US1349252A - Method of and means for utilizing thermionic currents - Google Patents

Description

H. D. ARNOLIL.

METHOD OF AND MEANS FOR UTILIZING THERMIONIC CURRENTS,

APPLICATION FILED MAR. 20. I916. RENEWED MAY 16. ms.

1 349, 25 2 Patented Aug. 10, 1920.

I VIIIIHIYI ln ven for: Hare/d 0. Arnold UNITED STATES PATENT OFFICE.

HAROLD D, ARNOLD, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD OF AND MEANS FOR UTILIZING THERMIONIC GURRENTS.

Specification of Letters Patent.

Patented Aug. 10, 1920.

Application flled' March 20, 1916, Serial No. 85,362. Renewed May 16, 1918. Serial No. 235,043.

To all whom it may concern Be it known that I, HAROLD DEFOREST ARNOLD, a citizen of' the United States, residing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Methods of and Means for Utilizing Thermionic Currents, of which the following is a full, clear, concise, andkexact description.

This invention relates 0 thermionic amplifiers, and more particularly to circuit arrangements by which the current iroltage characteristic is made to have a desired form.

An object of the invention is to repeat or amplify electrical impulses substantially without distortion.

This-is accomplished by providing a thermionic'device wherein the curve which represents the relation between the input voltage and the output current is approximately straight.

A further object of the invention is to efficiently transfer electrical impulses, employing a thermionic device.

This is accomplished by properly proportioning the internal output circuit impedance with respect to the external output circuit impedance of the thermionic device.

This invention will be explained more in detail in connection with the drawings in. which Figure 1 represents a thermionic amplifier and its circuit, and Fig. 2 a curve by means of which its operation will be exp ained. Figs-3 re resents the same thermionic element modified in accordance with this invention, and Fig. 4 a curve which will be used to explain its operation. Fig. 5 represents another modified circuit for the thermionic element of Fi 1.

Referring to Fig. 1, a t ermionic vacuum tube is shown containing the filament F, input electrode or grid G, and anode or plate P. In the input circuit of this ele ment is laced a battery C, whose function is to malntain the. electrode G at a negative potential with respect to the filament and also to aid in fixing the point on the characteristic at which the amplifier is to be worked. The ob'ect of maintaining the grid negative wit respect to the filament is to insure that no current shall flow from grid to filament and consequently that the input circuit shall have a very ;h1gl1 resistance which shall be independent of the input voltage. The battery B in the output circuit serves to provide the space current from anode P to cathode F, whose variation is utilized to produce the amplified signals.

F,-ig. 2 represents the operation of the ainplifier 0t Fig. 1. In this figure abscissae E,.'represent voltages of the battery C, and ordinates I represent values of current in the output circuit. The curve shown is the one which is obtained with the amplifier as used in ordinary operation, and it will be noted that its curvature is sufliciently lar e to produce distortion or rectification in t e signals produced by a -variation of input voltage E An object of this invention is to render the characteristic of Fig. 2 approximately straight throughout the operating range while maintaining the ratio of amplification at a sufficiently large value.

Fig. 3 shows the amplifier of Fig. 1 connected in amodifiedcircuit. In this figure an additional resistance R has been shown added in the output circuit and the electromotive force of the battery B has been modified in accordance with conditions to be explained later. The electromotive force of the battery C may also need to be modified. The curve in Fig. 4 shows the form of the characteristic when these changes have been made. If in the amplifier of Fig. 1 a resistance R approximately equal to the normal internal resistance of the tube is added in the output circuit, the effect will be to render the characteristic approximately straight but at the same time to greatly lower the current which flows in the output circuit. To raise this current to its normal operating level, it will be necessary to increase the electro'inotive force of the battery B, and therefore to increase the space current. It is therefore necessary, in order to secure an approximatel straight characteristic and also a desire value of output current, to insert in the output circuit a resistance of the order of ma itude of the internal resistance of the tu and at'the same time to vary the electromotive force of battery B in order that the output current may remain fixed at a predetermined value. When these adjustments. have been made, operation wil take place at an approximately straight part of the characterput circuit and istic curve and to the left of the current axis in the region of constant input impedance, and at the same time the ratio of amplification is maintained suiliciently high.

While the resistance has been shown as connected directly in the output circuit of Fig. 3, it is to be understood that the invention is broader than this and that the re sistance may be inserted in other ways. It may, for example, be carried into this output circuit by means of a transformer. That is, if as shown in Fig. 5, the resistance R, is actually included in the secondary circuit of the output transformer, it will produce an effective resistance in the primary circuits yielding, same result as if a resistance had been actually placed in this primary circuit. The value of the effective resistance produced in said primary by a given resistance in the secondary circuit will, of course, depend on the ratio of transformation of theotransformer.

What is claimed is:

1. A thermionic amplifier having an input circuit and an output circuit, a source of electromotive force in each of said circuits, and a resistance in said output circuit, the ma nitude of said electromotive forces and 0 said resistance being so related that the output current shall vary approximately linearly as the input voltage over a portion of the characteristic curve suitable for eflicient'operation of said amplifier.

2. A thermionic amplifier having an input circuit and an output circuit, a source of electromotive force in each of said circuits, and a resistance in said output circuit, said resistance being of such a. magnitude that the output current shall vary approximately linearl as the input voltage and said electromotive forces bein of such a magnitude as to secure a desired value of said output current.

3. A thermionic amplifier having an input circuit andan output circuit, a source of electromotive force in each of said circuits, and a resistance in said output circuit, said resistance being of such a magni tude that the output current shall var approximately linearly as the input vo tage, said electromotive forces being of such a ma nitude as to secure a desired value of sai output current, and to maintain a high input circuit impedance.

4. A thermionic amplifier having an inan output,circuit, a source of electromotive force in each of said circuits, and a resistance in said output circuit, said resistance being approximately equal to the normal internal resistance of the tube for the purpose set forth.

5. A thermionic amplifier having an input circuit and an output circuit, a source to all intents and purposes, the

the tube whereby the output current shall vary approximately linearly as the input voltage, said electromotive forces being of such magnitudes as to secure a desired value of said output current, and'to maintain a high input circuit impedance.

, (5. A thermionic device having an input circuit and .an output circuit, a resistance in said output circuit, said resistance being of the same order of magnitude as the internal impedance of the said device.

7. A thermionic device having an input circuit and an output circuit, the resistance of said output circuit external to said device being of the same order of magnitude as the internal impedance of the said device.

8. A thermionic device having an input circuit and an output circuit, a resistance in said output circuit external to said device, said resistance being of the same magnitudeas the internal impedance of the said device.

9. A thermionic repeater having cathode,

, anode and' control electrodes, means for supplying current between said cathode and anode, means connected to said cathode and control electrode for impressing thereon alternating currents to be repeated, and an output circuit connected to said cathode and anode, said output circuit having an impedance such that said alternating currents are repeated substantially without distortion.

10. A thermionic device wherein the curve which represents therelation between input voltage and output current is approximately straight.

11. A thermionic repeater having an input circuit and an output circuit, said output circuit external to said repeater havin an impedance such that the curve whic represents the relation. between input voltage and output current is approximately straight.

12, A thermionic repeater having an input and\a n output circuit, said output circuit externalto said repeater having an. impedance of the same order of ma n'ltude as the internal impedance of the sai repeater.

13. A thermionic repeater having an input and an output circuit, saidv output circuit external to said repeater having a resistance at least as large as the internal impedance of the said repeater.

14. A thermionic repeater having an input and an output circuit, said output circuit external to said repeater having an impedance at least as large as the internal impedance of the said repeater.

15. A thermionic repeater having an input circuit and an output circuit, a source of electromotive force in each of said circuits, said output circuit havin an impedance, the magnitude of said e ectromotive forces and said impedance being such as to cause the output current to vary approximately linearly as the input voltage over a portion of the characteristic curve suitable for efficient operation of the said repeater.

16. A thermionic device having an input circuit and an output circuit, means for maintaining substantially an infinite impedance for said input circuit, the curve which represents the relation between the input voltage and output current of said device being approximately straight.

17. A thermionic amplifier having cathode, anode and control electrodes, means for supplying between said cathode and anode a current the variation of which with voltage is substantially constant, means connected to said cathode and control electrode for impressing thereon alternating currents to vary the discharge between cathode and anode within a range corresponding to that part of the volt-ampere characteristic of said amplifier that exhibits no substantial departure from a straight line, and an output circuit connected to said cathode and anode. i

18. The method wherein is employed a thermionic device comprising a hot cathode and a control electrode for amplifying a variable electric current without distortion which comprises producing from said cathode an electron discharge the variation of which with voltage is substantially constant, and applying the input current to produce corresponding electromotive forces across said cathode and said control electrode, thereby varying said discharge within the range'for which the ratio of current increment to voltage increment remains substantially constant.

19. The method wherein is employed a thermionic device com rising a hot cathode and a grid for ampli ying a variable electric current without distortion which comprises producing from said cathode an electron discharge the variation of which with voltage is substantially constant, substantially infinitely impeding the input current and applying the input current to produce corresponding electromotive forces across said cathode and said grid, thereby var ing said discharge within the range which the ratio of current increment to voltage increment remains substantially constant. V

In witness whereof I hereunto subscribe my name this 18th day of March, A. D. 1916.

HAROLD D. ARNOLD.

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