llel)ort oi-i the I)estrn end Con3tructiori of Fido Tone E@elay Apperstus on-,--.'--,uLcontract under Contract lie first apporatiis built was de@signed on the principle of a con- stant tape speed of about 40" per second nitli a variable distnnco betrieen the recordinv, and playback heads. The recording head 'Was fixed In position and the playback head wes movable on a truck v)iich wns do3ir 'I'he tape In the form ;nod to preserve ttic mlicnment. of iin endless looo nos carried overtto licht l2ow inertia palloysi, one of vtiich v:ss kixod and the other lievinr, a sprin(@ Mountin,- C,) , @Nhich .maintained a constant tension on the tape* 'Die sound quality was fair. 7ho loop of tape of overall length st@out 2 feet appear2ed to r qlie overall ,,ivo adeqtioto rosults for poriods tip to one-linif hour. necord quality, ho@,jever, ras not by any means equal to th.0 !."a equipment. Althou-i-i lo%,Yer atislit-y ar2iplifiers (P( Y,,ero used in t@iis %%,orl,c, the main difference in quality was noise inherent In the tope and hcad system used. I (;onseqtientl- nstont !-iced ,ioporation device rtis ,@t a variablo speed co desicned and built. 'The hcG(Is riere,fixed in position et the rilnimun diatnnco (1"). 1,he endless loop of tooc %@,a3 driven by a variable speed LC motor,, iisin- a 6 volt storaf_,e battery. Since an overall speod rsnfrc of at least 10.1 %,js.s desired Y.,Ith E,,oo2d torque over tho ren-cet the use of a resittencel,iri the field vies found to be lni3dequat;. I'h,e desired cariditions %@ere mode by varying the or,-icture resistance and the field resistance sirrulteneoual7o but in opposite directions, 'LEits %-;as accomt)lis2hed by 9 -iodific(l potentiometers fixed rosistance combination betv--,,-,n the field and tli.e, uri-,ioture. In this way., a 2-1---.1 !3pood range ras obtained @,7@ith t,ood torque# ]lie ren@f-o of delay with t'-Iis equipment vlios f2rom about 0.02 to 0*4 seconds 'llie nolso level of th,3 machine ras fairly vllgh,, apparently due to ltiodcqiiate alif-@nment and tracking of tlio tape, it boca-io oppnrent tritit constrkiction of a hi@,,Iior or,-ior of acci)-racy vies necessary. It decided 2to lq rd recordinp, modify tl-ie @' r ,,noco i.init by 1,,Popl.nrr n fixed rolotionship batriern the, liencis and a con- striiit tupe spood by incli).dinC-., r7ice2ns for var-.7in,, t,,,e lon(rtli of ttipe betzeen tli-- fli.ed record and playback boadso "Ltits afln be done by an orron!-ement pulle7s., the middle one of' v,,hich con be varied in distence from the heads. In usin(@ thig ,rothod, the amount of4 tnpe bety.,ecn the 1-iouds is t%,viae t)-to aonnrg*.Ion of tl-io middle roller fron the heads, ',','hcn this upceratus was cotistrticted and tested,, it vins.found that ttie introduction of the auxiliary cquipment lri tllc r,,-,If.,@ibortior)cl of tli.,3 lif3ot3s lipset the ahloldinc, syst,ori tind i,esi.ilted in the introd.uction of n fsir oir@ount of n,)iseo C,onscqitent- ly the po2ition of tlio heads2 Y;i;s -7noiVio,,3- to the e:-:tent t!,at tl-ley v.era turned at JGOO so t@iat tho ,Lnpa fecocl each oti-ior end were abot.it 1/411 i3part. i@ shield wa-q inserted betvccn ttie hostis end a sniall2 pulley -motint;ed on t3 st-Left ri-innii-if,,, in micro bell basrinf_,,s 'Was tised to position tlio tape,, '.nio ecparotion of ti-iis pulle7 from the liendn ivas controlled b-y-P dial operstin!,,, a carrier 2 @,e. @.lie dial r. e. s colibrated directl-@r in doln-y in seconds,. 'f')-ils device viss extensivel,7 tested In tiie laboratory vnci found to -,,Itti 15" T)or second telpe speodp dolay rlitcli could te v2eric.@l bot7;eon O.Ul secon@is snd 0.5 see,)ncls ritli overall sound qualit-y opproximetel-y equal to that of t@ie oritrinal 11-lognecord iinite Ilia apperstiis wee tested by moons of a steady-ttiousend cycle Input from an audio frequency oscillators 2 71,he sound from ttie playbeek lioad visa exoiiiint3d. anci found to bo of adequate que,lity from the standpoint of roi-,, flutter and noinas iiiis ,nsc'.iine was in.-itlgllcd in tti,e lptioratories of L7-1 --------- 0-'" and tc3sted enterisively -.,ith actiael subjects. 'j'.he quality of reproduction steadily end reoldly deterioraterl and after several doys use become co-.npletely Inadequate. !!'aamination disclosed the fact ttint the Pnachanicul rugL..,,ednegs of the equipment vas Inadequate for the uonditions of use* A small drive pulley ras constructed for u.se to tl-io.standard ',"a@,necord le equipm-.Yit v,ri.icii would permit a @lelay of 0*3 seconds with the 7-1 2 @)tt per secot)d tape speed for use with the atiLJeots -viiila a new spl)oratus was constructede It r4-@3.3 docicterl tlist the cliff iculties ericotintered in previous clesigns could bast be avoided by usinr@ a varloblo tape speod witli the st2ond.ord ernsop record vnd pl.pybook head,essey--bly of the 1,!srnecord unit. Ttic standsrd "ac,.necord 7,1,itor viliicsi-i Ii3 L:zynchronous rill be used to drive a Oise at variable Olstances fro,,i the nxino a 2drive free from @vow shotild be realizable onO n 1-10 ',Mpccd ran-Co n topo -,ii)oed of -'-" to %"10" per seer)zicl r.111 'Lie obtainsble -rfilch %Vill P,.ive a side tono delay from O.OE to O.E.seconds. 'lie 2 oEiiocord recordin,7. unit 1-in:s tcon completel- .@ismantlod onc) la @-ebuilt with tl-iese ,nodif lestions. Ilbe stniidard 'arnecord e,.idless loop tnpe device -.v,ill be used. It tiol@39 up to GOO fac,,t of 2 t,qD-3 tI)i3,Li the ti3pe will holic o lonf3 life, de:3iCn,, cfIcotirse, 3,cffore fi,orr, tlio diestiventsi3(5 t@int c parini)nent record of t. rie to3t of t,,c siiLJect Is ii,)t obtained,, tut It Is felt t,iot the ellvants!-os r-ill co,-,.ipenecto for tiie necesulty of i)slnc, su.;tlliary recordino equip-,rent. 1'11.o "tor drive is presontl7 bol.n,, asuoml)led. 4 1.@ifficulties 'fipve beon et-icountered bt--catice of ttio necest:ity t'kict t'i,io driven (lise be free flostin,o Completioti of the unit within ti7o noolits is contemploted, -2/24/%r.-3