Abstract: A discoidal dynamo-electric machine has a discoidal stator carrying a number of meandering copper windings imbedded in a substrate having a magnetic permeability of less than 20 relative to air, and a discoidal rotor mounted on a central shaft so that the rotor can be positioned close to and rotates in a plane parallel to that of the stator. The rotor has a circular array of permanent magnets mounted on a backing plate of mild steel, each of the magnets having a trapezoidal or a truncated sector of a circle shape, the magnets being closely spaced around the rotor to provide a series of closely apposed and alternating permanent magnetic poles.