LED Pixels

Technicolor Pixels

The most important elements of our system are the LED pixels highlighting key architectural features of the house. These run along the edges of the roof, along the roof ridge lines, around the windows and garage door, and along key vertical features.

For the house pixels, we purchased from Ray Wu’s store on aliexpress.com. All of the pixels are of the “technicolor” form factor (wires come out of the sides of the pixel body rather than the bottom) and came in 50 pixel strings spaced with 10cm long wires between pixels with weatherproof connectors on each end. They are 12V DC power, use the WS2811 chip internally, and are IP68 (weatherproof). The pixels used along the roof have optional faceted C9 diffuser bulbs that screw onto the pixel; the pixels on the face of the house do not have the diffuser bulb.

Technicolor pixel without a diffuser bulb. Dimensions are 1 7/16″ wide x 1″ deep x 1 1/8″ high. The distance between the indentations for the zip ties is 1 1/8″ on center.
Technicolor pixel with the C9 diffuser bulb attached. With the bulb, the total height of the pixel is 2 5/8″.

The C9 diffuser bulbs are made of a very fragile plastic and the flange of the bulb where it screws into the pixel breaks very easily. Take care when working with them and consider ordering some extra diffuser bulbs (Ray Wu sells these separately) to have on hand. Fortunately, even when the flange is broken, the bulbs will still often times screw into the pixel sufficiently to be used. There were only one or two that we broke so severely that they were unusable.

These pixels come from China and thus shipping can be a significant portion of the cost. There also does not seem to be any significant bulk discount with respect to shipping as more strings are ordered. Also note that shipping is more costly when ordering pixels with the C9 bulbs than those without because they take up more space.

The pixels have three wires (power, ground, and data). They use a protocol based on the ws2811 chip where each pixel takes in the data packet, strips off the first three values (red, green, and blue levels), and then republishes the remainder of the packet for the next pixel downstream. In essence, each pixel always just thinks it is the first one in the string. As such, multiple strands can be joined together, strands can be cut, individual pixels can be swapped out, etc. without any issue.

Out of the 1200 pixels we used in 2016, there were 5-10 pixels that did not behave properly and had to be swapped out. We had about 20 extra pixels on hand, though we should have likely purchased an extra string just to be safe. Pixels failed in different ways, but the most common was that one of the three primary colors would stop functioning (e.g., a pixel loses the ability to do green and thus displays red when instructed to make yellow and displays pinkish purple when instructed to make white).

Since a 50 pixel strand was too long for our use, we did a lot of cutting of strands into smaller sections and thus needed extra 3-wire weatherproof connectors to attach to the shortened strands. These are pretty cheap and seem to work quite well at connecting to strands together without water getting inside. The manufacturing quality isn’t always stellar but a utility knife to trim away any excess plastic from the molding process solved the problem for us. NOTE: later on we ordered some additional 3-pin connectors and were dismayed to find that they are not identical. They look the same, but the form factor is a bit different and are thus not interchangeable. If we use them, we will have to keep track of which connections have the original type and which have the new smaller type; better to avoid this hassle altogether and verify you are ordering exactly the right connector.

The actual dimension of the pixel is as follows. See Mounting Pixels on the House for details about how we spaced these and attached them to the house.

Not sure how long these links will last but these are the exact items we ordered.

Without diffuser bulb: https://www.aliexpress.com/item/NEW-50nodes-DC12V-WS2811-LED-C9-technicolor-pixel-IP68-with-epoxy-resin-filled-transparent-PC-material/32306486315.html

With diffuser bulb: https://www.aliexpress.com/item/NEW-50nodes-DC12V-WS2811-LED-technicolor-pixel-IP68-with-epoxy-resin-filled-transparent-PC-material-and/32306647583.html

Extra weatherproof connector pigtails: https://www.aliexpress.com/item/20cm-long-each-3-Core-White-Waterproof-pigtail-male-and-female-male-connector-s-diameter-13/813582127.html

Bullet Pixels

The light bulb rails that line our driveway use a different form factor of pixel called a bullet. Fundamentally, they behave the same as the technicolor pixels but just have a different shape with wires coming out the bottom of each pixel instead of the sides.

The dimensions of our bullet pixels are below.

Here are the bullet pixels we used for the light bulb rails. The connecting wires are 4″ casing to casing so we had to solder in some extra wire.

This is the bullet pixel we ordered: https://www.aliexpress.com/item/18AWG-wire-100pcs-string-DC12V-12mm-WS2811-addressable-RGB-led-smart-pixel-node-with-all-WHITE/32598220222.html

LED Strips

Starting in 2017, we introduced several new elements in our display that use adhesive LED strips. These are cheaper than the other types of pixels and are particularly great for applications where you don’t want the actual light source to be seen. The stereotypical example is a leaping light arch (which we actually don’t have) where the LED strip is inside of a translucent tube.

We use 12V LED strips for our window light boxes and our snowmen. We use 5V LED strips for the seven-segment displays on the garage door. Due to the nature of how voltage drops across an LED, all 12V LED strips seem to be configured such that each ws2811 chip actually controls 3 adjacent LEDs. From a control perspective, the three LEDs behave as a single pixel, though they are separated in space. The strip can be cut after every block of 3 LEDs, but not within a block. This arrangement is fine for many applications but was not satisfactory for use on the garage door since those pixels are intended to be viewed directly and we wanted true individual control.

Enter the 5V ws2812 pixel. The protocol is identical to the ws2811 but the ws2812 is a combined package of the control chip and the LED. Since it is running on 5V, a single LED is sufficient from a voltage drop perspective and thus the strip can be cut after any LED. This individual control is necessary for our seven-segment displays and would certainly be needed in a pixel screen arrangement.

The strips also come in 3 levels of IP (weatherproofing) rating: IP30, IP65, an IP67. For indoor or otherwise weather-protected usage, definitely go with the IP30. They are easy to work with since the metal terminals are exposed…which is why they are also very bad for locations that could get wet. For our outdoor usages, we purchased IP65 strips, which have a silicone coating molded directly onto the strip to protect it. This works very well, but is a pain in the butt when you need to cut a strip and solder on connectors or wires since you first have to carefully cut and remove a portion of the silicone. We intentionally stayed way from the IP67 pixels, which are essentially the IP30 strip tucked into a silicone sleeve. From what we have seen, they just don’t look as good as the IP65, though we imagine they are easier to work with.

All of the LED strips we purchased use a non-waterproof connector, though at least one of the strips had male and female reversed from the others. They also all had barrel power connectors on either end for the purposes of power injection, though we have typically removed or ignored those connectors and instead used more of the standard strip connectors when doing power injection. See the detailed pages on the garage door seven-segment displays and window light boxes for more info on the exact wiring.

These are the connectors that come on the LED pixel strips. RED=power, GREEN=data, WHITE=ground

The other decision required when purchasing pixel strips is the density. 30 LEDs (10 pixels) per meter seems to be the norm for 12V pixels, though there are denser options. We purchased a 20 pixel/meter strip for comparison sake that is now in use in our bedroom as part of a DIY wakeup light (see that project on GitHub). Our light boxes and snowmen are using the 10 pixels/meter strips and those are satisfactory. The garage door seven-segment displays have the same density but are technically 30 pixels/meter since every LED is its own pixel.

These are the pixel strips we used for the window light boxes. Note the lack of any weatherproofing. Each set of 3 LEDs makes up a single pixel and are controlled together by a single IC (which you see in black). You can cut the strips at the copper pads you can see at either end of a pixel.
These are the strips we used for the LED snowmen. They are the same spacing as those used for the light boxes but have the molded silicone coating to make them weatherproof. It is kind of a pain to cut away the coating where needed to solder on wires, but it’s better than having to weatherproof them yourself.
These are the 5V pixel strips we used for the garage door seven-segment displays. Because they are 5V, each LED is its own pixel. The IC controlling the pixel is actually part of the LED package. These have the same weatherproof coating as those we used for the snowmen.
For comparison, this is the 20 pixels/meter 12V strip we purchased. We ended up using this in a different wakeup light project for our bedroom. Fundamentally, these pixels work the same as the less dense strips but just cost a bit more due to the higher quantity of pixels.

We should also note that there seems to be little consistency with the ordering of red, green, and blue for commanding the various types of pixels. Even amongst our pixel strips, the ordering of the three channels differs, but this is easily remediable through configuration in the pixel controllers. We have yet to see documentation telling of the ordering and this is where the test functions on a pixel controller come in handy. We simply set the pixels to one of the primary colors and checked to see what primary color the strip actually turned.

With the confidence of a year of pixel lighting under our belts, we expanded our list of suppliers when purchasing LED strips and found many options for a reasonable price with free shipping! The shipping still takes a while since it’s coming from China but at least we aren’t paying 30+% extra for it like we did with the technicolor pixels. Aliexpress has a ton of sellers and we have not had any issues with the ones we have used. Our pixels have always arrived as advertised and ahead of the admittedly worst-case shipping estimated times.

Here are the various pixel strips we ordered from Aliexpress. All of these have been satisfactory and we have no complaints. UPDATE: we actually do have a complaint with the 5V pixels we purchased but it is hard to articulate exactly what the issue is. See the bottom of the Garage Door Seven-Segment Display page for the saga.