Today's Message Index:
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1. 09:45 AM - Re: LED landing light filter experiment (SWAN MGT LLC/M WYNN)
2. 12:52 PM - Re: LED landing light filter experiment (Robert L. Nuckolls, III)
3. 07:51 PM - Re: LED landing light filter experiment (Eric Page)
Message 1
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| Subject: | Re: LED landing light filter experiment |
Thanks for the replies.
I cannot answer your first questions until further education on my
part. However, by re-reading your para 2 & 3, the fog is thinning!
Thanks.
Currently there are no resisters in series with the LED. The "operating
point" will be the aircraft battery / alternator system buss. Apparently
your "switch mode supply" handles well any voltage fluctuation event, as
referenced in para 3. Point well made. We will go with that item.
Since posting my last question, I've located for sale a multi-vdc 30
watt RGB LED, with a separate contact tab for each color, as opposed to
a ganged contact used with remote LED controls for color choice. (My
terminology may not be perfect here...) This LED-heat sink package
should (as you stated) fit my needs much better than "filtering white
light thru red and green glass wingtip filter lens." I'll plan on
using the white LED's only as strobes.
As always, the education one receives from the build-it-yourself effort
is well worth the initial confusion.
Best regards,
Mike W.
****************
----- Original Message -----
From: Robert L. Nuckolls, III
To: aeroelectric-list@matronics.com
Sent: Friday, January 25, 2013 7:46 PM
Subject: Re: AeroElectric-List: LED landing light filter experiment
At 04:19 PM 1/25/2013, you wrote:
Thanks Bob.
I'm with you for about 75% of the electro-magic here.
My real world [table top] on the test bench: My design rated 12 vdc
6000k LED [with heat sink attached] is working very well "pulling 10 vdc
and 500 ma." Power supply is a Micronta Dual Tracking Adjustable DC
Power Supply. If I understand you correctly, the main (only?) reason
that I should add another component [the LED driver] is to insure a
steady-state current supply to my LED? PS: My final lighting goal is
to use these (mounted under FAA-PMA red, green & clear glass lens) for
wing-tip and tail nav lights, and to strobe them (white) at the same
positions.
Your thoughts are sincerely appreciated. There is only so much that
one can gain from studying texts... ;)
Are you using any series resistance in your installtion?
How do you intend to establish and maintain the desired
500 mA operating point? What the rated operating current
for the device. Are these white lights that you're going
to filter into red and green? Keep in mind that filters
of white light are VERY inefficient. They block a majority
of the lamp's total output allowing only the desired color
to pass. If you use leds designed to produce red and green
light, then no filtering (with attendant losses) are
necessary.
But assuming that you DO use three such arrays at 500
ma each. Then you need to drop about 5 volts in a resistor
in series with each array for 2.5 watts each. That's
7.5 watts tossed off in heat for each fixture with 15 watts
being used by the lamps. Should the alternator quit,
your bus drops to 12v and you now bias each array at
only 200 mA for a 60% drop in light output.
Now, if you hook all the lamps in series and power them
with a 500 mA constant current switchmode supply, the
light output can remain constant throughout an operating
range of 10 to 15 volts for the bus with only a couple of
watts tossed off by the supply. That's what these guys
do for the OBAM aircraft position lights that were being
discussed here on the list a few years back. This particular
supply will put out any practical excitation value between
100 and 1000 mA . . . and is filtered.
Bob . . .
Message 2
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| Subject: | Re: LED landing light filter experiment |
> Since posting my last question, I've located for sale a multi-vdc
> 30 watt RGB LED, with a separate contact tab for each color, as
> opposed to a ganged contact used with remote LED controls for color
> choice. (My terminology may not be perfect here...) This LED-heat
> sink package should (as you stated) fit my needs much better than
> "filtering white light thru red and green glass wingtip filter
> lens." I'll plan on using the white LED's only as strobes.
Hmmmm . . . multi-colored devices also suggest
less than the best efficiency compared to a single
color device. I'm pretty sure that the most successful
LED replacements for incandescent lamps will be
single color-specific devices.
Bob . . .
Message 3
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| Subject: | Re: LED landing light filter experiment |
Mike,
RGB devices like the one you found are intended to be driven by a controller
that can vary the intensity of each color as required to achieve "full colo
r" output. The eye mixes the colors so you "see" the intended color -- thin
k of each device as akin to a single pixel in a color "jumbotron" stadium sc
reen and you'll have the basic idea.
For aircraft position lights, you'd probably be better off from an output in
tensity, size and cost perspective to find suitable single-color LEDs.
Pay close attention to color wavelength with LEDs. Their output is very nar
row and specific. Red doesn't necessarily mean red and green doesn't necess
arily mean green. Both colors have specifically defined wavelengths as far a
s the FAA is concerned.
Also pay close attention to beam angles. LEDs come with all kinds of optics
molded into them. Wide angles obviously cover more area, but throw less li
ght in any given direction. Narrow beam devices throw more light, but you'l
l need more of them, carefully aimed, to cover the desired viewing area.
I believe it was the other Eric who posted something a few months back about
LED use for aircraft position lighting. I recall something about aviation g
reen being very hard to duplicate with LEDs. Perhaps you can find it in the
archives, or the OP will see this and kindly repost.
Eric
On Jan 26, 2013, at 11:43 AM, "SWAN MGT LLC/M WYNN" <wynaire@citlink.net> w
rote:
> Thanks for the replies.
> I cannot answer your first questions until further education on my part. H
owever, by re-reading your para 2 & 3, the fog is thinning! Thanks.
>
> Currently there are no resisters in series with the LED. The "operating po
int" will be the aircraft battery / alternator system buss. Apparently your "
switch mode supply" handles well any voltage fluctuation event, as reference
d in para 3. Point well made. We will go with that item.
>
> Since posting my last question, I've located for sale a multi-vdc 30 wat
t RGB LED, with a separate contact tab for each color, as opposed to a gange
d contact used with remote LED controls for color choice. (My terminology ma
y not be perfect here...) This LED-heat sink package should (as you stated) f
it my needs much better than "filtering white light thru red and green glass
wingtip filter lens." I'll plan on using the white LED's only as strobes
.
>
> As always, the education one receives from the build-it-yourself effort is
well worth the initial confusion.
> Best regards,
> Mike W.
> ****************
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