tri2saw (was:commercial synth circuits)

[Martin Czech]

> What about this method (haven't tried it yet):
> Build a triangle VCO, and use an additional transistor 
> (matched) in the expo converter to get a second control 
> current. Use this current to charge a second capacitor,
> and discharge this capacitor every time when the triangle
> has a positive zero crossing. Shouldn't use more components
> than other converters, and all you get might be a little amplitude
> error in the saw wave.
> 
If one uses a design with ota as current polarity switch (ca3080 app.
note) it would be possible to use a dual type, there you are, this
should be an allmost perfect current mirror.  No need to touch the expo
converter. I wonder if the toggle-the-tri-and-add-a-square method is so
bad at all. How does it the curtis 3340?  This is a tri osc. Must be
the same circuit. Any glitches could be filtered out. If you use a
simple 6db lowpass with "reset" at the right square toggling point, so
that the fast edge is not filtered.

m.c.

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