LED / Nav lights

Recently I posted some questions regarding this issue. After some
experimentation, it appears that LEDs and inexpensive strobes are indeed
a feasible option for experimental a/c.

Following a presentation at our recent EAA meeting, our most senior DAR
liked the mock-ups so well that he will install some LEDs on his own
plane! He has no problem approving an appropriate LED/nav installation
as long as the visibility geometry is appropriate.

To see an article on using LEDs and inexpensive strobes, feel free to
visit our EAA site, scroll down to the member news area and click on the
obvious link. http://www.eaa724.org/

Scott Gettings
Glass Goose

"Scott Gettings" wrote

To see an article on using LEDs and inexpensive strobes, feel free to
visit our EAA site, scroll down to the member news area and click on the
obvious link. http://www.eaa724.org/

Scott Gettings
Glass Goose

It was not so obvious to me. How about a direct link, or a clue?
--
Jim in NC


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Morgans wrote:
"Scott Gettings" wrote


To see an article on using LEDs and inexpensive strobes, feel free to
visit our EAA site, scroll down to the member news area and click on the
obvious link. http://www.eaa724.org/

Scott Gettings
Glass Goose


It was not so obvious to me. How about a direct link, or a clue?
try:
http://www.eaa724.org/MeetingsEvents...rMeeting031004
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"Evan Carew" wrote
try:
http://www.eaa724.org/MeetingsEvents...rMeeting031004

Thanks. Good stuff.
--
Jim in NC


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Sorry this was not so "obvious".

Scroll about 1/4 way down the page and click on the "more" beside the picture
of the nav/strobe light demonstration.

Scott

Morgans wrote:

"Scott Gettings" wrote

To see an article on using LEDs and inexpensive strobes, feel free to
visit our EAA site, scroll down to the member news area and click on the
obvious link. http://www.eaa724.org/

Scott Gettings
Glass Goose

It was not so obvious to me. How about a direct link, or a clue?
--
Jim in NC

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.629 / Virus Database: 403 - Release Date: 3/17/2004

On Sat, 20 Mar 2004 00:25:32 GMT, Scott Gettings
wrote:

Sorry this was not so "obvious".

Scroll about 1/4 way down the page and click on the "more" beside the picture
of the nav/strobe light demonstration.

Just went through the information on the page and it looks good as
well as interesting. However I'd like to offer a warning.

The math and resistor rating concern me a tad. I may have misread, or
mis-calculated, but...

It talks about using two LEDs and dropping 7 volts at 0.35 A or ( 350
ma) and using a half watt, 20 ohm resistor.

It mentions the resistor getting hot. It should, they are over rating
the resistor by over a factor of 4 and that is with no safety factor.
It's not uncommon for a resistor to get hot, but they should not get
so hot you have to be concerned about them except in the case of wire
wound power resistors which may actually run quite hot.

R does = E/I and in this case 7/0.35 = 20 ohms but it needs to be
carried one step farther and figure the power as well.

Two ways, the first is simply the voltage times the current. You are
dropping 7 volts at 0.35 A = 2.45 watts.
Another way is P = I^2*R, or current squared multiplied by the
resistance. or (0.35 * 0.35) = 0.1225 * 20 = 2.45 watts.

Normally, we double the rating for safety so you need a 5 Watt
resistor, not a half watt.

You are dissipating 2.45 watts in a half watt resistor.
You could get away with that if the lights were pulsed, but in this
case they are on all the time. That much heat will cause the
resistor value to change and is a definite fire hazard.

Normally the resistor gets too hot and breaks, but I have see the
things start glowing. When they do that the resistance can become
quite low, rather than high and you run the risk of shorting the LEDs
which would increase the current even more.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Scott

Morgans wrote:

"Scott Gettings" wrote

To see an article on using LEDs and inexpensive strobes, feel free to
visit our EAA site, scroll down to the member news area and click on the
obvious link. http://www.eaa724.org/

Scott Gettings
Glass Goose

It was not so obvious to me. How about a direct link, or a clue?
--
Jim in NC

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.629 / Virus Database: 403 - Release Date: 3/17/2004

Roger Halstead wrote:

On Sat, 20 Mar 2004 00:25:32 GMT, Scott Gettings
wrote:

Sorry this was not so "obvious".

Scroll about 1/4 way down the page and click on the "more" beside the picture
of the nav/strobe light demonstration.

Just went through the information on the page and it looks good as
well as interesting. However I'd like to offer a warning.

The math and resistor rating concern me a tad. I may have misread, or
mis-calculated, but...

It talks about using two LEDs and dropping 7 volts at 0.35 A or ( 350
ma) and using a half watt, 20 ohm resistor.

It mentions the resistor getting hot. It should, they are over rating
the resistor by over a factor of 4 and that is with no safety factor.
It's not uncommon for a resistor to get hot, but they should not get
so hot you have to be concerned about them except in the case of wire
wound power resistors which may actually run quite hot.

R does = E/I and in this case 7/0.35 = 20 ohms but it needs to be
carried one step farther and figure the power as well.

Two ways, the first is simply the voltage times the current. You are
dropping 7 volts at 0.35 A = 2.45 watts.
Another way is P = I^2*R, or current squared multiplied by the
resistance. or (0.35 * 0.35) = 0.1225 * 20 = 2.45 watts.

Normally, we double the rating for safety so you need a 5 Watt
resistor, not a half watt.

You are dissipating 2.45 watts in a half watt resistor.
You could get away with that if the lights were pulsed, but in this
case they are on all the time. That much heat will cause the
resistor value to change and is a definite fire hazard.

Normally the resistor gets too hot and breaks, but I have see the
things start glowing. When they do that the resistance can become
quite low, rather than high and you run the risk of shorting the LEDs
which would increase the current even more.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


Sound like good advice. My calculations were based on all the sources I've
found, but the above makes sense with its safety margins.

A 1/2 watt resistor doesn't get scalding hot, but hot enough. Using a
larger-wattage resistor (such as going to 5-watt) is easy, safer and certainly
cheap!

Scott

Scott...

That is the best eaa site I have visited.

Guessed which was the LED story and read it all.

Good job.

Last week, I attended the farcical FAA-sponsored maintenance seminar and the GE
lighting people were there for the first time.

I had a good discussion with them as to why the Q4509 bulbs burn up when used
continuously as so many do these days (not designed for continuous, and never
tested that way and a surprise that people use them as get out of my way
lights) and they were queried about LED's and the "blue lights" which are such
a pain when on cars.

LED lights are being "looked at".

The blue lights (high intensity discharge) are being evaluated but they have
found too few willing to pay the high prices for it to be a product for
them...yet.

Thanks for the site info and the lead to the article.

Neal

We run LED lights on the Pipistrel Motorgliders,
http://www.pipistrel-usa.com they seem to work really well and are
lower power consumption which is important for gliding. They are made by
BW Avio in Italy www.bwavio.com and have a 4 year gaurantee.



COUGARNFW wrote:
Scott...

That is the best eaa site I have visited.

Guessed which was the LED story and read it all.

Good job.

Last week, I attended the farcical FAA-sponsored maintenance seminar and the GE
lighting people were there for the first time.

I had a good discussion with them as to why the Q4509 bulbs burn up when used
continuously as so many do these days (not designed for continuous, and never
tested that way and a surprise that people use them as get out of my way
lights) and they were queried about LED's and the "blue lights" which are such
a pain when on cars.

LED lights are being "looked at".

The blue lights (high intensity discharge) are being evaluated but they have
found too few willing to pay the high prices for it to be a product for
them...yet.

Thanks for the site info and the lead to the article.

Neal

Glad you guys found this useful.

Our DAR says that they don't make specific demands regarding how something is
done, so LEDs are fine as long as they are bright enough and have the necessary
visibility pattern. He saw no problem whatsoever using LEDs for these lights.

I noted in one of my aviation mags that Whelen has a $700+ vertical stab. LED
strobe light! Probably doesn't include the power supply. This is obscene and
could easily be done with a set of Luxeon 5-watt white LEDs in a circular pattern.

Some 3-rd parties are trying to market various combinations, but unless you need
very special hardware, you can just make these yourself at a fraction of the cost.

Good luck.

Scott

COUGARNFW wrote:

Scott...

That is the best eaa site I have visited.

Guessed which was the LED story and read it all.

Good job.

Last week, I attended the farcical FAA-sponsored maintenance seminar and the GE
lighting people were there for the first time.

I had a good discussion with them as to why the Q4509 bulbs burn up when used
continuously as so many do these days (not designed for continuous, and never
tested that way and a surprise that people use them as get out of my way
lights) and they were queried about LED's and the "blue lights" which are such
a pain when on cars.

LED lights are being "looked at".

The blue lights (high intensity discharge) are being evaluated but they have
found too few willing to pay the high prices for it to be a product for
them...yet.

Thanks for the site info and the lead to the article.

Neal