pulling radio signals out of thin air as if by magic. Not all crystal sets take this slapdash approach, of course, and some, like this homebrew multiband crystal receiver, aim for a feature set ...

Crystal radios can feel magical, given their ability to tune in audio from distant stations with nothing but the energy from the radio signal itself. However, to achieve this feat, they typically ...

The earliest and cheapest radio set for the home was ... to a small piece of mineral crystal such as galena, which received and converted the signal to audio that can be listened to on headphones.