US1981115A - Vacuum tube - Google Patents

Description

E. G. MURPHY VACUUM TUBE Nov. 2o, 1934.

Filed Deo. 14, 1928 2 Sheets-Sheet l Z1/gaz A I jay/.4

NOV.y 20, 1934. E G MURPHY 1,981,115

VACUUM TUBE Filed Deo. 14, 1928 QSheets-Sheet 2 'nu .u

Patented Nov. 20, 1934 vUNITED STATES PATENT OFFICE 3 Claims.

This invention which relates to'vacuum tubes or electron discharge devices is a continuation in part of and an improvement'over the subject y matter of my copending application, Serial No. l 73,822, led December 7, 1925, for Vacuum tubes and patented as Patent 1,699,011, Jan. 15, 1929.

The main object of the invention is to provide an improved vacuum tube with novel self-inclosed adjustable means whereby the tube may be operated on those points of the locus of the characteristic curves thereof that will result in maximum circuit eiliciency in radio transmitting and receiving.

Another object is to provide a vacuum tube with adjustable insertable means for the variable control and regulation of the electrodes therein independently of external apparatus.

A further object is to provide a vacuum tube with self-inclosed adjustable means for varying the potential or bias to be applied to the grid electrode of the tube.

More particular and special objects of the individual tubes and the various modifications herein disclosed will be set forth in separate paragraphs in the details hereinafter set forth, reference being had to the accompanying drawings in which:

Figure 1 is a side elevation of a vacuum tube embodying my invention;

Fig. 2 is a vertical sectional view of Fig. 1;

Fig. 3 is a vertical sectional view of a slightly -modied form of the tube shown in Fig. 2, il-

lustrating the use of an insertable potentiometer for f'lne adjustment of potential to one of the electrodes or for stabilizing the circuit;

Fig. 4 is a. diagrammatic view of the circuit embodied in the tube shown in Fig. 3;

f Fig. 5 is an enlarged longitudinal sectional view of one of the insertable cartridge resistance units;

Fig. 6 is a modification of the form shown in Fig. 3;

Fig. 7 is a modified form of the invention showing the control of the grid electrode by a combination cartridge condenser and grid leak;

` Fig. 8 is a modification of the form of the 'invention shown in Fig. 2, with insertable means for varying the output impedance of the tube;

Fig. 9 is a combination tube showing adjustpedance of the tube, and a xed value insertable cartridge resistance unit for the control of the lament;

1 ,Fig 10 is an enlarged longitudinal sectional view of a combination cartridge condenser and able insertable means for varying the output im- (Cl. Z50-27.5)

grid leak employed in the tube illustrated in Fig. 7:

Fig. 11 is a transverse section taken on line 11-11 of Fig. 10;

. Fig. 12 is an enlarged longitudinal sectional view of a fixed value cartridge resistance unit employed in the tube illustrated in Fig. 9;

Fig. 13is an elevational View of the exterior ofA a modified form of tube showing an enlarged base for the reception of heavy duty cartridge units; and

Fig. 14 is a longitudinal sectional view of a cartridge potentiometer unit as employed in the tubes shown in Figs. 3, 4 and 6.

In the drawings wherein similar characters of reference indicate corresponding parts in the several views of the preferred forms of my invention, A designates a glass envelope secured to a base B having a subsocket 15 to be described more fully elsewhere in the present specification. Formed integrally with the envelope is the press 16 in which are imbedded the supporting rod 17 for the cathode 18, the rod 19 for the grid 20, and the rod 21 supporting the anode or plate 22.

In the construction shown in Figs. 1 and 2, one of the electrodes, in this instance the filament, is variably controlled by the insertable cartridge resistance unit C which is clampingly held in the socket members 23, 24 which are formed of short sections of split metal tubing crimped to opposite sides of the wall of the base.

To the bottom of the base B of the tube are secured the circuit-completing prongs which include the filament prongs 25, 26; the grid prong 27 which is connected to the grid electrode by wire 28, and the anode prong 29 which is connected to the anode by lead 30. By inspection of Fig. 2, it will be seen that filament prong 26 is connected by wire 31 to right hand socket member 24 whence the filament circuit may be completed through the cartridge element C which may be slid transversely of the arm 32 secured on the inner bottom of the base of the tube, the arm contacting with resistance winding 33, whereby the resistance and consequently the current fed to the filament 18 via lead 34 attached to arm 32, may be varied.

The resistance cartridge unit C which is employed in the tube shown in Figs. 1 and 2, is shown in detail in Fig. 5. It consists of a tube 35 of glass or other suitable insulating material closed at each end by caps 36, 37 containing p1ugs of fusible metal as, 39 connected ,1-

:may be of any suitable ohmic resistance.

conventional capacity by merely thrusting La short section of metal rod of suitable size into the subsocket 15 in place of cartridge unit C. The provision of a fuse in the cartridge element C is particularly valuable in the case of power and transmitting tubes wherein the' destruction of the lament is a costly matter as the tube is thereby in most cases rendered worthless. The

filament circuit of the tube shown in Figs. 1 and 2 is energized from prong 25, wire 25', rod 17, filament ,18, lead 34, arm .3.2, winding V33, cap 36, metal plug 38, fuse 40, metal plug 39, metal cap 37, socket member 24, wire 3l and prong .26 to battery D or other source of. electrical energy.

In the modification shown in Fig. 3, the circuit of which is shown in Fig. 4, the filament circuit is shunted :by an insertable .potentiometer unit in the form of the cartridge E, the winding of which maybe vconnected to the plate or grid electrodes through the arm 32. The potentiometer E is shown in detail in Fig. 14

' .and comprises a section of `dielectric tubing 41 closed at each end by caps 42, 43 connected by the exterior `inductive winding' 44 which latter In this respect, I have found the use of nichrome wire in practice to offer certain advantages `as a winding for the potentiometer since its resistance is high .enough to permit the use of a comparatively few .turns of wire in order to obtain the desired resistance value. A fifth `prong 45 in the tube illustrated in Fig. 3, may be outwardly connected .to the positive or negative of vthe source Aof plate energization, in this manner .a fine adjustment of the filament-plate potential may be obtained.. This feature is especially desirable in thermionic detectors and particularly so in soft or gaseous thermionic valves which are exceedingly sensitive and responsive to slight Variations of potential. It will be apparent from inspection .of Fig. 4 that the grid return can .be applied to the positive or negative side of the filament battery and that consequently the vgrid `bias can be graduated nely between positive and negative values. In Fig. 4,.by way of eX.- ample, both the plate vand the grid are connected to the potentiometer, but it will be obvious .that either Vthe grid return singly or the plate return singly may be Vapplied to the positive or `negative side of the filament battery or other Lsource of power through one of the prongs 25,

26,-if desired. The lament circuit of the tube shown in Fig. 3, and diagrammatically shown in Fig. 4, is completed from the prong 25, wire 25,-rod 17, `filament 18,V lead 34 to prong.26,- wire 25 and lead 34 being also `connected to socket members 23,24 between which the potentiometer E is secured,-,-this potentiometer as illustrated diaerammatically in Fig. 4 .permitting or shunting a part of the filament current vto iiow through the winding 44 which in this instance. as indicated above, may be of compara- Should the fuse melt, thus breaking .description as that shown in Fig. 3 except that the fifth prong has been eliminated and a binding post 46 substituted,the wiring connections Vin .the `interior of the base otherwise being identically the same. Where it is not desired to -employ five -prong tubes, this form offers an alternative.

In Fig. 7, a combination cartridge grid leak and condenser F is shown which is inserted between the vsocket members 23 and 24 in series with the grid electrode ofthe tube which may be of the usual conventional `structure -so far as the disposition of the envelope, press and electrodes is concerned. The `element, F, as shown in Fig. 10, comprises a tube of dielectric 47 having an inner coating 48 of high resistance metal serving as an electrode grid leak. 'Ihe leak resistance 48 may either be sputtered .on the inner Wall of the glass tube 47, .or it maybe east With the glass .as one of the ingredients of the latten-a number of metallic salts in suitable proportion with the other well known ingredients of glass answering the purpose indicated. A metal plug 49 of fusible metal closing one end of the tube is connected vto the'ends of a number of separated sheets of metal or foil 50 insulated, one from the other b y sheets of paraffmed paper 51, -these sheets of metal being t separated by the paper sheets from other sheets or metal or foil 52 thelatterbeing attached to the .opposite metal plug 53. The metal plugs 49 and 53 are in con-tact with the electron leak resistance 48 which is chosen `of .suitable value and preferably between the usual limits of ,105

and l0rl ohms. Metal caps 54 and 55 at either end of the tubing 47 complete this combination grid leak and condenser which Aas a cartridge may be inserted in the subsocket 15 .of the tube shown in Fig. 7. The grid circuit may now be energized frornprong '27, lead 28', socket member 24, cap 55, metal plug 53, through leak resistance 48 and electrostatically through the sheets 50 and 52 of the condenser element, metal plug l49, cap 54, socket member 23, to lead 28 and grid 20.

Fig. 8 in .its construction, is based substantially on `the form of tube shown in Figs. 1 and 2,--

the cartridge unit C in this modification being inserted in the :subsocket l5 in series with the plate electrode 22 whereby the plate or output impedance of the .tube may be equalized with .the load resistance. As is well known to those skilled in this art, the poweroutput ,of a thermionic valve is greatest when the plate impedance `of the tube or valve Ais madesubstantially `equal'to the load resistance.. noted that in all forms of receiving sets employing vacuum tubes, and particularly thoseL:4

It is also to be circuits employing high frequency oscillation transformers the electrical constants `of which are of uniform value, the use of thermionic valves of vsubstantially .the :same output impedance is nimperative if the maximum possibilities or eiiiciency of the circuit is to be realized. As indicated in Fig. 8, the plate impedance of a series of thermionic valves can be matched, one with the other, assuming the tubes to be of the same type and average capacity. The cir- I cuit of this tube, as illustrated in Fig. 8, so far as the plate circuit is concerned, is completed from prong 29 to clamping socket member 24, cap 37, metal plug 39, resistance strip 40, metal plug 38, cap 36, winding 33, arm 32, lead 22 to anode 22.

Fig. 9 shows a modication embodying a combination of means for controlling the output impedance of the tube and for regulating the filament circuit. The plate circuit of this tube is completed from anode plate 22, wire 32 to socket member 56, cap 37, metal plug 39, resistance strip 40, metal plug 38, metal cap 36, winding 33 and contact arm 57 to prong 29. The means for regulating the filament circuit comprises a xed value resistance unit G, shown in Fig. 12, which is placed in series with the filament. The unit G consists of a section of dielectric tubing 58, closed by metal caps 59, 60 which inclose plugs of fusible metal 61, 62 in which are imbedded the ends of the winding 63 which, in this modification is within the interior of the tubing 58. When the cartridge unit G is placed in the socket members 23, 24, the filament circuit may now be completed from prong 26, socket member 24, cap 60 of element G, metal plug 62, winding 63, metal plug 6l, cap 59, lead 64, filament 18, rod 17, wire 25' to prong 25.

In Fig. 13, a tube is shown wherein the base is enlarged to accommodate comparatively large or heavy-duty cartridge units. The prongs and the immediate lower part of the adjoining bottom of the base of this tube, however, is of conventional construction so that it may be received by any of the standard tube sockets.

If alternating current is employed to energize the lament and plate circuits of these tubes, the modification shown in Fig. 3 is particularly desirable as the objectionable hum especially noticeable in low-voltage alternating current circuits when connected to sound reproducing means-can be almost completely eliminated. This is accomplished by inserting a cartridge resistance element E in the subsocket 15 and then applying a positive potential from the plate energizing source. In this instance, it is assumed that a separate insulated cathode of conventional type is employed in addition to the heating lament. The grid bias in the alternating current type of thermionic valves is, of course, obtained from the alternating current plate current supply by inserting a cartridge resistance of suitable value between the negative pole and positive pole of the filament energizing source and then connecting the grid and plate electrodes as shown in Fig. 4. The correct value of the resistance required is deduced from the IR drop across this resistance, the grid bias required being known from the characteristics of the particular tube, assuming definite plate potentials.

It will be apparent from the foregoing description and illustrations that the invention lends itself to the widest modification and change, and it is accordingly to be understood that the types described are merely representative; hence, I do not coniine myself to the details precisely as set forth but desire to avail myself of such variations and embodiments as fairly fall within the limits of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

l. In combination, an electron discharge device having lament, grid and plate electrodes in an envelope, a base secured to said envelope and means removably insertable in the base including a manually adjustable cartridge potentiometer element electrically connected to the ends of one of said electrodes and to at least one other of said electrodes, whereby when said potentiometer element is moved relatively to a contact connected to one of the electrodes, the filament-plate potential may be varied and simultaneously therewith a variable positive and negative potential selectively applied to the grid electrode.

2. An electron discharge device suitable for alternating current energization comprising an envelope having a plurality of electrodes mounted therein, a base secured to said envelope, circuit completing prongs attached to the base, and means insertable in said base for making operative the electron discharge device, said means including a cartridge inductance movable transversely of a contact member secured within the base and electrically connected to at least one of the electrodes, for negatively and positively biasing, optionally as desired one of the electrodes and varying the potential gradient along another of said electrodes, said prongs being electrically connected to said electrodes.

3. In combination, an electron-discharge device having a plurality of electrodes fastened in an envelope directly secured to mechanical means, an arm secured to said means, a tubular potentiometer slidably engageable with said arm, a pair of clamping memberselectrically connected to at least one of the electrodes and operative to receive said potentiometer Within the said means, and external means for electrically connecting the arm to the potentiometer and thereby to at least one of the said electrodes for optionally applying and carrying a positive and negative potential to another of said electrodes.

EDMUND GUYER MURPHY.

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