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‘A Magnetic Curve Tracer Ss nate fe staph, wo seinen The ery hs FOR accurate determinisions nf hysteresis loops and inital magneti= ation carves of mayne sperms. a laborious routine invlving the ve of ballistic calvanomater is ueuallynocessary. This arle describes a apparat os i enn of whieh these curves may be obiained photographically with qismitalive acamey. Attempts to device Sich a orheme have previously been tule. Ening descibes one ‘which was wed sith shor, thick operinens ia a magaetic yelk Fleming? invented ¢ devier, the Cangawraph. which made use of snagnetomecer and hs che avantage of aking dose the use oF ‘one thin, -pevinens snag dy ecsrent art dearest fives je Jolnmesseyerie the most recently publihed lesige, ftbodying a yaw ini anater and a Bray tube oullograph Pie hyscesgryet fe eed th Lequercies ef she under oe eyes rer sina or ghey, ed eanceguenty “nraies am erly curren Hoot adinadvantage ra grant mare meceiremen’s “The assatest ditinley fom storys Iwo tn devise an iesrumens which would aceusstely end re atl change in magnede fax in The specimen. The eal iszerument woul be» dwmeter with Festorng force: asl aa filetion. Pinvietem sce on rhe market it ‘hich the restoring locce is negligible sy over shoct periods of time Sorin whieh there is ne resin ton as where the fit is appreck Sables bus iii eqn that che msigreticrvee ave 9 perio of more thas a few srvomlsy much Husmeters are out of the question. Ta fdition they require that the seireh coil he of seh lowe eesnance that if tmest fave feo few turns for rie ith Tong hin eens Ivhish the uy it small. These diieltee have been overcome in the Uppacatusdersle ion, ia waieh the principal feature isthe wee! a Sal Bal eee Pak Soy 86 89820 stusmeser iv which the suspended oi has its resring torque counter Ince for all deflections within range solicient for anurte lineation of magnetic curves, Descatratos or rats Avante “The mpesatioa of the appari sm follows: ny sensitive, plato \Sertsie cel in ted with a V-shape sas shown in Fg. 5a bea of Tigh in eflected fewin the mine of rhe fusmeter and focal 9 the SHU of the photo-eoctie cll, whieh 4 enanected. in series wil Source of emf, sess the tera nf The fusmerer: the ef. it Ejuctod once forall to seh » ylue That. he Besant wes when ft the nar ead of the aie, aL any wtler position the current cone trolled ly the cl wll cele» tamu i the Runmeter el whe just Thlances the rcstosing torque ofthe sampension. The Auster Mefleeien tll then be puoportgnal w uhe change of dus wich has tect wehin the seach ool Ss Lemay be toad nroeace to shape the alt emiially to eorveroanl C0 E26 dna! sews tlties of che protuelectnic roll a¢ diferent saa he Rexmeter sel Lee ne Northnap tye 2290 HS yefeanometcs 1 hoe rts damping fesitanre nf aout 200.MH olay a hen esl wit alan one Fnrel huis ine exter wre ie much over dame "The ince lus for rexivering the detottons phocogeaplically, ad for ehanging the magnetic: il in sérum D, carrying photographic paper is placed in a fight-tizht box povided with along, nazcow sit parallel to che axis of rotation of the rum, A bean of ight fom a soeand lamp is refccted by te smeter mirror and focused on the sit. This beam is refected by the same rhino which reflects the beam onto the ptotoslectic cei, the oo ab Bo “XK, a barns being incicert as efor: angles Autachell tb the shalt of the dra inan arm A, which se lng the rhenstan Re Latiery 8 ‘a conncettd getere R, and a center tap soldered wit. Between te firm Tad the center expt veeving ean is peuced whieh sapped tothe fed coil This emi nrvernn fix ign everytime the arma sides past the center of the rear, sol the liter i exeved St 3 ronnie elutes ha the Gl entree wl be proportional to the rg oti of the dr Frnt esi for sere usteat. "The earch col Sof Fig. 1 placed within Fy and cowsegueatly when 2 ie tated it moves the porog.aphic paper pact the lic so chat the “stance wave) unposienal to she change infield eserens, while = "he mame ste the Hasineser Cebeete te Sear af ght along rhe alien Pat the deflection 's ofoperonal te the dire Sacral of the ha gos fe within S.”As the ecum is ures from ee poscion to anecher, {curve with rectangular anes i thus registered, the seal of shih may he calfostec in ermeot and fd. igs 40 Tare some exannpies fh cavves taken sith ehe appari InFig. Atheectricalcieuitsareshiwn in detail, Ry ie the rheostat, controling the ek curt nn! Ai he aru which rotates with ie Aivum, The bactery He sppties the eld cutest, ane Bo Frise the tem Jor the pot eerie cell the vale of the teal apotied te the letsr boing regula by The potential divider and dre LB, in series with the 10 megebm resistance Ry are ume to slance Sa need oleracea te prt Geet) [ tsb saloon oo = wis due sua light. Rand Ry ave dj th i the specimen, in ower to ker the dest limise The mutual aductan the petals peared aS whee no-spcimen i wii thal te Fuxiwier dlefietion fs wonnrional tw the change in B=. The ‘drum is convenient rotated by am eletre motor eonnected by gers 9 that thes makes about me revel ion in nates, aa Sesiable thre this rate vale. Te menor maybe revere 39 ‘es complete Hysteresis logs may he recorded ig § Hyer a fa Jn setting up che apparatus the photo-teetis cel! mey be con seaieatly places ahove ef 2eiow the drum, and one lamg chove tle cher, The lamp etd to clhmninete the pkoro-lectre eel! shotld fnuvish a brine bear, and fe was found thar a 250 waet Mans tnjection lamp wae quite satefartn:y. Cstimariay oF Tae Comer ‘The circuit is ealbssted by pesting ¢ krown current throush the etary ofa owen mua islanen, the seu ary of which is tenaeced in series with the earch coil 8. By measurement of the lelecton: produced the cries Insets tH snenlisy of eleetisiy Tesicg Catach che Bucirnies ae Ie eles can be doterined, Thom tas elation cashes laws cones sa elon ge finden oP cnmgnetisorinen waving a gover deletion aye be eeulte, ‘The eliiestewr muy he done in the folosing yanner: Tew Lee esque seinen fe viewer, Ryan he the moguetiviny wil Fle dato ride which wl 14 cheage in che fel ert fav cise dest om she drm eeshown Pye Le drstuntneme, penny eves 2 ametualinducance of fell indurtanoe ob eecoadary cre ‘Tee Lal | hie meat tn at Tetepratng fm: Ee? = 00 = 6, Fe oe ay es seam, B Paid (ae - (ve Bae em hy: at bos passed through che iby, hose By ie she deletion where Ou is tie quaccicy af eel Tusaneces in cine Kew ie 0. relncal when (ee dows. The and the yuimity uf olesuiciy hich Sas peer thos ah he wieter oe any er dees i “This ation mickey it pombe eo determine BFF heated ren Gam lees‘) elomy, hy observing te deection | KGaLow 1 rs be determined onge tr si wr 1 9 womlant cf the thucmerer oats The patts of Q pasting thrush Ry aoe te phoeselectie eel will be eglsible an eecount of thee sigh reintanese Sour way ne ke cnr ye end wish auto til be flection Is doe sly ts she nigcizatian al he specimen, Tt the sistance ofthe flveteler lu tha ab the eccer dar of 2 he denote ip Raat thy lS yoo By he denoted spa. Then Hae fel cowvens jg is vatied slunly enough the Gine lag is the strandacy CGrouie will be aeglibe aul we shall have for the instarcmenoe ‘usvent in the Hinvmeter Now the emf is the search col vec aylit wl where ie the crassa nc of the pesimen and Vis the marmber ft suons in the sear oul, Hy oa Pia Bae finan . wlan (14%) vee MR ARO 4) oe ‘slicing the total egcondry’revstanee when K wes determined, Tis frastion, then, tives — di fo. any aiven defecson i, interme oF Tknown consti. For my tusmetes.& is determized once forall by passing tae cucrent dy thvugh a metus indsetance ad easing the Aeection youn) phlagraphie record. ‘The other constants are ‘hanged in a cilewle wy when the number of turns inthe seat Coil te resistance settings, sad the ernest tH the sple ire change Sacer OF ERROR ‘Since it isthe voltage annie tu the snagaetising cul P which ie proportional to the angle tung wie the vam Aas rotate, there inst hg the Ll eurreat behind the eM seyatenod on the dru, due to the sel indetance of the cols. Added to ths there isa lag fa he secondary du fo its self nductanet, and another Ing due to the time required forthe Semeter tn act ‘The tlre of these ie ta rien he Toop, Fig. 9 shew» cure trac with no magnetic ape i the Rik! coy and with dTCil! so grect that the lag is appreciable, Fig, eso be lta he ales ont vepceeating a ep as een on the ayraratus, and theft bie tp sncespording terete Lee # be ane Saucon ese zeny at the cated loop. it will be innorres fow the iodiated value of Jf by am amount) — 2, such uti he Weld "see held eecstane at that gine thle the doum cor tinued fa rotate ste env wend apnrach By as an asemptate, at Indieste by the str e, Wldijari nn ae40, Bina bere fs mortentarly apprearhing Byte ayimptote. The equation for 1 atany inant i wt pat 8 i) where A isthe time constant of che rei wre Ay not & constant Thus uetion of 1 and TE we stwsne Tt BST x constant Gor fivall segion in the negituchueal of LC, we have, puting A, salto the ern in cnet free Hf, a Bau, iW Combising this with Ra. (8h we have Daa taken wit ow nagaetie specimen eset cow that =i line ‘lation aol eats Ade this chere an nore in v8 geses vate in fo 8 dca ey cuwrens eg Fohnaun hasfoeved an equation fn 11g wit Siahe meets ts tome. pytcable toes Fede pains, sehere pi the esti ee spe, seed Ste radius, This gee sow the total