[sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated outputs different

[David G Dixon]

Such a "zener bridge" is at the heart of every Dixie, Rubicon, and Atlantis
VCO.
 
The idea is that the zener bridge gives more symmetrical results than two
back-to-back zeners.  However, it relies upon the assumption that the two
pairs of regular diodes are identical.  This is probably more true than
assuming that any two zeners of the same nominal voltage are identical, but
it is still an assumption.


On Wed, 28 Nov 2018 at 10:18, Steve Lenham <steve at bendentech.co.uk> wrote:


...
If, however, it is only bipolar symmetry that you are after rather than 
an exact level, consider putting a single Zener inside a diode bridge. 
That makes the positive and negative clip levels identical.


Sorry to be late on this ball, but I remember seeing (and saving) a
schematic example of this, a single zener surrounded by 2 or 4 diodes in
some bridge configuration - but now I cannot find it. The main point of it
as I remember was to get a very symmetric output by avoiding having more
than one zeners (since they are rarely as well matched as regular diodes),
and instead use the same zener as the level reference for both the positive
and the negative side. I guess a TL431 could give an even better result.

Can anybody give a pointer to where this has been described?

Thanks :-)

/mr

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