What do you do if the power is out but you need to charge your cellphone to make an emergency phone call (or play Angry Birds). Don't worry there are plenty of power sources all around you that you can tap into. One of them is phone line. Even when in a blackout, there is still electricity in the phone line. This is because the phone company has their own independent backup power system. All you need to tap this power is a simple voltage regulator. Here is how to set it up.