Homemade crystal set radio receiver with headphones

Broadcast receiver. Generic crystal set, well finished in polished wooden box, with a pair of headphones, unknown maker, 1922.

The crystal set was a simple radio receiver which did not need any power to make it work. It only received AM, amplitude modulated, signals. The crystal, with a point contact, called a cats whisker as that was what was sometimes used, on its surface, created a diode action rectifying the carrier wave so making it possible to hear the audio signal which was modulated onto it.