Oscillator / VCO
Oscillators are a critical part of a Eurorack system, and they can take on a number of different forms. They can be either analog or digital, and many can toggle between audio and LFO ranges, allowing them to perform either function. s mentioned previously, oscillators fluctuate back and forth between positive and negative voltages. If they cycle with a frequency between 20 Hz and 20,000 Hz they will be audible, below that range they are considered LFOs, or low frequency oscillators.
The shape that these cycles take is referred to as the wave shape, and this determines how it will sound. This is referred to as the Timbre of the sound. A sine wave is the most pure tone as it produces a single frequency with its oscillations. Other wave shapes introduce harmonics above the base frequency, or fundamental, which makes the timbre more complex. For example, a sawtooth wave has a harmonic at every multiple above the fundamental, with each harmonic half as loud as the one below it.
Analog oscillators have a warm, musical character that makes them very desirable. Digital oscillators have a level of flexibility and recall that analog oscillators cannot offer.