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From: tran@elaine14.Stanford.EDU (Hy Tran)
Newsgroups: sci.electronics
Subject: Sync'ing two pulse trains?
Message-ID: <1991Mar9.015404.21727@leland.Stanford.EDU>
Date: 9 Mar 91 01:54:04 GMT
Sender: news@leland.Stanford.EDU (Mr News)
Distribution: usa
Organization: Stanford University - AIR
Lines: 30



I have two signals:  Call them S1 and S2.  S1 is at frequency F1; S2
is at frequency n*F1 (say, 7*F1).  The frequencies are locked, but not
in phase.
       _                                         _
______| |_______________________________________| |_________   S1
   _      _      _      _      _      _      _      _
__| |____| |____| |____| |____| |____| |____| |____| |____     S2

What I want to do is to stretch out the pulse of S1, so that its
falling edge is synchronized with the next S2 falling edge:  (i.e.
obtaining an S3 like this)
       _                                         _
______| |_______________________________________| |_________   S1
   _      _      _      _      _      _      _      _
__| |____| |____| |____| |____| |____| |____| |____| |____     S2
       ____                                      ____
______|    |____________________________________|    |_______  S3

I think that can be done with a flip-flop, or some sort of logic
gate(s), but I'm more an analog type of person.  Suggestions, please?

Thanks,

Hy
tran@sun-valley.stanford.edu

P.S. Oh, if it helps: The frequencies I'm looking at are on the order
of 0.5 to 20 kHz.