 A foxhole radio is a simple crystal sets
radio receiver cobbled together from whatever parts one could make (which were very few indeed) or scrounged from junked equipment.Such a set typically used salvaged domestic wiring for an antenna, a double-edged safety-razor blade and pencil lead (or bent safety-pin) for a detector, and a tin can, magnet and some wire for an earpiece.Razor blades of the era were chemically coated ("blued") and this coating could function as a diode, in the same way that a galena-catwhisker detector operates.