[Coco] PICs and S-Video

[Chris Hawks]

---Reply to mail from John Kowalski about [Coco] PICs and S-Video

> At 08:07 AM 23/02/2006 -0600, Chris Hawks wrote:
>>    Yeah, that's how it started. But, the 555(6) output is high when the
>>trigger is low (and HSYNC from the Coco3 is a high pulse), so I'll have to
>>invert HSYNC (another chip!) before it's fed to the timer 1. I should
>>be able to de-couple the connection from timer 1 to timer 2 with an RC
>>network.
> 
> Using one 555 would most likely require an extra inverter, but with the two
> timers on the 556, the 2nd timer on the chip might be used as a way of
> inverting the signal.
> 
> HSYNC in    ________--____________________--____________________--______
> 
> timer 1     __________---------------_______---------------_______------
> 
> timer 2     _________________________--____________________--___________
> (HSYNC out)
> 
> 
> -Timer 1 would trigger when the HSYNC goes low and Timer 1's output would
> remain high for the duration of the delay period.
> 
> -Timer 2 would trigger when the output of Timer 1 goes low and the output
> would be the new delayed HSYNC signal.

    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    --------__--------------------__--------------------__---------------

---End reply

Christopher R. Hawks
HAWKSoft
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