Best high CRI for GT-mini ?

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FabienG
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Best high CRI for GT-mini ?

Hello Smile I am looking for GT-mini users advises :::

What is the brightest CRI90+ led usable in that flashlight? Can I use a SST-20 on 20mm MCPCB in that flashlight or should I order a 16mm?

Thanks!

Agro
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It depends on what you mean by “bright”.
Do you want a narrow beam thrower that reaches very far or a wide beam flooder that gives a lot of light at short distance?

FabienG
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I am not sure which led would give the best result. If not mistaken, a 219C is more floody than the tiny sst-20, but many people complain about the greenish tint of the sst-20. GT-mini is purely a thrower, I rather go for the sst.

Agro? Do you know what is the diameter of the mcpcb inside the gt-mini? Is it possible to just unscrew the bezel and directly swap it with a noctigon as above?

Agro
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I think I know the diameter but I’d rather not give you uncertain information. I’ll leave that to others.
The LED swap procedure is described nicely here. It’s for another light and it includes driver swap. But when it comes to the LED, the task is the same in Convoy C8 and GT Mini. Unscrew, unsolder, replace, resolder, screw back. And do several other steps as well.

When it comes to the LED, SST-20 seems like a fair suggestion for you. If you want to avoid greenness, buy the LED here, this is much better.

Also, a powerful 18650 cell with overdrive SST-20 with a powerful driver (like the GT Mini one). To run it safely you need to do one of the following:

  • never use the light with a powerful 18650 cell
    • 10A 18650 should be OK
    • 18350 should be OK
  • change firmware so it never runs the LED at 100%
  • replace the driver with a regulated one
    • would be the best option but there is no obvious choice, sadly
  • add enough resistance to keep peak current low
    • thin lead wires?
    • high resistance springs?

So…this is not as easy. I have another suggestion though:
If colour temperature of 3000K is OK for you, use Cree XP-L HI instead. It will throw about as far (maybe marginally less) and be significantly more efficient. Stock driver will work great with it.

djozz
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The SST-20 is the throwiest high CRI led atm, and a very nice one too. If you are brave you can even slice a 4000K SST-20 to just above the bond wires, it reduces output by 20% but still increases throw and improve tint because it lowers the duv: you end up at about 3600K. If you start slicing leds be sure you have a few spares around Wink

Agro
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I don’t think SST-20 is the throwiest.

I believe that:

  • XHP35 HI outthrows it
  • XP-L HI outthrows it (but needs a high voltage driver to do so)
  • Luxeon Z ES is about as good, probably slightly better
  • Luxeon CZ is likely to be the throwiest around

But it’s known to be good and reasonably easy to put in GT Mini.

FabienG
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I never tried to slice any led before… Too micro-acrobatic for me Big Smile

Regarding the link for the sst purchase, the list is already closed.

I am just curious about that tint vs cri debate, if 2 leds have the exact same cri index, does it really matter if one looks greenier or rosier than the other one?

BlueSwordM
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@Agro, in the 70CRI variant, the SST-20 will throw farther than the XP-L HI since efficiency is similar, and has a smaller die optically, and the XHP35HI, even more so

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

Agro
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CRI70 XP-L HI was measured to deliver 168 cd/mm² and XHP35 HI – 172 cd/mm² (source).
I’m yet to see anyone measuring luminosity of SST-20, but based on comparative results I estimate CRI95 SST-20 to max out around 100 cd/mm², maybe a little less maybe a little more and CRI70 one surely above 100 cd/mm². But nowhere near 170.
That’s with a dome. Dedoming helps but from memory it’s 0-20% in the case of SST-20. Literally, I think some users didn’t gain any throw. I calculate the top CRI90 bin of XHP35 HI to deliver near 130 cd/mm².
So…I believe Cree chips would win this match when driven properly.

BlueSwordM
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How come then does it throw farther at the same lumen count like in the Emisar D4/D4S?

https://intl-outdoor.com/emisar-d4s-26650-high-power-led-flashlight-p-93...

And it’s got a similar VF vs the XP-L HI.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

HONDARIDER
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The SST-20 will out perform either XP-L HI or the XHP35 HI in the GT Mini due to the die size. You may get more lumens out of the other 2 but beam size will be much narrower with the SST giving it greater throw.

Barkuti
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It is a bit of a shame you still have to deal with @#$% unregulated drivers just because you are addicted to certain “ATtiny only” software for them. It's like using Commodore Amigas, yes they were great… 25 - 30 years ago maybe. I do not mean to be over critical, it is just that a regulated driver is not that difficult to implement. Look at all the new offerings in the Convoy store, for example. The software, though, needs to be migrated. If you really can't do without such software, maybe you should set a goal, gather money and pay someone for the code to migrate.

It certainly is better to use a beefy MOSFET in linear mode than crappy 7135 chips which don't even PWM well at high frequency. Just a suggestion. 

 

Smile 

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Quote:
Just a suggestion

Suggestions into the blue sky will not get anywhere, that is why you have been preaching this for over a year and nothing is done with it. I suggest you team up with a driver electronics expert and make this wonderful driver a reality.
FabienG
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Let’s forget about “which led is the brightest”. It seems that nobody agrees on that.

I will try and see which one looks better for my application.

Then, what about the MCPCB diameter ? Can I use a Noctigon 20mm ?

Barkuti wrote:


It certainly is better to use a beefy MOSFET in linear mode than crappy 7135 chips which don’t even PWM well at high frequency. Just a suggestion. 


 


Smile 

I just ordered a GT-mini, is the driver not good? Is it going to flicker?? Flat Stare

Barkuti
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It is you who will get nowhere with such attitude djozz. I understand nothing will get done, because for you that is no problem or deep within you believe you can't do @#$%. You could, it just is you aren't ready.

Have fun.

 

Smile

djozz
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Nope, driver electronics is not my expertise and my expectation is that it never will be, the optics side of flashlights is just too interesting to focus on something else (I would have a loong way to go).
Maybe that is why I’m so glad with what drivers have been made available by others. I know they are not perfect but I think they do a fine job and I happily use them. Smile

oweban
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Yep, it’s a 20mm MCPCB. Swapped one out the other day.

Somewhat related – anyone know where to source a spare driver board for the GT Mini? Smile

djozz
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Request Neal, he got me a few too (I blew a driver, so I asked and received them, it was the 7135 that blew so I could repair the stock driver too)

If he can’t get you one I’m happy to send one across the earth no problem Smile

oweban
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Haha, nice, thanks. Killed mine white doing a white flat swap somehow; I’ve removed all the components from the board and the r5 resistor was cracked in half, but that shouldn’t have caused the issue I had (instant power to emitters with tube connection). So I started sanding it down to make sure it was definitely clean under and look at the circuit flow:

http://imgur.com/a/im5qPUB

Cheers! Didn’t even think to contact Neal.

Bob_McBob
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If we’re talking about high CRI options here, the 3500K GA3 SST-20s I’ve used don’t throw as far as the stock 4000K CRI 70 XP-L HI in my GT mini. It was about 600m vs. 685m. A straight slice at the bond wire height reduced output so much it negated any extra throw, though it does significantly improve tint. Carefully trimming around the die and wires gets me about the same throw as the XP-L HI, though a considerably narrower beam. I plan to change out the dedomed 3500K for a 4000K at some point soon.

ToyKeeper
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djozz wrote:
make this wonderful driver a reality

Indeed. Thumbs Up

Be the change you want to see in the world. Instead of tearing down what you don’t like, build something better.

In more blunt terms, put up or shut up. That’s how things work around here. No amount of “thinking higher” or “believing right” will change reality… that’s just a drug, a way to create a pleasant illusion with no substance. To make concrete things happen, you have to get your head out of the clouds, get your butt off the chair, and put one foot in front of the other until you are where you want to be. The power of the mind may help with choosing a destination, but only the power of the feet will get you there.
Barkuti
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This “SST-40 8A” driver uses an ATtiny something, by the way. I doesn't works like the usual ones, but it's a start I'd say. Smile

 

FabienG
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oweban wrote:
Yep, it’s a 20mm MCPCB. Swapped one out the other day.

Somewhat related – anyone know where to source a spare driver board for the GT Mini? Smile

Thanks! I’ll order different led on 20mm, and check which one looks better in that thrower. I’ll try those:

sst-20 4000k 95cri
sst-20 3500k 95cri
219C 5000k 90cri

last one should be more floody, but clean white…

Is there anybody having extra SST-20s FD2 95CRI in stock ?

https://www.reddit.com/r/flashlight/comments/bv9jlm/sst20_4000k_fd2_unde...

Agro
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BlueSwordM wrote:
How come then does it throw farther at the same lumen count like in the Emisar D4/D4S?

https://intl-outdoor.com/emisar-d4s-26650-high-power-led-flashlight-p-93...

And it’s got a similar VF vs the XP-L HI.


A few weeks ago I compiled SST-20 numbers from as many sources as I could find. They varied wildly and the Emisar numbers that you show were way higher than average (but there was one other measurement with similar result).
Boaz
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ToyKeeper wrote:
djozz wrote:
make this wonderful driver a reality
Indeed. Thumbs Up Be the change you want to see in the world. Instead of tearing down what you don't like, build something better.
In more blunt terms, put up or shut up. That's how things work around here. No amount of "thinking higher" or "believing right" will change reality... that's just a drug, a way to create a pleasant illusion with no substance. To make concrete things happen, you have to get your head out of the clouds, get your butt off the chair, and put one foot in front of the other until you are where you want to be. The power of the mind may help with choosing a destination, but only the power of the feet will get you there.

 

We are the world ...we are the children ... 

 

       καὶ τὸ φῶς ἐν τῇ σκοτίᾳ φαίνει καὶ ἡ σκοτία αὐτὸ οὐ κατέλαβεν

                                  https://www.gty.org/

 

    Still selling diffuser film  >…  http://budgetlightforum.com/node/42208

FabienG
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Michael Smile

FabienG
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No more FD2 Facepalm only FB4 left…

FabienG
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I have to purchase some 20mm MCPCB and find a way to reflow those leds. I hope not to kill them lol

FabienG
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Yes ! Ready for reflowing Big Smile

FabienG
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It arrived today,

BUT hell, how you guys managed to unscrew the bezel? Is it really glued with blue loctite??

oweban
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Mine was really tight too – just took me a while to get a good grip on it and give it hell. No loctite that I could notice in the threads, and it’s been easy ever since to open/close.

/shrug

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