triangle VCOs and Buchla designs

[mark verbos]

of course.

i also just found a reference to the fact that a 3080 can ONLY use a PNP
based exponential converter. the Buchla actually uses NPN. So this limitation
is only in the 3080 not the triangle design in general. I think I will try to
use an SSM matched PNP and 2 2n3565 in there and see how it goes. The
original used an Analog Devices AD821 and an AD811 as the exponential
converter. That is a little too  obsolete for my taste, but i guess a 2210
and a 2220 will work. right?

Terry Michaels wrote:

> Message text written by mark verbos
> >ANYWAY, I am now wondering if there is any real advantage to going
> descrete
> or is it just because OTAs were expensive or rare in the 70s. Has anyone
> ever
> tried both? When I start my Buchla 259 clone should I just use a 3080?
> anyone?<
>
> Hi Mark:
>
> Here is one possibe answer.  You can't trim the current mirror ratio in a
> 3080, so you often end up with a slight asymmetry in your oscillator
> waveform.  The Buchla descrete design has a trim for that, at least at the
> low end of the frequency scale.
>
> Terry Michaels

--
mark verbos

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