[sdiy] I need a 909 kick circuit analysis

[TooManySynths]

Hi All,

I looked through the archives and I can't seem to find
much detail on the 909 kick.  I have a schematic of
the kick (sidenote, none of the 909 schematics links
work, are they on line somewhere?) and I'm trying to
make some sense of it.

In  particular, how is the VCO working, and what is
the role of Q11? I see that it bridges C4 with R51 on
what appears to be the start of the trigger. I'm
assuming the trigger is a positive going pulse.  Also
is the "Attack" circuit simmilar to other drum synths.
 What I mean is, I see that they are injecting noise
into the "Attack" circuit, does "Attack" just control
the level of a noise blip.  I haven't touched my 909
in a while and it's not sitting in front of me.

Any general explanation of the various components of
the 909 kick would be appreciated.

Thanks
Daryl



__________________________________________________
Do You Yahoo!?
Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger
http://im.yahoo.com