i decided to make a instructable on this since i couldn't find one when i needed it. This is a very simple DIY project. first of all your going to need a TIP 31 transistor, 12V power source, breadboard, wire, and L.E.D's. you don't need the breadboard necessarily i made my own PCB for this project. I've also included a very easy and cheap method of PCB etching.
Step 1: Gather Your Parts!
1 TIP31 Transistor
12 VDC Power source
If you are going to etch your PCB you're going to need some Ferric Chloride, all i could find was the etching solution they sell at Radioshack. PCB board, also purchased from Radioshack. A plastic container, latex gloves, and a sharpie Marker.
Step 2: Making the PCB
OK You're going to need the PCB board(copper clad board) from the last step. First you are going to wipe the coper down with alcohol and dry it off with a paper towel. Second you're going to draw your circuit path, for this we need the sharpie. we use the sharpie because it resist the ferric chloride. I used the Diagram shown below. After you've drawn your circuit path its time for etching. Make sure you wear your gloves at all times when dealing with the ferric chloride. First you need to find a plastic container or anything plastic about 3in. deep really. Pour just enough of the ferric chloride to cover your Copper clad or so that your copper clad is at least fully submerged. Once in the ferric chloride just shake it around a bit or as they would say agitate it, it helps speed the process up. Once you see that all the copper has been dissolved you may carefully remove the board and dry it off with paper towels. Lastly, to remove the sharpie you can wipe it of with rubbing alcohol or just scrub it with the paper towel its really just up to you. Prest, a clean looking PCB. If you are not using the PCB then just follow the wiring diagram shown below.
Step 3: Finished!
Thats all there is too it really. if you guys have any problems or anything let me know because this is my first Instructable.