An oscillator shifts a value, such as volume or tone, between two levels, usually with a repeating pattern.
In Patchwork, one example of oscillator use is the LFO Modulator device, which uses an oscillator to continuously adjust controls on other devices.
Other Patchwork devices use oscillators to shape their output. For example, the vibrato control on the Patchwork Instrument Player uses an oscillator to rapidly shift the pitch of the audio output.