US1551661A - Variable condenser - Google Patents

Description

Sept. 1, 1925. 1,551,661

C. G. HILL VARIABLE CONDENSER Filed May 20, 1922 Patented Sept. 1, 1925.

4 1,551,661 PATENT OFFICE.

CYRUS G. HILL, OF CHICAGO, ILLINOIS.

VARIABLE CONDENSER.

Application filed May 20, 1922. Serial No. 562,324.

To all whom it may concern:

Be it known that I, CYnUs G. HILL, a citizen of the United States, and a residentof Chicago, in the county of Cook and State of Illinois, have, invented certain new and useful Improvements in Variable Condenser-s, of which the following is a specification. V

This invention relates to variable condensers; it is the object of the invention to produce a variable condenser particularly useful in connection with radio work, simple and economical to produce and efficient in use. I

In the drawings, which present an illustrative embodiment of the invention,

Figure 1 is a sectional plan view of the device.

Figure 2 is a side elevation thereof.

Figure 3 is a plan view of the front of the device. i

The condenser, as a whole, is mounted between the discs 1 andQ, which may be of bakelite or other suitable material; it

may be mounted on the rear face of panel 3 (of a radio control box or the like) with the control knob 4: located in front of the panel for convenient manipulation.

Referring now to the operating parts of the condenser, I provide interleaved layers of conductive material and means for adjusting the average distance between the interleaved conductive strips, and I thereby adjustably vary the capacity of the condenser by adjusting the thickness of the layer of air dielectric between the conductive layers through j, convenient manual means.

To effect this resultI provide, in the embodiment of the invention here shown, a pair of spirals 5 and 6, formed of spring brass strips. (fine of these spirals 5 is attached to a terminal 7 (forming a post between the discs 1 and 2) and after a number of convolutions, its inner end is attached to the drum 8 by any suitable means, as by being sprung into a recess 9 and locked therein by a pin 10. The other spring brass strip 6, "attached at its outer end to the terminal and post 11 interleaves with the strip 5, and at its inner end is The other insulating strip 13 is in all respects similarly located with respect to the brass strip 6.

I have thus provided a multiple spring spiral comprising two conductors and an interposed insulating layer, the multiple spiral being resilient (somewhat after the fashion of a clockspring). It is obvious that if the multiple spiral is tightened the space between adjacent convolutions will be reduced, and vice versa -if it is loosened, with the result that the capacity of the condenser (comprising'the "conductive strips and the interposed air dielectric) maybe varied.

The drum 8 is rigidly mounted on a shaft 14 which has bearings in the discs 1 and 2. At the rear side the shaft 14 extends through the disc 1, is threaded and provided with a nut 15 adjustable by set screw This nut bears on washer 17 which forces the leather washer 18 against the face of disc 1. thus provided, holds the drum 8 against the tension of the multiple spring in any position to which it may be turned. The

shaft 14, at the front, extends forwardly a distance to clear the panel 3 and is there provided with the knob 4: suitably secured thereto.

Further details 'of construction may be described as follows: the two terminals 7 and 9 are recessed and threaded at their forward ends, and the disc 2 is attached thereto by screws 19, this construction being adapted at both ends of all the additional posts 20 which support and space the discs 1 and 2. The terminals and posts 7 and 9 at their rear ends are provided with shoulders 21 and extensions 22 passing through the disc 1 and threaded to receive the thumb nuts- 23 whereby wires may be attached thereto. A cylindrical casing 24 fits in grooves in the inner face of the discs and houses the condenser parts. The complete condenser may be secured to panel 3 by the screws 25 passing through the panel.

In operation, turning the knob 4 tightens or loosens the multiple spring spiral, there The adjustable friction,

by varying the average space between the conductor strips and thus varying the capacity of the condenser by varying the average thickness of the layer of air dielectric intervening between adjacent convolutions of the mutliple coil. The friction means, comprising the nut and associated posts, maintains the adjustment.

\Vhile I have shown herein a separate strip of non-conductive material, I may substitute therefor a strip attached to one or both faces of each, or both faces of one, strip 5 and 6, or I may coat one or both faces of each strip 5 and 6 (or both faces of one strip) with an elastic insulating varnish.

The invention, in its broader aspects, is not limited to the particular details here described and shown for illustrative purposes,

but is more properly defined in the appended claims:

L'A variable condenser comprising a plurality of spirally wound resilient conductors, a pair of terminals each in contact with half of said conductors, and rotatab'ly adjustable means for simultaneously varying the average distance between adjacent conductors.

2. A variable condenser comprising in combination a pair of terminals, a plurality of continuous layers of flat conductive material in electric-contact with each terminal, said layers being interleaved substantially in spiral form, and rotatably adjustable means for simultaneously varying the average distance between the adjacent layers.

3. A variable condenser comprising a resilient coil of conductive and dielectric material arranged in intervening layers, a layer of dielectric material being interposed between two layers ofconductive material, means for tightenin'gor loosening said coil to adjust the space between the layers of conductive material. 7' n 4.. A variable condenser comprising amultiple spiral formed of interleaved resil- 1ent conductive material, having its convolutions insulated from each other, and means for adjustably tightening or loosening the multiple spiral to vary the space between the convo-lutions thereof. v

5. A variable condenser comprising in combination a multiple spiral made up of two spirals of conductive material and an interleaved spiral of non-conductive mate rial and means for adjusting the average space between the convolutions of the spirals of conductive material by relative rotation of spaced portions of said spirals.

6. A variable condenser comprising a casing, a pair of terminals therein, a pair of spiral spring metal strips attached each to a terminal and interleaved with each other, a drum at the center of the spirals and attached to each thereof, a dielectric between the convolutions of said spring metal spirals and manual means for turning said drum to tighten or loosen the convolutions of said spiral strips.

7. A variable condenser comprising a casing, a pair of terminals'therein, a pair of spiral spring metal strips attached each to a terminal and interleaved with each other, a drum at the center of the spirals and attached to each thereof, insulating means betweenthe adjacent convolutions of said spring metal spirals and means for turning said drum and means for maintaining said drum in adjusted position.

8. variable condenser comprising a casing, a pair of terminals therein, a pair of spiral spring metal strips attached each to a terminal and interleaved with each other, a drum at the center of the spirals and attached to each thereof, dielectric between the adjacent convolutions of said spring metal spirals and manual means for turning said drum and means for maintaining said drum in adjusted position, in-

.cluding friction means for preventing the :rotation thereof.

In witness whereof, I hereunto 1 subscribe my name this 15th day of May, A. 1)., 1922.

CYRUS G. HILL.

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