Wiring the LEDs for FTIR

I contemplated making my own PCB boards for the LEDs, but after doing some searching I found some boards online that would be more cost effective and work better than making my own boards. I decided to buy the following board from futurlec.com It’s possible to get 4 individual strips from each board for making individual LED PCBs. I needed a total of 10 strips for the two sides of my acrylic so I purchased 3 boards for $9.50. The strips are good because they will allow for 4-8 LEDs per strip. I chose to do 5 LEDs with a 1ohm resistor per strip (@ 7.5v), making a total of 25 LEDs per side of my acrylic.

The LEDs I’m using are the popular OSRAM SFH485 bought from digikey.com, but you can find them from many places.

PCB board Continue reading “Wiring the LEDs for FTIR”

Building the Table Frame

I went to home depot and picked out some wood that would be good enough for the inside framing of the table. I tried to get something light weight and sturdy. The main reasons for the frame is to keep the table sturdy and also make it so the walls of the table will be square, flush, and have something to screw into. I measured out all the pieces in google sketchup and then had someone at home depot cut the pieces to size.

Continue reading “Building the Table Frame”

Building the Top Frame

From the Google sketchup file I created, I measured and fabricated the top frame that will hold the LEDs, acrylic, silicone (compliant surface), and projection layer. The top frame consists of two pieces; the top piece, which will fit the acrylic (in the center), along with the silicone rubber and projection material on top, and also the infrared LEDs alongside the acrylic and the bottom piece that will screw into the top piece and rest on top of the final box.

Top piece (left) and bottom piece (right)

View of the top and bottom pieces (with acrylic and LEDs sandwiched in between).

I bought two pieces of 4 foot x 8 foot x 1/2 inch thick hardboard at home depot for $15. I had them cut it to the right height and width to make things simple. I then cut out the center of each board to the size needed. For the top piece I routed out around the edge of the center where the acrylic would lay. Then I routed the horizontal sides farther out so the LEDs could fit inside the frame. I routed out a little more than 1/4inch of depth so that the acrylic would fit nicely and also so that the LEDs would have room to fit also.

Here’s the top piece laying upside down. It matches the sketchup pretty well.

Here you can see how the acrylic (and silicone) fit into the inner routed part and how the LEDs will eventually lay.

For the bottom piece, I cut the center out a little wider than the top piece. I did this to ensure the camera will be able to see the whole surface and also ensure the the top surface wasn’t obstructed by the bottom piece.

Here is the bottom piece. It looks pretty much like the top piece without the routed parts.

Once the LEDs are all soldered together and ready to be mounted in place. Both the top and bottom pieces will screw into each other creating a single top frame (like the second image below). There is about 1/4 inch from the top piece to the acrylic which seems to be a nice distance from frame to surface.

Here’s the top piece (top view) with the acrylic with tracing paper on top and the bottom piece underneath.

Musical Squares update!

Well, I’ve made some additions, some changes and came up with an overall complete version of Musical Squares. Complete does not mean finished though, expect massive updates and much more functionality. This version is good enough to be called “Version 1” I would say.

In this version, I changed the 8 original notes to 5 notes (pentatonic scale) with 3 percussive tones. It sounds…well..interesting. I also added the ability to remove squares by dragging them outside the main stage and adding new squares by pressing on the colored squares on either side. Continue reading “Musical Squares update!”

Musical Squares…get it?

Well, Musical Squares isn’t anything like Musical Chairs, but it’s fun nonetheless. Who wouldn’t like throwing around objects that emit tones (sounds) when they hit each other?

I started working on this second music program as an aim to explore other musical possibilities. Right now there’s not too much functionality, and it’s a basic proof-of-concept as there isn’t much practical application for it yet. It’s based off another existing (single touch) online program called “Pianolina” that I hope to improve and build off of. The most recognized aspect between the original application and this one will be the multi-user, multi-touch aspect.

There is still a lot to be done to make things not so chaotic sounding. Currently, you can throw the blocks around and also resize them using two fingers on the block. The nice thing about resizing is that you can create more likelihood that a bigger block will “sound” thus giving more emphasis to certain pitches (just like in most music). Continue reading “Musical Squares…get it?”

MultiKey – My first application

MultiKey is a simple multi-user, multi-touch music application. In the standard version, there are two music keyboards. One is a full octave, while the other is two full octaves. By pressing on the white border, the individual keyboard will switch into move/rotate/scale mode and can be rotated and resized to your liking. Press on the white border again, and move/rotate/scale will be turned off. Have fun!

MultiKey v1.3

Possible Future Changes/Additions/Bug Fixes:

-Ability to change to different sound library
-Ability to add (drag out) multiple keyboards. Idea: use a gesture that is assigned to keyboard creation.
-Add some kind of dynamic movement in background when key is pressed since keys are transparent.
-Fix canvas and create ZUI so pianos don’t fly off of screen range.

How it Works:

1) Start FLOSC,
2) Open Touchlib OSC.exe,
3) Start up the application (exe or swf).

If you would like a different set of keyboard sounds. Replace the mp3 files with your own. Rename them to the same as in the folder. A = A natual, As = A sharp etc.


If you have comments, would like certain features added or would like to add them yourself, please comment below. I will also add them to the “Possible Future Changes/Additions” section. Thanks and have fun playing!

Download Links Here: Source Code MultiKey v1.3

Download Links Here: Binary MultiKey v1.3*

*Note: I’m including both the exe and swf. If you use the swf, make sure to set the security settings so you’re able to connect to FLOSC.

The Cured Silicone

After waiting about 20 hours and letting the silicone rubber cure overnight, I went ahead and “unmasked” the silicone to see how it cured. From the look of it, it cured quite nicely. It isn’t completely even as far as the whole thing being completely smooth and 1mm thick, but this really shouldn’t affect it’s performance. After further inspection, I found that there were no bubbles in the silicone! Bubbles are one of the main concerns when pouring silicone yourself. I think my success had to do with mixing the A and B parts for a good amount of time (12 minutes).

Continue reading “The Cured Silicone”

Pouring the Silicone

Well, the silicone arrived today. It took 5 days from the time of ordering online. I’ve done a lot of research, talking to others that have poured silicone and watched a couple videos so I was prepared for what I needed to do.

The best video to date is from Blaxwan and it really provides great documentation and information on how to pour the silicone.


Here are a couple things not mentioned in the video that I would like to add:

1) Make sure that you read the directions carefully on the package.

2) Measure out the portions of A and B by weight (not volume) with a gram scale. The main reason most people don’t get the silicone rubber layer right the first time is due to the A/B ratio being incorrect.

3) Be patient, but work fast. Although this particular silicone doesn’t fully set for an hour, it does start to set in about 30 minutes from the start of mixing the A and B portions together. After 30 minutes, it becomes harder to smooth/level out the silicone so make sure to use your time wisely and plan things out beforehand.

4) Once dried, DO NOT TAKE THE SILICONE OFF THE ACRYLIC. The idea is for the silicone to have no bubbles and stick to the acrylic. By taking the silicone off when it dries, air bubbles will be introduced in between the silicone and acrylic which is not ideal.

My Setup:

The sorta Clear 40 arrived in this little package with two different parts. Part A is the tub with the silicone which is sticky and thick, and Part B is the activator which is a liquid.

Before starting, I prepared the table (like the video) by putting an old table cloth over it, and laid newspaper down and put the acrylic on top. It’s hard to see the acrylic since it’s very transparent. Since I didn’t have U-channels to put on the sides of the acrylic for leveling the silicone, I put layers of blue tape on each side. I continued stacking tape until it measured 1mm above the acrylic which came to 8 layers of tape on each side.

I used a straight metal beam (purchased at Home Depot for $2) for leveling the silicone. The beam fits over both sides of the acrylic where the tape is and glides smoothly over the acrylic about 1mm above it.

Here you can see a closer picture of the tape and setup. Once the leveling of the silicone is completed, I placed blue cups around the acrylic in order to hold up cardboard and a cloth while the silicone cures (dries).

Once the silicone is leveled out and the cups are in place on each side, I placed a cardboard box on top of the cups. This gives room for the silicone to cure as a sheet will be placed on top of the box.

Finally, another old table cloth was positioned on top of the cardboard. This is necessary so that the silicone doesn’t acquire dirt as it sets.

Compliant Surface Samples

Well, I recieved a couple samples of possible compliant surface silicone sheets. Unfrotunatley after some testing, I’ve found they won’t work for FTIR use.The first is from www.rubbercal.com. The durometer (hardness) of the sample is just too high (probably around 70) and therefore doesn’t stick to the acrylic at all. The other sample I recieved is from Rubber House on ebay. This sample is just too thick (1/16″), although it may be a great alternative if the supplier ever gets 1/32″ or thinner sheets in stock.

Since these samples did not “do the trick” and other mentioned brands posted on nuigroup.com aren’t ideal, I’ve decided to go ahead and order Smooth-On Sorta Clear 40 since it has been recommended on NUIgroup. This means I will be pouring my own silicone rubber sheet If everything goes as planned, this will also be the cheapest way of getting a compliant surface. It costs about $33 + $12 (for shipping) at the Smooth-On webstie for a trial size (2.2lb) which should be big enough to make a 36″ x 48″ size silicone sheet (1mm thick). That’s about double the size I need.