Well I just bit the bullet and sliced my XHP50.2 and I’m absolutely ecstatic! No green and 196k lux at just over a meter. Not bad for huge die in a small reflector! I did as was done in the posted link and scraped as much of the excess phosphor as I dared (~1mm left surrounding the dies).
Also I thought I would add, the dome on these emitters is completely clear, the yellow appearance I can only assume is a result of the excessive amounts of phosphor covering the whole chip.
The gains may not be as dramatic as with the older gen emitters but gains are still gains. As a novice modder I’m in no position to give advice, but if I can successfully slice one of these with good results then I feel the pros among us should not give up on them.
The host is a convoy C8 with smooth reflector and pre slice measurement was around 92k lux, it’s over 100% gain but I think part of the jump was due to the fact the reflector was a little out of focus before the slice.
I will hopefully upload a picture shortly.
Lux meter is ‘max meter’ branded, cost around £20. I set the meter against a wall and point the light at it and took the measurement after 15-20 seconds. I can’t wait to the 30 second mark as it drops out of turbo at 30 seconds due to massive heat. The host can’t dissipate the heat generated by a DD 50.2 running at ~10A fast enough
I think the next question is at what distance did you measure the light intensity, with a C8 size reflector you want at least 4 or 5 meters to get anything correct.
Just from my experience and reading others’ experience I can guess about what an LED will do in a given reflector. ~190Kcd is what some of the best emitters will do (the emitters with the highest luminance, like dedomed XPG2) in a C8. From my experience with the sliced XHP50 I know it has significantly less throw than a dedomed XPG2, partly due to the gaps between the dies. From what I have seen the new style of LEDs from cree (XPL2, XPG3, XHP50.2) have even less throw than the old versions. So this is what makes me suspect your results. But, I haven’t actually seen any measurements for the XHP50.2, so I could be wrong.
What distance are you measuring from and what math do you do to get to the candela number?
Flash max: the LED is an 80+ CRI 3000k stock. I haven’t noticed a considerable tint shift and i stupidly didn’t take a pre photo for comparison.
Light bringer: I’m not sure what you mean by distributed phosphor. I’m pretty new to flashlights and modding but I like to dive into things headfirst at the deep end with a lead helmet.
I’m using 2 VTC5’s in series, in direct drive I’m getting ~10A at tail cap.
How do I convert from lux to cd? I just used rapidtables converter and it’s saying that 196k lux is 259kcd.
This is all new to me so I’m probably in need of some educating.
To convert lux to kcd you need to know the exact distance. For example I use 5 meters (the longer the better), so to compute kcd:
meter reading * distance * distance (distance squared in meters)
If you measure in true lux (typically I use the 10X setting), then for 5 meters multiple by 25 to get cd. kcd is 1,000 cd. We usually quote kcd - no need to add decimal digits - our meters ain't that accurate
Regular “old” LEDs would have a phosphor coating right on the chip itself, which is why white LEDs look yellow.
“Remote phosphor” would be a plain blue LED, but the phosphor is off the LED, like screw-base lightbulbs with blue LEDs but yellow-looking plastic “shells” around it that convert blue into multi-spectrum “white” light. On an LED it might be a hollow silicone dome but with the phosphor coating on the inside of the dome. Dunno any that do that, though.
“Distributed phosphor” would be having phosphor powder/flakes/whatever being mixed into the silicone itself and then formed into a dome or coating.
If you look at a G2, you can actually see the chip through the clear dome. The G3 looks like it’s got an orange dome itself on top of the LED.
I don’t have any G3s (only ordered some G2s for the first time), so I’m only going by the pix I can find online, not having an actual chip to eyeball.
Ahhh, interesting stuff! I can currently only speak for the 50.2 but the dimes is definitely clear. The bits I sliced off are definitely 100% clear. As said I think the ‘yellow dome’ effect is caused by the fact that the entire visible surface of the LED is coated. I have a few G3’s on the way for experimenting. I will let you know my finding.
I will also go away and take some more readings at greater distances to give more accuracy and also take some readings for my M2 and TN4A as comparison.
I’ve been slicing and dicing a number of these new cree LEDs and so far am reasonably liking the results, unfortunately not the same throw as certain other older LEDs but for the lumens pretty respectable. For a comparison, all in a Jaxman Z1, XP-L2 ~190kcd, XP-G3 ~200kcd, XHP-50.2 ~190kcd. Although compared to the 400+kcd the SoH does in the same host they are not that impressive.
