Show rt OF ma va MP NOW THIRD ELEMENT IN THE VACUUM TUBE grid added to fleming valve by dr lee deforest was a big improvement any deleo which pass elec t in lit one alre alon and wholly or partially ob obstruct strut the flow in the op tyli nite dir petion ID Is termed a rectifier fler became because ahen hen connected in the path af an alternating current it will III press ane aie hulf af if each cycle tind there fore th elih circuit will ill be lie traver wd d ly by dirt direct et current A recill fler miro 1 stilla id to poi til ine aning of courton that it ill conduct electricity in one dt only if its ability to rectify cur reuta rents of extremely high frequency de ite its application in radio ite its ability to rectify high frequency currents the tile two element filament and plate tube can be used in a it radio receiver as ail a detector flit VI to 11 a simple radio receiving le circuit employing tills tilts type of two ele ment tubo tube in jn place of a crystal detector dr J A flaming fleming of london rny land as the first to ube a boele t element tubo tube of the type just described as its a medium of high frequency radio current currents fleming tailed called his product a ai alvo e because it bould let current flow flom in one direction but not in its the other direction the tile fleming 1 valve as ats a forerunner of tho the bacu of tit the grid ald circuit 13 I 1 J X 1 L the hatter in its the tile acrid kt ld circuit in ailed 1 the C battery bat pry an au av turl let us 11 pose that 1 buttery hattery Is zero the opt rit 0 tion if of the til atral tuba alx then thell tf top exactly like that u of a two to vice elec trod till junt ar an though there pre no not grill 1 like a two electrode tube hen the ill C D 1 Is brought t too lix by tic tile A hattery 1 a sirvain of electrons will bo b alv gly en which will III he drawn over to fit the plate 1 V in ut at it potent potential lal with rap t tu tile ie by the 1 it attry battery nt try now if the grid Is made with to the filament it ir lit twit it to acri Hc lente enite the tile flo flow of flip elee iron tron fruit fruits tho filament to th plate lute if the ali grill 11 ix in made legame alth ri to the the tile alo of the el lf ettron tron stream from the tile nin ident to tho laic will be tw retarded or iri lit other orila 1 by making the grill 11 or nega ilvo with to the nt it 1 im possibly pos 1 to inen itse or coun the antlee charae ohp th third 11 or grid thue thus offers a mi ans of 4 trolling the tho current in tin the YZ pint plate circuit ii anding the tile plate potent lid li or the nt temperature the characteristic buwe of a shieo electrode tube 1 ahon 1 in 11 fig VIII thih olla gratis the relation of grill 11 to current ams tuning alint the teni tire atilia lafitte coustant it can hi ito awen 1 from froin the ali curve that by upp liK at 0 neg 11 lithe potential of u galup F to tile grill olt th plate current tilts he 11 to ta zero tile negative harge on mi the tile lie hae the tile effect of R nen benthe the P wah rt to to tit the inuring the nettle chargo ciar ci mr so satning around lie the iii the 1111 Pl 1 etron annot leave it on th other licud if a 1 le tle potent fid cf if ahlup F be applied aik Q 49 ery gey w te f ey aue aa SIT un uni tube of today marked a very ira im port portent tint top step in the progress reee of the nullo art the fleming vuka bow hom r ivr er iu in itu its original form was not much better than other tonne forms of or ineis then in use and owing to the greater ruggedness and ease of manipulation of the latter did not come mme into gener senor ail bijole y pit a tit detector dr lee loe DeP deforest De Porot orest an american gnit gres lly itly improved the fleming eleming vahe by adding a third electrode called the grid which served the Yunc junction tion of a control element and thua thus made it tuble tl to utilize the feeble incoming signal corrente currents to control more powerful po wertal local currents the three electrode tube of DeV delored De loret arest to I 1 the tube need so today i il the e third element fifth in lecal A hd a 9 grid and from rom w ach the three dec elec a tube lt name warf wait placed by Pe deforest Forest between tu filament and imd the plate in n the path of them ct rons the no grid ie Is abed plate or mesh of fine wire through the f of 4 aich the electrona electrons elec tronA must pals ln their journe Jour nev fron the moment to 40 the he plate I 1 fig is a sketch of the circuit of a three tf elect electrode rude vacuum tube and MIU le in the an the jn in fig ill for a two lament vacuum ube nith the ad to the grid ath with respect to the mn ant the tile or cir int ent tit tag flow in lit the plat plate circuit applying a greater positive tIp poten aal yal than F to tho til grid respect 0 ito o the alia anent will not un an Inc increate in thi tile f A r JV 0 if PIP jw plate cur current because bemuse thi electrons gt to 10 off are being attracted to the pint plate and wd when adie me grid la Is maintained tire with respect to the filament 1 11 current wall flow lo 10 the grid cli cir cult ot 0 its being bews positive e 1 will ill attract the md and hate hae tl charge given tip UD ti it by then |