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Why do LEDs generate heat?

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Mark Lloyd
Guest

Fri Oct 04, 2019 8:45 pm   



On 10/3/19 1:29 PM, Robert wrote:
Quote:
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.


I have a LED bulb (60W equivalent) in a lamp here. The bulb itself
doesn't get hot like an incandescent bulb does. What gets hot is an area
around the base.

--
82 days until the winter celebration (Wed, Dec 25, 2019 12:00:00 AM for
1 day).

Mark Lloyd
http://notstupid.us/

"You didn't hear it You didn't see it..." ...how absurd it all seems
without any proof" -- from "Tommy" by 'The Who'

Commander Kinsey
Guest

Fri Oct 04, 2019 9:45 pm   



On Fri, 04 Oct 2019 20:32:33 +0100, Mark Lloyd <not_at_mail.invalid> wrote:

Quote:
On 10/3/19 1:29 PM, 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.

I have a LED


That irritates me, why don't you write "an LED"? How do you say "LED"? I say "Ell Eee Dee", not "Light Emitting Diode". So it needs an "an", not an "a".

> bulb (60W equivalent) in a lamp here.

60W? Are you a Klingon and love darkness? I use 100W and 150W bulbs only. And lots of them. My living room (7 metres by 4 metres) contains 13 90W bulbs.

Quote:
The bulb itself
doesn't get hot like an incandescent bulb does. What gets hot is an area
around the base.


Through the heatsink probably, most of the heat is generated by the LEDs, not the far more efficient power supply.

NY
Guest

Sat Oct 05, 2019 8:45 pm   



"Commander Kinsey" <CFKinsey_at_military.org.jp> wrote in message
news:op.z87a1eyjwdg98l_at_picard.lan...
Quote:
On Sat, 05 Oct 2019 19:46:08 +0100, Mark Lloyd <not_at_mail.invalid> wrote:

On 10/4/19 2:51 PM, Commander Kinsey wrote:
bulb (60W equivalent) in a lamp here.

60W? Are you a Klingon and love darkness? I use 100W and 150W bulbs
only. And lots of them. My living room (7 metres by 4 metres) contains
13 90W bulbs.

It also matters if the light source is in the right place, like from
behind is good if you're reading or watching TV.

I prefer the whole room to be evenly lit.

Some people think more light is always better. I remember working behind
a TV (26-inch CRT console), where I could see OK. Then someone, trying
to be helpful, turned on a nearby wall lamp. The effect of that is that
the area behind the TV became completely BLACK.

More light is better if the whole room is lit evenly. Which is why I
prefer strip lights to point sources. Much better if you're soldering for
example, you don't create shadows, as light can come to the workpiece from
all angles, no matter where your body/head/hands/tools are.


Exactly. It is the use that you are making of the light which governs
whether you want a point source and directional lighting, or a diffuse
light.

I prefer to read with a light over my shoulder to light the pages of the
book, but with the rest of the room dark enough than I'm not distracted by
everything else around the book. Likewise for watching TV - screen brighter
than ambient light, even if the ambient light isn't reducing screen contrast
by brightening the dark parts of it.


My wife prefers uniform lighting - even if that means you are looking into
the light. When reading in bed, she will turn on the overhead light (single
ceiling rose or lots of GU10 spotlights) which illuminate the rest of the
room and shine right in your face, but leave the pages of the book in
shadow, She believes that reading by over-the-shoulder light, with the book
brighter than the background, strains your eyes.

NY
Guest

Sat Oct 05, 2019 8:45 pm   



"Mark Lloyd" <not_at_mail.invalid> wrote in message
news:Rx5mF.17840$JD1.8167_at_fx11.iad...
Quote:
On 10/4/19 2:51 PM, Commander Kinsey wrote:

I have a LED

That irritates me, why don't you write "an LED"? How do you say "LED"?
I say "Ell Eee Dee", not "Light Emitting Diode". So it needs an "an",
not an "a".

"an LED" irritates me. I know the word is "light".


I think it is normal convention that an initialism that starts with a *vowel
sound* takes "an", on the grounds of euphony: that in normal English, you
never precede a word that starts with a vowel sound with "a".

Hence an apple, but a uniform. A hedge or a hotel or a historic event but an
honourable occasion (H is sounded for the first three but silent for the
last one). For some reason, it considered "better" to use "an" before hotel
and historic, even though the H is sounded. That sounds as daft to my ears
as "an spoon" - it's not a vowel sound so you use "a". I could understand if
people pronounce hotel the French way, but it needs to be consistent: "an
'otel" or "a hotel".


As regards initialisms/abbreviations, you do get anomalies like "an LED"
(ell-ee-dee) that starts with a consonant but "a UFO" (you-eff-oh) that
starts with a vowel pronounced as a consonant.

Peeler
Guest

Sat Oct 05, 2019 8:45 pm   



On Sat, 5 Oct 2019 13:46:08 -0500, Mark Lloyd, another absolutely brain
dead, troll-feeding, senile cretin, drivelled:

Quote:

"an LED" irritates me. I know the word is "light".


You must about as big an idiot as the retarded troll you keep feeding,
senile cretin! LOL

Commander Kinsey
Guest

Sat Oct 05, 2019 8:45 pm   



On Sat, 05 Oct 2019 19:46:08 +0100, Mark Lloyd <not_at_mail.invalid> wrote:

Quote:
On 10/4/19 2:51 PM, Commander Kinsey wrote:

[snip]

I have a LED

That irritates me, why don't you write "an LED"? How do you say "LED"?
I say "Ell Eee Dee", not "Light Emitting Diode". So it needs an "an",
not an "a".

"an LED" irritates me. I know the word is "light".


But which would you say if you read the sentence out loud? Do you say the letters like me, or do you say the full words? I say "DVLA" not "Driver and Vehicle Licensing Authority"

Quote:
bulb (60W equivalent) in a lamp here.

60W? Are you a Klingon and love darkness? I use 100W and 150W bulbs
only. And lots of them. My living room (7 metres by 4 metres) contains
13 90W bulbs.

It also matters if the light source is in the right place, like from
behind is good if you're reading or watching TV.


I prefer the whole room to be evenly lit.

Quote:
Some people think more light is always better. I remember working behind
a TV (26-inch CRT console), where I could see OK. Then someone, trying
to be helpful, turned on a nearby wall lamp. The effect of that is that
the area behind the TV became completely BLACK.


More light is better if the whole room is lit evenly. Which is why I prefer strip lights to point sources. Much better if you're soldering for example, you don't create shadows, as light can come to the workpiece from all angles, no matter where your body/head/hands/tools are.

Mark Lloyd
Guest

Sat Oct 05, 2019 8:45 pm   



On 10/4/19 2:51 PM, Commander Kinsey wrote:

[snip]

Quote:
I have a LED

That irritates me, why don't you write "an LED"?  How do you say "LED"?
I say "Ell Eee Dee", not "Light Emitting Diode".  So it needs an "an",
not an "a".


"an LED" irritates me. I know the word is "light".

Quote:
bulb (60W equivalent) in a lamp here.

60W?  Are you a Klingon and love darkness?  I use 100W and 150W bulbs
only.  And lots of them.  My living room (7 metres by 4 metres) contains
13 90W bulbs.


It also matters if the light source is in the right place, like from
behind is good if you're reading or watching TV.

Some people think more light is always better. I remember working behind
a TV (26-inch CRT console), where I could see OK. Then someone, trying
to be helpful, turned on a nearby wall lamp. The effect of that is that
the area behind the TV became completely BLACK.

[snip]

--
81 days until the winter celebration (Wed, Dec 25, 2019 12:00:00 AM for
1 day).

Mark Lloyd
http://notstupid.us/

"Tinnitus is a pain in the neck"

Peeler
Guest

Sat Oct 05, 2019 9:45 pm   



On Sat, 5 Oct 2019 20:33:14 +0100, NY, the notorious, troll-feeding,
endlessly blathering senile idiot, blathered again:



> My wife prefers uniform lighting

You got a "wife", troll-feeding senile idiot? Does she know about you
sucking troll cock on Usenet on every occasion? <BG>

Commander Kinsey
Guest

Sat Oct 05, 2019 9:45 pm   



On Sat, 05 Oct 2019 20:23:02 +0100, NY <me_at_privacy.invalid> wrote:

Quote:
"Mark Lloyd" <not_at_mail.invalid> wrote in message
news:Rx5mF.17840$JD1.8167_at_fx11.iad...
On 10/4/19 2:51 PM, Commander Kinsey wrote:

I have a LED

That irritates me, why don't you write "an LED"? How do you say "LED"?
I say "Ell Eee Dee", not "Light Emitting Diode". So it needs an "an",
not an "a".

"an LED" irritates me. I know the word is "light".

I think it is normal convention that an initialism that starts with a *vowel
sound* takes "an", on the grounds of euphony: that in normal English, you
never precede a word that starts with a vowel sound with "a".

Hence an apple, but a uniform. A hedge or a hotel or a historic event but an
honourable occasion (H is sounded for the first three but silent for the
last one). For some reason, it considered "better" to use "an" before hotel
and historic, even though the H is sounded. That sounds as daft to my ears
as "an spoon" - it's not a vowel sound so you use "a". I could understand if
people pronounce hotel the French way, but it needs to be consistent: "an
'otel" or "a hotel".


My god! I agree with you completely. I was about to say the same thing as soon as you wrote "a historic event", it's really grating to my ears to hear an historic.

Also, Americans get the Hs wrong. Like erb, as in marijuana. An 'erb would be fine, but they think the H is always silent.

Quote:
As regards initialisms/abbreviations, you do get anomalies like "an LED"
(ell-ee-dee) that starts with a consonant but "a UFO" (you-eff-oh) that
starts with a vowel pronounced as a consonant.


I say "a URL" for a web address, but I knew someone who said "an url", as in how you would pronounce "hurl" with a silent H. He insisted that acronyms should be pronounced like words. WLED became "well-ed", as in "well" followed by the name "Ed". I assume because pronouncing a W before an L was too difficult, so he then added extra vowels.

Commander Kinsey
Guest

Sat Oct 05, 2019 9:45 pm   



On Sat, 05 Oct 2019 20:33:14 +0100, NY <me_at_privacy.invalid> wrote:

Quote:
"Commander Kinsey" <CFKinsey_at_military.org.jp> wrote in message
news:op.z87a1eyjwdg98l_at_picard.lan...
On Sat, 05 Oct 2019 19:46:08 +0100, Mark Lloyd <not_at_mail.invalid> wrote:

On 10/4/19 2:51 PM, Commander Kinsey wrote:
bulb (60W equivalent) in a lamp here.

60W? Are you a Klingon and love darkness? I use 100W and 150W bulbs
only. And lots of them. My living room (7 metres by 4 metres) contains
13 90W bulbs.

It also matters if the light source is in the right place, like from
behind is good if you're reading or watching TV.

I prefer the whole room to be evenly lit.

Some people think more light is always better. I remember working behind
a TV (26-inch CRT console), where I could see OK. Then someone, trying
to be helpful, turned on a nearby wall lamp. The effect of that is that
the area behind the TV became completely BLACK.

More light is better if the whole room is lit evenly. Which is why I
prefer strip lights to point sources. Much better if you're soldering for
example, you don't create shadows, as light can come to the workpiece from
all angles, no matter where your body/head/hands/tools are.


Exactly. It is the use that you are making of the light which governs
whether you want a point source and directional lighting, or a diffuse
light.

I prefer to read with a light over my shoulder to light the pages of the
book, but with the rest of the room dark enough than I'm not distracted by
everything else around the book. Likewise for watching TV - screen brighter
than ambient light, even if the ambient light isn't reducing screen contrast
by brightening the dark parts of it.


I always like everything lit in the room, or I doze off.

Quote:
My wife prefers uniform lighting - even if that means you are looking into
the light. When reading in bed, she will turn on the overhead light (single
ceiling rose or lots of GU10 spotlights) which illuminate the rest of the
room and shine right in your face, but leave the pages of the book in
shadow, She believes that reading by over-the-shoulder light, with the book
brighter than the background, strains your eyes.


That may be true, and why I feel sleepy if I do so. But then some people read to get to sleep.

%
Guest

Sat Oct 05, 2019 9:45 pm   



On 2019-10-05 12:48 p.m., Commander Kinsey wrote:
Quote:
On Sat, 05 Oct 2019 20:33:14 +0100, NY <me_at_privacy.invalid> wrote:

"Commander Kinsey" <CFKinsey_at_military.org.jp> wrote in message
news:op.z87a1eyjwdg98l_at_picard.lan...
On Sat, 05 Oct 2019 19:46:08 +0100, Mark Lloyd <not_at_mail.invalid> wrote:

On 10/4/19 2:51 PM, Commander Kinsey wrote:
bulb (60W equivalent) in a lamp here.

60W?  Are you a Klingon and love darkness?  I use 100W and 150W bulbs
only.  And lots of them.  My living room (7 metres by 4 metres)
contains
13 90W bulbs.

It also matters if the light source is in the right place, like from
behind is good if you're reading or watching TV.

I prefer the whole room to be evenly lit.

Some people think more light is always better. I remember working
behind
a TV (26-inch CRT console), where I could see OK. Then someone, trying
to be helpful, turned on a nearby wall lamp. The effect of that is that
the area behind the TV became completely BLACK.

More light is better if the whole room is lit evenly.  Which is why I
prefer strip lights to point sources.  Much better if you're
soldering for
example, you don't create shadows, as light can come to the workpiece
from
all angles, no matter where your body/head/hands/tools are.


Exactly. It is the use that you are making of the light which governs
whether you want a point source and directional lighting, or a diffuse
light.

I prefer to read with a light over my shoulder to light the pages of the
book, but with the rest of the room dark enough than I'm not
distracted by
everything else around the book. Likewise for watching TV - screen
brighter
than ambient light, even if the ambient light isn't reducing screen
contrast
by brightening the dark parts of it.

I always like everything lit in the room, or I doze off.

My wife prefers uniform lighting - even if that means you are looking
into
the light. When reading in bed, she will turn on the overhead light
(single
ceiling rose or lots of GU10 spotlights) which illuminate the rest of the
room and shine right in your face, but leave the pages of the book in
shadow, She believes that reading by over-the-shoulder light, with the
book
brighter than the background, strains your eyes.

That may be true, and why I feel sleepy if I do so.  But then some
people read to get to sleep.


i have sex to fall asleep and i don't care what the lights are doing

Max Demian
Guest

Sat Oct 05, 2019 11:45 pm   



On 05/10/2019 19:46, Mark Lloyd wrote:
Quote:
On 10/4/19 2:51 PM, Commander Kinsey wrote:

[snip]

I have a LED

That irritates me, why don't you write "an LED"?  How do you say
"LED"? I say "Ell Eee Dee", not "Light Emitting Diode".  So it needs
an "an", not an "a".

"an LED" irritates me. I know the word is "light".


It's "a LED" if you pronounce it as an acronym.

--
Max Demian

Commander Kinsey
Guest

Sun Oct 06, 2019 12:45 am   



On Sat, 05 Oct 2019 23:08:43 +0100, Max Demian <max_demian_at_bigfoot.com> wrote:

Quote:
On 05/10/2019 19:46, Mark Lloyd wrote:
On 10/4/19 2:51 PM, Commander Kinsey wrote:

[snip]

I have a LED

That irritates me, why don't you write "an LED"? How do you say
"LED"? I say "Ell Eee Dee", not "Light Emitting Diode". So it needs
an "an", not an "a".

"an LED" irritates me. I know the word is "light".

It's "a LED" if you pronounce it as an acronym.


What do you mean by "pronounce it as an acronym"? I would have said that means "ell eee dee" as in you're treating it as an acronym rather than a word and spelling it out.

Max Demian
Guest

Sun Oct 06, 2019 10:45 am   



On 06/10/2019 00:14, Commander Kinsey wrote:
Quote:
On Sat, 05 Oct 2019 23:08:43 +0100, Max Demian <max_demian_at_bigfoot.com
wrote:

On 05/10/2019 19:46, Mark Lloyd wrote:
On 10/4/19 2:51 PM, Commander Kinsey wrote:

[snip]

I have a LED

That irritates me, why don't you write "an LED"?  How do you say
"LED"? I say "Ell Eee Dee", not "Light Emitting Diode".  So it needs
an "an", not an "a".

"an LED" irritates me. I know the word is "light".

It's "a LED" if you pronounce it as an acronym.

What do you mean by "pronounce it as an acronym"?  I would have said
that means "ell eee dee" as in you're treating it as an acronym rather
than a word and spelling it out.


An acronym is a pronounceable abbreviation, e.g. NATO, scuba, radar.

--
Max Demian

Peeler
Guest

Sun Oct 06, 2019 11:45 am   



On Sun, 6 Oct 2019 10:07:15 +0100, Max Dumb, another mentally deficient
inveterate troll-feeding senile idiot, blathered again:


Quote:
What do you mean by "pronounce it as an acronym"?  I would have said
that means "ell eee dee" as in you're treating it as an acronym rather
than a word and spelling it out.

An acronym is a pronounceable abbreviation, e.g. NATO, scuba, radar.


LOL Oh, no, another bullshit "conversation" ensuing!

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