[sdiy] Multivibrator IC questions...

[James R. Coplin]

I'm looking into making a circuit that takes a trigger or gate as input and
outputs a modified pulse length.  I was looking at some multivibrator ICs
like:
 
http://www.fairchildsemi.com/ds/74/74VHC123A.pdf
 
My problem is that I often seem to be stuck with pulses, triggers, clocks
etc. that I need to transform into shorter or longer bits for control of
envelopes, sequencers, etc.  The multivibrator seemed the easiest approach
to have a user assignable gate length based on a triggered input.  The pulse
time in seconds is PW=Rx*Cx where Rx is ohms and Cx is farads.  There is no
limit on Cx but Rx is limited to 1k.  So I thought by using a 1k push-pull
pot, you could select two different caps and have a short and long time
control. 
 
So, there are a kazillion of these chips out there.  Is there really any
difference or would the above one work out fine?  They come two to a chip so
for a couple of ICs I would get 4 independent processing thingees.  Are
there other approaches I should be considering, pitfalls etc.? Thanks!
 
James R. Coplin
***************
If anyone asks of my whereabouts,
simply tell them i've gone out the window
for a spot of tea and am not
expected back any time soon.
***************
 
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