File: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 (14570129078).jpg

Identifier: radiomiracleof2000drin (find matches)
Title: 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
Year: 1922 (1920s)
Authors: Drinker, Frederick E. (from old catalog) Lewis, James G., (from old catalog) joint author
Subjects: Radio
Publisher: (Philadelphia, Printed by National publishing co.)
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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g may be an oatmeal box.Its construction is described in detail below. Crystal Detector (S, Fig. 3)—The construction of acrystal detector may be of very simple design and quitesatisfactory. The crystal, as it is ordinarily purchasedmay be unmounted or mounted in a little block of metal.For mechanical reasons the mounted type may be moresatisfactory, but that is of no great consequence. It isvery important, however, that a very good tested crystalbe used. It is probable also that a galena crystal will bemore satisfactory to the beginner. The crystal detector may be made up of a tested crystal,the wood screws, short piece of copper wire, a nail, set-screw type of binding post, and a wood knob or cork.The tested crystal is held in position on the wood base bybrass wood screws as shown at 1, Fig. 3. A bare copper MIRACLE OF THE AGE 157 wire may be wrapped tightly around the three brassscrews for contact. The assembling of the rest of thecrystal detector is quite clearly shown in Fig. 3.
Text Appearing After Image:
Phone (T, Fig. 3)—It is desirable to use a pair oftelephone receivers connected by a head band, usuallycalled a double telephone headset. The telephone re-ceivers may be any of the standard commercial makeshaving a resistance of between 2,000 and 3,000 ohms, 158 RADIOTELEPHONY The double telephone receivers will cost more than allthe other parts of the station combined, bnt it is desirableto get them, especially if one plans to improve his re-ceiving set later. If one does not care to invest in a set ofdouble telephone receivers, a single telephone receiverwith a head band may be used; it gives results somewhatless satisfactory. Accessories—Under the heading of accessory equip-ment may be listed binding posts, switch arms, switchcontacts, test buzzer, dry battery, and boards on whichto mount the complete apparatus. The binding posts,switch arms, and switch contacts may all be purchasedfrom dealers who handle such goods, or they may bequite readily improvised at home. There is noth

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