jimbob jones said:
Im building a simple crystal reciever set. I am wondering if the diodes used in the detector stage have to be germanium diodes. And why is this?
Yes they do, because a germanium diode has a far lower voltage drop than a silicon one, a silicon one requires around 0.7V to conduct, a germanium one only requires something like 0.2/0.3V (going from VERY distant memory!).
If you'e doing it 'properly' you should use a lump of galena and a 'cats whisker', and NOT a germanium diode 8)
Have a look at for some examples.