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Path: utzoo!linus!decvax!duke!unc!mcnc!unc-c!dya
From: dya@unc-c.UUCP
Newsgroups: net.micro
Subject: Re: How do you connect a monitor to a VIC-20?
Message-ID: <1105@unc-c.UUCP>
Date: Tue, 20-Sep-83 13:06:03 EDT
Article-I.D.: unc-c.1105
Posted: Tue Sep 20 13:06:03 1983
Date-Received: Wed, 21-Sep-83 01:28:24 EDT
Lines: 33

References: hocda.284


Or anywhere else, for that matter, it's easy to get at composite video.
Beware, however, that some CV's are more "conditioned" than others; for
example, you do need a buffer amplifier for the Ataris.

The Commodore VIC-20 uses the Aztec video RF modulator. I believe the
video input is pin # 3. Get a scope and start probing around for anything
that looks like composite video.

The sync tips must be most negative.  Be sure to decouple this with at
least 100 microfarads, and observe polarity (usually, and in the Aztec
case, the + mark goes to the computer side.  Coax cable must be used to
keep out nasties.

If you are feeling ambitious, put in an opamp buffer with some gain and
filtering (corner frequency of 4.5 mc/s). This will improve crossmodulation.

    Judging by what most colour computer manufacturers use to generate the
colours, this result may not be adequate.

ONE MORE THING: Be sure to unhook the video input to the modulator itself,
whatever it is.  Computer manufacturers generally avoid using any kind of
double balanced mixer in their equipment to inject the sound carrier. Consequently,
it is possible to get a gross 920 kc beat from the sound inject circuitry
(ATARI users, NOTE !!!)

Any specific questions, just send mail

                      { duke!mcnc!unc-c!urp!dya  }

-- David --