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Thread: led ring light

  1. #61

    Default Re: led ring light

    Quote Originally Posted by DeSwitch
    isit? see how i lag behind in technology liao.

    Haha. Serious, can those work and do they have white colour?
    haha...neon light is quite bright...but if gona use neon light mus gt reflector similar to a torch light....n neon light do ve white...but duno where can get it...

    color chart of neon light
    http://www.neon-lighting.com/neon-colors.htm
    Last edited by dreamerz; 28th March 2006 at 07:26 PM.
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  2. #62
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    Default Re: led ring light

    Quote Originally Posted by ortega
    looking to make this?

    http://www.srelectronics.com/Lring.html

    i saw it at the IT SHow
    from the same co that displays the tamron lenses

    Otega, did you test them out during the IT show? I missed it cos I was shooting Models .

    Whats the price range?

    TIA

  3. #63

    Default Re: led ring light

    Quote Originally Posted by dreamerz
    haha...those are neon light lar...nt fluroscent...
    If it's white colour, it's probably fluorescence. Neon only glows orange-red. It has to do with the gas's ionising spectra line which is mainly monochromatic. I think people just conveniently calls them neon lights.
    Last edited by lsisaxon; 29th March 2006 at 10:15 AM.

  4. #64

    Default Re: led ring light

    An idea.
    Instead of using LEDs, how about defraction glass plus 20 laser pointers?
    Defract and diffuse the laser by a few degrees, sure it will give better ranges.

  5. #65

    Default Re: led ring light

    Quote Originally Posted by dRebelXT
    An idea.
    Instead of using LEDs, how about defraction glass plus 20 laser pointers?
    Defract and diffuse the laser by a few degrees, sure it will give better ranges.
    Wah.. what you want to shoot? holograms? Anyway, lasers are monochromatic also.

  6. #66

    Default Re: led ring light

    Aren't most laser pointers are red? Doubt it is useful in this case.

  7. #67

    Default Re: led ring light

    Quote Originally Posted by thomas_lkt
    Aren't most laser pointers are red? Doubt it is useful in this case.
    Well.. there are green ones too. .. but they're still useless..
    Last edited by lsisaxon; 29th March 2006 at 11:58 PM.

  8. #68
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    Default Re: led ring light

    Quote Originally Posted by lsisaxon
    Well.. there are green ones too. .. but they're still useless..
    If the blue laser available.... .

    Red, Green, Blue ==> White laser... .

    Regards,
    Arto.

  9. #69
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    Default Re: led ring light

    Lasers even if there is white light will be useless because the beam is only a point. I'm relooking into my project by adding more Leds and custom made an aluminium ring with chamfered LEDs holes to reflect the light. I search the web and found some interesting similar project. There was a dentist making one for his work useage. His LED were arranged at an angle.

    He had the same problem in his 1st attempt, not enough light output so his second attempt which he had not completed (I think) will use around 78 LEDs as mention in his post.

  10. #70
    vince123123
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    Default Re: led ring light

    Wow, aluminium ring? I'd be intersted as I think it would suit my project to make a reading light.

    By the way, can you share the link on this project by the dentist?

    Also, the super bright LEDs you used for the first project - how much was the cost per LED?

    Quote Originally Posted by DeSwitch
    Lasers even if there is white light will be useless because the beam is only a point. I'm relooking into my project by adding more Leds and custom made an aluminium ring with chamfered LEDs holes to reflect the light. I search the web and found some interesting similar project. There was a dentist making one for his work useage. His LED were arranged at an angle.

    He had the same problem in his 1st attempt, not enough light output so his second attempt which he had not completed (I think) will use around 78 LEDs as mention in his post.

  11. #71
    Moderator ortega's Avatar
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    Default Re: led ring light

    Quote Originally Posted by DeSwitch
    Otega, did you test them out during the IT show? I missed it cos I was shooting Models .

    Whats the price range?

    TIA
    yes i tested it, but only took a picture of a catalog
    the multiple highlights were not very nice

    it might be different on other surfaces
    personally i would not buy it for a DSLR use
    there was a ring flash on display as well
    the results were better than the LED light

    Ring Flash was above $100 and below $200 - Show Price

  12. #72
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    Default Re: led ring light

    Quote Originally Posted by ortega
    yes i tested it, but only took a picture of a catalog
    the multiple highlights were not very nice

    it might be different on other surfaces
    personally i would not buy it for a DSLR use
    there was a ring flash on display as well
    the results were better than the LED light

    Ring Flash was above $100 and below $200 - Show Price

    Thank Otega.


    vince123123, The Super bright LED cost S$1 each at Sim Lim Tower. I search for the link and post later.

    The Link
    Last edited by DeSwitch; 30th March 2006 at 11:06 AM.

  13. #73
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    Default Re: led ring light

    Mind if i comment about the circuitry?

    1) by connecting the LEDs in parallel, is a voltage drop of 3x1.5V across all the LEDs...
    2) LEDs are driven by current, not voltage.
    3) without a resistor in the circuit... chances are your LEDs will keep blowing..
    V = IR, fixed V, low R, I will be too high.
    4) use too many LEDs, 3 batteries is cannot provide sufficient current.
    V = IR, fixed V, high R, I will be too low.

    8 LEDs should be enough to light up quite brightly.. 12 should be more than enough. but first, I think you need to find the current needed to light up each LED, and subsequently calculate the number of batteries/LEDs optimal for usage.

  14. #74
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    Default Re: led ring light

    Quote Originally Posted by DeSwitch
    I just connect them up in parallel. My 1st intention was to make it with 2 intensity, hence I alternate the LEDs into 2 loops os the connection is quite messy. Here is a simplier diagram. Hope you can see it cos I cut and paste from my ACAD drawing. make sure the polority of theLEDs are correct.

    Ok there's a problem with this circuit.
    You need to cut the loop created in this circuit.
    It may work, but it will not be optimal.

    but beware, without a proper resistor in your circuit, highly likely you're going to blow your LEDs...
    Last edited by unseen; 30th March 2006 at 11:20 PM.

  15. #75

    Default Re: led ring light

    Quote Originally Posted by unseen
    Mind if i comment about the circuitry?

    1) by connecting the LEDs in parallel, is a voltage drop of 3x1.5V across all the LEDs...
    2) LEDs are driven by current, not voltage.
    3) without a resistor in the circuit... chances are your LEDs will keep blowing..
    V = IR, fixed V, low R, I will be too high.
    4) use too many LEDs, 3 batteries is cannot provide sufficient current.
    V = IR, fixed V, high R, I will be too low.

    8 LEDs should be enough to light up quite brightly.. 12 should be more than enough. but first, I think you need to find the current needed to light up each LED, and subsequently calculate the number of batteries/LEDs optimal for usage.
    1) Why 3x1.5V?
    2) White LEDs need to have a forward voltage, Vf, of about 4V to light up properly. About 20mA of current is sufficient to achieve typical brightness.
    3) All the LEDs will blow, in turn, after some time. The first to blow will be the one with the lowest Vf.
    4) Batteries can supply the current, just that it would not last long.

  16. #76
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    Default Re: led ring light

    hmmm now that i read back, i guess i must be dreaming.. LOL i also wonder why 3x1.5v
    Think i was spouting rubbish.. lol.. sorry.. lack of sleep and the trauma of having to redo half my FYP report..

    I think
    1) not potential drop, but potential difference..
    2) Anyway I was pouring over a RS and Farnell catalogs.. forward voltage for most of the white LEDs is 3.5V, some 3.4V, some 3.6V.. But yeah.. I think i shld haf phrased it as need to watch the current required. Having enough Voltage does not mean there's enough current to light up the LEDs..
    3) Yups.. path of least resistance goes 1st.. LOL there's always a chance that the LEDs are equally balanced..
    4) I stand corrected. Thanks..

    Anyway for each LED should use 1 resistor...
    the resistance of each being
    (Vsource -VdropacrossLED)/(IacrossLED * no. of LEDs)

  17. #77

    Default Re: led ring light

    Use some form of LED driver to "regulate" the power output might help to reduce LED casualty

  18. #78

    Default Re: led ring light

    Usually LED drivers are just some of power regulator. And they still need a resistor as a current regulating device.
    Therefore, save some money and use a resistor.

  19. #79

    Default Re: led ring light

    Quote Originally Posted by DeSwitch
    I already tried 20 pieces of the so called super bright LED and only gives a light like a night lamp. You may need about 80 to 100 pieces to get decent level of light. One point I forgot to mention is that the "white" LED are slightly bluish tinted. so all photos need to be post processed for colour correction. Not I'm think of making 2 side mounted light with the LEDs. (Like Canon MT-24EX)

    I saw another guy making this ring flash in another site.

    http://panchoskywalker.skyblog.com/
    i think u may have got the "cheaper" version of white LED. most super-bright white led u find in slt is slightly blueish. the better version (if u get from rs/farnell) is pure white. i think the pure white version cost $1.50 each when i asked at slt 2 years back, but quite hard to find

  20. #80

    Default Re: led ring light

    Quote Originally Posted by unseen
    hmmm now that i read back, i guess i must be dreaming.. LOL i also wonder why 3x1.5v
    Think i was spouting rubbish.. lol.. sorry.. lack of sleep and the trauma of having to redo half my FYP report..

    I think
    1) not potential drop, but potential difference..
    2) Anyway I was pouring over a RS and Farnell catalogs.. forward voltage for most of the white LEDs is 3.5V, some 3.4V, some 3.6V.. But yeah.. I think i shld haf phrased it as need to watch the current required. Having enough Voltage does not mean there's enough current to light up the LEDs..
    3) Yups.. path of least resistance goes 1st.. LOL there's always a chance that the LEDs are equally balanced..
    4) I stand corrected. Thanks..

    Anyway for each LED should use 1 resistor...
    the resistance of each being
    (Vsource -VdropacrossLED)/(IacrossLED * no. of LEDs)
    Typical white LED forward voltage ranges from 3.4~3.8V. For design purpose, you'll use a higher voltage just to ensure you get the optimal brightness.

    If you are calculating the resistor value for a single LED, the denominator should just be IacrossLED, no need to multiply by number of LEDs.
    Even if you connect a few LEDs in series, the denominator will still be IacrossLED only.

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