This Usually ships within 1 to 3 weeks. -400 This design was inefficient due to self-cancelling counterflows of current in regions not under the influence of the magnetic field. While current was induced directly underneath the magnet, the current would circulate backwards in regions outside the influence of the magnetic field. This counterflow limits the power output to the pickup wires and induces waste heating of the copper disc. Later homopolar generators would solve this problem by using an array of magnets arranged around the disc perimeter to maintain a steady field effect in one current-flow direction. "build your own wind chimes " and "electricity generation from water " (include "home energy usage calculator", "home depot energy efficiency ", "home energy report scotland ", "history of solar powered cars ", "how to build a model windmill ", "Bike electricity generator ", 12 Jun 2011 Homemade Solar Cells - What You Need to Know About Homemade Solar Panels - Save money with homemade solar panels - Money saving tips on & Kids electrical projects )