Yamaha CS80

WE STAND AT SALUTE!!!!

this is awesome. a drop-in complete m-board pcb, with BOM, would be so huge......wow.



--- On Wed, 3/18/09, The Old Crow <oldcrow@...> wrote:

From: The Old Crow <oldcrow@...>
Subject: [yamahacs80] VCO153 project in board test phase
To: yamahacs80@yahoogroups.com
Date: Wednesday, March 18, 2009, 1:39 AM











    
              Hey folks, its been a while, but I have this thing in testing right 

now.  This is an equivalent circuit to the IG00153.  This differs from 

my MOTM-style modular 153 oscillator in that it is strictly the VCO IC 

with a ramp output, linear CV input, current bias input (FT) for octave 

select and exponential modulation (vibrato) input.  It can use the 

original M-board FET and charge pump capacitor, or those can be removed 

and local ones installed.  I made this mainly to see about replacing 

things at the chip level, but not relying on custom devices.  It is 98% 

SMT parts, with only 3 parts left through-hole for the moment (mainly to 

swap things and see how the specs change).  It no longer needs an input 

offset trimmer, or external frequency compensation of the input summing 

amp.  The DIL-16 footprint in the middle of the board is used to install 

it into an actual IG00153 socket. Generally it is low-profile enough to 

fit between M boards (it does in my CS-50).  It has internal temperature 

compensation of the charge switch and comparator, making it much more 

stable than the original device.  The charge pump core circuit runs on 

its own internal 10V reference supply.



Eventually I want to craft the entire M-board from standard circuits.  

The waveshaper is done (it is the one I made for the 153 module).  The 

EGs are done.  The filters are done.  I know how to build the VCA, thats 

next.  In any case here is an image of the board, a bit larger than 

actual size.  More later...



http://www.cs80. com/VCO153_ pic.gif



Crow

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