LED Bulb Efficiency vs. Operating Life...

[Ricky]

On Saturday, January 21, 2023 at 1:28:07 AM UTC-5, whit3rd wrote:

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\').

Yes, and color is not a 1D phenomenon.

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...

That\'s my point. There\'s a lot more than 8 notes in a music octave. The diatonic scale has 12 notes and musicians often bend those notes. Other scales use even more notes.

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.

Power of light? You\'ve lost me.

--

Rick C.

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

 

[whit3rd]

On Friday, January 20, 2023 at 10:40:37 PM UTC-8, Ricky wrote:

On Saturday, January 21, 2023 at 1:28:07 AM UTC-5, whit3rd wrote:

...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.

Power of light? You\'ve lost me.

I meant to suggest light intensity measured (lux per wavelength-range?) by
the sensor for a segment of the light spectrum. Light measurement
units are many, and confusing (I usually fall back on photon-count).

 

[Jan Panteltje]

On a sunny day (Fri, 20 Jan 2023 23:27:10 -0800 (PST)) it happened whit3rd
<whit3rd@gmail.com> wrote in
<154daade-d50f-435d-9881-b46367657f0en@googlegroups.com>:

On Friday, January 20, 2023 at 10:40:37 PM UTC-8, Ricky wrote:
On Saturday, January 21, 2023 at 1:28:07 AM UTC-5, whit3rd wrote:

...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.

Power of light? You\'ve lost me.

I meant to suggest light intensity measured (lux per wavelength-range?) by
the sensor for a segment of the light spectrum. Light measurement
units are many, and confusing (I usually fall back on photon-count).

In analog color TV
The red green and blue color signals from the cameras are summed taking into account eye sensitivity as
Y = 0.3R +0.59G + 011B (PAL system) where Y is luminance and R, G, and B are red green and blue.

R-Y
and
B-Y
then are used as axis in a vector diagram,
where the vector angle is the color and the vector amplitude the intensity
and R-Y and B-Y are quadrature modulated on the (4.43 MHz for PAL) color subcarrier.
That way for a BW picture the color subcarrier is zero.
The angle of the vector is the color:
http://panteltje.com/pub/vectorscope.gif
its amplitude the saturation

You could then convert that into any audio you want (center frequency and amplitude),
for example 0 degees 100 Hz and 359 degrees 15 kHz
Would probably sound like shit? but OK


The other way around I use just the overlapping filters of an audio equalizer to drive RGB LED strips from audio to make a disco show:
http://panteltje.com/panteltje/xpequ/index.html
http://panteltje.com/panteltje/pic/col_pic/

note the little circle with arrow in color_pic to set any color... It sets basically the vecor diplay angle, so the color
https://www.youtube.com/watch?v=ixoo4ey4b9A
saturation is by a slider, GUI in that circle cannot set vector amplitude.


But for the light show / effect I use
red amplitude is controlled by the lower frequencies, then green midrange, and blue amplitude controlled by the highest frequencies.

well...

 

[Martin Brown]

On 20/01/2023 16:33, Liz Tuddenham wrote:

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

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

...and leaking batteries.

Avoid Duracell and you won\'t have a problem!

I prefer Panasonic and Eveready these days - never had on leak.


--
Regards,
Martin Brown

 

[Martin Brown]

On 20/01/2023 14:05, albert wrote:

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.

It is quite rare now to find that 3 AA\'s & resistor configuration. Most
have either a single AA cell or a pair of them and a voltage to current
converter that drives the stack (or a single one) at constant current.

A single led failing has no consequences.
The failure modes are dropping from two meters on a concrete flour,
and the switch.

The ones that have 3 cells are ideal candidates for bridging the switch
with a 1M resistor so that you can find them in the pitch dark.

They are increasingly rare at least in the UK. Most are now single cell.


--
Regards,
Martin Brown

 

[Martin Brown]

On 20/01/2023 22:18, Phil Hobbs wrote:

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.

I think it is the organic binder or glue that holds it all together that
degrades to become darker with free carbon in it under the influence of
such a high light flux.

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

Moisture ingress appears to be the main mechanism by which the high
intensity ones degrade in the wild. The harder you run them the worse it
gets with differential thermal expansion. eg.

https://www.nature.com/articles/srep24052

--
Regards,
Martin Brown

 

[Jan Panteltje]

On a sunny day (Sat, 21 Jan 2023 11:51:31 +0000) it happened Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tqgjkg$10th$1@gioia.aioe.org>:

On 20/01/2023 16:33, Liz Tuddenham wrote:
albert <albert@cherry.(none)> wrote:

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

...and leaking batteries.

Avoid Duracell and you won\'t have a problem!

I prefer Panasonic and Eveready these days - never had on leak.

In the single AAA cell flashlights I have everywhere I use Eneloop batteries.
Rechargeable, and even if not used in a year still 100% full.
Those are also in most of my remote controls, drone remote too.
and inside/outside temperature meter, radio clock, Creative mp3 player...


The real heavy Cree flashlight I have has one \'Ultrafire 3200mAh 3.7 V\' cell.
Also good charge retention, liion...

But if all else fails I have a light with a handle that you can turn to get power
or even charge some USB stuff.
http://panteltje.com/pub/sources_of_light_IXIMG_0920.JPG

Matches, lighter, candles too.
No worry!

For the bigger stuff, lifepo4 sine wave converter::
http://panteltje.com/pub/250_Ah_12V_to_230V_sinewave_IXXIMG_0796.JPG

There is also this big ball that pops up every morning, gives heat too.

 

[Mike Monett VE3BTI]

Martin Brown <\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

It is quite rare now to find that 3 AA\'s & resistor configuration. Most
have either a single AA cell or a pair of them and a voltage to current
converter that drives the stack (or a single one) at constant current.

I have a number of LED single cell penlights. They produce constant light
output even though the battery voltage is constantly decreasing. I monitor
the battery voltage, and am amazed to find the voltage decreasing to below
1.2V yet the lights still work fine. I wonder what kind of step-up converter
they use that can work at such low voltages.



--
MRM

 

[Martin Brown]

On 21/01/2023 14:01, Mike Monett VE3BTI wrote:

Martin Brown <\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

It is quite rare now to find that 3 AA\'s & resistor configuration. Most
have either a single AA cell or a pair of them and a voltage to current
converter that drives the stack (or a single one) at constant current.

I have a number of LED single cell penlights. They produce constant light
output even though the battery voltage is constantly decreasing. I monitor
the battery voltage, and am amazed to find the voltage decreasing to below
1.2V yet the lights still work fine. I wonder what kind of step-up converter
they use that can work at such low voltages.

It is an IC version of the joule thief circuit but designed to provide
constant current into the LED load until the battery is seriously flat.

https://en.wikipedia.org/wiki/Joule_thief

--
Regards,
Martin Brown

 

[Mike Monett VE3BTI]

Mike Monett VE3BTI <spamme@not.com> wrote:

I have a number of LED single cell penlights. They produce constant
light output even though the battery voltage is constantly decreasing. I
monitor the battery voltage, and am amazed to find the voltage
decreasing to below 1.2V yet the lights still work fine. I wonder what
kind of step-up converter they use that can work at such low voltages.

I found the answer. They use a Diodes Inc. ZXSC310E5 or equivalent:

https://octopart.com/datasheet/zxsc310e5ta-diodes+inc.-590004

It works down to 0.8V, which appears to be the knee of the discharge curve:

https://lygte-info.dk/pic/BatteryLowCurrentDischarge/Carbon-Zinc/Discharge%
20capacity%20Kodak%20Super%20Heavy%20Duty%20AA.png

So my little LED penlights still have lots of life left in them.




--
MRM

 

[Mike Monett VE3BTI]

Martin Brown <\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

It is an IC version of the joule thief circuit but designed to provide
constant current into the LED load until the battery is seriously flat.

https://en.wikipedia.org/wiki/Joule_thief

--
Regards,
Martin Brown

Thanks. I found the answer which I posted earlier.

Don\'t you hate the new Wikipedia format? It squeezes the text into a narrow
column, which increases the amount of scrolling you need to do. I guess the
programmers have too much time on their hands and need to justify their high
pay checks. I wonder if there is any way to revert to the old format. It
worked very well for many years.



--
MRM

 

[Mike Monett VE3BTI]

Mike Monett VE3BTI <spamme@not.com> wrote:

It works down to 0.8V, which appears to be the knee of the discharge curve:

https://lygte-info.dk/pic/BatteryLowCurrentDischarge/Carbon-Zinc/Discharge%
20capacity%20Kodak%20Super%20Heavy%20Duty%20AA.png

Oops - that is carbon-zinc. Alkaline is different. The knee is a bit higher,
around 0.9V - 1.0V

https://www.powerstream.com/z/AA-100mA.png

I shall have to start monitoring the battery voltage when it hits 1V




--
MRM

 

[John Larkin]

On Sat, 21 Jan 2023 11:51:41 +0000, Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 20/01/2023 14:05, albert wrote:
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.

It is quite rare now to find that 3 AA\'s & resistor configuration. Most
have either a single AA cell or a pair of them and a voltage to current
converter that drives the stack (or a single one) at constant current.

The little key-ring LED things often have one cell, one LED, no
resistor.

 

[Phil Hobbs]

Martin Brown wrote:

On 20/01/2023 22:18, Phil Hobbs wrote:
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.

I think it is the organic binder or glue that holds it all together that
degrades to become darker with free carbon in it under the influence of
such a high light flux.

Still you\'d expect a fairly large colour shift, which I don\'t think is
observed.

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

Moisture ingress appears to be the main mechanism by which the high
intensity ones degrade in the wild. The harder you run them the worse it
gets with differential thermal expansion. eg.

https://www.nature.com/articles/srep24052

Interesting, thanks.

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

 

[Martin Brown]

On 21/01/2023 22:33, Phil Hobbs wrote:

Martin Brown wrote:
On 20/01/2023 22:18, Phil Hobbs wrote:
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.

I think it is the organic binder or glue that holds it all together
that degrades to become darker with free carbon in it under the
influence of such a high light flux.

Still you\'d expect a fairly large colour shift, which I don\'t think is
observed.

It is the blue LED to phosphor interface degrading under the flux of
blue photons so I\'d expect comparatively little colour shift if the
intensity of blue light reaching the phosphor is reduced by being
absorbed by carbon black particles before it gets there.

Organic materials don\'t really get on with shorter wavelengths.

--
Regards,
Martin Brown

 

[Phil Hobbs]

Martin Brown wrote:

On 21/01/2023 22:33, Phil Hobbs wrote:
Martin Brown wrote:
On 20/01/2023 22:18, Phil Hobbs wrote:
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.

I think it is the organic binder or glue that holds it all together
that degrades to become darker with free carbon in it under the
influence of such a high light flux.

Still you\'d expect a fairly large colour shift, which I don\'t think is
observed.

It is the blue LED to phosphor interface degrading under the flux of
blue photons so I\'d expect comparatively little colour shift if the
intensity of blue light reaching the phosphor is reduced by being
absorbed by carbon black particles before it gets there.

Organic materials don\'t really get on with shorter wavelengths.

I\'m not at all sure that charring is the mechanism, though. Usually
polymer binders turn a dirty yellow, not grey.

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

 

[Three Jeeps]

On Thursday, January 19, 2023 at 10:37:33 AM UTC-5, Martin Brown wrote:

On 19/01/2023 15:11, albert wrote:
In article <nnd$4d9a769b$61464ae6@e846562bf142425e>,
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.

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.

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

For devices that are suppose to last for quite a long time, putting any light emitting devices in series is really stupid - for one of the reasons you point out. Same issue for the (LED or incandescent) Christmas lights. A vicious plot to drive the consumers crazy and increase profits for the mfg. I\'ve repaired a few monitors that have a LED in series light strip. Sme stupid design. There are a few (2, 3) strips in parallel depending on the size of the monitor but if one strip goes out the brightness goes south quickly.

 

[Three Jeeps]

On Saturday, January 21, 2023 at 6:51:52 AM UTC-5, Martin Brown wrote:

On 20/01/2023 16:33, Liz Tuddenham wrote:
albert <albert@cherry.(none)> wrote:

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

...and leaking batteries.
Avoid Duracell and you won\'t have a problem!

I prefer Panasonic and Eveready these days - never had on leak.


--
Regards,
Martin Brown

+1 on avoiding Duracell. I\'ve never seen a battery other than Duracell where both the + and - endcaps separated themselves from the body. Enloop/Fujitsu or Amazon basic rechargables for the last 5 years for all my devices. Well there are the flashlights that use 14500. Never had any of those fail....

 

[Lasse Langwadt Christensen]

mandag den 23. januar 2023 kl. 01.29.12 UTC+1 skrev jjhu...@gmail.com:

On Thursday, January 19, 2023 at 10:37:33 AM UTC-5, Martin Brown wrote:
On 19/01/2023 15:11, albert wrote:
In article <nnd$4d9a769b$61464ae6@e846562bf142425e>,
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.

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.

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

For devices that are suppose to last for quite a long time, putting any light emitting devices in series is really stupid - for one of the reasons you point out. Same issue for the (LED or incandescent) Christmas lights. A vicious plot to drive the consumers crazy and increase profits for the mfg. I\'ve repaired a few monitors that have a LED in series light strip. Sme stupid design. There are a few (2, 3) strips in parallel depending on the size of the monitor but if one strip goes out the brightness goes south quickly.

if any part of the long filament in a light bulb fails, it goes out and it is scrap ...

 

[Martin Brown]

On 23/01/2023 00:29, Three Jeeps wrote:

On Thursday, January 19, 2023 at 10:37:33 AM UTC-5, Martin Brown
wrote:
On 19/01/2023 15:11, albert wrote:
In article <nnd$4d9a769b$61464ae6@e846562bf142425e>, 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.

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.

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.

For devices that are suppose to last for quite a long time, putting
any light emitting devices in series is really stupid - for one of
the reasons you point out. Same issue for the (LED or incandescent)
Christmas lights.

The old filament ones would be guaranteed not to work out of the box
every year and require at a minimum tightening all the bulbs in their
sockets and more likely a binary chop search to find the failed one.
They also had full mains voltage across the break. Later versions had a
conductive breakdown glass so that if one bulb failed it would provide a
current path but no voltage drop so the rest stay lit but brighter.
There was a fuse lamp to prevent runaway failure if several blew.

Curiously to save wire a lot of the modern LED ones do use long chains
of LEDS and a common earth. I have a set under my desk from the Village
Hall awaiting repair at the moment. Half the LEDs on it don\'t light.

A vicious plot to drive the consumers crazy and
increase profits for the mfg. I\'ve repaired a few monitors that
have a LED in series light strip. Sme stupid design. There are a few
(2, 3) strips in parallel depending on the size of the monitor but if
one strip goes out the brightness goes south quickly.

LEDs are pretty reliable compared to filamen bulbs so it isn\'t all that
crazy a design. The ones I object to are cheap and nasty Chinese
rectified mains ones that put ~100 LEDs in series.

--
Regards,
Martin Brown