From: firstname.lastname@example.org (Jeff Artz)
Subject: Re: Automatic Video Switch
Date: 16 Jan 2003 20:53:15 -0800
NNTP-Posting-Date: 17 Jan 2003 04:53:16 GMT
email@example.com (u1061771156) wrote in message news:...
> In article <firstname.lastname@example.org>, Jeff Artz wrote:
> ... details snipped
> > Anyways, I was thinking that once I have both the DVD CV and the
> >Receiver's Output CV, I could just use an analog comparitor and some
> >filtering circuity (to prevent any 'false triggers') and buffer that
> >signal to turn on the relay. That should work, right? Any
> >suggestions for specific components?
> > Thanks for reading my post!
> The LM1881 sync separator chip is useful for tasks like this.
> Given a composite video signal, it will tell you whether you have
> valid sync or not, in a way that is immune to DC drift and picture
> content. Read its datasheet on the National website.
> Here in Europe, incidentally, most AV equipment has "SCART" connectors
> which contain a pin to control input switching.
Thanks for your suggestion, but the issue is that I want to pass the
VCR and Sattelite Composite video to the Projector when they're used,
but when the DVD is selected, I'd like to switch to the RGB inputs. I
plan on doing that by 'listening' to the DVD's composite video, and to
the selected output of the Receiver. This way, when the VCR or
Sattelite are selected, the projector will use the Composite video,
and when it's on the DVD player, it will switch to the RGB input from
I figured a 'simple' comparitor circuit would work... If the
'Input' and 'Output' signals are exactly the same (Input = DVD's
composite Video, Output = Receiver's selected video), then the DVD is
selected on the receiver, and a relay should be energized to select
the RGB input on the projector.
I don't think that I need to split out the sync, I would think that
I can just do a simple comparison between the two video signals.