I posted this up on the ocuk forums a while back and thought that you guys might like to have a looksee at it. In this tutorial I will be adding 16 Orange LEDs to a Xilence Red Wing 120mm case fan. So the fan in question, all basic and boring. I used several tools, bits and bobs. Some were required, some just to tidy things up. 16x Super Bright Orange 3mm LEDs. 4x 100 ohm resistor 1/4w Soldering Iron and thin solder. Scrap wire Thin. Insulation tape - Black Hot glue/glue gun (Cheapo off the bay) 12v Power Source Molex connector and a bit of wire (off an Antec Tri-Cool) Switch Drill, 3mm drill bit. Post-it Yellow Cable Ties Heatshrink Black A few pics of my equipment. Deciding which Resistor and shape of array. I always wanted to use Orange LEDs and built my design around this. An Orange LED has a typical voltage of 1.8-2.2v and a current draw of 20mA to 30mA (Max). I can safely string up to 5 in a line as the max voltage would only be 11v, which is fine in a 12v application. I could possibly do 6 but they might be underbright, only getting a max of 2v each. Using V = I R transposed to R = V/I because we know Volts and Current and wish to determine resistance. Our voltage is 12v-(2.2 x 4) because of the 4 LEDs in series. This gives is a required voltage drop of 3.2v. We know the current is 20-30mA, so I picked 25mA. Now the formula R= Gives me R = 128 ohm I dropped it down to 100, because I had some available and I fancied them just a little bit brighter. Measuring up and deciding where to put the holes. My fan is 119mm in diameter and therefore has a circumference of 374mm I wish to place 16 LEDs so worked out that the pitch between LEDs is 23.375 I drew equally spaced crossed on a post-it so that my holes would be more or less perfect. I made a small hole at the crosses and used a felt tip marker to make a mark on the fan. A hole punch would also work. [IMG]http://i959.photobucket.com/albums/ae72/Tealc_wii/Sums.jpg Drilling I am using 3mm LEDs so chose a 3mm drill. I purposefully offset the angle of the drill by about 15-20 degrees for added effect. Here's the holes all nicely drilled. I needed to clean up some burrs on the internal side of the fan with my fingernail. Biters, use a knife blade or something Install some LEDs just to see how they fit. Nice. So now we are ready to start loading in LEDs and soldering up. I kept the same convention, always placing the LED in with Anode to the left and Cathode to the right. The first LED needed a bend or two on the Anode to receive the positive wire and cut on the Cathode because the leg was too long. The second LED needed both legs cut. I bent the legs directly out of the housing so at not to encroach upon the surround of the fan too much. Added the next two LEDs, forming the Cathode of the fourth on to receive the future ground wire. It was particularly happy as the rigidity of the legs allowed me to ensure that the LEDs pointed where I wanted and it also made it much easier to solder them in place. So easy to solder, just applying some heat to the joint and pushing some solder into the joint. The tight fit of the LEDs in the holes held them in place beautifully. Then adding the resistor the Anode on LED one. LED branch removed from fan. Testing one string of 4 LEDs. Hooking up to my 12v power source and spinning the fan manually. Adding a bit of hot glue to hold them in place. Some LEDs needed holding away from the fan while the glue cooled. I found the 3mm LEDs just a tad long through this particular frame. Repeat the same process so that you have 4 individual strings of 4 LEDs on each side of the fan. Wiring up the common Positive and Ground wires. We must provide 12v goodness to all resistors so that each string of LEDs can receive the proper amount of voltage. I used the thinnest insulated wire I could find, some telephone installation wire that I had kicking about. I removed the black and red from the insulation. Wiring a red wire from the unattached side of the resistor to the one on the next side in a clockwise rotation. I started this at the wire inlet for the fan's standard wiring so that it can be bundled up in the same place. Then repeating the process with a black wire, starting on the negative side to the left of the standard wiring and moving counter clockwise from final cathode to final cathode Do not join the red back up with itself, only 3 sides needed to be spanned. Then adding a couple of wires for external power. I run out of thicker red wire so used blue wire. I hot glued the wires onto the fan here as the solder joints aren't particularly strong. A cable tie gathers things. Wiring in a switch I can't imagine ever wanting to turn this off but I thought I'd wire in the capability anyway. Here's my switch. It's a '1 off 2' type switch so one side will be unused. I may use a different switch later. The 12v source is wired to the centre pin, the LED array to the top/bottom post as desired. Wiring up to a Molex for Power I could have patched the wires directly into the existing fan wiring after the switch but I like to have separation with things like this, it also allows me to route the cables to a different location if needed. Donor Molex, a chopped power Molex for an Antec Tri-cool which now runs off my fan controller using a 3 pin fan header. Soldering the wires to the Molex, with heatshrink on the wires before I join them. So we are all done. Looks awesome I think. The profile of the wiring on top of the fan could short out against a case. So added some tape to insulate the wiring from my case. And finally some other pictures. I'm extremely happy with the way this turned out and feel it is so much better than my first attempt at this type of mod, whether this is due to the increased number of LEDs (16 vs 12) or learned techniques or just that the Red Wing reflects Orange better than a Antec TC Black does. http://i959.photobucket.com/albums/ae72/Tealc_wii/OrangeLEDBlackfan.jpg Night shots (had to be done) And a couple of videos showing the fans and other LEDs I've added to the case.. In the daytime.. At night..