Light-emitting diodes, or LEDs, have made our world more colorful and energy efficient. We find them in use in everything from TVs and computer parts to industrial indicators. While these devices are usually hidden in plain sight, if you like creating colorful gadgets and electronics projects, the WS2812B programmable LED lights, aka the "NeoPixel," should be on your radar.
Understanding Programmable RGB LEDs
Measuring in at just 5mm x 5mm for each "5050" package, these units:
• Display red, green, and blue (with some similar units also bearing a dedicated white).
• Pass along a modified version of the control signal they receive to the next connected LED down the chain.
• Use that signal, in turn, to control the next LED, and the one after that, in a sequence stretching to over 1000 LEDs in some cases. Learn more about this amazing protocol itself here.
Each WS2812 isn't just one LED, but contains three discreet lights in one small package. The device also contains a nearly microscopic integrated circuit that takes in signals and passes the modified binary code along. You can see this little IC through the clear window that passes light through the device. With unaided eyes, it's so small that you might mistake it for some sort of manufacturing defect, or perhaps try to brush this "dark grain of sand" away!
Our human eyes won't tell you much about these units, so let's go on a photographic micro-tour of the WS2812B. I used a Canon DSLR and photo editing to zoom in on this device, then broke out my microscope to show more details. As I said, it's small.
WS2812B LED Overview
You can purchase this basic LED component on its own or add it to a configuration, such as programmable LED strips, rings, and individual breakouts, two of which you can see to the left of the first photo above. Configurations have their advantages, since you don't need to wire each unit on a strip individually. However, the "PCB dots" give you a lot of mounting flexibility. The strips also feature built-in capacitors, and the dots have both a capacitor and resistor added to support the main light.
As we mentioned, the 5050 LED's footprint is just 5mm x 5mm. In in the first image above, the grid is 1 x 1 inch (or 25.4 x 25.4mm), and the distance between the line and dot in the second photo is just half of that. So even though the photos are comparatively zoomed out, the shots are pretty tight. The second image shows a 5050 LED unit by itself, separated from its strip housing. While both are WS2812B LEDs and appear identical, there are some subtle differences in how they are made, which we'll illustrate in the microscope images further on in the article.
5050 LED: Specs & Macro View
If you focus in on the 5050 and its light surface, you'll get a better sense of what's inside. In the first image, you can see the rectangular control chip situated in the middle of a reflective panel towards the bottom. The control chip reaches out to three LEDs with tiny wires, two of which reside on one panel, with the third resting on another.
The second image shows a slightly more zoomed-out view of a different WS2812B LED, which has all three LEDs situated on one panel. These devices underwent a timing revision in 2017. The strips I used are of unknown vintage, and I purchased the PCB dot within the year, so it's possible the component's physical aspects went through a slight modification as well.
At one point, I assumed that each panel corresponded to a different color LED, or even that they were the LEDs. While my assumption was incorrect, other users probably made the same mistake, so I don't feel too foolish.
Examining the LED ChipBy zooming in even further, we can see a better view of the chip that controls everything. Scaling the images I captured for this article, the approximate dimensions of this component are just .8mm x 1mmm, which leaves very little assembly wiggle-room. Nonetheless, these devices are manufactured and sold by the millions, with few reported defects.
With this sub-square millimeter area, the chip can independently control three LEDs as well as read, use, and pass along color data when necessary. This type of functionality is something we mostly take for granted, but delving into how these components work is a reminder of just how amazing today's electrical technology is.
The WS2812B LED Lit Up
The business end of these chips is, of course, the onboard LEDs. You can see their "off" arrangement in the first image, while the red, green, and blue colors feature prominently in the second. Note that the "off" image corresponds to the type with every LED on a single panel, while the other has green/red on one panel and blue on the other. Also, the LEDs were set at their greatest brightness (255) to avoid the scan lines that show up when these devices quickly blink on and off.
External Shots of the WS2812B 5050 RGB LED
Besides the WS2812B LED itself, the supporting hardware is fascinating to observe up-close. Here we have the PCB LED dot's solder connections and external solder pads, along with a resistor and capacitor added externally.
In the first image, you can see an up-close view of the strip's protective rubber surface. Note that not all strips provide this protective exterior, so this may or may not be ideal for your application. The second shot is an LED unit ripped from its resting place. We could probably reuse it in its raw form if necessary.
Sub-255 Brightness LEDs
If you were wondering about the image lines that show up when the LEDs aren't at full brightness, here's what they look like. Interestingly, these lines appear to be white, not black, which might correspond to the image trying to compensate for the intermittent darkness, then being washed out by the full power LEDs. I'm certainly not an expert in microscopic photography — I was shocked it was able to capture the LEDs on at all — so I'd welcome readers' input as well!