I am a programmer but new to electronics and trying to combine voltage two DC voltages. This works when I use two separate batteries i.e. I can use two 9v batteries and connect them in series to get total of 18V power supply.
However when I try to do the same using the two 5V output from the power supply as in Solderless Breadboard with Power and I/O Breakout Board. It just stops working. What I did is connect positive from the 1st 5V output to negative of 2nd 5V output, and as soon as I do that the power supply stops working (may be it shorts). Can anyone tell what I am doing wrong? and if it is not possible then why?