From: Don K on
"Don Klipstein" <don(a)manx.misty.com> wrote in message news:slrnes2r0d.i7d.don(a)manx.misty.com...
>
> It's going to be a while and the advance of LEDs is going to be slow.
> And the main obstacles now for LEDs are cost reduction. Available now
> only in recent months are white LEDs with efficiency getting into the
> fluorescent range, with such efficiency at about 1.2 watts per LED with
> these LEDs in quantities of thousands costing more than I pay for 4-foot
> fluorescents at home centers.
>
> The latest announced laboratory prototype for high efficiency white LEDs
> already has about half the efficiency of a white LED based on a phosphor
> with 100% quantum efficiency coated onto a 100% efficient blue LED chip.
> I see the top efficiency level of efficiency of the laboratory prototypes
> already getting into a plateau, while at that level only about 50% above
> the efficiency of some very common fluorescent bulbs in common real-world
> use.
>

About 15 years ago, one of the guys in my lab was working on a project developing
prototypes for self-contained RF plasma lightbulbs. I don't know the power,
but it was certainly under a hundred Watts, but those things put out the
most intense light I ever saw. Apparently they're a lot more efficient than
your typical flourescent bulb. They ended up using them to light up a museum.

Don


From: Don Klipstein on
In article <1170306957.709652.325980(a)a75g2000cwd.googlegroups.com>, Ron
Peterson wrote:
>On Jan 31, 10:14 pm, d...(a)manx.misty.com (Don Klipstein) wrote:
>> In <srhi-DFD342.09111931012...(a)newsgroups.comcast.net>, Shawn Hirn wrote:
>
>> Keep in mind that a 1.2 watt LED costs more than a 4-foot fluorescent
>> bulb, and I have yet to hear of LEDs other than laboratory prototypes
>> producing more lumens per watt (at full power) than commonly available
>> F32T8 4-foot fluorescents.
>
>That's true for white LEDs which use flourescent material, but
>monochrome LEDs can be more efficient on a lumens per watt basis for
>applications like stop lights.

Lumens per watt for colored LEDs exceeding that of the best white
production units that I have already gotten into my grubby mitts?

What? By who? Where and how to get? I don't believe it. For that
matter, best lumens out per watt in is more for white than for any
spectral color for announced laboratory prototypes also as far as I have
heard.

I know a way to get yellow and yellowish-green to improve a little over
the best white ones by means of adding fluorescent materials (to white or
to just their underlying blue chips), but for some reason I have yet to
see a press release in that area.

The big efficiency advantage of LEDs in traffic signals is over the
really lousy efficiency of superlonglife vibration resistant incandescents
that have some, mainly most, of their light blocked by colored filters.

- Don Klipstein (don(a)misty.com)
From: Don Klipstein on
In article <E_mdnd8xvMOx51zYnZ2dnUVZ_qOpnZ2d(a)comcast.com>, Don K wrote:
>"Don Klipstein" <don(a)manx.misty.com> wrote in message
news:slrnes2r0d.i7d.don(a)manx.misty.com...
>>
>> It's going to be a while and the advance of LEDs is going to be slow.
>> And the main obstacles now for LEDs are cost reduction. Available now
>> only in recent months are white LEDs with efficiency getting into the
>> fluorescent range, with such efficiency at about 1.2 watts per LED with
>> these LEDs in quantities of thousands costing more than I pay for 4-foot
>> fluorescents at home centers.
>>
>> The latest announced laboratory prototype for high efficiency white LEDs
>> already has about half the efficiency of a white LED based on a phosphor
>> with 100% quantum efficiency coated onto a 100% efficient blue LED chip.
>> I see the top efficiency level of efficiency of the laboratory prototypes
>> already getting into a plateau, while at that level only about 50% above
>> the efficiency of some very common fluorescent bulbs in common real-world
>> use.
>>
>
>About 15 years ago, one of the guys in my lab was working on a project developing
>prototypes for self-contained RF plasma lightbulbs. I don't know the power,
>but it was certainly under a hundred Watts, but those things put out the
>most intense light I ever saw. Apparently they're a lot more efficient than
>your typical flourescent bulb. They ended up using them to light up a museum.
>
>Don

You may be talking about sulfur lamps. They gained some press in the
mid-late 1990's, with efficiency in the sodium lamp range and life
expectancy really way up there.

The big problem with those is that their ballasts are magnetrons, with
efficiency maybe 70% or so and life expectancy in the lower 5 figures,
comparable to that of fluorescent bulbs.

The ones deemed most practical were a lot more than a hundred watts,
closer to a kilowatt.

- Don Klipstein (don(a)misty.com)
From: Don K on
"Don Klipstein" <don(a)manx.misty.com> wrote in message news:slrnes305l.3qd.don(a)manx.misty.com...
> In article <E_mdnd8xvMOx51zYnZ2dnUVZ_qOpnZ2d(a)comcast.com>, Don K wrote:
>>
>>About 15 years ago, one of the guys in my lab was working on a project developing
>>prototypes for self-contained RF plasma lightbulbs. I don't know the power,
>>but it was certainly under a hundred Watts, but those things put out the
>>most intense light I ever saw. Apparently they're a lot more efficient than
>>your typical flourescent bulb. They ended up using them to light up a museum.
>>
>>Don
>
> You may be talking about sulfur lamps. They gained some press in the
> mid-late 1990's, with efficiency in the sodium lamp range and life
> expectancy really way up there.
>
> The big problem with those is that their ballasts are magnetrons, with
> efficiency maybe 70% or so and life expectancy in the lower 5 figures,
> comparable to that of fluorescent bulbs.
>
> The ones deemed most practical were a lot more than a hundred watts,
> closer to a kilowatt.
>

Possibly sulfur, I wasn't paying much attention, other than it was annoying
the way he'd light up the whole lab when testing it. ;-)

No magnetron, he was generating a plasma with a much lower RF frequency. IIRC he
was using a silicon carbide transistor as an RF source and most of the effort was
to efficiently match impedances for efficiency. The thing was in the shape of
a regular lightbulb.

Don


From: Chris Malcolm on
throwitout(a)dodgeit.com wrote:
> On Jan 30, 6:08 pm, BeaFor...(a)msn.com wrote:

>> I have changed all my light bulbs to flouresent and the savings was
>> considerable, until the utility company raised rates. Now I am
>> starting
>> to see LED bulbs. Seem kind of spendy. Anyone have experience with
>> them?

> Won't see them replacing your household lights anytime soon.
> Efficiency is about the same or worse than Florescent. I've yet to see
> one match the light output of a normal light

Their killer savings area is in flashlights, whose requirement for a
small focussable light source rules out fluorescents. They save a
great deal on battery power. A high power white LED flashlight running
of AAs can now outperform a big incandescent flashlight running of D
cells. The impact this has had on my domestic lighting is that we now
use torches for a lot more things, such as going to the toilet in the
middle of the night, instead of firing up half a dozen big mains
powered lights for several minutes, or even leaving the hall light on
all night "just in case".

--
Chris Malcolm cam(a)infirmatics.ed.ac.uk DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]