Hi
Yep, it is a pretty simple situation. There is a coil in the engine that produces about 16-18 VAC and the Reg just puts out a DC voltage to replenish the battery used for starting. These engines are used in lawntractors so not much else involved. No alternator like a car and no other fancy electronics.
I guess it should be better referred to as a battery charger but for mechanics, it is called the voltage regulator.
I just went back to look at the link I posted. I see it does refer to an alternator. That might be the incorrect part, although visually, it is identical. This engine only has the lighting coil so no field terminal on an alternator or anything like that.
Thanks
Cheers,