On Mon, 16 Jan 2012 22:12:18 +0000, Graham. wrote:

Interesting that the transmitter works without batteries by
"harvesting energy". I wouldn't have expected it to work.

Well you don't need much for a short duration few mW pulse of RF...

Looking at the site mentioned they have motion (switch operation or
waggle it about/vibration) for power generation. I have a "shaker
torch", powerful magnet slides back and forth through a coil of wire.
Just letting the magnet drop through the coil makes the LED flash.

I like the peltier thermal stuff, there are temperature gradients all
over the place. Light switch, warm room air one side, cold wall the
other. Handheld remote, warm hand, cold innards.

--
Cheers
Dave.