MB102 Black Breadboard Power Supply Breadboard power supply module compatible with 5 V 3.3 V. Input voltage: 6.512 V max. (DC) or USB power supply. Output voltage: 3.3V/5V selected by setting a jumper. Maximum output current: less than 700 mA max. Two Bus Rail independent control can switch over to 0 V 3.3 V 5 V. Size: 5.3 cm x 3.5 cm How to use Breadboard Power Supply Correctly.: There are two power supply ports on the board a DC port and a USB port. You can switch the output power voltage of both ports between 3.3V and 5V by the jumper cap. The USB port can supply only 5V. So if you use the USB port as power supply the jumper cap of the output port MUST be at 5V; or else there will be no power supply. !NOTE! This USB port is not to be powered by a USB cable from a computer or USB power supply. Should power be plugged in it will smoke the voltage regulator. This is a power output only! The DC input port uses a 5.5mm/2.1mm plug with a voltage ranging from 6.5V~12V. With a DC input the output ports could switch between 3.3V and 5V. Note:12V is the maximum voltage limit. If you use an ADDC adapter you're recommended to use 9V in case of unsteady voltage which may burn the board. You can buy an ACDC adapter with a 5.5mm/2.1mm plug and 9V or 12V power supply. Or a 9V battery holder or battery clip with a 5.5mm/2.1mm plug. Also you can DIY the battery holder yourself: buy a 5.5mm/2.1mm plug and connect it with any battery holder providing a voltage from 6.5 to 12V (e.g. 5 to 8 AA batteries.)