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Guest
Thu Sep 22, 2011 6:40 pm
On Wed, 21 Sep 2011 13:26:48 -0700 (PDT), fungus
<openglMYSOCKS_at_artlum.com> wrote:
Quote:
On Sep 21, 5:37 pm, default wrote:
Up to 100 watt modules...
Try searching for "150W LED"... :-)
http://www.ebay.com/sch/i.html?_nkw=150w+led
The 1-5 watt modules need a lot of heatsink if they are to survive
summer outdoors, the 100 watt beast is probably hard to cool. The
"star" mounted leds aren't good to go - that little aluminum chunk is
just a heat spreader not a heat sink.
The big ones seem to use PC CPU coolers for cooling
(i.e. with heatpipes and fans).
My 10W came bolted to a heatsink so I'm guessing
it's supposed to be able to cope. Still too hot to touch
though...
Out of my league perhaps...
If I have to get that fancy a fluorescent light makes more sense.
Guest
Thu Sep 22, 2011 8:53 pm
On Thu, 22 Sep 2011 12:36:03 -0700 (PDT), fungus
<openglMYSOCKS_at_artlum.com> wrote:
Quote:
On Sep 22, 8:39 pm, default wrote:
I tend to run them under current in everything. There seems to be no
standardized specifications, and even if there were, it is not easy to
figure out how much heat sinking one needs.
I figure the ebay sellers are making wild claims
about wattage to up the prices ("20W" sells
for more than "10W").
Most Ebay sellers. Particularly China.
Quote:
I did a thermometer with LEDs to signal the temperature outside. I
used a tri color high flux (piranha style square package) with a
picaxe to do the logic and a DS18B20 for a (digital) sensor.
The next project in my head project involves high power
RGB leds and an Arduino...
It flashes the temperature tens then a pause and units.
Let's hope it's Celsius...
Actually no, Fahrenheit has better resolution, and I'm in the US and
used to it. The reason for using colors is that it makes it fairly
easy to count. Tens flash more slowly than units and most of the time
I just have to count units. The chip has raw resolution of something
like .065 degrees C...
It sounds unwieldy to describe it - but in a day or two it is second
nature.
fungus
Guest
Thu Sep 22, 2011 9:36 pm
On Sep 22, 8:39 pm, default wrote:
Quote:
I tend to run them under current in everything. There seems to be no
standardized specifications, and even if there were, it is not easy to
figure out how much heat sinking one needs.
I figure the ebay sellers are making wild claims
about wattage to up the prices ("20W" sells
for more than "10W").
Quote:
I did a thermometer with LEDs to signal the temperature outside. I
used a tri color high flux (piranha style square package) with a
picaxe to do the logic and a DS18B20 for a (digital) sensor.
The next project in my head project involves high power
RGB leds and an Arduino...
Quote:
It flashes the temperature tens then a pause and units.
Let's hope it's Celsius...
fungus
Guest
Fri Sep 23, 2011 2:06 pm
On Sep 22, 10:53 pm, default wrote:
Quote:
On Thu, 22 Sep 2011 12:36:03 -0700 (PDT), fungus
I figure the ebay sellers are making wild claims
about wattage to up the prices ("20W" sells
for more than "10W").
Most Ebay sellers. Particularly China.
I just received another LED, it's 20W and
comes attached to a heatsink.
I wanted to see what happens when you run
a 20W LED with a 10W driver (which is what
I'm planning to do...)
The heatsink looked quite big in the photos but
it's really no bigger then the heatsink on my
10W LED.
It gets too hot to touch at 10W, not quite as hot
as the 10W LED but still pretty damn hot. There's
NO WAY that's going to run at 20W and survive.
On the plus side it definitely puts out more light
at that power than the 10W LED does. I think it
will be workable with a bit of tweaking (different
heatsinks or maybe a different controller board).
Quote:
Let's hope it's Celsius...
Actually no, Fahrenheit has better resolution
I was just thinking Celsius would be less flashes
to count.
Guest
Fri Sep 23, 2011 2:59 pm
On Fri, 23 Sep 2011 05:06:46 -0700 (PDT), fungus
<openglMYSOCKS_at_artlum.com> wrote:
Quote:
On Sep 22, 10:53 pm, default wrote:
On Thu, 22 Sep 2011 12:36:03 -0700 (PDT), fungus
I figure the ebay sellers are making wild claims
about wattage to up the prices ("20W" sells
for more than "10W").
Most Ebay sellers. Particularly China.
I just received another LED, it's 20W and
comes attached to a heatsink.
I wanted to see what happens when you run
a 20W LED with a 10W driver (which is what
I'm planning to do...)
The heatsink looked quite big in the photos but
it's really no bigger then the heatsink on my
10W LED.
It gets too hot to touch at 10W, not quite as hot
as the 10W LED but still pretty damn hot. There's
NO WAY that's going to run at 20W and survive.
On the plus side it definitely puts out more light
at that power than the 10W LED does. I think it
will be workable with a bit of tweaking (different
heatsinks or maybe a different controller board).
Err on the side of caution, particularly when they are expensive.
I have a 120 VAC 7.5 watt Led light bulb. Figuring that the
refrigerator would benefit most I spent the $15 it cost. Alas the
heat sink at the base precludes it from fitting in the socket and most
of the light comes out the end. Great for a table lamp though.
It gets hot to the touch after being on a few hours but not scalding
hot, maybe ~120F.
Leds don't usually die completely just get dimmer with time. That's
where some standardization in testing needs to be done. So they last
50,000 hours - but they are down to half the light output at 10,000
hours.
Quote:
Let's hope it's Celsius...
Actually no, Fahrenheit has better resolution
I was just thinking Celsius would be less flashes
to count.
Yes but... I seldom have to count the tens since the temperature
doesn't change that dramatically and the color changes make it a lot
easier to "count." Tens flashes slower than units - all those things
make reading it almost automatic after a short while. (and it looks
good coming through a glass block wall)
fungus
Guest
Fri Sep 23, 2011 5:07 pm
On Sep 23, 4:59 pm, default wrote:
Quote:
Leds don't usually die completely just get dimmer with time.
So they gradually reduce their own power to a
level their heatsink can cope with...?
That's very clever.
Ecnerwal
Guest
Sat Sep 24, 2011 1:50 pm
In article <r96p77plm64l9ov6qd8qpqh9uac30qps7e_at_4ax.com>, default wrote:
Quote:
Leds don't usually die completely just get dimmer with time. That's
where some standardization in testing needs to be done. So they last
50,000 hours - but they are down to half the light output at 10,000
hours.
....the standard is actually 70% light output - so at 50,000 hours, it's
still on but at 70% of rated output. What you get from Chinese "brands"
that change every week so they are never around for warrantee problems
may differ. What you get if you overheat the die will also differ.
--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
Guest
Sat Sep 24, 2011 5:57 pm
On Fri, 23 Sep 2011 08:07:53 -0700 (PDT), fungus
<openglMYSOCKS_at_artlum.com> wrote:
Quote:
On Sep 23, 4:59 pm, default wrote:
Leds don't usually die completely just get dimmer with time.
So they gradually reduce their own power to a
level their heatsink can cope with...?
That's very clever.
No, not at all. They reduce the light output for the same power
dissipated. Specified in "Half-life." 50% luminous output at X
hours.
For instance my first night light used 3 red LEDs and was on
continuously for 5 years, at 2 years it was already down to half
brightness (subjectively) and probably half again in 4, and at 5 it
was only good for finding where the outlet was in the dark.
Some of the fancier "light engines" contain current regulators that
lower the output with high temps protecting the LEDs...
Guest
Sat Sep 24, 2011 5:58 pm
On Sat, 24 Sep 2011 09:50:45 -0400, Ecnerwal
<MyNameForward_at_ReplaceWithMyVices.Com.invalid> wrote:
Quote:
Cats, coffee, chocolate...vices to live by
Vivaldi and home brew beer too.
fungus
Guest
Sat Sep 24, 2011 8:59 pm
On Sep 24, 7:57 pm, default wrote:
Quote:
On Fri, 23 Sep 2011 08:07:53 -0700 (PDT), fungus
openglMYSO...@artlum.com> wrote:
On Sep 23, 4:59 pm, default wrote:
Leds don't usually die completely just get dimmer with time.
So they gradually reduce their own power to a
level their heatsink can cope with...?
That's very clever.
No, not at all.
Maybe I was too subtle...I meant the overheating
makes them dimmer so they're 'auto-adjusting'
themselves to the heatsink.
fungus
Guest
Sat Sep 24, 2011 9:28 pm
On Sep 24, 3:50 pm, Ecnerwal
<MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote:
Quote:
What you get from Chinese "brands" that change every week
so they are never around for warrantee problems may differ.
What you get if you overheat the die will also differ.
Some of the eBay sellers seem fairly serious.
The place I bought my small LEDs and controller
boards from provides proper datasheets, schematics,
etc. for everything (I'm guessing they manufacture
at least the controller boards themselves - the boards
are branded and nobody else on eBay has them).
Their warranty only covers DOA but I'm guessing
the LEDs you buy from 'reputable' places are
probably made in China too and will fail at about
the same rate. Buy some spares...
Guest
Sun Sep 25, 2011 1:56 pm
On Sat, 24 Sep 2011 11:59:04 -0700 (PDT), fungus
<openglMYSOCKS_at_artlum.com> wrote:
Quote:
On Sep 24, 7:57 pm, default wrote:
On Fri, 23 Sep 2011 08:07:53 -0700 (PDT), fungus
openglMYSO...@artlum.com> wrote:
On Sep 23, 4:59 pm, default wrote:
Leds don't usually die completely just get dimmer with time.
So they gradually reduce their own power to a
level their heatsink can cope with...?
That's very clever.
No, not at all.
Maybe I was too subtle...I meant the overheating
makes them dimmer so they're 'auto-adjusting'
themselves to the heatsink.
Overheating permanently reduces the light output (forever no recovery)
Running them hot decreases efficiency reducing the light output but
only while hot (and there's a fine line between hot and overheated).
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