cyclopticgaze

Lighting a Keyboard in an Under-mounted Drawer

Mar 5, 2006

     I like desks that have under-mounted drawers for your desktop computer's keyboard because it opens up valuable desk space (that can be used for piling more junk).  One of the things that I don't like about keyboard drawers, though, is that they obscure the keys in darkness as the sun goes down and your room gets dark.  I like having a dark room because the computer's monitor doesn't reflect a glare, and it makes playing games more dramatic.  And, while I can touch-type, I'm far from perfect at it.  It's always annoyed me having to look down from the monitor at the keyboard and then have to squint to see the letters on the keys.  Well, I certainly wasn't about to spring for an illuminated keyboard, so I whipped up a simple battery-driven LED circuit that mounts to the underside of the desk and shines onto the keys of my keyboard.

The keyboard in question, lurking in its dark drawer.  (Clickable images pop.)

     The first thing I needed was something to house a battery and mount a switch onto.  The choice was clear:  an Altoids tin.  Ok, so it's a Ginger Altoids tin, but it's got that same small form factor as a normal Altoids tin.  Here, I've drilled a hole and mounted a toggle switch, and drilled another hole for wiring to pass through.

The hole on the left, the switch on the right.

     Now the nitty gritty:  working out the wiring.  I'm keeping the circuit simple because all I'm going off of is some intro-level college physics courses and whatever Google will throw at me when I have a question.  I chose to use a 9 V battery because they're small and readily available (read:  cheaper than some exotic battery).  A quick trip to Radio Shack got me the switch above, as well as some el-cheapo red LEDs, a 9 V connector, and a bag of resistors.  The LEDs are rated at ~2 V, so I can use three on a 9 V battery (allowing at least 2 V for the resistor).  The LEDs are rated to ~20 mA, so I needed a 150 Ohm resistor.  Using good 'ol Ohm's Law:  (9 V battery - 6 V LEDs) / (0.02 A) = 150 Ohm.  I rounded up and bought some 180 Ohm 0.5 W resistors.

     Time to bust out the soldering iron!  I lined up the LEDs plus-to-minus, bent their leads, and soldered them together in a straight line.  After that, I soldered a wire onto the endmost LED's terminal and wrapped that connection in heat-shrink tubing.  This insulates that lead so I can bend it in line with the row of LEDs.  Some electrical tape at the solder joints binds the two wires together in a straight line and strengthens the whole thing.  Here's the project thus far:

     LEDs don't shine in all directians, so I purposely didn't mount or house the LEDs onto anything.  This will let me direct ther light by bending the leads after I've mounted them under my desk.  Crude, but it works.  Now, let's wire up the switch to the LEDs and the battery.  It's a simple single-throw switch with only two leads.  The red lead from the battery connector gets soldered onto one post of the switch, then the red lead leading to the string of LEDs is soldered onto the other post.  Lastly, the black lead from the LED string is soldered to the battery connector's black lead.  Attach the battery, throw the switch, and . . .

It's Alive!

     Ok, so it works.  Stuff the battery into the Altoids tin, and now it's time to mount this baby under the desk.  Continuing with our theme of "crude but effective", I'm mounting the circuit using clear packing tape.  The "open" design of the LED string serves three purposes:  it's cheap, it's easy, and it's very low profile.  This means I can tape the LEDs right above the keyboard and they won't touch the keyboard or even my hands when I'm typing.  Here, I've taped the LEDs under the desk, in the keyboard drawer:

They don't hang as low when the LEDs are bent to direct the light.

     The long wire to the battery/switch housing was done so that I could mount that portion of the circuit elsewhere, outside the keyboard drawer.  Here, I've run the wire outside of the keyboard drawer and have taped the battery/switch housing under the desk in a place where it's still easily reachable.

Gravity is no match for my packing tape.

     Here you can see the whole shebang, taped under the desk and illuminating the keyboard.

     So, how well does it work?

     Photography makes it look rather dramatic, but the design works well.  It took some fiddling to bend the LEDs so that they shine onto the keyboard when the drawer is pulled out.  That 9 V should power the LEDs for quite a while, and--most importantly--I can now see the keys of the keyboard even when the room is dark and the screen goes black.

     Total cost:  about $20.  It would have been even less, but I had to buy some new spools of wire.  Total build time:  about 2 hours, not counting the trip to Radio Shack.  Naturally, building a second one would take about 20 minutes.  And next time?  I'll spring for some super-bright blue LEDs.