Lux Rebel has issues........

[Crescentius Vespasianus]

For those of you who are waiting for the
Lux rebel (200 lumans) rollout in LED
lights, they are having some problems
with them. Here's a thread I found on it.
---------
I think you are giving the Lumiled
morons way too much credit.

First they take the time to push the
state of the art up to new highs in
lumens/watt then package the Rebel in
this CRAPPY little poorly designed
asymmetric package.

The heat pad, that everyone is so
worried about is not only TINY, it
doesn't even cover the area that it
could on the bottom of the package! Gee,
that seems pretty stupid, doesn't it?

The electrical connection pads are also
quite TINY considering the 700mA to 1A
of current that you could be pushing
through them. This is made worse by the
fact that surface mount devices somtimes
get placed a little off center, which
would further reduce the contact area.
Also, they are all the way over at the
end of their cockeyed asymmetric
package, with only these skinny little
conductor tracks along the top of the
package to connect to the die. At a time
when others are adding additional bond
wires to lower Vf, why increase the
package resistance unnecessarily in this
way? STUPID AGAIN!

I can't think of a single reason for
cockeyed little asymetric package (other
than the fact that it's cheap to
produce), unless the Lumiled folks,
aware that CREE, and Soeul will be hot
on their heels with higher output chips,
figured that they would get clever and
come up with this tiny little package
that can be 'clustered' (so even if you
can't push any more lumens out of the
poor little rebel chip, you can just buy
three or four and jam them together in a
kind of Lumiled Cluster-F...).

A square or only slightly rectangular
package with about 20% more width than
the current rebel's narrowest dimension,
and with the emitter CENTERED and
contacts at the ends would be at least
as good thermally, and MUCH better for
most LED flashlight applications, which
use a SINGLE LED and where you have to
fit the emitter up inside existing
reflector designs.

For those who do need to 'cluster' the
rebel chips, or who already have
automated production set up for the
current design, Lumiled should obviously
continue to offer them, but with many
IC's and other semiconductor devices
already available in multiple package
types, I look forward to seeing the
Rebel LED die offered in a more
intelligently designed package.

So, for the record; I have worked with
the Rebels; Love the performance, HATE
the packageing.
========
i can think of a reason, because its not
designed for a flashlight, it has a
higher purpose in mind, one that doesnt
use 1 light PER unit ?
that fits behind LCD screens and takes
100+ of them? that gets adopted into
some manufactured products ? that can go
into $4000 overpriced HDTVs? and it
takes 400 of them? that goes into some
goverment project, that breaks down
after 4 uses.? would you believe jumbotrons?
========
A LCD screen that uses 100 plus - 100
Lumen LED's . . .

I want one!

Of course you might have to view this
10,000 lumen monster using welding
goggles, but that's a small price to pay
to be on the cutting edge.

[Phil]

Crescentius Vespasianus wrote:
> For those of you who are waiting for the
> Lux rebel (200 lumans) rollout in LED
> lights, they are having some problems
> with them. Here's a thread I found on it.

It was obvious from the start that the design was flawed. The Cree and
Seoul Semiconductor still embarrass the Luxeons. One advantage the Rebel
has is that it can use existing reflectors designed for older generation
LEDs. One has to actually worry about blinding oncoming traffic with these
new LEDs.

Still, very few people know about these new LEDs. Some people are amazed
with old 5mm LEDs in terms of total output. Don't get me wrong, the 5mm's
are very efficient at lower currents, but they can't handle the power.

--
Phil

[fart bell]

"Crescentius Vespasianus" <jazzyboss@hotmail.com> wrote in message
news:13cfenqjhs659db@corp.supernews.com...
> For those of you who are waiting for the

return of Clem Schnide!

[Kevin McMurtrie]

A little less of the Luxeon product line is vaporware. I received my
Rebels to play with - four LXML-PWC1-0040 as test subjects and ten
LXML-PWC1-0090 for the real project. They're rather pricey so that's
all I'm buying for now.

The web site really doesn't give you an idea of how tiny these LEDs are.
They are an extremely intense point of light that actually stings your
finger like sunshine from a magnifying glass. They're crazy bright.

The K2 heatsink was a disaster so I was a bit skeptical about the odd
Rebel heatsink. I was pleasantly surprised to find that it works very
well. You solder it to copper and the LED stays cool even when
overdriven to 1A.

I abused a 0040 by soldering it to a 1x1x.125 inch copper tab and
driving it at 1A. After working well for a while it dimmed and
unsoldered itself. It worked again when it cooled.

The quality of the Rebel seems to be higher than the K2. I ordered
about 30 K2s for projects and all were extremely off electrical spec and
some had bubbles in the lenses. So far the Rebels meet their electrical
specs and seem to be free of defects. Forward voltage is very stable
and consistent.

I used the 0040 LEDs to experiment with hobbyist soldering options. I'd
love to solder these to a thin film PCB and glue that to an aluminum
heatsink but I can't find thin film PCBs for public sale :( You can't
simply solder these to the edge of a copper bar because they'll float
away as soon as the solder melts. I found two options that work. You
can drill 4 small holes in the heatsink around the thermal pad contact
area. Excess solder flows into these holes and surface tension centers
the LED. Another option is a tiny dab of silicone glue on the exposed
ceramic area. Hang the power tabs over the edge of the heatsink so you
can solder on wires.

The tiny size of the Rebel begs for them to be built into ultra-compact
flashlights. I wouldn't think of them as 3W LEDs because they're too
inefficient at that point. If you have that much room for a heatsink
then you might as well use bigger LEDs. Think of them as 1W LEDs that
can be momentarily driven to 3.5W when you need an emergency boost.

So the project now -

I'm using a switching regulator based on the LM2679 and a Zetex current
sensor chip to drive 10 LXML-PWC1-0090 Rebels into 18mm lenses. The
idea is that the tiny size of the Rebel lets me run many LEDs at an
efficient current rather than a few large LEDs at an inefficient
current. My goal is 1W to 10W for normal operation and momentary
capability to 40W. Dimming will use voltage feedback at low power and
current feedback at high power. I got a prototype power supply running
very well before I dropped it and bent $50 in surface mount power
components. All the copper parts are cut for the real thing. I still
need a few electrical parts and a thermally conductive body. Carbon
fiber with a pyrolytic graphite sheet liner might do the trick. The
final size should be around 6x2.5x1.5 inches. Input power will be 9V to
40V DC.

Until this project is done, my K2 (LXK2-PW14-U00) bike light works quite
well. The new project is half for fun and half to create a light that
can be hand-held too.

[Crescentius Vespasianus]

> It was obvious from the start that the design was flawed. The Cree and
> Seoul Semiconductor still embarrass the Luxeons. One advantage the Rebel
> has is that it can use existing reflectors designed for older generation
> LEDs. One has to actually worry about blinding oncoming traffic with these
> new LEDs.
>
> Still, very few people know about these new LEDs. Some people are amazed
> with old 5mm LEDs in terms of total output. Don't get me wrong, the 5mm's
> are very efficient at lower currents, but they can't handle the power.
========
If they put these new generation LED's
into bike lights, they might have to set
them up with a high beam and a low beam,
or they will blind on coming traffic. I
just wish the bike light people,
especially cateye would get with the
current technology, their stuff is
really old, and not much light. I guess
I might just buy one of these
flashlights and buy that twofish
flashlight mount, and go that route. I
know for a fact that would be much
cheaper.

[Phil]

Crescentius Vespasianus wrote:
>> It was obvious from the start that the design was flawed. The Cree
>> and Seoul Semiconductor still embarrass the Luxeons. One advantage
>> the Rebel has is that it can use existing reflectors designed for
>> older generation LEDs. One has to actually worry about blinding
>> oncoming traffic with these new LEDs.
>>
>> Still, very few people know about these new LEDs. Some people are
>> amazed with old 5mm LEDs in terms of total output. Don't get me
>> wrong, the 5mm's are very efficient at lower currents, but they
>> can't handle the power.
> ========
> If they put these new generation LED's
> into bike lights, they might have to set
> them up with a high beam and a low beam,
> or they will blind on coming traffic. I
> just wish the bike light people,
> especially cateye would get with the
> current technology, their stuff is
> really old, and not much light. I guess
> I might just buy one of these
> flashlights and buy that twofish
> flashlight mount, and go that route. I
> know for a fact that would be much
> cheaper.

I highly recommend the Fenix L2D. It outclasses the $300-$500 units on a
simple 2AA with a regulated current circuit. $50 each.

--
Phil

[Crescentius Vespasianus]

Phil wrote:
> Crescentius Vespasianus wrote:
>>> It was obvious from the start that the design was flawed. The Cree
>>> and Seoul Semiconductor still embarrass the Luxeons. One advantage
>>> the Rebel has is that it can use existing reflectors designed for
>>> older generation LEDs. One has to actually worry about blinding
>>> oncoming traffic with these new LEDs.
>>>
>>> Still, very few people know about these new LEDs. Some people are
>>> amazed with old 5mm LEDs in terms of total output. Don't get me
>>> wrong, the 5mm's are very efficient at lower currents, but they
>>> can't handle the power.
>> ========
>> If they put these new generation LED's
>> into bike lights, they might have to set
>> them up with a high beam and a low beam,
>> or they will blind on coming traffic. I
>> just wish the bike light people,
>> especially cateye would get with the
>> current technology, their stuff is
>> really old, and not much light. I guess
>> I might just buy one of these
>> flashlights and buy that twofish
>> flashlight mount, and go that route. I
>> know for a fact that would be much
>> cheaper.
>
> I highly recommend the Fenix L2D. It outclasses the $300-$500 units on a
> simple 2AA with a regulated current circuit. $50 each.
>
I was thinking about getting that, some
questions though.
1. Do you use the twofish mount, and if
so, does it work well?
2. How is the throw, can you get spot
out there, or does it just flood in
front of the wheel?
3. I assume you have the Cree, the CR-E
Led. Is it hard to switch on and off
while riding?

[Donga]

On Aug 25, 2:19 am, Crescentius Vespasianus <jazzyb...@hotmail.com>
wrote:
> Phil wrote:
> > Crescentius Vespasianus wrote:
> >>> It was obvious from the start that the design was flawed. The Cree
> >>> and Seoul Semiconductor still embarrass the Luxeons. One advantage
> >>> the Rebel has is that it can use existing reflectors designed for
> >>> older generation LEDs. One has to actually worry about blinding
> >>> oncoming traffic with these new LEDs.
>
> >>> Still, very few people know about these new LEDs. Some people are
> >>> amazed with old 5mm LEDs in terms of total output. Don't get me
> >>> wrong, the 5mm's are very efficient at lower currents, but they
> >>> can't handle the power.
> >> ========
> >> If they put these new generation LED's
> >> into bike lights, they might have to set
> >> them up with a high beam and a low beam,
> >> or they will blind on coming traffic. I
> >> just wish the bike light people,
> >> especially cateye would get with the
> >> current technology, their stuff is
> >> really old, and not much light. I guess
> >> I might just buy one of these
> >> flashlights and buy that twofish
> >> flashlight mount, and go that route. I
> >> know for a fact that would be much
> >> cheaper.
>
> > I highly recommend the Fenix L2D. It outclasses the $300-$500 units on a
> > simple 2AA with a regulated current circuit. $50 each.
>
> I was thinking about getting that, some
> questions though.
> 1. Do you use the twofish mount, and if
> so, does it work well?
> 2. How is the throw, can you get spot
> out there, or does it just flood in
> front of the wheel?
> 3. I assume you have the Cree, the CR-E
> Led. Is it hard to switch on and off
> while riding?

I recently picked up some Ay Up lights, with Luxeon LEDs. They are
just changing over to the Cree CREs and have offered existing
customers a cheap upgrade. It will be interesting to compare them,
when they arrive. In my shopping, it seemed like a nice product at a
good price, and has turned out that way. www.ayup.com.au

Donga

[Phil]

Crescentius Vespasianus wrote:
> Phil wrote:
>> Crescentius Vespasianus wrote:
>>>> It was obvious from the start that the design was flawed. The Cree
>>>> and Seoul Semiconductor still embarrass the Luxeons. One advantage
>>>> the Rebel has is that it can use existing reflectors designed for
>>>> older generation LEDs. One has to actually worry about blinding
>>>> oncoming traffic with these new LEDs.
>>>>
>>>> Still, very few people know about these new LEDs. Some people are
>>>> amazed with old 5mm LEDs in terms of total output. Don't get me
>>>> wrong, the 5mm's are very efficient at lower currents, but they
>>>> can't handle the power.
>>> ========
>>> If they put these new generation LED's
>>> into bike lights, they might have to set
>>> them up with a high beam and a low beam,
>>> or they will blind on coming traffic. I
>>> just wish the bike light people,
>>> especially cateye would get with the
>>> current technology, their stuff is
>>> really old, and not much light. I guess
>>> I might just buy one of these
>>> flashlights and buy that twofish
>>> flashlight mount, and go that route. I
>>> know for a fact that would be much
>>> cheaper.
>>
>> I highly recommend the Fenix L2D. It outclasses the $300-$500 units
>> on a simple 2AA with a regulated current circuit. $50 each.
>>
> I was thinking about getting that, some
> questions though.
> 1. Do you use the twofish mount, and if
> so, does it work well?

I think I have one but never used it. Looks pretty robust.

> 2. How is the throw, can you get spot
> out there, or does it just flood in
> front of the wheel?

Flood with a good spot. Nonadjustable.

> 3. I assume you have the Cree, the CR-E
> Led. Is it hard to switch on and off
> while riding?

Push-button, not hard at all.

Check out the headlamp Princeton Tec EOS Cree/Seoul mod. I use it for night
riding in dark areas.


--
Phil

[Donga]

On Aug 25, 10:46 am, Donga <idomybestworkonab...@hotmail.com> wrote:
> On Aug 25, 2:19 am, Crescentius Vespasianus <jazzyb...@hotmail.com>
> wrote:
>
>
>
> > Phil wrote:
> > > Crescentius Vespasianus wrote:
> > >>> It was obvious from the start that the design was flawed. The Cree
> > >>> and Seoul Semiconductor still embarrass the Luxeons. One advantage
> > >>> the Rebel has is that it can use existing reflectors designed for
> > >>> older generation LEDs. One has to actually worry about blinding
> > >>> oncoming traffic with these new LEDs.
>
> > >>> Still, very few people know about these new LEDs. Some people are
> > >>> amazed with old 5mm LEDs in terms of total output. Don't get me
> > >>> wrong, the 5mm's are very efficient at lower currents, but they
> > >>> can't handle the power.
> > >> ========
> > >> If they put these new generation LED's
> > >> into bike lights, they might have to set
> > >> them up with a high beam and a low beam,
> > >> or they will blind on coming traffic. I
> > >> just wish the bike light people,
> > >> especially cateye would get with the
> > >> current technology, their stuff is
> > >> really old, and not much light. I guess
> > >> I might just buy one of these
> > >> flashlights and buy that twofish
> > >> flashlight mount, and go that route. I
> > >> know for a fact that would be much
> > >> cheaper.
>
> > > I highly recommend the Fenix L2D. It outclasses the $300-$500 units on a
> > > simple 2AA with a regulated current circuit. $50 each.
>
> > I was thinking about getting that, some
> > questions though.
> > 1. Do you use the twofish mount, and if
> > so, does it work well?
> > 2. How is the throw, can you get spot
> > out there, or does it just flood in
> > front of the wheel?
> > 3. I assume you have the Cree, the CR-E
> > Led. Is it hard to switch on and off
> > while riding?
>
> I recently picked up some Ay Up lights, with Luxeon LEDs. They are
> just changing over to the Cree CREs and have offered existing
> customers a cheap upgrade. It will be interesting to compare them,
> when they arrive. In my shopping, it seemed like a nice product at a
> good price, and has turned out that way.www.ayup.com.au
>
> Donga

That was XREs, sorry.

[Phil]

Kevin McMurtrie wrote:
>A little less of the Luxeon product line is vaporware. I received my
> Rebels to play with - four LXML-PWC1-0040 as test subjects and ten
> LXML-PWC1-0090 for the real project. They're rather pricey so that's
> all I'm buying for now.
>
> The web site really doesn't give you an idea of how tiny these LEDs
> are. They are an extremely intense point of light that actually
> stings your finger like sunshine from a magnifying glass. They're
> crazy bright.
>
> The K2 heatsink was a disaster so I was a bit skeptical about the odd
> Rebel heatsink. I was pleasantly surprised to find that it works very
> well. You solder it to copper and the LED stays cool even when
> overdriven to 1A.
>
> I abused a 0040 by soldering it to a 1x1x.125 inch copper tab and
> driving it at 1A. After working well for a while it dimmed and
> unsoldered itself. It worked again when it cooled.
>
> The quality of the Rebel seems to be higher than the K2. I ordered
> about 30 K2s for projects and all were extremely off electrical spec
> and some had bubbles in the lenses. So far the Rebels meet their
> electrical specs and seem to be free of defects. Forward voltage is
> very stable and consistent.
>
> I used the 0040 LEDs to experiment with hobbyist soldering options.
> I'd love to solder these to a thin film PCB and glue that to an
> aluminum heatsink but I can't find thin film PCBs for public sale :(
> You can't simply solder these to the edge of a copper bar because
> they'll float away as soon as the solder melts. I found two options
> that work. You can drill 4 small holes in the heatsink around the
> thermal pad contact area. Excess solder flows into these holes and
> surface tension centers the LED. Another option is a tiny dab of
> silicone glue on the exposed ceramic area. Hang the power tabs over
> the edge of the heatsink so you can solder on wires.
>
> The tiny size of the Rebel begs for them to be built into
> ultra-compact flashlights. I wouldn't think of them as 3W LEDs
> because they're too inefficient at that point. If you have that much
> room for a heatsink then you might as well use bigger LEDs. Think of
> them as 1W LEDs that can be momentarily driven to 3.5W when you need
> an emergency boost.
>
> So the project now -
>
> I'm using a switching regulator based on the LM2679 and a Zetex
> current sensor chip to drive 10 LXML-PWC1-0090 Rebels into 18mm
> lenses. The idea is that the tiny size of the Rebel lets me run many
> LEDs at an efficient current rather than a few large LEDs at an
> inefficient current. My goal is 1W to 10W for normal operation and
> momentary capability to 40W. Dimming will use voltage feedback at
> low power and current feedback at high power. I got a prototype
> power supply running very well before I dropped it and bent $50 in
> surface mount power components. All the copper parts are cut for the
> real thing. I still need a few electrical parts and a thermally
> conductive body. Carbon fiber with a pyrolytic graphite sheet liner
> might do the trick. The final size should be around 6x2.5x1.5
> inches. Input power will be 9V to 40V DC.
>
> Until this project is done, my K2 (LXK2-PW14-U00) bike light works
> quite well. The new project is half for fun and half to create a
> light that can be hand-held too.

The consumer products out right now from the far east are really kickin' it.
Rebel 100s, etc. For me, I'm staying with the Crees at the moment. I've
never been good with soldering and really don't want to bother with
soldering more stars... Bare Rebels are probably ridiculous to handle as you
say. I can only imagine.

The die size of a Rebel is roughly the same (1mm^2) as the Cree/Seoul. The
packaging is tiny though.

Cree ran 1000 lumens through an R&D sample (4A@~3.7V) recently. I wonder
when that will trickle down to consumer-grade stuff. Probably requires
liquid nitrogen.

--
Phil

[russellseaton1@yahoo.com]

On Sep 3, 9:30 pm, "Phil" <n...@try.to> wrote:

> Check out the headlamp Princeton Tec EOS Cree/Seoul mod. I use it for night
> riding in dark areas.

Please post the bulb model and source for ordering. I have the
Princeton Tec EOS Bike helmet light and would not mind getting more
light out of it.

[SMS]

Phil wrote:

> The consumer products out right now from the far east are really kickin' it.
> Rebel 100s, etc. For me, I'm staying with the Crees at the moment. I've
> never been good with soldering and really don't want to bother with
> soldering more stars... Bare Rebels are probably ridiculous to handle as you
> say. I can only imagine.
>
> The die size of a Rebel is roughly the same (1mm^2) as the Cree/Seoul. The
> packaging is tiny though.

It's not just the heat dissipation that's an issue with these LEDs,
though that's a very big issue, it's precisely positioning the LED in
the reflector, something that's damn near impossible to do by hand. You
end up with the same problem that plagues a lot of lights where you're
not projecting a good beam because the lens and bulb (or LED) aren't
well-matched. It's the main reason that the MR series of halogen bulbs
was developed.

I'm very pleased with the Fenix L2DCE (CE=Cree Edition) as a bicycle
light. $53 plus the cost of a handlebar mount flashlight holder. It
won't replace the lights on my commute bike, but it's more than
sufficient as a light to move between bicycles.

I recall a few years ago someone was espousing the virtues of LED
lights, and one of the benefits he came up with was something like "no
white hot filament." Obviously he didn't understand anything about
semiconductor physics and junction current and temperatures (Tj).
There's no free lunch here. There is heat, a lot of heat, to deal with
in both LEDs and incandescent sources.

[autopi]

> I'm very pleased with the Fenix L2DCE (CE=Cree Edition) as a bicycle
> light. $53 plus the cost of a handlebar mount flashlight holder. It
> won't replace the lights on my commute bike, but it's more than
> sufficient as a light to move between bicycles.

I was considering getting a Fenix L2DCE myself, based on comments
here. Can you say a bit more about what kind of commuting you are
doing, which lights you use and how the Fenix compares? I have pretty
moderate needs as far lighting goes--5 miles in the city (and not
every night, either)--and $50 is about as much as I want to spend on
lights, so I was hoping this would be the answer.

Thanks!

p.s. how have you found the handlebar mount--is it secure? I cross a
number of train tracks and that's been sufficient to knock stuff off
my bike on occasion...

[frkrygow@gmail.com]

On Sep 16, 9:59 pm, SMS <scharf.ste...@geemail.com> wrote:
>
>
> I recall a few years ago someone was espousing the virtues of LED
> lights, and one of the benefits he came up with was something like "no
> white hot filament." Obviously he didn't understand anything about
> semiconductor physics and junction current and temperatures (Tj).
> There's no free lunch here. There is heat, a lot of heat, to deal with
> in both LEDs and incandescent sources.

There is certainly heat to deal with. But are you suggesting that the
junction of the LED _is_ white hot - that is, several thousand
degrees Kelvin?

- Frank Krygowski

[SMS]

autopi wrote:
>> I'm very pleased with the Fenix L2DCE (CE=Cree Edition) as a bicycle
>> light. $53 plus the cost of a handlebar mount flashlight holder. It
>> won't replace the lights on my commute bike, but it's more than
>> sufficient as a light to move between bicycles.
>
> I was considering getting a Fenix L2DCE myself, based on comments
> here. Can you say a bit more about what kind of commuting you are
> doing, which lights you use and how the Fenix compares? I have pretty
> moderate needs as far lighting goes--5 miles in the city (and not
> every night, either)--and $50 is about as much as I want to spend on
> lights, so I was hoping this would be the answer.

On my normal commute bike I have two 14W sealed beam headlights, though
usually turning only one of them on is sufficient. Commute is about
eight miles, mainly on suburban streets, but some multi-lane higher
speed roads. These lights enable me to ride at a fairly fast pace
without getting cut off by vehicles. In terms of seeing the road, I
could probably get by with less powerful lights, but I'd lose the
advantage of being perceived as something other than a bicycle. See
"http://www.nordicgroup.us/s78/images/img_0281.jpg".

On the bikes I use for other activities I don't want a permanent setup
but I still want safer lights than the usual $20 battery powered
headlight or dynamo headlight. I may get a hub dynamo wheel for my
folding Dahon as it may be nice for short trips around town to not have
to always be attaching another light.

> Thanks!
>
> p.s. how have you found the handlebar mount--is it secure? I cross a
> number of train tracks and that's been sufficient to knock stuff off
> my bike on occasion...

I've only had that handlebar mount a few days. I was concerned about it
as it's only plastic with some detents. However I did try simulating
bumps, and I tried pulling it open without pulling the end forward to
release the tab from the detents, and it held. You could also
criss-cross a velcro cable tie
("http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94153"
or
"http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94152")
around it if you're concerned about it opening on its own.

The TwoFish LockBlock, uses velcro and rubber blocks, but it too is a
little two big for the very small diameter Fenix L2DCE.

See "http://nordicgroup.us/s78/flashlights.html" for details on using
flashlight type lights on your bicycle.

It's ironic that many of these flashlights project a much more bicycling
compatible beam than dedicated bicycle lights, many of which do not have
sufficient beam spread or spillover to illuminate off to the side.

Steve
http://bicyclelighting.com
Earth's Independent Source for Bicycle Lighting Information