An early type of radio. The first type of radio had only five components: an antenna that picked up the signal, a wire tuning coil with which the listener selected the station, an earphone to hear the broadcast, a ground wire to dissipate the electricity, and at the heart of the apparatus, a crystal detector that produced the audible signal. The crystal was a tiny chip of crystalline ore or stone such as galena. Generations of youths built the sets from scratch and spent hours hunched over the device to hear broadcasts from nearby stations. The reception range tended to be limited, so the introduction of diode tubes that increased reception marked the end of crystal sets' popularity.