Like a lot of other cable standards, Ethernet Cat5 has wires in it that are unused. With a little bit of DIY aptitude, you can commandeer these shiftless wires and put them to work, delivering power to devices on the other end of the cable. This technique is called Power Over Ethernet (or POE). This tutorial shows you how to do it. Be careful though. If you’re not careful, you can fry your components, or worse yet, YOU.
Hardware Beyond the Hype