Ian, What I would do is get several old phone chargers. Lets say you have two phone chargers that puts out 6Vdc each. Take the positive from one and the negative from the other and check the remaining leads, which should equal 12Vdc. The power source doesnt have to be strickly old phone chargers, perhaps an old remote control car batter charger, etc. Oh yeah be sure to get a multimeter to check voltages!