DIY Dynamo USB Charger for a Bicycle | 自作の自転車用のダイナモ充電器(USB… | Flickr
voltage regulator - We're making a bike-powered USB charger and we have (almost) no idea what we're doing - Electrical Engineering Stack Exchange
SEWS Bicycle Dynamo Bicycle Chain Generator Charger with USB Charger for Universal Smart Mobile Cell Phone iPhone Bike Riding Eq|Electric Bicycle Accessories| - AliExpress