LED Bulb Efficiency vs. Operating Life

In article <tqbo3l$1rk6$1@gioia.aioe.org>,
Martin Brown  <'''newspam'''@nonad.co.uk> wrote:
>On 19/01/2023 15:11, albert wrote:
>> In article <nnd$4d9a769b$61464ae6@e846562bf142425e>,
>> Sjouke Burry  <burrynulnulfour@ppllaanneett.nnll> wrote:
>>> On 26.12.22 18:16, Ricky wrote:
>>>> I know it costs more to make a more efficient LED bulb for room
>>> lighting.  Is there also a tradeoff between efficiency and operating
>>> life?  I can't think of a mechanism, but I'm not so familiar with LED
>>> light bulb design.
>>>>
>>> Lots of light, high chip temp, shorter chip life.
>>
>> This can be offset by operating the leds vastly below capacity.
>> E.g. I have a flash light costing 3.5 euro with 37 leds.
>> I estimate that the leds have an effectively infinite life span.
>> Unlike light bulbs you can diminish the current and have approximately
>> proportional light.
>
>The catch is that if they are all in series with a current source or
>worse rectified mains then the first one to fail takes the entire chain
>out so MTBF is about 1/N th of the N components in the chain. I have
>seen some where there were ~60 white leds in series.

That is true in mains application. A pocket light working from
3 AA's have the leds in parallel. There is a series resistor,
possibly to a group of leds.
A single led failing has no consequences.
The failure modes are dropping from two meters on a concrete flour,
and the switch.

>
>Traffic lights seem to have about 4 chains that are independent so you
>don't get nice even illumination if one fails but they don't just stop
>completely one day like the old filament bulbs did.
>
>--
>Regards,
>Martin Brown
>
-- 
Don't praise the day before the evening. One swallow doesn't make spring.
You must not say "hey" before you have crossed the bridge. Don't sell the
hide of the bear until you shot it. Better one bird in the hand than ten in
the air. First gain is a cat spinning.            - the Wise from Antrim -

On Fri, 20 Jan 2023 09:03:29 +0000, Martin Brown
<'''newspam'''@nonad.co.uk> wrote:

>On 20/01/2023 00:58, Ricky wrote:
>> On Thursday, January 19, 2023 at 5:31:57 PM UTC-5, bitrex wrote:
>>> On 1/19/2023 5:20 PM, Ricky wrote:
>>>> On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex wrote:
>>>>> On 12/27/2022 11:39 AM, John Larkin wrote:
>>>>>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown 
>>>>>> <'''newspam'''@nonad.co.uk> wrote:
>>>>>> 
>>>>>>> On 26/12/2022 17:16, Ricky wrote:
>>>>>>>> I know it costs more to make a more efficient LED bulb
>>>>>>>> for room lighting. Is there also a tradeoff between
>>>>>>>> efficiency and operating life? I can't think of a
>>>>>>>> mechanism, but I'm not so familiar with LED light bulb
>>>>>>>> design.
>>>>>>> 
>>>>>>> If you push the blue light flux and/or residual heating
>>>>>>> high enough it can damage/darken the phosphor used to
>>>>>>> generate the yellow light.
>>>>>>> 
>>>>>>> The surface brightness of recent LEDs is now about the same
>>>>>>> per unit area as the sun - which makes it a bad idea to
>>>>>>> look directly at them. Blue, violet or UV ones especially.
>>>>>> 
>>>>>> I have a 12-volt, roughly 1 cm square, array that looks like
>>>>>> a welding torch. It's the kind used in street lamps.
>>>>>> 
>>>>>> Why don't they diffuse LED street lamps? They are annoying.
>>>>>> 
>>>>> Especially when they start blinking
>>>> 
>>>> I can't stand the fast blinking LED tail lights on cars.
>>>> Everytime I move my line of view, they create a dozen spots of
>>>> light. When there are more than one it gets insane looking. Seems
>>>> like most people don't even see this. The first time it happened
>>>> to me I was trying to merge where there was no merge lane and the
>>>> ramp was coming from an angle, rather than merging while driving
>>>> parallel, so the rear view mirror didn't show anything useful. A
>>>> quick look over my shoulder showed one car passing me, just as I
>>>> needed to either go or stop. As I turned my head back, the tail
>>>> lights (those tall Cadillac tail lights) suddenly blossomed into
>>>> a dozen pairs of lights and I thought it was a bunch of cars! I
>>>> had to hit my brakes to avoid an accident, only to find there was
>>>> only the one car. Insane that they would create this sort of
>>>> hazard, even if everyone doesn't see it. It's the sort of thing
>>>> that would be changed on an airliner, after the first accident it
>>>> causes.
>>>> 
>>>> I've never found out how rapid the blinking is.
>>>> 
>>> I usually see those flashing brake light mods on street racer-type
>>> cars around Providence RI, kids put them on their old Eclipse etc.
>>> to make them look cool. I don't know that they're much improvement
>>> over a regular high-level lamp at avoiding being rear-ended,
>>> though.
>> 
>> We aren't talking about the same thing.  I'm talking about tail/brake
>> lights where the brightness is adjusted by PWM.  It saves a few cents
>> by leaving off the inductor too smooth the waveform into a level.
>
>The problem is that they PWM pulse them at a frequency that some people 
>can see in their peripheral vision (which is much more flicker 
>sensitive). I guess the engineers who designed it didn't think about 
>their choice of frequency too hard. Anything above about 300HZ frequency 
>would look pretty much continuous but there seem to be several car 
>makers (and street furniture makers that use ~100Hz at a guess).
>
>People who see this as a problem are the same ones who don't get on with 
>walls full of TVs or large screen monitors at 60Hz refresh rates.

It would be fun to connect a photodetector to an amp and headphones
and listen to the light in our world, indoors and out. I might do
that.

I did that that with a coil and mag fields when I was a kid. It would
be different now.

On Monday, December 26, 2022 at 4:01:16 PM UTC-5, John Larkin wrote:
> On Mon, 26 Dec 2022 19:49:05 +0100, Sjouke Burry 
> <burrynu...@ppllaanneett.nnll> wrote: 
> 
> >On 26.12.22 18:16, Ricky wrote: 
> >> I know it costs more to make a more efficient LED bulb for room lighting. Is there also a tradeoff between efficiency and operating life? I can't think of a mechanism, but I'm not so familiar with LED light bulb design. 
> >> 
> >Lots of light, high chip temp, shorter chip life.
> LED efficiency drops radically at high currents and high temps, and 
> LEDs degrade ditto. There is no tradeoff of efficiency vs reliability. 
> The real tradeoff is light vs cost. 
> 
> For fun, blast an LED with freeze spray.

Right, it's just another pseudo-electronics pest question.

Once the manufacturer has settled on a particular market, there's not a whole lot of wiggle room. The market has everything to do with performance characteristics of the final product, and that includes operating life. 

Unbelievably unfocused article on the subject:

https://www.edn.com/lighting-industry-standards/

On 1/19/2023 7:58 PM, Ricky wrote:

>>> I can't stand the fast blinking LED tail lights on cars. Everytime I move my line of view, they create a dozen spots of light. When there are more than one it gets insane looking. Seems like most people don't even see this. The first time it happened to me I was trying to merge where there was no merge lane and the ramp was coming from an angle, rather than merging while driving parallel, so the rear view mirror didn't show anything useful. A quick look over my shoulder showed one car passing me, just as I needed to either go or stop. As I turned my head back, the tail lights (those tall Cadillac tail lights) suddenly blossomed into a dozen pairs of lights and I thought it was a bunch of cars! I had to hit my brakes to avoid an accident, only to find there was only the one car. Insane that they would create this sort of hazard, even if everyone doesn't see it. It's the sort of thing that would be changed on an airliner, after the first accident it causes.
>>>
>>> I've never found out how rapid the blinking is.
>>>
>> I usually see those flashing brake light mods on street racer-type cars
>> around Providence RI, kids put them on their old Eclipse etc. to make
>> them look cool. I don't know that they're much improvement over a
>> regular high-level lamp at avoiding being rear-ended, though.
> 
> We aren't talking about the same thing.  I'm talking about tail/brake lights where the brightness is adjusted by PWM.  It saves a few cents by leaving off the inductor too smooth the waveform into a level.
> 

Right, I guess they don't bother me the same way. I'll if I notice any 
flicker more often in my peripheral vision now that you mention it.

albert <albert@cherry.(none)> wrote:

[...]
> The failure modes are dropping from two meters on a concrete flour,
> and the switch.

...and leaking batteries.


-- 
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

On 1/20/2023 11:00 AM, John Larkin wrote:
> On Fri, 20 Jan 2023 09:03:29 +0000, Martin Brown
> <'''newspam'''@nonad.co.uk> wrote:
> 
>> On 20/01/2023 00:58, Ricky wrote:
>>> On Thursday, January 19, 2023 at 5:31:57 PM UTC-5, bitrex wrote:
>>>> On 1/19/2023 5:20 PM, Ricky wrote:
>>>>> On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex wrote:
>>>>>> On 12/27/2022 11:39 AM, John Larkin wrote:
>>>>>>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown
>>>>>>> <'''newspam'''@nonad.co.uk> wrote:
>>>>>>>
>>>>>>>> On 26/12/2022 17:16, Ricky wrote:
>>>>>>>>> I know it costs more to make a more efficient LED bulb
>>>>>>>>> for room lighting. Is there also a tradeoff between
>>>>>>>>> efficiency and operating life? I can't think of a
>>>>>>>>> mechanism, but I'm not so familiar with LED light bulb
>>>>>>>>> design.
>>>>>>>>
>>>>>>>> If you push the blue light flux and/or residual heating
>>>>>>>> high enough it can damage/darken the phosphor used to
>>>>>>>> generate the yellow light.
>>>>>>>>
>>>>>>>> The surface brightness of recent LEDs is now about the same
>>>>>>>> per unit area as the sun - which makes it a bad idea to
>>>>>>>> look directly at them. Blue, violet or UV ones especially.
>>>>>>>
>>>>>>> I have a 12-volt, roughly 1 cm square, array that looks like
>>>>>>> a welding torch. It's the kind used in street lamps.
>>>>>>>
>>>>>>> Why don't they diffuse LED street lamps? They are annoying.
>>>>>>>
>>>>>> Especially when they start blinking
>>>>>
>>>>> I can't stand the fast blinking LED tail lights on cars.
>>>>> Everytime I move my line of view, they create a dozen spots of
>>>>> light. When there are more than one it gets insane looking. Seems
>>>>> like most people don't even see this. The first time it happened
>>>>> to me I was trying to merge where there was no merge lane and the
>>>>> ramp was coming from an angle, rather than merging while driving
>>>>> parallel, so the rear view mirror didn't show anything useful. A
>>>>> quick look over my shoulder showed one car passing me, just as I
>>>>> needed to either go or stop. As I turned my head back, the tail
>>>>> lights (those tall Cadillac tail lights) suddenly blossomed into
>>>>> a dozen pairs of lights and I thought it was a bunch of cars! I
>>>>> had to hit my brakes to avoid an accident, only to find there was
>>>>> only the one car. Insane that they would create this sort of
>>>>> hazard, even if everyone doesn't see it. It's the sort of thing
>>>>> that would be changed on an airliner, after the first accident it
>>>>> causes.
>>>>>
>>>>> I've never found out how rapid the blinking is.
>>>>>
>>>> I usually see those flashing brake light mods on street racer-type
>>>> cars around Providence RI, kids put them on their old Eclipse etc.
>>>> to make them look cool. I don't know that they're much improvement
>>>> over a regular high-level lamp at avoiding being rear-ended,
>>>> though.
>>>
>>> We aren't talking about the same thing.  I'm talking about tail/brake
>>> lights where the brightness is adjusted by PWM.  It saves a few cents
>>> by leaving off the inductor too smooth the waveform into a level.
>>
>> The problem is that they PWM pulse them at a frequency that some people
>> can see in their peripheral vision (which is much more flicker
>> sensitive). I guess the engineers who designed it didn't think about
>> their choice of frequency too hard. Anything above about 300HZ frequency
>> would look pretty much continuous but there seem to be several car
>> makers (and street furniture makers that use ~100Hz at a guess).
>>
>> People who see this as a problem are the same ones who don't get on with
>> walls full of TVs or large screen monitors at 60Hz refresh rates.
> 
> It would be fun to connect a photodetector to an amp and headphones
> and listen to the light in our world, indoors and out. I might do
> that.
> 
> I did that that with a coil and mag fields when I was a kid. It would
> be different now.
> 

It'll maybe need to be an amp with a logarithmic gain if you're going to 
use it both indoors and out, the dynamic range between lighting in an 
average office and out doors at noontime on a sunny day is like 90 dB.

On 20/01/2023 16:00, John Larkin wrote:

<snip>
> 
> It would be fun to connect a photodetector to an amp and headphones
> and listen to the light in our world, indoors and out. I might do
> that.

The visible spectrum covers about an octave, so translate the light 
frequencies into audio frequencies.

(Not sure how you'd do that.)

-- 
Cheers
Clive

On Friday, January 20, 2023 at 11:00:24 AM UTC-5, John Larkin wrote:
> On Fri, 20 Jan 2023 09:03:29 +0000, Martin Brown
> <'''newspam'''@nonad.co.uk> wrote: 
> 
> >On 20/01/2023 00:58, Ricky wrote: 
> >> On Thursday, January 19, 2023 at 5:31:57 PM UTC-5, bitrex wrote: 
> >>> On 1/19/2023 5:20 PM, Ricky wrote: 
> >>>> On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex wrote: 
> >>>>> On 12/27/2022 11:39 AM, John Larkin wrote: 
> >>>>>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown 
> >>>>>> <'''newspam'''@nonad.co.uk> wrote: 
> >>>>>> 
> >>>>>>> On 26/12/2022 17:16, Ricky wrote: 
> >>>>>>>> I know it costs more to make a more efficient LED bulb 
> >>>>>>>> for room lighting. Is there also a tradeoff between 
> >>>>>>>> efficiency and operating life? I can't think of a 
> >>>>>>>> mechanism, but I'm not so familiar with LED light bulb 
> >>>>>>>> design. 
> >>>>>>> 
> >>>>>>> If you push the blue light flux and/or residual heating 
> >>>>>>> high enough it can damage/darken the phosphor used to 
> >>>>>>> generate the yellow light. 
> >>>>>>> 
> >>>>>>> The surface brightness of recent LEDs is now about the same 
> >>>>>>> per unit area as the sun - which makes it a bad idea to 
> >>>>>>> look directly at them. Blue, violet or UV ones especially. 
> >>>>>> 
> >>>>>> I have a 12-volt, roughly 1 cm square, array that looks like 
> >>>>>> a welding torch. It's the kind used in street lamps. 
> >>>>>> 
> >>>>>> Why don't they diffuse LED street lamps? They are annoying. 
> >>>>>> 
> >>>>> Especially when they start blinking 
> >>>> 
> >>>> I can't stand the fast blinking LED tail lights on cars. 
> >>>> Everytime I move my line of view, they create a dozen spots of 
> >>>> light. When there are more than one it gets insane looking. Seems 
> >>>> like most people don't even see this. The first time it happened 
> >>>> to me I was trying to merge where there was no merge lane and the 
> >>>> ramp was coming from an angle, rather than merging while driving 
> >>>> parallel, so the rear view mirror didn't show anything useful. A 
> >>>> quick look over my shoulder showed one car passing me, just as I 
> >>>> needed to either go or stop. As I turned my head back, the tail 
> >>>> lights (those tall Cadillac tail lights) suddenly blossomed into 
> >>>> a dozen pairs of lights and I thought it was a bunch of cars! I 
> >>>> had to hit my brakes to avoid an accident, only to find there was 
> >>>> only the one car. Insane that they would create this sort of 
> >>>> hazard, even if everyone doesn't see it. It's the sort of thing 
> >>>> that would be changed on an airliner, after the first accident it 
> >>>> causes. 
> >>>> 
> >>>> I've never found out how rapid the blinking is. 
> >>>> 
> >>> I usually see those flashing brake light mods on street racer-type 
> >>> cars around Providence RI, kids put them on their old Eclipse etc. 
> >>> to make them look cool. I don't know that they're much improvement 
> >>> over a regular high-level lamp at avoiding being rear-ended, 
> >>> though. 
> >> 
> >> We aren't talking about the same thing. I'm talking about tail/brake 
> >> lights where the brightness is adjusted by PWM. It saves a few cents 
> >> by leaving off the inductor too smooth the waveform into a level. 
> > 
> >The problem is that they PWM pulse them at a frequency that some people 
> >can see in their peripheral vision (which is much more flicker 
> >sensitive). I guess the engineers who designed it didn't think about 
> >their choice of frequency too hard. Anything above about 300HZ frequency 
> >would look pretty much continuous but there seem to be several car 
> >makers (and street furniture makers that use ~100Hz at a guess). 
> > 
> >People who see this as a problem are the same ones who don't get on with 
> >walls full of TVs or large screen monitors at 60Hz refresh rates.
> It would be fun to connect a photodetector to an amp and headphones 
> and listen to the light in our world, indoors and out. I might do 
> that. 
> 
> I did that that with a coil and mag fields when I was a kid. It would 
> be different now.

I used a solar cell taped to the face of an oscilloscope to demodulate an AM radio signal in high school.  I did this because I realized, with a slow scan rate, the brightness would be related to the area the signal occupied on the screen, meaning the amplitude of the signal.  It worked!  But my electronics instructor thought it had to be the solar cell acting as a diode that was demodulating the waveform.  I later realized he had no idea what was going on with that circuit. 

-- 

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

On Friday, January 20, 2023 at 11:57:20 AM UTC-5, Clive Arthur wrote:
> On 20/01/2023 16:00, John Larkin wrote: 
> 
> <snip>
> > 
> > It would be fun to connect a photodetector to an amp and headphones 
> > and listen to the light in our world, indoors and out. I might do 
> > that.
> The visible spectrum covers about an octave, so translate the light 
> frequencies into audio frequencies. 
> 
> (Not sure how you'd do that.) 

Don't think it could be a direct conversion, but using three photodectors like the eye does, you can get an idea of the color and select a frequency to play based on that.  

I knew someone with a cochlear implant.  She knew a bit about how it worked.  I think she said it had only 16 electrodes, yet she could hear music well enough to enjoy it.  That impressed me.  Imagine how different it could be with 256 electrodes.  Music is such a rich medium!  

-- 

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

On 2023-01-20 17:34, bitrex wrote:
> On 1/20/2023 11:00 AM, John Larkin wrote:
>>
>> It would be fun to connect a photodetector to an amp and headphones
>> and listen to the light in our world, indoors and out. I might do
>> that.
>>
>> I did that that with a coil and mag fields when I was a kid. It would
>> be different now.
>>
> 
> It'll maybe need to be an amp with a logarithmic gain if you're going to use it both indoors and out, the dynamic range between lighting in an average office and out doors at noontime on a sunny day is like 90 dB.

Just use a photo diode, without parallel resistor, and AC-couple it to an amplifier.
The logarithmic response is provided by the forward biased diode itself.
E.g. 10% modulation, at whatever light intensity, will provide the same AC voltage.

Arie