Yamaha CS80

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Fredrik Segerfalk
www.analogsweden.com/blog

The Old Crow wrote:
>
> 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 <http://www.cs80.com/VCO153_pic.gif>
>
> Crow
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