US1804243A

US1804243A - Current regulating device

Info

Publication number: US1804243A
Application number: US294251A
Authority: US
Inventors: William L Bond
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1928-07-20
Filing date: 1928-07-20
Publication date: 1931-05-05
Anticipated expiration: 1948-05-05

Description

May 5, 1931. w. L. BOND 1,804,243

CURRENT REGULATING DEVICE Filed July 20, 1928 InvenTor' William L. Bond,

Hi5 ATTOr'ne Patented May 5, 1931 UNITED STATES PATENT OFFICE wnmnn I. BOND, OI SCHINECTADY, YORK, ASSIGNOB TO GENERAL ELECTRIC OOHPANY, A CORPORATION OF NEW YORK CURRENT nmum'rme DEVICE Application am Jul so,

My invention relates to current regulating devices, more particularly to variable resistance devices such as rheostats and potentiometers, and has for its object the provislon of a current regulating device having a varyingresistance per linear unlt whereby a tapered or non-uniform current control may be obtained.

My invention has particular application to rheostats and otentiometers such as are used in radio receivers wherein the resistance element or conductor is in an annular form and the resistance is increased or decreased by means of an angularly movable contact arm.

In general, the sound output from a radio receiver is controlled by means of a variable resistance in some part of the circuit, and the well-known wire wound rheostat is often employed. A disadvantage of the-ordinary wire wound rheostat is that such a rheostat does not allow a control of sound volume which is uniform throughout the range of the rheostat. This is due to the fact that the resistance of the rheostat is ordinarily a linear to function of the angle of movement of the contact arm, whereas the sound output is not always a linear function of the resistance. It is therefore desirable to use a rheostat, the

resistance variation of which is other than a linear function of the movement of the contact arm so that the variation in sound volume may be substantially proportional to the movement of the contact arm.

In carrying out In invention I have provided a current regu ating device utilizing a pluralit of resistance elements having different egrees of resistance per linear unit, the resistance elements being held in overlapping, parallel, electrically contacting relation.

For a more complete understanding of my invention reference may be had to the accompanying drawing in which Fig. l is a rear elevation of a rheostat embodying my invention; Fig. 2 is a side elevation in section taken along the lines 22 of Fig. 1 looking in the direction of the arrows, and Fig. 3 is a perspective view showing the parts of the rheostat in detached, unassembled relation.

Referring to the drawing, in carrying out me. Serial 1%. 294,251,

my invention in one form I have provided a rheostat comprising a base member 10, on which is secured a high resistance element or conductor 11, having a substantially constant resistance per linear unit, and a low resistance element or conductor 12 in overlapping, contacting relation with a portion of the high resistance element for varying the effective resistance per linear unit thereof. It is preferred that the base member 10 be made of porcelain although any other suitable insulating material may be used. An operating sha t 13 passes through the base member 10 at approximately the center thereof, and to one end of the shaft 13 is attached a movable contact arm 14.

Contact terminals

15, 16 and 17 are provided, being connected respectively to the ends of the high resistance element 11 and to the contact arm 14. The base member 10 is preferably formed in one piece and is provided with apertures 18 through which suitable bolts, not shown, may pass in order to secure the rheostat to a panel or instrument board.

The operating shaft 13 passes through and is rotatably mounted in a headed metallic bushing 19, held in place in an aperture 20 by a nut 21. The shaft 13 is prevented from longitudinal movement through the bushing 19 by a split ring 22 in engagement with the bushing. One end of the shaft 13 contains a central indentation and a transverse slot 23. As shown more clearly in Fig. 3, an aperture 24 in the contact arm 14 is of a size and shape such that the contact arm may be pushed over the end of the shaft 13 co-operating with the slot 23 and after assembling, the end of the shaft 13 is peened over, thus holding the contact arm 14 securely to the end of the operating shaft. The contact arm 14 has integral therewith small projections 25 and by the engaging of these projections with the enlarged end of the terminal 17, as shown in Fig. 2, an efficient wiping contact is obtained. The terminal 17 is secured to the base by means of a rivet 26.

The base member 10 is substantially circular in form but contains an indentation or groove 28 of predetermined length in its periphery extending, as shown, around apold thelow resistance element 12.

The high resistance element 11. comprises an insulating stri or core 29' about which is wound a high resistance conductor30. The high resistance element is of substantially circular sha e and of a width slightly greater than the wi th ofthe periphery of the base ll). The low resistance element 12 comprises an insulating strip 31 about which is wound a low. resistance conductor 32. The

strips

29 and 31 are preferably made of a phe olic condensation product or some other suit le insulating-material. While I have shown the low resistance conductor 32 as being made of a wire larger than'the wire forming the high resistance winding 30, I do'not wishto be limited to this particular arrangement since the resistancelelement may take other forms. For-instance, theresist'ance element 12 might be wound with the same size or even smaller wire than the resistance element 11 depending on the efiective resistance desired. The high resistance element 11 may be wound eitherwith bare wire or withinsulated wire. If insulated wire is used, the inside and the exposed edge of the element 11' should be cleaned of the insulation. The low resistance element 12 is preferably wound with bare wire.

The metallic terminals 15 and 16 are .L-' shaped and one end of each terminal is cutas shown in Fig. 3, forming two projections 33 and 34, The projection. 33 contains a small hole into which the end of the high resistance conductor 30. is placed and preferably soldered. Stop members 36 integral with the terminal 17 act t'o'stop or limit the angular movement of the contact arm 14. One end of the terminal 17 is enlarged and contains an a erture 37 through which the shaft 13 passes,

t e enlar ed end of the terminal serving as a hearing or the projections 25 on the contact arm as described hereinbefore. The outer ends ofthe

terminals

15, 16 and 17 are cut and bent as shown in Fig. 3 to facilitate the solderin thereto of external connections.

In or er to secure the various parts of my device in position a metallic clamping member 38, substantially circular in she and containing

extensions

39 and 40, 1s provided.

The extensions39 and 40 contain apertures.

through which a bolt 41 is placed and by screwlng this bolt into a nut 42 the member 38 is clamped securely around the high resistance. element 11, thus holding the low resistance element 12 in the groove 28 between the high resistance element 11 and the base 10. A flexible insulating strip 43 of approximately the same width as the clamping memher 38 is adapted to be placed between the clamping member 38 and the high resistance element 11.

In assembling the parts of my rheostat the resistance element 11 is placed around the eri hery of'the base member thus holding the ow resistance element 12 inplace. The termmals 15 and 16 will be clamped between the high resistance element -11 and the base- 10in grooves 44 in the base 10 provided for them. The insulatin strip 43- 'and clamping member 38 are then p aced around the outside of the hi h resistance element 11 and by means of t 6 bolt 41 the resistance elements 11 and 12 and the'terminals 15 and 16 are thus securel clampedin place. The projections 33 an 34 at the ends of the terminals 15 and 16 are then. bent upwardl at right an-' gles against the right-hand sur ace of the base I 10 as viewed in Fig. 2.

It will be observed that the winding32 of the low resistance element 12 is held,

throughout the, length of the low resistance element, in parallel, electrically contacting relation with the inside of a proximately onethird of .the winding 30 orming the high resistance element 11, the bare surfaces of the two windings being pressed against each other due to theclampmg action of the ring.

38. The-groove 28.is of a width such that, when the resistance elements are in position, the outer edge of element 12'will be spaced inwardly cm the contact-making edge of the element 11, that is, the low re 4 sistance element 12 will not be engaged by the contact arm 14 as this arm moves over and in contact with the high resistance element 11.-

Assuming that the contact arm 14 is moved from starting position at a. uniform rate in a counter-clockwise direction, as viewing Fig. 1, the effective resistance between terminal 16 and terminal 17 will increase uniformly at a certain rate until the end of the contact arm passes the point at which the upper end of the low resistance element 12 engages the high resistance element 11. From this point the resistance will also increase uniformly but at a higher rate. This is due. to the fact that the two resistance elements are in parallelthroughout the length of the low resistance element 12 and the effective resistance will thus be lower than the resistance of the high resistance element alone.

- While I have shown my current regulating device with terminals at each end of the resistance so that the device may be used as a potentiometer,'the device may obviously be used as a rheostat by making connections only; to the terminals 16 and 17.

rtain features of the specific embodiment of my invention disclosed are described and claimed in a co nding application of Donald R. De Tar, erial No. 294,277, filed July 20, 1928, and assigned to the sameasas as this invention.

. e I have described my' invention as embodied in concrete form and operatingin a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto since, various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States is l. A rheostat comprising a main resistance element, a movable contact member cooperating therewith, and an auxiliary resistance element electrically connected substantially throughout its length in parallel with a portion of said main resistance element so as to vary the-ratio of the change of resistance upon corresponding movement of said contact member over the different portions of said main resistance element.

2. A current regulating device comprising a plurality of resistance elements having different resistances per linear unit, means for holding one of said resistance elements substantially throughout its length in parallel, electrically contacting relation with a portion of the other, and means for including the different portions of said other resistance element in a circuit.

3. A rheostat comprising a pair of resistance elements, each of said elements comprising an insulating support and a resistance conductor wound on said support, means for holding one of said resistance elements substantially throughout its length in longitudinal electrical contacting engagement with a portion of the other, and means for progressively including the different portions of said other resistance element in a circuit.

4. A rheostat comprising a pair of resistance elements, each of said elements comprising an insulating support and a bare wire resistance conductor wound on said sup port, means for holding one of said resistance elements substantially throughout its length in longitudinal engagement with a portion of the other so as to bring the turns of the two-elements in electrical conducting relation, and means for progressively including the different portions of said other resistance element in a circuit.

5. A current regulating device comprising an insulating base, a. high resistance element mounted on said base, a movable contact member cooperating therewith, and a low resistance element mounted in contact substantially throughout its length in parallel, electrically contacting relation with a portion of said first mentioned clement so as to vary the ratio of change of resistance upon movement of said contact member over the difi'e'rent portions of said high resistance element.

6.. A current regulating device comprising an insulating base, an annular resistance element mounted on said base, a contact in sliding engagement with said annular resistance element, and a second resistance element of lower resistance than said annular element secured in contact substantially throughout its length in parallel, electrically contacting relation with a portion of said annular resistance element so as to vary the ratio of change of resistance upon movement of said rotating contact over the difierent portions of said annular resistance element.

7. A current regulating device comprising an insulating strip, a resistance conductor wound on said strip, a movable contact member cooperating with said conductor, a second insulating strip, a second resistance con-- ductor wound on said second strip,said second resistance conductor being of different resistance than said first mentioned conductor, and means for securing said second conductor in parallel, electrically ccntaeting relation with a portion of said first conductor, so as to vary the ratio 01": change of resistance to movement of said contact member.

8. A rheostat comprising a substantially circular insulating base, an annular insulating strip, a high resistance conductor wound on said strip, an arc-shaped insulating strip, a low resistance conductor wound on said arc-shaped strip, means for securing said low resistance conductor throughout its length to said high resistance conductor in parallel, electrically contacting relation therewith, and a movable contact arm for making con tact with said high resistance conductor.

9. A current regulating device comprising a pair of resistance elements, one being held in overlapping contacting relation with a portion of the other to reduce the eiiective resistance per linear unit of the overlapped portion thereof, and means for including the diiierent portions of said other resistance element in a. circuit.

10. A current regulating device comprising a resistance element having a substantially constant resist-ance per linear unit, a movable contact for progressively including different portions thereof in a circuit, and a. second resistance element held in parallel, electrically contacting relation with one portion of the first element for varying the ctfective resistance per linear unit of portion.

In witness whereof, I have here n my hand this 19th day of July, 1928.

WILLIAM L. BONE").