PET composite video adapter

[Ethan Dicks]

On Mon, Oct 13, 2008 at 09:46:01AM -0700, Chuck Guzis wrote:
> On 13 Oct 2008 at 4:08, Ethan Dicks wrote:
> 
> > The schematic shows the horizontal sync coupled to a gate via a "2200 mf"
> > non-polarized cap.  I don't know that I have any disc or ceramic caps that
> > large lying around.  The output of that gate (which NORs the inverted
> > vertical sync with the massaged horizontal sync) feeds unto a "47mf"
> > tantalum cap (then pulled down to ground by a diode, and wire-ored to
> > inverted video out/composite out via a 470 Ohm resistor).  I have 47uF caps,
> > but that seems pretty large to me.
> 
> That 2200mf is off by at least 3 orders of magnitude.  0.22 uF  is 
> probably more like it. 

I can entirely believe that.  What I'm wondering is if the original
article should have read 2200pF.

> The 47 uF might be okay, but I suspect that 
> 4.7 uF may also work just fine.  (But I don't have your circuit, so 
> it's really difficult to say for certain).

Agreed.
 
> It's been a long time since I wired up one of these, but ISTR that I 
> didn't find component values to be very critical.

Glad to hear it.  I'm going to build the first version on a proto board
so it will be easy to swap out caps.

-ethan

-- 
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Ethan.Dicks at usap.gov            http://penguincentral.com/penguincentral.html