Third: Surface and Sensors

This is the most visible part of the build, so keep your work area and hands clean and try not get your fingerprints all over everything. It won't be like AWFUL if you're not all neat and tidy about it, and eventually you'll sweat all over it making futuristic music - but you'll be glad you did.

This is also the most forgiving aspect of the build, as you may have to do it several times to change colors of bargraphs or experiment with different touch surfaces, both overlays and underlays, and so I made this section easy to modify.

If you build it carefully you should be able to remove the touch sheet and sensors as a single unit, repeatedly, as-needed. The connectors for the sensors are simple 3-hole female connectors that fit onto the DRIVER board and slip on and off easily. Maybe a dab from a glue-gun at some point. They are sometimes easier to get on and off with the Arduinos removed.



Here's the LED board with the plexiglas sheet attached by thin strips of long-lasting transparent tape along each edge. [I use Staples "Long-Lasting" packing tape, which is thick, and cut it into thin strips with a ruler and x-acto. I get axactly the width I need, it's long lasting, I can cut it off and start over if I need to. Good stuff.]

The tape holds the sheet in place before the sensors go on, and also provides a tight band around the individual LED bargraphs, holding them together. It's a good idea to have the LEDs lined up as nicely as possible before you do this step. Once the sheet is in place, you have a nice solid surface to attach the sensors onto. The sensors will :"break-in over time. It's a good idea to burnish the clear plastic where the clear sticker adheres to the plexi while it's clean and new to remove any "fish-eye type issues. Over time the sensors become more reliable as they kind of "break in" and the connectors all settle.



Now connect the sensors to the Driver board, leaving the "3M" backing in place (trust me). One by one, unpeel the backing and carefully lay the sensor onto the plexiglas. Try to leave the top part of the sensor loose and line the sensor up to the second or third led - keep them all the same. Keep in mind the sensor is physically slightly longer than the 64 LEDs. The top 3 and bottom 3 LEDs do not light up. So center the active part of the strip in the column of LEDs.

Since the sensor is an off-the-shelf part designed for generic applications, the bus-bar runs though the left column of LEDs. And you'll see the maker's name in black letters. Neither of these are really that noticeable once it's assembled and in use, but they mark it as a prototype for sure.