Building the Generator

Your generator will consist of a coil held close to a spinning magnet. Cut out two cardboard discs roughly 3cm (1 in.) in diameter, and make a 4-5mm (about 3/16 in.) hole in the center of each. Insert the nail in the hole and push one disc up to its head. Cover the next 2-3cm (3/4 - 1 in.)of the nail's surface with a couple of layers of insulating tape.

Slide on the other disc until it butts up against the tape, and then wind more tape on the other side of it to fix it in position so that the cardboard discs are no more than 2-3cm (3/4 - 1 in.) apart. Unwind 30cm (12 in.) or so of wire from the reel to form a lead from the coil, and start winding the remaining wire around the insulating tape between the two cardboard discs. To keep track, it may help to make a tick mark on a piece of paper after every 100 turns. The number of turns is not critical, but the more the better; 1500 turns should do. Having covered the nail with a single layer of turns, continue building up layers one on top of the other. You don't have to do a particularly neat job.

After about 1500 turns, leave about 30cm of wire free at the other end and then cover the windings with insulating tape. Remove 1 cm (0.4 in.) or so of the insulation from the two end wires by scraping off the enamel, and connect them to the socket. Fit the bulb into the socket.

Pass the bolt through the hole drilled into the base of the magnet, and fasten it by tightening the nut. Fix the bolt into the chuck of a hand drill. Next, fix the sharp end of the nail in a vice (or between two heavy books) so that it's horizontal. Bring the magnet to within about 1mm (about 1/16 in.) of the nail head, which should be slightly off-center from the middle of the spinning magnet. Make sure the gap between the magnet and the nail head is as small as possible, but not so close that they touch. A tip here is to rest the hand holding the fixed part of the drill on the table-top so that it's as steady as possible.

Turn the drill handle as fast as you can and the bulb should light up. Generating electricity really is as simple as this!

Generators in cars and bicycles 

Major funding for Rough Science was provided by the National Science Foundation. Corporate funding was provided by Subaru.

Copyright © 2002 The Open University and WETA.