Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com> I'm looking to create some ferrite core transformers(have cores)but I dont have the formulas for them. I use n = (E*10^8) / (4.44*f*A*b) for steel laminate transformers, is this acceptablle for ferrite transformers operating at high frequencies(like 100000 Hz). Thanks.