When it comes to power from sound, be warned that results are likely to be rather disappointing - there's a reason microphones and guitar pickups benefit from such highly sensitive pre-amps! If you're just looking to do it out of intellectual curiosity, though, then piezos will at least get you somewhere - like DC motors, they're a 'two-way' thing; put power in, get vibration (sound), put in vibration, get (a little) power. You can often scrounge them from old toys, too, so they might be worth a look.
Other than that, there are a few interesting projects out there looking at alternatives to turbines for generating wind energy - my favourite would have to be this one:
Cobbling one of those things together could make for an interesting and fairly cheap project - if you find the time to do it then I'd love to see the 'vital statistics' of how much juice it'll give you!
Thanks, that looks awesome. It's hard to find any good guides online (wikipedia links to one that makes no sense at all) but it seems like an easy project to do without instructions, since all it takes is a couple solenoids and a magnet or two.
Just experimenting with paper strips, it seems like the frequency depends on the width between the membrane and the base. Does anyone know if/why this is true?
Other than that, there are a few interesting projects out there looking at alternatives to turbines for generating wind energy - my favourite would have to be this one:
http://www.popularmechanics.com/technology/industry/4224763....
Cobbling one of those things together could make for an interesting and fairly cheap project - if you find the time to do it then I'd love to see the 'vital statistics' of how much juice it'll give you!