Nuts and Volts - June 2015

one LED to one rod relationship around the perimeter.

With this arrangement, I would have light from the display patterns moving in both the X and Y directions across the LED matrix, and I would have light moving up and down in the Z direction as well, because of the varying lengths of acrylic rods. In addition, I would have three different sizes of rod ends, like little glowing discs that would be lit from the LEDs below.

When I finally visualized how this thing might look and how it could be built, I immediately flashed back to a Superman movie and his crystal palace hide-away. Thus, the Crystal Palace is the name I gave to this device. So, off I went to Delvie’s Plastics ( delviesplastics.com) and ordered 1/8”, 1/4”, and 1-1/2” acrylic rods. Delvie’s has the best prices for plastic I have seen.

However, because you have to buy the rods in quantity, this can be a kind of expensive purchase. The upside it that I have enough material to build many projects that require acrylic rods.

Next up, I had to figure out how to position the acrylic rods accurately over the LED matrix and support them well enough that they stood vertically. Being a wood worker, I decided to mill a piece of 3/4” hardwood with holes for each rod. This worked out well.

Finally, I built an enclosure for my breadboard out of 1/4” MDF and glued the drilled hard wood support on top, after carefully measuring so that the rods would be positioned accurately over their respective LEDs in the matrix. I also cut a square hole in the side of this enclosure for the USB power cable which connects to the Teensy 3.1 microcontroller to pass through. After gluing up the enclosure and doing some finish sanding to round over edges and remove any traces of glue, I painted the enclosure with black sparkle paint. This turned out to be a crude but effective enclosure (Figure 4).

You can watch the finished Crystal Palace in operation at www.youtube.com/embed/ mtjrkF2MqbM. If I were to build another one of these, I would do some things differently.

First, I would have made the breadboard square and not rectangular by mounting components on both sides of the board. I might even make a PCB (printed circuit board) instead of using point to point wiring next time.

Second, I would probably design the rod support and enclosure in a CAD system and 3D print it for much better positional accuracy.

Finally, I am thinking about making a bigger, better Crystal Palace by using a 32x32 RGB LED matrix like the one I used in my Light Appliance project (see N&V’s October 2014 issue).