The 1151B1 power supply is a "desktop"; single output 48-volt Direct Current (DC), 20-watt power supply. The power supply can operate within a wide range of Alternating Current (AC) input voltages: 90 - 264 Volts Alternating Current (VAC), 47-63 Hz. The 1151B1 power unit has a green Light Emitting Diode (LED) that shows the unit has power on the PHONE jack, pins 7&8 when AC power is applied.