I wanted to add some custom lights to my computer using an RGB LED strip I had left over from a project. They are the Taotronics RGB LED 5050 Strip and I used the computer's Power Supply's Molex for +12V rail. I kept the microcontroller and remote that came with the strip but you could replace that with a fixed circuit or re-programmable microcontroller like Arduino.
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Step 1: Cut and Place Strips
I chose to place my strips along the window panel and wire them together using a telephone wire. Telephone cable is perfect for low voltage LED wiring because it has 4 wires. Use an x-acto to reveal the copper contacts beneath the insulation. Although the cable color doesnt matter, make sure to hookup 12V to 12V, R to R, G to G, and B to B. Set your soldering iron temperature as low as possible (but hot enough to melt solder) because you are working with thin gauge wire and copper pads. Use flux and tin the leads individually before joining the pad and wire for a quicker, neater connection. Make sure to leave one strip's end exposed so you can run a longer wire into the controller.
Step 2: Modifiying the Microcontroller and Adding Molex Power
I popped open the LED controller and desoldered the barrel jack and wires to the strip. I replaced the barrel jack with a molex connector. Molex connectors have ground signal in the middle two pins and +or-12V on the outer ones. The connector I had was from an extra fan and had connectors for +12V and GND. I soldered it in place of the power supply's barrel jack after I desoldered it. If you need help identifying which is ground and +12v, the ground plane on circuitboards is usually the largest surface area (to have minimum resistance and noise). You can also use a continuity checker on a multimeter or a simple circuit with an LED, resistor, and battery (leave two ends exposed and short the wires to light the LED).
I wanted to bypass the 4-pin male and female connectors that came with the strip so I soldered the wires from the LED strip directly into the controller. I used telephone wire again. Pay attention to the length of the wire you use so that it can fit nicely in your case. I chose to place mine in an extra hard drive bay in the front of the case so I gave the wire enough play to open the door and lay it flat.
Step 3: Testing the Soldering
Before plugging the strip into your computers power supply unit, test your work with a different power source. I used the 12V supply that came with the strip and used alligator clips on the removed barrel jack to interface.
Step 4: Insulate Connections
I used a hot glue gun to insulate the wires from touching and to hold them in place ( the strip's adhesives may stop working after the heat of soldering).
Step 5: Light It Up!
My controller had customizable colors so I programmed some oranges, purples, and blues to go with the cases orange theme. My favorite is the rainbow fade pattern though. There is a video of it on YouTube.
Step 6: After Thoughts.
After I completed this build, I found out there is a product that is ready made for plugging into your PC. Here is an example. If I didn't already have the extra strip for a previous project, I would consider purchasing this product. Although it costs more and is shorter, it is the convenience you are paying for. It was a fun experience soldering and spending some time inside my computer though. For more customization, add a re-programmable microcontroller with your own patterns (: Happy hacking!