The Encyclopedia Americana; A Library of Universal Knowledge Volume 26

The Encyclopedia Americana; A Library of Universal Knowledge Volume 26

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 edition. Excerpt: ...Amplifiers" (in Electrical World, p. 570, 22 March 1919), "to build a reliable and efficient amplifier of more than three stages at any one Detector and Two-Stage Amplifier.that the increase in audibility is according to the square of six per amplifier. Thus if one amplifier increases audibility six times, two amplifiers will increase it 36 times, and so on. It has been stated that by "the use of successive vacuum tube amplifications, energy increases of 10,000,000,000,000 times have been obtained and that a six stage amplifier permits the feeble energy derived from a telephone receiver when employed as a transmitter to light an ordinary tungsten lamp, or to produce a sparking potential of several thousand volts." The amplifying power of the vacuum tube is, however, not an instance in which something is seemingly obtained for nothing. In this respect it is not comparable to the microscope or telescope. Rather, as pointed out by Batsel, its amplifying effects are obtained in a manner analogous to the increase of power in a direct current generator due to an increase of current or potential in the field circuit of the machine, which in turn increases the density of the magnetc field in which the armature rotates. The increased power in the dynamo output is disproportionately greater than the increase of current in the field circuit and is supplied by drawing upon the mechanical energy that revolves the shaft of the dynamo. Analogously the batteries that supply the heat for the filament and the electric potential for the plate are drawn upon to supply the power developed by the vacuum tube. In the case of the direct current generator the power is controlled by the magnetic field; in the vacuum tube the output is...show more

Product details

  • Paperback | 788 pages
  • 189 x 246 x 40mm | 1,379g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236901738
  • 9781236901736