T3D A good chip for multiplexing video.

[Robert Cruickshank <robcruic@xxxxxxxxxxxx>]

Here's a suggestion, if you are considering building a multiplexer for
field-sequential video: get a hold of the Comliner CLC411 video op-amp.
The cool thing about it is that it has a disable pin, which puts the
output into a tri-state mode. It is *very* simple to switch between the
left and right video, using a sync separator driven by one of the inputs
to control the disable pins. The outputs of the amps are then simply bused
together. The other nice thing is that the chips can drive a 75ohm load
directly. I was able to build a working multiplexer with an absurdly low
parts count.(Just got it working today) I still have a bit of fiddling to
do with it, but I'm pretty
happy. Unfortunately, I have come down with the flu yet again, and I had
to leave work before I could  hook up a couple of cameras to it, but the
test signals looked nice!                  

Since I've written the above, I've recovered from the flu, but I still
haven't done anything with the circuit.  I just picked up the latest issue
of Circuit Cellar Ink, and, lo and behold, there's a project to build a
video multiplexer! Apparently, theirs is used to do frame grabs of stereo
pairs for machine vision. It's a lot more complicated than mine, but worth
a look. 


Rob Cruickshank      Toronto, Canada 
www.interlog.com/~robcruic
                



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End of TECH-3D Digest 471
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