Seeing the makezine site reminded me of the newest iPod battery pack I added to the page. It was built by an artist/electronics geek who got a Masters at MIT and lives in New York City. People have been trying to come up with a good USB charger for the iPod for a while. A really primitive, but simple, setup uses a 9-volt battery and a voltage regulator to give the constant 5 volts required by USB devices. The problem is anything above 5 volts is wasted as heat, the thing stops working when the battery drops below 7 volts, and if you leave the battery connected it will charge all the way down even if it isn’t charging an iPod.
I’ve always thought it was sad, but not surprising, that all of the people doing these battery packs were guys. Apparently a woman’s touch was needed. Her pack uses a computer chip and an inductor to amplify the steadily declining voltage supplied by two AA batteries to exactly 5 volts with very little waste. It will supposedly provide a full charge to a video iPod giving an additional 2-3 hours of video so you can watch a long movie away from a computer or wall outlet. It doesn’t provide the oomph of my 8 AA Band Aids charger, but if you really wanted more charges you could just bring extra pairs of AA batteries. So that was impressive in itself.
But then she took it all to the next level, designing a custom circuit board so the whole thing could fit in an Altoids gum tin, thoroughly documenting the entire design and build process, and selling kits with all the needed parts as an electronics project for $19.50. I was so impressed I almost bought one even though I can’t solder worth a flip and my iPod doesn’t charge via USB.