Altoids LED Lamp.
I’ve been interested in LED lamps for some time now, and finally bought a batch of bright white LEDs. I got these from LED supply. The LEDs run at 4.5V max at 20 mA and have a luminous intensity of 6400 mcd. They aren’t the brightest LEDs I could find on the net, but they are brighter than most, and the price isn’t too bad, $13.50 plus shipping for 10 of them. In contrast, Radio Shack wants over $5 each for their bright white LEDs (at about half the luminosity). LED Supply shipped two days after I ordered, and I received them by priority mail the next day, about 72 hours after placing my order.

I had a chat over IM with my father last night about the LED lamps, and he made a couple suggestions that helped with the design. I was originally going to hack up my halogen desk lamp, but decided against that since I sometimes need the intense white light it provides, like when I was building this lamp. He suggested using household copper wire and wrapping the leads around it. I still think that’s a good idea, and may pursue it for my next light, but I ended up using some 20 guage wire, twisted tightly for the stalk and an Altoids tin for the base.


The Head
For the head I wanted the LEDs mounted in a line. It will also need to be light weight to be supported by the twisted 20 guage wires. I hacked up a premade circuit board from Radio Shack, cutting away all but the center two strips of traces.

(click the images for a larger view)


Start by scoring the circuit with a sharp knife. Keep running the knife through the cut until you’ve scratched a nice line the length of the circuit board, be sure to cut all the way to the edges. Use a pair of blunt nose pliers to gently crack along the scored line, be gently and go slow. Finish up with some sand paper to remove the excess material. Next time I’ll get the sand paper out sooner. In trying to nibble the rough edges off with a pair of cutters I managed to take a bit more than necessary.



You can see my bad solder joints above. I have some heat shrink tubing waiting to cover my embarassments. I imagine if I could solder well enough there wouldn’t be any need for the heat shrink.

I should have taken some pictures of twisting the wire. Maybe next time. Fold a good length of wire in half, grab the two cut ends with a pair of vice-grips, make a t-handle with a screwdriver at the loop end and twist. Twist it hard enough to sretch the wire, this will anneal it slightly and make it stiffer and better able to fend off the forces of gravity.



Time to add the LEDs. Be sure to watch their polarity. It’s critical that they all run the same way. The D in LED mean diode and they only allow current to pass one way. The longer lead indicates which side gets the positive voltage. I started out with 3 LEDs, but added a 4th to bump the light output.



The heat shrink tubing is in place. You can see the loop of the twisted wire in the background. I cut that off before stripping the wire and soldering it to the circuit board.

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