[sdiy] 4046 differences?

[Harry Bissell Jr]

My experience with different manufacturers
of CMOS A and B series chips (not specifically 4046)
shows that often there are differences in gate
capacitance that can cause false triggering on edges.

Sometimes adding a small cap (10-20pf) to some inputs
will fix these mfg. specific differences.

WATCH out for schmitt trigger inputs... some
manufacturers handle them differently.  I remember
getting burned by one manufacturer who AND-ed two
signals and used a single schmitt trigger stage
following (duh!) instead of using TWO schmitt triggers
followed by the AND.  Same logic truth table,
completely different analog performance

H^) harry



--- Scott Gravenhorst <music.maker at gte.net> wrote:
> Kevin Lightner <synthfool at synthfool.com> wrote:
> >Just curious if anyone knows what the differences
> are between some 4046 PLL's?
> >For example, only Motorolas work well in Polymoogs,
> I've found.
> >Never tried any 74HC types, but several other makes
> of CD4046's, just 
> >don't operate correctly in these circuit.
> 
> 4046 has a max VCO frequency of 1.3 MHz
> 
> 74HC4046 has a max VCO (center) frequency of 17 MHz.
> 
> 4046 has a Vdd - Vss range of 3 to 18 volts, 
> 74HC4046 is 3.0V to 6.0V
> 
> 4046 has 2 phase comparators
> 74HC4046 has 3 phase comparators 
> so watch pinouts if you are trying to crossbreed a
> circuit.
> 
> I can't speak to differences between mfrs of 4046
> (not HC), and I've never done
> instrument repair other than repairing my first
> FatMan after frying it and a
> FatMan (stock) doesn't have a PLL.  I think I still
> have the same tube of 4046
> that I started anyway.  They work as the datasheet
> describes...
> 
> 
> 
> 
> 
>
---------------------------------------------------------
> - Where merit is not rewarded, excellence fades.
> - Hydrogen is pointless without solar.
> - What good are laws that only lawyers understand?
> - The media's credibility should always be
> questioned.
> - The only good terrorist is a dead terrorist.
> - Governments do nothing well, save collect taxes.
> 
> -- Scott Gravenhorst | LegoManiac / Lego Trains /
> RIS 1.5
> -- Linux Rex         | RedWebMail by RedStarWare
> -- FatMan: home1.gte.net/res0658s/fatman/
> -- NonFatMan: home1.gte.net/res0658s/electronics/
> -- Autodidactic Master of Arcane and Hidden
> Knowledge.
> 
>