[sdiy] 4069 / 4049 VCA

[Scott Gravenhorst]

I have a copy of a schematic from TomG's cookbook portraying
a hex VCA made from a 4049.  Unfortunately, it is labeled simply
'4049'.  I am assuming that it is the UB part because it runs in
linear mode.  

I learned (right here!) that the 4049UB does not employ symmetrical
transistors as the 4069UB does.

Because of the asymmetry, I assume I would have to adjust some
resistor values (and also the pinout) so that I can use the 4069UB.

A couple of questions:

1) Does the asymmetry of the 4049ub actually provide a benefit?
   (I do realise the original intent was that the 4049 would
   do CMOS to TTL/DTL conversion).  My question refers to a
   benefit that might be realised in the VCA application.

.. if not, 

2) Has anyone already designed a 4069UB based VCA (so I don't
   need to figure out why a wheel has to be round again) ?

=========================================================  
- Government: The other religion.
- The media's credibility should always be questioned.
- Lambs who lie down with lions are lunch.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.GTE.NET/res0658s/TekLab_FatMan_WebSite/index.html