Some sequencer fustration and CD40xxB replacement question.

[John E Blacet]

Differences in "supposedly identical" ICs from different manufacturers,
especialy in the logic area are rare. I do remember one instance where
4538s from one particular manuf. did not function in a fairly standard
circuit. We had to tell the buyer "no RCA" or the like. I don't remember
the exact manuf.

As far as the 4017, what are you trying to clock it with? Unless you are
using another logic device for clocking, the clock input may need a
schmitt tigger IC. You can also rig a ST from any logic gate or two
inverters by adding a couple resistors. This is covered in "The CMOS
Cookbook" by Don Lancaster.

Another alternative is just a transistor switch on the input. I suspect
that even some faster op amps would drive CMOS (watch the negative
swing!), but you would have to check this out...
-- 

Regards.
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John Blacet
Blacet Research Music Electronics
http://www.blacet.com
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blacet at monitor.net
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