Soft Circuit Hanging Wall Music Visualiser
The original project idea was to make a large-scale music visualizer that would be displayed on a wall. I was only sure about a couple things: I wanted it to be large ( at least 30” wide), and I also want it to take music as input live through a microphone and not through an audio jack connection to a pc or mp3 player.
My Original Idea
One of the things that gave me the idea for a wall music visualizer was when a friend showed me a website that sells an eclectic mix of “scientific” parts. I came across some 2x3 inch LED diffuser plates, and their dimensions reminded me of the rectangles seen in the columns in many music visualizers / VU meters. So originally I planned to use the LED diffuser plates (made out of some sort of plastic) to create the rectangle “blocks” of the visualizer.
My Final Idea
The led diffuser plates would have been to costly and also a hassle to set up. -> Would I create the visualizer on a wooden panel? That would get really heavy and be difficult to hang on the wall. Would I create the installation directly on the wall? That would potentially damage the wall, and also end up too difficult to transport.
I finally realized that I could use fabric and soft circuits to make a really practical visualizer. It would be simple to hang up because you could just pushpin it to the wall. It would be easily transportable because it is so light and flexible and could be rolled up. It would also be much more cost-efficient than the led diffuser plates (I don’t remember the cost of each 2x3 inch plate, but I found them online somewhere and they were really quite costly).
The Microphone Input
The input of the example music visualizer code I was using took its input from the earphone socket using a cable. I wanted my input to be live from any ambient noise or music in a room.
I had a couple of spare electret mics but I knew from a past project that I couldn’t just connect it straight to the arduino and have it work correctly. I needed to create a circuit that would amplify the input and have it feed correctly to the arduino. I honestly don’t understand everything that goes on in all of my circuits.. often times it is guess and check and I can’t quite explain much about the mic circuit.
I researched many different ways to make circuits that amplify the input of a microphone and finally settled on one (with one or two minor modifications). Sadly I don’t have the link anymore.. a month or two ago my computer got a virus that wiped the entire hard-drive, which included all of the bookmarks and research I did on this project over the summer. I still have some links in this wiki because I remembered enough of the information to re-find them through google. I think I remember searching for something similar to “electret mic amplify circuit.”
I soldered long wires to my mic for two reasons: 1) it was easier to work with while prototyping on the breadboard and 2) so that I could adjust its placement more easily later when I attached it to the final visualizer panel. Once I got the circuit working on the breadboard I soldered it to a mini pcb board. I chose to solder it rather than user soft circuits because I didn’t want to ruin the input signal. The conductive thread I own has a pretty high resistance, so much so that in the past I would have resistors on the breadboard prototype, but when I turned it into a soft circuit I had to remove the resistors so that my circuit would function. I also knew that I wanted the circuit to be small because I wasn’t exactly sure of the placement of it yet, and it was much simpler for me to do that with a normal circuit than with fabric and thread. It wouldn’t affect the overall flexibility (or the ability to be rolled up) of my design because it was so small and would be placed near the top or bottom.
The signal that this circuit was picking up and sending to my program ended up being a little too weak, and a friend of mine helped me figure out that I could add a capacitor before sending it to input to solve the problem. It’s not yet in the photo above, I had to solder it on later..
Diffusing the LEDs
I needed to find a soft circuit way of diffusing leds enough to create a rectangle of light. I first tried googling for hours and hours on soft circuit ways to diffuse leds. I really didn’t find anything useful..
What seemed like a logical step was to recreate the idea of the plastic led diffusing plates with fabrics. I got a bunch of different fabrics to attempt to create similar plates: a matte clear plastic “picnic table cover” fabric, a shiny clear “picnic table cover” fabric and several different silver, reflective fabrics. To test them I cut them into rectangles and layered a few of the clear plastics over one silver fabric, punched a hole in the middle and placed a lit led in it. The result was very disappointing. The LED’s light was not dispersed at all through the plastic fabric, no matter how I layered them and the silver fabrics.
Next I google searched for any way to diffuse LEDs, not just soft circuit methods. I found an Instructable about using hot glue on top of an LED to diffuse the light. This was much better than my original attempt with plastic fabric, but was still nowhere close to how bright or large of an area as I wanted.
After that I found an Instructable about diffusing an LED’s beam by sanding it down, which is supposed to give it a larger viewing angle. This ended up working really well, but still didn’t diffuse it enough to hide that it was a pinpoint of concentrated light.
I finally ended up coming across this LED quilt display created by Katie Dektar. She used normal quilt batting and it seemed perfect for spreading the glow of the leds. Together with my sanding, I felt like it would give me enough diffusion to light up a rectangle on my visualizer.
Creating the Display
The batting diffused the LED into a circular glowing spot, and I wanted geometric rectangles. To achieve this affect I decided to cover the entire music visualizer panel with a blue, non-transparent pleather, and cut out the rectangles where I wanted the LED light to show through. With testing it turned out that the maximum rectangle that I could properly light up with the amount of LED diffusion I was able to get was one 1”x2” rectangle. The size of each rectangle was the main factor in deciding how large the entire music visualizer would be (25” x 35”).
The grid contained 30 LEDS so I measured and cut out 30 1”x2” rectangles.
Under the pleather layer I had a plain layer of white cotton fabric. I sewed around each rectangle and cut off the excess white fabric that was in between the rectangles. With some more testing I decided that two layers of cotton batting between the LEDs and the pleather gave me a good balance between diffusing the LED into a less concentrated point and dimming the LED too much. 3 layers of batting looked nicer and diffused the LEDs to one even light but would have been less visible from a distance, which is not good for a large visualizer hanging on the wall.
The Soft Circuit
I cut another piece of plain white cotton the same size as the visualizer to use as my soft “pcb board.” I traced the pleather’s rectangles onto my pcb fabric to make sure my LEDs would line up with their respective rectangles correctly (this was before I sewed the white fabric to the rectangles). Then I started drawing on my LED grid circuit with the help of the LED Matrix Panel Instructable and the progress images on Katie Dektar’s LED Quilt Display page.
Both of those had different ways of dealing with the rows and the columns intersecting. I have yet to find a practical way to do this.. for the time being I just put tape over the rows at the intersections before I sewed past them with the columns.
I left out the resistors because I had the feeling the resistance of the conductive thread would be too high to use them. I know this is a very unscientific way to decide things, I guess the better option would be to use something to measure the respective currents going through my breadboard circuit and my conductive thread…
In order to connect the LEDs and transistors to my soft circuit, I bent and manipulated the wired ends to have loops that I could sew through. (I learned this making jewelry a long time ago. :p) I included an image below (found on Beadingdaily.com) to give a better idea of what I did.. I did this twice on each component, once on each wire.
Troubleshooting: I realized that sometimes the frayed ends (or just extra length I left) of the knots in my conductive thread that would accidentally touch other parts of my circuit. I was paranoid of short circuiting something (I’ve already ruined a pin on my Arduino somehow..), so I taped all of the ending/beginning knots of my conductive thread down to prevent them from moving around.
After testing the finished LED grid circuit and making sure it worked, I attached the microphone circuit.
Once I finished sewing the circuit and tested it to make sure it worked, I was ready to assemble the whole visualizer. I connected all the layers so that the seams would be on the inside. I also attached a zipper so that if I needed to fix or change something I could open it up and turn it inside out to do so.
As of now the microphone is still not attached to the panel: it is impermanently connected to the arduino. There are many things I plan on changing about this design and I want to make a whole new music visualizer with a ton upgrades as my next project. :]