Power Jack of the DS203 accepts "small" power connectors with 3.5mm diameter. Use ARP-P0011 , ARP-P0012 , or ARP-P0013 power adaptor supplied by Tibbo or similar adaptor. Acceptable power supply voltage range is 10-25VDC. Adaptor current rating should be at least 500mA. On the power jack, the ground is "on the outside", as shown on the figure below.