Transformer & Magnetic Circuit Designer

How this is built: a magnetic circuit solved exactly like an electrical one — reluctance in place of resistance, flux in place of current, magnetomotive force in place of voltage. Required turns come from Faraday's law (V = 4.44·f·N·B·Ae), rounded up to the nearest whole turn, which is why the actual peak flux density is always at or slightly under your target, never over. Series paths add reluctance directly; the gap and an optional shunt/concentrator combine as a parallel pair. The air gap includes a standard first-order fringing correction — flux bulges outward at the gap, enlarging its effective area beyond the core's own cross-section, so the gap's reluctance (and the "effective area" row below) is a little lower than a naive same-area calculation would give. That correction is only reliable for a gap that's small relative to the core's own cross-sectional width — a warning appears if your gap is large enough that this stops holding. Magnetizing current is treated as sinusoidal, valid well below saturation; real magnetizing current distorts as a core approaches Bsat. This is the analytical starting point real designs use before refining the geometry in a field solver (COMSOL, ANSYS Maxwell, etc.) — not a replacement for one.