[sdiy] Favourite VCO designs

[David G. Dixon]

> Because even if it were designed by the Romans, you can still build
> it wrong!

Yeah, I know.  I was being a bit facetious.

However, all kidding aside, that's why I design circuits in blocks.  (In
fact, that's really the only way I can understand circuits and schematics,
which is why the ultra-dense "stuff it all on one page" approach really
annoys me.)

The VCO consists of the following blocks: expo converter, saw core, tri
shaper, sine shaper, pulse shaper.  In turn, each block consists of
sub-units, each of which performs a specific task which is easy to identify
and test.  It's really not that hard to debug.  It can even be built and
tested in stages.