Matrix Display 20×16

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

Two of these signs were built to place on either side of the garage door. The signs were built using WS2812B pixels with 30 pixels per meter. The pixel strips were cut into 16 pieces that were 20 pixels long for a total of 320 pixels. So this sign takes just two universes. I live in California and these were placed under the eves, so I used Masonite for the foundation. Using a table saw I cut dado groves in the wood to inlay the pixel strips. I wanted to ensure that my lines of pixels were straight. The strips come adhesive backed, but I used additional RTV to hold them in the grooves as shown below.

Pixels in Grooves

The hard part of this is to figure out how to lay them out, so that they can be easily controlled. I like Xlights/Nutcracker because it provides a picture of how the software expects the pixels to appear. This is shown below, where there are two universes of pixels (light blue/green) with 160 pixels in each. So in the model tab of Nutcracker, this is a horizontal matrix with two strings of 160 RGB nodes. There are eight strands to each of the strings.

Node Layout

To keep the continuity of the sets of strings, I looped signal and ground at nodes 20/21, 40/41, 60/61, etc. There were two pixel control lines as you can see from the back of the display. These control lines were inserted at node positions 1 and 161. I injected power on all 16 strips along the left side of the display, which you can also see in the back of the picture (nodes 1, 40, 41, 80, 81, etc.)

From a grounding perspective this is all wrong, because I created multiple power and ground returns to the single power supply. The ideal solution would be to inject the power only at nodes 1 and 161 , where you also tie the controller ground. This creates no power or ground loops. Then if you need additional power, you would use another power supply to inject power on down the length of the strip. So from a power perspective it is better to power a sign will many small power supplies rather than one large one.

This size sign is attractive because of the cost for the components.

  • 320 pixels ($6 per 30) $64
  • 5Vdc 100W power supply $20
  • Power Cord $3.40
  • Receiver card $7.00
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