Wireless Telegraphy and Telephony
Forfatter: Alfred P. Morgan
År: 1917
Forlag: The Norman W. Henley Publishing Company
Sted: New York
Udgave: Third Edition, Fully Illustrated
Sider: 33
UDK: 621.396.1 Mor
A practical Treatise on Wireless Telegraphy and Telephony, giving Complete and Detailed Explanations of the Theory and Practice of Modern Radio Apparatus and its Present Day Applications, together with a chapter on the possibilities of its Future Development
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66
WIRELESS TELEGRAPHY
readily pass through the coils of the telephone receivers,
but a path is provided through the condenser. The de-
tector rectifies the alternating current into a direct current
which the condenser opposes and forces to pass through
the telephone receiver and produce sounds.
When a battery is used in connection with a detector a
condenser is also necessary to oppose the direct current of
Fig. 82.—Interior of rotary variable condenser showing construction.
the battery and prevent it from flowing around through the
tuning coil instead of through the detector. The capacity
of the condenser may be smaller if the resistance of the
telephone receiver is very great for the reason that as the
wire grows smaller it offers greater impedance to the cur-
rent. The opposite also holds true and condensers of large
capacity are better fitted for use with telephone receivers
of low resistance.
Variable condensers are divided into two general types,
the “rotary” and the “sliding” plate, accordingly as the
plates forming the condenser are adjusted with a rotary
or a sliding motion. The rotary type consists of a number
of movable semi-circular aluminum plates which swing