In the course of my investigation of LEDs claiming to be WS2812Bs, I created a review on Amazon for Mokungit’s 93 LED ring device – because unlike other devices from other companies, theirs actually had what appear to be normal WS2812B LEDs! This post contains much of that original review.
Edit: Then that review got rejected, apparently because I mentioned that inferior LEDs exist. Be very, very careful buying anything that claims to use WS2812B LEDs from Amazon or eBay because getting reliable information is increasingly difficult.
I’ve been on the hunt for a good 16×16 panel of WS2812B LEDs. Since Mokungit didn’t have any available on Amazon for a while, I ordered one from another seller on Amazon (and later, one from ebay). Problems were immediately evident in the one from the other Amazon seller – particularly, the blue die on one LED refused to work until the other colors warmed up the device (or you pressed on it), and all the LEDs flickered at color #0F0F0F or less (pronounced at #010101). Unacceptable!
Then I took a closer look at the LED (since I wondered if the flaw was visible). Normally a WS2812B has three LED elements, a chip, and fine wires internally connecting them together, then encapsulated in a clear resin or epoxy to ensure corrosion resistance. The WS2812B LEDs from this Mokungit ring matched exactly what I’d expect to see: the WS2811 driver chip on one pad, the red and green LED bies on another pad, and the blue LED die on the third pad. Why the separation? I believe it’s because the blue LED dissipates more power and thus it’s optimal to have it on its own separate pad.
This design distinguishes the WS2812B from what appear to be knockoffs, which instead have the driver chip on one pad and the three LED substrates all crowded together on the adjoining pad. My experience is that these are inferior overall.
The photos above show the two different devices. The large dark rectangle is the driver chip, and on the normal WS2812B (photo taken of an LED on the Mokungit ring I bought) we see the blue LED die (a small white rectangle) a bit up and right of center. The other photos, of the knockoff/inferior device found elsewhere, shows all three LED dies on the lower pad. (The bonding pattern isn’t even the same on the chip die itself which makes me wonder if the WS2811 chip is a knockoff too – that’d explain the odd flicker at low settings.)
Note: the devices under test had plenty of clean power – the LED ring with the genuine devices was flicker free from color #010101 forward. The 16×16 panel of the “fakes”? They flickered like mad until you got over #0F0F0F or so.
Now you know how to tell good from garbage when it comes to WS2812B LEDs and the products using them!
Upshot: The 16×16 panel I wanted from Mokungit directly is on Amazon again! I ordered it and will update this post once it arrives. Fingers crossed that it has the quality WS2812B LEDs on it like their other one did. If all goes well, the junk ones are all going back from whence they came (along with the spare junk LEDs I got).
For more info on identifying inferior WS2812Bs, see this article on Josh.com as well as the comments (where I started discussing this recently).