[sdiy] help adding a 1/v oct input to an MS20/50 vco core?

[Harry Bissell]

iirc you should check the archives because some years back this was discussed in
great detail. I think that Jurgen Haible has some info on his clone of this VCO
on his site as well. The gist of it was they used linear tracking for the keyboard
and expo only for modulation, so the expo converter does not have to be super stable
or accurate. If anyone can remember the thread more accurately, buy Dan a letter :^)

H^) harry
----- Original Message -----
From: dan snazelle <subjectivity at hotmail.com>
To: synthdiy diy <synth-diy at dropmix.xs4all.nl>
Sent: Sat, 20 Aug 2011 21:13:38 -0400 (EDT)
Subject: [sdiy] help adding a 1/v oct input to an MS20/50 vco core?

Tonight I got a Korg Vco built on the breadboard.. 
just the CORE..


.i did not want to deal with building the expo until I KNEW I could get it working.

it sounds great!

for now I am just controlling the pitch with a resistor into the FET (q5 on this schematic)


http://www.korganalogue.net/korgms/images/service/ms20/circ1.gif



 which connects to a pot going to ground and +v

my question is this....
Do i need to build the transistor pair OPamp hz/v converter Korg shows
 on the schematic or can i plug ANY old regular NPN pair expo converter into the bottom of Q5?

thanks for any help!








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-- 
Harry Bissell & Nora Abdullah 4eva