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"An LED by any other name...

Discussion in 'General Electronics Chat' started by MrAl, Apr 29, 2014.

  1. MrAl

    MrAl Well-Known Member Most Helpful Member

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    would look as bright".

    Or would it?

    There are a million kinds of LED's out there these days, and even the same make and model wont always look the same. Many manufacturers make LED's and 'bin' them into two categories:
    1. Brightness
    2. Color

    By brightness they usually mean the rating appropriate for that LED type (like mcd).
    By color they mean the wavelength, in nanometers.

    There is quite a variance in brightness, where a piece of a certain part number compared to another piece of the same part number could be four times as bright.
    The variance in color is also quite variable, and the bin number for this would indicate where it falls within the color bandwidth specified for that part number.

    A good example, or should i say a bad example, is recently i purchased several yellow LED's, three different part numbers, and one yellow seven segment LED. All of these LED's are not really yellow, they are orangish yellow (yellow but tinted orange).

    I was really after the "lemon yellow" color of another LED i had purchased almost eight years ago. Compared to these other four part numbers, this one looks truly yellow not orange tinted.

    Reading the data sheets for several yellow (and other colors too) LED's i find that the manufacturers *make* LED's that are classified as falling into their several 'bins' for brightness and color (color again referring to the wavelength within that color band such as yellow, not the difference between say red and green or red and yellow). I say *make* like that because although they do make them, they wont sell them that way. In other words, it seems impossible to purchase a lemon yellow LED because they will probably come in as orange tinted yellow, and the manufacturer doesnt care what wavelength the customer gets as long as it is "somewhat" yellow.

    Any ideas how to get the right color, somehow, someday from these companies or their distributors?
     
  2. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Hi MrAl

    Greetings from a soon to be winter South Africa...we are all trying here to keep a good discussion going...and LED's are indeed good :)

    All I know is OSRAM OPTO do not take chances...the E5 is harder to cool than the E3...An E3 with the correct Copper traces does not require any extra stuff..just traces that are the correct width and all is happy. The E3 is a 100mW SMD LED.

    The E5 is another animal altogether. There Osram speak about using Double Sided PCB's. They speak about minature Vias under the the LEDS...they speak about how important it is to cool the LED's. They speak about all heat related stuff...that I am familiar with...

    So, what does tvtech do...Well my PCB's were already Double Sided ..necessary anyway for my little project to be reliable:)
    Why not treat the little E3's too and give them the same treatment...costs nothing more :)

    Result: Little E3's that are the happiest little LEDS in the World. They have their little through plated vias where I think they need them. Like a dream come true for them.

    After more than a Year of testing under the crappiest and worst possible abuse....they still smile at me. As a Team, not one of them has let me down.

    Sorry for making this sound like a Kids book....but I firmly believe that the way to go is to respect Electronic parts...treat them well...and they will treat you well too :) That is why some designs last..and some don't.

    That's it.

    Regards,
    tvtech
     
    Last edited: Apr 30, 2014
  3. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi again,

    Well i was more or less just interested in getting the right color, but yes there are other things we have to pay attention to.

    The lemon yellow colored ones are nicer looking than the orange tinted yellow, and appear brighter because of the color.
    Spiders probably dont like them :)

    I got some pure orange ones too, but they look red orange not strictly speaking orange like an orange peel.
     
  4. dave

    Dave New Member

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  5. tvtech

    tvtech Well-Known Member Most Helpful Member

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    LOL MrAl.

    I am not willing to prove you wrong;)

    Once bitten=twice shy. And remember, these little critters have really good eyesight...
    That spider knew exactly what it was doing when it decided to bite me.

    Hey, I survived though. All that has happened is that I now poison/spray/fumigate anything that vaguely looks like a Spider invading my space.

    Regards,
    tvtech
     
  6. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi,

    Yes ha ha, i mentioned the spider not liking the lemon yellow LED color because it may look like a lemon to a spider, which they dont like, but then again maybe they just dont like the taste of the fruit and have not evolved as far as to be able to associate the color with the fruit. Would be an interesting experiment, as some insects are supposedly attracted to certain color lights more than other colors. It would be very interesting if the spider kept away from the yellow LED but didnt mind the green LED for example, which would just look like a leaf perhaps.

    Anyway, i am sort of particular about my LED colors sometimes because i figure if we want to use an LED for an indicator lamp it should be the color we choose for that particular device. I have found that with the newish modern LED's that we can make AC indicators MUCH easier than in the past because very little current is needed for a high brightness LED to make just an indicator. I've tried 82k for an LED and it works pretty well, and that's with a 10 cent (USD) LED. 82k uses very little power on a 120vac 60 Hz line when driving a single LED at half wave (enough for an indicator). The 120vac appears mostly across the resistor, and with only 1/2 wave per full line cycle the power is around 88mw, and so a half watt resistor stays very cool. That means less than 1 milliamp average through the LED but it does the trick. Used to be we had to use neon bulbs for this job.
     
  7. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Hi MrAl

    Something to do with the smell of it too...I read somewhere that they smell with their feet :wideyed:
    Color will not change their perception of things...

    Anyway...back on topic.

    Good LED's from a reputable supplier could help....here in SA we have http://za.rs-online.com/web/. Pretty good for consistent products.

    Regards,
    tvtech
     
    Last edited: May 1, 2014
  8. alec_t

    alec_t Well-Known Member Most Helpful Member

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    You're lucky. I (like 1 in 7 of the male population, so I understand) have difficulty even distinguishing the light of a red LED from that of a green LED; so I've no chance with lemon-yellow versus other shades of yellow :).
     
  9. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi alec,

    Wow sorry to hear about that, i didnt realize so many were partially color blind.
    Here in the USA they make the traffic lights red and green, but also position them so you can tell which one is on without being able to see the color itself.
     
  10. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Nor did I until I did an optics course at college. Of the 20 students on the course 4 (me included) had defective colour vision! It's a male thing: only ~ 1 in 2000 females suffer from it. I have no problem with traffic lights and large colour areas; it's only if the light source subtends a small angle at the eye (e.g. indicator LEDs at >1 metre). Unfortunately, dual-colour indicator LEDs are usually red-green!
     
  11. ronv

    ronv Well-Known Member Most Helpful Member

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    Then there is yellow by another name.:wideyed:
    There seems to be quite a range:
    Orange, 595nm- super yellow, 592nm - pure yellow, 585nm - yellow, 574nm - lime yellow, green.
    There seems to be a hole where you want it. Must be hard to make a 579 nm LED.
     
  12. kinarfi

    kinarfi Well-Known Member

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    While camping, I did notice the LED light did not seem to attract the flying insects like the Coleman lantern did. Very interesting!!
     
  13. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Hi kinarfi

    Using Duris E3 LED's @ 6500K....no insects..CRI of around 80 to 90. Depending on batch.

    Using the previous Wah Wang...everything outside wanted to come inside and sit on/climb into the light???
    I had Moths, Ants, Flies....trying to camp there???

    Strange stuff. Light and insects have a definite correlation.

    Spiders..another thing altogether:wideyed:

    Regards,
    tvtech
     
    Last edited: May 3, 2014
  14. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hello again,

    alec:
    Sorry to hear about that. My only solution right now is that if you have any red/green dual color LEDs in anything that you swap them out for two new LED's that have the colors you do want, provided the drive voltage is enough to power it of course.
    Most of the green and yellow LED's come in around 2 volts so you could swap out a yellow for green, maybe that would help.
    Another idea is to use two different LED's of any color that can light in that application but separate them from a distance, like even 1/4 inch. One on the left, one on the right, or one up and one down, like they do with traffic lights. That way you can always tell which one is lit. Yes it takes a little work but assuming you dont have that many to swap out you're ok.
    If you dont want to do that maybe you can try a very small prism, where it is mounted to the front of the LED. The different colors will project in different directions, maybe enough to help tell the difference.
    The nice thing is that the red/green or any other multi color LED i've seen has more than one LED mounted at the same horizontal level, so they are spaced apart by some very small distance but some distance nonetheless. That means that for an LED that is permanantly mounted the orientation of the red might be on top, green on bottom, or vice versa, or left and right, or south west and north east, etc, diagonally. You might get someone to tell you which colors are which then note the position so you can always tell.

    ronv:
    Yes, so many colors in the range for yellow makes it hard to get the right color.
    Manufacturers dont seem to want to allow the selection of a given color. Very strange. Their process must not be that accurate.

    kinarfi:
    I have read that some (or maybe all to some degree) insects are attracted to yellow light more than white light, or something like that, and it had to do with food or mating cant remember which now. That means it could help catch the critters or maybe keep them away.
    Brighter light could make a difference too though. A 500 watt light will probably attract more than a 50 watt light for example.

    tvtech:
    Yeah i still havent looked for any data on spiders and light color. Might be interesting though to find out if they have any color sensitivity. If it say Red, we could go out an buy a whole bunch of red LED's and set them up around the house <chuckle>.
    You know what....i bet they dont like any light, or at least prefer little light. Just a guess though because maybe they evolved to realize that insects like light so they should build their home near light too. I have no idea at this point though, just guessing.
     
  15. eTech

    eTech Active Member

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    Hi

    It might not be related to color at all. It might be the "type" of light that draws insects. LEDs are usually Infrared or ultraviolet. I've often seen insects around incandescent lights...

    eT
     
  16. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi eTech,

    Yes that is another avenue to investigate. The bug lamps i've seen have ultraviolet.
     

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