Carrying the wire spool, the winding ring rotates on a C-shaped fixture that brackets the toroid, which itself rotates under stepper motor control on a trio of rollers. An Arduino controls the ...

winding each of the three coils with about 400 turns of 26 AWG magnet wire. Also embedded in the stator are a trio of hall effect sensors to make the control via an Arduino and an L6234 motor ...