TTL RGB ==> PC

Tony Duell ard at p850ug1.demon.co.uk
Wed Nov 7 18:28:51 CST 2007


> > For monochrome composite video, or separate RGB
> > (wheter TTL or analogue), 
> > then yes, all you should beed to do is tweak the
> > monitor. The horizontal 
> > frequencies are close enough that it will proabably
> > sync anyway, if not, 
> > then a touch on the horizontal frequncy control
> > (maybe an inductor) will 
> > do it. The vertical hold control will probably need
> > re-adjusting, but 
> > that's all.
> 
>  Curious where I'd put the inductor...

I was refering to the fact that the horizontal hold control might well be 
an inductor in some older monitors. You shouldn't need to add an inductor 
anywhere.

[...]

> 
>  These are presumably composite color PAL units
> (Australia). Have any idea what would go into a

If you feed that into an NTSC composite monitor and tweak the vertical 
frequency, you should get a good _monochrome_ pictore.

> PAL-NTSC converter (how many (roughly) and what type
> of components)? I'm just curious how complicated
> something like that would be to construct.

Normally you decode the PAL signal to RGB (or at least to the YUV 
signals) and re-encode as NTSC. If you do the first part, you might as well
display the RGB sigals directly, assuming you can find some way to get 
your monitor to accemt them.

The decoder is not that complciated if you use the ICs used in older TV 
sets (perhaps 3 or 4 chips, cryutal, maybe a delay line, lots of 
passives). Setting it up can in interesting the first tiem (I speak from 
expeirence). It's not something I'd recomnend tryign to build unless you 
have some expeirence with video circuitry.

-tony



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