Editing Rectifier (section)

==== Crystal detector ====
{{Main|Crystal detector}}
[[File:CatWhisker.jpg|thumb|Galena cat's whisker [[crystal detector]]]]

The [[crystal detector]], the earliest type of [[semiconductor diode]], was used as a [[detector]] in some of the earliest [[radio receiver]]s, called [[crystal radio]]s, to rectify the radio [[carrier wave]] and extract the [[modulation]] which produced the sound in the earphones.   Invented by [[Jagadish Chandra Bose]] and [[Greenleaf Whittier Pickard|G. W. Pickard]] around 1902, it was a significant improvement over earlier detectors such as the [[coherer]].  One popular type of crystal detector, often called a ''cat's whisker detector'', consists of a crystal of some [[semiconducting]] [[mineral]], usually [[galena]] (lead sulfide), with a light springy wire touching its surface. Its fragility and limited current capability made it unsuitable for power supply applications. It was used widely in radios until the 1920s when [[vacuum tube]]s replaced it.  In the 1930s, researchers [[Diode#Solid-state diodes|miniaturized and improved]] the crystal detector for use at microwave frequencies, developing the first semiconductor diodes.
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