Theory of mechanical filters was first applied to improving the mechanical parts of phonographs in the 1920s. By the 1950s, mechanical filters were being manufactured as self-contained components for applications in radio transmitters and high-end receivers. A representative selection of the wide variety of component forms and topologies for mechanical filters are presented in this article.
About Mechanical filter in brief
A mechanical filter is a signal processing filter usually used in place of an electronic filter at radio frequencies. Its purpose is the same as that of a normal electronic filter: to pass a range of signal frequencies, but to block others. The filter acts on mechanical vibrations which are the analogue of the electrical signal. The components of a mechanical filter are all directly analogous to the various elements found in electrical circuits. The theory of mechanical filters was first applied to improving the mechanical parts of phonographs in the 1920s. By the 1950s, mechanical filters were being manufactured as self-contained components for applications in radio transmitters and high-end receivers. A representative selection of the wide variety of component forms and topologies for mechanical filters are presented in this article. In addition to electromechanical systems, mechanical systems are widely widely used to aid analysis in acoustics. Any mechanical component will unavoidably possess both mass and stiffness. This translates in terms to an LC circuit, that is a circuit consisting of an inductor and capacitor, hence mechanical components are resonators and often used as such. Capacitors may be made of thin, long, long rods, on the other hand, short, short rods are made of short, acacitors. It is still possible to make a mechanical implementation by minimising the mass and compliance of individual inductors and capacitors by making them lumped together to represent inductors, long capacitors and short inductors on a short hand. This is known as a ‘short hand’ filter, and can be used in loudspeaker cabinets to filter of audio frequency response in the design of loudspeakers.
For example, it is possible to use a mechanical design to filter mechanical vibrations or sound waves directly. In the electrical application, in addition to mechanical components which correspond to their electrical counterparts, transducers are needed to convert between the mechanical and electrical domains. The mechanical counterparts of voltage and electric current in this type of analysis are, respectively, force and velocity and represent the signal waveforms. This makes it possible to apply electrical network analysis and filter design methods to mechanical filters. In reality some damping is present as well. Resistances are not present in a theoretical filter composed of ideal components and only arise in practical designs as unwanted parasitic elements. The elements of a passive linear electrical network consist of inductor, capacitors, resistors and resistors which have the properties of inductance, elastance and resistance, respectively. This has equally valid results but requires using the reciprocals of the mechanical counterparts listed above. The circuit diagrams produced using this analogy match the electrical impedance of the mechanical system seen by the electrical circuit, making it intuitive from an electrical engineering standpoint. In this article, a mechanical impedance can be defined in terms of the imaginary angular frequency, jω, which entirely follows the electrical analogy. Hence, M → C, S → 1L, D → G where G is electrical conductance, the inverse of resistance.
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This page is based on the article Mechanical filter published in Wikipedia (as of Nov. 01, 2020) and was automatically summarized using artificial intelligence.
