So there are formula 5 quantum harmonic oscillators (hereafter SHOs for "Simple Harmonic Oscillators"). Cavity resonators are widely used as the frequency determining element in microwave oscillators. All real oscillators have phase modulated noise components. Other analogous systems include electrical harmonic oscillators such as RLC circuits. They are used in electronic oscillators and amplifiers, particularly at microwave frequencies. Commonly used VCO circuits are the Clapp and Colpitts oscillators. These are known as quantum harmonic oscillators. It used analog oscillators and filters alongside the existing electromechanical elements. Triodes are used for amplifiers and oscillators. They are also used in optical parametric oscillators and some interferometers. Parametric oscillators are used in many applications. Radio systems also use MOSFETs as oscillators, or mixers to convert frequencies. Incoherent techniques derive frequencies from a set of several stable oscillators. The lattice damage influences the frequency of crystal oscillators. The Mellotron was eventually dropped in favour of electronic oscillators and synthesizers.