As great as theoretical explanations are, there’s a lot of value in watching the internals of a stepper motor move when its coils are activated in order. Also demonstrated are PWM-controlled ...

and decided to explore why wedge coils perform better than round coils in PCB motor designs. [atomic14]’s designs use four-layer PCBs which allow for more magnetic strength out of the coils made ...

F. R. HAIGH has recently compared the relative advantages of magneto and coil ignition used for generating the explosions which occur in motor-car engines (Students' Quart. J. Inst. Elec.