32 lines
1.6 KiB
Markdown
32 lines
1.6 KiB
Markdown
RGB to Component/S-Video/Composite Converter
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This is a further development of the RGB-to-component converter I built
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about three years ago:
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https://upverter.com/salfter/365dcb155a88fcf1/rgb2component/
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This version replaces the two MAX4451 dual op-amps with one MAX4383 quad
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op-amp; specs for the two are similar, so performace should likewise be
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similar. The rather large can-type electrolytic capacitors are also
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replaced with smaller tantalum capacitors.
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More significantly, the new design includes a Sony CXA2075 video encoder so
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it can produce S-video and composite output as well. I've found support for
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240p component video in newer displays to be somewhat iffy; perhaps 240p
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over S-video will be more widely usable. There should be no to minimal
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degradation of sharpness with S-video vs. component video. Composite video
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will be the usual hot mess, but since the chip supports it, we might as well
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implement it.
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This board is intended to plug into the RGB output jack of an Apple IIGS.
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If you want to use it with something else, you can either rework the DB-15
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connector end to something more suitable for your application or you can
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build a cable that adapts your application to the IIGS pinout: red on pin 2,
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green on pin 5, blue on pin 9, composite sync on pin 3, +12V on pin 8, -5V
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on pin 7, and ground on pins 1, 6, and 13.
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The board layout supports both NTSC and PAL, and is configured for NTSC by
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default. Configuring it for PAL requires cutting the NTSC jumper (marked as
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such), bridging the PAL jumper, and replacing the crystal and one resistor
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with parts with different values as described in the schematic. |