US1641438A - Variable condenser - Google Patents

Description

Sept. 6,1927. L L JONES 1,641,438

VARIABLE coNDENsER A Filed Dec. 13, 1923 JJ f4 j v l INVENTOR F.j. 2b/V15: 1f Z3 BY L z/4 E ATTORNEYS Patented Sept. 6, 1927.

UNITED .STATES PATENTI OFFICE.

LESTER I.. JONES, or onADELL, NEW JERSEY.

VARIABLE CONDENSER.

Application led December 13, 1923. Serial No. 680,465.

This invention relates to a variable con` pending application 'for Capacitive coupling control system, Serial No. 607 ,046,

filed Dec. 15, 1922, the present application being a division and continuation 1n rpart of the said copending application.

The principal objects of my present invention include the provision of a variable compensating condenser designed for employment with relay or amplifier tube circuits in which the feed back of energy from the output to the input circuit due to the unavoidable capacitive coupling between the circuits is desired to be compensated or neutralized; the further rovision of a compensating condenser of t iis nature which vis made adjustable to adapt the same to different makes ory types of relay or amplifier tubes, and which is provided with means for preventing the detuning of the input circuit during condenser adjustment; the still further provision of a condenser of this nature in which the elements that are adapted for connection to high potential points of the receiving circuit are electrostatically shielded, and in which furthermore the parts are so inter-related that in spite of the very low capacity values of the condenser .(of the order of 10 1n. In. f.,s) adjustment is unvaffected by the hands or body of the operator `or user in obtaining a setting 0f the same.

To the accomplishment, of /the foregoing and such other objects as may hereinafter appear, my invention consists in the'elements and their relation one to the other, ashereinafter particularly described and sought to be defined in the claims, reference b eing had to the accompanying drawings which show' preferred embodimentsA of my invention, and in which Fig. 1 is aview taken in cross-section of one form of my compensator condenser,

Fig. 2 is a cross-'sectional view -of a modification thereof.

Fig. 3 is a view taken in cross-section on the line 3-3, Fig. 2,

Fig. 4 is `a perspective view showing the parts detached and the manner of 'assembling the same, and.

l Fig: 5 is a diagram of a relay or amplifylng c1rcu1t showing my invention applied thereto.

Referring first to Fig. 5 of the drawings,

I show7V an amplifier or relay tube circuit system for exemplifying a contemplated mode of application or use of my invention.

The relay tube system comprises an electron i discharge or thermionic relay including the Ii'ament 10 which is heated to incandescence by the battery 11 connected thereto for producing the electron stream, the controlling grid 12 and the controlled plate 13,.the grid being connected to a controlling` or input circuit i and the plate being connected to a controlled or output circuit o. i

The input circuit is provided as usual with an inductor 14 which may be coupled for energy reception to an induction coil of an antennae circuit and a variable condenser.15 connected in parallel tothe inductor 14, the condenser being adjustable,fas is well known, for varying the tuning characteristics or period of the input circuit to syntonize the same to the desired incoming frequency,

`the said inductor and condenser being connected to the grid or high potential side of the input circuit and to the lament by means of the conductors 16 and 17 respectively. v

The output circuit o is provided with an external or output impedance 18 connectedy at one end by means of a conductor 19 to the plate 13 and connected at the other end by means ofthe conductor 20 to the positive terminal of the battery 21, the negative terminal of which is connected to vthe filament 10, as clearly shown in the drawings. The output inipedance 18 may as shown comprise the primary of a transformer `and is coupled to a secondary (not shown), the said secondary receiving the amplified energy for rectification or further amplification if desired. 4 l

As explained in the above mentioned parent application, due to the normal Unshield- `able capacity between the plate 13 and the grid 12 of the electron discharge tube, some of the energy in the output circuit is objectionably retransferredy or fedback to the input circuit, the grid 12 being charged byv the plate 13 through the capacity therebetween. For compensating for this feed back to 'reduce or entlrely leliminate the effect of the same, I provide means for neutralizing in part -or in whole the charge carried from sof . put circuit simultaneously" the plate to the grid. This result I accomplish by providing means for impressing on the grid 12 a charge which may be less than, equal to, or greater than in magnitude but opposite in sign to the charge carried thereto from the plate; and to this end Iprovide means for creatingI a potential .opposite'to the otential on the plate and impressing the sai potential on a capacity means connected to the grid 12. Where feed back is desired to be entirely eliminated, the product ofthe said potential and the capacity is made equal to the charge transferred to the grid from the output circuit.

. For creating the opposite potential, I p rovide an additional impedance 23 comprising a coil wound in the same direction as the output impedance coil 18 closely cou led to the same and lhaving a number o turns preferably equal to the number of turns in the winding 18, the said additional impedance being connected at one end to the conductor y20 and at its other end by means of a conductor 24 to a condenser 25 which is connected as shown to the high potential side of the input circuit by means o a conductor 26, the said condenser being preferably made equal to the capacity between the grid and the plate and the capacity between the 'conductors or leads connected thereto (of the order of 6 m. m. f.s for present-day receiving tubes). By creating a potential opposite in sign to the potential on the plate 13 and by impressing the same on the condenser 25, it will be apparent that vthe grid 12 is supplied with an electric charge which is equal and opposite to the charge fed back thereto from the plate 13,'this equalization or neutralization of the charge preventing the setting up of objectionable local oscillations in the input circuit.

For the purpose of ad'usting the compensating e ect to adapt t e saine to different relay tubes, the internal capacities of which vary, and to the capacity of the leads which may vary in dilerent receiving sets, the condenser 25 is made variable; and to this end includes a movable plate or ele ment a and a stator plate or element c, the ormer being movable with respect to the latter in opposite directions, as indicated by the arrows in'Fig. 5.y

-In vievy7 of the ne ligible impedance of the coil 23 as compare with the impedance of the grid coil 14, the chan e of capacity be# tween theplates a and c urin adjustment is normally effective for modigying the capacity of the grid circuit and hence the period of the same. For the purpose' of preventing this variation of capacity of the condenser from varying the tuning characteristics or period vof t e cuit, I have found it desirable to provide means for varying the capacity of the inand inversely in id or input cir-v correspondence with the varying of the capacity of the equalizing circuit. To this end the condenser 25 includes a third and stator plate or element b connected to the filament side of the input circuit by means of a 'conductor 27, said filament side of the circuit being preferably grounded as shown yfor varying the capacity of one plate set inversely with respect to the other plate set. By the provision of this construction it will be seen that the effective grid circuit capacity may be maintained constant dur ing adJustment of the condenser plate a so that the tuning oi' period of the grid or input circuit is maintained.

The three-plate condenser of my invention may constructionally take the form shown in Fig. 1 of the drawings, in which the three plates comprise cylinders or tubes a', b and c', the tubes b and c being fixed or stationary and forming the stator element and the tube a being telescopically movable in opposite directions between the tubes .b and c and formng the movable element. The tube a is provided with a connecting means 29 for connection to the high potential side of the grid circuit, the tube b is provided with a connecting means 30 for connect-ion to the filament and ground end of the circuit, and the filament c is similarly provided with a connecting means 31 for connection to the impedance of the equalizing circuit. The tube b may be ixedly carried by a collar 32, the said collar being threadedly received by a threaded bushing 33 which is stationarily mounted on a panel board 34, the panel board being secured between the shoulder 35 of the bushing 33 and the collar 32. Fitting within the tube b', I provide 'a tube of insulating material 36 such as hard rubber on which the tube c is fixed by means of the connecting element 3l, the tube a being constructed to telescopically slide .in the tube of insulating material.

For `moving the plate element a', there is providedethe shaft or spindle'37 made of electrically conductive material which is threaded the greater part of its length as shown at 38 for threaded engagement with a tapped member 39 ilixedly carried by an insulating dial member 40 which carries a plate sets ac and ab, moveics pointer 41. The shaft is longitudinally recessed as at 42 for receiving a pin 43 fitted and the complemental stop pin 4T car' tached to the shaft 37 as by, being threadedy thereto, as shown in the drawings. For

shielding the high potential elements of the condenser from the hand of the operator, the shaft 37 is conductively connected to the stator plate b which is to be connected to ground, the conductive connection being provided by making the parts 32, 33, 35 and 39 ot' electrically conductive material. With Vthis arrangement the plate b provides a ground shield for the condenser elements Referring now to Figs. 2 to 4 of the drawings, I show a modification of my compensator condenser in which the adjustment from maximum capacity of one plate set to maximum capacity of another plate set is obtained through a half-revolution of the operating shaft. In this construction the movable element a2 is carried b an insulating body or plate 44 ixed tot e metallic shaft 37 and the stator elements b2 and c2 are fixedly attached to 'an insulating plate'or body 45, they said plate a2 being provided with the connecting means 29 and the plates b2 and 02 being provided respectively with the connecting means 30 and 31', a sheet of dielectric material 36 being arranged between the stator and movable plates. For limiting the movement of the rotor plate with respect to the stator plate, I provide the two stop pins 46 carried by the insulating body ried by the insulating body 44', the sheet of dielectric material 36 being provided with a slot 48 through which the in 47 projects, as clearly shown in Fig. 2 oi'the drawings.

For shielding the high potential .elements of the condenser inthe form of construction shown in Figs.' 2 to 4 of the drawings and for connecting the shaft 37 to ground, I

" provide a separate electrostatic shield 48 which forms a carrier for the parts of the condenser, the said shield being connected `to the ground plate b2 'by means of the securing element 49, the shield plate 48 being cut or stamped out of sheet metal in a manner to provide the spring fingers 49', 49', the lower endsof which surround and engage theshaft 37',- as clearly shown in Fig. 3 of the drawing. By means of this construction it will be evident that when the plate b2 is grounded, the shaft 37 .and the shield plate 48 are both at ground, otential.

In mounting this compensator con enser on a support or panel 34', the dial 40 is secured to the shaft 37 and aspring washer 50 is inserted between the panel and the dial to hold the condenser plates in properly spaced relation.

The manner of constructing and using my compensatorcondenser will in the main be apparent from the above detailed description thereof and the mode of application of the same. It will be further apparent that while I have shown ythe compensator condenser in the preferred forms, that numerous changes may be made therein without departing from the spirit or principle of the invention. It will be obvious, for example,

that while I prefer to provide a single con-v denser element in the rotor common to both condenser plate sets, that this may be varied in many ways to accomplish the same. result. It will be also obvious that the parts'may be re-arran ed without departing. from the essence of t e invention defined in the following claims.

I claim: v

1. A variable condenser comprising a plurality of plate sets including two independent stator elements, a movable element capacitively related to both stator velements and a shaft insulatably carrying the movable element and conductively connectedA to one of said stator elements.

2. A variable condensercomprising a plurality of plate sets including two stators and a rotor common to the stators, rotation of the rotor being effective for varying the capacity of one plate set inversely with respect to the other, and a shaft made of an electrically conductive material insulatably carrying the rotor and conductively connected to one of the stators.

3. A variable condenser comprising a plurality of plate sets including relatively movable elements, and means for moving the movable element to vary the capacit of one plate set inversely with respect to the other plate set, said means including van electrically conducting shaft insulatably carrying the movable element and conductively connected to astationary element.

4. A variable'oondenser comprising a plu- 'rality of' plate sets including two stator plates and avrotor plate arranged so that when rotated throug capacity betweenthe plates will be varied a half revolution the lill' lli from maximum ca pacity of one plate set to i maximum capacity of another plate set, and a shaft insulatably carryingthe rotor element and conductively connected to one of -4 the stator elements.

5. A ,variable condenser rcomprising a plurality of plate sets including relatively movable elements, a shaft insulatably Carrying the movable element, and an electrostatic shield conductively connected to said shaft land to a stationary element.

62A variable" condenser vcomprising a plurality of plate sets including two stator elements, a movable element, a shaft made of an, electrically conductive material insulatvably carrying the movable element and an rality of plate sets including two stator elements, a movable element, a shaft made 'of an electrically conductive material insulatably carrying the movable element and an electrostatic shield conductively connected to said shaft and t0 one of said stator elements. 8. A variable condenser comprising a plu rality of plate sets including relatively movable elements, a shaft insulatably carrying the movable element, and an electrostatic shield conduetively connected to said shaft.

9. A variable condenser comprising a pair of independent stator plates, a rotor plate common to the stator plates, a conducting shaft insulatably tarrying the rotor plate and a stationary electrostatic shield conductively connected to the shaft.

10. A variable condenser lcomprising a pair of independent stator plates, a rotor plate common to the stator plates, a conucting shaft insulatably carrying the rotor plate and a stationar electrostatic shield conductively connecte to the shaft and to one of said stator plates.`

11. A variable condenser comprising a plurality of plate sets including relatively movable elements and means for operating the elements to vary the capacity of one plate set inversely with respect to the other plate set, and an electrostatic shield conductively connected to a stationary element of said plate sets.

Signed at New York New York and State of day of December, A. D. 1923.

LESTER L. JONES.

iNty in the county of ew York, this 8th

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