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VGA to NTSC/PAL converter

Discussion in 'Electronic Design' started by [email protected], Sep 14, 2005.

  1. Guest

    hi,
    I am designing a VGA to NTSC/PAL converter card for my home computer.
    For the conversion part i used the VGA chip AD724.I wire the circuit in
    the datasheet itself. i used the srystal for NTSC output. But i didn't
    get any picture on TV screen. There was only a white screen with one
    small black line on the middle of the screen. Anybody have experiance
    with this AD724 chip. Pls help me to get the correct output on TV
    screen.
     
  2. Pooh Bear

    Pooh Bear Guest

    For starters, TV frame rates are rarely compatible with their computer
    counterparts. That's big problem #1 !

    That's a guess as to your problem since you don't provide enough
    information to deduce any more.

    Graham
     
  3. You realize that the AD724 is simply an encoder, right? It makes a
    composite signal from RGB but the line/frame rates must be NTSC.
    Wouldn't it be easier to simply buy an ATI (or others) video card with
    composite out? I bought one last year at Fry's for $50.
    GG
     
  4. Jeroni Paul

    Jeroni Paul Guest

    expuso:
    You must set your PC card to output the correct frame rate. Look for drivers
    that will do this or try the PowerStrip program, that depending on your card
    model will let you set up any frame rate. You'll have to play with all the
    timing settings or look at groups.google.com for NTSC values that other
    people has worked out.
     
  5. raseelmusl wrote ...

    http://www.tkk.fi/Misc/Electronics/circuits/vga2tv/vga2palntsc.html

    Seems pretty unlikely that you can do a project like this
    without an oscolloscope to view your waveforms.
     
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