[sdiy] pulser mod and demo

[Grant Richter]

Hi Ian,

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

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.

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?

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.

> From: Ian Fritz <ijfritz at earthlink.net>
> Date: Mon, 23 Jun 2003 11:02:12 -0600
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] pulser mod and demo
> 
> Hi all --
> 
> It seems like a good idea to have at least a couple of parameters to vary
> in a waveshaper.  (As seen by the great domos of Jim's multi-break-point
> shaper that were recently posted.)  So I've reconfigured the 5Pulser shaper
> to allow a second kind of waveform variation.
> 
> In this reincarnation two comparitors are connected to the LM3914 outputs,
> the first to outputs #1, 5 and 9, and the second to ouptuts #3 and 7.  The
> first set is always output at 5 V peak, whereas the second set has a
> variable (voltage controlled) amplitude between +5 and -5V.
> 
> The effects of the pulse-height modulation are a bit more subtle than the
> main pulse-number modulation,  but there is a large range of useful new
> timbres available.  A second demo showing this added modulation capability
> is now up at my web site:
> 
> http://home.earthlink.net/~ijfritz/xfer.htm
> 
> Ian
> 
>