Detector
Telephone Receivers
Fixed Condenser
Tuning Device
FIG. 60.—Portable receiving set and case.
Other instruments such as a potentiometer, test buzzers, variometers, variable condensers, etc., complete the outfit and improve its selectivity and sensitiveness.
FIG. 61.—Complete receiving outfit.
The detector forms the most vital part of the receptor. In explaining its action it may be well to recall and enlarge upon the description already set forth on page 11, where it was explained that electromagnetic or as they are more commonly called when identified with wireless telegraphy, Hertzian waves have the power of exciting oscillations in any conductor upon which they impinge. Electrical oscillations, it will be remembered, are alternating currents of very high frequency. They are generated in the aerial of the receiving station by the action of the waves coming from the distant transmitting station. These currents are exceedingly feeble, too feeble in fact to operate any form of electrical apparatus except a telephone receiver, which is one of the most sensitive instruments in existence.