Originally inspired by the well-known Minty Boost, I wanted to make a combo headlight USB charger for my bike that I can easily remove. I live in Amsterdam, where it's not wise to leave anything remotely valuable on your bike. I also have a handlebar mount for my Galaxy S2 I got while in Tokyo (I love Akihabara). While riding a bike around Tokyo with a cached Google map of the area I had to stop and pick up a 4xAA phone charger to Navigate around all day. Since most bikes in Tokyo and Amsterdam have 6V bottle chargers on them, I thought a simple charger/headlight that you can easily put in your pocket would be nice to have. In Minty Boost tradition I put it in a Smint tin - the ones you get in Europe open at the top and are just big enough to house the small PCB and cables for USB and dynamo. I also added a 9V connector so I could run off a battery in a pinch. I decided to try using the 4805 low-dropout 5V linear regulator since it will operate at a lower voltage differential than the 7805 (~0.4V vs 2V). Originally I was just going to make a charger, but I thought it would be nice to have a headlight as well - having received a ticket for no headlight in Amsterdam before.