I'm attempting to build my own pm generator and am trying to calculate voltage output. I see the formula for voltage output is N = number of turns of a coil, A = area of the coil and M = rate of magnetic field change in Tesla's/sec. So V=NxAxM Ok I get most of that,but what is eluding me is how to calculate the area of the coil ? Does it mean the wire diameter x the length of wire used, or length x width of the coil (in the case of a square or rectangular coil) ? Thanks very much for any and all help. Watts up.