Others in the room who work on the design of LED drivers made a number
of arguments to explain why 90% is indeed a challenge for this
application. The only significant issue, in my opinion, is the
challenge of driving a low voltage DC load. Certainly a driver
designed for a single LED could have substantial output rectifier
losses, but if LEDs are connected in series to raise the load voltage,
the additional losses related to creating DC should be negligible. Of
course, the low voltage incandescent lamp does not require DC.

No output rectifier losses, no losses in the input capacitor -
especially as it ages, no losses in the output capacitor, no losses in
snubber networks.

In message <8cp5u2tceq5m9e29guc5macfmlla68f1ve@4ax.com>, Victor Roberts
xxx@lighting-research.com> writes
Others in the room who work on the design of LED drivers made a number
of arguments to explain why 90% is indeed a challenge for this
application. The only significant issue, in my opinion, is the
challenge of driving a low voltage DC load. Certainly a driver
designed for a single LED could have substantial output rectifier
losses, but if LEDs are connected in series to raise the load voltage,
the additional losses related to creating DC should be negligible. Of
course, the low voltage incandescent lamp does not require DC.

Current LED lamps that use arrays of 5mm devices tend to use a
capacitive dropper and rectifier arrangement with the only real loss
incurred by the series inrush current limiting resistor. That actually
makes the circuit quite efficient even if the current/voltage waveform
is less than desirable looking to the supply authorities.

A quick reminder of what's inside a cheap LED lamp....

http://www.emanator.demon.co.uk/candle2.jpg

Victor Roberts wrote:
The first is IR reflecting films, a technology that is
already in commercial use. Considering that 90% to 95% of
the energy generated by an incandescent filament is radiated
away as IR (depending upon where you define the long
wavelength end of the visible spectrum), using IR films to
raise the efficacy of incandescent lamps by a factor of 3 or
even 4 is possible. Low-voltage IR-halogen filament tubes
may already meet the initial goal of 30 lm/W. (Most
IR-halogen lamps are reflector lamps so I don't have ready
access to data on bare filament tubes, but this is what we
suspect Osram is doing with their e-Pro lamp.)

FWIW, Osram in Europe do sell an IR halogen capsule under the name of
Halostar IRC. I don't have a catalogue to hand so I can't quote
efficacies, but IIRC their 35W version has approximately the output of
their standard 50W.

It's worth getting one and doing a comparison, however. I use their
IR-coated MR16s all the time, but when I looked at the AR111 versions, I
found that the light from the IRC versions was a warmer colour (the
opposite of what you'd expect?!) and thus to the eye rather than the
light meter it actually looked dimmer than the non-IR version...

Yesterday I read a press release from GE stating that they
were working on new technology that could eventually make
incandescent lamps as efficient as CFLs. The short term
goal is 30 lm/W. I can't find a copy of that press release
at the moment, but it does raise some interesting questions.

I have not had any connection with GE incandescent lamp
technology since I retired in late 1999. There were two
publicly-known technologies they were working on at the time
that, if improved, could raise the efficacy of incandescent
lamps to the 50 to 60 lm/W range.

The first is IR reflecting films, a technology that is
already in commercial use. Considering that 90% to 95% of
the energy generated by an incandescent filament is radiated
away as IR (depending upon where you define the long
wavelength end of the visible spectrum), using IR films to
raise the efficacy of incandescent lamps by a factor of 3 or
even 4 is possible. Low-voltage IR-halogen filament tubes
may already meet the initial goal of 30 lm/W. (Most
IR-halogen lamps are reflector lamps so I don't have ready
access to data on bare filament tubes, but this is what we
suspect Osram is doing with their e-Pro lamp.)

The second technology area is selective emitters. These can
be tungsten that has light-wavelength-sized patterns that
reduce emission of IR radiation while not reducing visible
emission, or they can be materials that are inherently
selective emitters. The prospect for these lamps was raised
by John Waymouth at LS:5 in York, UK in 1989. Research at
the old Bell Labs and more recently at GE R&D has shown that
it is possible to produce an efficacy gain through use of
patterned tungsten or alternate selective-emitting
materials. However, to the best of my knowledge, no one
has been able to develop a system that maintains this
efficacy gain for more then a few hundred hours at the
temperatures required for efficiency light generation.

This should be an interesting area to follow. Perhaps there
will be more information at Light Fair.

Looks like a beauty. I certainly haven't come across one such. Looks like it's
electronically ballasted.

But is it really that bad that you start seeing significant lumen depreciation
during its lifetime?

OSRAM makes several kinds of small metal halides, (the HQI-TS/WDL) around 75W,
and they have installed dozens of them outside my house on the sidewalk. I
haven't noticed any depreciation in their 3-4 years of service, but some have
started cycling and some have extremely shifted colors.

Perhaps the electronic components in your specimen are to blame?

On a somewhat related note. A local movie complex recently replaced
the halogen PAR38 lamps in its main lobby and hallways with CFL PARs.
As it turns out, I happened to visit this complex just before and after
this relamping and was shocked by my reaction. What was once a warm,
friendly and visually inviting place took on a dreary, almost lifeless
quality, and while I fully applaud the move to a more energy efficient
and environmentally friendly technology, I very much dislike its impact
on the general atmosphere (and these are good quality lamps with a CRI
of 86). This is one of the reasons why this announcement has caught my
interest -- a halogen lamp that operates at the same efficiency as a
CFL would provide us with all the warmth and charm of incandescent
lighting without any of the guilt and shame.

On a somewhat related note. A local movie complex recently replaced
the halogen PAR38 lamps in its main lobby and hallways with CFL PARs.
As it turns out, I happened to visit this complex just before and
after this relamping and was shocked by my reaction. What was once a
warm, friendly and visually inviting place took on a dreary, almost
lifeless quality, and while I fully applaud the move to a more energy
efficient and environmentally friendly technology, I very much dislike
its impact on the general atmosphere (and these are good quality lamps
with a CRI of 86). This is one of the reasons why this announcement
has caught my interest -- a halogen lamp that operates at the same
efficiency as a CFL would provide us with all the warmth and charm of
incandescent lighting without any of the guilt and shame.

There are certain venues where it's better to keep tungsten for colour
rendering and use the CFL's as fill lights in less visually critical
areas. The entertainment and food industries come to mind.

I suspect they used the wrong color temperature and perhaps
increased the light level. Another case where bad design
has perhaps lead to making many people believe that CFLs
cannot replace incandescent lamps.

With the help of a qualified lighting designer they should
have been able to find CFLs which would have provided the
same atmosphere. (Perhaps customers also need to convince
the industry to make lower CCT CFLs to match low power
incandescent lamp applications.)

Paul M. Eldridge wrote:

A local movie complex recently replaced
the halogen PAR38 lamps in its main lobby and hallways with CFL PARs.
What was once a
warm, friendly and visually inviting place took on a dreary, almost
lifeless quality, and [...] these are good quality lamps
with a CRI of 86. [...] a halogen lamp at the same
efficiency as a CFL would provide us with all the warmth and charm of
incandescent lighting without any of the guilt and shame.

I suspect they used the wrong color temperature and perhaps
increased the light level. Another case where bad design
has perhaps lead to making many people believe that CFLs
cannot replace incandescent lamps.

With the help of a qualified lighting designer they should
have been able to find CFLs which would have provided the
same atmosphere. (Perhaps customers also need to convince
the industry to make lower CCT CFLs to match low power
incandescent lamp applications.)

My favorite example of a bad technology-based law is the one
giving preferences to hybrid vehicles - such as preference
in HOV lanes on US highways. I have a non-hybrid Passat
that gets better highway mileage than some hybrids. Any
hybrid car is allowed in the HOV lane with only one
passenger and I my Passat is not.

The regulations that many say banned EM ballasts in the US
never mention EM ballasts or any other ballast technology.
They just call for a level of performance that is almost
impossible to meet with EM ballasts. That's the way the
lighting regulations should be written. The regulations
should not specify CFLs or LEDs, they should specify
efficacy - under real operating conditions, of course.

I agree with your general point, but I would argue one difference.
The issue of lamps is all about providing incentive for efficiency,
full stop. There is an advantage to incandescents over CFLs in that
they don't contain mercury,

In article <1172953476.614771.326520@h3g2000cwc.googlegroups.com>,
"Thomas Paterson" <t_p_paterson@hotmail.com> writes:
I agree with your general point, but I would argue one difference.
The issue of lamps is all about providing incentive for efficiency,
full stop.There is an advantage to incandescents over CFLs in that
they don't contain mercury,

Burning fossel fuel to power them releases more mercury into
the air than an equivalent CFL contains.

In article <1172953476.614771.326...@h3g2000cwc.googlegroups.com>,
"Thomas Paterson" <t_p_pater...@hotmail.com> writes:

I agree with your general point, but I would argue one difference.
The issue of lamps is all about providing incentive for efficiency,
full stop. There is an advantage to incandescents over CFLs in that
they don't contain mercury,

Burning fossel fuel to power them releases more mercury into
the air than an equivalent CFL contains.