>>
Hi there. I'm playing around with video and PICs, and I'd like to
overlay signals on the video.
Question is: How do I detect the VSYNC and if possible HSYNC signals?

**** I don't want to use ICs like LM1881 or EL4581, because I can't get
them at my local electronics store, and I have to order them from
somewhere else (and wait!). ****

Is there a way of doing that with op-amps or something? All I want is a
pulse on the PIC port when VSYNC is present, so I can trigger the
software.
<<

This is like asking is it possible to heat food without a microwave oven.
Early TVs are an existance proof that this can be done with analog
electronics without any integrated circuits.

You first have to detect Hsync.  This is easy as it is the deliberately the
most negative point of the waveform.  Next low pass filter the Hsync pulses
and compare to a threshold.  That will be Vsync.  The Hsync pulses are
stretched during the vertical blanking interval.  If you don't want the lag
from a low pass filter, just look at the length of Vsync pulses.  Hsync
starts at the first long Vsync pulse.


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