Path: utzoo!mnetor!uunet!husc6!think!bloom-beacon!gatech!udel!rochester!cornell!uw-beaver!uw-june!uw-entropy!dataio!pilchuck!ssc!markz
From: markz@ssc.UUCP (Mark Zenier)
Newsgroups: sci.electronics
Subject: Re: Direct video input
Message-ID: <1126@ssc.UUCP>
Date: 30 Mar 88 20:24:16 GMT
References: <283@ritcv.UUCP>
Distribution: na
Organization: SSC, Inc., Seattle, WA
Lines: 30
Summary: Watch out

In article <283@ritcv.UUCP>, jdc3538@ritcv.UUCP (Jim Cronin) writes:
> I would like to recycle some unused TV's for computer use.  Have any of you
> ever attempted adding a direct video input?  Wouldn't it have to go right
> after the I.F amplifier?  Is there any way to add RGB inputs?  Now THAT would
> be a handy thing to have.
> Thanks...Jim

A problem is that TV's are cheaply built and may not have any isolation 
from the power line.  Plug your TV in backwards and your computer blows up.

(This happened to some poor soul up here in Seattle about 10 years ago, and
the local club got together and scrounged up all the chips necessary to 
rebuild his altair)

Some older sets run with a rectifier right on the power line which feeds
everything.  These are bad news.  Newer sets use the Horiz. drive as a
switching power supply so most of the circuitry is isolated.

Check out the TV typewriter Cookbook by Don Lancaster for B&W mods. From
Sams about 1976 but it may still be in print.

You will probably be dissapointed in the resolution of the display since 
when selling a TV, It only has to look better than the one next to it
in the display room, and cost is everything.
Anything new enough to have decent resolution probaly has a direct input 
already.

As to RGB, it will be easier to add this than composite to some sets.

Mark Zenier