*BLF LT1 Lantern Project) (updated Nov,17,2020)

I got the Q8 numbers from a post by CivilGearReviews, which cited alleged mfr test runtime results. Note the “Group 8” data line in the chart.
CivilGearReviews thread
Not saying that I’ve done anything to confirm accuracy of those numbers, though.
I’m not comparing max output to max output, but rather m/l equivalent lumens of output.

Runtime of the LT1 at high setting has been mentioned by several people, and GreenCampfire did a runtime test and posted a graph showing almost 6 hours before output fell off sharply.

Maybe I missed it, but does anyone know what the button LED turning on halfway through the ramp signifies? Usually it’s the FET channel turning on in other lights, but the LT1 doesn’t have a FET.

It’s just an arbitrary value (65/150). It also doesn’t turn on, it switches to high (and is very dim before that).

I’d love to see an LT1 pro with a boost driver (buck has flickering issue) and a better thermal path which directs more heat to the body.

Not sure what you mean. A buck regulator does not flicker.

Lately, I have been discussing some ideas with Barry (Sofirn) and DBSAR, among them a (limited) run of a special LT1R with Samsung LH351D 4000K 90CRI and Luminus SST20-DR 660nm.

Basically, we would sacrifice standard tint ramping between 5000K and 2700K (LT1) and exchange that by tint ramping between a warm neutralwhite 4000K HighCRI and a true deep red tint with 660nm wavelength. Additionally, this LT1R could be anodized in red color (not discussed with Sofirn yet) to emphasize the unique proposition of this model. This plan would mean very little efforts in (re-)development if any and keep markup costs to a minimum.

Certainly, most of us would prefer to have a three-channel LT1 with both 5000K, 2700K and deep red light. But that would imply:

  • significant changes on the LT1 source code (incorporate third channel tint ramp, underneath the "bottom" of warmwhite floor level)
  • that ToyKeeper (or someone else's expertise) was required to revise that source code accordingly
  • that Sofirn had to revise their current LT1 driver design and add a third channel, place additional 7135s on the driver board
  • that we talk about a whole different timeline, probably not feasible within the next 6 months
  • that hardware costs could be added at unforeseeable level due to the global semiconductor shortages right now

Maybe I am going to run a poll anytime soon. But before that I am curious about some general opinions, especially upon tint ramping between white and (deep) red light.

**significant changes on the LT1 source code (incorporate third channel tint ramp, underneath the “bottom” of warmwhite floor level)
that ToyKeeper (or someone else’s expertise) was required to revise that source code accordingly

I’m not sure exactly how significant this is but it seems like it should be possible to someone knowledgeable without being too. You could probably create a tint ramp2 (or reuse the current tint ramp) which gets accessed with a different click sequence when already at the bottom of the tint ramp. I’m not super knowledgeable about the code but I think it could be done, even without TK’s help

that Sofirn had to revise their current LT1 driver design and add a third channel, place additional 7135s on the driver board
This has already been done. Sofirn has a revised board with a third channel of 7135s labelled red

that we talk about a whole different timeline, probably not feasible within the next 6 months
Not an issue to me. These are more longer term plans

that hardware costs could be added at unforeseeable level due to the global semiconductor shortages right now

What are they having trouble getting? The components of the red LT1 board seem identical to the current board with the addition of a few 7135s

For me, a red channel is a bit of a gimmick and I really wouldn’t like to see it come at the cost of regular tint ramping. That seems like an avoidable and undesirable compromise.

In an effort to not deviate from the current conversation, here’s a link to a new thread I’ve opened regarding the idea of swapping a board of Sunlike ~98cri emitters into the LT1 for better colour rendering and less heat at the head.

The cost if we get 100 people interested would be about $12 a board + $4 shipping which you’d swap it into the lantern yourself.


May be someone have correct sizes of this pcb? +/- .5mm

I’m on board with a LT1R, I think a red channel would be a perfect addition. However, if we are limited to one CCT I would suggest going with 2700k, or at least warmer than 4000k.

It seems from a lot of replies on the forum that most folks prefer the warmer tints out of the lantern. Even following the Sunlike board discussions, there are folks that have requested an even warmer tint that 2700k.

I second this!

I will check with Sofirn if their suppliers can offer LH351B 2200K 80CRI (SPHWH2L3D30ED4Y). Maybe this could be an interesting option for a 2-channel LT1R with 2200K and SST20-DR 660nm.

I have a modified SP10B with LH351B 2200K 80CRI and the tint looks gorgeous. I hope its characteristics will not be too far off to implement into the current driver layout. Overall maximum brightness will certainly decrease using LH351B and SST20-DR.

For those who already own an LT1 and want red light without buying a new LT1 :

LampMan will be offering the Sunlike LT1 Board with 660nm emitters and you can to pick the CCT of the emitters in the other channel. CCTs available will be 2700k-5600K.

How much efforts would it mean to replace the LED board by the Sunlike LT1 board?

I haven’t yet disassembled my LT1 but from what I understand, the process is pretty straightforwards.
No special ring pliers, just need a hex key, a philips screwdriver, a soldering iron, and some thermal paste

1. Use a Hex key to unscrew the top then take the top apart.
2. Desolder and remove original MCPCB, clean the thermal paste. (Need a screw driver too)
3. add new thermal paste and solder in the new MCPCB
4. Test your connections then reassemble the light.


Lex, Id be in for a LT1R if the host was bright red anodized. I have no use for something so yellow and dingy as 2200K 80 CRI, but would love the suggested 4000K 90 CRI. Fingers crosses for a red anodized version, otherwise I probably wouldn’t be interested.

Maybe another option would be to ask Sofirn if populated MCPCB’s could be sold in a variety of tints. The swap sure looks easy enough for anyone who can solder.

While I think the Sunlike project will be a fun mod to experiment with, I dont see the 2835 Chinese emitters replacing the robust Samsung LH351D emitters and DTP MCPCB of the stock LT1 over the long haul. If the 2835 SMD’s were Cree or Bridgelux, Id have a lot more confidence in them meeting certified lumen maintenance specs… which means they would meet published longevity standards if ran at spec, rather than the cheep Chinese LED light strip emitters being used, which are subject to burn out far more quickly. Ive sure gone through my share! Just my .02 cents…

Any news on the 8 x 18650 mod kit for the LT1?

The leds for the Sunlike boards are Sunlike, which is a cooperation between Seoul Semiconductors and Toshiba. So no chinese leds. And even if they were chinese (btw, even chinese leds are improving all the time :wink: ) there is no reason to expect them not no last many thousands of hours, if things go wrong with cheap led products, it is always the electronics, not the leds.

I disagree with your comments regarding the robustness of the Sunlike board. The emitters are made by Seoul Semiconductor which is a reputable company and not some noname Chinese manufacturer.

I have faith in BelMOR’s judgments because he is experienced in this field and has been selling his bulbs for some time.

I don’t believe a DTP board is needed. Each emitter is getting at most 153mA at 3V, that’s less than half a watt of power.
DTP is necessary when you’re driving high power emitter beyond specs. 150mA is the average rated spec of these Sunlike emitters with their max current being 300mA

7 AMC7135s active results in just 2.45A, being shared between 16 emitters is not a lot of heat to dissipate.

I wouldn’t move ahead with this project if I didn’t think the final result would be a good, robust design.

Thank you, and I stand corrected. So getting into it… browsing SOL’s 2835 data sheets were rather spartan and lacking, which did not inspire confidence. Nor could I find any of their emitters being used by large certified luminary manufacturers. Also, CRI was rated >80, not the high 90’s. I was also put off by the response I received from SunLike when I asked him about the higher binned 2835’s he had mentioned. He also ditched Sunnysunsun when he asked for a datasheet. Perhaps a language barrier, or just a sales driven ambitious fellow anxious to make a buck. Reading his older threads… I felt the same hard push to sell and avoidance to anything that might prevent that from happening. After further searching, I couldn’t find any independent reviews concerning the longevity of any of his products. Now having said all that, I was still interested in one of his boards… its only $20, but Id rather have the stated much brighter emitters he had mentioned that were in the works. I’ll see when those might become available through SSC/SOL, if I haven’t lost interest by the time he’s producing the boards. I often browse industry publications and business related articles because I sell large high value luminaries to local businesses (typically GE and RAB products), thus my interest. I have yet to ever see or read about one implementing SSC/SOL emitters. Probably because they do not appear to carry industry certification standards, which eliminates them from certified commercial markets and vendor lists. All comments welcome. Its another toy to play with, and I think the research is half the fun for most of us. Im probably done digging for now.

Im still much more interested in owning a nice red anodized LT1R. Hopefully it will happen soon.

Cheers! :beer:

SunLike products are not sold everywhere, just as you will not easily find Optisolis products. The reason I think is not so much the quality, but that the lighting industry is (still?) very much focused on 80CRI, 90CRI the most. 95+CRI products is a niche market. There is a rather large german company, Lumitronix, that has SunLike products in their standard assortment: https://www.leds.de/catalogsearch/result/?q=Sunlike

About the guy from Belarus, I think that he is doing interesting stuff on the boundary of DIY and professional work, that is too specialistic for most companies to be profitable. He has his typical way of communicating things, that may be a personal or a cultural thing, but I also think that he is starting up his company, is not rich and really needs the money, and is blunt about that.