I have a couple old but functional dynamo - One bottle, one roller. I'm
wondering if the electrical efficiency/efficacy can be improved by
rebuilding the dynamos. Has anyone have any experience with this? I
understand that i could potentially rewind the coils, replace the bearing
but how practical is this ... Before i attempt it on an otherwise
functional device. What else is practical to change; the magnet? More
poles? Any other interesting hacks or improvements?