US1703574A

US1703574A - Variable condenser

Info

Publication number: US1703574A
Application number: US154368A
Authority: US
Inventors: Ernest G Danielson
Original assignee: Individual
Current assignee: Individual
Priority date: 1926-12-13
Filing date: 1926-12-13
Publication date: 1929-02-26
Anticipated expiration: 1946-02-26

Description

Feb. 26, 1929.

E. a. DANIELSON VARIABLE connsnssn' Filed Dec. 13, 1926 ting/60001250? 7 MW Patented Feb. 26, 1929.

UNITED, STATES ZIJBINES 'J. G. DANIELSON, OF SAN FRANCISCO, CALIFORNIA.

VARIABLE ooimnnsnn.

Application filed December 18, 1826. Serial 1T0. 154,368.

This invention relates generally to devices for tuning electrical circuits.

In radio apparatus where close tuning of electrical circuits is essential, it has become common practice to utilize two manual controls for a variable tuning condenser or other tuning unit, one control being for coarse approximate adjustment, and the other being for fine vernier Variations. The vernier control however, is associated yvith the condenser so that it effects a given movement of the electrodes for a given movement of control regardless of the setting of the condenser. Thus when a condenser is used with a resonant circuit having agiven inductance, the frequency variation effected by movement of the vernier when the condenser is near maximum capacitance will be slight compared to the frequency variation effected by like movement when the condenser is near minimum capacitance. For this reason, the vernier adjustment is not sufiiciently fine for short wave lengths and is hardly noticeable for the long wave lengths. 1

It is an object of this invention to devise a Vernier control for a variable condenser or other tuning unit which will be equally effective at all settings of the condenser.

It is a further object of this invention to devise a vernier control for a variable condenser which will not only be effective at all wave lengths, but will have a straight line frequency characteristic.

It is another object of this invention to devise a vernier control for a variable condenser comprising a motion transmitting mechanism adapted to automatically change its mechanical advantage for diflerent settings of the condenser.

It is a further object of this invention to devise a novel form of gang control for variable condensers which will incorporate a vernier adjustment.

Further objects of this invention will appear from the following description in which I haveset forth the preferred embodiment of my invention. It is tobe under-- stood that the invention is to be accorded a range of mechanical and electrical equivalents consistent with the state of the prior art.

Referring to the drawings:

Figure lis a side elevational view of a gang control condenser incorporating the principles of this invention, the electrodes of two of the condensers being removed to show the operating mechanism.

Fig. 2 is a diagrammatic illustration showing the operation of thevernier control.

Fig. 3 is a cross sectional detail view taken along the line 33 of Fig. 1. I

Fig. 4-is a top plan'view showing a portion of one of the condensers.

The invention comprises generally a special form of vernier. control which may be incorporated with any of the common types of variable condensers or variable tuning units. This vernier control consists generally of a manual control member connected to a condenser electrode or tuning element by means of a motion transmitting mechanism which is adapted to automatically change its mechanical advantage for different settings of the condenser. Thus when the condenser is set near its minimum capacitance a given increment of movementof the vernier control will effect comparatively slight relative movement between the condenser electrodes, while when the condenser is set for a greater capacitance, say

near its maximum value, the same incrementof movement of the vernier control member will effect a much greater relative movement between the electrodes. By employing a cam as a part of the motion transmittingmechanism the vernler may be given a Thus referring to the drawings, there has I been shown a plurality of variable condensers numbered 11, 12 and 13 which are adapted to tune separate circuits of a radio receiving apparatus. For example, condenser 11 may be employed to tune the antenna circuit of a radio receiver while condensers 12 and 13 may tune the first and second stages of a radio frequency amplifier. For purposes of illustration the invention has been shown as incorporating variable condensers of the type disclosed and claimed in my copending application, Serial No. 111,193, filed May 24, 1926, and entitled Variable condenser, although it is obvious that any form of tuning unit may be employed, whether inductive or capacitative. Such a condenser comprises a pair of relatively movable electrodes 14.- and 15, each ,bore 24'. Fullcontrol of the electrodes from maximum to minimum positions is secured by suitable control mechanism including in this mstance a manually rotatable shaft 18, to which is secured the cam 19. The electrodes 14 and 15 are adapted to move oppositely by suitable means such as the, intermeshing gears.

20, which are fixed with respect to the electrodes 14 and 15 respectively. Motion is transmitted-from the cam 19 tothe electrodes by means of a lever 22 pivotally se- 25 engaging in the s iralcam groove 26. It is preferable to provide a connection between the arm 22 and one of the gears 20 which will permit an adjustment of the minimum capacitance of each of the condensers. Suchan arrangement is shown in my copending application to which reference has previously been made, and comprises a member 30 adjust-ably secured to one of the gears 20 and carrying a pin 28 slidably disposed in the slot 27 of lever 22. Member 30 is provided with a slot.,32 through which extends a screw or bolt 33 for clamping the member to the gear face. A pin 34 secured to the gear face also extends into slot 32 to guide the member 30. When the electrodes are in their position of maximum. capacitance the lever 22 will be in the position shown with respect to condenser 12. The slot 27 is disposed in alinement with the pivotal connection 23 and pin 28 while the member 30 is guided in such a manner that with the condenser in this maximum position it will slide parallel to slot 27. However, when the condenser is in its minimum position, movement of member 30 will not be parallel to ,slot 27, with the result that when the position of this member is adjusted, it will effect an adjustment of the minimum capacitance of the condenser without affecting the maximum capacitance.

i 'In practice the condensers are mounted in spaced relationship upon a suitable panel 36 which may form a part of a radio cabinet or which may be positioned behind an instrument panel 35. If the panel 36 is of insulating material the working parts of the condensers may be mounted directly thereto but if a metal panel is employed, such as shown, the condenser parts are preferably mounted u on the individual insulating bases 24 whlch are then secured to the panel 36 by suitable means such as screws 37 The control shaft 18 is rotated by any convenient device which is graduated to indicate the settings of the electrodes. In the drawings there Is shown a graduated dial 38 directl mounted upon the rotatable shaft 18, a though of course it is to be understood that such a dial or other indicatin device may be mounted u on another rotata le shaft geared to the sha t 18. The cam groove 26 is preferably cut in such a manner as to impart to the condenser a straight line frequency characteristic when used with a given inductance, that is, so that angular movement of the control shaft 18 will have a linear relation to the frequency of the circuit being timed;

I In order to secure simultaneous or gang control ofthe condensers the levers 22 are connected to a common traversing member or bar 39. In case of condenser 11,'since it is usually unnecessary to have vermer movecured to the condenser support 24 as by rment for one of the condensers of a gang conmeans of pivot pin 23, and carrying a pin trol tuning device, the traversing bar 39 maybe directly connected thereto as by means of pivot pin 40 engaging in extension 41 of lever 22. However, in case of the condensers 12 and 13 the connection between the traversin member 39 and lever 22 includes a part 0 a vernier mechanism. Thus between bar 39 and the extension 41 there is connected a link 42 having a pivotal connection 43 with extension '41 and a pivotal connection 44 with bar 39. In order to secure vernier movement of the lever 22 and therefore of the electrodes, the link 42 is adapted to be moved angularly with respect to the traversing member 39 by mechanism which preferably includes an arm 45 fixed with respect to the link 42, the arm 45 engaging an actuating lever 46 pivotally mounted as at 47 One portion 50 of the actuating lever 46 is adapted to-be moved by rotation of a vernier control shaft 48 which has been shown as provided with a cam 49 engaging a pin 51 fixed to the actuator lever 46. The other portion 52 of this actuator is provided with a slot 53 within which extends a pin 54 fixed to the arm 45. The actuator lever .46

is preferably biased in a direction to maintain the pin 51 in contact with the cam 49, and for this purpose there has been shown a biasing spring 55 having its one end secured to panel 36 and its other end secured to the actuator. 4

The operation of the vernier control may that the traversing member 39 is any member movable for the purpose. of setting the electrodes at any position between maximum and minimum capacitance. If the link 42 remains relatively stationary with respect than when they are set near their-minimum to the traversing member 39, movement of this member will be directly transmitted to the lever 22 and the locus of the center of pin 54 will be substantially the same as the locus of a point upon the traversing member 39. With the levers 22 pivoted as at 28, the traversing bar 39 must necessarily move in a curved path and therefore the locus of pin 54 will be a similar curve. The slot 53 is cut in portion 52 in such a manner as to coincide with this locus of pin 54 so that when the actuator lever 46 remains stationary, movements of the traversing member 39 will be transmitted directly to the, condenser electrodes and link 52 will remain relatively stationary with respect to bar 39. However,

when it is desired to efl'ectvernier movement of the electrodes while the traversing member 39 remains fixed at a given setting, the Vernier control shaft 48 is rotated as by means of a knob 56, and this rotational movement by virtue of cam 49 causes rocking of the lever 46. This movement of lever 46 moves arm 45 and therefore link 42 angularly with respect to traversing member 39, with the result that movement is imparted to lever 22 independently of the traversing member 39. The mechanical advantage of the motion transmitting mechanism connecting the control shaft 48 with the condenser electrodes depends directly upon the distance between the centers ofpivot 47 and pin 54, this distance being indicated in the drawing by letter a. However, when the electrodes are moved to their position of maximum capacitance as by moving the traversing member 39 to the left to the limit of its movement, the distance between the pivot 47 and the pin 54 will have changed to the distance 5. Likewise when the condenser is moved to its minimum capacitance position the distance between centers of pivot 47 and pin 54 will decrease to the value 0. Therefore it is obvious that the mechanical advantage of the motive transmitting mechanism for the Vernier control .varies for different settings of the condenser electrodes and that it decreases when the capacitance of the condenser is decreased by movement of the traversing member 39.

V For a given increment of movement of the shaft 48 a much greater movement will be imparted to the electrodes when they are set near their maximum capacitance value,

value. The change in the mechanical ad-. vantage is preferably made such that for any setting of the condenser the vernier may be made to tune the condenser over a certain; frequency difference. By proper proper-f tioning the curvature of cam 49 this fre quency variation of the Vernier control is also preferably given a straight; line fre quency characteristic. operating the Vernier with a gang control condenser such as shown it is obvious that movement of the dial 38 will effect simultaneous control of all of the condensers while individual control of shaft 48 will effect a Vernier control of either condenser 12 or 13. If it is desired to secure automatic compensating movement of the electrodes of condensers 12 and 13 the actuator lever 46, shaft 48 and cam 49 may be omitted and a cam fixed to the panel 35 having a cam surface engaging the pin 54. By proper proportioning this cam surface the arm 45 and link 42 may be given sufficient movement to automatically maintain the circuits connected to condensers 12 and 13 in resonance relatively movable electrical elements, control means for effecting relative movement of said electrical elements between maximum and minimum positions, and means for effecting Vernier movements of the electrical elements comprising a control member, and mechanism interconnecting said member and one of said electrical elements for effecting a lesser relative Vernier movement of the electrical elements for a given increment of movement of the Vernier control member for settings of small value, than for settings of greater value.

2. A variable tuning device comprising relatively movable electrical elements, control means for effecting relative movement of said electrodes between positions of maximum and minimum tuning value, and means for effecting a Vernier movement of the elements for any setting of the elements, said means including a control member, motion transmitting mechanism interconnecting said member with one element, and means for. automatically changing the mechanical advantage of said mechanism for different settings of the elements.

3. A variable tuning device comprising relatively movable electrical elements, control means for effecting relative movement of the elements between positions of maximum and minimum tuning value, and means for effecting a Vernier movement of the elements comprising a rotatable control member, and motion transmitting mechanism inmentsbetwcen positions of maximumand:

minimum tuning value, and means a for effecting a vernier movement of the elements comprising-a rotatable control member, and

means operatively connecting said member and an element, including a motion transmitting lever, and means for automatically varying the effective leverage ratio of said lever for different settings of the first named control means. I

5. A variable tuning device comprising relatively I movable electrical elements, a traversing member for setting said elements at positions between "maximum and minimum tuning positions," motion transmitting means interconnecting the traversing member and .an element, and means associated with saidmechanism for effecting vernier control oftlie elements.

'6. A variable tuning device comprising relatively movable electrical elements, a traversing control member, motion transmitting means connecting said traversing member and an element whereby said elements may beset at any position between maximum and minimum. tuning positions, said means including a lever movable to effect vernier movement of the elements, and

a vernier control member for actuating said lever. p

7. A variable tuning device comprising relatively .movable electrical elements, a traversing control member, motion transmitting means connecting said traversing member and an element whereby said elements may be seti-at any position between 7 maximum and minimum tuning positions, said means including a lever movable to efiect vernier movement of the elements, a vernier control member for actuating said lever, and means for varying the amount of motion imparted to said-lever for a given increment of movement of the control member for difierent settings of the elements.

f8. A variable tuning device comprising relatively movable electrical elements, a traversmg control member, mechanism connectingsaid traversing member and an element for varying the tuning value of the device between wide limits, said mechanism including as an element thereof an arm'mov able to' effect a vernier adjustment of the elements,'said arm-being adapted to be bodily shifted upon movement of said traversing moans member, vernier control means adapted to move said arm to effect vernier adjustment ot the elements, said vernier control means having a point of application upon the arm relatively movablethereto upon movement of the traversing control member.

9. A variable tunlng device comprlslng a pair of relatively movable electrical elements, control means for effecting relative vmovement of said elements between positions of maximum and minimum tuning value, and meansfor effecting vernier movement of said electrodes, said.last named means including a manual control member, a lever adapted to be oscillated by said member to effect relative 'movementbetween the elements, and means for automatically varying the movement of the lever for a given increment of movement of the control member for different settings of said first named control means.

10. A tuning device comprising a plurality of variable tuning units secured to a common support, a gang control for said units including a traversing member, alinkage connection between said member and one of the units movable to secure vernier control of the same, and'independent control means for actuating said linkage connection.

7 11. A tuning device comprising a plurality of variable tuning units secured toa common support, a gang. control for said units including a traversing member, a linkage connection between said member and one of the units movable to secure vernier control of the same, an arm fixed'to said member and independent control means for actuati'ng said arm.

12. A tuning device comprising a plu'; rality of variable tuning units secured to a common support, a gang control for said units including a traversing member, a linkage connection between said member and one of the units, said connectionbeing shifted bodily upon movement of the traversin member and being movable angularly't ct: fect'vernier adjustment of .saidunit, an arm fixed to said connection, and vernier control means for actuating said arm, said arm being movable relative to the point of appli-' ber.

' Intestimony whereof, I have hereunto set my hand.

ERNEST G. DANIELSON.