A bright idea.

[Metro]

"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97pr14Ft36U3@mid.individual.net...

**Of course. Many ignorant folk seem to think that LEDs run cool.

What do define as cool?

 

[yaputya]

"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97pr14Ft36U3@mid.individual.net...

yaputya wrote:
"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97pk4uFhf5U3@mid.individual.net...
yaputya wrote:
"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97nae3Fi1cU3@mid.individual.net...
Metro wrote:
"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97k7kqFvj7U3@mid.individual.net...
Peter wrote:
Light bulbs used to cost $0.15-$1.50 then we were told it is
better for the environment and our pocket to replace (even
working) light bulbs with new ones that cost $5-$10 although
these ones are being replaced orverseas with even newer ones
that are more environmental and economical at a cost of $20'ish
each.

**Idiot. Let's examine some real world facts, as opposed to your
abject nonsense:

In my home, I have around 20 CFLs. MAXIMUM cost was $6.00 (for a
high quality, Philips 23 Watt). Most were much less expensive.
In 6 years, I've experienced TWO failures. One was caused by a
wayward possum and the other was in a 'trouble' lamp, which I
dropped onto a rock and punctured the tube. The CFLs are used
from between a few minutes per day and several hours per day.

I also have a dozen or so 50 Watt halogen downlights. These are
used VERY infrequently, due to the nonsensically high power
consumption. I've had 7 failures in 6 years. Cost of each
downlight is around $3.00. I have one, 100 Watt tungesten
incandescent. It is used less than 1
hour per month and has failed three times in 6 years. Replacement
cost was (last I purchased one) about $4.00. Unfortunately, the
light fitting is unsuitable for any other type of lamp.


--
Trevor Wilson
www.rageaudio.com.au

Obviously you will change the fitting.........

**Just waiting for a suitable LED replacement.

LEDs ain't the ants pants either...
I recently bought a 5W 12VAC LED light in MR16 26deg. spotlight form
that was on special - I got for about AUD10. I thought it would run
much cooler than the halogen it replaces - well it does, but it
still gets hot enough to boil water.
It is somewhere between a 10W and 20W halogen in brightness, but
while an enclosed halogen bulb is happy to run hot without any
heatsinking, the LED needs a complex cast aluminium heatsink that
gets very hot. Turns out that these high power lighting LEDs
dissipate around 85% of the power in heat - so only low-power LEDs
run cool. The hotter the LED gets the shorter its life and the
light output also goes down - so your 10,000 hour 450 cd LED may
not get anywhere near that if it is running hot.
The bottom line is that light fittings designed for halogens may not
be suitable for LEDs due to inadequate ventilation. Beware !
The solution is to use fittings actually designed for LEDs and not
to retrofit LEDs into old halogen fittings.

**I am well aware of the issues and limitations associated with
LEDs. I am also aware that around 15 Watts of LED power is required
to equal a 50 Watt halogen. This has never been much of a mystery.
Cheap LED lamps are jsut as bad as cheap CFLs. Also no mystery.

I assume by 'lamp' you mean light fixture or luminaire.

**Correct.

The point is that although the LED array itself might be much more
efficient than a similar halogen, the luminaire has to be taken
into consideration when evaluating the overall efficiency - and
substituting LED arrays for halogen bulbs in ANY luminaire can
lead to overheating, regardless of "cheap" or "expensive".

**Of course. Many ignorant folk seem to think that LEDs run cool.

--
Trevor Wilson
www.rageaudio.com.au

I guess that is understandable if you haven't actually used a high-power
LED.
I've used several Luxeon Star-O 1W LEDs for torches and a bedside reading
lamp, and they have minimal thermal problems. But once you get over a few
watts the shit hits the fan, so to speak, as you are obviously well aware.

For those thinking about designing with LED chip arrays, the following
link (and other useful stuff on the same site) is recommended.
http://bridgelux.com/assets/files/AN10_Thermal_Management_of_LED_Arrays.pdf

 

[yaputya]

"Metro" <Home@home> wrote in message
news:4e17ef76$0$19225$afc38c87@news.optusnet.com.au...

"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97pr14Ft36U3@mid.individual.net...


**Of course. Many ignorant folk seem to think that LEDs run cool.

What do define as cool?

Cool to touch is the commonly accepted meaning in this context.
A rough definition would be cool enough to comfortably maintain contact.
Maybe less than around 65degC maximum ?
The MR16 5W LED units mentioned run much hotter than that.

 

[Trevor Wilson]

Metro wrote:

"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97pr14Ft36U3@mid.individual.net...


**Of course. Many ignorant folk seem to think that LEDs run cool.

What do define as cool?

**Ambient temperature.


--
Trevor Wilson
www.rageaudio.com.au

 

[T.T.]

"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97s56rFmh6U3@mid.individual.net...

Metro wrote:
"Trevor Wilson" <trevor@rageaudio.com.au> wrote in message
news:97pr14Ft36U3@mid.individual.net...


**Of course. Many ignorant folk seem to think that LEDs run cool.

What do define as cool?

snip

If anyone can define "cool" for me, I would be grateful.
I regularly get emails from Debbie and Cassie and Amanda and several Russian
young ladies, with all of whom I apparently share a friend who says I am a
"cool guy".
They all want to be my friend and some even want to send me photographs.
So being cool must be a good thing.