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From: krc@cs.purdue.EDU (Kenny Crudup)
Newsgroups: sci.electronics
Subject: Re: Direct video input
Message-ID: <3676@medusa.cs.purdue.edu>
Date: 29 Mar 88 16:12:36 GMT
References: <283@ritcv.UUCP>
Sender: news@cs.purdue.EDU
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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?

Yup. Works Ok, but forget composite 80 x 24 color. (Even as RGB, see below)
Either use a cold-chassis set, or *USE AN ISOLATION TRANSFORMER*. Forget any
thing with tubes in it. That wreck.audio tube purist bullshit doesn't carry
over to video. It *can* be done, but you'll have real *fun*.

> Wouldn't it have to go right after the I.F amplifier?

Better than that- do it after the 1st video amp, just before the video output.
It has to be before sync separation, unless you intend to pipe in sync yourself.
Remove *all* the traps, filters, 3.58/4.5 ceramics etc. Once I made an AC-
coupled $45 b&w tv set into a DC-coupled monitor with decent resolution.
Damn good. Just moved around a few parts and stuff. No real hassle. Get
a Sams for the set, of course.

> Is there any way to add RGB inputs?  Now THAT would be a handy thing to have.

Yes, but depending on your set, it rides on a voltage level used for setting
brightness/picture. This is usually the case for discrete (several transistors
as opposed to all-on-one-chip-like-Sanyo Tv's). The everything on a chip
sets are a little bit better for this.

> Thanks...Jim

No problem.
-- 
Kenny "_R_o_b_o_B_r_o_t_h_e_r" Crudup		krc@arthur.cs.purdue.edu
Purdue University CS Dept.		
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