MikeAusC
Enlightened
So IF the copper is half as thick as an Aluminium Star, both will have the same thermal conductivity from center to edge !
Why a good thermal path really matters
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So IF the copper is half as thick as an Aluminium Star, both will have the same thermal conductivity from center to edge !
ergotelis
Enlightened
Not exactly, the thermal path has to be good on all levels, a big 20mm board is useless if the led cannot transfer the heat as good as it has to.
Saablaster, did not forget you, but still haven't got all the boards from KD.
Saablaster, did not forget you, but still haven't got all the boards from KD.
Interesting but perhaps "obvious" result that did not need a ton of experimenting and probably could have been handled just fine by theoretical calculations ... with a lot less work.
I am not denying the need for a good thermal path. Certainly it is needed when you overdrive the LEDS more so Cree over Lumileds as Cree has more temperature related drop-off.
A few things you miss:
1) You "paint" all metal core with somewhat the same brush, which is very much not true. Your one picture example of a metal core board looks like it may be a very thin glass/epoxy board over top of a metal core. This is the poor mans metal core board and no one remotely serious about heat dissipation or with good knowledge of board construction and thermal performance would ever use this. Good metal core boards use a thermally conductive prepreg, not an epoxy glass composite.
Even within the thermal pre-preg group, there are several different types of differing thicknesses and composition. A thin layer with a high conductive material can offer performance 10-20 times your compared epoxy version. That said, sometimes you cannot use thin layers as you need more dielectric isolation.
Obviously a direct thermal connection to the heat sink is superior and there are companies that offer this as well.
2) Layout and even the type of LED do matter. Even with metal core boards, you can get a variety of thicknesses of the copper circuit layer. 4 ounce or even 8 ounce copper is obviously going to be superior to 1 ounce. Again this is even more true for Cree and Nichia with XP-E/G type designs as they have very little space for a thermal path from the LED. One of the reasons I like the Rebel is that I can have a much larger thermal path ... no electrical connections to get in the way.
That EXTECH meter you are going to buy is going to make little difference in the relative accuracy of your measurements (or likely absolute accuracy). In terms of absolutely accuracy, it has no LED setting, but realistically, tungsten and/or daylight will be good enough. All that switch does is compensate for known reading errors ONLY with known sources. The issue you run into with LEDS is the spectrum will change as they heat up and are over-driven. That meter will not compensate for that. Perhaps a truly high end meter from Minolta or Cooke will, but likely you are getting into spectrophotometer territory.
Semiman
I am not denying the need for a good thermal path. Certainly it is needed when you overdrive the LEDS more so Cree over Lumileds as Cree has more temperature related drop-off.
A few things you miss:
1) You "paint" all metal core with somewhat the same brush, which is very much not true. Your one picture example of a metal core board looks like it may be a very thin glass/epoxy board over top of a metal core. This is the poor mans metal core board and no one remotely serious about heat dissipation or with good knowledge of board construction and thermal performance would ever use this. Good metal core boards use a thermally conductive prepreg, not an epoxy glass composite.
Even within the thermal pre-preg group, there are several different types of differing thicknesses and composition. A thin layer with a high conductive material can offer performance 10-20 times your compared epoxy version. That said, sometimes you cannot use thin layers as you need more dielectric isolation.
Obviously a direct thermal connection to the heat sink is superior and there are companies that offer this as well.
2) Layout and even the type of LED do matter. Even with metal core boards, you can get a variety of thicknesses of the copper circuit layer. 4 ounce or even 8 ounce copper is obviously going to be superior to 1 ounce. Again this is even more true for Cree and Nichia with XP-E/G type designs as they have very little space for a thermal path from the LED. One of the reasons I like the Rebel is that I can have a much larger thermal path ... no electrical connections to get in the way.
That EXTECH meter you are going to buy is going to make little difference in the relative accuracy of your measurements (or likely absolute accuracy). In terms of absolutely accuracy, it has no LED setting, but realistically, tungsten and/or daylight will be good enough. All that switch does is compensate for known reading errors ONLY with known sources. The issue you run into with LEDS is the spectrum will change as they heat up and are over-driven. That meter will not compensate for that. Perhaps a truly high end meter from Minolta or Cooke will, but likely you are getting into spectrophotometer territory.
Semiman
Well of course the result is obvious. Being able to quantify the difference is what's key here. It is good to be able to actually see the differences in a way that is easily understood for the masses. Just using theoretical means is a less than desirable way to go about something like this. With true science theories are just the start. But you have to test them out to make sure. Theoretical calculations will never replace actual testing.
What these graphs do is allow someone who doesn't want to do a bunch of math
to very quickly see what the output of an LED would be given differing thermal solutions.Well you can think what you want as to whether or not I am painting all MCPCBs with the same brush but there is no denying that the very best performing MCPCB in the world will not compare to simply soldering straight to solid metal. Part of this thread will also be testing the various commonly available MCPCBs to see which ones perform better than others. The data will very clearly show that some are better than others so each one will get its own "brush" based solely on pure science.
I am trying to gather several different varieties of stars to do testing with so we all have good idea of what's available and the specific performance of each so we can be informed consumers. If you, or anyone, have some boards that you would like included in the test I'd be keen on getting one to test.
Find me a lightmeter more accurate than the Extech with datalogging at the price I paid for it or under($177) that also has the ability to refine with lighting type. You say the ability to change the lighting type won't make that much difference and you'd be right. These devices are already very accurate so there is not much room for improvement anyway. But I believe you'd be wrong to say that there is not going to be some advantage when I test both incands and then LEDs in my sphere. If I had the money for one of those insanely expensive meters I would buy it but I don't.
andersonEE
Newly Enlightened
Calculations are good...being able to see the results of our calculations is even better.
That is why I love CPF. Other flashlight/led/lumen nerds who post the results of their experiments for everyone to learn from.
I enjoy your threads, saabluster...and I am an electrical engineer who can do "calculations" with the best of them.
I seldom do math calcs anymore except for component values in circuits. After 40 + years
you develop a feel for what works or should work. My pet peeve is the 'Not Invented Here'
syndrome. Aquire the information developed by others, such as what saabluster does so well
and build on it. Real testing can sometimes show flaws in calculations do to unanticipated
factors. I do not have the time to explore all avenues in real time testing or to fine tune each
project to the n th degree. Keep up the good work, saabluster, and thank you.
Curt
you develop a feel for what works or should work. My pet peeve is the 'Not Invented Here'
syndrome. Aquire the information developed by others, such as what saabluster does so well
and build on it. Real testing can sometimes show flaws in calculations do to unanticipated
factors. I do not have the time to explore all avenues in real time testing or to fine tune each
project to the n th degree. Keep up the good work, saabluster, and thank you.
Curt
Well of course the result is obvious. Being able to quantify the difference is what's key here. It is good to be able to actually see the differences in a way that is easily understood for the masses. Just using theoretical means is a less than desirable way to go about something like this. With true science theories are just the start. But you have to test them out to make sure. Theoretical calculations will never replace actual testing.
What these graphs do is allow someone who doesn't want to do a bunch of math
No, what it does is show the results of your particular and potentially poorly implemented solution. To my point, there are many different metal core implementations, some very good, some very bad. Thickness and quality of your attachment method could have a major impact as well. Thickness of the copper layer. What LED you use (Rebel, Cree) all make a difference. You have just shown one method and one particular implementation of it that may have no basis for what someone else may do.
Show the way the thermal path is built up and hence understanding what does what, what can be improved, what makes little difference, etc. would be far more valuable to an experimenter. It also gives you something to work towards to see if you did it right.
In terms of best metal core, Laird makes what I have found to be some of the best commonly available material but I am not sure who would make a star based on it. I use it for product stuff.
The reason they have the switch is to deal with the inherent inaccuracies. Remember that refine is nothing more than a gain setting. It does not change the spectrum. Unfortunately (or fortunately), they do not have switches with a position for LEDS. They would not work if they did as there are so many different spectrums for LEDS. Even the fluorescent setting is really not right as there are a ton of spectrums for these as well. Depending on which LED you are using, the incandescent setting may be the best one to use. Unless the LED spectrum somewhat matches the spectrum of what you picked, then you may make the measurement better or worse compared to incandescent.
I do calculations more now than I have ever done. I would like to think that is growth in my maturity as an engineer. Yes I have a feel for what works and what will not, but I am sure many are surprised to find that a well implemented FR4 board with vias for say a Rebel, is better than a large portion of the metal core implementations even with thermal prepreg.
Sure you could do some test boards and MAYBE come to that conclusion. Of course, would I test 1, 2, 4, and 8 ounce copper? Would I try a variety of via sizes and via spacings? Would I try several plating thickness from my board vendor? No, I would build one or two different versions and perhaps come to the conclusion that FR4 does not work well. However, start doing calculations and you start to see what via sizes work best, what spacing, how that interacts with copper thickness (they are not exclusive of each other), etc. Doing a few test boards will never reveal to you how to improve this design. Your visibility into what is the limitation of the design will not be evident as there are too many intermixed variables in the physical implementation.
Yes real world testing often reveals mistakes in your hypothethis ..... especially if you have not spent enough time doing calculations, coming up with models, proving them out on paper, etc. The more you do on paper, the less you need to do on the bench normally and on the bench time is generally more expensive from a results standpoint. It is just like the programmers that dive right into programming without thinking about what they are going to do ... they end up taking twice as long with more bugs and less well structured and supportable code. The other issue of diving right into the bench without fully understanding the problem is that when things do not work as expected, you are not able to point to where the problem is and it is not uncommon for the problem to have nothing to do with the concept but everything to do with a mistake in implementation (manufacturing) and/or test setup.
I have 0 not invented here syndrome. Heck everytime I start on something I look to see what has been done similar before to see what I can learn, what issues they ran into, how to tweak the system, and almost always to understand the underlying concepts driving the design and the performance so that I can make mistakes on paper instead of in an actual design implementation. I know a ton about proper layout of analog and power supply circuitry, but I also love that my board layout package calculates parasitics as it makes for far fewer iterations and bench time to hit the targeted performance I am trying to achieve.
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Techjunkie
Enlightened
I've been curious to know something about the copper MCPCBs from DX... is the thermal pad of the XML soldered directly to the copper of the MCPCB through a window in the laminate layer? If not, is it possible to desolder the LED, srape off the laminate in the center, apply solder paste and reflow back onto the MCPCB? It seems to me that would eliminate the thermal insulation of the laminate layer.
Q#2: which XML stars have the thinnest laminate layer? (Are the KD stars in the running?)
Q#2: which XML stars have the thinnest laminate layer? (Are the KD stars in the running?)
MikeAusC
Enlightened
The DX copper MCPCBs have such thin copper it seems pointless.
If you're going to make the effort to solder an LED to copper, you may as well use a decent thickness of copper to spread the heat from the tiny area under the LED, to a much larger interface area with the heatsink.
If you're going to make the effort to solder an LED to copper, you may as well use a decent thickness of copper to spread the heat from the tiny area under the LED, to a much larger interface area with the heatsink.
My isn't your glass half empty. I should think given the results quite the obvious is on display. But twist it if you must.
Yeah some "good" some bad. So what. This will all become quite clear when the testing is done. I am not going to test every single LED out there and there is no reason to. What works with one LED will work with another. That being - decreasing the thermal resistance increases the performance of the LED. I am using what has started to become an industry standard for LED construction. Sure the K2, for instance, would not benefit as much from from some of these methods but those LEDs are dead or dieing. Welcome to the new world. It's not like some LEDs will see decreased performance from moving from a mcpcb to a heatpipe and there is no need to do calculations to figure that out. I am part of a clan here(Overdrivers) that likes to push things to the very boundaries. When doing this there is no need to do calculations. The solution is obvious. You simply do the absolute best you can thermally and call it a day. So while we would be done with our projects you'd still be tapping away at your calculator. Sure I get the need to do all those calculations when you are working with computers and designing boards and whatnot but what we do here is fairly simple and I feel the same way as Curt that I can do all those calculations in my head based on experience. In fact I designed and have built a light that has yet been made public trusting my experience alone to guide the way in designing the thermal path(and it is far from a normal solution) and after I built the light everything performed exactly as I expected it would.
Seriously? That is the point of this thread. Granted I have yet to do all the testing of various boards but I have clearly and repeatedly indicated I was going to. I have also mentioned the fact that I am going to be testing the ablated ceramic vs stock to see if there really is any benefit. If you are suggesting I make this thread into a boring science book about numbers you can forget about that. If you've followed my other threads you will know I am more about practical information. I have learned how to distinguish what needs to be learned and what serves merely to impress others. I am trying to show people merely what needs to be learned. You may feel otherwise and you certainly are most welcome to do so and certainly free to start your own calculations thread.
OK now show me a link to a product the average consumer here can buy that is a "good" product. Not a substrate a purchasable star that either has LEDs on it or can simply have them baked on and be done. Where are these wonderful boards you say exist because we would all like to start buying them.
So tell me. Does the switch adjust for the spectrum or adjust for color temp and how do you know?
No it does not have the LED direct to the bottom copper. It may be possible to do as you say. Why don't you do some calculations to find out because that will surely be far simpler than just trying it right?:laughing: Seriously I think that isn't a half bad idea but I think you might find it a little difficult as it appears to be the pre-preg stuff. I haven't messed with it yet though.
I agree. I was a little bit underwhelmed when I pulled it out of the package and realized just how much they scrimped on the copper. That said my intuition is that it will still be far far better than the Cutter boards. We shall see.
Techjunkie
Enlightened
Not familiar with the term "prepreg"... are you referring to the laminate layer? Is it different than the layer you peeled up from the cutter board in the pic above? If I were to attempt creating a window through it for the thermal pad, my first approach would be something abrasive, like a stone bit on my dremel. That will surely wouldn't create a perfectly flat surface, but solder should replace whatever is scraped away without creating a void between the emitter's center pad and the star. It can only be an improvement over the laminate, thermally.
Regarding the thinness of the 20mm copper star, the star's mass is less important than how fast a conduit it is to the heatsink beneath it, right? My expectation is that eliminating the thermally insulating laminate layer between the LED's center pad and the star, by soldering (the center pad only) directly to the star should make for less thermal resistance between the LED and the heatsink than any other 20mm star where laminate sits between it and all of the emitter.
Regardless of how thick a 20mm star is, the interface area with the heatsink beneath it will be the same. If my existing application calls for a 20mm star, and re-soldering the LED to a thin copper star after removing the laminate under the center thermal pad outperforms a conventional Aluminum star, or even the same Copper star with all the laminate in tact, then that doesn't seem pointless to me at all, and requires very little effort compared to a more custom solution.
If I were designing (and capable of manufacturing) everything from scratch, then obviously, there are more effective designs than the star, however, that requires far, far more effort than a simple de-solder, scrape and re-solder operation. I know my limitations. Tweaking the existing design is my forte, custom manufacturing something entirely new is not. I've tried my hand at creating completely custom parts with what tools I have at my disposal, and the results are seldom more rewarding than the results with the easy tweaks.
Laird Theramgon Tlam SS 1KA04 or DS 1KA06
http://www.lairdtech.com/Products/Thermal-Management-Solutions/Thermally-Conductive-PCB-Materials/
That said I have seen the data sheet for the Opulent thermal prepreg (many years ago) and I remember it being very good.
Before I started using any volume, I did my first ones the old fashioned way. I asked nicely for a bare board sample, and like any good hobbyist I rolled my own using my trusty printer and etched my own.
"What works with one LED will work with another." .... not true. I regularly use FR4 with vias for Luxeon Rebels and I used to use it for Cree XRE. I never use it for Cree XPE/XPG. Rebels and the XRE have a large thermal path that I can take advantage on on an FR4 board. On the XPE/XPG, there is almost no way I can spread the heat out on the surface, so I need to have a low thermal resistance downwards first and foremost.
"I am using what has started to become an industry standard for LED construction." ... and what would that be? Since last time I checked, LED on FR4, metal core, and direct thermal connection to the heat sink are all regularly practiced though you run into more patent issues with direct thermal contact unfortunately.
How do I know what those meters do? I asked! No no yesterday, but when I was looking at meters. They do not adjust for spectrum or color temperature. They simply adjust the gain (in s/w) based on a calibration done with standard sources .... which is great when you are measuring standard sources but no so great when you are doing other things.
You are contradicting yourself. You claim to be trying to achieve "the best possible". So why even discuss circuit boards? Best is direct solder and/or ultra thin high thermal conductivity glue direct to copper or even better a graphite/copper hybrid.
Yes seriously! Showing experimental results without understanding what they truly mean is useless. I did work with someone who had ruled out FR4 as being no good. What was really no good was his implementation.
Will there be an improvement between ablated ceramic and non ablated ceramic? ... of course there will be! Yes you can shave off the ceramic, hopefully you do not damage the part, hopefully you create the exact same thermal interface conditions with the non shaved and shaved version, etc. OR ... you could find out the material (or assume it is some aluminum/beryllium oxide derivative), find out the characteristics for that material, estimate the width of the thermal path, and then calculate fairly accurately how much improvement you will get thermally based on how much material is removed. That may sound complicated, but it really is not and it would not be susceptible to measurement error such as not having consistent mounting to the heat sink. The calculations will tell you it is worth doing (or not) and then you test it out. If it is not better in the test, then it is likely the test implementation, not the concept. However, if you just did tests, you could assume it was no better.
My glass is niether half full nor half empty.
I have worked with many good "feel" engineers and they are great when things are simple, easily understood and when you were not truly pushing the boundaries. However, their lack of proper methodology ususually was their (and ultimately the companies) downfall when things got complex and/or difficult.
Trust your experience ... I do too. But I am not arrogant enough to think that I do not make mistakes and/or I can't find better ways of doing things .... just like my GPS tells me often of routes I had not considered .... yet my experience sometimes knows that traffic will make certain of those routes unviable.
What was that assinine comment about the K2? In fact, older gen LEDs would benefit more from proper heat sinking that many new ones. Older LEDs generally had lower max Tjunction and they had worse output response w.r.t. temperature. The real change with new LEDs is that they are on small packages not much bigger than the die itself and hence you no longer have what is essentially a copper heat spreader. So yes now, more than ever it is important to get the LED connected to something that can spread the heat out as quickly as possible since your contact surface area is so small.
http://www.lairdtech.com/Products/Thermal-Management-Solutions/Thermally-Conductive-PCB-Materials/
That said I have seen the data sheet for the Opulent thermal prepreg (many years ago) and I remember it being very good.
Before I started using any volume, I did my first ones the old fashioned way. I asked nicely for a bare board sample, and like any good hobbyist I rolled my own using my trusty printer and etched my own.
"What works with one LED will work with another." .... not true. I regularly use FR4 with vias for Luxeon Rebels and I used to use it for Cree XRE. I never use it for Cree XPE/XPG. Rebels and the XRE have a large thermal path that I can take advantage on on an FR4 board. On the XPE/XPG, there is almost no way I can spread the heat out on the surface, so I need to have a low thermal resistance downwards first and foremost.
"I am using what has started to become an industry standard for LED construction." ... and what would that be? Since last time I checked, LED on FR4, metal core, and direct thermal connection to the heat sink are all regularly practiced though you run into more patent issues with direct thermal contact unfortunately.
How do I know what those meters do? I asked! No no yesterday, but when I was looking at meters. They do not adjust for spectrum or color temperature. They simply adjust the gain (in s/w) based on a calibration done with standard sources .... which is great when you are measuring standard sources but no so great when you are doing other things.
You are contradicting yourself. You claim to be trying to achieve "the best possible". So why even discuss circuit boards? Best is direct solder and/or ultra thin high thermal conductivity glue direct to copper or even better a graphite/copper hybrid.
Yes seriously! Showing experimental results without understanding what they truly mean is useless. I did work with someone who had ruled out FR4 as being no good. What was really no good was his implementation.
Will there be an improvement between ablated ceramic and non ablated ceramic? ... of course there will be! Yes you can shave off the ceramic, hopefully you do not damage the part, hopefully you create the exact same thermal interface conditions with the non shaved and shaved version, etc. OR ... you could find out the material (or assume it is some aluminum/beryllium oxide derivative), find out the characteristics for that material, estimate the width of the thermal path, and then calculate fairly accurately how much improvement you will get thermally based on how much material is removed. That may sound complicated, but it really is not and it would not be susceptible to measurement error such as not having consistent mounting to the heat sink. The calculations will tell you it is worth doing (or not) and then you test it out. If it is not better in the test, then it is likely the test implementation, not the concept. However, if you just did tests, you could assume it was no better.
My glass is niether half full nor half empty.
I have worked with many good "feel" engineers and they are great when things are simple, easily understood and when you were not truly pushing the boundaries. However, their lack of proper methodology ususually was their (and ultimately the companies) downfall when things got complex and/or difficult.
Trust your experience ... I do too. But I am not arrogant enough to think that I do not make mistakes and/or I can't find better ways of doing things .... just like my GPS tells me often of routes I had not considered .... yet my experience sometimes knows that traffic will make certain of those routes unviable.
What was that assinine comment about the K2? In fact, older gen LEDs would benefit more from proper heat sinking that many new ones. Older LEDs generally had lower max Tjunction and they had worse output response w.r.t. temperature. The real change with new LEDs is that they are on small packages not much bigger than the die itself and hence you no longer have what is essentially a copper heat spreader. So yes now, more than ever it is important to get the LED connected to something that can spread the heat out as quickly as possible since your contact surface area is so small.
Techjunkie,
I agree, the thickness of the copper is pretty meaningless for what you are doing. It's all about reducing the thermal resistance between the LED and primary heatsink and the air. \
That said, I think that SAA's complaint was about the copper circuit layer. Thicker surface copper will spread the heat more sideways so there is less resistance downwards into the metal core. For some LEDS, that can be highly advantageous, for some it does not make as much of a difference.
YES ... let's do some calculations!
I don't know the material, but I will assume it is relatively good, 0.5 C/cm2/watt.
Assume Cree XPG/XPE which has a thermal pad 4.4mm2. I am going to assume some reasonable heat spreading and say the effective heat path is 8mm2. If I knew the copper thickness I could make a better calculation.
So the thermal resistance is going to be 0.5 * 100/8 = 6C / watt. I would say that is best case and it could be as bad as 0.8 * 100 / 6 = 13C / watt. Most likely it is in the middle. If you are pumping 5 watts into LED, a 30-50C decrease in LED temp may be possible.
I actually took a little closer look at it and scraped the top away and it appears to be some sort of ceramic dielectric. Alumina probably but I couldn't tell you what exactly. It should be far better than the Cutter boards at any rate.
You are correct that mass has nothing to do with it. A heatpipe has very little mass but can transfer heat exceedingly efficiently. I say go right ahead and try your idea. If you can do it right and not gouge the underlying copper you will definitely see improved performance. I just don't think it will be very easy.
vaska
Newly Enlightened
It's a pity that a thread, where a discussion on different aluminium PC boards took place, is lost. There I wrote about what level of thermal conductivity one can achieve if he bothers to make PCB design of his own. Here in Moscow local manufacturers offer different materials for PCB design, and the best combination available is like this: Al1100 alloy with 222 W/(m*K) thermal coductivity, 0,05 mm thin insulation layer with 1,8 W/(m*K) conductivity and copper layer 0,07 mm thin. Thickness of copper layer matters when you are trying to enlarge effective area for heat dissipation through insulation layer which has the least thermal conductivity among named materials. This picture illustrates difference between poor (left) and competent (right) design.
I'm too lazy to make calculations again, but I remember that total conductivity estimation was near 2 W/K for XM-L on 2 mm thick PCB 22 mm in diameter. It could be much less if I ordered PCBs with 0,140 mm or even 0,35 mm copper layer, but there were some technological difficulties.
So, looking at Lux-rc's attempts of optimising thermal qualities of PCB, I thought that they are not worth charges.
I'm too lazy to make calculations again, but I remember that total conductivity estimation was near 2 W/K for XM-L on 2 mm thick PCB 22 mm in diameter. It could be much less if I ordered PCBs with 0,140 mm or even 0,35 mm copper layer, but there were some technological difficulties.
So, looking at Lux-rc's attempts of optimising thermal qualities of PCB, I thought that they are not worth charges.
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Hey nice link to some stars there. :shakehead
Yes I suspect they will do quite well. For an mcpcb.
I suppose it is within the realm of possibility for people here to make their own boards but it is out of the reach of most everyone here to do. Of course so is some of what's on display in this thread.
That's some rather selective quoting going on there. Why don't we add back in what came directly after it.
" That being - decreasing the thermal resistance increases the performance of the LED. "
But then you can't argue with that now can you.
I am not referring to the boards. I am referring to the construction of the LED itself. With the LED die directly attached to ceramic unlike what was the old standard of being mounted on a chunk of copper. Standardizing on one LED for these tests is the proper and sensible thing to do. I am also using what is one of the most common LEDs seen in these parts so the results are quite relevant.
Should be interesting to see if they tell me the same thing. Thanks for info.
Multiple reasons. Stars are the most common way to mount LEDs here. So much so that some people(annoyingly so) simply refer to the whole assembly as an "LED". Just showing the results of mounting an LED on a heatpipe and calling it a day gives people no sense of where that stands in relation to other solutions. So it is therefore useless information. However testing the various solutions out there and posting the data will help people to clearly see where each solution lies relative to one another.
Second, "the best possible" is different with each build. Different lights impose different design restraints and they may be forced to use something other than a heatpipe. If it is the case that they will be beholden to the use of mcpcbs then they need to know what is the "best possible" for that situation.
You can call my tests useless but that is one opinion. One I do not share.
OR you could just do it and find out. You have your way and I have mine.
Well I say it is more complicated than just testing it in real life. If the other works for you great. It will not work for me and frankly I don't want to go that route. Actual testing is far far more interesting. I enjoy that side of the hobby at least as much as I do the lights themselves.
I would agree with you if we were designing flashlights for a virtual world but we aren't. You say calculating first would be superior because you remove the possible error or deviation that can occur in real life application but ignore that the world we live in and the products we use are based on actual implementation where there can and are variances in our results. Therefore the best way to know real world results is to make real world tests.
I get what your saying about the fact that calculations can show potentially bad implementation but I really think you are presuming that I don't know proper implementation. You'd be wrong. I also think you are severely over thinking our hobby. Again, on an industrial level dealing with very complex components sure. Then I would agree with everything you are saying. Not here however.
So how many were flashlight designers?
I have never claimed infallibility. So thank you so much for opening my eyes to the wonderful world of theoretical calculations. Since you are not arrogant then you will realize there is often more than one way to skin a cat.
That was in response to your saying that what LED you use makes a difference. As if my use of a K2 for instance would result in entirely different results. It was just used as an example. Sure the results would be different but the underlying principle is always the same. The cooler the LED the better it performs.
Do you have a link to where these fancy boards could be bought? I'd love to test them.
If Lux-rc is putting that chunk of solid metal in salable product with a direct attach point then I have a lot of respect for them.
vaska
Newly Enlightened
As far as I know, it's not finished yet: in plans is thin PCB with holes for chunks stuck to the top of the "pill".
He's going to. His name is Serge and he is a good engineer, very good technologist and a nice guy who'll surely give you his patterns for experiments free of charge
His site
