Strange problem with low energy light bulb

[Lostgallifreyan]

To run LEDs efficiently from 240V AC will also require some active
electronics. I see no-one ever factors in the power losses that'll be
associated with that.

95% efficient power conversion from 5 to 32V and I think I saw similar
claims for a small module that can power a series chain of LED's from a
mains input. Can't cite a source right now, I just got you one already for
the 176 lumens claim. If I can find the other I'll cite it.

 

[Lostgallifreyan]

[email protected] (GregS) wrote in

Just uses a small CPU fan. I'm actually using a CPU sink/fan combo,
but the LED's are epoxied to a copper plate. I even have diamond dust
as a buffer/insulator. To close space the LED's I needed the best
thermal transfer. Did I forget to mention the Peltier device.

I can see why diamond dust might help, but why a TEC? The LED's can operate
at temperatures great enough to pour heat through a decent thermal coupling
to a heatsink, no need to pump it through by force, that just makes work
for work's sake unless you are forced to drop the temperature in a confined
space, which is doubtful given the size of heatsink you need to dissipate
LED heat + TEC work heat.

 

[Lostgallifreyan]

In any case don't 'white leds' use the same phosphor method of
producing light that CFLs do ?

Higher intensity. Might be nonlinear, as in greater efficiency if you pump
them harder. Might be different materials. I don't know for sure though.

Definitely smaller size, so if you're going to be a stickler for full
context such as analysis of lumens per watt of actual mains input, you must
take all of the context. People have alreay said (rightly) that LED lamps
won't have the trouble that CFL's have in fitting most current luminaries.
That's obviously important regarding watse and expense.

More: LED's are growing more efficient all the time. It might be that in
future these lamps might be directly driven by encapsulated laser diodes
emitting near UV to pump phosphors. Laser diodes have efficiencies beyond
low pressure sodium, they leave it in the dust. It's likely that this
technology will quickly make CFL's look barbarous.

 

[Eeyore]

Eeyore wrote:
Arfa Daily wrote:

With a bit of work, I'm sure that they [LEDs] will
also get to the point where they can replace a standard filament bulb, in
the same sized package, unlike a CFL which has to accommodate the ballast.

To run LEDs efficiently from 240V AC will also require some active electronics.
I see no-one ever factors in the power losses that'll be associated with that.

When you use up the watts, you get heat. The lamp has to efficiently get
rid of it. May even need a fan.

Quite possibly so. How many watts does the fan need ?

I have one here that's 40mm sq. It still uses 1W.

I'm actually using a CPU sink/fan combo, but the LED's are epoxied to a copper
plate. I even have diamond dust as a buffer/insulator. To close space the LED's
I needed the best thermal transfer. Did I forget to mention the Peltier device.
I am also using unmounted LED's.



Nothing is compact. I use a large variable supply.

And the efficiency of that is ?

There is 45 watts going to the LED's.
About 20 [email protected] amps. 3 series sets of LED's. You cannot look at the light.
The device was intended to be flashed in the final form. peaking at about 60 watts.

So how do you control the LED current ? I imagine you may have current sharing issues with parallel chains
too.

What's the AC input watts ?


Graham

 

[Eeyore]

Eeyore wrote


Higher intensity. Might be nonlinear, as in greater efficiency if you pump
them harder. Might be different materials. I don't know for sure though.

Definitely smaller size, so if you're going to be a stickler for full
context such as analysis of lumens per watt of actual mains input, you must
take all of the context. People have alreay said (rightly) that LED lamps
won't have the trouble that CFL's have in fitting most current luminaries.

Well actually I wonder about that. Especially replacements for those 'low
voltage halogen' types like these.
http://www.lightingfx.com/item--Halogen-GU10--51

There's not actually any easy way to lose the heat. The 'enclosure' is very
small.

That's obviously important regarding watse and expense.

More: LED's are growing more efficient all the time. It might be that in
future these lamps might be directly driven by encapsulated laser diodes
emitting near UV to pump phosphors. Laser diodes have efficiencies beyond
low pressure sodium, they leave it in the dust. It's likely that this
technology will quickly make CFL's look barbarous.

I'm not so sure about the quickly bit.

Graham

 

[Lostgallifreyan]

Well actually I wonder about that. Especially replacements for those
'low voltage halogen' types like these.
http://www.lightingfx.com/item--Halogen-GU10--51

There's not actually any easy way to lose the heat. The 'enclosure' is
very small.

No fair! > You try fitting a CFL in there. That's why you're pulling
teeth out of the biting argument in favour of LED's isn't it? Most of the
time in this thread you're advocating CFL's, so this is a spurious issue.

Actually, the Cliften Suspension Bridge in Bristol has its chains entirely
lit by exactly the type of LED-based lamp that replaces little tunsten
halogens. There are three emitters per lamp. The lowest is too high to get
a good look at, but they appear to be Cree or Luxeons in small parabolic
reflectors. Sure, a bridge doesn't have many cooling problems most times,
but those 'chains' are mighty plates of iron, and on summer nights they are
hot. Doesn't stop those lamps working though.

 

[Lostgallifreyan]

Cliften Suspension Bridge

That is so embarrasing I have to correct it. 'Clifton'.

 

[Eeyore]

Eeyore wrote



No fair! > You try fitting a CFL in there. That's why you're pulling
teeth out of the biting argument in favour of LED's isn't it? Most of the
time in this thread you're advocating CFL's, so this is a spurious issue.

To be honest, I'm not actually advocating any specific technology. I am however
very interested on Philips new compact 'CHLi' halogens.
http://www.lighting.philips.com/gl_...main=global&parent=4390&id=gl_en_news&lang=en

I have seen LED 'replacements' for that GU10 type touted, but it's clear they
must have very much lower light output.

Graham

 

[Lostgallifreyan]

To be honest, I'm not actually advocating any specific technology. I
am however very interested on Philips new compact 'CHLi' halogens.
http://www.lighting.philips.com/gl_en/news/press/product_innovations/pr
ess_2006/ecoboost_technology.php?main=global&parent=4390&id=gl_en_news&
lang=en

I'm keen on the developments in halogen lamps too. They have a light
quality I consider second to none. I hope broadband phosphor mixes will be
improved, but they still don't work like a small efficient halogen does.

I need to stop now, want to watch Minder. I need a rest.

 

[GregS]

GregS wrote:
Eeyore wrote:
Arfa Daily wrote:

With a bit of work, I'm sure that they [LEDs] will
also get to the point where they can replace a standard filament bulb, in
the same sized package, unlike a CFL which has to accommodate the ballast.

To run LEDs efficiently from 240V AC will also require some active electronics.
I see no-one ever factors in the power losses that'll be associated with that.

When you use up the watts, you get heat. The lamp has to efficiently get
rid of it. May even need a fan.

Quite possibly so. How many watts does the fan need ?

I have one here that's 40mm sq. It still uses 1W.

I'm actually using a CPU sink/fan combo, but the LED's are epoxied to a copper
plate. I even have diamond dust as a buffer/insulator. To close space the LED's
I needed the best thermal transfer. Did I forget to mention the Peltier device.
I am also using unmounted LED's.



Nothing is compact. I use a large variable supply.

And the efficiency of that is ?

There is 45 watts going to the LED's.
About 20 [email protected] amps. 3 series sets of LED's. You cannot look at the light.
The device was intended to be flashed in the final form. peaking at about 60

watts.

So how do you control the LED current ? I imagine you may have current sharing
issues with parallel chains
too.

What's the AC input watts ?

Not sure, but I am not concerned with efficiency. I am concerned with heat dissapation.
With same batches I have. the individual specs are very close together, so
load distribution is no problem at all. I use a variable voltage/current supply. I
just have to watch to easily move the controls. This is just a test hookup
for now. I am using blue and green colors, they will be strobed to get effects.

A few months ago I bought a batch of cool white 3 watters. I intended to put
some around the house and control them with X10. It
got too complicated with the X10, and I didn't really like the cool white.
The blue LED's are really neat. I have never seen that mystical color temperature
out of LED's before.

 

[Don Klipstein]

message news:[email protected]

My searching finds ordinary 40 watt bulbs rated at from 280 to 355 lumens.
More lumens at a given wattage rating generally means a shorter life. IME
incadescent lights draw significantly less than their rated power, so their
light output may also be less than spec.

280 to 355 lumens is about half the light output of a 11 watt CFL. BTW, my
experience with CFLs pretty well matches the lumen output levels that you've
mentioned, Graham.

In USA, plenty of 40 watt incandescents are rated to produce 445 to 500
lumens. My experience is mostly CFLs consuming 25-30% of the electricity
of "standard" incandescents of same light output.

About twice the brightness from about one quarter the power works for me!

We've seen vastly improved bulb life, which is especially helpful when bulbs
are located where they are hard to replace, such as at the top of a 3-story
stairwell.

My first project was in a large basement room that was frying about one
halogen bulb (of 32) per week, partially due to overheated fixtures. We
pretty much relamped the room almost twice a year. We put in 2 CFL bulbs
per fixture and still dropped the fixture's internal temperature to under
110 degrees F from more like 140. Lumen output per fixture almost tripled.
We were also able to get a more pleasing color temperature. This room is has
been relamped for about 3 years. We are currently replacing about one bulb
per year.

Everyone else who wants to relamp with CFL, watch out with recessed
ceiling fixtures. Strangely nough, CFLs are actually more efficient at
producing heat conducted to the immediately surrounding air than
incandescents are, by producing a lot less infrared. I tried this - a 42
watt CFL heats up a fixture slightly more than a 60 watt incandeswcent
does, at least when I tried it. Make sure your fixture does not get too
hot for the CFL. Not only can excessive heat shorten their lives, but
also excessive heat can make them run dim as well as excessive cold can.

I've done a fair number of fairly large (i.e., 8 or more bulbs per room)
incadescent (mostly halogen) to CFL upgrades, with extremely positive
results. In every case the fixtures were previously loaded up with
incadescent bulbs rated at the fixture's maximum power. They were providing
poor to marginal lighting.

When I can maintain the power usage at a constant level, the results of the
CFL upgrades are brilliant. When I'm forced to run the fixture at reduced
power levels because of bulb space limitations, the results are still
striking and very helpful.

The building in question had lighting engineered to 1950's standards. The
lighting had become ineffective because of rising expectations. Actually
upgrading the fixtures would have been prohibitively expensive.

- Don Klipstein ([email protected])

 

[Don Klipstein]

Issues with LEDs today:

Color rendering
Diffusion

Once those are solved effectively, they will be excellent
alternatives. My guess is 5 years to color rendering, and 5 more to
diffusion. Most LEDs today filter a single color to a specific
monochromatic output.

No, they dopn't filter them - the chips make a specific band of
wavelengths.

Even the LED-type flashlights are very heavily skewed to the blue end of
the spectrum in order to get sufficient brightness,

I just saw some at Target today that appeared to me to have color
temperature around 5500 Kelvin.

and require multiple LEDs to get even a minor beam with
very poor diffusion.

I am talking about ones that have a distinct beam and about as much
light output as a 3-D-cell Mag Light.

Peter Wieck
Wyncote, PA

- Don Klipstein ([email protected])

 

[Don Klipstein]

The length of service issue with LEDs is very dependant on the way they are
driven, if you are to get the maximum of 100,000 hours plus out of them.
However, that said, even if not driven properly - ie not pulsed - from what
I have read, they are still good for 40k hours, before the light output has
dropped by 50%.

White LEDs do better unpulsed. Used as directed, most are rated for
50,000 hours. The main reason for pulsing LEDs nowadays is to dim them in
a linear manner, such as in variable color fixtures and large video
screens. LEDs often have efficiency and color varying when instantaneous
current is changed, and output and color are often specified only at the
"characterizing current". Different color LEDs have different general
trends in how efficiency varies with current.

As far as colour rendering goes, I agree that this can be
achieved with combinations of RGB LEDs, and I'm sure can be made as good or
better now, as CFLs are ( not that I'm saying theat CFLs are good of course
... !) Just a few days ago, I saw somewhere that one of the manufacturers
has come up with LED chips bonded to a sort of 'ball on a stick' shape, so
many small chips face in virtually every direction around a sphere, to get
over the point-source poor beamwidth issue.

BTW, Philips CFLs = China ? Not any more, it would seem. I picked one up in
the supermarket tonight to have a look. It said " Made in Poland " ...

- Don Klipstein ([email protected])

 

[Don Klipstein]

Currently, white LEDs are in fact blue LEDs coated with a fluorescent
substance, so probably the overall light quality will be quite similar
to CFL.

Actually, it's more like that of somewhere between a "cool white" and a
"daylight" old-fashioned fluorescent, with similar color distortions.
There are now some warmer white and higher color rendering index white
LEDs.

- Don Klipstein ([email protected])

 

[Don Klipstein]

The brightest LEDs do unfortunately have that cool blue 7000K or so colour temp.
There's a significant trade off in efficiency for the 3000K ones.

They are now getting color temperature as low as mid 4,000's with no
compromise in light output.

- Don Klipstein ([email protected])

 

[Don Klipstein]

Arfa Daily wrote:

With a bit of work, I'm sure that they [LEDs] will
also get to the point where they can replace a standard filament bulb, in
the same sized package, unlike a CFL which has to accommodate the ballast.

To run LEDs efficiently from 240V AC will also require some active electronics.
I see no-one ever factors in the power losses that'll be associated with that.

When you use up the watts, you get heat. The lamp has to efficiently get
rid of it. May even need a fan.

Quite possibly so. How many watts does the fan need ?

In my experimental 45 watt, 9- 5 watt Luxeon array, I use copper, aluminum, and a fan.
DC drive is nice.

The normal home doesn't have DC. What do you use for current limiting
and how much power does that dissipate ?

Electronic ballasts for fluorescent lamps (including the ones in all
spiral and most other screw base CFLs) require DC, so require conversion
of AC to DC, and for that matter back to AC of a higher frequency. Many
of those don't have huge losses, in fact usually less loss than iron core
inductive ballasts.

- Don Klipstein ([email protected])

 

[Don Klipstein]

http://www.lumileds.com/products/line.cfm?lineId=19

145 Typical lumens from 700mA @ 3.6V, or 58 lumens per watt. The LED is
a surface mount chip 3.1 x 4.6 x 2.1 millimeters in size. A thin strip
of 12 of these chips puts out light comparable to a 100W tungsten lamp
but only uses 30W.

145 typical lumens at junction temperature 25 degrees C for the highest
brightness rank in the datasheet. Now, what about with a heatsink
temperature of 35 degrees C and for the highest brightness rank in the
Future Electronics website?

30 watts into these means probably about 25 watts of heat. Hmmm, what
if you mount a dozen of those onto a heatsink the size of the tip and
heating element combined of a 25 watt soldering iron? What would the
heatsink temperature reach then? What does the datasheet say performance
is at that temperature?

With a good size heatsink to stay at a comfortable temperature with 25
watts, I don't see it looking like a universal incandescent or CFL
replacement just yet.

I'm using 8 of the older Luxeon K2 LEDs in a bicycle light. The output
is nothing short of impressive. It's brilliant at just 5W of input
power. Crank it up to 40W and it puts car headlights to shame.

That I believe!

- Don Klipstein ([email protected])

 

[Don Klipstein]

The colour temperature won't be anywhere near comparable.

In any case don't 'white leds' use the same phosphor method of producing light
that CFLs do ?

No, they use a different phosphor made for LEDs. Color rendering of
white LEDs is more like that of "old tech" halophoaphate fluorescents than
like that of CFLs. At least the color rendering index is somewhat better
than that of "old tech cool white".

- Don Klipstein ([email protected])

 

[Don Klipstein]

Higher intensity. Might be nonlinear, as in greater efficiency if you pump
them harder. Might be different materials. I don't know for sure though.

White LEDs are nonlinear, generally with efficiency maximized at some
fraction of rated power.

Definitely smaller size, so if you're going to be a stickler for full
context such as analysis of lumens per watt of actual mains input, you must
take all of the context. People have alreay said (rightly) that LED lamps
won't have the trouble that CFL's have in fitting most current luminaries.
That's obviously important regarding watse and expense.

When an LED or an LED cluster has to dissipate 20 watts of heat, it will
probably have to be bigger than a CFL of same power input.

More: LED's are growing more efficient all the time. It might be that in
future these lamps might be directly driven by encapsulated laser diodes
emitting near UV to pump phosphors. Laser diodes have efficiencies beyond
low pressure sodium, they leave it in the dust.

There are some high power IR laser diodes more efficienct than LPS.
Other than those, laser diodes are less efficient than most sodium lamps.

Phosphors have a loss. I expect the ultimate in LED efficiency in the
future will have at least some of the light being the radiation produced
by the LED chips, rather than by phosphors.

- Don Klipstein ([email protected])

 

[Arfa Daily]

Eeyore wrote:
GregS wrote:
Eeyore wrote:
Arfa Daily wrote:

With a bit of work, I'm sure that they [LEDs] will
also get to the point where they can replace a standard filament
bulb, in
the same sized package, unlike a CFL which has to accommodate the ballast.

To run LEDs efficiently from 240V AC will also require some active electronics.
I see no-one ever factors in the power losses that'll be associated
with that.

When you use up the watts, you get heat. The lamp has to efficiently
get
rid of it. May even need a fan.

Quite possibly so. How many watts does the fan need ?

I have one here that's 40mm sq. It still uses 1W.

I'm actually using a CPU sink/fan combo, but the LED's are epoxied to a copper
plate. I even have diamond dust as a buffer/insulator. To close space
the LED's
I needed the best thermal transfer. Did I forget to mention the Peltier device.
I am also using unmounted LED's.


In my experimental 45 watt, 9- 5 watt Luxeon array, I use copper, aluminum,
and a fan. DC drive is nice.

The normal home doesn't have DC. What do you use for current limiting
and how
much power does that dissipate ?

Nothing is compact. I use a large variable supply.

And the efficiency of that is ?

There is 45 watts going to the LED's.
About 20 [email protected] amps. 3 series sets of LED's. You cannot look at the light.
The device was intended to be flashed in the final form. peaking at
about 60

watts.

So how do you control the LED current ? I imagine you may have current
sharing
issues with parallel chains
too.

What's the AC input watts ?

Not sure, but I am not concerned with efficiency. I am concerned with heat
dissapation.
With same batches I have. the individual specs are very close together, so
load distribution is no problem at all. I use a variable voltage/current
supply. I
just have to watch to easily move the controls. This is just a test hookup
for now. I am using blue and green colors, they will be strobed to get
effects.

A few months ago I bought a batch of cool white 3 watters. I intended to
put
some around the house and control them with X10. It
got too complicated with the X10, and I didn't really like the cool white.
The blue LED's are really neat. I have never seen that mystical color
temperature
out of LED's before.

They are changing over the emergency vehicle beacons here in the UK now to
blue LEDs, and as you say, the colour is such a brilliantly intense blue,
that they are far more visible as being emergency vehicles over a much
greater distance, than ever the blue plastic-filtered zenon flashes were.

Arfa