Voltage Controlled Oscillator (VCO) / Low Frequency Oscilator (LFO)
Oscillator is the most basic module from which the sound begins. It can create audio frequency signal and also low frequency modulation signal for controlling another parts.
Oscillator has three waveforms: triangle, square (pulse) and sawtooth. Each of the output channel has two identical output and indicator LED. You can switching output level between unipolar (from 0 to +5V) and bipolar (from -5 to +5V)
Image of the latest released version of the module. This is not the final product, development is in progress.
You can control the frequency (pitch) by coarse and fine knobs, and also with external control voltage (CV).
- Pitch input has 1 V/Oct scale, you can tune scale by 1 V/Oct tune trim
- FM input has variable scale, controlled by Fine/FM knob in FM mode
Also for the square wave we can control pulse width by knob and by external CV.
Each input channel has two CV input pins. Signals from both inputs are summed.
Known issues
- board outline update is needed
- triangle output not implemented
- in FM mode changing FM amount affects base frequency
- expo converter has narrow range and high temperature sensitivity
- output voltage range is not quite accurate
