The crystal in a crystal radio was a rectifier (most often, these days, a germanium diode, which is, a type of crystal). The crystal in a crystal earpiece is a piezoelectric sound transducer.

Today’s question: Many years ago when I was about 10 years old I received the gift of a crystal radio. I think it had about three parts. What was the crystal and how did it work?

The crystal in a crystal radio was a rectifier (most often, these days, a germanium diode, which is, a type of crystal). The crystal in a crystal earpiece is a piezoelectric sound transducer.

This report describes the development of low-power balanced diode modulators suitable for amplitude modulation by television or sound signals of a carrier in the frequency range 10-1000 Mc/s.

Not having any money, and as not many jobs were available for kids, my only personal radio was a crystal set. I was introduced to electronics by my older brother Johnny. He was attending an ... One ...