Minimoog VCF

[terry michaels]

Hi list members:

A few weeks back I posted a general message asking the question: are the
reports of the Mimoog VCF drawings on the net containing errors correct? 
During the early production of the Minimoog, Moog included a set of
drawings with each new unit shipped.  The drawings were obviously copies of
the original circuit designs, printed on engineering sheets with a "R.A.
Moog Co." title block and a file number.  The drawing shows the complete
circuit on the VCF filter Printed circuit card: the filter core circuit,
and the pots, switches and other circuitry that tie in to the filter
itself.

I looked at the drawing posted at
http://www.hyperreal.org/music/machines/manufactures/Moog/MiniMoog/schemati
cs/minifilt.gif 
along with Sean Costello's site http://www.seanet.com/~costello.
Without knowing the original source of this drawing, I have to guess this
is a page out of a Moog owners manual that probably accompanied later
production units, or a later release service manual.  I personally never
have seen such a manual, but it looks like Moog re-drew the original
circuit, without the title block.  Unfortunately they printed only the
heart of the filter circuit, and left out the peripheral circuits needed to
make the circuit work.  This might be the source of the problem people have
had in duplicating this circuit.  I compared the two drawings, aside from
the peripheral circuits shown on the title block drawing and not shown on
the second drawing, they are the same, except for a few resistor and
capacitor value changes.  I did not see any gross errors that would make
the second circuit non-functional.

Terry Michaels