[sdiy] pulser mod and demo

[Ian Fritz]

Hi Grant --

>This sounds very nice just as is. If I may offer a humble suggestion in the
>name of good fun.

Well, I appreciate your thoughts.  Certainly there seems to be many other 
ways to apply the LM3914.

>In the write up for the generalized monostable resonator in Electronotes,
>Bernie points out that, in the most abstract sense, a resonator is simply a
>device which gives multiple zero crossings out for a single zero crossing
>input.

Right.  That work seemed to be more aimed at fixed formants, i.e., the 
VOSIM-type methods.  Certainly we could trigger different monostables off 
of the 3914 outputs.  This would give monostable *spacing* that scale with 
frequency, but with *widths* that are frequency independent.

>It would seem possible to model a decaying sinusoid impulse response using
>the LM3914 waveshaper. That would be alternating + and - peaks with a
>decaying pulse amplitude. I would think, that by varying the LM3914 resistor
>ladder references, which is equivalent to varying the input slope, you
>should be able to vary the output pulse spacing. This should work OK using a
>sawtooth input?

Sure, you could do that.  My unit sort of does that, except the amplitudes 
are constant rather than decaying.

>The upshot of this would be a function generator which produces waveforms
>similar in nature to a swept resonant filter. This could sound quite nice,
>and have musically useful control axis. This would only be one of
>potentially large number of waveshaper settings for your design.

Yes, I can see where that would be more like a resonant filter than what I 
have.  It would require separate processing for each pulse (to get the 
decaying amplitude), which would be quite a bit more complex than what I 
built.

   Ian