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Thread: Changing cold cathode backlighting to LEDs (+auto brightness control)

  1. #51
    Join Date
    Dec 2008
    Just took apart my LCD from my old laptop and will be looking to perform a similar replacement. I'm considering using 3mm LEDs instead since size isn't that much of a concern to me (case is broken, so I need a new custom case anyway). If it gets me a sunlight readable monitor, then I'll make a car PC with it.

    Editted: I just tried the above method with some leftover LEDs (both 3mm and 5mm ultra bright LEDs with like 8000 mcd at 3.5V, though I'm only using 3V to power them for this test) and the results were not very good, the old CCFL seems to be better and I think it is that the diffuser for the laptop's LCD is to thin to diffuse all the light throughout(like only 2mm thick).

    I might also try to get wide angled LEDs like the SMD LEDs as internal reflection does most of the work transmitting the light to the LCD?

  2. #52
    Raw Wave
    Join Date
    Nov 2009
    Will backlighting effect sun readability?

    Usually CCFLs provide better lighting due to their wideband dispersion - they can imitate natural lighting etc. Though white LEDs have improved.

  3. #53
    Raw Wave
    Join Date
    Nov 2009
    Sorry Bes - we missed each other.

    Too bothered not to leave a comment?

    So correct in your incorrect earlier posts that you were bothered enough to delete them? Without notification or reason?

    Only you can explain how one string can "rob" another string of current.
    Only you can explain how your referenced paper that describes using junction voltage to measure temperature explains or proves you "LED instability" arguments.
    Only you can explain why a PWM has a current issue.

    You do have the experience don't you?
    Or will you be "word perfect" and blame it on mis-expression?

    I tried to prevent one-hundred odd parallel single LED strings each with resistors.
    I provided a method of controlling dimming that has no voltage-modulation complications.
    You "begged to differ" and then starts a long exchange of replies where I was trying to inform else find out where misunderstanding or knowledge gaps lie.

    I never even got to my original intention which was to explain how to truly dim the CCFLs etc AND thereby decrease their power consumption. (And their effect on the incar 3D LCDs.)

    The cynical would think you were selling LEDs or kits!

    Don't bother with another "Drop it" - as I posted, I dropped before your request. If my expression is so poor that even that was not understood, I apologise, but you have done little to assist.
    But consider this thread dead and unwatched by me.
    Others can use PMs to notify me.

    I shall leave readers and thrill-seekers for the final word from Bes (not that he will be bothered), and his experienced expertise.

  4. #54
    Raw Wave
    Join Date
    Nov 2009
    LOL! Keep trying.
    So why delete your posts - to save space?
    You were the one that kept disagreeing, throwing in diversions, not explaining etc.

    Why not re-post what you said and let others judge?
    (Or I might link to where they can be found if you are unable too.)

    So, one electrical string will rob current from another (non-current controlled circuit)?
    WOW! You must explain to us why the basic laws (ie, Ohm's) fail in this instance.
    Oh - that's right, because of the resistor!

    Maybe you should have gotten your education on the west coast instead....

    My attitude is bad - I try to rectify incorrect knowledge; save people money; provide simpler ans superior solutions.
    That makes me real bad in the eye of those with vested interests, or egomaniacs, etc.

    Change opinion. Nah - I do that often. But it will be difficult to get me to change opinion form V-IR, or that a 12V PWM max current is somehow different to flat 12V DC, or that your LEDs will not tolerate more than 20mA (despite your linked pdf clearly showing currents up to 200mA!).

    More transference, diversion and debunking usually doesn't cut it - except maybe for the gullible. (They have already forgotten else don't understand the significance of my simple questions above. Hey - they might not even now the answers themselves. They've got no hope of understanding how simple solutions can be. They are the sort that think specs are fudged - they do not understand the context of the specs. They think "statistics lie".)

    So it is only you and I that are interested eh. What a waste!
    At least the moderators won't be concerned.
    Normally I wouldn't bother either, but to think that someone was so silly or concerned that they actually deleted their own posts.... Geez - that reminds me of a certain child king (Carl-Gustav? 14th? 17th??), not that anyone would try to censor history of course!

    But this was handed to me on a plate....
    But if this un-subscribe fails yet again, I will be complaining to management about this system!

    Now make sure you do not answer any of my questions.
    Make sure you have the last word. And that will involve the expected personal attacks and debunking of me etc. Don't forget to refer to your years of experience in the field - with the maturity that we are showing in this thread, I'm sure people will underestimate our age and experience.
    One more reply will pay my trip to Täby (oh I miss her). Maybe then you and I could get together and fika. And talk.


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