. 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 . ve around each plate, and the plates are separatedby the mica rings. Figure 17-A shows this type of flange assists to keep the plates cool. Sometimes afan is used also for this purpose. This arrangement iscalled a quenched spark gap, and it has the property ofrecovering its nonconductance in a very short time, thati
. 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 . ve around each plate, and the plates are separatedby the mica rings. Figure 17-A shows this type of flange assists to keep the plates cool. Sometimes afan is used also for this purpose. This arrangement iscalled a quenched spark gap, and it has the property ofrecovering its nonconductance in a very short time, thatis, after only a few oscillations have passed. 250 BADIOTELEPHONY The other type is the rotating spark gap. Figure 17-Bshows the principle of such a spark gap. There is a ro-tating metal wheel carrying the metal projections a. Asthe projections approach the ends b of the circuit, theyget near enough for the spark to pass. The rotation ofthe wheel carries the projections past b and graduallymake the gap longer, so that it soon becomes too long tocarry the oscillations. Thus only a few oscillations arepermitted to pass. If the wheel is made to rotate at sucha speed that a approaches b each time the secondary ofthe changing circuit (A, fig. 15) reaches its high voltage,. the gap is said to be synchronized. If no provision ismade to obtain this, the gap is called a nonsynchronousgap. In practical operation the appearance and sound ofthe spark gap when the spark is passing tells much aboutthe operation of the set. Spark gaps are usually adjust-able. The spark should occur regularly (told by thesound) and should give bluish-white stringy sparks. Ayellowish color indicates an arc instead of a spark. If anarc is established in the gap, the efficiency of a set is muchreduced. A set works best when the longest gap givingregular sparking is used. As has been noted, an oscillation transformer transfersby electromagnetic induction oscillations from one circuit MIRACLE OF THE AGE 251 to anoth
Size: 2473px × 1011px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookidradiomiracle, bookyear1922
