[sdiy] Discrete OTA

[Neil Johnson]

Roman,

We love you *hugs* :))))

Here's the decoded image online for all to enjoy:

http://www.njohnson.co.uk/roman_sowa_0drift.gif

And for reference here is the original email text (less mime attachment):

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To: synth-diy at mailhost.bpa.nl,
From: Roman Sowa Roman.Sowa at WizjaTV.pl,
cc:
Subject: low-temp-drift ssm2164 VCO
Date: Mon, 30 Aug 1999 13:09:45 +0200

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Hi all,

Let me have the pleasure of presenting new (for me)
VCO with *no* tempcos and *no* heater, but still
not bad in terms of temperature stability.
This circuit was born in discussion with
Paul Maddox in private mail.
It is based on my beloved SSM2164 quad VCA chip,
and it's ten times more stable than my last VCO.
It isn't stable as a rock, but still enough for me
to make next module with it.

I did thermal tests using finger for heating, and
blowing air for cooling, so I guess temperature
change was about 10-15 deg. Over this range
the frequency drifted like this:

4Hz 0,2%
100Hz 0,5%
550Hz 0,1%
1.5k couldn't notice
11k 0,3%

Any comments, and improvement tips appreciated

Roman

PS It's only 5K file. Hope you don't mind...
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Cheers,
Neil

On 7 April 2014 09:48, Roman Sowa <modular at go2.pl> wrote:
>
>>> Incorporating the expo converter is handy, but the Osamu
>>> Hoshuyama temperature compensation is a fairly compelling
>>> argument for the 2164.
>
>
> all this recent talk about 2164 Osamu's compensation made me finally go and
> seek for this circuit. What a surprise it was when I saw it's basically the
> circuit I originally posted here in 1999, only refined to find the magic
> number of 0.27V bias.
>
> Well, the multimania site, where I used to show ideas like that, does not
> work anymore, and I didn't move all to synth.net when it started, so there's
> only email atached GIF that's out there. Another lesson that if something is
> not published in internet, it does not exist.
>
> It's not rocket science and I'm not claiming any rights to this very simple
> circuit that is so obvious to come up with. But still kinda feels like
> Antonio Meucci...
>
> or maybe I'm just having a bad day today...
>
> Roman
>
> _______________________________________________
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