On Aug 1, 3:27 pm, "Hilton" wrote:
Dean,

Congrats on the new product. Make sure Julie at AOPA and the various mags
get the press release.

My knowledge of LEDs is: pick an LED, add a 1K resistor and a 9V and you're
good to go - back from my hobby electronic days . I had a quick question
about the temperatures. Death Valley gets to 120-130F (I believe). If you
run the LED as an anti-collision system during take/off and landing,
couldn't you get about (or at least close to) the 150F?

Thanks,

Hilton

wrote in message

oups.com...



On Jul 25, 7:14 am, Denny wrote:
Just some general comments - not aimed at Dean's product...

LED has been touted as the end all and be all of lighting, replacing
the incandescent bulb... However, the emperor's new clothes may be a
bit revealing...

First, is that LED lights require substantial heat sinks and adequate
ventilation in order to function... (Dean's product looks competently
designed for this)... Failure to adequately cool the LED will result
in short service life... An adequate heat sink often erases any size
advantage the LED started out with...
Initial installation cost of LED light assembly is markedly higher
than an incandescent... Colreg approved LED running lights for boats
are downright expensive...
Replacement cost of LED lighting that fails in service is vastly
higher than simply replacing a $20 bulb...
By the time the LED assembly is properly cooled with a heatsink the
weight advantage of LED is markedly lessened...
Voltage control is more stringent for proper functioning of LED light
assemblies, as opposed to incandescent filament bulbs..
Dimmers for LED lights are expensive for technical reasons...

In boats/yachts where extended operation from a battery set is a way
of life there has been a rush to replace incandescent with LED due to
it's more efficient use of watt hours... The experience with that has
shown that LED has its place, but it is not a blanket replacement...
For task lighting, such as spot lighting over a galley counter, the
LED is excellent... It is also excellent for lighting of stair steps,
in the head, inside of cabinets, drawers and closets, and night
lights...For general cabin lighting (even lighting of large areas) the
cold cathode and fluorescent lights are still preferred... For high
intensity tasks, such as deck lights, anchor raising lights, and spot
lights, the halogen bulb still reigns supreme... For a reading light,
the jury is still out - and I personally have not found a light my
eyes like better than the incandescent for extended periods of
reading... For mast lights and running lights the LED is making
progress, but initial cost and light output is still an issue...

Things are never as simple as they seem... Now, this is not intended
to begin a debate over Dean's product, it is simply remarks on what I
have found in the 2 years of research for outfitting my boat... What
that means in an aircraft is up to you...

denny

Denny,

You are correct that proper heat sinking is essential to preserving an
LED. Exceeding the rated junction temperature of an LED will result
in it failing long before its rated life. Our design guarantees that
the LEDs will remain at least 40C below their maximum junction
temperature of 150C even on the hottest day at full power. We have
had many people come by our exhibit in the North Aircraft area wanting
to know why the device has such a large heat sink and weighs 0.9
pounds (just under 1 pound).

Most people who experiment with LEDs just hook them up to a current
limiting resistor and call it good. That is really not a good
practice for an airplane. Our product has a switching supply that
regulates the LED current for an input voltage range of 9V to 36V
which guarantees reliable operation. It is also protected against
voltage spikes, ESD, and lightning transients. We have also conducted
DO-160E RFI and conducted emissions tests to ensure that it does not
interfere with radios or anything on the electrical system.

To really appreciate how well our landing light works, you have to see
it at night. We have demoed it to a few people after 9pm. We
generate a lot more light than a 55W halogen at less that 1/2 the
power.

We arrived at Oshkosh at 12:15 on Saturday when the sun was very
bright, and the controller at Fisk called us out as the high wing with
blue stripes on the wings and flashing lights (wig wag mode was on).
We were happy to hear that!

Dean
AeroLEDs LLC
www.aeroleds.com- Hide quoted text -

- Show quoted text -

I have tinkered with high brightness LEDs for some time. My conclusion
was LEDs significantly outperform other sources only in situations
where you need single color, such as nav lights, red cockpit lights,
traffic lights etc... For white light applications their performance
is less impressive. That is reasonable because LEDs inherently produce
single color photons, while incandescent sources produce a broadband
of photons. You lose efficiency converting a broad band to a single
color, and you also lose efficiency converting a single color to a
broad band.

Also, it is not fair to just compare the brightness. You should also
consider the weight of the heat sink and extra circuitry. In addition,
LED lamps are typically thermally bonded to their heat sinks so
individually replacing burnt out LED may be difficult or impossible.
You might have to replace the whole array. They are insensitive to
vibration, but are more sensitive to temperature fluctuations.