PET composite video adapter

Chuck Guzis cclist at
Mon Oct 13 11:46:01 CDT 2008

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.  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).

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.


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