I could be wrong, but I’ve got a feeling it could be a significant price difference for a good boost driver compared to a FET +1 driver, in terms of Chinese production cost.
Lexel said it would cost over $20 for him to make a high powered 17 mm boost driver.
In a BLF project it could be cheaper:
- increasing driver size would enable use of cheaper components
- labour in China is cheaper
- larger scale saves a lot
So…I don’t know, but maybe up to $10 premium?
Then there’s a question of what LED would be involved.
- XHP35 is quite expensive considering its output. The work-in-progress drivers can drive it to the full potential
- XHP50.2 is a bit more expensive per unit, but cheaper per-lumen. The work-in-progress drivers can drive it reasonably hard, but not to the limit
- XHP70.2 is actually quite cheap per-lumen, but the work-in-progress drivers wouldn’t be able to drive it hard
- Some Nichia? Luxeon?
- Multiple 3V LEDs?
Here is what Lexel just told me:
So driver parts alone cost over double a good FET driver like in the FW3A.
Up to 25W?…That’s XHP35 driven to 1.8A. Could wish for more. 
Sounds like a 25W boost driver is good enough for a single-emitter light. Only 6€ more than a good FET+AMC driver doesn’t sound like much more expensive. So, it would be a $30 or $40 light, rather than a $20 or $30 light? Still a bargain compared to most boost-driven lights you can buy. Even if the price was $50 for a boost driver + a XHP50.2, that’s only half of what a similar Zebralight costs. Maybe the features or quality wouldn’t be as high, but BLF designs tend to be pretty good.
Area under the curve says H17F wins, but they both seem to end up at the same place, steady-state. (Physics).
Perhaps down to the slightly higher thermal mass of the Cu torch, but thermal mass is not the same as mass (though I do like a heavy Cu torch).
For an identically dimensioned torch, made of either Al or Cu, the Cu torch will weigh 8940/2712 = 3.3 times as much.
Whereas the Al has more than double the specific heat capacity of Cu (0.22 vs. 0.1) by mass, or 2.2/3.3 = 0.67 by volume, but half the thermal conductivity.
Which is why copper torches make little sense in engineering terms, over three times as heavy for marginal gains. They are shiney though and patinate nicely.
If you want thermal mass, with low actual mass, go Al, not Cu.
Get it right, and you’ll have better thermal conductivity too, with less mass.
Edit: small bits of copper used in the right place for thermal conductivity are excellent, MCPCBs and pills. But making a whole torch out of it is a bit silly. And kidding yourself that it adds “thermal mass” without a downside (actual mass) doesn’t fit the facts.
Brass of course is one of the worst possible things to use for removable pills, Convoy etc. please note. A proper integral Al shelf is far better.
Please , put me in for two
Tom Tom: Not everyone is a ultralight enthusiast; sometimes volume is all that matters. Higher conductivity and heat capacity for the same size light is great. Were it not for the price and how much more usable aluminum is as a material, copper would be great.
spaceminions copper just makes flashlight non-EDC
Oh good, that means I’m not going crazy. I wrote EDN, then looked at your link and it was just Electronic Design. I edited my previous post lest anyone think I subscribed to Erectile Dysfunction magazine.
/\ … 
Not that there’s anything wrong with that for those that may be suffering………not that I would know about such an affliction but just trying to lend support to those who might be feeling a little less frivolous and………oh, god, there’s no way out of this, is there?
Sildenafil ?
Too cheap to bother charging from some sympathetic pharmacists. And an understanding GP.
Just the private prescription fee, £7 for 16 100 mg tabs.
Edit: I have been told that 50 mg is enough, and the generic 100 mg tabs are set up to be easily divided.
Not that I would need anything like that, just saying, heard about this from a friend …
Duplicate post
Repeated request
You’re nº 1379 and 1380 -of pepinfaxera list of interest page 111
For a total of 2 lights .
How many flashlights do you want in total? … x … units? .
.
Edit
Jul 4 nd I receive Personal Message (PM) from Roc32:
You’re nº 1388 and 1389 of pepinfaxera list of interest page 111
For a total of 2 lights .
You are number No. # 366 on: Interest List , Post # 4 , ” Page 1 , “:FW3A, a TLF/BLF EDC flashlight - SST-20 available, coupon codes public - #4 by FW3A_Team :
For a total of 1 lights .
How many flashlights do you want in total? … x … units? .
.
.
Edit ;
Jul 4 nd I receive Personal Message (PM) from Silentcropduster:
Hahaa spaceminions! :+1: I knew this would stick…… CRI Baby!
Can you post a pic of your card?
I have 2-3 High CRI emitter lights :person_facepalming: …just a Fetus…
The results aren’t really comparable, since the H17F’s host had quite a bit more thermal mass than a D4. I’d have to measure them in the same host, or at least the same model, for comparable results. It might happen at some point, but that’s a lot of effort just to satisfy my curiosity about whether the H17F can adjust any faster or if what I saw was its fastest speed.
Hey don’t look backwards at what you are doing. Just drive forwards. Whilst understanding the back history.
I think there is a lot more to come with firmware/driver integration, but the driver hardware will have to become a lot better, not sure if this is understood, or whether anyone cares.
Interested in three.
Not entirely sure yet. I think Neal has that process covered, but I don’t know the details.