"dave @ stejonda" wrote in
:

In message , geoff
smith writes
I have seen an advert for an L.E.D flashlight that is activated by
shaking it,there are no batteries.
How does it work ?


from http://www.generationgear.com/produc...echnology.html

"
It all started back in 1830 when the English physicist Michael Faraday
discovered that passing a magnet near a wire coil could induce an
electric current in the wire. This "Faraday Principle" forms the
foundation for all of today's electric motors, generators, &
transformers.

Generation Gear has taken this principle to the next level. We have
combined it with two advanced semiconductor devices to create a
flashlight that never needs batteries!

Shaking the ShakeLight will cause a magnet to slide back and forth
inside the flashlight handle. As it does so, it passes through a
copper coil, thereby inducing a current in the coil's wire. This
current is then stored inside an electronic component called a
capacitor which in turn provides power to the LED (Light Emitting
Diode). "


A local TV news consumer segment did a test on these LED lights and found
them to not be very useful,nor worth the money.They dim very quickly.

--
Jim Yanik
jyanik
at
kua.net