You can hack some parts you probably have lying around into a cable that will let you power electronic projects from a PC.
I initially did this article on my web site at uC Hobby but figured I would give it a try as my first instructable. Let me know what you think.
First let me say that this is dangerous. Your PC power supply should have protection from shorts but you are sure to loose any open files not if, but when you make a mistake on your breadboard. Also the PC power supply can output a great deal of current so things can get out of hand quickly. In fact, the more I think about this, the more I realize it is a bad idea.
The first two pictures show the finished product. A PC power plug with long extension wires that reach my microcontroller breadboard. The PC provides +12 and +5 VDC.
Step 1: Find Parts
I scrounged an old PC fan for this hack. We can use the long red and black wires and the male power connector to make our cable. I dug up a long piece of yellow wire to extend the +12V.
Step 2: PC Power Connections
PC drive connectors have 4 connections, 1 Red = +5V, 2 Black = GND, 1 Yellow = +12V.
Step 3: Connect Extension Wires
Notice that the wires are cut at different lengths. This is an old trick; each wire is cut to prevent shorts. The red wire splice will be in a different place then the black or yellow connections. When you tape up the splices you can wrap around all the wires which is easier and ultimately safer then trying to protect each splice when they are all side by side.
Step 4: Solder the Connections
I wrapped the wires together then soldered each connection. The two black wires are ground and were wrapped together along with the black extension wire.
I like to strip a long section of the insulation, wrap, solder then trim about half the length. This makes it easy to ignore large solder blobs at the end of the connection. You don't need a 3/4 inch connection after it is soldered.
Step 5: Braid and Tape the Connections
All the connections are complete in this picture. Next I loosely braid the wires together then tape the connections as well as wrap some tape every 8 inches or so just to keep it all together.
Once you have taped up the cable, you can connect it to your PC. Remember that if you have any shorts your PC will instantly shut down. Any files you have open will likely be lost.