Maybe you want to take your design and project mobile, for instance, up in the mountains away from your vehicle and any plug in outlets. It might be useful to have a battery powered device whose batteries you never change, but just crank up once a week. Or better yet, maybe you want to take your Arduino to the coffee shop and not have to look for an outlet or USB connection. Well, here's a quick little way to power your development board from a battery that never (well, you know) runs out.
I've taken a hand-crank-powered flashlight and hax0red it to power my AVR and Arduino development boards. The battery lasts for a good long time and if you crank it a few times before you use it you'll find you'll get a solid 3.5V out of it (depending on your battery). Plenty enough to power an AVR ATtiny, ATmega, and ATxmega, as well as other 3.3V devices like the STM32F ARM MCU indefinitely!
Step 1: Necessary Items
To make this work, you'll need either:
- DC motor (I've tried about 3 or 4 different kinds of DC motors for this and I got them all out of old CD/DVD players so you don't have to pay for one if you cannibalize).
- small 3.3 or whatever capacity battery (I've used several small lithiums for my testing)
- diode (a small 1N4148 will do)
- something to make a crank with (rod & hot glue, rubber band, etc)
or you can buy a hand-cranked flashlight from ebay for a buck and change. This method is prefereable for a couple of reasons. First, the cranking mechanism is far superior to probably anything you're going to make and will really torque up when you crank it, delivering energy to the battery and straight on through to the powered device. Second, you'll have a tiny motor and small battery already included for probably what you'd end up paying for the battery alone, so splurge and buy one or two (I bought two) hand-cranked flashlights. You'll be glad you did.
For both versions you'll need the standard tools: wire, wire snips, soldering iron, etc.