The video above describes
what the advertising display industry calls a solar rocker motor.
It uses a tiny solar cell
that self starts the motion and keeps swinging till the light is taken
away.
I'm thinking this could
easily be adapted to a small AAA battery for night operations. The
company that sells them is currently out of stock and has no plans to
build any more in the future, but you might find one in a small store
moving some sort of advertisement back and forth. Offer the person
behind the counter 20 bucks and see if you can't negotiate a deal to
take it home for some back yard deer deterrent experiments of your own.
It's unclear if this is
strong enough to create a banging sound, but the movement is worthy of
more research.
