from Harvestman : http://www.theharvestman.org/r1983.php
Sawtooth-core VCO with 1V/octave tracking, manual octave switch, voltage-controllable pulse width modulation, and both linear and exponential frequency modulation. This is a Eurorack packaging of the Polivoks Generator circuit, authorized by the instrument inventor Vladimir Kuzmin. The exponential converter and temperature compensation circuits use original NOS Soviet integrated circuits. The hard sync is very sharp and the distortion on the triangle output is nice.The Harvestman Polivoks vcg demo Harvestman polivoks VCG + VCF by idiot design ~ davidh
first Saw, then Tri, and Square.