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Why do LEDs generate heat?
Why do LEDs generate heat? I want a technical answer not "because they're inefficient". And will we ever make them more efficient?
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Why do LEDs generate heat?
On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote:
Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just lioke why does a wire get hot when curremnt passes through it. And will we ever make them more efficient? Probably. |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote:
On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just lioke why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance and if it can be overcome by using different materials. And are you sure it's even resistance? It could be some photons are reabsorbed before they escape the LED, generating heat. And will we ever make them more efficient? Probably. |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 14:29:30 +0100, Commander Kinsey wrote:
Why do LEDs generate heat? I want a technical answer not "because they're inefficient". And will we ever make them more efficient? I got useful answers from Quora: "LEDs are ever more and more efficient. In the last 40 years, tremendous strides have been made. They generate heat because they are conducting electricity through semiconductors. Unlike metals which have very little resistance to electric currents, semiconductors offer more resistance. Not as much as true nonmetals, but still more than metals. It is the resistance of the semiconductor layers, both N and P, and the resistance of the junction itself, that generate the heat." "Every electronic device is less than 100 percent efficient. On a low level, it is due to the law of probability, or as the physicists call it, entropy. The odds of all those electrons conveying their energy into photons is very low. Some are always making random transitions, generating heat instead of light." |
Why do LEDs generate heat?
On Thursday, 3 October 2019 14:45:38 UTC+1, Commander Kinsey wrote:
On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just like why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance. Every conductor has resistance apart from perhaps a superconductor. yuo also have theb curent passing from one type of conductor to another. One of those conductors will convert the energy to light and heat. They won;t create much IR or UV because the material chosen was chosen because it emits the required wavelengh of light and not much eles. and if it can be overcome by using different materials. No they have been trying for years and until someone can come up with a magic substance that has zero resistance that is. And are you sure it's even resistance? It could be some photons are reabsorbed before they escape the LED, generating heat. No that would be IR 'heat' , and why would photons be re-absorbed anyway ? And will we ever make them more efficient? Probably. |
Why do LEDs generate heat?
On Thursday, 3 October 2019 14:49:47 UTC+1, Commander Kinsey wrote:
On Thu, 03 Oct 2019 14:29:30 +0100, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". And will we ever make them more efficient? I got useful answers from Quora: "LEDs are ever more and more efficient. In the last 40 years, tremendous strides have been made. They generate heat because they are conducting electricity through semiconductors. Unlike metals which have very little resistance to electric currents, semiconductors offer more resistance. Not as much as true nonmetals, but still more than metals. It is the resistance of the semiconductor layers, both N and P, and the resistance of the junction itself, that generate the heat." pretty much what I"ve just said. without Quora. "Every electronic device is less than 100 percent efficient. On a low level, it is due to the law of probability, or as the physicists call it, entropy. The odds of all those electrons conveying their energy into photons is very low. Some are always making random transitions, generating heat instead of light." |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 15:01:34 +0100, whisky-dave wrote:
On Thursday, 3 October 2019 14:49:47 UTC+1, Commander Kinsey wrote: On Thu, 03 Oct 2019 14:29:30 +0100, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". And will we ever make them more efficient? I got useful answers from Quora: "LEDs are ever more and more efficient. In the last 40 years, tremendous strides have been made. They generate heat because they are conducting electricity through semiconductors. Unlike metals which have very little resistance to electric currents, semiconductors offer more resistance. Not as much as true nonmetals, but still more than metals. It is the resistance of the semiconductor layers, both N and P, and the resistance of the junction itself, that generate the heat." pretty much what I"ve just said. without Quora. The answers I pasted were far more detailed. I did say I wanted a technical answer. "Every electronic device is less than 100 percent efficient. On a low level, it is due to the law of probability, or as the physicists call it, entropy. The odds of all those electrons conveying their energy into photons is very low. Some are always making random transitions, generating heat instead of light." |
Why do LEDs generate heat?
On 03/10/2019 14:45, Commander Kinsey wrote:
On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey* wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just lioke why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance and if it can be overcome by using different materials.* And are you It is resistance in the sense that there is some frictional losses to the movement of current in the crystal lattice. Early LEDs you could bump up the quantum efficiency by stiffening it - immersing in LN2 worked a few times before thermal cycling killed it stone dead. sure it's even resistance?* It could be some photons are reabsorbed before they escape the LED, generating heat. White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. For comparison a tungsten light bulb is only about 2% efficient at making visible light. And will we ever make them more efficient? Probably. Quantum efficiency and efficacy of LEDs has been improving with time. Cree have production models at 100Lm/W another factor of 2.5 improvement is theoretically possible and the odd sample has been made but the problems of making such a device in production quantities isn't cost effective at present. Cost per lumen and total flux graphs show how much improvement there has been since the first LED indicators in 1970. https://en.wikipedia.org/wiki/Light-...bre akthrough -- Regards, Martin Brown |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 14:58:46 +0100, whisky-dave wrote:
On Thursday, 3 October 2019 14:45:38 UTC+1, Commander Kinsey wrote: On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just like why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance. Every conductor has resistance apart from perhaps a superconductor. yuo also have theb curent passing from one type of conductor to another. I assumed that the layers were so thin, resistance should be minimal. I guess transistors are the same and they get hot. Semiconductors probably have quite a high resistance? One of those conductors will convert the energy to light and heat. They won;t create much IR or UV because the material chosen was chosen because it emits the required wavelengh of light and not much eles. and if it can be overcome by using different materials. No they have been trying for years and until someone can come up with a magic substance that has zero resistance that is. Well they've certainly improved the efficiency over the years. The question is how far can they get without using them at absolute zero? Or perhaps even a completely different way of generating light? And are you sure it's even resistance? It could be some photons are reabsorbed before they escape the LED, generating heat. No that would be IR 'heat' , and why would photons be re-absorbed anyway ? Because they might not come out of the LED into the room, but hit another part of it internally. |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 15:08:43 +0100, Martin Brown wrote:
On 03/10/2019 14:45, Commander Kinsey wrote: On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just lioke why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance and if it can be overcome by using different materials. And are you It is resistance in the sense that there is some frictional losses to the movement of current in the crystal lattice. Early LEDs you could bump up the quantum efficiency by stiffening it - immersing in LN2 worked a few times before thermal cycling killed it stone dead. sure it's even resistance? It could be some photons are reabsorbed before they escape the LED, generating heat. White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. I didn't realise that, I thought white LEDs were designed to directly emit a handful of different visible light wavelengths to make white. Is there a reason this can't be done? An LED can make anything in the visible light spectrum, so surely a mixture of them would be more efficient than using phosphors? There could even be seperate LEDs within the housing, like growlamps which have visible, IR, and UV LEDs. For comparison a tungsten light bulb is only about 2% efficient at making visible light. And will we ever make them more efficient? Probably. Quantum efficiency and efficacy of LEDs has been improving with time. Cree have production models at 100Lm/W another factor of 2.5 improvement is theoretically possible and the odd sample has been made but the problems of making such a device in production quantities isn't cost effective at present. Cost per lumen and total flux graphs show how much improvement there has been since the first LED indicators in 1970. https://en.wikipedia.org/wiki/Light-...bre akthrough That graph looks very promising. |
Troll-feeding Senile ASSHOLE Alert!
On Thu, 3 Oct 2019 06:37:34 -0700 (PDT), whisky-depraved, the notorious,
troll-feeding, senile idiot, blabbered again: That is the technical answer just lioke why does a wire get hot when curremnt passes through it. And will we ever make them more efficient? Probably. Trust that you senile ****** will be the first to take that attention-starved ******'s latest bait! tsk |
Why do LEDs generate heat?
On Thursday, 3 October 2019 15:10:44 UTC+1, Commander Kinsey wrote:
On Thu, 03 Oct 2019 14:58:46 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:45:38 UTC+1, Commander Kinsey wrote: On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just like why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance. Every conductor has resistance apart from perhaps a superconductor. yuo also have theb curent passing from one type of conductor to another. I assumed that the layers were so thin, resistance should be minimal. Depending on yuor refernce point for thin and minimal. I guess transistors are the same and they get hot. Semiconductors probably have quite a high resistance? Well yes compared to low or zero. One of those conductors will convert the energy to light and heat. They won;t create much IR or UV because the material chosen was chosen because it emits the required wavelengh of light and not much eles. and if it can be overcome by using different materials. No they have been trying for years and until someone can come up with a magic substance that has zero resistance that is. Well they've certainly improved the efficiency over the years. The question is how far can they get without using them at absolute zero? Or perhaps even a completely different way of generating light? There's bio-luminescence and using a lattice structure like butterfly wings that could be used and have been used in high end modern displays. But bio-luminescence is diffiuclt to control at speed. And are you sure it's even resistance? It could be some photons are reabsorbed before they escape the LED, generating heat. No that would be IR 'heat' , and why would photons be re-absorbed anyway ? Because they might not come out of the LED into the room, but hit another part of it internally. White LEDs do that and some other colours but I doubt much heat is generated. |
Troll-feeding Senile ASSHOLE Alert!
On Thu, 3 Oct 2019 06:58:46 -0700 (PDT), whisky-depraved, the notorious,
troll-feeding, senile idiot, blabbered again: FLUSH the senile asshole's latest idiotic **** Starting another one of your notorious retarded "conversations" with the sociopath, you senile asshole? BG |
Troll-feeding Senile ASSHOLE Alert!
On Thu, 3 Oct 2019 07:58:27 -0700 (PDT), whisky-depraved, the notorious,
troll-feeding, senile idiot, blabbered again: White LEDs do that and some other colours but I doubt much heat is generated. What you two PRIZE idiots keep generating here is ENDLESS IDIOTIC BULLSHT! |
Troll-feeding Senile IDIOT Alert!
On Thu, 3 Oct 2019 15:08:43 +0100, Martin Brownnoser, another troll-feeding,
senile idiot, blathered: https://en.wikipedia.org/wiki/Light-...bre akthrough The trolling ****** thanks you nicely for yet another big load of troll-fodder, you demented troll-feeding senile asshole! tsk |
Troll-feeding Senile ASSHOLE Alert!
On Thu, 3 Oct 2019 07:01:34 -0700 (PDT), whisky-depraved, the notorious,
troll-feeding, senile idiot, blabbered again: FLUSH the two prize idiots' usual bull**** unread again So for how long are you two prize idiots going to go on like this, this time? A few days? A few weeks again? Bunch of mentally disturbed idiots! tsk |
Why do LEDs generate heat?
One obviously has inefficiencies or the perpetual motion machine would be
everywhere. Brian -- ----- -- This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... Blind user, so no pictures please Note this Signature is meaningless.! "whisky-dave" wrote in message ... On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just lioke why does a wire get hot when curremnt passes through it. And will we ever make them more efficient? Probably. |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 15:58:27 +0100, whisky-dave wrote:
On Thursday, 3 October 2019 15:10:44 UTC+1, Commander Kinsey wrote: On Thu, 03 Oct 2019 14:58:46 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:45:38 UTC+1, Commander Kinsey wrote: On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just like why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance. Every conductor has resistance apart from perhaps a superconductor. yuo also have theb curent passing from one type of conductor to another. I assumed that the layers were so thin, resistance should be minimal. Depending on yuor refernce point for thin and minimal. Well they're measured in microns, not mm. I guess transistors are the same and they get hot. Semiconductors probably have quite a high resistance? Well yes compared to low or zero. I was thinking "enough to make them increase in temperature by many C". My domestic LED lamps get just over body temperature. That's 20C of heating. One of those conductors will convert the energy to light and heat. They won;t create much IR or UV because the material chosen was chosen because it emits the required wavelengh of light and not much eles. and if it can be overcome by using different materials. No they have been trying for years and until someone can come up with a magic substance that has zero resistance that is. Well they've certainly improved the efficiency over the years. The question is how far can they get without using them at absolute zero? Or perhaps even a completely different way of generating light? There's bio-luminescence and using a lattice structure like butterfly wings that could be used and have been used in high end modern displays. But bio-luminescence is diffiuclt to control at speed. We wouldn't need speed for room lighting. |
Why do LEDs generate heat?
That's different, that's asking for generating power from nothing. I just want something that changes electricity into light and nothing else. Or virtually nothing else, like 1% of it wasted. Current LEDs I'm told waste 60%.
On Thu, 03 Oct 2019 16:35:03 +0100, Brian Gaff wrote: One obviously has inefficiencies or the perpetual motion machine would be everywhere. Brian |
Why do LEDs generate heat?
On 03/10/2019 15:16, Commander Kinsey wrote:
On Thu, 03 Oct 2019 15:08:43 +0100, Martin Brown wrote: On 03/10/2019 14:45, Commander Kinsey wrote: On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey* wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just lioke why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance and if it can be overcome by using different materials.* And are you It is resistance in the sense that there is some frictional losses to the movement of current in the crystal lattice. Early LEDs you could bump up the quantum efficiency by stiffening it - immersing in LN2 worked a few times before thermal cycling killed it stone dead. sure it's even resistance?* It could be some photons are reabsorbed before they escape the LED, generating heat. White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. I didn't realise that, I thought white LEDs were designed to directly emit a handful of different visible light wavelengths to make white.* Is there a reason this can't be done?* An LED can make anything in the visible light spectrum, so surely a mixture of them would be more efficient than using phosphors?* There could even be seperate LEDs within the housing, like growlamps which have visible, IR, and UV LEDs. Tricolour can also be done but at the moment super efficient blue photon production and then down convert to yellow to get white is best. You can get tricolour high power LEDs that can be mixed to generate any colour in consumer grade and theatre grade lighting systems too. Magenta Growlights that only have blue and red LEDs are also now fairly common. No point in having any green since chlorophyll reflects it. -- Regards, Martin Brown |
Why do LEDs generate heat?
On 03/10/2019 15:16, Commander Kinsey wrote:
On Thu, 03 Oct 2019 15:08:43 +0100, Martin Brown wrote: White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. I didn't realise that, I thought white LEDs were designed to directly emit a handful of different visible light wavelengths to make white.* Is there a reason this can't be done?* An LED can make anything in the visible light spectrum, so surely a mixture of them would be more efficient than using phosphors?* There could even be seperate LEDs within the housing, like growlamps which have visible, IR, and UV LEDs. You can have red, green and blue LEDs to make up white, but it's less efficient and usually not worth doing unless you want to vary the hue. -- Max Demian |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 16:57:59 +0100, Martin Brown wrote:
On 03/10/2019 15:16, Commander Kinsey wrote: On Thu, 03 Oct 2019 15:08:43 +0100, Martin Brown wrote: On 03/10/2019 14:45, Commander Kinsey wrote: On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just lioke why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance and if it can be overcome by using different materials. And are you It is resistance in the sense that there is some frictional losses to the movement of current in the crystal lattice. Early LEDs you could bump up the quantum efficiency by stiffening it - immersing in LN2 worked a few times before thermal cycling killed it stone dead. sure it's even resistance? It could be some photons are reabsorbed before they escape the LED, generating heat. White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. I didn't realise that, I thought white LEDs were designed to directly emit a handful of different visible light wavelengths to make white. Is there a reason this can't be done? An LED can make anything in the visible light spectrum, so surely a mixture of them would be more efficient than using phosphors? There could even be seperate LEDs within the housing, like growlamps which have visible, IR, and UV LEDs. Tricolour can also be done but at the moment super efficient blue photon production and then down convert to yellow to get white is best. I see. You can get tricolour high power LEDs that can be mixed to generate any colour in consumer grade and theatre grade lighting systems too. Yes, Phillips make them ("hue"?). I don't know how efficient they are. Magenta Growlights that only have blue and red LEDs are also now fairly common. No point in having any green since chlorophyll reflects it. Yes I think there's no green in mine, it appears purple to look at it. Probably R, B, UV, and IR. I wasn't aware plants could use IR, but it said that on the instructions. I guess there's IR in sunlight so plants maybe make use of it. I wonder why they don't use green? Maybe creating black chlorophyll would be impossible. |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 17:03:55 +0100, Max Demian wrote:
On 03/10/2019 15:16, Commander Kinsey wrote: On Thu, 03 Oct 2019 15:08:43 +0100, Martin Brown wrote: White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. I didn't realise that, I thought white LEDs were designed to directly emit a handful of different visible light wavelengths to make white. Is there a reason this can't be done? An LED can make anything in the visible light spectrum, so surely a mixture of them would be more efficient than using phosphors? There could even be seperate LEDs within the housing, like growlamps which have visible, IR, and UV LEDs. You can have red, green and blue LEDs to make up white, but it's less efficient and usually not worth doing unless you want to vary the hue. I see. So for some reason blue LEDs are more efficient? (Even after wasting energy converting it with phosphors?) Do you know why? |
Why do LEDs generate heat?
On 03/10/2019 17:06, Commander Kinsey wrote:
On Thu, 03 Oct 2019 17:03:55 +0100, Max Demian wrote: On 03/10/2019 15:16, Commander Kinsey wrote: On Thu, 03 Oct 2019 15:08:43 +0100, Martin Brown wrote: White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. I didn't realise that, I thought white LEDs were designed to directly emit a handful of different visible light wavelengths to make white.* Is there a reason this can't be done?* An LED can make anything in the visible light spectrum, so surely a mixture of them would be more efficient than using phosphors?* There could even be seperate LEDs within the housing, like growlamps which have visible, IR, and UV LEDs. You can have red, green and blue LEDs to make up white, but it's less efficient and usually not worth doing unless you want to vary the hue. I see.* So for some reason blue LEDs are more efficient?* (Even after wasting energy converting it with phosphors?)* Do you know why? A guy got the Nobel prize for his contribution to making super efficient blue LEDs - mainly making the right substrate and getting it to work. https://www.bbc.co.uk/news/science-environment-29518521 A lot of others had tried for decades and failed dismally. There was a prehistoric dim blue LED based on silicon carbide used as indicators in a handful of expensive 1970's power amplifiers. They were very dim even by the dim standards of LEDs of that era, but blue. http://ledmuseum.net/ledsic.htm The odd one pops up from time to time as a novelty. -- Regards, Martin Brown |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 17:33:19 +0100, Martin Brown wrote:
On 03/10/2019 17:06, Commander Kinsey wrote: On Thu, 03 Oct 2019 17:03:55 +0100, Max Demian wrote: On 03/10/2019 15:16, Commander Kinsey wrote: On Thu, 03 Oct 2019 15:08:43 +0100, Martin Brown wrote: White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. I didn't realise that, I thought white LEDs were designed to directly emit a handful of different visible light wavelengths to make white. Is there a reason this can't be done? An LED can make anything in the visible light spectrum, so surely a mixture of them would be more efficient than using phosphors? There could even be seperate LEDs within the housing, like growlamps which have visible, IR, and UV LEDs. You can have red, green and blue LEDs to make up white, but it's less efficient and usually not worth doing unless you want to vary the hue. I see. So for some reason blue LEDs are more efficient? (Even after wasting energy converting it with phosphors?) Do you know why? A guy got the Nobel prize for his contribution to making super efficient blue LEDs - mainly making the right substrate and getting it to work. https://www.bbc.co.uk/news/science-environment-29518521 A lot of others had tried for decades and failed dismally. Perhaps one day there will be just as efficient LEDs of all colours and we can do away with the phosphor? There was a prehistoric dim blue LED based on silicon carbide used as indicators in a handful of expensive 1970's power amplifiers. They were very dim even by the dim standards of LEDs of that era, but blue. http://ledmuseum.net/ledsic.htm The odd one pops up from time to time as a novelty. |
Troll-feeding Senile ASSHOLE Alert!
On Thu, 3 Oct 2019 16:57:59 +0100, Martin Brownnoser, another mentally
challenged, troll-feeding senile idiot, blathered again: Magenta Growlights that only have blue and red LEDs are also now fairly common. No point in having any green since chlorophyll reflects it. Another brain dead senile idiot who doesn't get what's really going on here! tsk |
Troll-feeding Senile ASSHOLE Alert!
On Thu, 3 Oct 2019 17:03:55 +0100, Max Dumb, another mentally deficient
inveterate troll-feeding senile idiot, blathered again: You can have red, green and blue LEDs to make up white, but it's less efficient and usually not worth doing unless you want to vary the hue. ALL the sociopathic REALLY wants is that you feed him, any time he wants to be fed by some senile asshole, senile asshole! |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 17:42:16 +0100, Tim Streater wrote:
In article , Commander Kinsey wrote: that on the instructions. I guess there's IR in sunlight so plants maybe make use of it. IR: also known as 'heat'. Surely not required for the plants, as the room is heated by a greenhouse heater. Or do they insist on absorbing some through radiant energy? |
Why do LEDs generate heat?
Commander Kinsey wrote
Why do LEDs generate heat? Because not all the electricity used is turned into light. I want a technical answer not "because they're inefficient". And will we ever make them more efficient? Very likely with the higher powered leds. |
Why do LEDs generate heat?
"Commander Kinsey" wrote in message ... On Thu, 03 Oct 2019 14:37:34 +0100, whisky-dave wrote: On Thursday, 3 October 2019 14:29:30 UTC+1, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". That is the technical answer just lioke why does a wire get hot when curremnt passes through it. No, the technical answer would explain what part of it has resistance The diode that produces the light. and if it can be overcome by using different materials. There are no light emitting diodes which don't have resistance. And are you sure it's even resistance? Yes it is. And trivial to measure that. It could be some photons are reabsorbed before they escape the LED, generating heat. Nope. And will we ever make them more efficient? Probably. |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 18:20:05 +0100, Tim Streater wrote:
In article , Commander Kinsey wrote: On Thu, 03 Oct 2019 17:42:16 +0100, Tim Streater wrote: In article , Commander Kinsey wrote: that on the instructions. I guess there's IR in sunlight so plants maybe make use of it. IR: also known as 'heat'. Surely not required for the plants, as the room is heated by a greenhouse heater. Or do they insist on absorbing some through radiant energy? Go stand in the Sun and see if you absorb heat through radiant energy. I do, but I don't need it. We can be in a warm room and be comfortable without any radiant heat. Are plants not the same? |
Lonely Psychopathic Senile Ozzie Troll Alert!
On Fri, 4 Oct 2019 03:09:32 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again: I want a technical answer not "because they're inefficient". And will we ever make them more efficient? Very likely with the higher powered leds. You two idiots had better wonder whether they will ever find a cure for psychopathy and sociopathy which you deranged idiots keep exhibiting here! -- Website (from 2007) dedicated to the 85-year-old trolling senile cretin from Oz: https://www.pcreview.co.uk/threads/r...d-faq.2973853/ |
Why do LEDs generate heat?
On 03/10/2019 14:29, Commander Kinsey wrote:
Why do LEDs generate heat? I want a technical answer not "because they're inefficient". And will we ever make them more efficient? Besides the inefficiencies in the LED itself which other posters have covered, LED lamps have some current regulation or power supply built-in which will not be 100% efficient and thus generates heat. |
Why do LEDs generate heat?
"Commander Kinsey" wrote in message ... On Thu, 03 Oct 2019 17:33:19 +0100, Martin Brown wrote: On 03/10/2019 17:06, Commander Kinsey wrote: On Thu, 03 Oct 2019 17:03:55 +0100, Max Demian wrote: On 03/10/2019 15:16, Commander Kinsey wrote: On Thu, 03 Oct 2019 15:08:43 +0100, Martin Brown wrote: White LEDs rely on a yellow phosphor absorbing and re-emitting blue photons to make a perceived white light. Coloured LEDs typically have a forward voltage related to the energy of photon that they emit. There is a hit for doing that that limits ultimate efficiency to something like 40% of power consumed out as useful light. I didn't realise that, I thought white LEDs were designed to directly emit a handful of different visible light wavelengths to make white. Is there a reason this can't be done? An LED can make anything in the visible light spectrum, so surely a mixture of them would be more efficient than using phosphors? There could even be seperate LEDs within the housing, like growlamps which have visible, IR, and UV LEDs. You can have red, green and blue LEDs to make up white, but it's less efficient and usually not worth doing unless you want to vary the hue. I see. So for some reason blue LEDs are more efficient? (Even after wasting energy converting it with phosphors?) Do you know why? A guy got the Nobel prize for his contribution to making super efficient blue LEDs - mainly making the right substrate and getting it to work. https://www.bbc.co.uk/news/science-environment-29518521 A lot of others had tried for decades and failed dismally. Perhaps one day there will be just as efficient LEDs of all colours Unlikely given the physics involved. and we can do away with the phosphor? We already do and wear the lower efficiency. There was a prehistoric dim blue LED based on silicon carbide used as indicators in a handful of expensive 1970's power amplifiers. They were very dim even by the dim standards of LEDs of that era, but blue. http://ledmuseum.net/ledsic.htm The odd one pops up from time to time as a novelty. |
Why do LEDs generate heat?
On Thu, 03 Oct 2019 19:29:42 +0100, Robert wrote:
On 03/10/2019 14:29, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". And will we ever make them more efficient? Besides the inefficiencies in the LED itself which other posters have covered, LED lamps have some current regulation or power supply built-in which will not be 100% efficient and thus generates heat. True, but it's the LEDs themselves that are the warmest, and also the most susceptible to heat. |
Troll-feeding Senile IDIOT Alert!
On Thu, 03 Oct 2019 17:42:16 +0100, Dim Streater, the mentally handicapped,
notorious, troll-feeding, senile idiot, blathered again: IR: also known as 'heat'. Yep, Dim, YOU were still missing in the list of troll-feeding retarded senile idiots that regularly take the sociopathic Scottish ******'s baits! BG |
Troll-feeding Senile IDIOT Alert!
On Thu, 03 Oct 2019 18:20:05 +0100, Dim Streater, the mentally handicapped,
notorious, troll-feeding, senile idiot, blathered again: Go stand in the Sun and see if you absorb heat through radiant energy. Oh, no, not THAT retarded topic again, you two prize idiots! tsk |
Troll-feeding Senile ASSHOLE Alert!
On Thu, 3 Oct 2019 17:33:19 +0100, Martin Brownnoser, another troll-feeding,
senile idiot, blathered: There was a prehistoric dim blue LED based on silicon carbide used as indicators in a handful of expensive 1970's power amplifiers. They were very dim even by the dim standards of LEDs of that era, but blue. They couldn't possibly have been as dim as you two blithering idiots! |
Why do LEDs generate heat?
"Commander Kinsey" wrote in message
... On Thu, 03 Oct 2019 19:29:42 +0100, Robert wrote: On 03/10/2019 14:29, Commander Kinsey wrote: Why do LEDs generate heat? I want a technical answer not "because they're inefficient". And will we ever make them more efficient? Besides the inefficiencies in the LED itself which other posters have covered, LED lamps have some current regulation or power supply built-in which will not be 100% efficient and thus generates heat. True, but it's the LEDs themselves that are the warmest, and also the most susceptible to heat. But if you feel a Philips Hue bulb which is the size of an old tungsten 100W bulb, the part that gives off light (presumably where the LEDs are) is cool. It is the neck, near the fitting, which gets hot - and I presume that's where the PSU is. Likewise for GU10 bulbs (Philips Hue or ordinary non-dimmable LED) the front and conical sides don't get hot, whereas the neck near the fitting gets hot. |
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