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Touch-sensitive Nightstand

Demonstration


Ever fumbled for the lights at night, or needed just enough light to walk around the room? How about searching through a drawer for a flashlight in pitch dark? This nightstand solves all those problems and more by adding some lights and touch controls to a nightstand:
  • Tap any touch pad once to turn on a night light that is directed toward the floor
  • Tap any touch pad twice to turn on the lamp (or any other 120V device)
  • Open the drawer and the contents are illuminated
  • Night light and drawer illumination work even during power outages thanks to a battery backup.
  • Configure the color of the lights by touching a pad a holding. (Left = Red, Center = Green, Right = Blue). The colors will cycle intensity until you let go. 
  • Colors are independent for the night light and drawer, and their values are stored in non-volatile memory.
The finished product has the following unconventional parts:
  • Three capacitive touch pads (one for each side except the back)
  • Two RGB LEDs (one for the bottom, and one for the drawer)
  • Magnetic reed switch for drawer sensing
  • PowerSSR Tail for lamp control (totally silent)
  • Arduino FIO to run all the components
  • 1000 mAh Lithium Ion Battery for backup power
This project started with a delivery of genuine Mahogany from Woodworker's Source. Normally I like to buy locally, but unfortunately they didn't carry Mahogany and their Sapele selection didn't include anything thick enough for the legs. Everything arrived very nicely packed and the wood itself was beautiful. 

I built the nightstand itself using mostly conventional methods. The primary joining was done using my Dowelmax, but the drawer utilizes dovetails that I cut on my CNC Mill. The legs are tapered using a Rockler taper jig. I used Blum self-closing undermount slides to complete the "high-tech" feel of the nightstand.

I was concerned about wood movement for the bottom shelf and I wanted it attached to the legs (rather than floating), so I made the shelf using some Sapele plywood with 1/8" strips of Mahogany as a border. To attach the legs I made 45 degree notches in both the legs and the shelf to minimize any alignment problems and give plenty of glue surface area. The notches on the legs were also cut on the CNC using a V block to hold it at the proper angle. The top is attached with screws in the back and table top fasteners everywhere else to allow for movement.

After the woodworking was done then it really started getting interesting. I cut some custom touch pads using the CNC Mill. Copper was cleared from the edge so that the entire surface could be covered with Kapton tape to avoid any static electricity issues. Then matching pockets were cut into the top of the nightstand so the touchpads would sit flush with the rest of the surface. At that point I applied my finish. I chose a mixture of cherry and java gel coats from General Finishes (this piece was a gift, so I tried to match their other nightstand) followed by General Finishes High Performance Satin. I left the drawer box natural (just the clear coat) to create some contrast. After finishing I created a rough version of the electronics on a breadboard using the Arduino. Finally, I soldered the final circuit and attached it under the top using a plastic enclosure. Here are a few photos that I took during and after construction:








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