Cabinets with BRAINS!

Ok, so I will confess that this is probably the third project I did as a woodworker and recovering nerd. As an engineer, much to the dismay of my wife, I always look for things that need solving, even if it isn’t a problem. This is one of those cases.
So how often have you been fumbling in the dark trying to pull a DVD out of your cabinet wishing that you could have independently lit (any color of the rainbow) shelves that would automatically sense when you put your hand in the shelf? I can easily count… one time… that that happened to me. So I decided to build a pair of these cabinets for my living room.

Woodworking stuff:
These are really simply constructed plywood frames with solid wood face frames, crown molding, and base trim that nicely accents my fireplace mantle. Since I was planning on having DVD’s in one cabinet and all my A/V equipment in the other, I added cord paths in the back of the cabinet and put the whole back panel on a piano hinge so I could easily hook everything up once I had it in the cabinet. There’s nothing too complex about the wood working part of it.
You may notice that I made the top entirely of solid wood with a mitered frame… a big no no. I didn’t know that at the time and amazingly with all the biscuits I put in it, it’s still staying together.
Now for the nerdy stuff (feel free to zone out now):
You wouldn’t know it, but each of the two cabinets I made have roughly 60 feet of wire in them. Each shelf has six RGB LED’s that are controlled via an Arduino microcontroller (see picture 3-5). Each shelf rests on adjustable shelf brackets (see picture 6) that are wired to power and three pulse width modulated (PWM) grounds. Each of the three PWM grounds controls how much current flows through a particular color of the LED, so I can control the color that the LED is putting out. With the way I have it programmed; it can be set to 1.68 million unique colors. Each shelf is independently controlled (segmented shelf brackets) so I can turn them on individually. The LED’s are hidden from view by the face frame as is all the wiring, which runs in a groove cut in the edges of the shelf to their respective contacts (the little screws visible in picture 5).

Now for the automatic lighting, each shelf has a infrared LED emitter and an infrared collector pointed at each other right behind the main cabinet face frame. Whenever anything obstructs the path between the two, I programmed the microcontroller to turn on it’s respective shelf. I also included a mode switch so I can run multiple programs. The shelves can either operate on the sensors or cycle in between various colors. I was going to implement a decibel meter (think vintage 80’s boom boxes with lights that turn on based on how loud the sound is) but I haven’t found an electronic solution to feed a good signal into the microcontrollers. Also, I got lazy.

Here is a video of the cabinets in action:

So, I feel like I have just touched the tip of the iceberg on what all was involved in these over-engineered cabinets – so feel free to ask if you have any questions.

-- Josh Lawson - Ankeny, Iowa