CA3046 vs CA3086?

[Marjan Urekar]

jorgen.bergfors at idg.se wrote:

> I have built the saw to triangle converter but I can't get the triagle wave
> quite symmetrical. Also there is a glitch at the peak.

That glitch is common in such (simple)converters using transistors.I
don't
have this schematic handy but it's something like two transistors (with
or
no buffer?) and first one being in saturation and then having negative
feedback
with emitter resistor (or something,I'll better go and learn for my
analog
electronics exam :).Glitch is the result of changing states of
transistor.
Not shure,but I think you can't get perfect symmetry with such
converter.

> I have tried many different transistors (including the specified 2N3904) and
> experimented with different resistor values, but that doesn't change the
> waveform much.

Maybe matching transistors for better results,but if second transistor
is 
just buffer then it doesn't work too

> Do you know if a genuine Moog 921B has these problems with the triangle
> waveform? If it does, it could be considered part of the "sound" and probably
> should be left as is.

Someone mentioned (here or AH) that he had scoped minimoog triangle
waveform
and that there is glitch too ( supposing that tri converter is like the
one 
in 921) and that that can be one of the things that make mini sound so
specific
(beside VCF)...

> 
> P.S. by adding a 1n capacitor in series with a resistor between the base and
> emitter of the first tranny, the glich can be reduced. But Moog didn't do this
> -- at least it's not in the schematics.
Someone should know this better than me...


marjan