In article ,
Bill Wright wrote:
My first guess would be an old bike 'dynamo' - the type that is
friction driven from the tyre wall.

Or a hub dynamo.

I'd say the type I mentioned easier to mount on something and drive with
an electric drill?

We are talking about a school teacher so need to keep things as simple as
possible. ;-)

--
*The problem with the gene pool is that there is no lifeguard *

Dave Plowman London SW
To e-mail, change noise into sound.