Excellent link ! Thank you.

 

The value of a crystal radio set is no power needed, with that said, how about this:

1 - a really well designed tank coil, capacitor, and loop antenna, that favorite 1N34A diode.
2 - a solar cell with super cap for storage
3 - RF Preamplifier FET
4 - 2 transistor audio amp

 

The value of a crystal radio set is no power needed.

Nah. I think the limitations are so great that it's only value is as a novelty (and education) . Heck, a transistor radio can be powered by lemons:

 

I have used a MPF102 FET for RF preamp, 1N34A detector and 2N3904 AF amplifier with good success.