On 24/10/2012 16:51, Tim+ wrote:
Martin Brown wrote:
On 24/10/2012 15:31, misterroy wrote:

I have stepper motors in the room and am about to look into using them.
thanks

Stepper motor on a small pulley, toothed belt/elastic band and a large
driven pulley one with a handle and you are in business. Also educates
them how much work it would be to light a even an LED by hand!

That reminds me of an awful display at our local windfarm visitor centre.
(Whitelees). There's a hand cranked bicycle wheel that lights up a number
of halogen capsule bulbs (about 60W each at a guess).

When spinning fast (for virtually no effort), you can light up 4 or 5 of
these bulbs. What's that supposed to teach?

Idiots designed the display.

It is incredibly educational to have a fixed bicycle/excercise bike and
a dynamo rigged so that it can drive either no load, a fluorescent,
small radio or an equivalent brightness incandescent lamp. A 100W lamp
is a fair amount of effort to sustain for any length of time. You can
keep it all low voltage by appropriate choices of component.

Did it once for an Xmas lecture. Also the hand powered one with an LED.
Kids switched unused lights off for at least a fortnight afterwards!

--
Regards,
Martin Brown