. 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 . s no generatorbuilt capable of producing alternations of so high afrequency. Only a very few such machines are in useto-day and those only at the very high-powered stations. As has been shown, an inductance-capacity circuit willoscillate and it is in this way that the radio frequencyoscillations are secured. In order to get
. 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 . s no generatorbuilt capable of producing alternations of so high afrequency. Only a very few such machines are in useto-day and those only at the very high-powered stations. As has been shown, an inductance-capacity circuit willoscillate and it is in this way that the radio frequencyoscillations are secured. In order to get such a circuitto oscillate, it is only necessary to furnish it electricalenergy. This energy must be furnished, then the sourceof energy removed from the circuit, and the inductance 232 EADIOTELEPHONY and capacity thrown in series in the circuit. This isdone by the use of a spark gap. In figure 5, the source of high potential is charging thecondenser as shown in the diagram. The two terminals(electrodes) of the spark gap (they are usually metalplates) are also being charged as they are in electricalconnection with the source of potential. As the charginggoes on both the condenser and the electrodes of thespark gap rise to a higher and higher potential. When this potential reaches a certain high value it is strongenough to cause a spark to jump across the air gap of thespark gap. The instant this spark passes, the air gapchanges its electrical character. Instead of being a verygood insulator it becomes a fairly good conductor. Thecondenser and inductance therefore are thrown in seriesand oscillations take place in the circuit. The oscillations are confined to the condenser-spark-gap-inductance circuit, as the iron-core choke coil pre-vents their passage through that circuit. The choke coilhas a very high self-inductance, due to its iron core. The MIRACLE OF THE AGE 233 current of an oscillation changes very rapidly. As thisrapidly changing current attempts to enter the
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Keywords: ., bookcentury1900, bookdecade1920, bookidradiomiracle, bookyear1922
