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Making a LED landing light flash

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jerrytex

Joined: 10 Feb 2011
Posts: 12

Posted: Mon Oct 15, 2012 11:53 am Post subject: Making a LED landing light flash

I recently fitted an LED driving light into my wingtip. I am now interested in making it flash so I am more visible in the pattern. What is the best/cheapest way of doing this? I have seen the Wig Wag schematic but I only have one light and from what I read, it requires two lights to work.

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Oct 15, 2012 1:27 pm Post subject: Making a LED landing light flash

At 02:53 PM 10/15/2012, you wrote:

 	  Quote: 	
		  



I recently fitted an LED driving light into my wingtip. I am now 

interested in making it flash so I am more visible in the pattern. 

What is the best/cheapest way of doing this? I have seen the Wig Wag 

schematic but I only have one light and from what I read, it 

requires two lights to work.


	


   Put a 50 ohm resistor in place of the second light.



http://tinyurl.com/9xbhdt6

   Bob . . .

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Mon Oct 15, 2012 4:02 pm Post subject: Re: Making a LED landing light flash

 	  Quote: 	
		  I recently fitted an LED driving light into my wingtip. I am now interested in making it flash so I am more visible in the pattern. What is the best/cheapest way of doing this? I have seen the Wig Wag schematic but I only have one light and from what I read, it requires two lights to work. 	




I have experimented with this and it look like doubling the rate is the best way to go if you have only one lamp. Just leaving out the other lamp leaves a whole lot of empty time to not-be-seen. Try it. You'll like it.



I've made one-lamp flashers for some customers using this method.

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Oct 15, 2012 7:06 pm Post subject: Making a LED landing light flash

At 07:02 PM 10/15/2012, you wrote:

 	  Quote: 	
		  

 > I recently fitted an LED driving light into my wingtip. I am now 

 interested in making it flash so I am more visible in the pattern. 

 What is the best/cheapest way of doing this? I have seen the Wig 

 Wag schematic but I only have one light and from what I read, it 

 requires two lights to work.

I have experimented with this and it look like doubling the rate is 

the best way to go if you have only one lamp. Just leaving out the 

other lamp leaves a whole lot of empty time to not-be-seen. Try it. 

You'll like it.


	


   Agreed. I don't recall the authoritative source but

   waaaayyyy back when, we were advised that cockpit

   warning lights should be flashed at about 3 to

   3.5 flashes per second with 50% duty cycle for

   maximum attention getting effects.



   I was told that's the number that works best for

   intensity modulation (on-off) as opposed to 1 to

   1.5 per second for position modulation (wig-wag).



   Back when I worked with attorneys wrestling with

   grade crossing accidents and various visibility

   issues, we learned that visual acuity for 20/20

   observer was about 1 arc-minute or 1/60th degree.

   To perceive that a wig-wag grade crossing signal

   (8 or 12" roundels on 30" centers) was not a steady

   red light, the 20/20 observer who was paying attention

   under good visibility conditions had to be less

   than 8000' away. For the wig-wag to get some attention,

   required about 3 arc seconds or a sight distance

   of about 2800 feet. Of course, there are a dozen

   other variables that drive the situation down-hill

   from there.



   If your wig-wags are on wing tips of an RV or

   25 feet apart (10x the center distance on a

   grade crossing wig-wag) then you can expect

   pretty good attention grabbing presentation

   in clear visibility to other pilots at about

   28000 feet or 5+ miles and the 1 to 1.5

   transitions/second values apply.



   For intensity modulated warning systems (strobes,

   rotating beacons, etc) the numbers are better

   especially at the faster rate more likely to

   grab attention. Unlike the wig-wag that simply

   morphs into a steady light beyond a certain

   distance, the strobe's on-off behaviors can

   be detected from much greater distances.

   Bob . . .

mrspudandcompany(at)veriz
Guest

Posted: Tue Oct 16, 2012 4:13 am Post subject: Making a LED landing light flash

 	  Quote: 	
		  

   If your wig-wags are on wing tips of an RV or

   25 feet apart (10x the center distance on a

   grade crossing wig-wag) then you can expect

   pretty good attention grabbing presentation

   in clear visibility to other pilots at about

   28000 feet or 5+ miles and the 1 to 1.5

   transitions/second values apply.

   Bob . . .


	


            Are you aware of any wig-wag studies on incondescent vs. LED 

lighting of the same intensity?  I would think that perhaps the LED with 

it's crisp instant on would be an attention getter from a farther distance, 

as opposed to the ramp up of light output from the other source.



What is your take on this?



            Roger

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Oct 16, 2012 5:41 am Post subject: Making a LED landing light flash

Are you aware of any wig-wag studies on incandescent vs. LED lighting 

of the same intensity?  I would think that perhaps the LED with it's 

crisp instant on would be an attention getter from a farther 

distance, as opposed to the ramp up of light output from the other source.



         Not that I'm aware of. My middle son's mother-in-law

         was a professor at KU who spent much of her academic

         career studying the physiology of sight. Were she

         still with us, I'm pretty sure she'd have a lot to

         share . . . and direction to other sources.



         Your mention for rate-of-rise in intensity is

         perceptive. While I was at Cessna, about 1967, a company

         called AeroFlash came out with a replacement for

         the motorized rotating beacons that were the anti-

         collision warning devices of choice in 1965.



         These were single, halogen bulbs under a domed lens

         that delivered the requisite intensity in all directions

         at the same time. But instead of being a 30 watt bulb

         at the center of a mechanical focusing/directing system,

         these were 150 watt devices that were flashed electrically.



         The filaments were so massive that the lamps were visibly

         slower in both rise and fall of intensity than the legacy

         rotating beacon. I remember seeing multiple aircraft at

         night were one was fitted with the AF device while others

         were sporting rotating beacons. The difference in visual

         'force' for getting attention was obvious. But the regs

         for qualifying such devices waxed eloquently about color,

         intensity, flash rates and spherical coverage without the

         slightest attention to rate of rise/fall for the emitted

         energy.



         I went to the bench last night an cobbled up a panel

         mounted, incandescent annunciator light to renew my

         recollected perceptions for flash rate and duty cycle.

         The rise/fall characteristics of the incandescent lamp

         was perceptible and my anecdotal musings with the knobs

         on the function generator renewed and old bit of knowledge

         that a 33% on 66% off was a bit more 'forceful' when

         observed in peripheral vision. An LED substitute didn't

         seem to have much difference at 33/66 vs 50/50.



         My gut feeling is that lights which are flashed will

         probably rattle the grey matter of distant pilots sooner

         than lights which are simply wig-wagged. LED's are no doubt

         better yet. Perhaps the ideal system would not only

         alternate the lamps from side to side  . . . but

         generate a trio of pulses for each illumination. Say

         3 flashes in 1 second per side. I think I recall a

         system being offered at OSH over 10 years ago for

         producing a series of short flashes for each illumination

         interval. Again, the rise/fall rates for LED's would

         probably enhance performance.



         That's something we could do with the LED wig-wag

         project. The software could be modified to offer the

         trio of short bursts for each lamp in addition to the

         positional offset of side-to-side cycling.



         That project is not on a back burner. I've got boards

         laid out and thanks to the able skills of byte-herder

         McHugh, we have source code that could easily be amended

         to produce the proposed behavior. All I need is a 36-hour

         day . . . but it's going to happen along with several other

         new products.

   Bob . . .

raymondj(at)frontiernet.n
Guest

Posted: Tue Oct 16, 2012 6:37 am Post subject: Making a LED landing light flash

Just a random thought. How would what I'll call "asynchronous wig wag" 

affect visual impact? The flash pattern I'm thinking of would have 

wingtips flashing at different rates. As an example, the left flashing 

at 1/sec and the right at 1/1.25 sec. Or each one flashing at random 

intervals between 1/.5 sec and 1/1.5sec.



Any thoughts, experience, or data.



do not archive



Raymond Julian

Kettle River, MN.



"And you know that I could have me a million more friends,

and all I'd have to lose is my point of view." - John Prine



On 10/16/2012 08:40 AM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 Are you aware of any wig-wag studies on incandescent vs. LED lighting 

 of the same intensity? I would think that perhaps the LED with it's 

 crisp instant on would be an attention getter from a farther distance, 

 as opposed to the ramp up of light output from the other source.



 Not that I'm aware of. My middle son's mother-in-law

 was a professor at KU who spent much of her academic

 career studying the physiology of sight. Were she

 still with us, I'm pretty sure she'd have a lot to

 share . . . and direction to other sources.



 Your mention for rate-of-rise in intensity is

 perceptive. While I was at Cessna, about 1967, a company

 called AeroFlash came out with a replacement for

 the motorized rotating beacons that were the anti-

 collision warning devices of choice in 1965.



 These were single, halogen bulbs under a domed lens

 that delivered the requisite intensity in all directions

 at the same time. But instead of being a 30 watt bulb

 at the center of a mechanical focusing/directing system,

 these were 150 watt devices that were flashed electrically.



 The filaments were so massive that the lamps were visibly

 slower in both rise and fall of intensity than the legacy

 rotating beacon. I remember seeing multiple aircraft at

 night were one was fitted with the AF device while others

 were sporting rotating beacons. The difference in visual

 'force' for getting attention was obvious. But the regs

 for qualifying such devices waxed eloquently about color,

 intensity, flash rates and spherical coverage without the

 slightest attention to rate of rise/fall for the emitted

 energy.



 I went to the bench last night an cobbled up a panel

 mounted, incandescent annunciator light to renew my

 recollected perceptions for flash rate and duty cycle.

 The rise/fall characteristics of the incandescent lamp

 was perceptible and my anecdotal musings with the knobs

 on the function generator renewed and old bit of knowledge

 that a 33% on 66% off was a bit more 'forceful' when

 observed in peripheral vision. An LED substitute didn't

 seem to have much difference at 33/66 vs 50/50.



 My gut feeling is that lights which are flashed will

 probably rattle the grey matter of distant pilots sooner

 than lights which are simply wig-wagged. LED's are no doubt

 better yet. Perhaps the ideal system would not only

 alternate the lamps from side to side . . . but

 generate a trio of pulses for each illumination. Say

 3 flashes in 1 second per side. I think I recall a

 system being offered at OSH over 10 years ago for

 producing a series of short flashes for each illumination

 interval. Again, the rise/fall rates for LED's would

 probably enhance performance.



 That's something we could do with the LED wig-wag

 project. The software could be modified to offer the

 trio of short bursts for each lamp in addition to the

 positional offset of side-to-side cycling.



 That project is not on a back burner. I've got boards

 laid out and thanks to the able skills of byte-herder

 McHugh, we have source code that could easily be amended

 to produce the proposed behavior. All I need is a 36-hour

 day . . . but it's going to happen along with several other

 new products.

 Bob . . .

FisherPaulA(at)johndeere.
Guest

Posted: Tue Oct 16, 2012 9:25 am Post subject: Making a LED landing light flash

I'm glad to hear the wig-wag project isn't on the back burner.  I tried, unsuccessfully, to get involved back in May/June but apparently higher priority projects moved in.  I'd still be interested once you get that 36 hour day thing figured out!  



I have no pressing need - it just sounds like an interesting learning opportunity...



Paul A. Fisher 

RV-7A N18PF

Q200 N17PF  



--

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Oct 16, 2012 10:28 am Post subject: Making a LED landing light flash

At 12:24 PM 10/16/2012, you wrote:

 	  Quote: 	
		  

<FisherPaulA(at)johndeere.com>



I'm glad to hear the wig-wag project isn't on the back burner.  I 

tried, unsuccessfully, to get involved back in May/June but 

apparently higher priority projects moved in.  I'd still be 

interested once you get that 36 hour day thing figured out!  


	


    Oh yeah, you asked for a board. I can send

    you one along with a copy of Greg's present

    handiwork. Shoot me an address again.



    How's your stock of 1206 SMD parts? I can

    probably put sort of a 'kit' together.



    Have you downloaded the latest data package?



http://tinyurl.com/6w9vndk



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Oct 16, 2012 12:01 pm Post subject: Making a LED landing light flash

At 12:24 PM 10/16/2012, you wrote:

 	  Quote: 	
		  

<FisherPaulA(at)johndeere.com>



I'm glad to hear the wig-wag project isn't on the back burner.  I 

tried, unsuccessfully, to get involved back in May/June but 

apparently higher priority projects moved in.  I'd still be 

interested once you get that 36 hour day thing figured out!  


	


    Oh yeah, you asked for a board. I can send

    you one along with a copy of Greg's present

    handiwork. Shoot me an address again.



    How's your stock of 1206 SMD parts? I can

    probably put sort of a 'kit' together.



    Have you downloaded the latest data package?



http://tinyurl.com/6w9vndk



========================================



    SCRATCH THE ABOVE. I'd promised you a STUFFED

    board. Also found your address. The board is about

    half done. Won't make today's pickup but it will go

    out tomorrow. I'll find Greg's last pass on the

    code and get it posted to the website.

   Bob . . .

FisherPaulA(at)johndeere.
Guest

Posted: Wed Oct 17, 2012 5:57 am Post subject: Making a LED landing light flash

Thanks Bob.  I'll take a look and see if I can incorporate a 3-flash on cycle for the transition of the wig-wag into Greg's software and get it back to the group.  Should be an interesting project!



 - Paul

--

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Oct 17, 2012 6:42 am Post subject: Making a LED landing light flash

At 08:56 AM 10/17/2012, you wrote:

 	  Quote: 	
		  

<FisherPaulA(at)johndeere.com>



Thanks Bob.  I'll take a look and see if I can incorporate a 3-flash 

on cycle for the transition of the wig-wag into Greg's software and 

get it back to the group.  Should be an interesting project!


	


    I think so.



    One of the things I miss most about being 'retired' is

    that it's more like being 'isolated'. Most of the jobs

    I've held came with a certain population of curious minds

    who were also great 'connectors of dots' . . . they

    could sit around a table and play 'pass the idea' . . .

    each trip around the loop would produce clearer insight

    and/or interesting alternatives to the task before us.

    While working in the Targets division at HBC, I sat in

    a bull-pen of cubicles occupied by such individuals. We

    overheard each other's conversations including phone calls.

    A GOOD thing especially when some eavesdropper had some

    interesting thought or fact to stir into the mix.



    You folks are my surrogate think tank. I'm enthusiastic

    about exploring these 'open source' projects. In terms

    of quality of outcome, it cannot be bad . . . and certainly

    much better than projects that grow up within narrow silos

    of talent and responsibility.



    When I've explained these experiments with some of my

    past colleagues, they often voice some skepticism about

    the 'business model'. Over the years, I've come to understand

    that product development is greatly separated from production

    and marketing of an idea. Further, just because an idea is

    fully disclosed doesn't mean that there is an increased risk

    to individuals who decide to produce and market those ideas.



    Most of the folks on the List have no interest in producing

    and marketing anything. They're interested in acquiring

    certain capabilities, of good value, off the shelf with track

    record and warranty. If competing production and marketing efforts

    arise from an idea, it's a good thing. Carrying these activities forward in

    the open source, open forum environment goes a long way toward

    informing potential customers and demonstrating track records.



    But for some, it's not about production/marketing. It's all

    about an intellectual 'buzz' that rises from a successful

    recipe of of simple ideas. During my brief stint in television

    broadcast, I was tasked with producing and marketing a video

    time base corrector. The thing was designed by a very clever

    fellow who was deprived of the 'think tank' refinement tools

    that I've learned to value. I was forced into learning video

    in a big hurry so that I could sift out the little bugs and

    production snags in the design. Support from the original

    designer was disappointing. He'd seen it work once and was

    off on other ideas. He ultimately went to work for Heathkit,

    the IDEAL environment for his talent and motivations. He was

    immersed in an organization of very capable production and

    marketing folks who could maximize the exploitation of his

    unique talents.



    I'd like to believe that the List membership includes the

    whole spectrum of talents, personalities and life-goals

    willing to contribute to the life cycle of interesting and

    useful products.



    We shall see. Thanks for participating . . . any many thanks

    to those who have participated thus far.

   Bob . . .

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Thu Oct 18, 2012 3:09 pm Post subject: Re: Making a LED landing light flash

Some notes on wig wags and flashers: This field has been studied since the 1800's since people were quite interested in making lighthouses visible to ships. Studies on what is most visible and how it is measured is an extremely difficult subject: Viz, a light visible at a flash pulse-width of 40 mS can appear to be LESS BRIGHT at 50 mS. WTF? (I hear you ask), well, the visual system is working as hard as it can to detect a shorter flash and sends a signal to the brain. Nothing happens beyond that while the visual neurons need time to recover. OR SOMETHING...Weird. (Broca & Sulzer 1902). I'm not sure anyone really knows, but it is an easy experiment to reproduce.



Blondel-Rey equations are used to determine Effective Intensity Ie. In the last few years the methodology has been called into question because the Blondel-Rey equations don't work well except with purely square-wave pulses over a limited range. The B-R equations don't do so well with strange wave shapes, multiple flashes, complex flash chains, and many other complications. Nevertheless the FAA still uses B-R. 



The Cessna beacon was approved years ago and still complies with the old standard. The new FAA standard (which YOU must use) is much brighter.



The best reason to use LEDs for brake lights is that the distance you have available to stop when the guy in front of you stops is markedly increased due to not having the delay needed to heat up a tungsten lamp, so you see it sooner. This is much safer but probably has nothing to do with the wave shape and wouldn't help much in aviation.



An LED engineer suggested to me that I use the newest board-mounted red LEDs because they can produce much higher-energy flashes (or even Ie) than white (or anything else). I intend to do so.



Attached is my paper on LED beacons. The last couple paragraphs show their age. These beacons are easier and cheaper than they were 8 years ago.



Comments appreciated.

aircraft_beacons_using_leds.pdf

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_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

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