I just did some lumens measurements in my Sputnik, (Light Integration Sphere) and got some impressive results from the Samsung LH351D 4000K High-CRI LEDs over the Cree XP-L 3000K LEDs.
The Lux-sphere i have is modified with a special adjustable diffuser plate for the sensor, so it can also measure light sources from the center of the sphere along with flashlights from the top, (flood-type lanterns placed inside the sphere as opposed to flashlights set on top with a directional beam.)
(As shown below with the BLF V2 Prototype placed inside the sphere for output measuring)
Below is a photo showing two new LH351 4000K LEDs flowed onto the Lantern (Q8) PCB, (the loose LED to the left in the photo is one of the two XP-L 3000K emitters removed after the first test)
Here is what i found: > The LH351 4000K High-CRI emitters, measured to be more efficient, and have a higher output than the XP-L 3000K at the same current & test perimeters.
- (two) Cree XP-L 3000K ————————— / 630 lumens / 1.09 amps / High-mode ( maximum of the 5-mode group on 3-7135 AMC chips)
(two) Samsung LH351 4000K High-CRI——/ 745 lumens / 1.07 amps / High-mode ( maximum of the 5-mode group on 3-7135 AMC chips)
I did notice a slight tint shift on the Samsung emitters over the High-CRI Nichia 219 series, but the LH351s sem to be much more efficient and capable of higher outputs.
Next up is to test with four LH35 4000K High-CRI emitters, to see the difference from using two of them.
In comparison, the V2 prototype appears very close to the output along side a factory 800-lumen Noma LED 11-Watt AC light bulb. Tomorrow i will test the lantern in the sphere in comparison to the 11-watt 120-volt household bulb to see how close the factory specified 800 lumens is to the lantern. :sunglasses:
Below, is a photo of how i replaced the original Q8 Narsil driver’s FET for the V2 Lantern prototype with AMC 7135 regulators. I used a dead (stripped) 105C PCB, and jumpered it into the Q8 dribver after i removed the FET. This gives me the ability to modify the driver from one up to eight 7135s, ( but i will likely keep it at either three or four AMC regulator chips as for lantern use full amp current is not needed to achieve a good balance of output versus run times. (for lanterns the run times are very important as they will be used in a manner where they are run for many hours at a time continuously as opposed to a flashlight.) considering that the near perfect Narsil firmware offers so many mode options, using up to four 7135 chips may be a practical idea, for those times that close to 1000-lumens may be needed if we can control the heat safely for longer periods or running in such a small size lantern as the BLF Lantern will be. I estimated that with four 7135s, the draw amp load on the cells would be roughly 1.4 amps average on maximum mode, on four good 3600mah cells, so in theory & past testing i did that should still be able to give 8+ hours of run time at between 900 to 1000 lumens output… based on my past run time tests of modified lanterns using Li-Ion cells, (as long as we can somehow manage the heat from the head of the lantern at those sustained outputs for continuous running.
- one of the two LH351 4000K LEDs flickered and went dead for some reason when running for past 2 hours at the 1.07 amps combined. I will investigate to see why it went out tomorrow.
*So after further tests and checking on the one LED that flickered & went out, its definitely a dead emitter… Its my luck to get a bad LH351 4000K for the lantern testing.
I have flowed on the three good ones, but can’t do a test of the four compared to two LEDs until i can fins another one*
EDIT I discovered when i gently push in on the LED dome with a pair of tweezers, the LED comes on. So it appears the internal bond wire came loose. I have a short video fo the LED flickering, but don;t know how to post videos here without using Youtube.
As of right now I am in need of a replacement LH351D 4000K High-CRI emitter to test the lantern using four to compare that configuration over the two-LED set up. DO any one have any sources where i could get one?
Looks like you’re good for now, but Digi-Key actually has 8 varieties in-stock with no minimum. Different CRI’s (70-80) and CCT’s (3000-5700) available. Link