Red, yellow, blue, black: what does the colour of a toroid tell you? Tap a colour to see the mix, its permeability, its frequency range and its uses. Then calculate the number of turns for a coil, with a winding diagram, the length of wire to cut and the resonating capacitance, or for a balun, a 4:1 unun or an EFHW 49:1 unun, including core heating. The tool also recommends the right mix for each band and identifies the mix of an unknown toroid from a single simple measurement.
