Planning & Power

My dining room has three Japanese tatami mats centered on the subfloor, creating a 3-4" trench around the perimeter.  The trench is about 2" deep and butts up on the 4th-wall side against the raised bamboo flooring in my living room.  

This design would also work really well to line the edges of a hallway or walkway, though for outdoor applications the controller and power supply would need to be weather-proofed.

I looked around for glass pebbles in bulk, and found the best deals online sold as "fireplace glass".  These appear to be mostly used for diffusion materials in classy restaurants' outdoor gas fire pits. 

They come in a good range of colors and a couple different shapes.  The rounder pebbles seem to be much kinder to bare feet, so I went with that shape.  I decided on 80% aqua blue with a few darker green pebbles mixed in for contrast.  

They come in 10 pound bags.  For my project I ended up using 10 bags of blue glass and 3 bags of green.  This filled a trench that was approximately 4" wide and 2" deep, and about 9.5m long.  

LED Density

Adafruit sells Dotstar strips in 30/m, 60/m or 144/m densities.  The higher density strips have a couple advantages:

  • They are brighter overall: more lights per meter packs more of a punch
  • The animations running on the lights look buttery smooth and scintillating.  Mmm.

They also have a couple of drawbacks: 

  • They cost more
  • They need a lot more power
  • You may run into mysterious limits with your microcontroller -- it can't always drive thousands of pixels

I wasn't sure which way to go, so I set up three test strands, each about 1/2m long, and loaded the same animations on all three.  Here is the result.

The 144/m lights do indeed look brighter and buttery-smooth.  However, they cost 4x as much as the 30/m, and well.. they just don't look 4x better.  That and the worry about heat and power and programming limits ruled these right out for me. 

I thought there would be more difference between the 60/m and 30/m but they look almost identical.  The 30/m are slightly dimmer but are bright enough to look beautiful even during the daytime, and at night they look incredible.  The glass pebbles do a really good job of diffusing the pixels and spreading the light around.  

Any of the three varieties will look beautiful.  If you choose to go with the buttery-smooth 144/m, you may want to inject power between each of your strips.

Neopixels vs Dotstars

You could use either Neopixels or Dotstars for this project.  Neopixels are a little less expensive and require one less wire to hook up.  If you like this project as-is, either type of LED will work fine with just a small change to the code.

I chose to go with Dotstars because then I've got a little more freedom available in terms of coding.  I kept this project fairly simple, but someday I may decide I want to add an IR remote control, or do fancy home automation over Wifi or Bluetooth.  The Dotstar LEDs have a separate clock line, which more-or-less means you can interrupt an animation with a change command much more easily.  I've run into brick walls in my coding when I tried to get fancy with Neopixels in the past, and spending the extra $10 for Dotstars up-front may keep me from a lot of frustration down the line.

Power

These strips want 5v power.   Using a lower voltage will give you flickering and brown-outs, and using a higher voltage will burn out your LEDs and controller.  Stick with 5v!

The amperage requirement will change depending on how many LEDs you have. Head over to the Neopixel Uberguide to learn more about power requirements.  For up to around 300 LEDs I found the 5v 10A power supply to be totally sufficient.

This guide was first published on Aug 16, 2017. It was last updated on Sep 17, 2018. This page (Planning & Power) was last updated on Aug 16, 2017.