[sdiy] Yamaha IG00159 internals

Nicholas Keller niroke at tampabay.rr.com
Tue Jan 17 22:49:47 CET 2017

That's what I was hoping.  There are some interesting notes on this page about the unique curve to the envelopes, but I don't understand most of it. 


The PDF that was posted earlier in this thread seems to confirm your suspicions about the contents of the chip, but I don't know how to create the sequential switch. 

> On Jan 17, 2017, at 2:58 PM, Mattias Rickardsson <mr at analogue.org> wrote:
> Yamaha's envelope chips are odd in the way they use an extra VCA chip
> just to implement the envelope itself. I'd expect them (all of the
> Yamaha IG chips) to be very simple inside. The envelope chip probably
> just consists of the little logic state machine taking care of the
> Attack/Decay/Release envelope phases, and routing the input CVs
> correspondingly, letting the external extra VCA chip do the slopes.
> Maybe this chip is already analysed and copied to standard components
> of breadboard?
> /mr
>> On 17 January 2017 at 14:05, Nicholas Keller <niroke at tampabay.rr.com> wrote:
>> Does anyone know of an internal diagram for the IG00159 amp EG chip?  Or has someone made a stand-in circuit for the chip alone?
>> Thanks
>> Nick
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