Original poster: "Mccauley, Daniel H by way of Terry Fritz <teslalist-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com> Anyone have the formula for capacitance of a toroid??? It seems every tesla cad program I have outputs a different value for the inputs I specify. I'm not sure which one I trust. So I'd rather do it manually. Thanks The Captain