He found an assembled Philmore “selective” radio kit. The simple kit had a coil, a germanium diode, and a crystal earphone. We were sad when [Michael] accidentally burned a part of the radio ...

We are used to microwave receivers requiring ... With nothing more complex than a germanium point-contact diode and an oscilloscope, you can quickly, easily, and cheaply resolve microwave signals ...

Semiconductor crystals were used in radio and radar receivers because ... accidentally discovered that a crystal of germanium -- a semiconductor which was not well understood at the time ...