Friday, June 19, 2009

LED lighting for the computer desk

star light.jpgA few years back we made the mistake of replacing the ugly track lights in the house with halogen lights in the ceilings.

These lights are inefficient, don't last long and punch holes in the ceiling causing air to leak to and from the roof space.

Friend Gerald is studying energy efficiency and got me inspired to look at improved lighting for home.

This morning I went out after minimal research and purchased six of these Cree LED star light modules and a 700mA constant current power unit that takes a 12V rail (which I have here on hand) and regulates the current for the lights.

light bar.JPG


I screwed them all to an aluminium bar which helps to dissipate some heat and of course wired them in series.

computer light.jpgThey are blindingly bright to look directly at, but overall probably put out as much light as a 40W incandescent bulb. This unpleasant dazzling effect is no doubt because they are such point sources compared to a bulb, they really need a diffuser.

Judging by how hard my 1A meter bashed I'm guessing it's pulling about 1.5 to 2A at 12V so that's up to 24W. Just guessing.

The arrangement I've constructed places them behind my computer screen pointing up to the ceiling.

Overall the effect is quite pleasant and provides light around the computer screen with no glare. Here's how the ceiling looks.

ceiling light.jpg

These LEDs cost $20 each, not cheap, the power regulator was $25. Looking at the specs now, I see that I'm driving these LEDs beyond their rated current so I guess their life will be short. The aluminium bar is getting hot.

My guess is that about 20 of these devices would provide reasonable illumination for a work desk.

3 comments:

led lights said...

Great work on building your LED light bar, looks good! You could have probably saved yourself some work by purchasing a ready made one, and as you say, it sounds like you're a little short on thermal management! Like any solid state device, LEDs don't like to run hot. Computer chips have heat sinks to dissipate the heat and so do most LEDs. However, if you are using "low power" LEDs (indicator-light style) with low current, you don't need heat sinking. But for the type of LEDs you have, you'd be better off finding a way to get the heat out of the LEDs and into the air.

LED lights said...

I for one admire your get up and go. I am in the process of building a computer and I am sure I could buy a ready made one a lot cheaper. It is fun to do however and I have enjoyed researching all the different components.

Tom Smith said...

Nice post, I really appreciate your idea. On computer desk we just require small lights and the light which required less electricity. LED lighting is the best for fulfilling that purpose.