[sdiy] Tri to Sine Shaping - Another Way

[Scott Gravenhorst]

I experimented with using CMOS 4069UB gates to do sine shaping.  When
operated as linear amplifiers, they tend to distort a quarter cycle
triangle wave ramp into a quarter cycle sine like curve.  If you provide
the right amount of input amplitude and the right amount of gain (both of
which were discovered experimentally in my project) you can get an
approximation that sounds very much like a sine wave.

This converter wants to see the input tri signal centered at a point
halfway between Vdd and Vss.

The whole project is here:

http://home1.gte.net/res0658s/fatman/saw_to_tri_converter.html

with a demo here:

http://home1.gte.net/res0658s/fatman/sg11052001a.mp3

The bass line was done with the project above.

The rightmost gate does the tri to sine conversion.  This project is a saw
to tri converter and the output gate was tossed in there on whim, it worked
very nicely and is really darn simple and inexpensive.  I have done
absolutely no measurement regarding it's sine wave accuracy.  All I can go
by is what it sounds like.  YMMV.

---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.