We
have generators in all sizes from toddler
to pre-teen, using various motors from car
radiator fans and computer printers. Displays have a large voltmeter
and a line of torch bulbs which light up progressively the harder they
pedal. Applications include music keyboards and Nintendo Gameboys
with no battery storage so that they shut down as soon as pedalling stops.
More visual stuff includes inflatable binliner
and carrier bag monsters five or six metres
tall powered by old computer cooling fans stuck in buckets, and an attraction
for indoor events is a pedal powered plasma globe.
All the applications are connected using standard colour
coded plugs; the children soon learn to connect
them up themselves which is quite safe. No fuses are needed as the generators
can't produce enough current to burn out wires. The voltage produced depends
on the speed at which it is pedalled but even if the children get off and
turn the pedals very fast by hand it is impossible to make more than about
20 Volts which is too low to give a shock. The moving parts are guarded,
the generators are supervised at all times and put away when out of use.
The generators themselves give a good practical understanding of electrical energy, but for school sessions we can add in more educational items such as the Watt Box which shows how big a Watt is in terms of heat, filament or LED light, mechanical energy, and sound.