[sdiy] 4069 / 4049 VCA

[media at mail1.nai.net]

>>The 4049 vca originated from Popular Electronics some time (ages) ago.
>>The connection uses only one transistor of each inverter pair...
>
>Tomg's cookbook Hex VCA connects Vdd and Vss to ground.

Is the recipe online??

>So it is attempting to use both transistors.  I don't know if it
>really makes that much difference given the transistor asymmetry.
>
>>All 4049 are UB... there is no buffered version.
>
>Ummm yes there is.  I have a National data sheet that says so.
>There may not have been a B version at the time of that article,
>but there certainly is now.

Wow!!  You guys really are talking about the CMOS chip.  When I saw "4049"
I thought that's what you meant until I got to the word "VCA".

Afaik, National has handed over their CD4000 series to Fairchild, who lists
the 4049 and 4069 with the suffix "UB".

In the Harris book I have, both have the suffix UB.  The 4049 is is an
inverting "hex buffer/converter", and the 4050 is non-inverting.  The
CD4069UB is simply described as a "hex inverter".

The latest Digikey catalog lists both a TI CD4069UBE and a CD4069UBM as
"NEW!".  I don't know if that means they're new to Texas Instruments or new
to Digikey, or what the difference is.  If I had to guess, I'd say the "M"
is for military spec.

>Perhaps the idea of an _all_ 4069 synth is not quite practical.
>I have strayed from that anyway in my building since I have used
>4007 and 4027 as well as standard opamps (the linear V-I converter).
>At this point, my project is a "Mostly CMOS" synth, with the idea
>that many of the 4xxx parts are still common and inexpensive.

d00D!!  You're building a CMOS synth??

Hmmmm....maybe that isn't as insane as it sounds.  You can get triangle and
square waves out of a 4046, a sub octave with a 4027 flip-flop, some sort
of "ring mod" from a 4051/52/53 multiplexer, and I guess there are a number
of ways making a VCO by making the control voltage the supply voltage, but
I have no idea how you can make an exponential converter, VCA, or VCF, or
make an ADSR that doesn't rely on RC networks for timing each stage.  That
certainly doesn't mean that it can't be done, it's just that I have no idea
how the insides of these chip work.  For all I know, they could contain
tiny colonies of superfast ants.

Anyway, if you have any ideas, I'd love to hear them as most 4xxx chips are
inexpensive, and I already have a bunch of them lying around from various
sequencer clock projects.  Well, that's if the ants haven't died.