[Coco] PICs and S-Video

[John Kowalski]

Christopher R. Hawks wrote:
>    Thats' what I thought 'til I found out that the output will ALLWAYS be
>high when the input is low. So the output of timer 1 is not what you show,
>but:
>
>timer 1
--------__--------------------__--------------------__---------------

I added a quick-and-dirty HSYNC delay to my SVideo circuit using the 556
timer and it seems to work okay.  (It's quick-and-dirty because right now
it's just a 556 and a bunch of resistors and capacitors hanging off wires
coming off the SVideo board.)

It was a bit fiddly to figure out all the values for the resistors and
capacitors - I had to use an oscilloscope to get all the timing and trigger
input levels right.  The two trigger inputs in particular need to be R/C
filtered just right so that the 556 will only trigger on the lowest 'spike'
and not the full duration of lows.

I figure I'll move the (mess of wires) circuit onto the RGB-to-SVideo board
itself over the weekend and jot down a diagram of the wiring and components
and email it to you.  (Parts are one LM556CN, 5 capacitors and 6 resistors -
plus optional trimmers if you want to be able to adjust the delay time
and/or pulse width.)

                                         John Kowalski (Sock Master)
                                         http://www.axess.com/twilight/sock/