Over the summer a couple of years ago, I started to use my (quite old) desktop to play some computer games. I was playing in the dark, and couldn’t see the keyboard to type anything, so I decided I wanted to make a keyboard light. I didn’t want to ruin the night vision I had gained from being in the dark, nor to distract from the game, so I decided I wanted the light to be red, or as close as possible. I went scrounging for LEDs I could salvage, but all I could really find was a hard drive mounting cage from a server that had orange surface mount LEDs (1206 I think).
The board I removed the LEDs from, it still has 2 green LEDs for each drive:
I removed all 6 orange LEDs, but since they were SMD, I couldn’t easily just solder wires directly to them, so I cut up a protoboard and soldered the LEDs to those pieces, and soldered the wires to that:
I then cut a long thin strip of cardboard and mounted the LEDs on that, equally spaced:
I wanted the LEDs to have a standalone power supply, but because most of the wall warts I have are unregulated and not switched mode, they can fluctuate voltage with current quite a bit. I was playing with lasers a bit at this point, and had an LM317 constant current driver (I think the design is attributed to someone called Daedal on laserpointerforums.com) that was good enough to drive a laser diode. Laser diodes are much more sensitive than LEDs, so it was overkill for the LEDs, I probably could’ve just used a resistor, but since I had it, I figured why not use it. The driver is fed right form a 12v wall wart (I think 300mA). Here’s a closer picture of the driver:
I have the lights on their own switch on my power strip, so I can control them independently from everything else and only have them on when I need them. Here’s what it looks like from a user’s point of view:
It works quite well; I use it whenever I use this computer in the dark.