Battery powered USB chargers are pretty cheap at Amazon and other places, but as with everything else it’s always more fun to make your own. The basic concept of a USB charger is actually pretty simple, and you don’t really need more than a couple of very cheap components to make one yourself.

See the rest here: 
How to Build a 9v Battery Powered USB Charger

No related posts.

Related posts brought to you by Yet Another Related Posts Plugin.