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

[patchell]

    Another good canidate part is the CD4007.  RCA used to have another
similar part, I think it was the CA3600.  The part has 6 mosfets in it.
Two are committed as a CMOS inverter.  The other four have their drains
uncommitted (the sources are tied to the power supply rails), I can't
remember what they did with the gates...oh yes, the gates of each pair are
connected together...but, this part might offer a little more flexability
in certain designs...if you can still get them of course.

Magnus Danielson wrote:

>
> Hmm interesting!
>
> This kind of rings a bell in me, I've actually considered the oddball
> idea of building a synthesizer with 4069s as the only active
> component.
>
> A 4069 is basically a high gain inverting amplifier. If you look at
> the above VCO, you should be able to remove the TL072 by using two
> more of the 4069s inverters. Just think of it, it is indeed possible
> even if it requires some more thougth.
>
> As for my idea, naturally the exp-transistors can't be avoided.
>
> As for the filter, there is the JHs WASP clone, but I do wonder if not
> the CA3080s could be replaced by 4069s if given thought.
>
> VCAs is not problem, a 4069 and 12 1MOhm resistors and there is 6 VCAs
> all prewired together to form a mix. Then for the virtual ground
> summer completion a single 4069 inverter for the buffering.
>
> For signal and CV summers will single 4069 gates do just fine.
>
> I think it should be possible to do an envelope generator too.
>
> I don't think it will be a high precission synth, but I am quite sure
> that one could make one that actually works. I'd like to dub this
> synth to 4069.
>
> There is surely a few problems in doing this, but I think those
> problems are there to be found and lessons to be learnt.
>
> It is strange what a brain can produce after just getting out of a
> hang-over ;O)
>
> Actually, I think I'll start scetch some on this right away... ;O)
> Any takers?
>
> Cheers,
> Magnus

--
 -Jim
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