Introduction: EL Wiro
This is a project that let's you sequence EL wires and holds them together in a nice laser cut display case of acrylic. It uses an EL Escudo Dos shield, a 3 Volt inverter, an Arduino, EL wires, acrylic, and a few other raw materials.
Step 1: Design Your Acrylic Cut-Out
I give my students a 20 cm x 20 cm piece of acrylic to work with. I would recommend keeping things fairly small. If you are beginning, big robotic projects lead to big problems.
The bottom 4 cm of the acrylic will be held against a piece of wood, so you will not have the entire piece of acrylic to hold your EL wires.
Here's a simple sketch in black and white. Students will need to make a better sketch with color. The shapes shown are going to be grooves that are laser cut into the acrylic. You cannot have any floating pieces that are not supported. For example, you could not make a "bullseye" with complete concentric circles because nothing would be holding up the middle parts.
Step 2: Acrylic Cutting
I cut out two squares of acrylic at 20 cm x 20 cm each. One serves as the laser cut part to hold the EL wires, while the other part remains uncut as a cover for the piece.
The act of laser cutting could probably be a separate tutorial on it's own. I used a 60W Spirit LS laser cutter to cut 3 mm clear acrylic. I drew my design on TechSoft 2D design software. Our EL wire is 2 mm diameter, so I put in channels that were 3 mm wide. I actually recommend drawing channels of 2.5 mm. Etch a line into your acrylic at 43 mm from the bottom to show where your wood piece will go (to support it all).
After the laser cutting, I stacked up the two acrylic pieces for drilling. Put four holes above the wood for sandwiching the layers together with bolts and nuts. Put two holes below the etched line for screwing into wood. I drilled into both acrylic pieces at the same time. Start with a small drill bit, and then move up to your full size to avoid cracking the acrylic.
Step 3: Making Your First EL Wire.
Use a ruler to measure your first channel. Take that measurement and add 12 cm to it. This extra bit allows you to make mistakes. Cut your first EL wire to that length.
Soldering the JST jumper cable onto the EL Wire is THE most difficult part of this project. Don’t underestimate how much you will mess this up.
Here's a great How-to-do-it by Adafruit on EL wire soldering.
Using wire strippers, take off 3 cm of the outer colored sheath. This should expose a clear inner plastic sheath. Now, use a smaller diameter part of your strippers to CAREFULLY take off 1.5 cm of the clear plastic sheath. This should expose the two angel-hair wires underneath. If you break one, that’s ok. Twist them together. Wrap and stick a tiny square of copper tape (5 mm x 5 mm) 5 mm below where the clear plastic sheath was removed. Wrap the angle hairs onto the copper tape.
Solder #1: Solder the angle hairs to the copper. Use minimal solder!
Solder #2: Solder one wire of the JST jumper to the copper. Black or red doesn’t matter. First use strippers to expose 1 cm of the wire and wrap this around the copper tape / angel hairs. Use minimal solder. Keep the solder well away from the exposed central wire.
Solder #3: The central wire is coated in a somewhat brittle phosphorescent layer. Use sandpaper (or maybe fingernails) to expose 5 mm of this. Do not sand the whole thing. Use strippers to expose 5 mm of the remaining JST jumper (black or red). Solder central wire to the jumper wire. Keep this well away from the soldered angel hairs.
Test your wire! I use a battery powered 3 Volt EL inverter with two outputs. I always test my new wire with a wire that already is plugged in and illuminated. If it causes the other wire to go out (and doesn’t light up itself), then you have have short circuited it. If the other wire stays glowing, but your new wire doesn’t light up, then you have one connection, or both, not working. In either case, snip off the faulty area and start over. By giving yourself 12 cm of extra EL wire to work with, you have room for mistakes built in.
Keep your exposed solder joints far apart from each other! If they touch, it short circuits. Cover the joint with electrical tape for heat shrink. Test your wire again.
Step 4: Make All Your EL Wires.
As you complete a wire, put a piece of masking tape on the jumper to signify where it goes in your design and label it appropriately. Do all your other wires and test each one as you go. Do NOT cut / create more than one wire at a time.
Step 5: EL Escudo Dos Testing
If you have reached this stage, it is because all of your EL wires work and are insulated. If not, go back to the previous step.
First, read Sparkfun’s tutorial on how to use EL Escudo dos.
Put EL Escudo Dos shield onto your Arduino. Use a 3V inverter to change the low voltage DC into high voltage AC. DC has positive and negative to it, thus the red / black cable goes into that port. For AC, there is no constant +/-. That is why the double black cable goes into the AC port.
Plug in your tested EL wires into the shield. Try this sample code to get started. Notice that EL wires are programmed exactly like LEDs.
With your computer powering the Arduino at 5 volts, it will likely work. However, you may need to swap the power source and get a 9-volt wall wart.
Save the sample code with a new name and manipulate it to make more awesomeness happen.
Step 6: The Black Foam Background
Use a utility knife to cut a 20 cm x 20 cm square of black foam board. This will serve as the background of EL Wiro. Put the laser cut acrylic piece over it. Use a thumbtack to make tiny holes that mark where each EL wire will poke through and where the bolts and wood screws will go. Now use a big nail to poke through the holes for the 4 bolts and 2 wood screws. Use a smaller nail to poke the holes for the EL wire. The EL wire holes should be in a spot that puts them closest to the wood base and Arduino. Push EL wires through the foam board and test them again to make sure they work.
Step 7: Making the Sandwich
Have you tested your wires again? In the last 5 minutes? Don’t even think of doing this step unless you are 100% certain they work. Unplug all wires (stuck in foam board) and set the black board down on a table. Put the laser cut acrylic over it and fit the wires into the channels (loosely). Now (very carefully and slowly) slide the top acrylic piece over the top while you adjust, push, finagle, your EL wires into their homes. When you’ve got this sandwich made, keep pressure on it! Use the 4 bolts and nuts to seal the deal.
Test your wires again. You better hope they still work. If any wire doesn’t work, you will need to trouble shoot it, and that probably means unmaking the sandwich. :(
Step 8: Securing to Wooden Base
Use the holes in the acrylic and foam board as a guide to drill into the wooden base. Insert 2 wood screws to hold it. I preferred to counter sink these wood screws in the acrylic. Attach the Arduino / EL Escudo to the wood base (nails or screws) and do the same with the inverter (hot glue or double sided tape).
You're done! Enjoy programming EL Wiro to make many awesome sequences.
Here's a video of my El Wiro (Triangulator) in action.
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