This project started off with the notion of a plug-in power supply for breadboard use. Many companies already offer this kind of unit. Spark fun has 4 different versions, Adafruit offers one that's got 3.3V, 5V and adjustable outputs, but it does both power rails the same. I wanted one that could do different voltages on each power rail AND be able to be chained together. If you run multiple boards connected (like I do) then needing 2 or 3 breadboard PSU's each with its own wall wort adapter can get kind of messy and hectic. What if you could run 2, 3 or more breadboard power supplies from a SINGLE input source? And what if you could have each rail powered at a different voltage? Enter CAC's Chainable Breadboard Power Supply.
10/30/2012: Updated .brd and .sch files uploaded (V8.5 - 10/30/2012). Links at the bottom of the page.
The idea started off simple - a single board that would supply 3.3V, 5V and an adjustable output. It would need to be able to power both rails indepenently. It would also need to have the ability to chain multiple units together to power them all off of a single input supply.
Version 1 came together fairly quicky. I used SMD voltage regulatos and connector pins. Filtering caps are added to the input and each output. Voltages are selectable via the 2x3 headers with the manual voltage control adjusted via the center-mounted 10k potentiometer.
Version 2 added on/off switches for each power rail and changed the potentiometer to a more readily available version.
Version 2 was the first version I used EagleUp to render a board for. It's not 100% exact but it is close enough to visualize the idea.
Version 8.5 is the latest version (10/30/2012). I slightly resized the board and also changed all traces to 32mil width and relocated some components. I also added a 0.1" header as an auxilary input. This give 3 total options for inputs - barrel jack, 3.5mm screw terminals or 0.1" header. Click for a larger version.
Version 8.0 schematic - click for a full-size image.
I also made an EagleUp render of the version 8.5 board, although I haven't added the components yet. Click for a larger image.
Here's a bare PCB from version 8. There was a silkscreen error which has been corrected in version 8.5.
Here's an assembled version 8 PSU. All that's missing from here is the barrel jack and/or 3.5mm pitch screw terminals.
Here's a single PSU installed onto a breadboard. It vits perfectly.
Here's a pair of PSU's hooked together and installed onto a pair of breadboards that are also connected. Both boards can be powered from a single input supply. With this setup you can select which rails you want to have which voltage. This is especially useful for the more complicated projects that require 5V for some components and 3.3V for others.
As of right now I've had a set of version 8.0 boards made. I then updated the boards to the current version (8.5). The version 8.0 boards I have made work just fine and are available for purchase. Send me an email!
If you want to make your own you can get everything you need below except for a pair of 100uF 50V capacitors. Sparkfun only carries the 25V versions which are fine for the 5V and 3.3V outputs, but for a broader range of output from the adjustable a 50V is required. You can find the 50V 100uF capacitors from your local Radio Shack or other electronics retailer.
This page will be updated as updates come along. Stay tuned for the latest info! If you have any comments, ideas, questions or suggestions leave them in the comments below or drop us a line!
This project is OSHW with restrictions:
Chainable Breadboard PSU by ComputersAndCircuits is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
Based on a work at http://www.computersandcircuits.com/?q=c-bb-psu.
Permissions beyond the scope of this license may be available at http://www.computersandcircuits.com/?q=c-bb-psu.