The 12V AC Brick™ is designed to function properly with an input power of 11-13V AC. The Brick will not operate from a DC voltage. A 2.1mm P5 style connector is used for the power input. If the input voltage is a grounded system, the center pin of the P5 is the power connection and the barrel is the ground side. All ProSeries units are shipped with a 12V AC, 600mA floating power supply that eliminates any ground loops through the power supply connection.