August 12, 1-919.

In that patent an electron discharge device is described having an electron emitting cathode and two other electrodes enclosed in. an evacuated receptacle. Sources of potential are applied between the cathode and the other electrodes of such value that a sufficient emission of secondary or impact electrons will be' effected from. one of the other electrodes to produce a negative resistance characteristic in the circuit between the cathode and that electrode. This circuit is an oscillatory ci roi'iit and it the resistance is of the proper value with respect to the inductance and capacity of the circuit oscillatory currents will automatically be produced therein the frequency oi which will be determined by the constants of the circuit. The alternating currents produced may be supplied to a utilization circuit by coupling an inductance in the utilization circuit to the inductance of the oscillatory circuit.

It is now known that the oscillatory currents; producedby such an arrangement may equally well be supplied to a utilization circuit by coupling such circuit to. the circuit between the cathode and the electrode which receives the impact electrons from the elec' trode by which they are emitted. In such case the amount of energy which circulates inthe oscillatory circuit may be very small,

1921-; Serial No. 481,979.

as. all that the oscillatory'energy has to accomplish is to vary the potential of the electrode to which. it is connected with. respect to'the cathode. In the arrangement shown in: the Hull patent referred to, the average potential of this electrode with respect to the cathode is maintained positive by the use of a direct current sourceof potential having its positive ternrinal connected to the electrode which emits impact electrons, and its negative terminal connected tothe oathode. I have discovered, however, that when the utilization circuit is. coupled to the circuit of the electrode which receives the impact electrons, greater efliciency in operation may be obtained by maintaining the average potential of the electrode which emits impact electrons negative with respect to the cathode.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization andmethod of operation will best be understood by reference. to the following description taken in connection with the accompanying drawing in which. I have indicated diagrammatically one circuit organization whereby my invention may be carried into effect.

As shown inthe drawing, I provide an electron discharge device 1 having an electron emitting cathode 2, a second electrode 3 and a third electrode at, which is interposed between the cathode 2 and the electrode 'lhis electrode 4 may be in the form of a grid or it may be made in any other desired form of construction which will permit of the passage ofelectrons between the cathode 2 and elect-rodeB, and will also be capable of producing a desired electrostatic field between those electrodes. The electrode 3 is maintained at a fairly high positive potential with respect to the cathode 2 by means of a direct current source 5, which is included in. the circuit between these electrodes. The value of the potential. required will depend largely on the construction. of the device. In some cases itmay be'as low as 300 volts while for other devices potentials as high as 1000 volts'may be necessary. The circuit between cathode 2 and electrode 3 is an oscillatory circuit which comprises. in-

be supplied to the circuit.

from the description set forth in Hull Patent 1,313,188. It will be apparent that when oscillations are produced in the oscillatory circuit the potential of electrode 4 with respect to that of cathode 2 will alternately become more positive or more negative than normal. When the electrode 4 is negative With respect to the cathode no electrons will be received thereby and no energy will be supplied to the oscillatory circuit. hen it is positive with respect to the cathode it will receive electrons therefrom and energy will As it becomes more positive the impactelectrons will be emitted from the electrode 4 in sufficient number. so that the net current flowing to the electrode 4 will reverse in direction. All that is necessary in order to maintain the oscillatory current in the circuit is that the energy supplied to the circuit when the direction of the current reverses, will be some-v what greater than the energy supplied to the circuit before the current reverses in direc tion.

The interval of time required to supply to the circuit the energy necessary tomaintain oscillations may be short in comparison with the period of the oscillations. It is therefore possible to maintain the electrode 4 at a negative potential with respect to the cathode during a greater portion of the time than that during which it is positive, and I have found that in a system such as that illustrated more etficient results may be obtained when the average potential of the electrode 4 with respect to the cathode is maintained negative, as by means of the direct current source 8. All that is necessary to start the production of oscillations in the system described is to give to the electrode 4 in any suitable manner a momentary positive charge, and when the production of oscillations is once started in this way it will be automatically maintained by reason of the fact that the potential of the electrode 4 will alternately become positive and negative with respect to the cathode 2.

It will be evident that the current flowing in the circuit between the cathode 2 and electrode 3 whether-it be considered as produced mainly by means of electrons emitted from the cathode 2 or by the combination of such electrons with the impact electrons emitted from the electrode 4 will vary in accordance with the variations in the potential of elec trode 4. It is therefore apparent that the current in this circuit between cathode 2 and electrode 3 will pulsate and that oscillations of'the same frequency as those set up in the circuit 6, 7 may be supplied by means of a coupling transformer 9 to a utilization circuit 10 of any form desired.

.VVhile I have shown and described the simplest embodiment of my invention it will be apparent that my invention is by no means limited to the particular embodiment shown but that many modifications in thetype of apparatus employed as well as in the circuit connections used may be made without departing from the scope of my invention asset forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. Means for producing oscillations comprising an electron discharge device having an electron emitting cathode and at least two other electrodes, an oscillatory circuit connecting the cathode and one of the other electrodes, a circuit connecting the cathode and a second electrode and containing a source of potential of such value as to permit of the effective emission of impact electrons from the first electrode in sufficient amount to produce a negative resistance characteristic in the circuit connected thereto over a range of positive potential of the first electrode, and means for maintaining the average potential of the first electrode negative with respect to the cathode.

2. Means for producing oscillations comprising an electron discharge device having an electron emitting cathode and at least two other electrodes, an oscillatory circuit connecting the cathode and one of the other electrodes, a circuit connecting the cathode and a second electrode and containing a source of potential of such value as to permit of the effective emission of impact electrons from the first electrode in sufficient amount to produce a negative resistance characteristic in the circuit connected thereto over a range of positive potential of the first electrode, and a source of direct current potential included in the circuit between the cathode and the first electrode having its positive terminal connected to the cathode.

3. Means for producing oscillations comprising an electron discharge device having an electron emitting cathode and at least two other electrodes, an oscillation circuit connected between the cathode and one of the other electrodes, means for producing an emission of impact electrons from the electrode to which the oscillatory circuit is connected suflicient to produce a negative resistance characteristic in that circuit over a range of positive potential of the electrode connected to the oscillatory circuit, and means for maintaining the average potential of the electrode to which the oscillatory circuit is connected negative with respect to the cathode.

4. Means for producing oscillations co1nprising an electron discharge device having an electron emitting cathode and at least two other electrodes, an oscillation circuit connected between the cathode and one of the other electrodes, ieans for producing an emission of impact electrons from the 1 electrode to which the oscillatory circuit is connected sufiicient to produce a negative resistance characteristic in that circuit over a range of positive potential of the electrode connected to the oscillatory circuit, and a source of direct current potential included in the oscillatory circuit having its positive terminal connected to the cathode. a?

In Witness whereof, I have hereunto set my hand this 30th day of June, 1921.

HARRY C. THOMPSON.

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