US1711969A

US1711969A - Thermionic device

Info

Publication number: US1711969A
Application number: US557918A
Authority: US
Inventors: Round Henry Joseph
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1921-05-18
Filing date: 1922-05-02
Publication date: 1929-05-07
Anticipated expiration: 1946-05-07
Also published as: GB187646A; NL14137C

Description

y 1929. H. J. ROUND 0 1,711,969

THERMIONIC DEVICE Filed May 2. 1922 Fly? Fig 3 Fig. 1

Umjowf [arm/7f //7,01// 3 E 00/,60/ lwmm HENRY JOSE PH ROUND izy 41M Patented May 7, 1929.

s 1,711,96il

UNITED STATES, PATENT oFFica' HENRY JOSEPH ROUND, LONDON, ENGLAND, ASSIGNOR TO RADIOCORPORATION' OF AMERICA, A CORIORATION DELAWARE.

THEBMIONIC DEVICE.

Application filed May 2, 1922, Sieria1 No. 557,918, and in Great Britain May 18, 1921.

It is well known that the relation between the space current and the voltage applied to a thermionic device or vacuum tube is usually not linear and is at the best never linearover more than a very small-range.

7 It has been shown that in a vacuum tube of should'be of the linear form i=7cV over a large range. This is particularly so when a three electrode tube is used for voice magnification; Also when a two or three electrode valve is used in combination with an independent oscillator as inthe well knownheterodyne method, it is advisable to use a rectifier which has this straight line law sothat isig nals appearing simultaneously do not tend to distort one another, and when a, three electrode tube is used for the introduction of negative resistance in the well known way a straight line lawis desirable. Also when a valve circuit is arranged to give a certain frequency of oscillations, straight line laws of the characteristic of both anode and'grid circuits are desirable.

According to this invention there is'introduced into the anode circuit of a tube a resistance which is large compared with the resistance of the tube so that the voltage current relation of this combined system is mainly controlled by the resistance, and then, since the slope of the characteristic is very much less,'severalof these tube resistance systems are arranged in parallel so that the characteristic of the whole combination is given any required slope.

Both theoretically and experimentally it is found that the result is a characteristic which has its curvature reduced in proportion tothe number of tubes used and to the resistance placed in series with each tube, the larger the resistance, and the greater the number of tubes, the straighter the characteristic.

Such a combination can be then used as a unit just as one tube is used.

In some cases the anodes of two or more tubes may be connected-to a single resistance if the characteristics of such tubes are the same.

In some cases also a resistance of high value may be inserted into the grid circuit of a three electrode tube in addition to the resistance in the anode circuit. i

' My invention is illustrated by the .acc'om:

panying drawings, in which: I

Fig. 1 1s a series of curves showing the rider tion between input voltage and out-put current. I

' Fig. 2 is a diagram of an arrangement in accordance with my invention, and Fig. 3 is a modification' f i V Figs.-4 .and 5, are diagrammatic representai tions of circuits embodying the invention for certain purposes; v 1

In Figure l curve Arepresents thee-harm teristic of a two electrode valve, and curve (B represents the characteristic of a resistance. By merely adding thevoltages at equal currents we get the characteristic C ofthe series coinbin'ation'of thevalve and resistance which isoffliess slopethan either curve A or curve B,

and byinultiplying,all; ordinates by three we get,thecharacteristic'oi three of these combinations in parallel, noticeably a longer and stralghter curve than the original single valve arrangement. i

The arrangement is shown in Figure 2 where V, V, are three diodes or two electrode devices arranged in parallel with a resistance R in series" with the anode of each.

It is obvious that if all the three valves are exactly similar in characteristics the result is equally well obtained by the arrangement shown in Figure 3 where the one resistance R is equal to one-third of any of the resistances Rin Figure 2.

A much longer and straighter characteristic still can be obtained by using more valves in parallel with high resistances in series with each.

No modification of this arrangement need be made if the diodes be replaced by'triodes istic similar to that of a French standard receiving valve and with 150,000 ohmsin series with it may be arranged in parallel. The result is a characteristic which has about the same slope as the one valve at its best but this slope is maintained with about one twelfth the curvature for twelve times the length.

"Such an arrangement may be employed for the magnification of voice currents asshown in Figure 4c, in which the inputtelephone is coupled through transformer T to the parallel connected grids of the five valves V Resistances R are connected in series with each of the anodes of the valves, and an output transformer T is connected to the tubes which are in parallel. As shown in Fig. 5, the arrangement may be used as a constant wave length heterodyne, or as a reaction cir' cuit of low damping acting as a filter between input and output circuits. The arrangement comprises a plurality of three electrode tubes V having resistances R connected as in Fig. 2. The input circuit is coupled to an oscillatory circuit 0 which is also coupled to the out-put circuit. The input circuit of the valves is connected across the condenser of the oscillatory circuit and the output circuit of the valves is coupled through coil P to the inductance of the oscillatory circuit forming a re enerative or feed back circuit. This circuit may act as a heterodyne or a reaction circuit depending on the adjustment of the coupling to produce amplification or generation of oscillations. In this case high resistances R are inserted in series with the "grids. In paralleling a large number of valves for transmission it is advantageous to introduce these separate resistances and the larger the number of valves, the greater these resistances can be Without the overall loss reducing the efiiciency seriously, providing the valves are made to stand high voltages.

Having described my invention, what I claim is:

1. Amplifying means for incoming electrical cnerg comprising a plurality of three electrode thermionic devices in parallel, each of said devices having input and output sides, individual means in each of said outputs for accentuating the linear characteristics of said devices when used in combination, said means also serving to equalize the operating characteristics of said devices, and means in said output circuit i'or ai'lecting each of said devices equally in accordance with said incoming energy.

2. Means for controlling the flow ofelec trical energy in circuit, comprisin a plurality of parallel paths each of which'contains an electron discharge device, means for equally varying the conductivity of each of said devices in accordance with said flow, and means in the anode circuit of each of saiddevices for accentuating and equalizing the linear characteristics of said devices when used in combination. g

I 3: Amplifying means for electrical energy, comprising a plurality of thermionic devices connected in parallel, and individual means in the anode circuit of each of said devices for equalizing the constants of said devices and accentuating the linear characteristics thereof when used in combination.

HENRY Josiirn ROUND. i