Wiring a Pixel to an external SSR

It's possible to rewire a pixel to drive 3 channels of a DC SSR instead of the RGB LED. By so doing, you can gain control to other devices by using your normal pixel control data stream. A caveat is that in your sequencing, you need to remember which channels these devices are so you don't get confused. This example uses the Bullet or Square pixel using the WS2811 chip as the example and 5vdc power. Pixels that are powered via 12vdc may not work with this method unless the measured output voltage from the WS2811 chip doesn't exceed what the DC SSR can use as its control signal, which is usually 5vdc.

How a WS2811 Chip Works

First, let's understand how a WS2811 chip works by looking at the PCB for a typical square pixel.

Notice there are TWO ground pads, TWO 5v pads, a DI (data in) and a DO (data out) pad, and arrows that indicate the direction of the data flow. Also notice the four holes intended for a common anode RGB led (R, +, G, B). Data, power and ground comes into the chip, the chip lights the appropriate color of the LED, and extra data, power and ground goes back out to the next pixel in line.

A round bullet pixel has the same connection pads and the only difference is that they're on either side of the PCB instead of all on the bottom side.

Wiring Connections

Here's a look at how a bullet pixel is wired -- if you recall, 3 wires come into the pixel and 3 wires go out to the next one:

In place of the RGB Led, connect the WS2811 to a cat5 wire as follows:

How this works is that since a pixel requires three channels to light the LED, connecting the LED outputs to a CAT5 cable instead of to an LED and plugging that cable into a DC SSR gives you 3 channels of complete control, including dimming capability. Slick! Optionally, if the SSR needs a ground connection on pin 7 so that the SSR's status light pops on, solder the brown/white wire of the cat5 cable to the ground connection on either side of the WS2811 chip.

Does this also work with AC SSRs? Yes and no. Yes you will have simple on/off control with an AC SSR, but you won't have dimming ability.