bisa juga pake dc t0 dc converter murah kok kalo nga mau pake batre ... adaptor nya 5v, contohnya
LM2596 DC-DC Step Down Voltage Regulator
(http://1.bp.blogspot.com/-F_XrI0CpOzI/ViPe1KG7MqI/AAAAAAAABgo/KQN_1lOgb4o/s1600/dctodc.jpg)
harga e sekitar 25 rebuan