>The main problem is not this part of the circuit but
> the "anything"-to-rectangle converter. "Anything" means any kind of
> monophonic sound source, like human voice, guitar, bass, flute,

violin ...

i do this often with bass and vocals, and have found the a160 clock
divider to be an excellent anything-to-pulse converter - apart from
the fact that i can't get the original frequency out of it, just
sub-octaves :)

it also works fine with most osc waves, although it does "jam" when
using square waves (i haven't done this with a vco for ages, so i hope
that's right).

i haven't yet managed to set up the patch you suggested to set up a
linear tempo/cv curve - the cv changes are a little too small (but i
must confess that i got totally distracted by the joys of a super
-lofi pitch-to-cv coverter :))

cheers,

stu