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LED Strobe Question for Bob Nuckolls

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rgf(at)dcn.davis.ca.us
Guest

Posted: Sat Feb 28, 2009 7:05 pm Post subject: LED Strobe Question for Bob Nuckolls

Hello Bob,



I have your 1000ma AEC9051 filtered BuckPuck and some Luxeon Star III and

Rebel Star LEDs (http://www.luxeonstar.com/). Also downloaded and read

through the various data sheets for your filtered setup, the BuckPucks, and

the Luxeon LEDs.  The BuckPuck used in your AEC9051 is the -E model,

external control, which allows the output--and thus the LED--to be switched

on and off. The BuckPuck datasheet even has several simple circuit diagrams

showing how to reduce the current and set up strobed LEDs...but lacking in

their diagrams and my head is any knowledge of how to make a strobe (pulse)

logic circuit.



I'm thinking that the brightest neutral white LEDs (e.g. Endor Rebel - Cool

White, Tri-Emitter, 435 Lumens (at) 700mA

http://www.luxeonstar.com/endor-rebel-cool-white-triemitter-435-lumens-700ma

-p-179.php), if pulsed, could substitute for a traditional gas tube strobe.

But it would need a logic circuit to pulse the BuckPuck control signal in a

strob-ish fashion...single, double, or triple wink, etc.  Would you care to

design such a circuit and post?  And maybe, if demand exists, offer it

builtin to your AEC9051s.



Thanks for reading--

Ralph Finch

Davis CA

RV-9A QB and slow-build

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 01, 2009 12:27 pm Post subject: LED Strobe Question for Bob Nuckolls

At 09:03 PM 2/28/2009, you wrote:

 	  Quote: 	
		  



Hello Bob,



I have your 1000ma AEC9051 filtered BuckPuck and some Luxeon Star III and

Rebel Star LEDs (http://www.luxeonstar.com/). Also downloaded and read

through the various data sheets for your filtered setup, the BuckPucks, and

the Luxeon LEDs.  The BuckPuck used in your AEC9051 is the -E model,

external control, which allows the output--and thus the LED--to be switched

on and off. The BuckPuck datasheet even has several simple circuit diagrams

showing how to reduce the current and set up strobed LEDs...but lacking in

their diagrams and my head is any knowledge of how to make a strobe (pulse)

logic circuit.



I'm thinking that the brightest neutral white LEDs (e.g. Endor Rebel - Cool

White, Tri-Emitter, 435 Lumens (at) 700mA

http://www.luxeonstar.com/endor-rebel-cool-white-triemitter-435-lumens-700ma

-p-179.php), if pulsed, could substitute for a traditional gas tube strobe.

But it would need a logic circuit to pulse the BuckPuck control signal in a

strob-ish fashion...single, double, or triple wink, etc.  Would you care to

design such a circuit and post?  And maybe, if demand exists, offer it

builtin to your AEC9051s.


	


    We could do that. The question to be explored is whether or not

    any combination of LEDs driven by a 1000mA Buck-Puck provides

    adequate intensity to (1) be a useful anti-collison attention

    getter and (2) satisfy requirements levied upon us by FAR91.205



    I saw LED anti-collision products from the likes of Whelen,

    Grimes, et. als. that circulated through the halls of Hawker-Beech

    for probably the last ten years. They all went to the notion of

    offering "approved" anti-collision lighting. I've not followed the

    evolution of those products as they were never part of my work

    assignment. But the last examples I saw were fitted with large

    arrays (dozens) of LED emitters.



    Of course, this technology is moving ahead at break-neck

    speed and I would not be surprised if components now exist

    that would make your suggestion practical. But the configuration

    of devices to provide both intensity and spherical spread

    of emissions needs to be addressed first. Doing electronics

    to drive it will be easy.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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rv(at)thelefflers.com
Guest

Posted: Sun Mar 01, 2009 1:47 pm Post subject: LED Strobe Question for Bob Nuckolls

25.1401 Anti-collision Lights states:



f) Minimum effective intensities for anticollision lights. Each

anticollision light effective intensity must equal or exceed the applicable

values in the following table. 

------------------------------------------------------------

Effective

Angle above or below the horizontal plane      intensity

(candles)

------------------------------------------------------------

0° to 5°........................................     400

5° to 10°.......................................     240

10° to 20°......................................      80

20° to 30°......................................      40

30° to 75°......................................      20

------------------------------------------------------------



I wouldn't think that would be too difficult to do with Luxon Star IIIs.

Nova was able to get 660+ lumens with just 4 LEDs.



--

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 01, 2009 2:29 pm Post subject: LED Strobe Question for Bob Nuckolls

At 03:50 PM 3/1/2009, you wrote:

 	  Quote: 	
		  



25.1401 Anti-collision Lights states:



f) Minimum effective intensities for anticollision lights. Each

anticollision light effective intensity must equal or exceed the applicable

values in the following table.

------------------------------------------------------------

Effective

Angle above or below the horizontal plane      intensity

(candles)

------------------------------------------------------------

0° to 5°........................................     400

5° to 10°.......................................     240

10° to 20°......................................      80

20° to 30°......................................      40

30° to 75°......................................      20

------------------------------------------------------------


	


    Keep in mind that these are contiguous coverage values

    measured on a circle. Unlike the helical gas filled tubes

    or even the halogen lamps of the old AeroFlash lights,

    the LED tends to be pretty directional with the rated

    output being measured on maximum output axis.



    See:



http://www.philipslumileds.com/technology/radiationpatterns.cfm



    So the trick is to select an array of emitters and

    position them so that their patterns overlap to

    offer the light levels cited above wherein you can

    do a spherical study of the entire dome above the

    fixture and get readings that comply with the

    numbers in the chart.



    This could easily take dozens of emitters . . .

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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dilandl

Joined: 28 Dec 2007
Posts: 7
Location: Madison Alabama

Posted: Sun Mar 01, 2009 3:35 pm Post subject: LED Strobe Question for Bob Nuckolls

Unfortunately, one rebel isn't even close to the required candela for a 

compliant strobe.  To meet the the most stressing effective candela 

requirement (400 over an elevation range of +- 5 degrees) you really 

need a peak intensity of at least 600 candela over these angles.  This 

is because the FAA's definition of effective candela is a function of 

the duration of the flash and it works out that you generally wouldn't 

want a flash duration of more than about 400 msecs and you would really 

rather have less.  The flash duration of your typical xeon flash tube is 

much much shorter than that.  At some point it becomes a "blink" instead 

of a "flash".  At any rate,  I have been working with a setup that uses 

12 of these rebels arranged in a 1" circle and pulsed at 1 amp.  This 

measured out at well over 750 candela on axis but the problem is that 

because of the lambertian distribution pattern of these LED's, the 

intensity falls off as you move off axis.  At +- 60 degrees off axis, 

your down to about 1/2 the intensity which in this case is about 375 

candela.  A typical setup using 2 wingtip lights and one tail light has 

each wingtip light covering 110 degrees of azimuth and the tail light 

covering the remaining 140 to get the total 360 degrees around the 

aircraft.  Now I believe that with the proper use of some reflectors to 

focus the output into the angles where its needed that this setup has 

enough output to meet the specs over a 110 to 140 degree azimuth - but 

that's with 12 of these devices!  This could be driven with 4 BuckPucks 

controlled with a single Microchip PIC - in fact, that is the setup I 

used in my initial fiddling with these things.  There is a diagram of 

how to hook this up in the BuckPuck documentation.  The hardware is bone 

simple, but of course you now get to provide the functionality via 

software on the PIC.  Pick your poison - hardware or software!  I took 

the software route because it's much easier to change or tweak the 

functionality by modifying the code than by changing hardware.



There is a reason the market is not just covered up with LED aviation 

anti collision lights - it's hard to do!

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 09:03 PM 2/28/2009, you wrote:

> 

> <rgf(at)dcn.davis.ca.us>

>

> Hello Bob,

>

> I have your 1000ma AEC9051 filtered BuckPuck and some Luxeon Star III 

> and

> Rebel Star LEDs (http://www.luxeonstar.com/). Also downloaded and read

> through the various data sheets for your filtered setup, the 

> BuckPucks, and

> the Luxeon LEDs.  The BuckPuck used in your AEC9051 is the -E model,

> external control, which allows the output--and thus the LED--to be 

> switched

> on and off. The BuckPuck datasheet even has several simple circuit 

> diagrams

> showing how to reduce the current and set up strobed LEDs...but 

> lacking in

> their diagrams and my head is any knowledge of how to make a strobe 

> (pulse)

> logic circuit.

>

> I'm thinking that the brightest neutral white LEDs (e.g. Endor Rebel 

> - Cool

> White, Tri-Emitter, 435 Lumens (at) 700mA

> http://www.luxeonstar.com/endor-rebel-cool-white-triemitter-435-lumens-700ma 

>

> -p-179.php), if pulsed, could substitute for a traditional gas tube 

> strobe.

> But it would need a logic circuit to pulse the BuckPuck control 

> signal in a

> strob-ish fashion...single, double, or triple wink, etc.  Would you 

> care to

> design such a circuit and post?  And maybe, if demand exists, offer it

> builtin to your AEC9051s.



    We could do that. The question to be explored is whether or not

    any combination of LEDs driven by a 1000mA Buck-Puck provides

    adequate intensity to (1) be a useful anti-collison attention

    getter and (2) satisfy requirements levied upon us by FAR91.205



    I saw LED anti-collision products from the likes of Whelen,

    Grimes, et. als. that circulated through the halls of Hawker-Beech

    for probably the last ten years. They all went to the notion of

    offering "approved" anti-collision lighting. I've not followed the

    evolution of those products as they were never part of my work

    assignment. But the last examples I saw were fitted with large

    arrays (dozens) of LED emitters.



    Of course, this technology is moving ahead at break-neck

    speed and I would not be surprised if components now exist

    that would make your suggestion practical. But the configuration

    of devices to provide both intensity and spherical spread

    of emissions needs to be addressed first. Doing electronics

    to drive it will be easy.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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_________________
Dan Langhout
Madison, AL
RV-7 in progress

rgf(at)dcn.davis.ca.us
Guest

Posted: Sun Mar 01, 2009 4:57 pm Post subject: LED Strobe Question for Bob Nuckolls

My comments are interspersed in the quoted message:



[quote] --

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