Hmmmmm. Iām not sure why my clip came unbranded and yours didnāt.
The other thing I thought was strange is my clip showed up to my New Hampshire USA residence 5 to 7 days after ordered. Fastest boat from China ever.
TK, will you also be doing reviews on the other upcoming Emisar lights?
TK, I have a question for you too. Is there intention to put your latest developments on the future Emisar lights? I mean both UI rewrite and thermal improvements.
Iāll probably review the D1 at least, whenever thatās available. Iām somewhat less interested in the D1S and D7 though, because theyāre bigger and more specialized. Of course, that said, the D1S seems like a pretty good replacement for a C8 or X6 so itāll probably be pretty popular too. And soda can lights are fun, even if theyāre a bit much for my purposes.
I donāt know any details yet about future Emisar firmware. It depends on what Hank wants.
The new code is getting pretty close, at least. I did some thermal testing and tweaking today, and hereās how the result looked on the hottest most over-powered light I have: (D4 219c running at full power, ~20 amps initially)
The initial little dip at the top was me moving the light, but after that I held it pretty steady. There were also a couple times later I moved to switch hands, but I tried to keep the light from moving.
What this graph shows is that the adjustments are smooth and gradual now (hard to see without tools), that it reaches its stable state fairly quickly without wrong turns, and that it stays reasonably stable afterward. I had the temperature limit set fairly low to try to make it overshoot or bounce, but it behaved pretty well anyway.
What the graph doesnāt show is that the D4 219c still gets painfully hot during the first minute, even while constantly reducing power. I has way too much power for its thermal mass. So, on mine when Iām not testing stuff I set the default ramp ceiling to about half power, and the heat becomes much more manageable.
Also not shown: it reacts much faster to changing environmental conditions now. Get it wet or touch it with something cold, and itāll raise the output pretty quickly.
Ooo, that is nice.
Your work rate is scary, by the way 
Out of curiosity, I tested thermal regulation on a light with a H17F driver, a brand new Okluma copper DC2. Jeff sent me one to thank me for all the free code, and perhaps also because I think he might want an open-source version of it. And I graphed it against my D4-219c:
The H17F thermal ramp-down is as smooth as it can get (the occasional bump was because I was holding the light and I moved). It seems to step down at a maximum speed of two PWM levels per second on FET modes or one PWM level per second otherwise, one channel at a time, until the temperature is no longer out of spec. This makes it really smooth but also really slow. Eight minutes to reach stable state at the configured temperature limit.
My FSM-based D4 also steps down one PWM level at a time, but itās much faster, up to 8 adjustments per second. It looks just as smooth in person, but it reaches its destination(s) sooner and then is a bit more jittery after reaching stable state. One minute to reach stable state in this test, and another minute for the aluminum bodyās outer temperature to catch up.
The DC2ās slow response seemed appropriate though, because it has a massive chunk of copper to sink heat into. It never got too hot to hold; the outside of the light stayed a pretty steady temperature.
Meanwhile, the higher-powered D4 has only a small chunk of aluminum, so it got painfully hot during the first minute even though it was stepping down so fast. It remained pretty hot during the second minute, but it did not continue to ramp down because the predictive algorithm figured out that there was no need since the temperature was already decreasing fast enough.
As a side note, I need to recharge the DC2ās battery and measure its maximum output properly. Its vertical scale on this graph may be a bit off ā IIRC it was about 2300 or 2400 lm at the beginning but I need to double check.
Itād be interesting to see how each light behaves with the drivers swapped. Thatās not very feasible, but sometime soon I should at least be able to measure FSMās behavior on a larger light, a SRK or Q8. If my guesses are right, it should still work fine with more thermal mass and should adjust output more slowly, because the extra thermal mass reduces the rate of change and that reduces the magnitude of response.
(edit: it occurs to me this isnāt really about the D4; I should put this in the FSM thread instead)
This would be a nice add-on for the Emisar D4 
Ah, heck. I just bought one.
Kind of been waiting for the D1 of which i will probably get(have limited use for throw bias lights)ā¦ā¦ā¦ā¦ā¦be rude not to i guess! So another D4 in xp-g2 4000k flavour on the way. Really like 4000k for that little hint of warmth in the beam. makes my tired eyes happy
They are like Maine Coons, you canāt have just one
Nice to read youāve become a believer. :partying_face: 
Easily the most addictive light I own, I actually enjoy the heat when itās cold out.
Ordered, green 3A
Damn, i looked literally 5 mins before my post and ordered another D4, so needless to say a D1 is ordered as well, 5000k flavour of course
Which color?
I have the same on pre-order at Mountain Electronics. Wish a 4000k XP-L was an option. I have a few triples with the 4000k XP-L and they are a great tint!
If me, boring black ā¦ā¦ā¦ā¦ā¦.almost went greenā¦ā¦ā¦ā¦.almost , so maybe the next(did i say next) 
Thinking of black this time, but Iām still undecided. Iāve already got one green and one grey D4.
Thats easy then, boring black 