[sdiy] PLL examples

[David Moylan]

I believe this is correct.  There are two comparators and two peak
followers, one for positive peaks and one for negative peaks.  The peak
followers basically set a varying threshhold to the comparators, so as
the signal increases the threshhold does as well as as it decays the
threshold drops.  The comparators outputs are connected to set/reset. 
I've seen this exact method in other pedal schematics as well.

I haven't played with this circuit too much (besides checking out the
OC-2 a bit), but if you wanted to I'd buy an Arion octave pedal which
appears to be a clone of the Boss and is $15 bucks right now on
Amazon.com.  then hack away.

Dave

JH. wrote:

>>Wouldn't it be necessary to limit this to "real" peaks somehow?
>>
>>Thinking of e.g. a low pass filtered square wave - formally, there are
>>lots of peaks due to ringing at each edge.
>>    
>>
>
>After a positive peak, a flipflop is set, and only with a negative peak
>of enough size, the flipflop is reset. No chance for ringing to trigger
>anything, unless the ringing is larger than the fundamental. 
>"Enough size" is determined with lossy peak detectors,
>which "remember" the size of the previous peak.
>
>This is just from memory - analyse that Boss circuit to see if it fits.
>
>JH.
>  
>