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| Keywords: Poulsen's first arc converter.jpg arc converter Poulsen arc radio transmitter built by US electrical engineer Valdamar Poulsen in 1903 One of the first continuous wave radio transmitters it was used in the first AM broadcasting stations until the early 1920s when it was superseded by vacuum tube transmitters It consists of a DC electric arc in a chamber filled with either hydrogen or other hydrocarbon gas center between the poles of an electromagnet horizontal cylinders front and back The anode right is water-cooled the cathode is made of carbon and is rotated continuously mechanism rear The arc is connected to a series resonant circuit not shown consisting of a capacitor and inductor which in turn is connected to a wire antenna The negative resistance of the arc cancels the positive resistance inherent in the resonant circuit exciting continuous sinusoidal oscillating currents in the resonant circuit which are radiated by the antenna as radio waves The arc oscillator was actually invented by Elihu Thomson in 1892 but the frequency of his device was limited to about 10 kHz By operating it in a hydrogen atmosphere with a cooled anode Poulsen was able to raise the frequency into the longwave radio range so it could be used for a radio transmitter 1904 Retrieved September 22 2013 from http //www earlyradiohistory us/1904pou htm Originally published in https //books google com/books id NI8LAQAAIAAJ pg PA971 V Poulsen System for producing continuous electric oscillations in Transactions of the International Electrical Congress St Louis 1904 Vol 2 Section C Electrochemistry J B Lyon Co 1905 fig 7 facing p 970 on Google Books Valdamar Poulsen Poulsen died in 1942 more than 70 years ago other versions PD-old-70-1923 Uploaded with UploadWizard Poulsen arc transmitters ImageNote 1 176 325 135 121 530 587 2 Arc chamber containing hydrogen gas ImageNoteEnd 1 ImageNote 2 119 367 115 102 530 587 2 Electromagnet ImageNoteEnd 2 ImageNote 3 282 388 150 47 530 587 2 Water-cooled copper anode ImageNoteEnd 3 ImageNote 4 51 285 142 80 530 587 2 Worm gear to rotate carbon cathode ImageNoteEnd 4 ImageNote 5 228 2 42 156 530 587 2 Gas supply pipe ImageNoteEnd 5 ImageNote 6 215 432 207 98 530 587 2 Rack and pinion to move anode forward ImageNoteEnd 6 | ||||
