Mood light coaster

Yes, that’s what you get if you throw some laser-cut acrylic sheets (via Ponoko or Formulor) and a LED board into one big pot and stir it vigorously.

Parts used:

  • one of my recent LED ring boards – >>Circuit boards / DIY kits / fully built<<
  • 2x battery clips for AA cells
  • adjustable dc/dc boost converter from Pololu
  • analog reflection IR sensor from Pololu as well
  • wire, headers, screws, washers…


  • Detection of objects that are on top of it (e.g. glasses)
  • RGB effects – of course! (runs with a slightly modified ShiftPWM library)
  • efficiently drain old AA cells
  • automatically calibrates the detection threshold when turned on

The only real issue it has is that it doesn’t like the presence of incandescent light bulbs. These wretched things really are IR flood-lights and easily saturate the photo-transistor. You won’t have any trouble with CFL / LED lights though ;-)


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