[sdiy] Wondering about function generators for envelopes

[Metrophage]

Not what I have been pondering, but that's a fun and economical looking
circuit.

CJ

--- Aaron Bader <sparked at zadzmo.org> wrote:

> On Thu, 7 Jul 2005 12:38:16 -0700 (PDT)
> Metrophage <c0r3dump23 at yahoo.com> wrote:
> 
> > Say, for instance, four (or more) points with controls for how
> quickly
> > we go between them, amplitude of each point, and ways of describing
> > various transitions or interpolations between them.
> 
> I actually made a sketch of something that did just that a few weeks
> ago, but haven't really had time to play with the idea further:
> 
> http://www.louisville.edu/~adbade01/arb-wave.png
> 
> Use a presettable down counter and you could choose how many points
> you
> want to use, but, that would also require wiring the points
> backwards.
> The only flaw in this design right now is amplitude modulation would
> effect frequency; It was included because it's a trivial to implement
> and possibly useful enhancement.
> 
> My plan was to use a 4046 to phase-lock-loop it to an oscillator,
> thus
> making an arbitrary waveform in the audio range. Choose a higher
> value
> capacitor and it would work quite well as an lfo, or some way to make
> it
> stop after hitting a preset number of points and continue after the
> gate
> lets off and you'd have a good envelope generator a-la CZ-1000 or
> DX-7.
> 
> I never thought about different transition types, but, I guess you
> could
> take output from the amplitude control for a squarish shape, from the
> capacitor for a triangular shape... getting a good exponential
> decay/gain would be interesting but I'm not sure where to start with
> that.
> 
> -- 
> 
> "Not a bird not a leaf not a sound/And well after the close of time" 
> 	--Front 242
> 
> Public Key: http://sparked.zadzmo.org/
> 
> 

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