This is how to make crystal radio part 3. In this video, a explanation of the variant of crystal radio is shown. This is two part radio. This radio has two wires, they are antenna and earthing wires. And between two of them there is a diode.
The diode is used as bridge between that two connection. The earphone is connected to the antenna wire and the earthing wire. Basically, This radio is not receiving from the radio station. This radio receive the signal from the near area.