I can solder, but I'm not really knowledgeable enough to design a circuit from scratch. I know I'd need regulated 5v power at 500mA. Almost every gadget I'd want to carry with me on tour can be charged from via a mini-b connector. My GPS, my cell phone, my Sony Mylo; they all have the ability to charge from a USB port. Hub dynamos seem to put out several times the power required for the job. Has anyone here tried something like this?