Wiktionary
crystal sets
n. (plural of crystal set English)
Usage examples of "crystal sets".
All around the bed were more bookcase-crates, filled with paperbacks and old hardcover books, and on top of most of the crates were radios: clunky 1960 transistor radios, complicated receivers obviously made from kits, simple crystal sets, several Bakelite 1950s models, and even a huge Philco floor radio against the wall near the foot of the bed.
It looked just like one of those old-fashioned crystal sets, except that the crystal was very big, very shiny, and was set in a horizontal vacuum tube.
But you'll have it the most, because you'll be making more crystal sets for the village.