US2466065A

US2466065A - Direct-current amplifier and circuit

Info

Publication number: US2466065A
Application number: US553178A
Authority: US
Inventors: Weichardt Heinz Hermann
Original assignee: Tung Sol Lamp Works Inc
Current assignee: Tung Sol Lamp Works Inc
Priority date: 1944-09-08
Filing date: 1944-09-08
Publication date: 1949-04-05
Anticipated expiration: 1966-04-05

Description

April 5, 1949. H. H. WEICHARDT 2,466,065

DIRECT CURRENT AMPLIFIER AND CIRCUIT Filed Sept. 8, 1944 g 4 I/ '0 2 g k F I I4 I I is L I I8 Oor+ a J V V L O Oor- W 1 +V+X +V F I G 2 INVENTOR. m-zmz HERMANN WELGHARDT J 1: BY Y Patented Apr. 5, 1949 U NiITI-JETD PATENT OFFICE v DIRECT-CURRENT AMPLIFIER AND CIRCUIT HeinzrHerma'nmWeicliardt, New York, N. Y.,, as-

:signorto: Tung-Sol Lamp- Works, Inc., Newark,

N.- .L, a corporation of Delaware Application-September 8, 1944, Serial No. 553,178

-1-6:Claims-.. (Cl. 315-15) invention relates to amplifier tubes and more. particularly to low voltage Dl C. amplifier tubes and circuits therefor; I

An object of the invention is-toprovidean amplifier of this type that' will be small, about the size of the conventional receivingtube, and will have a high amplificatiom factor;

Anotheriobiect ofthe invention is i to provide connected for amplification otvoltage variations:

of aphotocell. 7

Mynew amplifier i'sshown-at 2-0.

In Fig. 1, lrepresents diagrammatically any suitable evacuated envelope 'forthe elements of" the new amplifier; which elements include acathode- 2', preferably o'fthe indirectly heated type, an electronic lens I comprising slot'te'd' 'electrodes 4-" and" 6 and a meshelectrode 'B 'positioned therebetween, a control electrodel ng atarg'et' l2, a suppressor grid 1 "4 and an electrode I B' -adaptedto: be maintained 'at the potential of the electrode:

6. as by the connection l 8 therebetweem In use; mesh electrode is maintainedlatz-a potential substantially higher than that :"of'electrade 6. Thus if electrodest' and [6 are at potential V; electrode 8 will} be at: a pot'entialz of- V ta The potential 'of electrode: 4 may be equal to that of "th'e" cathode, or' it may be negative with respect thereto. The three where a: is positive;

electrodes together form: an electronic lens, the.

equi-potential 'iines'of which: :are: indicated in. the drawing. 'By formingthe-electrode: 8 ot'wire' mesh, the diverging effect of'an intermediately positioned slotted l'en's' "of" high potential.- ;is

avoided. The optical equival'ent'o'f. the threeielec trodeelectronic lens: is theiv two simple converging lenses symb'olically indicatedfiati lnrarrd:Lz in -the: drawing; The current 'absorbedkiby electrode'=:8=

wire'di'ameter to'=me'sh opening. :m'one' hundred.

mesh of .002" wire serves satisfactorily for the electrode 8. When the'potential of electrode'8 is about one and one-half: times that ofelectrode 6 the' electron beamma-y-be brought to a focus at ajpoint about 15mm. from the:=-lens.. Due

tothe relatively low potentials employed say from'200: to 500.'volts' on electrode 8, the'velocity of: the electrons leaving. the lens islet/enough. for deflection by the control electrode 10 duringv the short distance of travel of the beam-toward. the target I2.

As shownin. Fig. 1',, electrodes. l0- and. iii are elongated longitudinally ofthe tube-so. as to influence the electron beamthroughout its path.

Electrode l=0- preferably flares" outwardlytominimize the drawing of current by that electrode;

Target I2: is preferably maintained at the quiescentpotentialofelectrode it), which sub-1 stantially'that ofelectrodes l6 and 6'. The suppresscr 4 is T maintained: at the cathode potential Its: function is to prevent-the flow of secondary or slightly positive with respect thereto.

electrons from thetarget from reaching electrode l6 and. to shield-the target from electrode 5,

thereby preventing'the potentialdifference, set.

up during operation of the tube, from. reacting on the. deflection of the beam;-

During operation of the tubethe: positive voltages, the'variations of which are tobe amplified, are applied to electrode [0.

I0 is substantially equal to that of electrode Hi,

there is no. deflection of the beam of electrons and hence but a relatively small part of the beam falls on the target 12. Upon an increase ofpotential of electrode-ldthe beam is deflectedto. increase the flow of electrons to the target.

Consequently the targetpotential decreases in proportionv to the increase of potential on electrode l0. Upon decrease inpotential on electrode Hkthe beam is deflected toward electrode l 6 withccnsequentreduction in target-current and corresponding: increase of potential: thereof. The potential swing, of the target is substantially.

greater'lthan that of. the control electrode- -lll.

and hence the tube. operates as an. amplifier. With a tube of the size-of a-conventional-receiving tube an-amplification factor of IL=100' can be? easily obtained. The beam currentinzsuch At the quiescent. potential, that is, when the potential of electrode:

tube when the potential of electrode 6 is about two-thirds of electrode 8 is about 1 milliampere.

In Fig. 2 the new amplifier, indicated at 20, is shown with its control electrode [0, connected directly to the anode of a conventional threeelectrode amplifier 2|. Amplifier 2|, in the particular circuit illustrated in Fig. 2, is connected to amplify voltage variations of a photocell 22. A voltage divider 24 across the ends of which a constant potential difference of a few hundred volts is maintained, has a tap 26, near the positiveend, connected directly to the positive electrode of thephoto cell 22 and connected through a resistor 28 to the anode of amplifier 2|. The positive end of divider 24 is connected directly to electrode 8 of the lens of tube 20 andthrough a resistor 30 with the target l2. El'eca trodes l6 and 6 are connected through a lead 32 with an intermediate poin't'on divider 24. The

and electrode 4 of the lens in the specific embodiment of the invention illustrated is connected to the negative end of the divider. The control grid of amplifier 2| and thenegative electrode of the photo-cell are connected through a resistor 34 with a point on the divider of potential negative with respect to the cathodes.

The operation will be clear from the above description. Variations of voltage of the photocell 22 applied to the grid of amplifier 2| will appear as amplified variations in the positive potential of the anode of that tube. The varying positive potential of control electrode [0, being that of the anode of amplifier 2 I, will cause corresponding deflections of the beam of electrons issuing from the electronic lens with correspondin amplified voltage variations appearing on target I2. Hence amplified voltages will appear across

terminals

35 and 36, connected, respectively, with the cathodes of the tubes and with the target. These amplified voltagescould be applied directly across the control electrode and cathode of a succeeding tube if further amplification is desired.

The amplifier requires but relatively low operating voltages and the positive potentials, the var iations of which are to be amplified, can be applied directly to the control electrode or "grid without such electrode drawing substantial current. The small size of the amplifier is made possible by the provision of the electronic lens having only converging elements to which relatively low operating potentials are applied; the lens converging the electron stream from the cathode into a beam of short focal length with the electrons thereof moving relatively slowly so as to be readily influenced by changes in the control potential.

The new amplifier tube and circuit have now been described with reference to the drawings. It will be understood that various changes in the circuit or tube elements diagrammatically shown in the drawing could be made without departing from the spirit of the invention. For example, the electrode 8 of the electronic lens has been diagrammatically illustrated as being throughout of wire mesh. As the part of this electrode alined with the slots in electrodes 4 and 6 is the only part through which the electrons penetrate, it is not necessary that the entire electrode be of mesh. In practice the electrode 8 could, and preferably would, be made of a slotted metal sheet with wire mesh covering the slot.

The following is claimed: I

1. The low voltage direct current amplifier comprising a source of electrons, an electronic lens adapted to form the electrons from said source into a converging beam of short focus, a target adjacent the focal point of said beam and a control electrode positioned to deflect said beam upon changes of positive potential and flared outwardly therefrom.

2. In a low voltage direct current amplifier having a cathode, a control electrode and an anode target, a three-electrode electronic lens positioned between said cathode and said control electrode, said lens forming the electrons emitted by said cathode, into 'a converging beam of short focus.

3. The combination in'an amplifier tube of a cathode, control electrode, anode target and convergent electronic lens, said lens being positioned in the path of electrons emitted by the cathode andoperating to form a convergent beam of short focus and said control electrode being positioned 4. A low voltage direct current amplifier having a control electrode adapted to operate at positive potentials comprising in combination an evacuated envelope, a cathode, a 3-element convergent electronic lens, a, target and a diverging control electrode all within saidenvelope, said control electrode being positioned between said lens and said target and to one side of the convergent electron beam formed by the lens andsaid lens being so formedthat the optical equivalent thereof is a pair of simple convergent lenses.

5. An amplifier comprising in combination a cathode for emission of electrons, a slottedfirst electrode adjacent to said cathode and maintained at a potential not greater than that of the oathode, a second electrode maintained at a potential substantially Positive with respect tothe cathode, at least that part of said second electrode alined with the slot of said first electrode being of mesh, a slotted third electrode maintained at apotential positive with respect to the cathode and lower than that of said second electrode, said three cathode for emission of electrons, a slotted first electrode adjacent to said cathode and maintained at a potential not greater than that of the cathode, a second electrode maintained at a potential substantially positive with respect to the cathode, at least that part of said second electrode alined with the slot of i said first electrode being of mesh, a slotted third electrode maintained at a potential positive with respect to the cathode and lower than that of said second electrode, said three electrodes together comprising an electronic lens for forming the electrons emitted by said cathode into a convergent beam of short focus, a target positioned adjacent the focal point of. the electron beamand a con mete and an electrode positioned betweenthe lens and the target and:fonzitheppposite side of the beam fromsaid control electrode, said last mentioned electrode .being maintained'atfthe potenti'allof said third 'electrode". 7 p

7.? l amplifier "comprising ,i'in'." combination: a cathode. ;for emission 'ofel'ectrons; a slottedfirst electrode adjacent" to said" cathode and 'Tmain'; tainedilat a: potential .not'greate'r than? that :of theicathode';- a "second electrode "maintained fiat a potential "substantially"positive :With respect to the I cathodefatdeast that "part of said :se'cond electrode alined with the "slot of said first-elec' trode *being-.:"of *m'esh'; aslottedthird electrode maintained'at a potential positive with"respect to the cathode .and lower'ithan' that of said second electrode, said three electrodes together come prising an electronic lens forfforming theJelectrons emitted "by 'said'cathode into a convergent beam of short'ffocus-,1;a.target positioned adjacent the focal pointiof vtheelectron beam.and a control 'ele'ctr'ode positioned "between' the lens and the target and to one side of the electron beam" for deflection thereof toward and from the target and an electrode disposed on the opposite side of the beam from the control electrode and maintained at the potential of said third electrode and a suppressor maintained at substantially the cathode potential and positioned adjacent the target for shielding the target and suppressing the flow of secondary electrons therefrom.

8. An amplifier comprising in combination a cathode for emission of electrons, a slotted first electrode adjacent to said cathode and maintained at a potential not greater than that of the cathode, a second electrode maintained at a potential substantially positive with respect to the cathode, at least that part of said second electrode alined with the slot of said first electrode being of mesh, a slotted third electrode maintained at a potential positive with respect to the cathode and lower than that of said second electrode, said three electrodes together comprising an electronic lens for forming the electrons emitted by said cathode into a convergent beam of short focus, a target positioned adjacent the focal point of the electron beam and a control electrode positioned between the lens and the target and to one side of the electron beam for deflection thereof toward and from the target said control electrode being operated at potentials positive with respect to the cathode and being flared outwardly from the beam to minimiz the drawing of current.

9. An amplifying circuit, comprising two amplifier tubes, one of said tubes being a conventional tube having a control grid, an anode and a cathode and the other of said tubes being a low voltage direct current amplifier having a cathode, an electronic lens for forming electrons into a converging beam, a target and a control electrode positioned to deflect the beam formed by the lens, a connection between the cathodes of said tubes, a connection between the anode of said first tube and the control electrode of said second tube, and means for maintaining said anode and said target at potentials positive with respect to the oath-- odes whereby variations in potential applied to the control grid of the first tube appear at the anode thereof and at the control electrode of the second tube as amplified variations in positive po- 6* tennsranarappeae further amplifiefd at-ithe'targetii of said second tube-2;;

10. An amplifying circuit, comprising-ktwo am plifier tubes, one of said tubesi'beingqai convene-1 e tional tube having "a icontrolagrid; 'antanode and 2 a cathode and the other of said 'tubeszbeing a low" voltage di'rect current amplifier rh'aving 'a caths odegsan electronic lens forlformingtelectrons :into 3 I I a converging abe'am; a ltarget and fa lcontrolriele'c- 1dttrode positionedwto deflect lthebeamfo'rmed :by theile'ns, a connection *betweenifhe cathodes (of? said -tubes; a connectionilbetween the *anodecoff said first tube :and .the control electrodeieoffisaidcl second tube, and means for maintaining said-"an; mi; odean'd'said target at potentials-positive withxrespe'ctto the cathodes whereby variations-infpoten tia'li applied to' the contr'ol i'gridxiof :tlie .zfirst 'tube appear atwthefianode thereof iancl atrtheicontrol electrode -ofthe second ?tube: as. amplifiediivariae 203;; tion so in positive'apotentialz i and:- appear 1 further amplifiedl, atithe target "of said :fsecond tube; said; electronic lens comprising convergent '1 elements 1 only? 1 1. Am amplifying circuit comprising 1 two tame. plifien :tubs, one of 'said tubes: being acconviene tional-:tube having a control' 'grii anr'anode-and: a cathode' and 'the.-: other :of said ttubes beingsta-a low voltage direct current amplifier having a oath ode; an electronic lens forcforming electrons-1 into a converging 'zbea-msatar-get antla 's-controli :elece tlOdz'DOSi-tiblled 217C)? defie'ct 'the vbeam formed by the lens, a connection between the cathodes of said tubes, a connection between the anode of said first tube and the control electrode of said second tube, and means for maintaining said anode and said target at potentials positive with respect to the cathodes whereby variations in potential applied to the control grid of the first tube appear at the anode thereof and at the control electrode of the second tube as amplified variations in positive potential and appear further amplified at the target of said second tube, said means for maintaining the potentials of said anode and target positive with respect to said cathodes comprising a voltage divider having a connection adjacent its negative end to said cathodes, a resistor connected between said anode and a point adjacent the positive end of said divider, and a resistor connected between said target and the positive end of said divider and wherein said electronic lens comprises a first slotted electrode connected to the negative end of said divider, a second mesh electrode connected to the positive end of said divider and a third slotted electrode connected to an intermediate point on said divider.

12. A direct current amplifier comprising a cathode, a control electrode, a three element electronic lens for converging the electron beam from said cathode and a target anode all within an evacuated envelope substantially the size of a conventional receiving tube.

13. A direct current amplifier comprising a source of electrons, a three element electronic lens for forming the electrons from said source into a convergent beam said lens having a center element formed at least in part of wir mesh, a target adjacent the focal point of said beam and a control electrode positioned to deflect said beam upon changes of potential.

14. A direct current amplifier comprising a source of electrons, an electron lens adapted when potentials of the order of a few hundred volts are applied thereto to form the electrons from said source into a converging beam having a focal 7, length of the order of 15 mm., a target adjacent the focal point of said beam and a control electrode positioned to deflect said beam upon changes of positive potential.

15. An amplifier tube comprising a source of electrons, a three element electron lens converging the beam of electrons upon the application of a relatively low voltage thereto, a target adjacent the focal point of said converging beam, a control electrode positioned between the anode and the lens to deflect said beam upon changes of positive potential applied thereto, and a suppressor grid positioned between the control electrode and the anode.

16. An amplifier tube comprising a cathode for the generation of an electron beam, an electronic lens adjacent said cathode having at least three elements, the outer elements having slots therein and the middle element being formed of a wire mesh, said lens operating to converge the elecg0 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,075,142 Schlesinger Mar, 30, 1937 2,165,308 Skellett July 11, 1939 2,219,117 Schade Oct. 22, 1940 2,227,016 Schlesinger Dec. 31, 1940 2,255,485 Dome Sept. 9, 1941 2,265,311 Preisach et al. -1 Dec. 9, 1941 2,299,047 Winans Oct. 13, 1942 2,303,166 Laico Nov. 24, 1942 2,351,501 Gray June 13, 1944 2,358,902 Ziebolz Sept, 26, 1944 2,372,328 Labin Mar. 27, 1945 FOREIGN PATENTS Number Country Date 623,769 Germany Jan. 3, 1936 OTHER REFERENCES Myers, Electron Optics, Nostrand 00., N. Y. city, 1939, page 472.