[sdiy] Multi Segment Envelope Generator

[Michael Ruberto]

when I was performing experiments for my rate level EG I used an LF351 for 
the comparator and found it to be quite stable even without hysteresis.

~M


>From: patchell <patchell at silcom.com>
>To: Tim Ressel <madhun2001 at yahoo.com>
>CC: "synth-diy at dropmix.xs4all.nl" <synth-diy at dropmix.xs4all.nl>
>Subject: Re: [sdiy] Multi Segment Envelope Generator
>Date: Fri, 29 Mar 2002 13:13:25 -0800
>
>     The heart of the circuit is actually just a "glide" (U2A,U3A).  The
>glide rate has an exponential control on it (Q1,Q2).  The reset of the
>circuit is more or less just an 8x2 sequencer.  One channel controls the
>glide rate, the other controls the level it glides to.  When the glide
>level is equal to the glide output, it goes to the next step.  All of
>this, is of course, controlled by the logic.
>
>     The logic could probably actually fit inside of a single 22v10.  The
>problem I have with doing this is I have found the newer pld's to be
>less than rugged.  The logic could also probably be done with a PIC or
>AVR...but, I am too lazy.
>
>     As far as the comparators oscilating...that is one reason I just
>used regular opamps as the comparators.  Less bandwidth.  I used a
>similar comparator on my 8x2 analog sequencer and it seemed to work
>pretty good.
>
>Tim Ressel wrote:
>
> > Jim,
> >
> > This is an interesting circuit. It is similar to an
> > ADSR I tried to make. Basically a 4-segment version of
> > yours. From the schematic, it looks like this is an
> > exponential generator meant for a linear VCO. Yes? If
> > so, it looks pretty easy to make it linear.
> >
> > I had a lot of trouble with the comparators on the
> > version I tried. They tended to oscillate from noise
> > when the inputs were near each other. This caused the
> > logic to go nuts. I never went back to see if I could
> > fix it.
> >
> > Keep on truckin', and keep us informed!
> >
> > --TR
> >
>
>--
>  -Jim
>------------------------------------------------
>* Visit:http://www.silcom.com/~patchell/
>*-----------------------------------------------
>*I'm sure glad Merry Christmas comes just once a year
>* -Yogi Yorgensen
>------------------------------------------------
>
>




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