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  1. #1
    25+ Posting Member jonnydaz53's Avatar
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    Fmc Led Backlighting Help !

    hi all need a some advice regarding backlighting for my opencockpits fmc.

    Im using the output card from opencockpits which gives 50 volts per output and 500 ma. And i need to run around 20 x 3mm or 5mm leds for backlighting . Can anyone tell me what leds i should buy (as in votages) and resistors plus how i should wire them serial or parallel and how many outputs to use .

    Im a novice with this.

    thanks


    jonny d

  2. #2
    25+ Posting Member jonnydaz53's Avatar
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    any idea,s anyone?

  3. #3
    300+ Forum Addict mpl330's Avatar
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    Hi,

    Maybe this could help?
    http://led.linear1.org/led.wiz

    Cheers
    Mike

  4. #4
    25+ Posting Member salautom's Avatar
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    Hello Jonny,

    maybe jou can have a look at:
    http://www.hebeiltd.com.cn/?p=zz.led...tor.calculator

    but why are you using the output card for backlighting?
    why not using 12V from a PC powersupply?

    I use bright green leds for my cdu backlighting (see my site, pictures)
    the leds I use have a voltage drop of 3.8V so I connect 2 leds in series with a resistor of 220 ohm, you can connect several of these combinations parallel to your powersource.

    resistor calculation:
    powersource 12V - (2 x 3.8V drop) = 4.4V
    divide that by the led amp (usualy 20mA), this gives you 220 ohm as a resistor.
    Regards,

    Henk.

    (my hobby: http://777simulator.nl)
    (FSX/Sim-Avionics/OpenCockpits)

  5. #5
    25+ Posting Member jonnydaz53's Avatar
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    thanks for the reply the reason i was going to use the output card is because i thought if i connect all the backlighting this way i can control the dimming of the light through the software ie sioc.

    what do you think?

  6. #6
    Boeing 777 Builder


    Kennair's Avatar
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    Quote Originally Posted by jonnydaz53 View Post
    hi all need a some advice regarding backlighting for my opencockpits fmc.

    Im using the output card from opencockpits which gives 50 volts per output and 500 ma. And i need to run around 20 x 3mm or 5mm leds for backlighting . Can anyone tell me what leds i should buy (as in votages) and resistors plus how i should wire them serial or parallel and how many outputs to use .

    Im a novice with this.

    thanks


    jonny d
    Jonny, I've just bought a pack of 100 super bright 5mm LED's from HERE. Very cheap and plenty of them. And as already mentioned, no need to waste your output card just use a 12v power pack with resistors For a good example of the building process and resistor calculations have a look HERE.

    EDIT. I just read your previous reply. Yes the ability to adjust brightness via SIOC is a good one and in fact used by Opencockpits with their backlit EFIS unit. Just be mindful that given the number of LED's you need to backlight a panel, you'll quickly reach the limit of outputs on the card. If you're using it just for the FMC then you're fine.

    Ken.
    Opencockpits | Aerosim Solutions | Sim-Avionics | P3D | FDS | FTX | AS16 | PPL | Kennair


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