2 modules ideas

[Don Tillman]

   Date: Tue, 15 Aug 2000 11:54:34 -0500
   From: "Grant Richter" <grichter at execpc.com>

   The Buchla Model 148 Harmonic Generator did this.  From the catalog
   "Generates a fundamental and its first nine harmonics (Harmonic
   Numbers 1-10 (sic))".

   The method used was to start with a triangle oscillator, followed
   by cascaded non-linear function generators to generate harmonic
   triangles, then convert the triangles to sines with the classic
   JFET waveshaper.

   The 3X NLF must have used some of that Buchla voodoo.  How you get
   a 3X nice triangle wave from a 1X triangle wave, is not obvious to
   me.

I remember an "Ideas for Design" entry in Electronic Design magazine
many years ago, mid 70's, for a triangle wave frequency tripler built
from 2 transistors.

But anyway...

I think this frequency-multiplying-a-given-triangle-wave approach is
not optimal.  Sure it's possible, but it's a lot of work, and any
inaccuracies are going to show as uneven waveforms, and errors will be
worse for the higher harmonics, leaving a lot of the fundamental in
each harmonic.

It's a lot easier to build N sync'd triangle wave oscillators, all
running with a common current source, and with capacitor values of c,
c/2, c/3, c/4, etc.

  -- Don

-- 
Don Tillman
Palo Alto, California, USA
don at till.com
http://www.till.com