Replace battery power with standard household current. 

Features:

• 300mA
• Input:110V/20V/AC
• 6 Output Voltages: 3, 4.5,6,7.5,9,12V DC
• 6 Adaptors:
  • 5.5mm x 2.5mm
  • 3.5mm x 1.35mm
  • 5.0mm x 2.10mm
  • 3.5mm
  • 5.5mm x 1.5mm
  • 3.0mm x 1.00mm
• Dual Polarity