Composite to S-Video

Started by blackevilweredragon, May 18, 2006, 01:42:17 PM

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blackevilweredragon

I made a circuit today that does the reverse of this, S-Video to Composite, as I wanted to use an S-Video only device on a Composite only monitor.

However, I thought, maybe I can connect something that is composite only, like an NES, or a Genesis II, and hook it up to my TVs S-Video ports, as the composite port broke off (this is my nice 20" TV)...

Here's the schematic for my S-Video to Composite adapter.  a similar circuit is floating around the net, but doesn't work as good (i found that having 3 caps instead of 1 makes the picture more stable)..

http://macteens.com/gallery/albums/userpic...o-composite.PNG

and here is the final product:  http://macteens.com/gallery/albums/userpics/TVcircuit.jpg

so, i tried using this circuit in reverse, have it take a composite source, and convert to S-Video, but this was the result..  as you can see, it's bad, and ugly...

http://blackevilweredragon.spymac.com/segastripe.jpg

however, using a composite source like my cable box, it doesn't look "as bad", but the cable box does yield dots moving on the screen all over the place..

http://blackevilweredragon.spymac.com/cablestripe.jpg

Is there anything I can add to my circuit to add the ability to cleanly do the reverse of what I designed it to do?  I would love to have an adapter that can go both ways...  Thanks!

(oh yea, this was my first soldering job btw, and i know it came out like crap, but my circuit works great for what i originally designed it to do..)

blackevilweredragon

hmm, this here is weird..  the shades of grey on eggman ship appear perfectly fine, but the yellow parts on his ship are showing the black vertical stripes...

what gives?

http://blackevilweredragon.spymac.com/eggman.jpg

blackevilweredragon

please?  3 days pass and no help?

Segasonicfan

hrmm, your post is a little confusing to me.  From my understanding, composite can be made from S-video very easily by simply combining Y and C.  I've never heard of using caps to do this, but I guess it should have the same effect.

Now, making S-video out of composite I'm not too familiar with.  I would imagine the quality to be somewhat lame in every case just because your decoding a single video signal.  If I were you I would do either one of two things:

1) open up your tv and wire in a composite jack from where yours broke off (this should be very easy).

2) open up whatever system you are using and tap the RGB lines to make a REAL S-video converter using the CXA1645/AD725 encoder chips.  I have info/schematics/pics on my site on how to build these.  That way you will get true high quality S-video.

-Segasonicfan  
MY WEBSITE: https://segasonicfan.wixsite.com/retro
I design PCBs for retro game systems :)

blackevilweredragon

Quotehrmm, your post is a little confusing to me.  From my understanding, composite can be made from S-video very easily by simply combining Y and C.  I've never heard of using caps to do this, but I guess it should have the same effect.

Now, making S-video out of composite I'm not too familiar with.  I would imagine the quality to be somewhat lame in every case just because your decoding a single video signal.  If I were you I would do either one of two things:

1) open up your tv and wire in a composite jack from where yours broke off (this should be very easy).

2) open up whatever system you are using and tap the RGB lines to make a REAL S-video converter using the CXA1645/AD725 encoder chips.  I have info/schematics/pics on my site on how to build these.  That way you will get true high quality S-video.

-Segasonicfan
well, the converting svideo to composite does need the caps, otherwise the picture looks very horrible, a lot of ghosting, and the dot crawl is so massive, it's not funny...

sadly, i don't want to go into the TV, and i don't want to mod my Genesis in any way (at the moment atleast)