Maybe a stupid question: Would that work: create a small electric motor, mount one coil on the rotating wheel and mount another on the stand. Now put DC on fixed coil and AC would be generated on the other side (like in transformer)... Or will this not work? :-) (I am not an electrician.)

I know, I know - mechanical parts are not optimal - and also there are losses for electric motor - but the size is in question here...