I still do not see why a simple FET+1 driver would not drive the CFT90.
About the design: you emphasized heavily on the finning (I like that) but still what you have drawn I estimate can dissipate about 25W, not the 100W that you want the CFT90 ideally to run at. But since people do want that 100W (or whatever the 21700 will provide) for a while before the stepdown, you can buy some time with extra aluminium mass near the led, also good for distribution of heat to the fins. So I would suggest a bit less deep fins and a bit more aluminium.
I would love to know how do you estimate the performance of these fins?
Frankly, I think it would be good to make the reflector like 4 mm larger. Right now it’s quite small when considering the total size of the light. It was just easier to draw it like that because it’s just a modification of one unpublished drawing……
Making reflector larger would improve heat shedding. Though certainly not quadruple it. My intention with this light was to have fins remove at least 70% of heat. If that was the case, already quite large chunk of metal behind the LED should allow for a nice Turbo times - and superb sustained performance would be a nice bonus.
It would be wrong to treat those fins literally. I think if such light was to be done, someone should just design a light with lots of fins in this area, adjusting exact fin spacing and thickness to whatever thermal CAD shows to be best within structural limits.
But I was curious whether your 4x was about right, so I did just that: treated those fins literally and calculated area.
I got 5 times the area. So about right. Though in your S2+ analysis I see the light being run at 10W+, not about 6 like your calculation would show.
It seems to me that this light can shed very very roughly 50W with 90 C body temp (I don’t see ambient temp in your tests…can I assume 20C?). Or very very roughly 25W with more sensible 60C. In the winter, with –10C ambient very very roughly 50W again.
Though it doesn’t include cooling with hands, it adds some.
Minor increase of fin area by making reflector larger can help, but not enough.
One thing you have to watch for with heatsinking fins is that deep, narrow cuts between fins can result in stagnant, hot air at the bottom of each cut that doesn’t circulate because it’s buffered away from the cool air outside by the warm air in between.
This means that you can’t assume heat dissipation will scale purely with the surface area. The arrangement of that surface area in terms of getting as much free air circulation as possible also matters.
There is often an optimal point in width, depth and separation of fins, sitting somewhere on a spectrum of:
no fins and poor heat dissipation;
through several fins with optimal width, depth and separation for free air circulation and good heat dissipation;
to lots of thin, tightly spaced, deeply cut fins with stagnant air zones at the bottom of the cuts and mediocre heat dissipation.
The last option is better than no fins at all, but not as good as the optimal arrangement. In the absence of (expensive and complex) modelling software, it’s not unusual for manufacturers to build several prototypes with different fin arrangements and physically measure which does best.
OK, I hate to not have drawings. I still consider the questions above to be open, but I drew pretty much the smallest variant:
10 mm TIR optics, twisty with QTC pill and bypass to real direct drive (thanks CRX), tiny charging connector.
Pictured next to DQG Tiny AAA.
Adding features will make it larger than Tiny. So will increasing TIR size.
Though Tiny has 15-20 times lower output, so maybe that’s not the best light to compare to…
Is it worthwhile? I don’t know. But I’m partial to QTC twisties.
I believe that at some point adding more aluminium is just wrong, it adds too much weight.
If you heat 1g of aluminum from 20C to 60C, it can store ~36 Ws of heat.
If you heat 1g of paraffin wax from 20C to 60C, it can store ~310 Ws of heat.
That’s why some time ago I suggested this: http://budgetlightforum.com/comment/1310922
ADDED:
Paraffin wax is 3 times lighter than aluminium, so volumetric heat capacity is just 3 times better.
For sustained performance, transfer is everything, storage is nothing.
For turbo times both matter. In highly overpowered lights (and this one is highly overpowered even with all those fins), storage is far more important of the two.
I have a few manufactures wanting to do a BLF light along with several ideas of my own but I don’t want to do it like the GT again, that was WAY WAY too much manual labor.
So I am looking for options to vastly reduce the manual labor involved in the process and one possibility is to get an outside site with a shopping cart setup to handle a big part of the labor involved with a GB. This would cost something, although no idea how much.
If anyone has any experience or knows of an option to maintaining an interest list and the purchasing of the item in a more automated fashion, please let me know.
If there is some money left in the BLF donation fund I think that setting up a method to make future GB’s much simpler and smoother would be a worthwhile investment personally.
It seems fairly common for flashlight vendors to come to BLF expecting it to be, basically, a way to market their products… an easy way to make a profit. Generally when companies take that approach, I turn them down because they’re missing the point — although tuángòu happens here, that’s not the purpose of the forum. And if it’s vendor-initiated, I’m not sure that’s really the point of tuángòu either.
However, when a vendor wants to participate in the community in a meaningful way, chatting and collaborating and giving something back, I try to help them.
The commercialization of BLF is a controversial topic, a mixed bag, but I hope we can guide it in directions which are a win for everyone instead of just making the site an advertising platform. I don’t think we need another Massdrop, Woot, or Groupon.
I agree, I have turned down several manufactures that were obviously in it just for the money already.
The only ones I even consider working with are ones that take feedback and work with us for the greater good.
In this particular case most of the projects and manufactures I am talking to now are wanting to make the next BLF design, they just have different opinions on the basic form factor they would like to make (which makes sense, they want it to fit into their existing lineup).
I guess I should of said I have several production facilities ready and willing to help us bring the next BLF project to market.
Thank you, I thought it was too… as well as an important one.
Hopefully the person that has the money will either update the thread if the balance left is not up to date OR turn over the $486.37 so it can be used to do some good.
You want fun with computers.
Try my decade 77yrs.
We started with pen and paper. Slide rules. Then calculators.
Then came games. then came 286 WOW. updated to 386 with a 5 meg HDD. and 5in floppy’s. super wow.
Thennnnn. Mr WINDOWS popped up. with a “mouse”. Quick. hide it from the cat.
No more keyboard and DOSS for everything. Just programming nowadays. Heaven.
Then Win 3 etc. The rest is history.
Linux for experimenters and Apple for. Who knows what??.
I don’t. it has nothing that turns me on.
YOU lot have it sooo easy. you could never envisage…
Plus internet that actually moves.
and is NOT connected to a ph line that’s “programmed” to drop out every ten minutes
to make them more money with your constant redialling. Yep that was real good.
Win 7 was good, finally. Then 10 backwards steps with 8.5. Whoops, forget that one.
Win 10. Really. is about the best there’ll ever be. It almost runs\repairs itself.
I still have all the sets. and WIN official CD’s. from DOS 5 (7 x 3.5 discs) onwards. Just for nostalgia.
Threw out the floppy’s they started to crack round centres.
We didn’t even have Biro’s in school.
Class prefect. powder ink mixed daily and a bit of wood with a Broad\med\wide. NIB on the end of it.
Pencils were the modern world. and the END of decent freehand writing.
That NIB and it’s two little end bits. Completely control YOU.
Look at a modern fountain pen tip. Remove the two little balls on ends of the tips.
THAT’s what we wrote with.
Everything was a “scrawl” after that.
Sorry. just a little nostalgia.
I have “LOVE” Tattoo’d on my left knuckles. compliments of a darning needle and that school ink.
with a snake round a sword on wrist above it. AH the old days . Dumb as. Probably still am hey.
and rambling. just a little . (old age). don’t worry. You’ll ALL get it I hope.
One day.
And remember. EVERY day… is a good day.
There’s ALWAYS somebody worse off than you. Right to the second YOU die.
I can’t believe an Australian posted a recap of early computer development without mentioning Trumpet Winsock, Sacrilege! It was the best TCP/IP stack by far, and a product of the land of Oz.
I remember Trumpet Winsock! That was about the only reliable bit of operating system functionality on my Windows 3.1 box, presumably because it didn’t come from Microsoft. Never knew it came from Australia, though - you learn something new every day
Nah, don’t worry about it. Happy birthday when it comes
Definitely! I have a habit of visiting almost every open museum I pass by, and am always discovering new things, like the time I stumbled across the Joseph Priestley House in rural Pennsylvania USA. Joseph was one of the main proponents of your namesake theory, even after he discovered oxygen (and invented soda water), go figure:
Interesting guy, I dropped by the local cemetery to pay my respects after visiting his ex home. I’m sure he would have appreciated LED flashlights and come up with an interesting theory about how they worked, if he didn’t die too soon.
