Step 1: Parts List
1. 5mm Red Blue Green Color Changing LED. You probably won't find these in your local electronics store. If you search on eBay for "5mm led rainbow rgb" you'll find them. They cost approximately $13 for 100.
2. Resistor: 82 ohms, 1/4 watt. Color bands: Gray-Red-Black.
3. USB cable with a male type A connector on one end.
4. Thin wire.
5. Heat Shrink Tubing (1/8" and 1/4" diameter) or Electrical Tape.
Light Base Parts
1. Copper pipe fitting with 1" and 1 3/4" ends.
2. #14 Cork (1" diameter on the small end and 1 1/4" diameter on the large end)
3. 1/2" Nut - (1/2" diameter center, 3/4" outer diameter)
1. Clear Quartz Crystal with bottom diameter no larger than 3/4" - I got mine for $10 at a gem shop in San Francisco.
1. Soldering iron and solder.
2. Wire cutters/strippers.
3. Heat gun or similar (optional) if you're using heat shrink tubing.
4. Small metal file.
6. Drill with a 1/4" drill bit.
7. Box cutter or X-Acto Knife
Step 2: Overview
The circuit for the light is equally simple as shown in the schematic on this page. The resistor is soldered to one lead of the LED (the "anode") and then soldered to the "positive" (red) wire in the USB cable. The other lead from the LED is soldered to the "negative" (black) wire in the USB cable. The color changing magic occurs inside the LED itself - no need for any external electronics.
Step 3: Prepare the LED for attachment to the USB cable
1. Look closely at the LED. You will notice that the wires (leads) coming out are of two different lengths. The longer lead is called the "anode". The shorter lead is called the "cathode".
2. Cut off about two thirds of the anode and about two thirds of one of the leads on the resistor. It doesn't matter which lead of the resistor you use.
3. Solder the anode to the short lead on the resistor as shown in the second image for this step. The soldering can be a little tricky at first and may take you a couple of times to do it. What I do is slightly bend the leads so that they lay flat on a surface. I melt some solder on the tip of the soldering iron and then gently touch it to the leads and lift the tip way. The wires will then be attached as shown in the image.
4. Next you need to cut a small piece of wire and strip off the end. You can use uninsulated wire if you want since you will be adding insulation in a later step. In a similar fashion to the previous step, cut of two thirds off the cathode and solder the wire to it as shown in the third image.
5. Cut the newly soldered wire to make it the same length as the anode/resistor and strip the end as shown in the last image in this step.
Step 4: Insulate the LED leads prior to attachment
1. Cut two pieces of 1/8" diameter heat shrink tubing so that each is almost the length of each of the leads. Leave enough room at the end for an upcoming step where the leads will be soldered to the USB cable.
2. Slide the heat shrink tubing on to each of the leads as shown in the second image.
3. Using a heat gun or other source of heat, apply heat to the tubing until it shrinks around the leads. When finished it should look like the third image. VERY IMPORTANT: As you do this step, make note of which lead has the resistor. You will need to know that in order to properly connect the leads to the USB power cable leads.
Alternatively, if you do not have or want to use heat shrink tubing, you can cut small pieces of electrical tape and carefully wrap them around the each of the leads to protect them from touching and shorting out.
Step 5: Prepare the USB cable and attach the LED
1. Inspect the USB cable. Make sure you have one with a male type A connector on one end. See the first image for this step if you are unsure whether you have the correct connector.
2. Cut the cable leaving a good length of cable between the male type A connector and the cut end. You will want a decent length so you have flexibility to place the light away from the device that's powering it.
3. Put the other end of the cable in your junk box: you will undoubtedly be able to use it in another instructables project.
4. Using a small sharp knife (box cutter or X-Acto knife), carefully remove about a 1/4" of the outer insulation from the USB cable. The easiest way to do this is to gently cut a line along the length of cable. At the end of the cut, cut into the insulation around the circumference of cable. Don't press too hard - as you press, you'll feel the inner wires - don't cut any deeper. After making these cuts, you should be able to peel away the insulation, revealing the shielding. This is shown in the second image for this step.
5. The shielding may be strands of bare wire or wire foil or a combination of both. Peel away the shielding and remove it with a knife or scissors.
6. You should now see four colored wires and possibly a wire with no insulation. If you see a bare wire, cut it off.
7. The two wires that matter for this project are red and black. These are the power wires. The other two wires are for data: you won't be doing anything with those - you can leave them as-is.
8. Strip a small length of the insulation off the red and black wires as shown in the third image for this step.
9. The order in which you do this part of the step is important. First, cut a small length of 1/4" heat shrink tubing and slide it over the cut wires and down onto the USB cable. Second, cut two small lengths of the 1/8" heat shrink tubing and slide them over the insulation on the LED leads. Don't make them too long - you don't want them too near the soldering iron when you're soldering or they will shrink and you may have to start again. This is shown in the fifth image.
10. Now solder the LED lead with the resistor to the red wire from the USB cable and solder the other lead to the black wire. It's very important to get this right.
11. Once soldered, slide the 1/8" inch heat shrink tubing over the bare metal where you soldered the leads together and apply heat to shrink the tubing. The result should look like the sixth image.
12. Now move the 1/4" heat shrink tubing over the unused wires and the newly insulated wires and apply heat. The result is a nice looking, fully insulated cable as shown in the last image.
And again, if you prefer, you can wrap small amounts of electrical tape around the leads as an alternative to the heat shrink tubing. Just be careful not to use so much tape that it will prevent you from sliding the LED and cable up through the cork.
Step 6: Test the LED cable: apply power and Voila!
My recommendation is not to just plug this in your computer and see what happens. The best way to test this is to use a USB wall charger like the one that comes with an iPod or with other consumer electronics. That way, if something unlikely and bad happens, the damage is limited to a low cost gizmo and not your expensive laptop. If it works with a USB wall charger, then you should have no problems using it with your computer.
So, all caveats given, time to try it out. Plug the USB cable into the USB charger and you should see beautiful changing colors from the LED as shown in the image for this step.
Step 7: Assemble the base
1. Using a 1/4" drill bit, carefully drill a hole into the center of the cork. A simple trick to make it easy to keep the cork from moving while drilling is to push it into inside of the copper pipe fitting and then hold the fitting while you drill. When the hole is drilled, gently push the cork out from the narrow end of the fitting using your fingers or the handle of a small screwdriver.
2. Check for obstructions by taking the LED cable and gently pushing it through the hole. The cable should slide smoothly through the cork. It's better for it to be snug than for it to be wildly loose. If you find any obstructions remove them. Remove the cable from the cork.
3. Using a hot glue gun, put a ring of glue on the bottom of the nut and attach it the small end of the cork. Make sure that the hole in the nut aligns with the hole in cork.
The cork and nut are now attached as shown in the fourth image. The LED will stick up through the cork and within the center of the nut. The crystal will stand on the top of the nut.
Step 8: Final assembly - almost done!
1. Using a metal file, make a small notch into the bottom of the copper fitting. Remove just enough of the pipe for the USB cable to comfortably fit in the groove.
2. To make sure that you've made the groove large enough, put the cable into the fitting as shown in the second image and make sure that the fitting sits completely flat on a smooth surface. Remove the LED cable from the fitting.
3. Gently push the LED and cable through the hole in the cork until the LED is inside the nut but not poking out of the top as shown in the third image.
4. Take the cork/nut/LED cable assembly and insert it into the copper pipe fitting as shown in the fourth image.
5. Apply power to see what it looks like without the crystal. It should look like the last image for this step. Pretty cool, huh?