Bifilar coil
electromagnetic coil containing two closely spaced parallel windings
A bifilar coil is an electromagnetic coil that contains two closely spaced, parallel windings. In electrical engineering, the word bifilar describes wire which is made of two filaments or strands. It is commonly used to denote special types of winding wire for transformers. Wire can be purchased in bifilar form, usually as different colored enameled wire bonded together. For three strands, the term trifilar coil is used.
Description and applications
The parallel-wound, series connected bifilar coil is how Nikola Tesla patented (512340) it. This way the capacity between the parallel windings is charged by the increased voltage difference (1/2 of the supply voltage) between the series connected windings. This makes it possible for the coil to hold a greatly increased amount of energy in its electric field, and lowers the resonant frequency of the coil drastically.
Some bifilars have adjacent coils in which the convolutions are arranged so that the potential difference is magnified (i.e., the current flows in same parallel direction). Others are wound so that the current flows in opposite directions.
The public source identifies “Bifilar coil” as electromagnetic coil containing two closely spaced parallel windings. This brief keeps that definition visible, then builds a research path around Bifilar, coil and electromagnetic.
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This entry incorporates text from “Bifilar coil” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.