Repurpose LEDs for Shadow Box Lighting

I love making and fixing stuff and wanted to share this idea of mine with everyone at the Instructables site. Please see my website ShareYourRepair.com for hundreds of other ideas, repairs, and hacks. I originally wrote up this tutorial there and have written in even greater detail on my personal website.

We had an Antworks Ant farm which the ants had long ago died. It included a LED light base. When we threw out the old moldy ant farm I kept the base, thinking I could some day re-purpose it.

Recently I made a shadow box for a dragonfly we found. Soon after that I was cleaning out my workshop and ran across the LED circuit and the idea clicked to install the LEDs in the shadowbox and it turned out really neat. This idea has a lot of application for other LED circuits so just because you don't have an Antworks ant farm, you still may have a LED circuit laying around in which you can apply this same technique and create something really cool!

Tools/Parts I used on this project:

• Fascinations AntWorks Illuminated Blue
• Shadow Box
• Safety Glasses (never solder or use a Dremel without them)
• Phillips Screwdriver
• Dremel Tool
• Dremel Drill Bit Set
• Dremel Router Bit
• Dremel Keyless Chuck (for inserting the tiny drill bits)
• Soldering Iron (this is the model I purchased and I really like it)
• Solder Sucker (for removing bridged solder joints and/or to help in unsoldering the LEDs)
• Extra set of hands (a very handy tool for soldering electronics)
• Wire Stripper
• Flush Cut Wire Nippers
• Hot Glue Gun
• 6-Inch Spring Clamps (handy to hold stuff together and to hold your extra set of hands in place)
• Solder
• Glue Sticks
• Fine Insulated wire (I used old Cat-5 Cable but you could use old phone cable, or even better yet, magnet wire, but make sure to scratch off the enamel from the ends of the magnet wire before trying to solder it, otherwise it won't stick)

I think you will have better results if you have a goal or a vision and mine started out with re-purposing the LEDs in my shadow box.

I forgot to take a picture of them before I removed the LEDs but they were inside the plastic base I have pictured and I wanted them out. I carefully pried the top up and out with a flat-head screwdriver. After I got the top off there were two phillips-head screws I removed to completely free the LEDs and the circuit board they were mounted on.

You will need to keep track of the polarity of your LEDs. Typically LEDs have a flat side on the Cathode (-) side and the Anode (+) side has a longer wire leg, to help you identify the proper wiring. Since these LEDs have already been soldered in place and the legs cut off and I couldn't see clearly a flat side so I simply put a piece of masking tape on each one and marked the positive and negative sides with a marker, before I unsoldered them, for easy identification later. This circuit board was nicely marked with the polarity so I could tell for sure. I also could have plugged in the circuit and checked the voltage with my multimeter to determine the polarity if the board had not been marked. If the voltage on the multimeter shows up as positive you know the red lead of your multimeter is on the positive terminal (mark it with a magic marker)--if the voltage shows up negative then you know that your leads are reversed and you have the red lead of your multimeter on the negative lead of the LED.

To remove the LEDs I was able to hold the LED with one hand and then heat both solder joints on the back side of the circuit board at the same time and pull the LED out. Try not to heat the LED up too much or you could damage it.

I used some old Cat-5 cable that I saved for times like this. I was consistent in the way I hooked up the wiring and I used the dark wire (blue in this case) as the negative (-) and the white wire as the positive (+).

I left the wire extra long, probably 6-inches, because I didn't know exactly how long I would need it but I did not want it too short. You may need to heat up the solder on the circuit board in order to push the new wires through. This was the perfect time for me to use my extra set of hands tool, which is so helpful in times like this. I clamp the base of my extra set of hands in place with a 6-inch spring clamp so they stay put.

After pushing the wires through the circuit board I added solder and soldered the wires in place. Then cut off the excess wire with a flush cutter (get one if you don't have one--they are so handy). Make sure you don't bridge the positive and negative solder joints together like I had happen in the third picture. I simply heated up the solder and used my solder sucker to remove it, and then re-soldered them. Look at the next picture to see what a good set of solder joints looks like (I had already trimmed them off with my flush cutters). In the second to last picture you can see all four sets of wires soldered in place. Finally I show you a picture of where I plan on mounting the circuit board.

I wanted the LEDs to be evenly spaced. This shadow box has a spacer frame that presses the glass to the front of the frame and holds the picture against the back of the frame. The spacer was approximately 7 inches square. That gives me a spacing of about 1.4 inches. I measured the center and then went left and right from there (.7 inches to the left and right of center, that is). My LEDs' legs were 0.1" apart so I spaced the holes at a tenth of an inch and used a generous size drill bit to give me some room but not enough so that the holes could be seen out from under the plastic head of the LED (I wanted them hidden). I ended up needing to transfer my marks to the outside of the frame because I couldn't fit the Dremel in the inside of the frame to drill the holes straight through.

Tinning is melting solder so that it coats the ends of wire. Once solder has "adhered" to a wire it is much easier to solder that wire to another wire. Since we don't want to overheat our LEDs we want the solder joints to set as fast as possible and tinning the wires will help us a lot. The LED legs have already been tinned since they were soldered into the circuit board. Be careful not to leave a big glob of solder on them though, or they won't fit through the hole.

Make sure you keep track of the polarity of the LEDs and connect the positive wire from the circuit board to the positive leg of the LED. In my case the blue wire is the negative and the white is the positive. Don't use too much solder--it doesn't take much. The fresher the solder the better (ie you just melted it off the spool and there is flux mixed in with it) versus solder that's been cooking on your soldering iron tip and all the flux/rosin has been burnt off.

Double check your wiring first and then power it up to make sure everything is good.

I need to create channels for each set of wires so they can run out without causing the frame to bend. I chose this type of Dremel router bit I have pictured. Be careful not to hit the wires with the Dremel. You may want to do this step BEFORE you solder the wires to the LEDs. I also would suggest making a deeper channel than I did to leave room for the glue you will add later. Hindsight is 20-20, learn from my experience.

With the spacer frame in place I marked where I needed to notch the back out and then cut some notches so the wires could get out. I then installed the spacer frame and ran the wires out the back.

I installed the spacer frame in the outer frame but the LEDs pointed in every which direction since nothing was holding them in place. Because I located the LEDs close to the picture, they appear like little spotlights on the picture and so it really matters that they are all straight. If you place yours farther away from the picture it may not matter as much. Push the LEDs tight down in their place, while simultaneously (gently) pulling the wires through the holes, when you are gluing the wiring so it will hold the LED in place. Then liberally hot glue the wires in the channel you made and this should hold them still. You can bend them to point them straight after the glue has dried.

When I put the spacer frame inside the outer frame, with the newly glued LEDs in place, the extra thickness the glue creates caused the spacer frame to bow up in the middle (which in turn fanned out the light beams the LEDs made). I wish I would have taken a picture but believe me, unless you have superhuman hot gluing ability it's hard to put a tiny bit down without adding thickness to the frame. I wanted it to look good and for the wiring to not effect the look, so I used my Dremel router bit to make some space for the wiring and glue. You could possibly avoid this step by making deeper channels for the wires to run in step 9.

It is looking really neat and adds to the Dragonfly project. You can bend your LEDs to straighten them out and make sure the paper artwork is laying flat or it will be obvious too when the lights shine on it. I was really happy how it turned out.

Take note of how the cord will connect to the circuit board (so it hangs down in a good place and doesn't naturally get pulled out of the socket). Now that everything is working I glued the circuit board on the back of the frame. Leave enough slack in the wires so you can take it apart again (to clean the glass for example).

Find a spot where you can plug it in and not have the wires showing. It's so fun to feed your kid's imagination and have fun doing it! My daughter loves it. It even looks neat when in a bright room.