It would be an even more special project if the CCT changed continuously with ramping the brightness (sort of following the Kruithof curve) . It would require leds of two colour temperatures (say 2700K and 4500K) well blended in the beam, controlled by two separate pins of the MCU.
And a fair bit of programming and tuning a new ramping table.
That would make a good option indeed for those who like to change the color tint for different used, but as you said would require more components and drive the price up for the lantern.
Here are 80CRI 3500K LEDs too if you want something warmer. They would also be even higher output than the 4000K 90CRI though I realize that isn’t needed in this lantern.
No offense intended, but didn’t we kinda chat about this yesterday? Digikey carries 8 varieties of the LH351D that are available by the piece, but they don’t have any stock of the 90 CRI - those appear to be special order. It would be nice if they stocked those as well, though.
Either way… I personally feel that 80 CRI would be good enough for campground usage, but I’m definitely not a CRI snob and I don’t mean to spoil anyone’s fun that has an appetite for 90+ CRI.
That’s probably pretty do-able. It could use 1x7135 for a warm tint and 3x7135 for a cool tint, or maybe 2 and 2, or 2 and 3, or something like that. If it’s intended to always be warm when low and cool when high, it wouldn’t even require any code changes — just a new ramp table.
Or it could do manual color temperature changes — a single ramp which splits into both emitter types based on a user-adjustable balance.
Or it might be possible to fit both.
If the hardware has two individually-controllable tints, I can find a way to make it work. The main questions are whether the idea is worth doing, and how exactly it should work.
Creating the firmware and designing the board circuit is out of my capability range, but Toykeeper i believe can chime in on that idea. In this case a similar LED star as the Q8, but with pads for eight LEDs, with dual input paths for four each of 3000K & 4000K. (maybe we can get some of the other Q8 developers in on this project too. hints
Is the lantern originally designed for two LEDs? If so, a two-color design should be feasible with four total emitters. Or if there’s too much angular shift with two of each, maybe it could do three of each? I doubt four of each would be needed, especially at the low levels the lantern is running at.
If it has two tints, I’d suggest doing ~3000K and ~5000K, or if they’re available, perhaps even warmer than 3000K.
If user-adjustable color is desired it may also be worth increasing the total number of 7135 chips, so it can reach the original brightness target at any tint. That will move the levels a bit farther apart at the low end, so the bottom end of the ramp won’t be as smooth, but it’ll probably be fine.
Since i am using the Q8 star in the V2 prototype, it now has four LEDs. Right now I plan to increase the number of the main 7135s to four (for 1.4 amps max) next week after the first field testing with the three , ( + the original one already on the driver for the low modes.