03-11-2005, 20:26
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חבר מתאריך: 29.06.05
הודעות: 1,645
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מצאתי מדריך לזה ... (האם זה זה?):
4.10) VGA to grayscale composite monitor
This will only work if you can program the video card to produce a compatible
resolution and scan rate.
If you would like to experiment, here is a really simple circuit that may work
well enough for combining Hsync, Vsync, and one of the VGA color signals, say
green, into a composite video.
If the monitor sense lines on the VGA connector are tied MS1 (pin 12) = GND,
MS0 (pin 11) = no connect, then some programs will default to monochrome and
use a reasonable color map. I don't know how you will get a reasonable
mapping to monochrome for the others.
All you will need are 4 resistors.
I am calling your connector on the monitor 'Composite Video In'.
* Hsync through 500-1K ohm (R1) to Composite Video In.
* Vsync through 500-1K ohm (R2) to Composite Video In.
* Green Video through 200 ohm (R3 - variable) to Composite Video In.
* Green Video side of R3 to Ground through an 82 ohm (R4) resistor.
* Tie this ground to the BNC or RCA connector ground.
R1
Hsync o--------/\/\/------------+
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R2 |
Vsync o--------/\/\/------------+
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R3 |
Green Video o----+---/\/\/--+---------+--------o Composite Video In
| ^ | (Termination = Hi Z)
\ +----+
/ +--------o GND of monitor
\ R4 |
/ |
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GND (shield) o----+--------------------+
It is essential that all this be built as close to the monitor as possible
for best signal quality.
Set monitor video termination for Hi-Z. R4 provides the cable termination
to minimize reflections and ghosting of the green video signal.
Set your video card for negative sync polarity.
You may need to tweak these values for best results. This will depend on
your actual signals. The variable R3 may provide enough range for this.
* מתוך http://www.repairfaq.org/REPAIR/F_v...tml#VIDCONV_018
נערך לאחרונה ע"י MCGP בתאריך 03-11-2005 בשעה 20:28.
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