Radio, miracle of the 20th century ... a story of human achievement that stands unrivalled in the history of humanity, together with a colorful portrayal, giving a broad, general view of the whole subject of wireless telegraph and telephone and its marvelous development (1922)
Drinker, Frederick E. [from old catalog], Lewis, James G., [from old catalog] joint author · [Philadelphia, Printed by National publishing co.] · leaf 231
would respond, would be inaudible, since the earwill not record frequencies much above 15,000 cycles.The problem now is to reduce the frequency used in radioto one audible in the telephone receivers. This is done inthe detector. This instrument groups together a numberof the cycles of high… … Fig. 5. (sulphide of lead) and a contact point of fine wire. Onetype is shown in Figure 5. When the wire is lightly brought into contact with thesurface of the galena the signal received by the antennaeis changed from alternating current to direct current in aseries of pulsations that act on the…
Radio
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