[sdiy] Pitch detector Envelope follower!

[KD KD]

> 2011/11/3 Harry Bissell <harrybissell at wowway.com>
>> Analog pitch tracking absolutely works 100% for amplitude stable regular
>> waveforms (such as sine, triangle, square,
>> ramp with 2nd harmonic less than the fundamental.  Hey, no problem :^)

Yes that we know but the dude does not so perhaps one way to fool him would
use steady waves  and quickly grap his money and run before he can feed any
irregular waves into the blody thing!

> which is handled quite nicely in the MS-20 (the queen of tachometer
>> circuits). They use three sections of a four-gang pot to make a low pass
>> filter on the input. The more you filter the input, the slower the
>> response
>> but the more accurate. Less filtering is faster but less precise. The
>> fourth section is the ripple filter, you guessed it... the
>> faster the thing tracks, the less ripple is rejected.

I wonder how the Korg  X911 was implemented , have to check out the
schemos  to see...
Hmm its quite a different beast, sampling very low levels.. almost no
filtering...hmm

>> Of course if your customer makes bug music, this might be a feature, not
>> a bug...   :^)

 don't think it matters, it's  gonna sound like bug music anyway.;)

>> I think that Tom Gamble (EFM) was on the right track in trying an MS-20
>> clone substituting a VCF for the lowpass filter and the lag circuit. What I heard then of >>his experiment  (audio) convinced me his design was not yet working, but it should have.  >>I'd suggest the MS-20 is the  closest  to a working 'simple' circuit  that has ever been
>> done.

That's a good idea to try out, i will poke around a bit by using a 2
pole SVF as start.

Fgdfdrrws..