Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Usually the easiest way to tell is if the brushes ever "swap" connections it will typically be DC. See the below diagrams which definitely do not include all possible generator types. But the point to make is that if a magnet moves toward a coil and then back away then it is probably AC if the wires path doesn't change. I am doing a horrible job of explaining that, but if the brushes go over one of these then it is prooooobably DC (Attachment Link) (Attachment Link)

Thank you but I was wondering how your can tell AC and DC output apart when you can't look inside the generator (some units are fully enclosed). Maybe by using an Ammeter?