My first crystal radio was a Radiocraft Remco Crystal Radio kit, that was made in 1967. Sometimes to improve reception you can reverse crystal diode leads; or reverse the plug where the earphones connect.

The crystal radio uses no battery or electricity. It uses AM broadcast radio waves for energy; that is sent out by a radio station transmitter. I uses a long antenna that is about 50 feet long and mounted about 20 feet above the ground; that can make the radio waves strong enough to hear the AM radio stations, through a a headphone set. There is also a ground wire that is connected to the crystal radio.

The tuning coil is used to select different radio stations; that uses a rod and ball station selector. Thje crystal diode converts the radio wave energy to sound wave energy; that can be heard through a crystal radio headphone set

The Radiocraft kit is a simple circuit crystal radio.