What are non-sinusoidal oscillators generally called?

Non-sinusoidal oscillators are primarily referred to as relaxation oscillators. This classification arises from their behavior in creating waveforms that exhibit sudden changes in voltage or current levels, followed by a slower return to an equilibrium state. Relaxation oscillators are characterized by their ability to generate a repeating waveform that is not smooth and sinusoidal in nature, such as square waves or sawtooth waves.

These oscillators operate on principles of energy storage in reactive components like capacitors or inductors, accompanied by a nonlinear feedback mechanism that establishes the oscillation characteristics. The term "relaxation" reflects how the circuit returns to its initial state after being perturbed, such as through charging and discharging processes.

Other options present types of oscillators that may produce sinusoidal outputs or are associated with different operational characteristics. For example, harmonic oscillators typically refer to systems that can produce pure sinusoidal signals. Linear oscillators emphasize linear responses and stability, while digital oscillators pertain to circuits that generate digital signals or pulse modulation. Hence, the designation of non-sinusoidal oscillators as relaxation oscillators is precisely aligned with their unique operational and output qualities.