One of my first electronics breadboards was a Radio Shack branded one which sits on a metal platform. At the time, I was using a DC bench power supply to power the circuits on the board. This is however inconvenient much of the time, as the DC bench-top power supply is a rather large device, and limits the breadboard to a close proximity of supply.
After awhile, I discovered some cheap breadboard power supplies, which supply both 3.3V and 5V to the power rails. The only problem was, they only fit on another popular style of breadboard, and I couldn’t find any that would fit a larger breadboard like the one I had. Because I liked the high quality feel of the larger platformed breadboard, I decided to make a power supply board for it.
The cheap power supplies for the smaller breadboards are relatively inexpensive, and easy to use. They fulfill most needs for controlling logic devices and other low power circuits. They basically can be powered by a DC barrel jack, and contain both 5 and 3.3 volt linear regulators, with a set of jumpers that can be used to individually select the desired rail voltage.
I decided that a similar design would also fulfill my requirements for the larger breadboard power supply, which a few exceptions. I decided to use a beefier power switch, and also include the option to use the input voltage right from the barrel jack input, this would give the user potentially three voltages to choose from. The 5v, 3.3v and 9-12v from the supply. Originally having a need for a 12v supply in one of my projects gave me this idea, and I figured the input supply voltage is already there, might as well take advantage of it.
The boards turned out pretty well, and I still to this day am using the Radio Shack branded breadboard and the Aliosensu power supply. I have also put this item up for sale at Tindie.com for anyone who has a larger breadboard, and needs a power supply for it.