Don's interpolating scanner

[Don Tillman]

   From: "jhaible" <jhaible at primus-online.de>
   Date: Sun, 3 Jan 1999 00:14:40 +0100

   Congrats to Don for further improoving the Scanner idea !

Thanks!

   Now I hope you will soon come up with a ready circuit for the full
   Hammond Chorus emulation !

I have some thoughts on emulating the Hammond Chorus; it's a very
interesting problem.  It requires some diagrams, so there'll be
another article soon I guess...

   I really like the idea of a smooth, and even variable transition. 
   Should have a real advantage in waveform generation.

Yeah, the biggest practical use for controlling the transition curve
shape is probably in waveform generation.

I've drawn up some ideas for voltage-controlled transition curve
shape, but I can't imagine a use for it right now.  Just a little too
featureful.

(Wait a second...  Using the scanner for waveform generation, changing
the transition curve shape is effectively a zero phase shift low pass
filter.  Hmmm...)

   You wrote about transistor matching. Did you simulate temperature
   effects as well ? (If there is a temperature effect on the waveform,
   one might compensate it with the shape control voltage ...)

The temperature effect is, I think, just a scale issue.  The scale of
the control voltage's range (the distance between the transistions)
is directly sensitive to the temperature change in degrees Kelvin.  So
like a lot of other synth circuitry, it probably only matters when
you're using this signal to tune a musical pitch.  (That's not going
to happen, right?  Or are there more uses for this thing?  :-) )

   I may have mentioned this before, but I also have worked out a
   simplified all-transistor / smooth transition version of the Scanner.

Nice!

  -- Don