[sdiy] Transistor questions

[David G Dixon]

Yes, Roman, but I'm doing my version a little bit differently.  My octave
selector will add 1V increments to the VCO CV circuits, so they will need to
track more or less perfectly over four octaves up to about 6kHz.

>From what I can gather from the original schematic, and from Jurgen Haible's
PS-3200 build, the original octave selector routes the signal from divided
down versions, but I must confess that I didn't really understand how this
was achieved in the original (as it would require that each saw generates 7
octaves, and the slowest ones will look very messy, with all of those steps
and shifts).  Hence, I opted only to generate 4 octaves from each saw, and
use CV to shift octaves on the front panel.

In fact, there are a lot of things in the original circuit that I didn't
understand, and couldn't get to make any meaningful results in simulation.
If I can't simulate it, then I don't build it -- it's just that simple.  So
I'm relying on my own circuits for many of the bits and pieces, and opting
to use ICs for the bigger chunks (AS3310 for envelopes -- there will be two
complete ADSRs per key -- and AS3350 for filters -- unlike the original,
these will have fadeable multimode outputs) to save PCB space -- I got the
chips at a significant discount.


-----Original Message-----
From: Roman Sowa [mailto:modular at go2.pl] 

But anyway, here's a thought - arent PS3100 VCOs tuned at basicaly 
constant frequency, varied only in small amount by LFOs and pitchbend? 
Even if it's +/-2 octaves, I don't see any need for super precise tuning 
scale to start with.

Roman