8hp 12dB/Oct Voltage Controlled state-variable Filter

The SVF12 Module consists of three boards

SVF12 Front plate: https://www.pcbway.com/project/shareproject/SVF12_F_Board_7375cd3b.html

SVF12 A-Board: https://www.pcbway.com/project/shareproject/SVF12_A_Board_41b4c3dc.html

B-Board: This project.

Features

• Two Inputs IN (DC-coupled, allows for audio and CV processing)
• Volt per octave Input V/O
• Ping Input PING
• Self-Resonance switch FILT/OSC
• Lowpass LP Bandpass BP Bandstop(Notch) BS and Highpass HP outputs 

Oscillator mode

The module can be switched from Filter mode (Switch in the FILT position) to Oscillator mode (Switch in the OSC position), turning the module into a musical sine-cosine quadrature VCO. This can produce clean sine waves on the outputs with no input, a mode called self-oscillation. The sinusoidal signals of LP, BP and HP are phase-shifted 0, 90 and 180 degrees. With a trimmer on the back of the module, the V/O input can be tuned to allow for volt per octave tracking

Ping Input

By sending a rising-edge signal like a Gate or a short Pulse to the PING input, the filter core gets excited and creates a damped oscillation. The length of this oscillation is controlled by the resonance (RES) setting.

Power

A standard 10-pin Eurorack power connector is used (Red Stripe indicates -12V (negative twelve volts)). The module is internally running on +/-9V to stabilise the volt per octave tracking.