crystal radio - HELP
The crystal radio receiver (also known as a crystal set) is a passive radio receiver consisting of a variable LC tuned circuit, a diode detector, and audio transducer. This is the original, and simplest type of radio receiver in existence. Such apparatus was in very wide use during the early history of radio and is still in limited use today.
Crystal sets with long wire antennas are still of interest to a small group of enthusiasts and a number of web sites are devoted to their construction. Regular contests are held pitting the performance of various designs against each other. Reportedly, modern solid state diodes, ultra-thin litz wire inductors, and low loss capacitors yield performance far in excess of the original receivers.