[sdiy] more pitch shifter thoughts

[Roy J. Tellason]

I got to thinking about this subject some time back,  and came up with some 
thoughts about things that may or may not work,  I never did get around to 
playing with this idea.  Maybe you all could tell me why it wouldn't 
work?  :-)

Suppose you took a PLL circuit,  one input to the phase comparator would be 
some filtered version of your input signal.  (The filtering would be one of 
the tricky parts,  I guess.)  The PLL is also running a top-octave chip,  and 
maybe (maybe not?) some divider stages,  depending.  Things get set up so 
that the lowest "note" available comes out at the same pitch as the filtered 
version of the input signal...

Then you've got the rest of the outputs,  the other "notes",  and maybe 
octave-related versions of it,  all of which are going to be square waves of 
course (unless you get one of those oddball top octave setups that produces 
an assymetric output waveform for higher harmonic content),   but in any case 
more filtering is going to be needed here...

Take a selection of those outputs and you've got "chords".  Mix them,  do 
whatever...

Does this sound like it'd be possible to make it work at all?  If not,  why 
not?