LED Bulb Efficiency vs. Operating Life...

[panteltje]

On a sunny day (Fri, 20 Jan 2023 12:27:54 +0000) it happened Clive Arthur
<clive@nowaytoday.co.uk> wrote in <tqe1cb$22781$1@dont-email.me>:

On 20/01/2023 10:49, panteltje wrote:

snip

I have used the effect many times to its advantage:
http://panteltje.com/panteltje/pic/sign_pic/

and here:
http://panteltje.com/panteltje/quadcopter/hsign.html

The eye and both a camera with sufficient long exposure seem to be able to see the dots.
my Sony superhad video smeared it out though (second link)
They should really run the lights with DC.


I made one of those, also on Veroboard, though mine had 16 red LEDs. I
had the idea of mounting it on a rear windscreen wiper to send polite
and friendly messages to the car behind. Then I got a proper job.

You could use these in the rear window:
http://panteltje.com/panteltje/raspberry_pi_FDS132_matrix_display_driver/index.html

 

[none]

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 -

 

[John Larkin]

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.

 

[Fred Bloggs]

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/

 

[bitrex]

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.

 

[Liz Tuddenham]

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

 

[bitrex]

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.

 

[Clive Arthur]

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

 

[Ricky]

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

 

[Ricky]

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

 

[Arie de Muijnck]

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

 

[Arie de Muijnck]

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

 

[John Larkin]

On Fri, 20 Jan 2023 11:34:46 -0500, bitrex <user@example.net> wrote:

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.

We\'s only want to hear the AC component of modulated lights. A bit of
optics, even a cardboard tube, would allow aiming and help reject
ambient DC light.

Gain is cheap.

 

[server]

On Thu, 19 Jan 2023 16:11:35 +0100, albert@cherry.(none) (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.

Groetjes Albert

The problem with \'white\' LEDs is the degradation of the phosphor with
high currents. Running the LED at Imax and the light output will drop
significantly after a few hundred or a thousand hours. Running at
Imax/2 or even Imax/3 and the light output may be strong after claimed
30000 hours. The efficiency (in lm/W) is also better for the lower
current.

Reputable LED manufacturers specify the light characteristics well
below maximum allowed Imax current, often at Imax/2 or Imax/3 so with
IMax=1 A, the characteristics are specified at 350 mA.

Of course, this requires two or three times the number of LEDs to get
the same light output and hence the lamp is more expensive, but this
extends the usable life time with more than 3 times, thus being more
economical in the long run.

 

[Phil Hobbs]

upsidedown@downunder.com wrote:

On Thu, 19 Jan 2023 16:11:35 +0100, albert@cherry.(none) (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.

Groetjes Albert


The problem with \'white\' LEDs is the degradation of the phosphor with
high currents. Running the LED at Imax and the light output will drop
significantly after a few hundred or a thousand hours. Running at
Imax/2 or even Imax/3 and the light output may be strong after claimed
30000 hours. The efficiency (in lm/W) is also better for the lower
current.

Reputable LED manufacturers specify the light characteristics well
below maximum allowed Imax current, often at Imax/2 or Imax/3 so with
IMax=1 A, the characteristics are specified at 350 mA.

Of course, this requires two or three times the number of LEDs to get
the same light output and hence the lamp is more expensive, but this
extends the usable life time with more than 3 times, thus being more
economical in the long run.

If the phosphor were responsible, you\'d expect the light output to get
bluer and bluer as the lamp aged, which I don\'t think it does.

The phosphor/fluor is inorganic, so it doesn\'t degrade the way organic
dyes do.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Clive Arthur]

On 20/01/2023 17:09, Ricky wrote:

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!

RGB detectors could work for a single tone, but I was hoping for
polyphony. Simply divide the light frequencies by 2^39 or 2^40. Jan
could probably do it with a PIC.

I just remembered - my great niece has a toy Xylophone with a single
octave and the notes are coloured like a rainbow.

--
Cheers
Clive

--
Cheers
Clive

 

[Ricky]

On Friday, January 20, 2023 at 5:50:39 PM UTC-5, Clive Arthur wrote:

On 20/01/2023 17:09, Ricky wrote:
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!
RGB detectors could work for a single tone, but I was hoping for
polyphony. Simply divide the light frequencies by 2^39 or 2^40. Jan
could probably do it with a PIC.

Yeah, they have a special instruction on the PIC for that, but it takes 2^39 cycles. Probably added just for Jan, knowing how many of the devices he uses.

I just remembered - my great niece has a toy Xylophone with a single
octave and the notes are coloured like a rainbow.

LOL, maybe it will sound from the light beams. But isn\'t each note on a xylophone binary, 1/0? I would think you\'d want an analog device.

If you really did that, (not impossible with three sensors, the human eye does it) it would probably sound a lot like noise, unless you had a way to present the sounds in at least 2D. An eye with no spacial distinction wouldn\'t be very useful, to anyone smarter than planaria.

What sort of processing can turn three receptors, RGB, into a spectrum of color? It might take more than a PIC, just sayin...

--

Rick C.

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

 

[whit3rd]

On Friday, January 20, 2023 at 3:50:25 PM UTC-8, Ricky wrote:

On Friday, January 20, 2023 at 5:50:39 PM UTC-5, Clive Arthur wrote:

I just remembered - my great niece has a toy Xylophone with a single
octave and the notes are coloured like a rainbow.
LOL, maybe it will sound from the light beams. But isn\'t each note on a xylophone binary, 1/0? I would think you\'d want an analog device.

If you really did that, (not impossible with three sensors, the human eye does it) it would probably sound a lot like noise, unless you had a way to present the sounds in at least 2D. An eye with no spacial distinction wouldn\'t be very useful, to anyone smarter than planaria.

What sort of processing can turn three receptors, RGB, into a spectrum of color? It might take more than a PIC, just sayin...

An octave or two output is eight to 24 distinct frequencies, not just three.. There are linear-array
sensors that make a spectrum breakdown for visible light easy with prism or grating,
and worst-case the translation to sound from light would just be a 24x24 matrix operating
on a 24-element light sensor \'vector\'. A DSP processor could handle it fine; slight bonus for
using multiple high-Q filters on the 24-element output-with-modulation.

 

[Ricky]

On Friday, January 20, 2023 at 7:25:26 PM UTC-5, whit3rd wrote:

On Friday, January 20, 2023 at 3:50:25 PM UTC-8, Ricky wrote:
On Friday, January 20, 2023 at 5:50:39 PM UTC-5, Clive Arthur wrote:

I just remembered - my great niece has a toy Xylophone with a single
octave and the notes are coloured like a rainbow.
LOL, maybe it will sound from the light beams. But isn\'t each note on a xylophone binary, 1/0? I would think you\'d want an analog device.

If you really did that, (not impossible with three sensors, the human eye does it) it would probably sound a lot like noise, unless you had a way to present the sounds in at least 2D. An eye with no spacial distinction wouldn\'t be very useful, to anyone smarter than planaria.

What sort of processing can turn three receptors, RGB, into a spectrum of color? It might take more than a PIC, just sayin...
An octave or two output is eight to 24 distinct frequencies, not just three. There are linear-array
sensors that make a spectrum breakdown for visible light easy with prism or grating,
and worst-case the translation to sound from light would just be a 24x24 matrix operating
on a 24-element light sensor \'vector\'. A DSP processor could handle it fine; slight bonus for
using multiple high-Q filters on the 24-element output-with-modulation.

I\'m talking about sensing the color of light. The human eye uses three wavelength specific sensors to respond to various spectra of light frequencies..

I don\'t know why you talk about 24 distinct frequencies. The human ear can distinguish much finer resolution in frequency than that!

If you used an array of wavelength specific light sensors, there would be no need for a matrix. Each one would correspond to a wavelength of sound. That would only require a single output channel and it would not require a DSP to handle the processing. An Arduino could do it.

--

Rick C.

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

 

[whit3rd]

On Friday, January 20, 2023 at 6:17:48 PM UTC-8, Ricky wrote:

On Friday, January 20, 2023 at 7:25:26 PM UTC-5, whit3rd wrote:
On Friday, January 20, 2023 at 3:50:25 PM UTC-8, Ricky wrote:
On Friday, January 20, 2023 at 5:50:39 PM UTC-5, Clive Arthur wrote:

I just remembered - my great niece has a toy Xylophone with a single
octave and the notes are coloured like a rainbow.

An octave or two output is eight to 24 distinct frequencies, not just three. There are linear-array
sensors that make a spectrum breakdown for visible light easy with prism or grating,
and worst-case the translation to sound from light would just be a 24x24 matrix operating
on a 24-element light sensor \'vector\'. A DSP processor could handle it fine; slight bonus for
using multiple high-Q filters on the 24-element output-with-modulation.

I\'m talking about sensing the color of light. The human eye uses three wavelength specific sensors to respond to various spectra of light frequencies.

But, mapping that to a sonic output, there\'s a polyphonic opportunty. Consider the light is actually a complete
spectrum (to be mapped to a multiplicity of notes, to make a \'chord\').

> I don\'t know why you talk about 24 distinct frequencies. The human ear can distinguish much finer resolution in frequency than that!

The idea was to use a non-high-fidelity sonic range, like the two-or-three octave range of telephony,
and the diatonic scale, 8 full notes spanning an octave...
Visible light (400 to 700 nm) is less than an octave, some modest frequency-gain in the
range seemed appropriate.

> If you used an array of wavelength specific light sensors, there would be no need for a matrix. Each one would correspond to a wavelength of sound. That would only require a single output channel and it would not require a DSP to handle the processing. An Arduino could do it.

Or, you could pump energy into a tuning fork array (similar to a music box) and
no computation is necessary at all, just a power-of-light dependence for multiple oscillators\'
amplitudes.