Faraday For Fun: An Electronic Batteryless Dice

Step 3 Free Power: Use your Muscles...

This step describes the muscle powered voltage generator. The generator consists of a Perspex tube of 6 inch length and an outer diameter of 15 mm. The inner diameter is 12 mm. A groove of about 1 mm deep and 2 inches long is machined on the outer surface of the tube. This groove is wound with about 1500 turns with 30 SWG magnet wire. A set of three rare-earth cylindrical magnets are placed in the tube. The magnets are 10 mm in diameter and 10 mm in length. After inserting the magnets in the tube, the ends of the tube are sealed with circular pieces of bare PCB material and glued with a two part epoxy and with some shock absorbing pads inside (I used IC packaging foam).

Such a tube is available from McMaster (mcmaster.com), part number: 8532K15. Magnets can be bought from amazingmagnets.com. Part # D375D.