Quadrature VCO schematic posted

[Chris MacDonald]

Thanks to some help from list members, I have put together a quadrature
sinewave VCO.  The circuit is based around the Mini Modular 12 dB
state-variable filter, with zener regulated positive feedback for
oscillation.  I believe that Harald Bode came up with the original
circuit concept.  Please correct me if I am wrong on that.  If anyone is
interested, there is a pdf of the schematic available on my DIY site:
http://www.evenfall.com/diy/index.html

-Chris MacDonald