Crystal radios were the first widely used type of radio receiver, and the main type used during the wireless telegraphy era. They were first used as a demodulator for radio communication reception in 1902 by G. Crystals were first used as a detector of radio waves in 1894 by Jagadish Chandra Bose, in his microwave optics experiments. The rectifying property of a contact between a mineral and a metal was discovered in 1874 by Karl Ferdinand Braun. Thus, crystal sets produce rather weak sound and must be listened to with sensitive earphones, and can receive stations only within a limited range of the transmitter. However they are passive receivers, while other radios use an amplifier powered by current from a battery or wall outlet to make the radio signal louder. This component is now called a diode.Ĭrystal radios are the simplest type of radio receiver and can be made with a few inexpensive parts, such as a wire for an antenna, a coil of wire, a capacitor, a crystal detector, and earphones (because a crystal set has insufficient power for a loudspeaker). It is named for its most important component, a crystal detector, originally made from a piece of crystalline mineral such as galena. It uses only the power of the received radio signal to produce sound, needing no external power. The antenna wire, right, has a clip to attach to metal objects such as a bedspring, which serve as an additional antenna to improve reception.Ī crystal radio receiver, also called a crystal set, is a simple radio receiver, popular in the early days of radio.
1970s-era Arrow crystal radio marketed to children.
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