New test of E21A quadtrix. My second reflow attempt this time. Change to the test setup included an addition of a lux meter, though not a great one and not mounted well, but it did provide some insight into peak output.
Below is an image compiled by Clemence showing all of the IR images taken in the test, as well as some plots of the data taken. Emitter setup was 2S2P. Please note with the Lux data that I did not turn off the room lighting, so it started out at non-zero. The setup also means that the number could be changed quite a bit just by moving around the room, so they are very approximate.
On this test I went beyond the 150C phosphor temp based on lux meter readings. Peak output occurred at 5.5A!
Phosphor temps were imaged up to 5A, at 5.5A I unfortunately messed up and didn’t save an image, but phosphor temps were bouncing around the 200C mark. At 6A I did not take an image as I saw the temps at 210 and rising and the lux meter was starting to drop fast, so the test was immediately shut down.
This was the result of that 6A run, slightly browned edges right where the two hot spots are between the emitters. If i hadn’t shut it down quickly I predict it would have ended up like the emitters Clemence shows in the 1st post. This also proves the photon absorption, and I am fairly confident the Rev.2 boards with larger gaps between emitters will be capable of even higher output.
After this I tested a hypothesis from an observation of my last test. I re-ran the emitter at 4A for about 5 minutes, and then ran the full sweep from 0.5A to 4A again, with only about 30s per step, just to check Lux. Lux was basically unchanged, I could move my arm and change the number more. Visually the browning is now gone too. Not sure what causes this phenomena, but Clemence has seen the original images with their attached timestamp data and can verify.
It will be interesting to see if more people push these LEDs and also observe this strange healing effect of the phosphors. Will also be interesting to see how the new gapped MCPCB layout changes performance and the hot spots.