please help. AD/AR envelope generator

[Grant Richter]

End pulse is kind of a misnomer. Neither the Buchla nor Serge units
actually have a pulse output. It is just a comparator with a 150mv threshold
that goes high when envelope output is below 150 mv. That way it can be used
as a gate delay also. This will automatically become a pulse in recycle
mode. If you like, have both, this signal and a jack with a 0.001 to it for
trigger output only.

Every envelope generator has an Set/Reset flipflop in it. Both outputs
should be brought out, one for square waves and one for quadrature
triggering. The not Q output goes high at the end of the attack phase of
envelope 1, which triggers envelope 2. The end pulse of envelope 2 triggers
envelope 1 again and the two signals can be used for quadraphonic panning
(creates a circle pan in quad space).

Both the Buchla and Serge universal slope generators uses a CA3080 in an
integrator circuit. The one circuit that actually improves on the design is
Chris McDonalds for the Mini-Modular (see his personal page for schematic).
This uses a 3080 as an integrator with the integration voltage switched by a
CD4052 into the expo converter. The design is an ADSR, but you can just skip
the gate logic and use the S/R flipflop in the 555. Add a three position
switch, bring out both polarities of the S/R flipflop, add an "end"
comparator (hint 100K/1K = 150 mv and 0.01 cap for positive feedback) and
you have a Buchla Function Generator/ Serge USG in 3 chips (3080, 4052,
TL074). It will work better than the originals too.

> From: mark verbos <a0284520 at addcom.de>
> Reply-To: owner-synth-diy at node12b53.a2000.nl
> Date: Thu, 30 Nov 2000 06:25:54 +0100
> To: synth DIY <synth-diy at node12b53.a2000.nl>
> Subject: please help. AD/AR envelope generator
> 
> Hello////
> 
> i am trying to create a voltage controlled ad/ar envelope generator.
> with end pulses and a quadrture mode like the Buchla 281. I am basing it
> around the VC core Jürgen Haible has on his webpage. I built it and it
> doesn't work. I am stumped. Can someone who understands this kind of
> thing have a look at my design and give me a pointer or 2?
> 
> the schematic is here.
> 
> http://www.simple-answer.com/ad-ar.jpg
> 
> any help would be GREATLY appreciated.
> 
> --
> mark verbos
> 
> "if you want something done right, build it yourself."
> 
> verbos at simple-answer.com
> www.simple-answer.com
> 
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> 
>