Project: SUNLIKE LT1 board (Option for 660nm Red)

Put me down for 2 please. Thank You.

2700k + 660 or 630nm ?

yes, I can solder red 2835 leds, but I need to buy it first

I know. Logistically it might be somewhat difficult to coordinate. Sofirn doesn’t seem very flexible especially for small orders from what I’ve seen and read. I’d imagine there would be a lot of hassle trying to coordinate this from the factory.
The best I expect they might be willing to do is sell the LT1 without the MCPCB or LEDs

it is possible to buy it from factory? I need 1pcs to test it. Shipping inside China

This is the cheapest option I believe. It’s a nice lantern and I do recommend them to people. I think we will have enough interest to get this project going but I cannot be certain we will reach 100 pieces of interest at this point.

https://www.aliexpress.com/item/4000238008009.html

50$ :cry:

In for 1.
2700+4000 though I might actually put different warm LEDs so I could go lower, ideally to 1800K or 2000K.

Looks like the outer ring could fit another 4-8 LEDs for a small efficacy / output bump…

I brought up the idea of having 4 more warm emitters than cool ones to LampMan and he said the two colours have similar brightnesses so it would offset the balance.

I’m trying to keep the total cost as far below $20 as possible since the LT1 is only $50 on its own.

We’re talking about 123 vs 153 mA/LED and the same total current. Efficacy improvements will give at most a few percent difference in output. Please note that most of efficacy improvements come from lower Vf rather than higher output. And here this improvement will be burned by 7135s anyway.
And in the datasheet I see a few percent difference between CCTs as well.
So I actually think it would act as an output equalizer.

This may be different if the LT1 driver has extra 7135s soldered (which I would recommend anyway).
EDIT: I see that 7*7135s per channel is the max. So efficiency improvements from having more pads would be quite small but still, they should improve the outputs balance.

This is what I said but LampMan (BelMOR) is adamant that the warm and cool emitters are the same brightness.

I expect the lower Vf than the LH351D and same current but higher light output will result in a cooler LT1 head/top part which is good since that’s where I notice most of the heat building when running my LT1 for extended periods of time with 7 amc7135s active.

Wrong
SunLike LEDs have lower flux per wattage =(
It will not colder or brighter!

Id like to have at least one. Im not too picky and will likely settle on a popular combination of warm tints, once the group reaches a consensus. This is an interesting thread and I appreciate the R&D going into it.

1. I can do 18+18, it is all in this space
2. In future will be 3rd generation of SOL2835, it is much more brighter, but without violet
3. 660nm red have ~2.2v, not ~3v. It will work or no?

I see I’ve made an error. The LH351D has quite a low Vf when only driven at 600mA, about 2.8v while sunlike sol will have a Vf of ~3v at 150mA.

Assume all 7 7135s are active. That’s 2450 mA. Spread between 4 LH351D, that’s ~613mA. Spread between 16 sunlike 2835s is ~153 mA.

The figure I’ve seen thrown around for the LT1 with 7 7135s active is 840 Lumens. With sunlike (using the 64 lumens (5000k) at 150mA figure of the datasheet) the 16 emitters would produce 1024 lumens.

What is the lumens per emitter at 150mA? You say it’s identical for both 2700K and 5000k? This can’t be the case, can it? It seems like warm emitters are always more inefficient since the phosphor layer is thicker?

Correct for optical losses and higher temperature and you’re in the same ballpark but higher colour rendering and rosier.

BTW, I’ve notice a Refond “Sunfeel” mentioned in the catalogue with nicely looking spectrum but I fail to find any details.
https://www.tme.eu/Document/297bac1c849d293b517ecf72110c4a89/catalouge-REFOND.pdf

Does anyone know more about them?

Yeah I’m not so sure about this project. The LT1 emitters are already pretty nice. The uneven glare is a bit annoying though.

When I proposed this I expected the benefits would be:

- Cooler head temperature

- Slightly brighter

- Better colour rendering

  • Smoother beam

It looks like the head temperature might not be cooler and the brightness increase wouldn’t be too substantial.

I’m not sure about the stock tint of the light. It might get a bit rosier? I’ve never thought of my LT1 as being green so it’s not an improvement imo

Wrong

It will be about 600lm, not 1000. I mean with diffuser

BTW, I never use my LT1 above 2700K. I’d like to go warmer.

I’d like to have some cooler spectrum as well because I’d like the candle mode to vary CCT.
But for this to happen without going above 2700K I need some warmer LEDs. So unless I find something warmer it looks like 2700K at both channels would be the best choice for me…

I have a feeling that kapton converters from 7135 to E21A footprint would be a bad idea….but an entertaining one. :wink:

Warmer would be nice but it seems like we don’t have that option unless we find some different LEDs. My guess is that the diffuser should affect the LH351Ds and threes 2835 SOL emitters the same so brightness should be close if not higher with the sunlike emitters.