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Apple II Colour Demodulator

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Uploaded by on Jan 28, 2012

I'm working on a circuit that can demodulate the NTSC output of an Apple //c to a YUV component signal. This is the basic concept of the circuit working, which currently only decodes the red difference signal, which is why the colour is lacking. I have run out of resistors needed to wire up the blue difference signal. I'm using MC1496 mod/demodulators.

I'm in a PAL region (Australia) and have a PAL //c without the composite module. This circuit should work unmodified with NTSC machines too.

More coming.

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Uploader Comments (256byteram)

  • This gives me an idea, but I'd probably better not share it with you because you might not be able to resist making it :p

    Also, this is still 60Hz? I'm presuming this TV doesn't quite like 60hz (I've had tv's that can 'do' 60Hz but the image wasn't ideal in one way or another) or was the original game not fullscreen (also no familiarity with apple][ hardware/software)

    BTW, ever find a simple YUV-2-RGB solution?

  • @bobamu The signal is 50Hz. The timings were modified for the PAL model Apple II's. I have found a YUV to RGB converter circuit which is three op-amps and about a dozen or so resistors. YMMV on 'simple' though :)

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  • @256byteram Ah, that explains why it's not a fullscreen image? That YUV 2 RGB circuit might be useful for a few things. and if it's simple enough for me to wire up then it's simple enough :D

  • @256byteram Ah sorry, Itend to forget that theses incompatibilities leads to monochrome pictures.

    I also believed you were American all the way long, sorry.

  • @LunaVorax I don't have a PAL modulator for my IIc, which means I can't have colour. This circuit will let me.

  • @Saavik256 I meant, what advantages will it have.

  • @LunaVorax My guess would be so that one can take a NTSC source and display it on a monitor with YUV component input. ;)

  • I'm not familiar with the Apple //, what is the purpose of this?

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