Illuminated CD Coaster

A coaster made out of an old CD or DVD that has a USB powered LED in the center; simple. The only interesting feature is that I included the ability to change out the LED if necessary (didn't solder the LED directly to the circuit), since I have a tendency to burn out LEDs and it facilitates changing the LED if desired.

Outline:
Cost: $3-15
- $0.99 for 5 resistors @ Radioshack
- $1.99 for 2 LEDS @ Radioshack
- Glues, tapes, etc.
- Old CD or DVD
- Solder and iron
- 5 Water bottle caps

Difficulty: Easy - moderate

Time: Less than an hour. More if the glue you're using has a considerable curing time or something.

Physical components:
- Old (or new) CD or DVD (I used a fudged DL DVD)
- 5 water bottle caps
- Cardboard, about 4-5mm thickness if possible. If it's thinner, you can always stack it.
- Tin/aluminum foil, about 3 square inches
- A ruler couldn't hurt
- Silver sharpie if you have one

Adhesives:
- Electrical tape
- Gorilla glue or hot glue (you need a glue with some substance)
- Super glue (gel or liquid, doesn't matter)
- Duct tape can't hurt
- Clear scotch tape or packing tape

Electrical components:
- A 3mm or 5mm LED - Color is your decision but I went with white since they tend to be MUCH brighter than any other color. I got a 7000MCD (MCD is a measure of light output) high-intensity white one from RadioShack for $0.99ea. In my opinion, I could only imagine using a 7000MCD or higher, because it's perfect-to-dim as it is.
- A resistor (68-500 ohms .. depends on your LED). For the white one that I used I needed a 68 ohm one. Use the formula R = (5V - V) / A .... where V = the typical (not maximum) voltage for your LED and A = the typical amperage (in amps, not mA, so 25mA is 0.025A) for your LED, both can be found on the package. R = the number of ohms your resistor should be rated for. LED calculator
- Some wire
- A USB type A male connector (best cut from an old USB cable)
- Soldering iron and solder
- A switch might be nice. SPST will work.

Optional components for removable LED:
- Thin copper wire or your alternative
- Flat rubber band or your alternative

First off, you've got a decision to make. This project essentially requires you to box this LED in where it's not easily accessible, not to mention soldering it. Should you want to replace it with a brighter one, change the color, or change it if you accidentally burn it out, you've got a lot of work ahead of you. Un-gluing, de-soldering, etc. I decided to spend some extra time developing a way to make mine easily changeable. You can save time, materials, and effort by it setting up straightforward, but I'm the type of person to always assume that the worst is going to happen (because it usually does).

NOTE: Since I made mine removable, the pictures in this guide show my little jimmy rig for removing it, so don't let that throw you if you're just directly soldering it.

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I didn't have any kind of connector that would be small or flat enough for this application, so I made one.

I happened to have a couple of inches of 10AWG stranded copper wire on hand, so I took 2-3 strands and twisted them together. I made a small loop around the LED lead and glued it down. Now all I have to do to replace the LED is pull it out and install a new one, and perhaps clamp the wires to the LED lead with a pair of needle-nose pliers.

This idea was heavily improvised and I'm sure that there are a plethora of more efficient ways to do it. Feel free to try anything and experiment with better ways.

- Cover the hole in the center of the CD with clear scotch tape. It needs to let light through but prevent water from coming through. You can put the tape on either side, but I decided to put it on the label side since I was using the data side for the top of the coaster.

NOTE: The duct tape in the picture is there because I had been using this DVD as a coaster for a few months already, and the tape helped it from sliding around so much. I decide just to glue over it, so that's not really a necessary step.

WARNING: Some CD's, mine included, have a thin film protecting the label side, and it has a tendency to come off. You can take your chances like I did and just glue stuff over it, but it would be wise to scape it off first, if possible. The feet shouldn't be under much stress.

- Glue your "feet" on the bottom of the coaster and let the glue dry.

- Cut out and glue pieces of cardboard on the feet for additional clearance and stability. I used about 4mm of cardboard (two 2mm pieces taped together for each). The diameter of the caps I was using was 3cm, so I made 3x3cm squares.

This is a potentially useless step, but the "reflector" helps prevent light from spilling out underneath the coaster, which may be desirable for some people, but I wanted to make sure that the maximum amount of light was going up toward the bottle. Turns out that the LED I used has a 30 degree viewing angle, so very little would spill out anyway.

- Take a piece of foil and shove it down into the cap. Be gentle and try to get it snug against as many surfaces as possible. Make sure to use the shiny side of the foil if it's different. I made the foil go over the edge and cut it about halfway down the cap.

- Before you glue it, cut the holes for your LED leads. I made X shaped cuts on the bottom of the cap on each side of the little nub with a razor, then punctured the foil. I tested it by putting the LED in properly and made sure it fit snugly, as in picture two.

- Now cut around the holes, I forgot to take a picture of this one, but if you look carefully in picture three, you can see the different color of silver in the center. I cut the foil away there and colored the plastic with a silver sharpie. Basically, you don't want the foil touching the leads of the LED or you'll short your circuit out.

- Glue the foil down. I used a liquid super glue, Krazy Glue. Don't use something bulky like gorilla glue, wood glue, elmer's kids' glue, gel super glue, etc. if at all possible.

OPTIONAL REMOVABLE LED: If you're going to install the removable LED bracket or whatever, this would be the time to do it. Good luck.

- Cut your USB cable, leave as much of the wire as you'll need. Strip off the outer insulation, about 3-4 cm worth. You should see 4 colors of wire: black, red, and two other colors. Trim the two colored ones, black and red is what we're interested in.

- Red is +5V and black is -5V or ground. CAREFULLY strip the small wires. About 1.5 cm

- Whether your LED is removable or not, solder the resistor to the anode, or the positive lead. The anode is always the longer lead. Resistors are non-polar, so it doesn't matter which side you solder.

- I soldered 6 cm of wire or so to the cathode, or the negative lead, so that it was even with the end of the resistor, to make soldering the USB cable easier.

- Solder the red wire to the other end of the resistor.

- Solder the black wire to the cathode lead (or the little extension cable).

- Ensure that no leads are touching each other, and that the foil is out of the way of everything, too. Then plug it in! Hopefully it lights up, if not; check your connections.

- If all is well, put electrical tape over metal parts.

- If your LED isn't removable, simply put glue on the rim of the reflector and glue it to the bottom of the coaster. You may want to trim the foil back so that you're actually gluing the plastic rim and not the foil, but I don't anticipated it being a major problem if you don't.

- If you DID make some sort of removable LED, figure out a way to mount it to the bottom so that you can take it off easily later. I decided to use rubber bands. I glued one side down, taped it for reinforcement, stretched it over the bottom of the reflector and glued / taped the other side down. One held it fine, but I decided to use two just in case, since the LED lead was digging into the first one a bit, and it was damaged.

- Once mounted, plug it in and test it out! Hopefully your LED/resistor combo is bright enough for a nice effect. Hope you enjoyed this Instructable and feel free to give me (inevitably negative) feedback!

- Couple your Illuminated Coaster with a USB charger for sweet coaster effects on the go! Mine is a MintyBoost.