I'm surprised nobody has made a wind-up cell phone. Besides not
requiring a battery or charger (uses a super-capacitor), it will keep
the chronic talkers in line. Not exactly energy scavenging, but (in
my opinion) just as good.

I have a hand-crank radio/flashlight/charger that can charge cell phones.
The problem with building it into the phone iteself is that it's "too big"
for such a small device.


Incidentally, I designed, prototyped, but never produced a paper tape
printing pager in the early 1970's. The pager ran on batteries, but
the 1/4" paper tape transport and printing was all wind-up mechanical.
I also proposed a wind-up portable floppy disk drive in the 1980's,
which was summarily rejected by literally everyone as a lousy idea.
Oh, well.

As the drive would have to be connected to computer that could power it, and
the wind-up mechanism + interface would be more complex than a motor -- what
would be the point?