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In this tutorial I explain how to build an EL-wire decoration to put under a T-shirt and how to drive it with electronics to make it move in beat with ambiant music.

This is the ultimate wearable decoration to wear in electronic music festivals or clubs.

The idea is to hide felt panels under a t-shirt and drive the lights using a microcontroller that analyzes ambiant music with a microphone.

For this project, you will need :

-two simple white T-shirts

-EL-wire

Depending on the length of EL-wire we need, we have to choose between two power inverters. If I had used less than 3 meters of wire, I would have chosen a 3V inverter. As I planned to use more, I chose a 12V inverter.

-so a 12V inverter

-12V batteries, I chose 8 NiMH AA type batteries of 1.2V each. It’s not exactly 12V but it’s sufficient.

-some electronics (EL Sequencer with an integrated microcontroller to analyse the microphone and drive the lights

-a microphone (mine is cool, it has automatic gain)

-a small switch

-felt sheets approximately the color of the T-shirt to be able to sew logos on it (the T-shirt would not be resistant enough.

I needed also small supplies, solder iron, tools, wood,…

Step 1: Draw Your Shapes and Solder the EL-wire

First you need to have an idea of the shapes you want to have with your EL-wire. Then you approximately select the length of wire you need and cut it (with some more length just in case)

EL-wire comes without electrical connexions and can be cut where you want. But each time you cut it, you have to connect it to the power source. That’s one of the hardest part of the project, you have to denude very small wire, solder them without breaking them, put shrink tubing around them to secure them,… I won’t get into details, someone explains it better than me. Actually I have red different tutorials here on Instructables to make my own procedure to solder EL-Wire.

Now you should have EL-wire strips with electrical connexions. You can check them by connecting the cables to the inverter and see if it glows.

Step 2: Sew the EL-wire on the Felt

I drew my pattern on the felt and then sewed it to give the shape to the wire. I made holes to pass the wire at the beginning and at the end. As the EL-wire is very hard to solder, I tried to minimize th number of times I cut it. I also simplified the patters I wanted to draw.

Another idea is to hide the wire behind the felt in the places you want to hide it. As an example, on my smiley, I used one segment to make both eyes. If there’s a corner or a sharp edge to draw, make a hole in the felt, and do the turn behind the felt before going out of the hole in another direction.

Step 3: Connect the Electronics

When the wire is connected, you can plug it on an output port of the EL-Sequencer. There are nice male plugs on the board but I haven’t any corresponding female lying around so I made myself connectors on the board. You can also solder the wires directly on the board.

The battery connector goes on DC IN, the inverter goes on DC OUT and AC IN. I put a plug on DC IN to be able to turn everything off easily. If everything is well done we can power it on and with the default program loaded on the microcontroller the wire should blink.

You can connect the microphone OUT to the pin A2 of the microcontroller, also Vdd to 5V and the ground of the microphone on a ground pin.

Step 4: Program It

Get the bass from the microphone

In many engineering domains, analyzing frequencies is very important. It’s often achieved by applying the Fourier Transform Theory. It’s very powerful but the mathematical description of it need integrals, complex calculus and only works for perfect signals. I’m in the real world, and my microcontroller doesn’t know how to evaluate complex integrals. Hopefully, there’s an applied version of this theory called Fast Fourier Transform (FFT) that is a very well known method to do an analysis like that with a computer. Still, it requires some calculating power that my microcontroller doesn’t have. I found another algorythm called the Fast Hartley Transform (FHT) that is simple to use and works well too.

I copied the example code of the library I found and began playing with it to make the lights blink according to the levels of certain frequencies and I was done. I tested it at home, it worked well. Oh, wait, what if in a loud music environment it doens’t work ? Let’s find a plan B.

Surviving in the real world

So as I will use this in an environment with loud music, crowd, drunk people pushing everywhere,… i need to make my T-shirt (and the electronics inside) solid enough.
As I was not entirely sure the microphone would work in very loud music environment I programmed a plan B on the microcontroller using a switch. With that switch I can run the T-shirt in a sequence mode with random patterns. Otherwise it runs in sound mode. It turned out that even if sometimes the microphone was saturated, overall it worked well all the evening. The electronics is put into a small wood box to protect it from impacts. All the wire soldered on the board are hot glued around the solder point to reduce damages on them. Everything is placed in a small bag at the belt in front of me under the T-shirt.

You can use the attached source code on your setup and play with it.

Step 5: Test It and Have Fun

Here is a demonstration of the audio feature :

<p>Nice use of the FHT library. Was thinking that beat detection was going to be a real bugbear, so I'll try your simple 'check the level' method with one of my FHT bins and see how it goes with my LED's.</p>
<p>cool !!!! You can add a control system, and your costume will win any party! https://www.youtube.com/watch?v=Q8c6u_P4lUM</p>
<p>A very cool idea and it obviously works very well, but my <br>generation (I&rsquo;m 67) could appreciate something a bit more conservative since only <br>some of us can even remember some of those loud parties. How about your idea <br>with only a red (or blue) heart showing on the T-shirt with an adjustable <br>current that would appear to beat like a heart? The heart could appear as a simple <br>heart shape or as a real heart with the arteries fading back into the body. I <br>know this would look a lot better on a woman, but&hellip; Women would love seeing that this man actually 'had a heart' and when asked what it was he could say he was <br>wearing one of those &lsquo;copper threaded&rsquo; shirts (like they advertise on TV) and <br>this is what happens to his heart when he sees a beautiful, intelligent woman. Although she (probably) wouldn't believe all of that it would certainly start an interesting conversation, even for a younger crowd.</p><p>I currently don't know enough about this process to make an 'excited heart', but with instructions like above, I would have to make one.</p><p>Thanks for your great idea, FallsLakeBob@gmail</p>
<p>That's a wise idea, I like it :)<br>If you already have a t-shirt , say, with a heart drawing, you can draw the outer shape with el-wire to get it more interesting.<br><br>I'll just add, technically speaking that fading the intensity of the EL-wire with a microcontroller is not trivial. EL-wire is powered with an AC signal and fading it with microcontroller's PWM can mess up with the AC frequency. <br><br>What I have in mind is the wire beating as a heart, flashing like you would hear it :)</p>
<p>Thanks BobChidie, </p><p> That is a better idea and beating like a real heart would certainly get more attention. I still think it would be better to make it for a woman and carefully walk the thin line between getting attention and getting too much attention. On a woman you could even make it a 'broken heart' or to make it even more intriguing (or even challenging) a heart with a circle around it and a diagonal bar through it like the new 'do not enter' road signs.</p><p>I think I need to find an 'age appropriate' woman that still has a good sense of humor and adventure, and that will certainly take another and more complicated instructable. </p><p>Thanks, Bob </p>
<p>Sir (bobjacksonjr), you know how to get some.</p><p>Very wise!</p>
<p>Hello Dude! i would like to know the inverter voltage for different lengths. Source for the EL wire and any spec.</p><p>regards</p>
<p>I think you should read the specs of the suppliers like Sparkfun or Radioshack to name only them. They sell inverters and tell what lengths you can power with it.<br>Here are some precise specs : https://learn.adafruit.com/el-wire/using-el-wire</p>
<p>This is way cool. Would like to see this implemented with something other than 8 heavy NiMH batteries though, maybe some CR2032 flat lithium batteries. Not sure how long they would last since the typical capacity is something like 190-225mah.. but you could stack 4 of these and be MUCH lighter and less bulky, but it would involve all new hardware since its 2.8-3v. You probably could make a pretty simple PCB with minimal components as well for beat detection, not near as fancy as FFT or the like, more like gain detection, but could serve the same purpose. I really like the idea though, have thought of it before, but its great to see someone actually go through with it and make a working model. +1</p>
<p>Yeah, of course, and I even think that these little flashing circuits with a microphone are already on the market.<br>I wanted to try if we could use something more reliable and less influenced by noise.</p>
<p>Bobjacksonjr- as a beautiful intelligent woman I say &quot;yes a heart is a good, no GREAT thing&quot; and to BobChidie (the creator) AWESOME! Also in your picture in the instructable it looks like the guy in front of you in the green is having a little too much fun:-) </p>
<p>Dude! Seriously! This is a million dollar idea! Think about it!!!</p>
<p>I take it you haven't seen: eltshirtco.com. </p>
So the question we all wanna know.. Did it get u laid?
<p>Oh man, I can't say here what happened next :p</p>
<p>Very cool! </p>

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