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  1. #1
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    Baclight pael with arduino

    Hi there
    I started to think about a back light for my CO/NAV MP panel,as I'm using arduino for all the encoders switches and LCD it was natural to think how to connect all those LED's from back light to arduino.
    Now I need about 30 of them and I don't want t use transistor or anything additional.
    I read that on arduino mega you can pull 800mA,but I read elsewhere that you should stick to 200mA for the whole board.
    So any idea how and if possible,connect 30 LED to arduino mega?

  2. #2
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    Re: Baclight pael with arduino

    I realize you don't want to use anything additional, however, a better (and very simple) option would be the of use of a ULN 2803 chip; it can sink up to 500mA while only using one arduino output to turn on the back-light. These chips can cost anywhere from $0.50 to $1.50. I use one to drive a stepper motor and it works great - and it's simple to interface. This chip has been included in my design to drive back-lighting and other functions.

    To see an example, refer to the bottom of the page of this link.

    Hope this helps.

  3. #3
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    Re: Baclight pael with arduino

    Sounds great but I do not want to use any additional power supply.
    I want to have just one USB cable from my PC to arduino,is that possible?

  4. #4
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    Re: Baclight pael with arduino

    30 Leds would draw 500 mA but you're USB would be the restriction.
    I Googled "usb max current" , and found that the
    USB by default will deliver 100mA of current!
    So I guess you would nead a Powered USB Hub.

    Life was hard, but then came Windows 7.
    Now we can fly! --------
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  5. #5
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    Re: Baclight pael with arduino

    that sounds ok for arduino mega
    orry for small image

    Untitled.png

  6. #6
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    Re: Baclight pael with arduino

    why do you want to connect your backlights to an Arduino, surely in a real cockpit they are fed from a switch? No worries about current draw. I use a 12 volt feed from an old PC power supply to feed all my backlights "hundreds of LEDS", but all are controlled via switches.
    geoff

  7. #7
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    Re: Baclight pael with arduino

    True
    I think I jst add one switch on mu panel