Ogden Standard-Examiner | 1922-06-28 | Page 9 | Edison's Test Led to Vacuum Tube Detector

EDISON'S TEST LED TO VACUUM TUBE DETECTOR Wisard'B Tinkering Brings Cut Invention Important to Wireless Hjf PAI L I fiOnUvi' An'Hrlca" JForesnoM Itmllu intliorit) There .va--. little though: In thl 'nliid of Thdhias A. ISdlaon thu dlsoovvry which hi made anl to wnlch, uihui-ently, uihui-ently, he paid bjt v'jie attention, would ni:u- day aor chr bafla for ii revolutionary st-n in tfte progn of livHiaation. lie cbiii-el one day t seal i metal iplate Within the bOlU pi un incandescent incandes-cent lamp. He connected r. batterv , between the heated filament bf iho lamp and th metal plate. Th"n he found that when the positive posi-tive terminal of the battory was con-, i Led to the metal plate n current would actually flow between the plat! and the filament through the vacuum When the iiu-rv wai reversed no; r-.it-rcnt tvoul.1 flow. Mils was to him a strange phenomenon. phenom-enon. The cohtirlrance possessed what is kriuwn BS "unilateral conductivity " I . feJ 3 Hook-1 p Of 1 irsl Vacuum Tuli'- D.-- tootor. Some years later while ;-ffort was Jielng made to hit upon an efficient detector or rectifier of the high frequency fre-quency oscillations used In radio communication. com-munication. Professor J. A. Fleming, an Englishman, first made use of Edison's Ed-ison's conducting lamp for this purpose. pur-pose. This first vacuum detector was far !, aa Sensitive than our present day I three-element vacuum tubes, but the, combination of the rectifying action of this earlier too.- with the "trigger" action of out present day vacuum tubes aerVed as an Introduction to the vacuum ivjuo era of radio communication. communi-cation. Yai mm tu methods are now ro-pJoi ro-pJoi Ing all others for the creation, detection de-tection and amplification of the electrical elec-trical currents u-ed for radio signalling. signal-ling. The method of connection of the two-element or i'leming Vacuum lube detector Is shown In tho figure I iiuith-l !' Tho plate of the tube is connected to one terminal of the "tuner." The filament ehreuli i the detector tube Is connected throt'.Kh ihe telephone recolvers to the other tuner terminal Shunted across the battery used for lighting the filament of the lamp Is a resistance of 300 ohms which has rid-1 Ing upon it a cslldlng contact Changing the position-or the slid-, Ing contact gives a change of the voltage, volt-age, or potential.- which Is applied to the plate. Thus the Mow of current through the vacuum of the tube may be rfjruiated. When the potential applied 'to the plate has been properly adjusted, very small addKlon.il potentials produced by incoming slfinaln In the tuner will, cause a correspondingly great change of current flow between plate and filament fil-ament through the telephone recelv- j era. The flow of current' betwce.i plat and filament is known as the ' elec-' tron stream" The introduction of ii third elecenl Into present day vac-' uum ;ubr provider, more complete control Of this stream oo