Coffee table with touch sensors and LEDs
Once I'm happy with basic lighting and touch sensing, I'm planning to add USB port to it so it can act as a MIDI instrument for anything else. This way you can connect iPad and playback your coffee table presses through AirPlay to your audio system.
There are many apps available for it. All you need to do is to buy a USB dongle for your tablet.
I saw several ways of creating a matrix with cells for LEDs, but most of them involved too much special material, wood/acrylic working, and even laser cutting.
Once I was looking for some window blinds for something else, and then I realized that these are perfectly cut and sized for my project. They are cheap enough too. I'll have to make minor modifications to insert one to another one, but that's minor compared to other projects I saw.
I was experimenting with Infrared touch. First I tried to use a normal IR LED, but I got into issues with ambient light. I tried to substract it during calculations, but results were not stable enough for me.
Next thing I tried is to use 38KHz modulated IR LED. The results are much better. However, I need more powerful LEDs to be able to get through the glass surface and able to detect a reflection properly.
It appears that many high-power IR LEDs are not so high power. I tried IR LED from a remote control, that worked nice so I need to be able to get 400 of those without braking a bank.
I'm currently researching for the best (and cheap enough) touch sensors for the table.
My current candidates are:
1. Infrared sensors using 38KHz modulation
2. Custom capacitive sensors. I think I can do it with such low resolution (20x20), but it may involve running thin wire which I don't really like
3. Touch sensing film. It's expensive and I don't really like the idea of having something on the surface of the table