Copper foil coil

from Wikipedia, the free encyclopedia

A copper foil coil ( English copper foil coil , CFC) is a special version of an air coil or a choke or transformer winding not enamelled copper wire consists but of thin insulated copper sheet or foil.

The advantage over conventional wire spools when used in loudspeaker crossovers of loudspeaker boxes is the considerably greater mechanical stability and thus less susceptibility to microphones and self-induced resonances . In this application, it is usually wound onto a plastic or wooden core. When used for high frequency and in switched-mode power supplies , the better cross-sectional utilization of the conductor with foil conductors due to the skin effect also plays a role. The disadvantage is the greater self-capacitance of such coils and (depending on the structure) the more pronounced proximity effect . Another disadvantage of foil windings is the higher manufacturing and technological effort.

Foil coils are used in loudspeaker switches, digital amplifiers, switched-mode power supplies and chokes.

Foil windings made of aluminum are sometimes used in switched-mode power supply transformers . Foil coils in loudspeaker crossovers are sometimes made of sheet silver or a silver - gold alloy. These have a lower internal resistance with the same inductivity . However, the costs are higher and the relation to the benefits is unfavorable. When used as an output filter in class D amplifiers , silver foils offer a slightly lower output resistance compared to copper coils.

Related technologies are the use of flat wire and the production of chokes and transformers using conductor tracks on multilayer circuit boards . For the latter technology there are special flat designs of ferrite cores (design ELP, from English "E" low profile ), which are inserted in or through cutouts in the circuit boards.

literature

  • Eberhard Kallenbach, Peter Quendt, Rüdiger Eick: Electromagnets. Basics - calculation - construction - application. BG Teubner Verlag, Stuttgart 1994, ISBN 3-519-06163-5 , pp. 317, 318.
  • Manfred Albach: Inductors in Power Electronics. Springer Fachmedien, Wiesbaden 2017, ISBN 978-3-658-15080-8 , pp. 37-42, 63.

Web links