Schlappi Engineeing Angle Grinder - Quadrature Sine Wave VCO / State Variable Filter

Quadrature sine wave VCO with four phase related outputs: 0°, 90°, 180°, 270° HIGH range from 10Hz to over 20kHz LOW range from 0.1Hz to over 500Hz Tracks volts per octave at the V/OCT input FM1 is selectable linear or exponential FM via jumper on back FM2 is additional exponential V/OCT jack With no input GRIND section provides voltage controlled harmonic content With input GRIND section compares each phase against GRIND IN signal Each slider subtracts the compared signal from the input signal, creating complex waveshapes When GRIND is fed into the SPIN section the outputs become a state variable filter DAMPING counteracts the oscillation and allows an external signal through When filtering the four phase related outputs are: LOW PASS, BAND PASS, HIGH PASS, and INVERTED BAND PASS When filtering the GRIND section is a nonlinear feedback network for harsh and unpredictable timbres The four phase feedback paths can be separately voltage controlled The INJECT jack can be used as a second input for either audio or CV, bypassing GRIND All analog OTA based design 81 mA +12V 78 mA -12V 0 mA 5V