[sdiy] Expo in one chip?

[Jacob Watters]

Thanks David. Like this example posted on muffwiggler?

https://www.muffwiggler.com/forum/userpix/2077_dixie_cv_network_2.png

That sovles the resistor contact issue, but it still has a high part count.
Is there no such thing as a chip with linear in on one pin and expo out on
another?

On Dec 26, 2017 4:07 PM, "David G Dixon" <dixon at mail.ubc.ca> wrote:

> Yes, it's called the V2164, and it is available from Coolaudio in bulk, or
> from many retailers (Small Bear, Mammoth, etc).  It is a quad
> exponential VCA chip.  One VCA is used to temperature compensate the expo,
> and another is used as the actual exponential converter.  It requires an
> external summing opamp.  A third VCA can be used as a precision
> high-frequency compensation current source, leaving the fourth VCA for
> another use.  This is how all Intellijel VCOs (which I designed) are
> controlled, and they have a reputation in euro-land for very decent
> tracking and stability.
>
> ------------------------------
> *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org] *On Behalf Of *Jacob
> Watters
> *Sent:* Tuesday, December 26, 2017 12:49 PM
> *To:* SDIY
> *Subject:* [sdiy] Expo in one chip?
>
> Expo conversion is require in almost all VCO, VCF and VCA circuits.
> Matching transistors and getting the right tempco resistor to be touching
> them so they are the same temp is a pain.
>
> Has anyone ever made an expo conversion chip that had everything required
> in one package? Is it still available?
>
>
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