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<DIV dir=ltr align=left><SPAN class=476363400-21092021>S<SPAN
class=476363400-21092021>o, I built the new circuit (I've attached the schematic
again here). Note that I changed the 100k resistor from the diode to
ground to 10k, as this made the simulation results ever so slightly cleaner at
the transitions.</SPAN></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021></SPAN></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021>Results: MC14024BCP and CD4024BCN are still clocking as
they should. CD4024BE is still clocking on the wrong
edge.</SPAN></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021></SPAN></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021>I swapped the diode and the 10k resistor just to see if
that would have any effect -- it didn't. Also, I like them the way they
are because the keep the levels closer to the opamp output and
zero.</SPAN></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021></SPAN></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021>I've also attached a scopeshot of the falling edge,
taken with the probe attached to the 4024 CLOCK pin. As you
can see, it is just about the cleanest transition you could ever hope to
see. If that edge can't clock a CMOS chip properly, then nothing
can.</SPAN></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021></SPAN></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021>So, I'm out of ideas. I could disconnect the 20k
resistor to see if the rectifier is affecting the CLOCK pin, but I honestly
cannot see how it could, given the very low output impedance of the TL072.
The comparator is more or less completely optimized now, and is performing
admirably.</SPAN></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021></SPAN></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=476363400-21092021><SPAN
class=476363400-21092021>I guess I'll try Tim's simple clocking circuit on
breadboard to see if I can get that to work. However, I'm not holding out
much hope, since I think it is fair to say that my comparator circuit is
generating what looks to be a more or less perfect clock
signal.</SPAN></SPAN></DIV></BODY></HTML>