[sdiy] Bernie Hutchins CA3080 VCA

[Gene Stopp]

No typo - Electronotes # 61, I think? (from memory, scary huh?)
 
It's a "two-chip" VCA. Pin 4 of the 3080 does not go to -15 but is instead
driven by the control input op-amp. It's from a Walter Jung design
originally I seem to remember (scary again. huh?), and he is using the 3080
as a transistor array rather than an op-amp with a gain control pin. The
guts of the chip don't care what kind of schematic symbol you use!
 
I used this design for the ASM-1 since it's such a cool linear VCA. However
I can't explain the theory as well as the original Electronotes article. It
was several pages in great detail of how a 3080 is built inside.

Best Regards,

- Gene

-----Original Message-----
From: Fahl, Romeo [mailto:RFahl at extensis.com]
Sent: Wednesday, December 19, 2001 12:59 PM
To: 'Massimo Ischia'; synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] Bernie Hutchins CA3080 VCA 



Perhaps a mislabelled schematic?  Which issue of Electronotes is it in?

Romeo

 

-----Original Message-----
From: Massimo Ischia [mailto:prophet at libero.it]
Sent: Friday, January 18, 2002 10:12 AM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] Bernie Hutchins CA3080 VCA 



Hi,
 
Can anyone explain me how works the strange Bernie Hutchins CA3080 VCA (that
with control signal on pin 4)
 
Massimo Ischia
Software Dpt

Far Systems S.p.A.
Via Fornaci, 35, 38068 Rovereto (TN) - ITALIA
Tel. +39 0464 485333 - Fax. +39 0464 485334
Internet: www.farsystems.it <http://www.farsystems.it>  <
http://www.farsystems.it <http://www.farsystems.it> >  
E-mail  :  prophet at libero.it <mailto:prophet at libero.it> 




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