I have always been interested in electronics and DIY projects since I was very young. So when I saw an instructables page for the Minty Boost battery-powered USB charger, I jumped on it. Small Altoids-tin based projects are nothing new. Many people have come to utilize the low cost and ease of modifying the Altoids case. There have been dozens of interpretations of an iPod charger. However, most utilize a low current, expensive 9 Volt battery. The Minty Boost has well-composed circuitry that uses 2 AA batteries which are cheap and plentiful while offering 3000mAh each as compared to the 500mAh for a single 9V battery.
The Minty Boost kit is a small DIY electronics kit that is meant to be assembled inside of an Altoids chewing gum case. The concept is simple. On long trips or with intense use, iPods and other battery-powered USB devices don't have the stamina we want. By keeping such an Altoids-tin charger handy, one can easily extend the battery-life of their USB devices by hours. On an iPod Video, you can amass 3 extra hours of power while using it on a Shuffle gets you 60 hours more. All this on cheap AA batteries is a blessing when power outlets are nowhere to be found.
The kit includes a pre-fabricated, high-quality printed circuit board that is sold by itself or with the electronic components. I opted for the complete kit with the PCB and parts so I wouldn't have to hunt down all the parts on Jameco or Digi-Key. The kit assumes you have some soldering skills, but even if you aren't handy with a soldering iron, the instructions are beginner-oriented.
The Minty Boost circuit board after I had assembled and soldered it.
Assembly was problem-free and went like most electronics kits: insert components keeping polarity in mind, solder, snip leads and test. As mentioned earlier, the Minty Boost uses 2 AA batteries to power the circuitry. The circuit takes the 3 Volts of the two batteries (2 x 1.5V) and runs it through a MOSFET-based boost chip. After the capacitors smooth the output voltage, the end result is 5 Volts at 100mA - USB spec.
The Minty Boost installed in the Altoids tin.
The next portion of assembly involves cutting a small section of the Altoids tin for the USB connector. Then comes fitting the PCB and battery holder. It was a rather tight fit and I spent a good deal of time fighting with the circuit board and cable. However, it finally found a snug fit, which is actually good so the board doesn't move when inserting or removing USB cables.
The final, working product. Actually, there were no batteries in when I took this picture, but you get the idea.
I haven't touched an electronics kit in a long time and the Minty Boost was a welcomed project. From opening the package to charging my iPod, only 20-30 minutes had passed. If you want to get more info on the specifics of the circuit and how it works, check out the amazingly detailed instructables page. The Minty Boost kit includes everything but the Altoids tin and runs for about 20. As for performance, the charger worked as promised on my iPod Nano. I might modify my charger a bit to add a small switch to the top of the case, as it is currently always on. However, the circuit probably doesn't draw much power at all when there is no load present. You can see some more pictures of the Minty Boost in this flickr photoset.