Crystal diode

1874,1904 Crystal diode

The book of science

Tom Sharp

Karl Ferdinand Braun, Henry Harrison Chase Dunwoody, Greenleaf Whittier Pickard electromagnetism Crystal diode

Crystal diode

Cat’s-whisker detector

Crystal divination

I made a radio in high school with a germanium crystal diode, and, using our garage door as an antenna, listened to the local AM station with an ear-bud.

See also in The book of science:

Readings on wikipedia: