Re: [stella] Re: A/V mods

Subject: Re: [stella] Re: A/V mods
From: Chris Wilkson <ecwilkso@xxxxxxx>
Date: Mon, 1 Mar 2004 06:06:47 -0500 (EST)
Gah...I had written a longer message, but my email connection failed.
No way of salvaging.  Grr.  Sometimes I hate MIT....

I checked the ML6415 when you first posted about it.  It's a nice part.
It has an RF-ready output, a separate luma and chroma and an internal
adder to produce composite.  Everything is nice.  It was $4-5 though.

We already have a complete RF section, including the modulator.  (But
we really don't that that anyway.)  You still have to build the analog
video signals using discrete components.  In the absence of a high speed
d2a, (and sampling, etc) you don't get aliasing so the filters aren't
really needed. And since you're building them from scratch, you can just
make the signals clean to start with.  The only novel feature really is
the internal composite generator.  But if you're settling for composite
you probably aren't worried about match impedances or absolute video
levels anyway.

The ML6415 would be great in digital TV realms, but I think it's overkill
here.  It would be nice to have a single, do it all part in our world.
Believe me...I'd like that more than anyone here.  I wish it could work.
But with our hand-built, low frequency analog signals, I think it's just
another part to add cost.

-Chris

On Sun, 29 Feb 2004, Eric Ball wrote:

> A while back I stumbled across the Fairchild Semiconductor ML6415. This (and
> it's cousins) is a simple video filter which appears to be exactly what the
> doctor ordered. This single chip takes in luma and chroma, and outputs luma,
> chroma & composite signals ready for a 75ohm cable. (I haven't found an
> equivalent IC for the audio side yet, but a standard op-amp or a Maxim
> MAX44100 headphone amp might work.)
>
> It might also be necessary to adjust the TIA chroma output with a resistor
> ladder to give it the swing the ML6415 wants. But this looks like it has the
> potential to give the best A/V output.
>
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