US1549394A - Resistance conductor and manufacturing process and material therefor - Google Patents

Description

Au M, 1925. 1,549,394

W. S. TYLER RESISTANCE CONDUCTOR AND MANUFACTURING PROCESS AND MATERIAL THEREFOR Filed Jan. 20, 1923 10 6 2 r 5 1 I 9 g ;g:3 i 2 2 9 2 INI 'EN TOR. H/al 4321a? Zyler I TREY Patented Aug. 11, 1925.

UNITED "STATES PATENT 4 OFFICE WALTERS. TYLER, ornnrnsnroar, c'onnncirou'r, 'assrenon, BY MESNE ASSIGN- mnnrs, 'ro commnm rnonoenarn COMPANY, 11m, A conrorm'rron or new YORK. I

RESISTANCE CONDUCTOR AND MANUFACTURIN' G PROCESS AN D MATERIAL THEREFOR.

Application filed January 20, 1923. Serial No. 613,860.

- To all whom it may concern:

Be it known that I, WALTER S. TYLER, a citizen of the United States, and a resident of the city of Bridgeport, county of Fairfield, and State of Connecticut, have invented certain new and useful Improvements in Resistance Conductors and Manufacturing Processes and Materials Therefor of which the following, taken in connection with the accompanying drawings, is a specification.

This invention relates to resistance elemerits-i. e. conductors of high resistivitycapable of being calibrated to any desired resistance value, and to the method or process of producing the same.

An object of the-invention is to provide a relatively high resistance unit having relatively small dimensions, and with practically no inductance or capacity, this unit being especially applicable for use in radio-receivingsets. v

Another object is to provide a resistance which can be readily calibrated to a prede--' termined resistance value and without'altering its composition; and which, moreover, is not materially aifected by small or ordinary temperature changes, and yet is capable of permanent change through material variations in temperature. A further object is to provide a resistance conductor whose resistance value may be raised by reducing its cubical contents, and

yet lowered,

bfy polishing or rubbing its surface. Also, i t

he resistance becomes too low by this polishing or rubbing, it may be inunit structure adapted to have both -a plurahty of essentially predetermined resistance values, and also an value.

Then, an object-is to provide aresistance unit having a condenser effect.

Finally, an object is to provide a non inductive resistance having little or no condenser effect.

lVith these and other objects in view,as

will hereinafter more fully appear, the invention is described in the following specification, taken in connection with the accom-' panying drawings, in which- Fig. -1 is a-perspective view of a composite form of the invention, including all of'the novel features thereof, but disclosing; of

easily variable resistance course, only the structure of the invention,

the composition and process of manufacture being hereinafter brought out;

Fig. 2 is a magnified, cross-sectional-view thereof, taken on the line 2+2 of F igf I;

In'the drawings, for illustrative purposes only, the article is shown as rectangular in outline and consisting of a slab of the greater resistance material 1-, having a greater conducting coating 2, this coating being formed by rubbing or polishing in manner as hereafter explained. The slab is a composite structure arranged to have the various characteristics heretofore suggested.

One part of the unit, marked B, has three I binding-post terminals, 3, 4 and 5, one of whichas, for instance, 5is movable longitudinally toward and away from the others by being mounted in a longitudinal slot formed in the unit. This'is accomplished 'by unscrewing both the lock nut 6, Fig. 2, and

a the binding nut 7 ,on the stud screw 8, thereby releasing the conducting washers 99 from gripping contact with the surface .of'

the unlt, and permitting this entire bindingpost assembly to be moved in its slot, and

-soalter the distance between the two terminals 5 and 4, or 5 and 3. Moving the terminals together reduces the resistance, and vice versa. This structure constitutes not only a novel means of calibrating the unit to any it from the unit itself. Thus there is to posts 3, 4, and 5, except that the stud screw 14, is slightly longer to accommodate an insulated .washer 15, as shown in Fig. 2; thiswasher, in the embodiment shown, having also a hollow tubular portion 16 adapted to house the studscrew 14, and to insulate provided a binding- 20 tact is made wit the resistance unit on one surface only. By' inserting the bindingposts in part A of'the unit in reverse position, as shown at 12 and'13, Fig. 1, contact is made between the top surface at 12, and the bottom surface, at'13. Thus a condenser is provided in combination with the resistance unit, its effect being controlled, for instance, by the distance between the conducting plates 11-11, and the distance between :3 .the terminals 12 and 13. This composite structure, with its plurality of. binding-posts, provides a convenient means of getting a variety of resistance and condenser effects, simply by connecting to various pairs of binding posts.

I 1 Various substances can be used for the non-conducting .and the conducting elements of the compound. As the conducting element, it is preferred to use graphite. For

40 the non-conducting element, various substances or their combinationscan be used, preferably a plastic compositionincluding china clay Congo gum, and shellac, in proportlons bout the same as that used in the 4 manufacture of phonograph records-as, for instance, more or less, of chinarlay; 5%, more or less, of Congo gum; and 25%,

' more or less, of shellac.

- These ingredients are mixed in a finely 50 divided state, either granulated, .but preferably in powdered form, the finer the ingredients the better, as it obviates any slight ares which might form 'between the'gralns of granulated material. 7

To this non-conducting composition is added graphite or other conducting material In a PIOPOI'UOH such that the approximate final resistance value of the unit will be approximately as desired. All of the ingredients, having been brought to a very fine state, are thoroughly mixed, preferably in the presence of heat and allthe particles of the con 7 are divided or separated non-conducting material.

ressnrc, so that ucting material l iyilparticles of.

e more intist structure in which conresistance.

mate the mixture, the better the result. The heat, when used, serves to melt the gums in the non-conducting composition; and to aid in more thoroughly mixiugthe various ingredients.

After the material is thus mixed, it is heated on a steam table, and formed into suitable blocks, or other units, under a set of molding dies. It is then removed and allowed to harden. The terminals may be embedded within the composition at the time of ressing, or inserted afterwards.

Applicant has discovered that, in addition to theknown ways of calibrating each unit to any desired resistance-such, for instance, as altering its length between terminals, or the resistance value of the material itself-- 'the same result may be secured by removing the exterior surface of the resistance member by abrasion in such manner that no polishin eflect takes place. Also, and in place of th1s,'by the useof a solvent, such as alcohol, for dissolving away the conducting graphite coating. By thus removing the coatin or the member, the conductivity 0 the skin 0 body, as a whole, is largely reduced, or, which is the same thing, the resistance increased. a I

Another means of calibratingthe resistance unit for an increase in resistance, is to allow current to pass through it sufiicientlystrong to effect a heating action or to otherwise heat the unit. The shellac in I the composition will be melted and caused to flow more completely around the different particles of graphite, and so eflect this increased resistance.

Another means to alter the resistance value, is to actually remove suflicient of the material between terminals to appreciably alter the cross-sectional area of the unit; this also results in increasing the In the event the unit has-thus had its resistance increased beyond the desired, amount, a reverse calibration effect can be produced by polishing, so as to bring the aphite particles on the surface into more intimate contact.

Obviously, various kinds of ingredients, suitable for the purpose stated, will suggest themselves to those skilled-in the art. Likewise, the proportions of these ingredients can be varied within quite wide limits, d e pending upon the characteristics of the spe cific ingredients used, and the distance between terminals of the resistance, and the amount of resistance desired.

Therefore, itis understood that the scope of the invention is not to be considered as limited to the particular materials, structure, and method described, but instead, solely by that covered in the appended claims.

Having thus described the nature of this invent-ion anda preferred form and method for same, what is claimed and for which Letters Patent of the United States is desired, is

1. The method of manufacturing resistances, which consist in mixing a clay, a gum and a shellac with graphite, to form a thermoplastic material, in molding the composition to the desired form under the application of heat and pressure and in allowing it to cool and harden.

2. A resistance member containing a clay, a gum, shellac and graphite.

3. A resistance member consisting of a clay, a gum, a shellac, and a suitable conducting material intermixed therewith.

4. A variable resistance including a body portion of predetermined resistance, a pair of binding posts secured to said body, sheets of insulation material spaced from the binding posts and contacting with the body, sheets of conductor material disposed on the insulation, and a second pair of bolts passing through the laminated portion of the unit, and each contacting with one of the sheets of the conductor material.

5. A resistance unit containing china clay, Congo gum and shellac, mixed in approximately the following proportions, china clay 70%, Congo gum 5% and shellac 25%, together with graphite.

Signed at Bridgeport, in the county of Fairfield and State of Connecticut, this 18th day of January, A. D. 1923.

WALTER S. TYLER.

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