Phonograph

Phonograph, or record player, instrument for reproducing sound recorded mechanically as modulations in a spiral groove. It was invented by Thomas Edison (1877), whose first machine had a revolving grooved cylinder covered with tinfoil. Sound waves caused a diaphragm to vibrate, and a stylus on the diaphragm made indentations in the foil. These could then be made to vibrate another stylus attached to a reproducing diaphragm. Wax disks and cyclinders soon replaced tinfoil, then when metal master disks could be made by etching or electroplating, copies were mass-produced in rubber, wax, or plastic. The main parts of a phonograph are the turntable, to rotate the disk at constant angular velocity; the stylus, which tracks the groove and vibrates with its modulations; the pickup, or transducer, which converts these movements piezoelectrically or electromagnetically into electrical signals; the amplifier; and the loudspeaker.

See also: Edison, Thomas Alva.