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From: dbell@cup.portal.com (David J Bell)
Newsgroups: sci.electronics
Subject: Re: Sync'ing two pulse trains?
Message-ID: <40044@cup.portal.com>
Date: 12 Mar 91 04:51:53 GMT
References: <1991Mar9.015404.21727@leland.Stanford.EDU>
Distribution: usa
Organization: The Portal System (TM)
Lines: 30

Easy....   You'll need two inverters, unless your S1 and S2 are
available as negative-going pulses, and a single type-D flip/flop. 
(74LS74, or many equivalents is fine.)

           |\
S1 --------| >o---------------
           |/                |
                             o
                          -------
                          |  S  |
                    ------|D   Q|------------> S3
                    |     |     |
     |\       (Gnd) V     |     |
S2 --| >o-----------------|>C   |
     |/                   |     |
                          |_____|


How it works:

    S1 going to a HI level causes the SET input of the D flip/flop
to be activated, bringing Q HI.

    Falling edge of S2 causes a rising edge into the CLK input, which
causes the LO input to D to propagate to the Q...

    This presupposes that S1 is never wide enough to overlap the falling
edge of S2...

Dave       dbell@cup.portal.com