LG high CRI LED E2L flashlight-maybe this LED is unknow to everyone..

Don’t recall the ratings, but you’d need to make sure the Vf for the 2 types is a nearly exact match, else the 2 with the lower Vf will be almost fully on and the 2 with the higher Vf will be pretty much off (applied voltage below Vγ).

Unless you run them in series. That reason is why most of my lights going forward will be boost driver based.

If LEDs wired in parallel, but I was thinking of this by wiring them up in series with a boost driver…but really don’t know as I didn’t test this yet.

You are correct Tally-Ho, they would work well in series, I have a few lights now with highly mixed Vf emitters in series, and I really like the freedom to mix tints however I see fit without worrying about mixing voltages too.

Either way, i expected it to be a (more or less) safe bet, and maybe not as nice as Nichia, but good none the less.
I’m sure others feel the same disappointment.
It would have been great to have a high power high CRI LED, for applications where the Nichia 219 is just a bit too low power (and gets too hot).

O well…

I did a voltage+output test on this LG H35F0 from Jaxman but am slow in posting it, but looking at the numbers: when voltage is compared to the 219C: up to and around 3A it is almost identical (3.27V) and when current goes further up the H35F0 curve is a bit steeper than the 219C curve.

So also when connected in parallel they should go together fairly well.

Jaxman should start to sell minus green filters :smiley:

I wouldn’t have thought to this by myself if I hadn’t seen people mentionning and doing this on BLF. I was checking my bookmarks a few minutes ago and saw that you were the one I seen doing this recently in Clemence’s thread. Sorry I didn’t remember that it was you :person_facepalming: Thanks a lot for the idea. :wink:

Thanks for the info djozz. It’s always nice to learn something from one of my BLF’s heroes.

That wouldn’t help with the big tint shift in the beam though.

I’m going to try a mix with 90CRI 4000K XP-L2’s, or XP-G3’s, they have sort of the opposite: blue-ish hotspot with yellow corona. And as a third led a warm Nichia, for some red in the beam.

Found this pdf.
Link: http://www.prognostics.umd.edu/calcepapers/Light_emitting_diode_reliability_review.pdf

The ways to drive the current to light up LEDs are divided into
pulsed width modulation (PWM) dimming and analog dimming
(amplitude dimming) [49]. Analog dimming involves changing
the constant current through the LED by adjusting the sense volt-
age. Analog dimming does not generate additional switching noise
in the LED lighting system and has higher efficacy as current levels
decrease.

*The dominant wavelength varies with LED current due to
band filling and the quantum-confined Stark effect (QCSE), so some
color shift is to be expected when using analog dimming.*

On the
other hand, PWM dimming involves a desired LED current and
can turn the LED on and off at speeds faster than the human eye
can detect. The color of LEDs can be controlled by using PWM dim-
ming if the junction temperature is controlled, since the dominant
wavelength changes due to the junction temperature. The input
supply needs to be filtered properly to accommodate high input
current transients. The efficiency of PWM dimming is lower than
that of analog dimming [49]. PWM dimming technology is catego-
rized into enable dimming, series dimming, and shunt dimming.
Enable dimming produces PWM current by turning on and off
the current. Enable dimming is easy to implement, but typically
shows slow current transitions. Series dimming uses the series
field effect transistor (FET) to generate PWM current with current
transition. Output voltage can overshoot when using series dim-
ming. Shunt dimming utilizes shunt FET to generate the PWM sig-
nal with super-fast current transitions. The drawback of shunt
dimming is that power is dissipated in the shunt FET. If it is neces-
sary to drive different types of LEDs having different forward volt-
ages, multi-boost or buck current mode control is used due to the
benefit of independent multiple power stages. PWM dimming con-
trol is good for driving uniform LEDs with the same color and for-
ward voltages [48]. Although, the reliability and performance of
these control circuits are critical to the success of LED lighting sys-
tems, this paper covers only LED packages.

.

Maybe that’s why it looks green?
I read in the dedoom sst-40 thread (I think) and someone used 2 different drivers and one of the driver made the light looking really green if i remember correctly.

Edit: Can’t seem to get bold text working…

Using a constant current power supply improves the tint, but only marginally. It is still duv 0.0100 so very green.

Btw, here’s the LG and a Nichia SW40 combined. Nichia output a bit higher and the LG just supports it. At similar levels the beam is too green and CRI is much worse than with just the Nichia.

Here’s only the Nichia. No big change in overall indexes except that R9 is better without the LG and some turquoise and blues are a bit better with. I see no practical reason to combine them.

Very interresting tests maukka.
Thanks a lot for having taken the time to do this. :+1:

Wow, these LEDs are tough to use…
Bad tint shift, even in most frosted or pebbled TIR optics.
Haven’t tried the triple set up yet though.

On a positive note, they’re better than an average XM-L2 regarding colour rendition and tint.
They’re less bright though.

So i have one in a Nitecore HC30 now, but i had to try 3 different TIR optics before it was without tint shift.
I use a (i think) 45° TIR with relatively high pebbles now.
I can imagine the nightmare it will produce with an aluminium reflector…

Hmm. Green color have the wavelength between 495–570 nm.

Electroplate the reflector somehow with copper to reduce the reflectance of green with around 40%?
But that would include alot of blue color reduction to.
.

Are this LG LEDs similar to Samsung LH351D?

Just almost bought Z1 XHP50.2 shorty. But after adding shipping to Poland it’s about $70, a bit beyond my budget. :frowning:

If nobody knows, I will order few and sent samples to maukka and djozz.

What is ‘similar’ ? :slight_smile:

Same technologies in led die, phosphor layer and silicon dome = same tint and tint shift problems.
I will have 70cri leds with high bin and low Vf. Datasheet promises output similar to xp-l2 - I dont believe korean datasheets, will be interesting to see real tests.

Before maukka test, what can you say about their tint?

Samsungs are in reel cut, other leds are 4500K XHP50 ( Offer expired ), UV led from convoy s2+.