I had a friend contact me regarding helping him out with lights on his ATV. I don't get to work on powersports vehicles much but occasionally folks contact me when they have electrical issues. Here's a link to a wiring diagram for the vehicle (it's a late 80s TRX250R) http://www.trx250r.net/forum/attachment.php?attachmentid=320&d=1222835980 [Broken] My friend is wondering about hooking up different lights. After taking a look at this diagram I said, "OK seems like a pretty simple circuit; a single-phase coil with the chassis as the circuit common for the coil and loads", to which he replied "I don't know about that I just don't know much about these half-wave systems". I pointed out that the diagram doesn't contain a rectifier therefore it is not a half-wave; it's simply single-phase AC powering the lighting circuit. It would only be half-wave if I were to wire a diode in series with the output wire. He insisted that it is indeed half-wave, specifically "any stator that goes to ground is half-wave". This assertion to me seems insane; "ground" in this case is nothing more than a convenient circuit common (the engine and chassis). There's no way for something that's just a chunk of metal from an electrical standpoint to act as a rectifier. But he and a couple other guys that work in that field are all telling me "that's a half-wave system". So I called a couple certified Honda shops and they gave me the same line, "any stator that goes to ground is half-wave". One actually defined it as a "half-wave AC system". Now I feel I've entered the twilight zone. Isn't "half-wave AC" a contradiction in terms? The wave will certainly fluctuate, but by its very nature a half-wave output remains on one side of neutral. Plus there's no rectifier on this vehicle, or several others of the old batteryless system that I looked up. There's a regulator certainly but it's in parallel with the load; my guess is that it's simply a transistor or thyristor that "shorts" the two ends of the single-phase coil to each to control the AC voltage across the load. Anyway what started out as doing a quick favor for a buddy has now morphed into my exploring some old ATV and dirtbike systems. Apparently the wisdom in the motorsports industry is that if you connect one side of a stator to the chassis it becomes a half-wave system, but I just don't see how a piece of machined metal acts as a rectifying component. Am I missing something blindingly obvious here? It's hard for me to imagine that multiple professionals in the field are all giving me the same bad info, but at the same time it is what it is: bare metal's not a semiconductor.