Breadboard Power Supply Schema
There is a green LED to indicate the presence of power, and an ON / OFF latching switch to control the power to the board. On this particular model and version, the centre pin of the barrel socket is positive.
the input voltage through the barrel socket must be between 6.5 V and 12 V. Hence, if you wish to use it to its maximum capability you will need to remain in that range. This is a non-adjustable fixed power supply model, which is good enough for most applications. The manual states maximum output current to be 700 mA. However, it is probably better to use much lower voltages and current to be on the safe side in case you make a mistake on your breadboard circuit.
Jumper pins are utilised for selecting the voltage levels on each side of the breadboard power rails. You can choose between 5 V, OFF, and 3.3 V. There are two sets of jumper selectors for each side of the breadboard power rails; hence, you can have any combination of voltages on either rail. There are also header pins for tapping off voltages, using a cable or jumper wires.
Please note that input voltage is supplied by the barrel jack and the USB socket is output voltage.