electro-music.com wiki | Schematics / Quadrature Trapezoid Voltage Controlled Oscillator By J Donald Tillman

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DIY | VCO | Trapezoid |

Quadrature Trapezoid Voltage Controlled Oscillator by J. Donald Tillman , the full article on this circuit is featured on the website : http://www.till.com/articles/QuadTrapVCO/index.html ,short excerpt from the description given there :

One of the goals of this project is to create a break with tradition and provide an alternative VCO design with new features and new modes of operation. The VCO is the primary source for sounds and modulation sources in electronic music synthesizers, yet it is often said that the filter is the heart of a synthesizer. This is because there are more available variations in filter designs and each filter design has side effects that create an interesting sonic character. I'll claim that this situation is because VCO designs are too much alike, have been stuck in a rut for a few decades and need to jump in a new direction to be more imaginative and musically useful. So exploring new territory is important.

make sure you check the math and analysis of the trapezoid waveform : http://www.till.com/articles/QuadTrapVCO/trapezoid.html

Schematic is the core of the Quadrature Trapezoid Voltage Controlled Oscillator