I had a crystal radio set. It had the one crystal, one long wire, one ferrite core to loop the end of the wire around for tuning, one small speaker, and one wir

I had a crystal radio set. It had the one crystal, one long wire, one ferrite core to loop the end of the wire around for tuning, one small speaker, and one wire for grounding. No electricity required. https://en.wikipedia.org/wiki/Crystal_radio https://en.wikipedia.org/wiki/Crystal_radio