US 1904352 A
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Description (OCR text may contain errors)
A 1 l Apnl 18, 933 L. BRADLEY 1,904,352
' ELEGTRICAL REsIsToR Filed Nov. 23 1928 -2 Sheets-Sheet l /fi IHIIHIIIIHIII A if C: ri fag ki in ,Wm/y /e Y .l 1mm l un. f g .W j@
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mesa-J Apr. is, 1933 l UNITED STATES ,PATENT oFFrcE LYNDE BRADLEY, F MILWAUKEE, WISCONSIN, ASBIGNOB, BY IESNE ASSIGNmTB, :JTO ALLEN-BRADLEY OOMPANY, OF MILWAUKEE, WISCONSIN, A. CORPORATION 0I' 'WISCONSIN' ELECTRICAL RESISTOB lApplication med November 23, 1928. Serial I0. 321,386.`
This invention relates to certain new and useful improvements in electrical resistors adapted particularly for use as voltagedividers or potentiometers.
Many types of variable resistors adapted for use as potentiometers have been produced in the past, all of which however had an unchangeable definite ohmic limit and, therefore, this invention has as one of its ob]ects to provide a new and improved potentiometer having means whereby its effective range may be readily adjusted.
Another object of this invention resides in the provision of a potentiometer which inis substantially equal to the mean or average resistance the potentiometer is to maintain.
Another object of this invention is to provide a potentiometer having Aa fixed resistance readily detachably connected across its end terminals whereby the potentiometer effective range may be varied in accordance with different requirements. y
A further objectv of this invention resides in the provision of an improved resistor or potentiometer in which infinite variations of its resistance values may be obtained.
And a still further object of this invention resides in the provision of improved means for simultaneously and inversely varying the resistance value of the two units of a potentiometer.
With the above and other objects in view which will appear as the description proceeds, my invention resides in the novell construction, combination and arrangement of parts substantially as .hereinafter described and more particularly deined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made' as come within the scope of the claims.
In the accompanying drawings I have illustrated one complete example of the physicludes a fixed resistance the value of which' Aaccompanying drawings, in which like nuv cal embodiment of my invention constructed, according to the best mode I have so far devised for the practical application of the l l l l o v Figure 3 is a cross sectional view taken vthrough Figure 1 on the plane of the line F igurel 4 is a diagrammatic view illustrating one application of my improved potentiometer, and l Figure 5 is a view similar to Figure 4 i1- lustrating another application thereof.
Referring now more particularly to the merals designate like parts throughout the several views, 5 represents the body or housing of my improved potentiometer which lis preferably formed of insulating material and as a pair of arallel wells 6 and 7 extending downwardly rom its upper surface. Lining the cylindrical walls of the wells 6 and 7 are metal sleeves 8 the upper peripheries of which are ared outwardly and extend a slight distance above the top surface of the body for a urpose to be later described.
, assing through the bottoms of the wells are Contact members 9 and 10 having enlarged heads received in recesses 11 in thebottoms of the wellsand having stems extending through apertures 12 communicating with the recesses 11 connected at their outer ends with terminal members 13 and 14 by riveting or the like. The terminal members 13 and 14 are disposed in correspondingly shaped recesses 15 formed in the under side of the body .5, and extend beyond the opposite sides of the body to provideterminal lugs 16 and 17 on one side and resistor supports 18 and 19 on the other side for a purpose later described.
Resistor elements 2O in the form of powdered material having the desired degree of conductivity are positioned in the wells 6 and 7 to be selectively compressed by plungers 21 and 22 working in the wells 6 and 7 respectively, to vary their resistance. .The plungers each consist of spaced discs 23 and 24 having a felt or other like ldisc 25 o greater diameter therebetween to frictionally engage the sleeves 8 in the wells and prevent rotation of the plungers, the plunger units being held together by rivets or the like 26. The upper disc 23 of each plunger is provided with a key hole slot 27 in which the grooved ends 28 of actuating' members 29 and 30 are engaged, to provide means for longitudinally moving the plungers.
The actuating members 29 and v30 consist of micrometer screws having square heads 31 and 32, respectively, and threaded in suitableapertures in a plate 33 positioned across the top-of the bod-y 5 and closing the wells 6v and 7 and the flared peripheriesof the metal linings 8 of the wells being disposed slightly above the top of the body member are thus electrically connected with the metal plate 33.
The square heads 31 and 32 of the actuating members 29 and 30 are slidably received in square openings in meshed pinion gears 34 and the actuating member 29`has a stem 35 extending outwardly to mount a. knob or the like 36 whereby simultaneous and opposite rotation of the actuating members threads one into and the other out of its respective aperture in the plate 33. As the direction of rotation of the actuating members 29 and 30 is at all times opposite, it lwill be readily apparent that when one is threaded into its aperture to compress the resistor lelement within its well, the other is threaded outward of its aperture to relieve the pressure on the resistor element within its respective well, thus decreasing the resistance of one well and increasing the resistance of the other.
A cover member 37 having the lower edge of its side walls recessed to provide a shoulder 38 and a peripheral ange 39 is fitted over the plate 33 with its flange extended therebelow to engage over the adjacent upper edge ofbody 5 and maintain the parts against shifting, rivets or other means 40 extending through aligned apertures in the cov'er, plate 33and the body 5 retain the several parts in their proper assembled position. Y
The rivet 40, positioned at lthat side of the device from which the terminals v1.6 and 17 project, preferably has a tight fit in the' plate 33 to `form an electric contact therewith and a neutral or middle terminal 41 `disposed in a recess 42 formed in the under side of the body member forms a washer for the lower end of the rivet and is thus electrically connected therewith land through the plate 33 with the metal sleeves 8 in the wells 6 and 7.
The cover member is apertured in axial alignment fwith the `well 6, as at 43, to receive a mounting bushing 44 adapted to be passed through an aperture ina panel, not shown, to which the device is secured by alclamp nut 45 threaded on the bushing 44.
in electrical connection with the unit terniinals 49. The value of the resistance unit is such as to be substantially equal to the mean ory average resistance `the potentiometer is in'- tended to maintain and in this manner it is only necessary to replace the unit 48 to change the range of the device, which, therefore, provides the potentiometer with an unlimited range.
The circuit from the middle terminal 41 to either of the terminals 16 and 17 is through the adjacent rivet 40, the plate 33, to the cups 8, through the resistance units 20 within the Wells, where the value of the current is adjusted, and through the Contact members 9 and 10 to the terminals 16 and 17.
The uses to which a-device of this nature may be adapted .are numerous and in Figure series with the plate voltage'of the first ther# mionic tube 51.
From the foregoing description, taken in connection with the accompanying drawings,
lit will be readily apparent to'those skilled in the art to which an-invention of the character described appertains, that I provide a new and novel potentiometer or variable resistor which functions eiiiciently throughout ,prac-i tically an unlimited range andi-n which in# initely small variations of the resistance -values of its two circuitv branches may .be obtained.
' What I claim as my invention is.:
1. A potentiometer, comprising two variable resistors electrically connected at one of their ends and having their resistances variable under pressure, means for simultaneously and inversely varying the resistances of said ln this instance, the terminals 16 resistors, a fixed resistor, and common terseries across the terminals so that the sum of vminals for the other .ends of the variable rebothis always constant, and a fixed resistor sistorsv and the fixed resistor wherebythe mounted on Vthey outside of. the supportin lixed resistor electrically bridges said other member and electrically bridging the space ends of the variable resistors, said common terminals yto deline the effective resistance 7o terminals being adapted to have conductors 'across the terminals, the value of said-fixed attached thereto to connect the potentiometer resistor beingchosen to adapt the potentloin an electric circuit, and said fixed resistor meter to a particular circuit requirement. having a resistance value to adapt the poten- In testimony whereof I have hereunto tiometer to a particular circuit requirement. aiixed my signature. 75
2. A potentiometer comprising a body member having a pair of wells, a resistance LYNDE BRADLEY. element disposed in each well and composed of compressible material the resistance of x which is adjustable b pressure, plungers 80 movable into and out o ysaid wells for a plying various de rees of pressure to sai elements, means or simultaneously and oppositely moving the plungers, contact members electrically connected with the resistance ele- 85 ments within the Wells, and a fixed resistor carried by and electrically/connected with the contact members whereby thevalue of the fixed resistor defines the effective resistance value of the potentiometer, said con- 90 tact members being adapted to have conductors connected therewith to connect the potentiometer in an electric circuit, and the value of the'fixed resistor being chosen to y adapt the potentiometer to a particular cir- 95 cuit requirement.
, 3. In av rheostat, a supporting body, -an adjustable resistor element carried by the supporting body, terminals for the adjust'- l able resistor element rojectin from one 100 side of the supporting ody, and a ixed'resistance element supported jointly by the terminals and said side of the body, the lterminals being adapted to have conductors con- 40 nected therewith .for connecting the rheostat 105 in an electric circuit, and said fixed resistance .elen'ient being electrically connected with the terminals to dene the overall value of the rheostat and ladapt the same toa particular circuit requirement.
4. In a potentiometer, spaced terminals",`v f two electrical resistors, one connected with each terminal, means to simultaneously and A oppositely vary the individual resistance of p said resistors and connect the resistors in. v U5 series across the terminals so that the sum of both is always constant, and a fixed resistance mounted on the potentiometer and connecting the terminals tovdeline the effective resistance across the terminals. g '12 5. Apotentiometer comprisin a supporting member having -spaced poc ets,'spaced y terminals each having 'a ortion extending i'nto one pocket, a variable resistance element i'n each pocket in electrical connection I 125 with the terminal' part therein a cover to a close the pockets, means carried bythe cover to simultaneously and oppositely vary the individual resistance of .said resistanceA elements and connect the resistance elements inl 130