Desk lighting

[edc3]

I'd like to add some led lighting to the underside of the shelf above my computer desk. I had a cheap 5mm led light from Costco there, which was very dim and had horrible battery life. After doing some reading in this forum I've decided that I would like to do something similar to the under cabinet lights that some of you have made. I'm planning on using three Cree XR-E Q5s on stars, thermal epoxied to 1/8" aluminum flat bar, wired in series and powered at 350mA. The part I'm undecided on is how to power them. The options I've come up with are an AC wall wart with the appropriate resistors to supply the desired current, a wall wart and 350mA Buck Puck with external dimmer, or a Xitanium 350mA. It would be nice for the light to be dimmable, if there's a reasonably efficient way to do so. Any comments, suggestions or ideas? Thanks.

Don

 

[curby]

Heh, you're doing exactly what I'm doing. If dimming is optional I'd go with the Xitanium, as it's just simpler. I'm going for a Boostpuck with this PSU. By pushing the input voltage up, the efficiency of the Boostpuck goes up. The PSU efficiency is upwards of 84%, and that of the Boostpuck is upwards of 95%. If you can put the parts in their optimum ranges, you'll have ~80% efficiency, which is better than a lot of PSUs out there. I'm considering controlling it with an Arduino microcontroller powered off a USB hub. This will allow for shutting off power to the PSU via a relay to eliminate phantom power draws (except for the Arduino) when the power's off. But the simple thing to do is just use a potentiometer. =)

 

[edc3]

Hey Curby!

As a matter of fact, I've been following your workstation light thread. After some testing with a power supply and various resistors I decided that dimming would not be necessary. I got a good price on a Xitanium from the Shoppe and the project is (mostly) done. I'm still fiddling a bit with the placement of the light and thinking about possibly diffusing the LEDs. But for now it's functioning very nicely. Thanks for the info!

Don