PET composite video adapter
ethan.dicks at usap.gov
Mon Oct 13 14:26:08 CDT 2008
On Mon, Oct 13, 2008 at 08:21:11PM +0100, Phill Harvey-Smith wrote:
> Ethan Dicks wrote:
> >P.S. - I found another type of composite circuit using a CD4011 as an
> >inverter and a CD4066 to mix the signals,
> Sounds like the circuit I have here from "The PET Revealed".
That is very likely, though I probably found a copy of just the
diagram somewhere on the web. I have a copy of the book at home,
but I didn't bring it with me.
> > but for some reason I don't
> >have all the components labelled on my drawing - the cap on hsync in
> It's not labeled on the diagram in the book, nor does the text say what
> value it is.
That would explain why my schematic doesn't have it, then.
> > One interesting variation with that one is that the 'LS02
> >circuit has a 1.5K pulldown on hsync between the cap and the gate,
> >while the CD4011/CD4066 circuit has a 10K pot. How much adjustment on
> >hsync is likely to be needed between the PET and the first gate of the
> >composite circuit?
> The text in the book says "You may encounter problems with the
> horizontal hold, but these can usually be cured by adjusting R1", and
> goes on to speak of low quality monitors or converted TVs...
Ah. Thanks much for that. I have plenty of small PCB pots... easy to
fit on in.
Ethan Dicks, A-333-S Current South Pole Weather at 13-Oct-2008 at 19:20 Z
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Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
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