In article ,
whisky-dave wrote:
On Friday, 11 November 2016 00:46:59 UTC, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
For dave plowman who has trouble reading it says.
"When the bulb is on for 4 hours a day".

and this is another reason I dim LEDs it's not brightnes or to save
money on electricity costs.

So that's why you keep on having to buy new dimmers?

No thicko. I've not brought a new dimmer since I replaced my faulty one
with a working one.

But true thicko DIYer's such as me repair dimmers. What does that make you?


BTW, have you any data to prove altering the waveform into the LED PS
will actually improve the life? My guess is not.

No why would I, as it has nothing to do with it. You just have no idea
have you, it's the temperature that that's the key. We're running a lab
on that today. Where students 'roast' an LED. The ide is they hold a
solderign iron up to the LED to make it hot and to destroy it by just
heat no voltage applied. Make : Electronics Second edition by charles
platt Experiment 13 Roasting an LED Page 121.

Sorry for assuming you had some idea of the sort of power supply used in a
mains LED. I'll know better in future.


Get this book and learn something just for once.

we brought about 60
https://www.amazon.co.uk/Make-Electr.../dp/1680450263

Hope it is better than the LadyBird book you seem to have got most of your
'knowledge' from.

--
*If I agreed with you, we'd both be wrong.

Dave Plowman London SW
To e-mail, change noise into sound.

On Friday, 11 November 2016 14:55:26 UTC, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
On Friday, 11 November 2016 00:46:59 UTC, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
For dave plowman who has trouble reading it says.
"When the bulb is on for 4 hours a day".

and this is another reason I dim LEDs it's not brightnes or to save
money on electricity costs.

So that's why you keep on having to buy new dimmers?

No thicko. I've not brought a new dimmer since I replaced my faulty one
with a working one.

But true thicko DIYer's such as me repair dimmers. What does that make you?

Clever than you because I knew fixing the dimmer would not make it do what I wanted which was to dim LEDs

you still haven;t got this basic fact righ thave you.

It's really simple but you get it wrong everytime.

Dimmable LEDs require a trailing edge dimmer if they are to dim properly.




BTW, have you any data to prove altering the waveform into the LED PS
will actually improve the life? My guess is not.

No why would I, as it has nothing to do with it. You just have no idea
have you, it's the temperature that that's the key. We're running a lab
on that today. Where students 'roast' an LED. The ide is they hold a
solderign iron up to the LED to make it hot and to destroy it by just
heat no voltage applied. Make : Electronics Second edition by charles
platt Experiment 13 Roasting an LED Page 121.

Sorry for assuming you had some idea of the sort of power supply used in a
mains LED. I'll know better in future.

I know far more than you do.

On 11/11/2016 11:11, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
Heh heh. If the average life of an LED was actually 15 years, why don't
they give them a lifetime warrenty? The number of people who could produce
a receipt after 15 years would be very very small.

The LEDs themselves are incredibly reliable provided that you don't
abuse them. I find dipping the old dim ones in LN2 to demonstrate the
improvement in efficiency with a cooled more rigid crystal lattice tends
to do for them after a while, but indicator LEDs I installed when they
were new and novel in the mid 70's are still going strong. Unlike the
old low voltage indicator bulbs they are almost indestructible.

Yes - same here. But once you start driving a LED hard to use as a light
source, the life comes down.
I've had a couple of early ones explode. And they claimed a very long life
too. Given their high cost put me off them - especially since the light
they produced was terrible.

Yup early LED lights were fairly horrible in terms of the colour and
quality of the light - quite often as bad or worse than CFLs.

The modern ones however have got vastly better - to the point now where
I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp (both in terms of light quality
and also directionality). (the non filament ones can also do decent
light, but have a different illumination pattern from a traditional GLS).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 11/11/2016 09:47, dennis@home wrote:
On 11/11/2016 00:45, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
It actually says: "Manufacturers will give lifetime claims in multiples
of 1000 hours. One thousand hours is equivalent to about 6-months use
when the bulb is on for 4 hours per day. A traditional halogen spotlight
bulb is expected to last about one year (2000 hours) where as an LED
will last between 30,000 and 50,000 hours - that‘s between 15 and 25
years! Switching to LEDs means you may never have to change your light
bulbs again.",


Heh heh. If the average life of an LED was actually 15 years, why don't
they give them a lifetime warrenty? The number of people who could
produce
a receipt after 15 years would be very very small.


If you sold 10 million of them and 0.01% claimed each year you would
need quite a few people to keep up with the claims.
It just wouldn't be economical on the margins they make.

LED hut offer a 5 year warranty on theirs. They honour it as well, on
the couple of occasions I have had failures a quick email has been
enough to have a replacement at my door next day.

One car manufacturer offered lifetime warranties for a while but they
stopped doing it.

Lifetime is also rather difficult to understand exactly what is on
offer. I remember a disk company offering such a warranty on their
floppy disks once. Turned out when you read the small print the
"lifetime" was defined as the period from new until the media developed
read/write errors!


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 11/11/2016 11:17, Dave Plowman (News) wrote:
In article . com,
dennis@home wrote:
On 11/11/2016 00:45, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
It actually says: "Manufacturers will give lifetime claims in multiples
of 1000 hours. One thousand hours is equivalent to about 6-months use
when the bulb is on for 4 hours per day. A traditional halogen spotlight
bulb is expected to last about one year (2000 hours) where as an LED
will last between 30,000 and 50,000 hours - that‘s between 15 and 25
years! Switching to LEDs means you may never have to change your light
bulbs again.",


Heh heh. If the average life of an LED was actually 15 years, why don't
they give them a lifetime warrenty? The number of people who could produce
a receipt after 15 years would be very very small.


If you sold 10 million of them and 0.01% claimed each year you would
need quite a few people to keep up with the claims.
It just wouldn't be economical on the margins they make.

Are you then saying none ever fail within the existing warranty period?
Most things are likely (percentage wise) to fail early on. If not, last
the design life before failing. The bathtub effect.

One car manufacturer offered lifetime warranties for a while but they
stopped doing it.

How long a car lasts depends on lots of things. Like type of use and
servicing, etc. That doesn't apply to a lamp.

It does to a fair extent... with LEDs its particularly effected by how
hot it is allowed to get.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 11/11/2016 08:54, The Natural Philosopher wrote:
On 10/11/16 17:57, John Rumm wrote:
On 10/11/2016 10:35, whisky-dave wrote:
On Wednesday, 9 November 2016 18:02:43 UTC, John Rumm wrote:

Another problem with many LED lamps is the electronic drivers don't
like heat much either. So if your lamp base has an electrolytic cap
in it (as many do) its not going to last long at over 100 degrees.

same thing happened with PC PSUs a while back someone had one the
other day and I brought some capacitors rated at 130C 2000hrs I
think, you can get 105C and the normal range are mostly 85C. This is
why a lot of LED lamps donl;t last the 50K hours stated, if you read
the full specs some are only rates at 50K if you use them for less
than x hours at a time.

Yup indeed. I retired a GU10 spot the other day that was still working
LED wise, but was flickering because the cap in its base had lost so
much capacitance.


Of course there are some 'ankers on her that will say I'm wrong. So
before tehy embarress themselfs lijke a high wranking academci
telling me there no such thing as the factories and workplaces
act.....

https://www.ledhut.co.uk/spot-lights...placement.html



Go to the specs tab on the 3.6 Watt GU10 LED Spotlight - 35W
Replacement
hover the mouse over the average life hrs the green.

For dave plowman who has trouble reading it says. "When the bulb is
on for 4 hours a day".

It actually says: "Manufacturers will give lifetime claims in multiples
of 1000 hours. One thousand hours is equivalent to about 6-months use
when the bulb is on for 4 hours per day. A traditional halogen spotlight
bulb is expected to last about one year (2000 hours) where as an LED
will last between 30,000 and 50,000 hours - thats between 15 and 25
years! Switching to LEDs means you may never have to change your light
bulbs again.",


So fas so good...

which (to me at least) does not seem to imply any maximum duty cycle or
period of on time to achieve that lifetime on that particular product.

???WTF does '4 hours a day' mean if it doesn't mean 'duty cycle'

Its simply attempting to give an example of the likely replacement
schedule based on "typical" use, for some value of "typical" which they
then go on to define for the pedants ;-)

30,000 hours is about 4 years if you leave it on all the time.

Indeed.

The box for the LED candle I have beside me, makes the claim that it has
a 12 year lifespan - but that is based on its 20,000 hours being used
4.5 hours / day.

The life will scale down (and possibly up) for longer or shorter daily
run times pro rata.

Around 1960 my late data rigged up a fluorescent tube in the garage, he
died a couple of years later, but that tube was still there working,
though it flickered badly, when the house was sold in 2004.

It probably was on for less than an hour a month.

ISTR there was mine somewhere where it was lit by similar tubes, which
had been running 24/7 for decades. The fact that they were in a nice
stable temperature and never turned off meant they had exceptional run
times.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp

I find the "filament" LEDs are only good for an enclosed/diffused shade,
they are very glary if the actual lamp is in sight.

In article ,
John Rumm wrote:
How long a car lasts depends on lots of things. Like type of use and
servicing, etc. That doesn't apply to a lamp.

It does to a fair extent... with LEDs its particularly effected by how
hot it is allowed to get.

As regards straightforward replacement of tungsten with LED are going to
be just fine with cooling if they were OK for tungsten. Could well be
different with totally enclosed fittings - but they're going to be a small
percentage. If the big variety of fitting I have in this house are
anything to go by.

With a car, it doesn't take too much imagination to see that one which is
abused isn't going to have as long a life as one driven sympathetically.

With a light, you don't have any choice other than on or off.

--
*How many roads must a man travel down before he admits he is lost?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
John Rumm wrote:
Yup early LED lights were fairly horrible in terms of the colour and
quality of the light - quite often as bad or worse than CFLs.

Worse, IMHO. Unless you liked 'blue' light.

The modern ones however have got vastly better - to the point now where
I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp (both in terms of light quality
and also directionality). (the non filament ones can also do decent
light, but have a different illumination pattern from a traditional GLS).

Yes - they are improving all the time. Which is odd since so many thought
them perfect when they first arrived. Difficult to improve perfection. ;-)

--
*White with a hint of M42*

Dave Plowman London SW
To e-mail, change noise into sound.

On Friday, 11 November 2016 15:55:08 UTC, Andy Burns wrote:
John Rumm wrote:

I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp

I find the "filament" LEDs are only good for an enclosed/diffused shade,
they are very glary if the actual lamp is in sight.

The one I borrowed only lasted about 5 hours.

On Friday, 11 November 2016 16:04:53 UTC, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
How long a car lasts depends on lots of things. Like type of use and
servicing, etc. That doesn't apply to a lamp.

It does to a fair extent... with LEDs its particularly effected by how
hot it is allowed to get.

As regards straightforward replacement of tungsten with LED are going to
be just fine with cooling if they were OK for tungsten.

Try reading the specs supplied with those LED lamps.
Then try to understand what they mean.

Could well be
different with totally enclosed fittings - but they're going to be a small
percentage. If the big variety of fitting I have in this house are
anything to go by.

With a car, it doesn't take too much imagination to see that one which is
abused isn't going to have as long a life as one driven sympathetically.

What do you mean by abused ?


With a light, you don't have any choice other than on or off.

Some people have the ability and the technology to dim them.
Some use edge triggering while others use PWM if run from DC.

"whisky-dave" wrote in message
...
On Friday, 11 November 2016 16:04:53 UTC, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
How long a car lasts depends on lots of things. Like type of use and
servicing, etc. That doesn't apply to a lamp.

It does to a fair extent... with LEDs its particularly effected by how
hot it is allowed to get.

As regards straightforward replacement of tungsten with LED are going to
be just fine with cooling if they were OK for tungsten.

Try reading the specs supplied with those LED lamps.
Then try to understand what they mean.

Could well be
different with totally enclosed fittings - but they're going to be a
small
percentage. If the big variety of fitting I have in this house are
anything to go by.

With a car, it doesn't take too much imagination to see that one which is
abused isn't going to have as long a life as one driven sympathetically.

What do you mean by abused ?


With a light, you don't have any choice other than on or off.

Some people have the ability and the technology to dim them.
Some use edge triggering while others use PWM if run from DC.

Yebut, PWM IS on or off.
LOL

On Friday, 11 November 2016 16:20:18 UTC, bm wrote:
"whisky-dave" wrote in message
...
On Friday, 11 November 2016 16:04:53 UTC, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
How long a car lasts depends on lots of things. Like type of use and
servicing, etc. That doesn't apply to a lamp.

It does to a fair extent... with LEDs its particularly effected by how
hot it is allowed to get.

As regards straightforward replacement of tungsten with LED are going to
be just fine with cooling if they were OK for tungsten.

Try reading the specs supplied with those LED lamps.
Then try to understand what they mean.

Could well be
different with totally enclosed fittings - but they're going to be a
small
percentage. If the big variety of fitting I have in this house are
anything to go by.

With a car, it doesn't take too much imagination to see that one which is
abused isn't going to have as long a life as one driven sympathetically.

What do you mean by abused ?


With a light, you don't have any choice other than on or off.

Some people have the ability and the technology to dim them.
Some use edge triggering while others use PWM if run from DC.

Yebut, PWM IS on or off.
LOL

In the same way as AC is never on as it's always changing so it to is only ever off or on.

On 11/11/16 12:44, Roger Hayter wrote:


Is it reallly possible to design a DC to DC converter that is both
stable and efficient without using large value electrolytics?


Yes up to a point.

But you need to go quite high in frequency which makes some parts cost
more, RF emissions get to be an issue, and efficiency can drop as well.

--
"It is an established fact to 97% confidence limits that left wing
conspirators see right wing conspiracies everywhere"

On 11/11/16 15:36, John Rumm wrote:
On 11/11/2016 11:11, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
Heh heh. If the average life of an LED was actually 15 years, why don't
they give them a lifetime warrenty? The number of people who could
produce
a receipt after 15 years would be very very small.

The LEDs themselves are incredibly reliable provided that you don't
abuse them. I find dipping the old dim ones in LN2 to demonstrate the
improvement in efficiency with a cooled more rigid crystal lattice tends
to do for them after a while, but indicator LEDs I installed when they
were new and novel in the mid 70's are still going strong. Unlike the
old low voltage indicator bulbs they are almost indestructible.

Yes - same here. But once you start driving a LED hard to use as a light
source, the life comes down.
I've had a couple of early ones explode. And they claimed a very long
life
too. Given their high cost put me off them - especially since the light
they produced was terrible.

Yup early LED lights were fairly horrible in terms of the colour and
quality of the light - quite often as bad or worse than CFLs.

The modern ones however have got vastly better - to the point now where
I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp (both in terms of light quality
and also directionality). (the non filament ones can also do decent
light, but have a different illumination pattern from a traditional GLS).

I actually *prefer* modern LED bulbs to filaments




--
The biggest threat to humanity comes from socialism, which has utterly
diverted our attention away from what really matters to our existential
survival, to indulging in navel gazing and faux moral investigations
into what the world ought to be, whilst we fail utterly to deal with
what it actually is.

On 11/11/2016 15:36, John Rumm wrote:
On 11/11/2016 11:11, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
Heh heh. If the average life of an LED was actually 15 years, why don't
they give them a lifetime warrenty? The number of people who could
produce
a receipt after 15 years would be very very small.

The LEDs themselves are incredibly reliable provided that you don't
abuse them. I find dipping the old dim ones in LN2 to demonstrate the
improvement in efficiency with a cooled more rigid crystal lattice tends
to do for them after a while, but indicator LEDs I installed when they
were new and novel in the mid 70's are still going strong. Unlike the
old low voltage indicator bulbs they are almost indestructible.

Yes - same here. But once you start driving a LED hard to use as a light
source, the life comes down.
I've had a couple of early ones explode. And they claimed a very long
life
too. Given their high cost put me off them - especially since the light
they produced was terrible.

Yup early LED lights were fairly horrible in terms of the colour and
quality of the light - quite often as bad or worse than CFLs.

I didn't consider them worth having until the price became comparable
with CFLs - then bought a couple on special offer and never looked back.

The modern ones however have got vastly better - to the point now where
I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp (both in terms of light quality
and also directionality). (the non filament ones can also do decent
light, but have a different illumination pattern from a traditional GLS).

Indeed. And the only criticism I have of the previous generation of
Philips LED spotlamps is that they are too well collimated and
directional. The other notable thing is that the LED functional
equivalent to a nominal 60W incandescent is way brighter than the poxy
output of a CFL claiming to be a "nominal" 60W. I got caught out with my
first ever 60W equivalent LED being far too bright!

--
Regards,
Martin Brown

On 11/11/2016 12:44, Roger Hayter wrote:
Syd Rumpo wrote:

A DC supply would be better as you wouldn't need relatively large
electrolytics in the internal LED switch mode PSU which have a limited
life or a high cost. If you're using DC, 48V would be a good choice as
it's high enough not to need too thick wires (given that LEDs use less
current than incandescents) and low enough not to be a shock hazard.

No point replacing existing wiring, but maybe one day for new buildings.

Is it reallly possible to design a DC to DC converter that is both
stable and efficient without using large value electrolytics?

It probably wouldn't be done that way. You can design highly efficient
voltage to constant current converters which provide the drive that LEDs
actually require. They are current based devices with a terminal voltage
that varies somewhat with applied current and temperature.

Crude resistor based current limiting is used in some torches but chips
to do this job cheaply and efficiently are quite common now.

--
Regards,
Martin Brown

On 11/11/2016 11:41, Roger Hayter wrote:
Rod Speed wrote:

"Dave Plowman (News)" wrote in message
...
In article 2,
DerbyBorn wrote:


All semiconductors need to be kept relatively cool. A max of about
200C comes to mind from years ago.

Capacitors too have a shorter life with heat. And SWPS rely on fairly
high stressed caps.


I have some kitchen downlights (Halers) where the driver assembly is
separate from the lamp unit. They have a 7 year warranty - I guess this
is the way to go. Imagine the electronics in a "ceiling rose) and the
lamp on a pendant. I guess that would work. However, makers have felt
pressure to make everything fit a conventional lamp envelope.

True. And the same applied to CFL. Making any energy saving type which
needs a power supply of some sort with the PS built in is invariably a
compromise. I'm rather surprised new standard lighting wiring for LEDs -
perhaps with a central power supply or two - hasn't been devised.

Already there, often with 12V for the LEDs themselves.

Same with low voltage halogens.

But this does not solve the problem. Bare LEDs (the diodes themselves)
are not happy at a fixed voltage, they need circuitry to control the
current through them. So a 12V 'LED bulb" is little different from a
240v one in the complexity of circuit required.

For a constant current drive then yes, but one advantage of a lower
starting voltage is that some multiple of LED voltage drop plus a simple
passive resistor can be made to work without any failure prone
electrolytic capacitors. Plenty of torches use this method although an
increasing number now use a cheap small flyback step up current source
and just a single cell battery.

And even if it was possible to run LEDs from a remote power supply,
there would still be the problem of a keeping the actual diode, itself a
semiconductor, adequately cooled.

The problem invariably boils down to thermal management of the waste
heat generated in the LED chip itself otherwise the phosphor gets
degraded and they are less efficient when run hot. It isn't for nothing
that manufacturers maximum output claims are based on 25C and a nearly
infinite heatsink compared to what a consumer lamp will have.

The only good engineering solution is a light fitting containing the
circuitry to work from a fixed voltags supply (which might just as well
be 240v AC as anything else) and designed to allow appropriate cooling
both for the LED and the associated electronics.

It is invariably the capacitors that go first when used in existing
luminaires designed for hot incandescent bulbs.


--
Regards,
Martin Brown

"Roger Hayter" wrote in message
...
Rod Speed wrote:

"Dave Plowman (News)" wrote in message
...
In article 2,
DerbyBorn wrote:


All semiconductors need to be kept relatively cool. A max of about
200C comes to mind from years ago.

Capacitors too have a shorter life with heat. And SWPS rely on
fairly
high stressed caps.


I have some kitchen downlights (Halers) where the driver assembly is
separate from the lamp unit. They have a 7 year warranty - I guess
this
is the way to go. Imagine the electronics in a "ceiling rose) and the
lamp on a pendant. I guess that would work. However, makers have felt
pressure to make everything fit a conventional lamp envelope.

True. And the same applied to CFL. Making any energy saving type which
needs a power supply of some sort with the PS built in is invariably a
compromise. I'm rather surprised new standard lighting wiring for
LEDs -
perhaps with a central power supply or two - hasn't been devised.

Already there, often with 12V for the LEDs themselves.

Same with low voltage halogens.

But this does not solve the problem.

It is an example of a CENTRAL POWER SUPPLY OR TWO.

Bare LEDs (the diodes themselves) are not happy at a fixed
voltage, they need circuitry to control the current through them.

And that is what the central power supply or two does.

So a 12V 'LED bulb" is little different from a
240v one in the complexity of circuit required.

But very different with the central power supply or two.

And even if it was possible to run LEDs from a remote power supply,

Corse it is. The LED strips do that.

there would still be the problem of a keeping the actual
diode, itself a semiconductor, adequately cooled.

You could get real radical and use an aluminium profile
like the led strips do.

The only good engineering solution is a light fitting containing
the circuitry to work from a fixed voltags supply

How odd that the LED strips don’t do it that way.

(which might just as well be 240v AC as anything else)

How odd that the LED strips don’t do it that way.

They don’t for a reason.

and designed to allow appropriate cooling
both for the LED and the associated electronics.

Don’t need that if the associated electronics
is in a central power supply or two. There is
nothing special about say a 12V 5A power
supply, as used with those LED strips.

"Roger Hayter" wrote in message
...
Syd Rumpo wrote:

On 11/11/2016 11:41, Roger Hayter wrote:
Rod Speed wrote:

"Dave Plowman (News)" wrote in message
...
In article 2,
DerbyBorn wrote:


All semiconductors need to be kept relatively cool. A max of about
200C comes to mind from years ago.

Capacitors too have a shorter life with heat. And SWPS rely on
fairly
high stressed caps.


I have some kitchen downlights (Halers) where the driver assembly is
separate from the lamp unit. They have a 7 year warranty - I guess
this
is the way to go. Imagine the electronics in a "ceiling rose) and
the
lamp on a pendant. I guess that would work. However, makers have
felt
pressure to make everything fit a conventional lamp envelope.

True. And the same applied to CFL. Making any energy saving type
which
needs a power supply of some sort with the PS built in is invariably
a
compromise. I'm rather surprised new standard lighting wiring for
LEDs -
perhaps with a central power supply or two - hasn't been devised.

Already there, often with 12V for the LEDs themselves.

Same with low voltage halogens.

But this does not solve the problem. Bare LEDs (the diodes themselves)
are not happy at a fixed voltage, they need circuitry to control the
current through them. So a 12V 'LED bulb" is little different from a
240v one in the complexity of circuit required.

And even if it was possible to run LEDs from a remote power supply,
there would still be the problem of a keeping the actual diode, itself
a
semiconductor, adequately cooled.

The only good engineering solution is a light fitting containing the
circuitry to work from a fixed voltags supply (which might just as well
be 240v AC as anything else) and designed to allow appropriate cooling
both for the LED and the associated electronics.

A DC supply would be better as you wouldn't need relatively large
electrolytics in the internal LED switch mode PSU which have a limited
life or a high cost. If you're using DC, 48V would be a good choice as
it's high enough not to need too thick wires (given that LEDs use less
current than incandescents) and low enough not to be a shock hazard.

No point replacing existing wiring, but maybe one day for new buildings.

Cheers

Is it reallly possible to design a DC to DC converter that is both
stable and efficient without using large value electrolytics?

Yes, but you don’t need to when you have a central power supply
or two and have that isolated from the heat that the LEDs produce.

That’s how the LED strips work, the power supply is physically
separate from the LEDs.

On 11/11/2016 00:49, bm wrote:
Reminds me of our local barber.
OAPs cut free when accompanied by a parent.

I was just reading of someone who has moved into the same sheltered
development as his mother (she was having so much fun!). He's 65, she's
90. I wonder how often they get hit?

Andy

On 11/11/2016 15:55, Andy Burns wrote:
John Rumm wrote:

I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp

I find the "filament" LEDs are only good for an enclosed/diffused shade,
they are very glary if the actual lamp is in sight.

If you want the same effect as a clear glass GLS, then they are fairly
comparable, but otherwise they work well behind shades etc.

Unlike the ones with frosted dome and an opaque base, they give the full
close to 360 degree output pattern you get from a GLS.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 11/11/2016 16:41, The Natural Philosopher wrote:
On 11/11/16 15:36, John Rumm wrote:
On 11/11/2016 11:11, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
Heh heh. If the average life of an LED was actually 15 years, why
don't
they give them a lifetime warrenty? The number of people who could
produce
a receipt after 15 years would be very very small.

The LEDs themselves are incredibly reliable provided that you don't
abuse them. I find dipping the old dim ones in LN2 to demonstrate the
improvement in efficiency with a cooled more rigid crystal lattice
tends
to do for them after a while, but indicator LEDs I installed when they
were new and novel in the mid 70's are still going strong. Unlike the
old low voltage indicator bulbs they are almost indestructible.

Yes - same here. But once you start driving a LED hard to use as a light
source, the life comes down.
I've had a couple of early ones explode. And they claimed a very long
life
too. Given their high cost put me off them - especially since the light
they produced was terrible.

Yup early LED lights were fairly horrible in terms of the colour and
quality of the light - quite often as bad or worse than CFLs.

The modern ones however have got vastly better - to the point now where
I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp (both in terms of light quality
and also directionality). (the non filament ones can also do decent
light, but have a different illumination pattern from a traditional GLS).

I actually *prefer* modern LED bulbs to filaments

For some applications I do as well. For example in my office I want a
more "work like" light, and so have 5x 60W equiv "daylight" lamps, and
that gives a good light that is easy to read and work in. Its also
bright enough to not seem "blue".


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 11/11/2016 17:44, Martin Brown wrote:
On 11/11/2016 15:36, John Rumm wrote:
On 11/11/2016 11:11, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
Heh heh. If the average life of an LED was actually 15 years, why
don't
they give them a lifetime warrenty? The number of people who could
produce
a receipt after 15 years would be very very small.

The LEDs themselves are incredibly reliable provided that you don't
abuse them. I find dipping the old dim ones in LN2 to demonstrate the
improvement in efficiency with a cooled more rigid crystal lattice
tends
to do for them after a while, but indicator LEDs I installed when they
were new and novel in the mid 70's are still going strong. Unlike the
old low voltage indicator bulbs they are almost indestructible.

Yes - same here. But once you start driving a LED hard to use as a light
source, the life comes down.
I've had a couple of early ones explode. And they claimed a very long
life
too. Given their high cost put me off them - especially since the light
they produced was terrible.

Yup early LED lights were fairly horrible in terms of the colour and
quality of the light - quite often as bad or worse than CFLs.

I didn't consider them worth having until the price became comparable
with CFLs - then bought a couple on special offer and never looked back.

The modern ones however have got vastly better - to the point now where
I find the LED "filament" style lamps produce a light quality hard to
distinguish from a real filament lamp (both in terms of light quality
and also directionality). (the non filament ones can also do decent
light, but have a different illumination pattern from a traditional GLS).

Indeed. And the only criticism I have of the previous generation of
Philips LED spotlamps is that they are too well collimated and
directional. The other notable thing is that the LED functional
equivalent to a nominal 60W incandescent is way brighter than the poxy
output of a CFL claiming to be a "nominal" 60W. I got caught out with my
first ever 60W equivalent LED being far too bright!

The CFLs tended to claim surveillance to a "soft tone" GLS lamp which is
dimmer than a "normal" 60W in the first place, and thats before they
start with the outright bull claims they heaped on top!

The first spots I got (3 LED cree) were ok, but were still slightly
discontinuous in spectrum - lacking a bit at the red end. I found I
needed to run a couple of 20W halogens in the multi way fitting to get a
comfortable light from them. The last couple of LED hut "warm white" LED
GZ10 replacements I got recently, are actually better and would be fine
on their own without any halogen infill.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Martin Brown wrote:

On 11/11/2016 12:44, Roger Hayter wrote:
Syd Rumpo wrote:

A DC supply would be better as you wouldn't need relatively large
electrolytics in the internal LED switch mode PSU which have a limited
life or a high cost. If you're using DC, 48V would be a good choice as
it's high enough not to need too thick wires (given that LEDs use less
current than incandescents) and low enough not to be a shock hazard.

No point replacing existing wiring, but maybe one day for new buildings.

Is it reallly possible to design a DC to DC converter that is both
stable and efficient without using large value electrolytics?

It probably wouldn't be done that way. You can design highly efficient
voltage to constant current converters which provide the drive that LEDs
actually require. They are current based devices with a terminal voltage
that varies somewhat with applied current and temperature.

Crude resistor based current limiting is used in some torches but chips
to do this job cheaply and efficiently are quite common now.

They still reduce efficiency and produce heat unless there are multiple
LEDs which need a voltage near to the supply. Maybe that this the way
to do it, like the LED strips.

--

Roger Hayter

In article ,
whisky-dave wrote:
With a car, it doesn't take too much imagination to see that one which
is abused isn't going to have as long a life as one driven
sympathetically.

What do you mean by abused ?

Since you don't drive or know anything about cars, why ask?

--
*The last thing I want to do is hurt you. But it's still on my list.

Dave Plowman London SW
To e-mail, change noise into sound.

On 11/11/2016 13:54, whisky-dave wrote:



Get this book and learn something just for once.

Or find an on-line preview copy.

After destroying a LED with a soldering iron..... The instruction to the students, presumably young children, is to take a
mains power cord with an USA plug, chop the middle out of it and solder
the two cut ends to make a shorter mains power cord.

There is also a chapter on learning how to burn yourself, choke yourself
on fumes from burning insulation and lose any eye from flying debris by
shorting out a battery and waiting for at least two minutes.


--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

whisky-dave wrote
dennis@home wrote
Dave Plowman (News) wrote
John Rumm wrote

It actually says: "Manufacturers will give lifetime claims in multiples
of 1000 hours. One thousand hours is equivalent to about 6-months use
when the bulb is on for 4 hours per day. A traditional halogen
spotlight
bulb is expected to last about one year (2000 hours) where as an LED
will last between 30,000 and 50,000 hours - that€˜s between 15 and 25
years! Switching to LEDs means you may never have to change your light
bulbs again.",

Heh heh. If the average life of an LED was actually 15 years, why don't
they give them a lifetime warrenty? The number of people who could
produce a receipt after 15 years would be very very small.

If you sold 10 million of them and 0.01% claimed each year
you would need quite a few people to keep up with the claims.
It just wouldn't be economical on the margins they make.

But it doesn;t stop them doing it because they know few will
attempt to claim and those that do you cabn ask have you ever
had them on for more than 4 hours at a time. If they asnwer yes
(which most peolpe will have had) then the warrently is invalid

Wrong. The warranty never says that you can't have them on for longer than 4
hours.

You have utterly mangled what they do say about 4 hours, as always.

just as it would be if the do not remove sticker was removed.

Wrong, as always. You still have the warranty if you remove that.

That's the law.

One car manufacturer offered lifetime warranties
for a while but they stopped doing it.

"whisky-dave" wrote in message
...
On Friday, 11 November 2016 11:21:13 UTC, Dave Plowman (News) wrote:
In article . com,
dennis@home wrote:
On 11/11/2016 00:45, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
It actually says: "Manufacturers will give lifetime claims in
multiples
of 1000 hours. One thousand hours is equivalent to about 6-months
use
when the bulb is on for 4 hours per day. A traditional halogen
spotlight
bulb is expected to last about one year (2000 hours) where as an LED
will last between 30,000 and 50,000 hours - that€˜s between 15 and 25
years! Switching to LEDs means you may never have to change your
light
bulbs again.",


Heh heh. If the average life of an LED was actually 15 years, why
don't
they give them a lifetime warrenty? The number of people who could
produce
a receipt after 15 years would be very very small.


If you sold 10 million of them and 0.01% claimed each year you would
need quite a few people to keep up with the claims.
It just wouldn't be economical on the margins they make.

Are you then saying none ever fail within the existing warranty period?
Most things are likely (percentage wise) to fail early on. If not, last
the design life before failing. The bathtub effect.

One car manufacturer offered lifetime warranties for a while but they
stopped doing it.

How long a car lasts depends on lots of things. Like type of use and
servicing, etc. That doesn't apply to a lamp.

types of use does.
Hence the 4 hours per day,

They dont say it can only be on for 4 hours a day.

Andy Burns wrote
John Rumm wrote

I find the LED "filament" style lamps produce a light
quality hard to distinguish from a real filament lamp

I find the "filament" LEDs are only good for an enclosed/diffused
shade, they are very glary if the actual lamp is in sight.

Just as true of normal GLS bulbs too.

"whisky-dave" wrote in message
...
On Friday, 11 November 2016 16:04:53 UTC, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
How long a car lasts depends on lots of things. Like type of use and
servicing, etc. That doesn't apply to a lamp.

It does to a fair extent... with LEDs its particularly effected by how
hot it is allowed to get.

As regards straightforward replacement of tungsten with LED are going to
be just fine with cooling if they were OK for tungsten.

Try reading the specs supplied with those LED lamps.
Then try to understand what they mean.

Something you can't manage with the 4 hours bit.

On Saturday, 12 November 2016 06:42:03 UTC, Rod Speed wrote:
Andy Burns wrote
John Rumm wrote

I find the LED "filament" style lamps produce a light
quality hard to distinguish from a real filament lamp

I find the "filament" LEDs are only good for an enclosed/diffused
shade, they are very glary if the actual lamp is in sight.

Just as true of normal GLS bulbs too.

LEDs have come a long way since the LED watch that I wore in 1975 and the LED bike lights I had in 1998.

https://pbs.twimg.com/media/CwPKFHsXgAAsjbx.jpg

"Simon Mason" wrote in message
...
On Saturday, 12 November 2016 06:42:03 UTC, Rod Speed wrote:
Andy Burns wrote
John Rumm wrote

I find the LED "filament" style lamps produce a light
quality hard to distinguish from a real filament lamp

I find the "filament" LEDs are only good for an enclosed/diffused
shade, they are very glary if the actual lamp is in sight.

Just as true of normal GLS bulbs too.

LEDs have come a long way since the LED watch that I wore in 1975 and the
LED bike lights I had in 1998.

https://pbs.twimg.com/media/CwPKFHsXgAAsjbx.jpg

Yep, and the simple leds well before that too.

In article ,
Simon Mason wrote:
LEDs have come a long way since the LED watch that I wore in 1975 and
the LED bike lights I had in 1998.

If only you had too.

--
*I got a sweater for Christmas. I really wanted a screamer or a moaner*

Dave Plowman London SW
To e-mail, change noise into sound.

On Saturday, 12 November 2016 11:45:14 UTC, Dave Plowman (News) wrote:
In article ,
Simon Mason wrote:
LEDs have come a long way since the LED watch that I wore in 1975 and
the LED bike lights I had in 1998.

If only you had too.


Did I tell you that when I had that LED watch in 1975, a girl in my class at school had an LCD watch as her Dad had invented them?

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

On 11/11/2016 23:56, John Rumm wrote:
The CFLs tended to claim surveillance to a "soft tone" GLS lamp

What did that say before the spiel chucker got it?

Andy

On 13/11/2016 21:04, Vir Campestris wrote:
On 11/11/2016 23:56, John Rumm wrote:
The CFLs tended to claim surveillance to a "soft tone" GLS lamp

What did that say before the spiel chucker got it?

Equivalence ;-)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Saturday, 12 November 2016 01:18:27 UTC, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
With a car, it doesn't take too much imagination to see that one which
is abused isn't going to have as long a life as one driven
sympathetically.

What do you mean by abused ?

Since you don't drive or know anything about cars, why ask?

What makes you think I don't knnow anything about cars. ?


You don't know anythiung about LEDs.

On Saturday, 12 November 2016 04:36:18 UTC, alan_m wrote:
On 11/11/2016 13:54, whisky-dave wrote:



Get this book and learn something just for once.

Or find an on-line preview copy.

After destroying a LED with a soldering iron.....

Quote:

what else can you do with your newly acquired soldering skills?

The instruction to the students, presumably young children, is to take a
mains power cord with an USA plug, chop the middle out of it and solder
the two cut ends to make a shorter mains power cord.

I have already instructed the course organisers who wanted to use this book, the first edition of which I found even more serious errors in such as a circuit that couldn't have worked and didn't.
we modify the book via/using labsheets.
The student is meant to do what we instruct them to do in labsheets the academic writes them I review them and send them changes.

Last year I told them to include a UK plug diagram.
Last year I told them NOT to do the 9V battery on the tongue.
Last year I told them not to extend the lead on a PSU and that I would supply a lengh of two core cable and they would use that.
I told them NOT to do the LED roasting in the last edition they called it broiling.
I told them not to do the lemon experiment as I wasn't willing to pay for or shop for lemons, so the academic brought them in himself and that was totally OK by me.
Last week I told them we do NOT use matrix board or perfboard and that rather than do as the book says we should instruct the students to use stripboard, the academic then altered the labsheet and prodiced a stripboard version.
The book is a guide only I'd perfer us not to spend the money buying books but to write our own.





There is also a chapter on learning how to burn yourself, choke yourself
on fumes from burning insulation and lose any eye from flying debris by
shorting out a battery and waiting for at least two minutes.

Yes and that's why we modify the course with labshhets the stends follow
the book is used as a reference NOT as bloody Bible study !

On Saturday, 12 November 2016 06:02:13 UTC, Rod Speed wrote:
whisky-dave wrote
dennis@home wrote
Dave Plowman (News) wrote
John Rumm wrote

It actually says: "Manufacturers will give lifetime claims in multiples
of 1000 hours. One thousand hours is equivalent to about 6-months use
when the bulb is on for 4 hours per day. A traditional halogen
spotlight
bulb is expected to last about one year (2000 hours) where as an LED
will last between 30,000 and 50,000 hours - that€˜s between 15 and 25
years! Switching to LEDs means you may never have to change your light
bulbs again.",

Heh heh. If the average life of an LED was actually 15 years, why don't
they give them a lifetime warrenty? The number of people who could
produce a receipt after 15 years would be very very small.

If you sold 10 million of them and 0.01% claimed each year
you would need quite a few people to keep up with the claims.
It just wouldn't be economical on the margins they make.

But it doesn;t stop them doing it because they know few will
attempt to claim and those that do you cabn ask have you ever
had them on for more than 4 hours at a time. If they asnwer yes
(which most peolpe will have had) then the warrently is invalid

Wrong. The warranty never says that you can't have them on for longer than 4
hours.

Doesn't say you can't dip them in water.


You have utterly mangled what they do say about 4 hours, as always.

So what does it say.


just as it would be if the do not remove sticker was removed.

Wrong, as always. You still have the warranty if you remove that.

That's the law.

If you don't follow the manufactures rules then you can't claim on the warrenty.
Which are part of teh terms and condition of sales.



One car manufacturer offered lifetime warranties
for a while but they stopped doing it.