FW3A, a TLF/BLF EDC flashlight - SST-20 available, coupon codes public

I don’t think TK is using anything like PID, that would be just stupid in a dynamic thing like this that doesn’t work like classroom theory.

It’s not an easy thing to control, and the hardware is fixed, this has to be delivered sooner rather than later, otherwise why even bother ?

Pragmatic solutions are required, whilst we know-it-alls chatter amongst ourselves.

contactcr was nice enough to test the most recent build, the faster-but-still-regulated-during-FET “option A” on an Emisar D4. This was the result:

The level it regulated to may be a bit low, looks like about 300 lm or so, but it was also told to use a pretty low thermal ceiling. And it was probably not being held in a hand, so it wouldn’t have had as much heat sinking as it would during normal use.

Other than that though, I think this result looks pretty good. It adjusted fairly quickly to a stable level, didn’t overshoot, and didn’t bounce around.

Is building a light always like this? Will it ever be built? I had such high hopes too.

People often keep the development process behind closed doors, so it looks like things just pop out of Zeus’s forehead fully formed.

But yeah, development is usually somewhat messy. The difference here is that the process is more transparent. And this project has been particularly slow due to a variety of setbacks.

Ah, if people only knew what it takes to bring a product to market, or to a specific customer. Had to smile of a light popping out of Zeus’s forehead. I can hardly wait to read the discussion about what battery should have been used. . . .

Sorry, didn’t mean to show my age. Old habits die hard.

In for 2


I did some testing on FW3A proto2 running at full power with a fresh 30Q cell, with the thermal ceiling set to 45 C. It was laying sideways on a table with a fan pointed at it. Here was its regulation pattern:

The main difference between options is whether that initial plateau exists. The light gets a bit hot to hold during that.

Although not shown here, beyond the right edge of this graph I put a few drops of water on the light, and it started getting brighter. Then I touched it with ice and it got brighter faster. So… it does step back up when the temperature drops; it’s just not shown on the graph.

The Musical Diversity of Pop Songs
Are Pop Lyrics Getting More Repetitive

Vickers, E., (2010)
The Loudness War: Background, Speculation and Recommendations
AES 129th Convention, San Francisco, CA, USA 2010 Nov 4-7 (Conference Proceedings - non periodical)

Serrà, J., Corral, Á., Boguñá, M., Haro, M., & Arcos, J.L. (2012).
Measuring the Evolution of Contemporary Western Popular Music.
Scientfic Reports, 2, Article 521.

Percino, G., Klimek, P., Thurner, S., (2014)
Instrumental Complexity of Music Genres and Why Simplicity Sells
PLoS ONE 9(12): e115255

Mauch, M., MacCallum R.M., Levy, M., Leroi, A.M. (2015).
The evolution of popular music: USA 1960-2010
Royal Society Open Science, DOI: 10.1098/rsos.150081.

Askin, N., Mauskapf, M. (2017)
What Makes Popular Culture Popular? Product Features and Optimal Differentiation in Music.
American Sociological Review, Vol: 82 issue: 5, page(s): 910-944.

I think the important thing is to remember these studies focus on ‘popular’ music ie what is marketable to the lowest common denominator in order to maximize sales.

I would always squeal with glee whenever another engineer would demolish the cherished subjective world view of the audiophile cognoscenti. Bob Carver remains a hero of mine.

That seems roughly equivalent to what Okcupid found when looking at people who try to make their profile appeal to a general audience instead of showing the things which make them unique. They end up with a lot of 3-star and 4-star ratings but virtually no 5-star ratings.

Whatever the 10% is which counts as “not crud”, I think at least most people can agree that pop music isn’t it. Being too generic makes it bland and mediocre.

As someone who grew up in the singer-songwriter era, it is especially shocking to me that the majority of popular songs over the past decade + have essentially come from two writers; Max Martin & Lukasz Gottwald (Dr Luke). There have always been prolific writers who sold songs to other artists, but I don’t think there has ever been an era when virtually all the top acts are little more than pretty facades.

Sigh…I’m going to go listen to some Alabama Shakes now to remind myself there are still amazing & unique talents out there.

Wow, I’m late on this one. I guess I have a lot of reading to do to catch up, but in the meantime, I’m in for one! This project sounds pretty hot, lol. :person_facepalming: :heart_eyes:

I sometimes put a light in a cool glass of water, where the cooling is usually sufficient to enable quite a lot higher output. I want the 1100>turbo range to have some sort of regulation in it, so that I can place the light in the water when it’s been running at the thermal limit and have it step up to the new equilibrium.

I’ll throw my voice in as someone who has a D4 and wants option A. I think the times I would use FET instead of the 7135 mode would be A) When I only want to use turbo for as long as possible before regulating down to whatever I can get and B) When I have enough cooling whether because it’s cold or wet enough to sustain more heat than the 7135 mode produces. Or if for whatever other reason it had more cooling than otherwise, or if I was less bothered by the heat or something.

This is the conundrum, fitting 3/4 of a Q8 into an S2 sized package.

“Ye cannae change the laws of physics”.

“I’ve got to have 30 minutes” …

Perhaps filling the head with a phase change material could keep it going on turbo for more than a minute before step down. Much much better than simply relying on thermal mass.

Quick estimate: Paraffin wax, heat of fusion 250 kJ/kg.

Find a way to fit say 25g, that could soak up 6.25 kJ, lets say on turbo its pulling 4A from 3.7V = 14.8 W ignoring the light coming out of the front.

So the wax could maintain the head at a safe level for 422 seconds = 7 minutes of full turbo before step down became necessary. Of course there would then have to be a lengthy cooling off period before giving it another full blast. Meanwhile it would make a nice handwarmer on cold days.

Another wacky idea: monitor the LED forward voltage shift with temperature to get a precise reading of the LED junction temperature rise. Saves the need for an MCPCB sensor and measures it where it really matters. Use high melting point solder too, in case of accidents.

PS: if there are going to be FW3Ti and FW3Cu in future, the thermal control may need some re-tuning to cope with the very different thermal properties in case A (particularly for Ti), hopefully the “universal” system will adapt when in 7135 mode.

PPS: I think there is still a place for “hotwires” in bright torches, at least the incandescent bulb chucks it’s waste heat out of the front instead of into an MCPCB, and of course the CRI is perfect :wink: Make a handy fire-starter in emergencies too.

Another vote for option B - safest option!


First off - thank you!

I’ll say I haven’t followed every minute of this behemoth thread, so pardon if this has already been discussed extensively…

My first thought is if we want the PID to function perfectly and be the sole method (over months and years of operation and thousands of samples!) keeping this thing from going to skin blistering temperatures is to have a dedicated thermal sensor as close to the (primary) heat source as possible. It’s very common practice now for bigger name manufacturers to have an NTC thermistor on the MCPCB. Measuring this far upstream will make it possible to get AHEAD of the temp control, and not require so much host calibration or predictive/preemptive throttling. One major concern I have with using the current temp sensor location, besides the obvious and previously stated shortcomings, is the driver retaining ring possibly coming loose on the F3WA. Most of you with a convoy tube light with right-hand-threaded tailswitch retaining rings has come across it loose over repeated use and battery changes. This could cause a serious change in thermal resistance in the sense circuit and potentially lead to extreme over temperature conditions. Small chance maybe, but one that’s avoidable IMO.

That said, if this can’t be done at this point in the project, then I really hope the safest and most reliable options are employed to limit the >1000 lumen modes. If timed step-down from turbo to high is necessary, that’s fine! Everyday carry is exactly what a light like this exists for, and no reasonable person would prefer burnt clothing and/or skin over an extra click to keep it in turbo if necessary.

Just for perspective, I remember the Eagle Eye X6 group buy, when we were hoping the light would be able to ACHIEVE 1000 lumens.

A MCPCB-mounted sensor would be awesome, but won’t be feasible on this light. Maybe in a later version, with a redesigned driver.

So for now the MCU is stuck making predictions based on a laggy and noisy built-in sensor.

Despite that though, the normal regulation works pretty well… except for the specific case of turbo, which it allows to run long enough to make the light uncomfortable to hold. But perhaps that could be avoided by adding a drop of thermal goo in production. That just makes the driver really hard to reflash. I hope future drivers will have programming pin access on the battery side of the driver, though the FW3A may not have room for that kind of thing.

The retaining ring doesn’t actually touch the body tube, so it’s far less likely to get loose over time. In the prototypes it does sometimes touch the inner tube though, which is a main factor holding up the project. Can’t go to production until that’s solved, because spurious button presses are bad. It’s easily fixed with a short strip of kapton tape around the end of the inner tube, but a better solution is needed.

Given how hot most of the electronics can run safely versus the low temperatures we’re expecting of them, and the fact that burns to clothing and such from lights like the d4 and this come from the intense light and not the body of the light itself, I don’t think that the non-muggle mode should be quite so cautious that being even a degree over the setpoint for a few moments would prompt a stepdown. I think it should just be allowed to get a bit uncomfortable for a few moments to allow you to see whatever it was you activated turbo to see, then let the thermal control figure itself out and lower it down into the sweetspot of the regulation range. And of course the potential of operating it in a cold or wet environment where the full turbo heat would be easily dissipated is a big point - if I used this as a handwarmer or in water to keep it cool.