You see, a crystal radio doesn't need power because it merely recieves
radio signals. The buzzers would have to transmit information to the
host system, and hence would require transmitters. Transmitters
require power. Unless you're planning to somehow transduce the energy
from the buzzing motion (which probably wouldn't be enough to
communicate at RF), you need batteries.
J.p.
--- In quizbowl_at_yahoogroups.com, cooterchekov <no_reply_at_y...> wrote:
> Oh really? Ever build a crystal radio?
> http://home.gwu.edu/~ers/remotebuzzer.png
> Edmund
