[sdiy] Pearl Syncussion VCO

[Harry Bissell]

OK I see I missed the point...

The inverter tied with output directly to input will oscillate at a very high
frequency, or may just cue up to the quiescent point where the input is exactly
in the middle of the active region. This could be forming a bias point for the
rest of the circuit.  It should self-regulate to exactly the point that makes the other five inverters
in the same package are most active at.

Note, you need to have all those inverters share the same package for the trick to work.

I did something similar in my EDN "Three Phase Oscillator" idea for design.

Its another linear trick...

(also possible the schematic is drawn incorrectly ???)

H^) harry

----- Original Message -----
From: Ben Barwise <clackjunk at gmail.com>
To: synth-diy at dropmix.xs4all.nl
Sent: Tue, 04 Oct 2011 12:15:56 -0400 (EDT)
Subject: [sdiy] Pearl Syncussion VCO

Hey,

I have been exploring lots of drum synthesizer schematics and I am
currently looking at the Pearl syncussion. I was wondering if someone
could give me a few tips on certain parts I am finding confusing in
the VCO.


I understand the integrator and schmitt trigger and then sort of get
the CV input but I am just completely lost what is happening with that
inverter stuck on the side of that PNP pair at the top - is that just
a good way to tie up unused pins? does this schematic seem a bit
bonkers? because I have traced it from that well known scan hanging
around the internet (why do people bother scanning schematics you cant
read! ) the inverters are guessed as 4069's they may not be.

it is an interesting design anyway,

http://img88.imageshack.us/img88/1884/pearlsyncussionvco.jpg
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-- 
Harry Bissell & Nora Abdullah 4eva