[PART 1] Official BLF GT Group Buy thread. Group buy officially closed! Lights shipping.

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Texas_Ace
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Hmm, I don’t claim to be an expert on the subject at all, I just don’t think we are that close to truly “maxing out” LED tech.

I have never really researched it though so I have nothing hard to go on besides that.

I could very well be wrong and we will have to start looking for new lighting tech in 5 years.

DavidEF
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Texas_Ace wrote:
Hmm, I don’t claim to be an expert on the subject at all, I just don’t think we are that close to truly “maxing out” LED tech.

I have never really researched it though so I have nothing hard to go on besides that.

I could very well be wrong and we will have to start looking for new lighting tech in 5 years.


Well, just remember that Cree hit the 300 lm/w efficiency at a very low current. So, of course, there can still be improvements just by making the efficiency go up in higher current scenarios. A “perfect” LED would have to be one that could never burn out at any current. If there’s no heat, how could it? So, there is definitely a long way to go still. Wink

The Cycle of Goodness: “No one prospers without rendering benefit to others”
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Gerrit
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I still vote for your design fritz. Its really an elegant flashlight.

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fritz15 wrote:
Wow, that’s amazing!

I like it a lot. Which file formats can you export? Maybe I could perform a thermal analysis of your model. It would be interesting to know if it maybe performed better than mine.

The 300 lumens per watt is, as far as I understood it correctly, the maximal theoretical value a white led can reach (wikipedia). At this point the led would have a efficiency close to 1 or 1. Now if a led puts out around 150 lumens per watt it would have half the efficiency of a perfect led and consequently around 0.5.

But you are right, the way leds are driven here they are less efficient. But hey, our numbers agree here so it sounds about right. Thumbs Up

Sorry, you’re reading that wrong. https://en.wikipedia.org/wiki/Luminous_efficacy
100% luminous efficacy is 683lm with 1W.
The theoretical maximum of an LED is 260-300 which it says right beside is 38.1%-43.9% efficiency.

Driving an XHP70 at 12A requires 7.5v, which is 12*7.5=90W. At this current it produces slightly over 5000lm, so you get 5000/90 = 55.6lm/W
If you look on the wikipedia page, in the first chart, 54.7lm/W is 8% efficiency. So basically for the XHP70 7.2W are turning into light, and 82.8W are going into heat.

fritz15
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Enderman wrote:
fritz15 wrote:
Wow, that’s amazing!

I like it a lot. Which file formats can you export? Maybe I could perform a thermal analysis of your model. It would be interesting to know if it maybe performed better than mine.

The 300 lumens per watt is, as far as I understood it correctly, the maximal theoretical value a white led can reach (wikipedia). At this point the led would have a efficiency close to 1 or 1. Now if a led puts out around 150 lumens per watt it would have half the efficiency of a perfect led and consequently around 0.5.

But you are right, the way leds are driven here they are less efficient. But hey, our numbers agree here so it sounds about right. Thumbs Up

Sorry, you’re reading that wrong. https://en.wikipedia.org/wiki/Luminous_efficacy
100% luminous efficacy is 683lm with 1W.
The theoretical maximum of an LED is 260-300 which it says right beside is 38.1%-43.9% efficiency.

Driving an XHP70 at 12A requires 7.5v, which is 12*7.5=90W. At this current it produces slightly over 5000lm, so you get 5000/90 = 55.6lm/W
If you look on the wikipedia page, in the first chart, 54.7lm/W is 8% efficiency. So basically for the XHP70 7.2W are turning into light, and 82.8W are going into heat.

No, the 683lm are for 555 nm. For a different wavelength this value is lower.

Enderman
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fritz15 wrote:

No, the 683lm are for 555 nm. For a different wavelength this value is lower.


It says for an LED that 300lm is 43.9% efficiency.
300/0.439 = 683.4lm
So that means an LED working at peak efficiency 300lm/W will only be converting 43.9% of the power into light.
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Enderman wrote:
fritz15 wrote:

No, the 683lm are for 555 nm. For a different wavelength this value is lower.


It says for an LED that 300lm is 43.9% efficiency.
300/0.439 = 683.4lm
So that means an LED working at peak efficiency 300lm/W will only be converting 43.9% of the power into light.

I quote the first sentence in the wikipedia article

Quote:
Luminous efficacy is a measure of how well a light source produces visible light.

So for green the Luminous efficacy is 100%. That means we see green light best. However, we don’t see other wavelengths as good as green. So what we perceive as 683 lm in green, we just perceive as around 300 lm in a different wavelength.

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fritz15 wrote:

Here is a thermal analysis with 120 Watts of heat, 20 degrees ambient temperature and a convection coefficient of 27:

*Unfortunately I can’t perform an analysis x minutes after applying the heat. *


Same number used as fritz15, only the model has changed.
Total time is 600 seconds, time steps are 60 seconds.
(pictures are cross-sections, click for full version)
Here it is with 40 watts:

Here it is with 120 watts:


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I feel that Fritz15’s design is most pleasing on the eyes – the most harmonious design – and it has the possibility to mount carrying handel. I really like that.
Not a very big flashlight, but a searchlight.
.
Having said that, I could certainly live with 5AR’s design Wink
And a well meant suggestion on that design: the head is, of course, very big and the body relatively small.
No problem, that is the basic design that was agreed upon.
However, it could be made more aesthetically hormonious by adding a much larger tailcap, in which anti-roll could be incorporated, no?
.
Just a suggestion, of course Thumbs Up

Grtz
Nico

Texas_Ace
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Nicolaas wrote:
I feel that Fritz15’s design is most pleasing on the eyes – the most harmonious design – and it has the possibility to mount carrying handel. I really like that.
Not a very big flashlight, but a searchlight.
.
Having said that, I could certainly live with 5AR’s design Wink
And a well meant suggestion on that design: the head is, of course, very big and the body relatively small.
No problem, that is the basic design that was agreed upon.
However, it could be made more aesthetically hormonious by adding a much larger tailcap, in which anti-roll could be incorporated, no?
.
Just a suggestion, of course Thumbs Up

Grtz
Nico

All of the lights will have the ability to use a tripod mounted carry handle. None of them will come with any other form of handle.

EasyB
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Enderman wrote:
fritz15 wrote:

No, the 683lm are for 555 nm. For a different wavelength this value is lower.


It says for an LED that 300lm is 43.9% efficiency.
300/0.439 = 683.4lm
So that means an LED working at peak efficiency 300lm/W will only be converting 43.9% of the power into light.

I think fritz15 is right. The 683lm/W is for 555nm light, and this is practically irrelevant for us because our LEDs are “white”. The luminous efficacy depends on the spectrum, so that efficiency column in the wikipedia article is misleading because it compares every luminous efficacy to that of 555nm light, which hardly relevant.

The 260-300 lm/W value for LEDs is the theoretical maximum given the typical LED spectrum (blue peak and a yellowish peak) and it represents 100% conversion of input power to photons.

Texas_Ace
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EasyB wrote:
The 260-300 lm/W value for LEDs is the theoretical maximum given the typical LED spectrum (blue peak and a yellowish peak) and it represents 100% conversion of input power to photons.

It seems we know that is not the case since LED’s making those kind of numbers still get hot, thus not all the power is going to photons?

EasyB
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Texas_Ace wrote:
EasyB wrote:
The 260-300 lm/W value for LEDs is the theoretical maximum given the typical LED spectrum (blue peak and a yellowish peak) and it represents 100% conversion of input power to photons.

It seems we know that is not the case since LED’s making those kind of numbers still get hot, thus not all the power is going to photons?

This is the reference wikipedia quotes for the 260-300lm/W number and it explains with a bit more context:
http://phys.org/news/2010-08-white-super-high-luminous-efficacy.html

They have made white LEDs close to the theoretical efficiency, but only with very small outputs. I can see why you might be a bit skeptical that it would produce very little heat (proportionally), but it looks like it is the case.

Edit: here is another reference from that wikipedia page: https://arxiv.org/abs/1309.7039
They calculate the maximum efficacy of truncated black body spectra; they only consider the part of the spectrum that is within the visible wavelength range. They get numbers around 250-350lm/W. A truncated black body spectrum is approximately what a white LED spectrum looks like; light is only produced in the visible range.

Koenta
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This light deserves a beautiful designed BLF GT logo. I don’t really like the current logo Oops

Texas_Ace
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Koenta wrote:
This light deserves a beautiful designed BLF GT logo. I don’t really like the current logo Oops

It could indeed use a nice logo, if people want to come up with ideas a poll can be held for that later

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Allright guys, i’m done wrestling with the pixels…
Must say i ran into the limits of what i work with quite often, and still i had many many options, but i think it ain’t half bad like this:

The shelf for the LED sits in the middle of the fins.

Simple lines, not only because it’s very difficult (for me) to do otherwise, but also with the production costs in mind.
And i like simple lines too. Smile

The anti rolling blocks are now milled into the head, which is easier to do properly.

This is with a 100mm deep reflector.

I hope you like it, although i only have this simple view of it, i have no 3D model.

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Nice work Jerommel ! These are all really sweet.

Koenta
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Nice pics Jerommel, I like the one on the right the most. Albeit you put a lot of effort in it I have to confess I like Fritz 15 light more. But as you say, yours will be easier to manufacture, less milling.

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Koenta wrote:
Nice pics Jerommel, I like the one on the right the most. Albeit you put a lot of effort in it I have to confess I like Fritz 15 light more.
Maybe i do too. Smile
I do think though he should swap the finned part with the ring part of the ‘light engine’.
Should be simple to do i.m.o.
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5ar, your renderings are awesome. Thumbs Up

thijsco19
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Here is my design.
All pictures are clickable.



- Shoulder strap connections on head and battery tube
- Tripod mount at exact the Center of Mass (Center of mass is the black and white mark in the pictures)
- Side switch (IMO there is no reason for tailswitch, but can be made)
- Imaging the battery tube with full knurling
- I left some room above the battery carrier because there are no battery springs, the room should make up for that
- There is a pocket especially for the led (26mm diameter)
- Driver pocket (45mm diameter in this design)
- Head consists of 2 parts for easy modding, light can be used as a candle without top part
- Good thermal characteristics

5ar you can use this picture to photoshop it next to fritz and your light for comparison.

The Miller
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wauw, I cannot choose so leave the voting for now Wink
And well I slipped in a little design of my own Big Smile

POLL for basic design overview.
http://budgetlightforum.com/node/51246

Jerommel
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Potato powerrrrrr…..! Big Smile

thijsco19
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I think you’ll need a whole lot of potato’s to power up the XHP35 at 2.5 A. Big Smile

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yeah I am very proud of making such a “different” design Big Smile

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Too late to say I’m interested in one of these? Looks awesome, no matter which design we go with.

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pooptoast wrote:
Too late to say I’m interested in one of these? Looks awesome, no matter which design we go with.

As long as you vote for design 2 you can still get in Wink

P.S. Or any other design actually but design 2 is what this light should look like….lol

Unlike Miller I have no issues at all with voicing my opinion on the matter, not like anyone doubts it for a moment anyways.

Design 2 power! Cool

The Miller
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Lol
Yes will update list later
Just choose what you like most but it will not be the potato Wink

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Every designer, and especially potato-power (LOL), have done an amazing job!!! BRAVO!! Big Smile

When will the poll be closed?

"Do to others, what you would like others do to you.."

-MortyDuck-

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The Miller wrote:
Lol Yes will update list later Just choose what you like most but it will not be the potato Wink

I am heartbroken, that was my backup plan, it would be the ultimate survival light, once the light died you could eat it!

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