[sdiy] CMOS CD4046 ring mod??

[Scott Gravenhorst]

harry <harrybissell at prodigy.net> wrote:
>Hmmm... as I recall former synth-diy "bad boy" Bjorn Julin used the 4046
>phase comparator I  (ex-or gate) as a ring modulator in his 4046 VCO that
>also featured a sawtooth output. Using the ex-or gate as a ring mod might
>not
>have been the most clever feature of the design (the sawtooth out is,
>IMHO)...
>but making the unused phase comparator a ring mod is pretty cool.

Yep, this is the one that I mentioned...  I could never
get any serious range out of the VCO part, so I never
finished making a VCO out of it.  If anybody can claim
better than 2.5 octaves of linear range, I'd love to
see how they did it.  It would be a nicely featured
VCO with saw, square, ringmod and PWM all from two IC packages.
If I could get 6 octaves, I'd be happy with it.

I'm thinking of trying an external linear V-I current sink 
out of pin 12 to try to linearize it over a wider CV range, 
but no round-tuit yet.  His technique for making saw would 
still be useful for using the device as a PLL though.

>H^) harry
>
>Tony Allgood wrote:
>
>> >So has anyone ever built a ring mod using a 4046??
>>
>> The Radio Shack MG-1 used the 4046 VCO as a high frequency oscillator
>> for a top-octave doo dah for its polyphonic output. And the little ex-or
>> in the 4046 was used to create the 'bell-tone' from the two real VCOs
>> also contained within the instrument.
>>
>> Regards,
>>
>> Tony Allgood, Penrith, Cumbria, England
>>
>> Oakley Modular Synth and TB3030:
>> www.oakleysound.com/projects.htm
>> My music: www.mp3.com/taklamakan
>
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