Circuit Analysis of Zorgtaver? How to add Octave-up?

[Zwachi]

Hi folks!

I tumbled across Zorg's pedal page and took a look at the Zorgtaver, an interesting octave circuit with 2 octaves down, effects loop and inverting options.
There are a bunch of buffers for isolation and some parts I don't understand right now.
Maybe someone could be kind enough to explain roughly what is happening step by step?
As far as I understand:
U1A is a buffer, U1B a gain stage to drive the envelope and power up the signal for the CD4013. U1C seems to be a filter stage. I don't get what the stages of U2 exactly do but I think they form a square wave for triggering the CD4013.
U3 stages act as inverters and buffers. U4D is a summing stage and U4C a variable low pass filter. U4B again summing stage for dry and octave signals.

What is the envelope with the LDR good for? The more signal the envelope gets, the less the resistance of the LDR, so it is limiting the time of the octave signal getting trough?

I really think of building this one and would like to know how to add an octave up effect as well?
Probably the best way is simply adding a transformer with diodes? Any other advices?

I already built the "Into the Unknown" circuit and Bit Commander but I'm still not completely happy with the octave sound they give me.


complete documents: http://www.zorgeffects.com/images/Manuels/Zorgtaver_Schematic.pdf

[Zwachi]

How about a CD4093 Schmitt trigger for the octave up part?
Like a Escobedo PWM a external LFO can modulate the pulse width and with a switch i could toggle between PWM and octave up sounds.

I simply would locate this circuit between the "Square" marks as there already is a square wave signal.

If I look at the control knob layout, there's still some space for two more controls?

Any suggestions for two additional controls? 

[R.G.]

Looks to be a first principles octave divider with a compressor in there. There are input buffers, filters to cut something or other, a couple of rectifier circuits, and the usually digital flipflop to generate the one and two octaves down.

There's no obvious way to get an octave up that I see. Of course, you could add on a full wave rectifier circuit after the bufferning and filtering and make yet another thing to throw into the mix.

You could, as Zwachi says, hook into the square wave and do some things with it, I guess. Its very special cased in doing that.

I posted some stuff about phase locking to a square wave and generating octaves up a ways back in the forum. Getting a cleaned up square wave is a first good step for that.

[Zwachi]

Hi R.G. and thanks for your answer!

Things getting clearer to me. I played around with my Bit Commander and realized that the squared signal mixed with the octave sound is essential for a good feel on playing. That's why I would leave the "Square" path as it is and add another path for octave up.

The LDR seems to be some sort of signal limiter to cancel unwanted noise from the octaves when the strings don't swing.

What would be really nice is a ring modulator circuit that could be mixed with the octave circuits.
Is there an easy way to add it to the square wave?