Show VACUUM TUBE USED AS AN oscillator transforms direct current energy into alternating current of any frequency AJ A a n oscillator a three electrode As vacuum tube has haa the pea property party of the direct current ecer supplied to the plate plat circuit let into an uada roped alternating current of any desired frequency by connect ing ile the tub tube fl functioning tio A 19 Us ax A an oscil ell lator in the proper electrical circuit enameling alternating cuir currena mats have hem been obtained ranging in frequency fre fluency train from ons one halt hair cycle per par second to ta cycles per second in fact a vacuum tube be used as an oscillator 1 la about the only source of alternating current at radio frequency available for foo the anist amateur rity or wave tel tei e graphy and it radio telephony let ep hony are am made possible only by use of the vacuum tubes wh when the three electrode vacuum tube suo aa functioning as an amplifier it was waa explained just how operating the grid at a midpoint of the char ter lur curve a mused t the he plate cur car rent felt to ta very vary synchronously with the grid potential not out only did the plate pint 7 C 17 current wu vary with fill the grid potential im but t if the plate circuit td were tuned t the ha potential variation in the external plate circuit w was a nn sma amplified P filed reproduction of the change I 1 in grid circuit potential in 1 ITI fig g is shown shoon a thres three at electrode vacuum t ube tube with an alternator farm long an alternating dif di arence of p potential to the grid cir mit kt at T TT T the plate plain of the t ube tube pi la caime connected 1 ad to a ell cult con fabling on an inductance L and a capac uy fly 0 which to together form farm a tuned circuit between the points point X and Y by adjusting the value of the i a b a condenser 0 the natural period of the tuned client circuit between X and Y can be made the same mine as the f frequency ot of the alternator ill the alternating grid potential applied ap pp led Z this to the grid circuit at T T W when hen tnie condition allis reached ill the tuned circuit between kam X and if fossaa becomes an infinite loops impedance sea in the external plate circuit oil it the potential variations between twe X and ad Y are now R co maximum loo and od are exact amplified reproductions or of the potential varl variation time applied to the grid circuit by th the alte alternator mator when a three electrode re vacuum ren n to tube ba I 1 is used as A a area of mid ape d i tom a flat current it Is 1 not excited emited by an alternator c connected acted to the ful grid it vir circuit alt instead some of the outa output at of the ill plate comit li Is coupled buck back to th the grid cit circuit it t thus h making til g t the he a W tube self melting exciting fig V il shows how this to la accomplished in place of the alternator that was mas mft connected acted across cm the grid add circuit of at TT to is ext externally excite elefta the tube by byul 9 an alternating current to the grid circuit t there am Is ie tin an inductance I 1 th tha to two A colls 1 I 1 forming farming the inductance I 1 and nd L are placed close class together BO that the potential variations that ex As the tat let between b tween X and Y will be mans oe L y I 1 berred IT irom 1 L to TI tiie can gnu isem circuit through the medium of tile the call 11 1 which he has replaced the alternator any disturbance in the circuits olse arii such a as the tuning of either the A or B battery will rill I 1 cabie a a ell change age between alie lie points X and Y this change A will be it transferred peeved ill from the plate circuit to the grid 11 cir cult by the ran magnetic onetia coupling aing sexist at between the to two coll L and it I 1 0 the frequency at ah which tell the tube will oscillate will depe depend 1 I on a the its va values A of L aud and I 1 while the amplitude A or the as oscillator elliad at will be it determined st mined by the d degree gere or of maid coupling ing that eulata be between the ilia m two 0 colls its L and ad I 1 the grid potential variations variation be fine ed se across raffis the terminal TT T T by the coll call I 1 haw have the mine came effect in the he vista plate circuit as a pan potential flat khe K when K U I 1 the Us amplification ti of the tube gube if tamea air great applied directly to the plate circuit when ilen the plate circuit potential variations w a are just to ur the that edons 1 ID I 1 the th tuned blood circuit barthe between tb pointe if and 4 T and ad both are am increasing and nd decreasing ta together gether that 1 1 ID P phase we the allons la in the tuned circuit tuai will be sustained ned or ne anburn the amplitude of the will neither increase nor decrease de should the potential variations in the plate plane circuit be greater the than th the arndall operating to in the tuned circuit between the points xit X and T Y then the adl bius in the tuned mad circuit will in n crease cressi eI in amplitude do until tit the tube be comnes ht noted at this point peter the ill upper apple and it lower bends of tile the charac chame te curve keep the amplitude of the plate circuit from further increasing As aa the amplitude of the grid circuit oscillations are in crossed |