Crystal radio is the simplest type of radio receiver, and can be handmade with a few inexpensive parts, like an antenna wire, tuning coil of copper wire, crystal detector and earphones. It needs no battery or power source and runs on the power received from radio waves by a long wire antenna.
However if you hard to find a high impedance earphones or you want to listen crystal radio thru a speaker then this project could help you. Nina Gajjar has add some amplification for the very basic crystal radio schematic with an Op-Amp (TL-081) to increase level of crystal signal, so a low impedance earphones may be used and an audio amplifier IC (LM386) was added to drive a small speaker. For this modification, the project needs battery 9 volt as power source for the ICs. Download crystal radio with external speaker schematic.