I have been researching generators lately, whilst contemplating building my own wind powered generator. I think I understand the general layout: a central magnetic core that rotates with an outside ring of conductive coils spun in specific alternating turns with their own magnetic cores. If I am wrong please correct me, the best general description I could find for building one was: http://www.otherpower.com/woodmill.html I still have a few questions and appreciate any help that can be given. I understand that the number of turns of the coil effects the voltage output. I was wondering if there is a simple way to calculate the number of turns of the wire without sitting down and manually trial/error testing turns. I found a few sites, but they gave me different explanations yielding different answers. As far as the magnetic cores of the coils go, does it matter how the poles of these cores are arranged? Or does it just matter that it they be magnetic? What is the best material to hold the actual rotating magnet with. In the website above they use wood, but this is just a simple homemade solution. Wouldn't some sort of light metallic core be better? Would it take a relatively large generator to create ~20 amps at 12V? I know that engineers hate this kind of question, but as far as generators go am I looking at a smaller one that can be powered by wind, or am I looking at something that has to use a gas motor? Obviously I am no engineer, but just a guy that likes to tinker with things. If something that I say sounds ridiculous please correct my ignorance. All help is greatly appreciated.