building my own s-video ---> composite converter

[geauxlsu]

Making your own s-video to composite video converter

Does anyone think this would work?

http://www.epanorama.net/circuits/svideo2cvideo.html

What I'm wanting to do is connect my PC and my TV using this technique. It's not that I'm too cheap to buy a converter. Well.... yeah I am, but I would like to see if this circut would work. Plus, I can use some of the crap I'm learning in my circuts class.

The only problem is that I can't tell by the picture where the 470 pF capacitor is connected. Also, what if I want to send the audio in or out, how would that change this circut? Ideas and suggestions welcomed.

Thanks!

[edDV]

No audio on composite or S-Video. Use audio card out to TV RCA red/white connections for audio.

Capacitor goes in the chrominance path per the schematic.

[geauxlsu]

Oh, oops that was kind of obvious, RTFM . Any ideas on how to make it better, or alter the signal?

[edDV]

Alter the signal in what way?

You are just summing luminance and chrominance to make composite.

[geauxlsu]

I had seen a schematic of a circut more complex to this one, but simialr in what it accomplishes (via a link on the page) here
http://archive.espec.ws/server2d/books/Magazines/Elektor/Elektor2001/Articles/E/e019032.pdf
I guess what I'm trying to get at is this (quote from original article)

"This circuit works in practice quite well even though the circuit operation is not ideal. This means that impedances and signal levels not matched exactly right, but near enough to work accetably. The picture quality you get from this circuit is is good, but not as good as with best possible composite video output circuitry."

The author talks about impedances and signal levels not matching and that gives less than optimal results.
I was wondering how to improve on this simple circut's shortcomings by maybe knowing or finding the impedances and signal levels. I'm not anywhere near an Electrial Engineer (actually I'm ChE), so explaining this is a little difficult for me.

Thanks man

[edDV]

That link is for going the other way: composite to S-Video. The circuit they show is a simple notch filter and is a low end solution. It is also intended for PAL. NTSC would have notch and high pass filters at 3.58 MHz.

If you want to go composite to Y/C, this is the best link to study.
http://members.aol.com/ajaynejr/vidcomb.htm

You said you wanted to go from a computer graphics card S-Video output to a composite TV input. Better would be S-Video to S-Video but if the TV only has composite inputs, a simple sum circuit is all that is needed.

[geauxlsu]

Great. The TV I'm wanting to connect to is an old Emerson model no: P.O.S. 3000, which only has composite Tv inputs.
Do you (anyone) know of any other good articles I may referr to?

[edDV]

Great. The TV I'm wanting to connect to is an old Emerson model no: P.O.S. 3000, which only has composite Tv inputs.
Do you (anyone) know of any other good articles I may referr to?

What do you want to know? The link above is the best I've found.

Most graphics cards include a S-Video to composite adapter or cable.
http://www.svideo.com/prosvideo6.html

[geauxlsu]

I just got done reading the article that you linked me to and I must say that it is very informative. So, like the article said, comb filters are useful only for going from a composite source to a single source. So, not sutiable for computer to TV, but from TV to computer (if not using TV's S-video output). Yet it seems like an expensive solution.

Oh crap, I didn't mean composite TV inputs.... I meant coaxial (cable) inputs. I screwed up the terminology. No AV inputs. Well, that changes the whole post. So, now I'm changing directions here because I'm a dumbass and can't read. I was reading composite, composite, composite. But at the same time thinking coax, coax, coax. It's too late for me today.

New senario:
try s-video to coaxial. Could a home made circut take s-video out and convert it to cable input?

[edDV]

Get this
http://www.walmart.com/catalog/product.do?product_id=2181628

or build this
http://www.apogeekits.com/tv_transmitter.htm

[geauxlsu]

How funny and ironic how I manage to waste my time and other peoples for a Wal-Mart item. I appreciate your efforts.

Say, ed, what kind of linux box do you have? I dual booted my laptop with xp and mandrake 10.1, but drake gave me a helluva lot of problems w/ my wireless NIC so I erased the partition.

[edDV]

How funny and ironic how I manage to waste my time and other peoples for a Wal-Mart item. I appreciate your efforts.

Say, ed, what kind of linux box do you have? I dual booted my laptop with xp and mandrake 10.1, but drake gave me a helluva lot of problems w/ my wireless NIC so I erased the partition.

SUSE on one, Red Hat on another.