Come to think of it, Michael Badger and I tried to make a crystal set when we were schoolboys. The set was a germanuim crystal or cats whisker as it was known. the wire came from Falconers radio shop. Just as a matter of interest, I served my time in Marconi and played in a group. Trying to save money I got one of the wiremen to make me a guitar effect using a circuit from Practical Radio. That night we were playing in a club and when I switched it on, all the audience heard was " Car 4 where pick up at labour club ". He forgot to use screened cable and it worked like a receiver ! What a laugh that caused!