Nuts and Volts - September 2014

substance with more magic is duct tape. Its magical properties go far beyond what mere mortal words can describe. There is nothing you can’t accomplish with duct tape. It is the holy relic of the crafting world.

Building the Eye Segments

Place the MDF panel with the eyes and mouth cut on top of the light box. It’s time to create the segments in the eye. Don’t tape the cardboard down until you check its position and add the LED strips. Use three cardboard tubes — like the kind found in paper towels — to mimic movement of the pupil. This is going to allow the eye to look left, right, or straight ahead. Use a cardboard tube that’s larger in diameter in the middle. This is going to make the face look surprised. Finally, add a cardboard division above to frame the pupils which will make the eyes look angry.

An optional part to make the animated display brighter is to use a sheet of reflective Mylar and tape it down to all of the surfaces you want to illuminate. Mylar is the stuff that metallic balloons that are caught in power lines are made of. It’s also sold as “space blankets.” You can try to find Mylar locally at an Army surplus store or strangely enough at a hydroponic store. (Why people would ever want to send a plant into space wrapped in Mylar is a topic for another article.) Aluminum foil could be used as a substitute, but it’s not as reflective. Another alternative is reflective spray paint.

The LED strips that you want to use for your animated display are the 12 volt non-weatherproof cuttable strips (Figure 6). There are waterproof LED strips that are cuttable, and at first you’d think that these are the type of strips you’d want to use since this display will be outdoors.

However, the weatherproof version of the strips cannot be soldered again once cut as they have a rubber coating on top of the solder points. The non-weatherproof strips have these solder points exposed, so you can get more segments out of the strip. Cut the strips long enough to line the segments, solder wires long enough to reach the LED controller, then tape down the segments.

Building the Mouth Segments

The mouth segments are a bit more complex than the eye segments, but it’s not difficult once you understand the assembly. From your leftover MDF,

cut out two shapes that match the two innermost pieces of the mouth (Figure 7). Now, line the MDF shapes with cardboard as shown. Tape the cardboard to the MDF cutouts or use a hot glue gun if you don’t mind the occasional burned finger. There should be three segments made from the two pieces of MDF. The smaller shape will be the tongue. This shape will sit on top of the larger one.

The larger shape has two segments. The upper segment is for the lips that are used to make the M/B/P sounds. The lower segment is for the lips in a smile position. Leave the lower piece of cardboard long for the larger shape as it will be used to create the upper part of the middle mouth. Add one more piece of cardboard for the bottom part of the middle mouth. Add Mylar (if using) and the LED strips like you did with the eyes (Figure 8).

Finishing the Face Front

To finish the face front, cover the front of the MDF panel with Mylar (again, if using) and cut out holes for the eyes and mouth. I’m using spray adhesive to attach the Mylar to the MDF. Use some more LED strips to line the MDF panel so the entire face will be illuminated. Next, create some standoffs between the MDF panel and the diffuser. The diffuser works better when there’s some distance between it and the lights it’s diffusing. I found that a distance of four inches works well to remove any ‘hot spots’ created by the LED strip.