Doing it all in 4069s (Was: Re: [sdiy] New Vco (new images))

[Scott Gravenhorst]

AFAIK, to use a 4069 as a VCA element, you would need
to use it as a bank of 6 voltage controlled resistors.
(all of the VC resistors have a common connection).
Magnus just posted a 4069 ADSR that uses this approach.
Doing this requires not powering the chip at all, and
connecting Vss and Vdd together.  This connection is
the VC resistor array common.  The actual inverter outputs
are the other ends of the 6 VC resistors.  This dedication
means you couldn't do it with what you have left over.


>>     This fascinting topic has come up right as I am brainstorming about how
>> to use the 4069 as a VCA for the volume side of my
>> 4069-plus-a-few-caps-and-resistors theremin. I am using two 4069s, one for
>> the reference oscillator, and one for the variable oscillator, and have two
>> sections of the reference 4069 free. Is there anything I can use these
>> unused sections for? If I could use them as a VCA to control the volume of
>> the mixer circuit I could keep my parts count down and I won't feel so
>> guilty for tying those pins down to ground, but I know precious little about
>> VCAs, grrr. Any help is tremendously appreciated!

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