Coil 7425 221765120 2008-06-26T00:17:14Z Wolfkeeper 41690 Revert to revision 219948811 dated 2008-06-17 16:15:39 by Tweenk using [[:en:Wikipedia:Tools/Navigation_popups|popups]] {{otheruses}} {{redirect|Winding}} A '''coil''' is a series of [[wiktionary:loop|loop]]s. A '''coiled coil''' is a structure where the coil itself is in turn also looping. ==General applications== [[Image:Ressort de compression.jpg|thumb|180px|A helical spring.]] A ''coil'' is made up of materials, usually rigid, which can be fashioned into a [[spiral]] or [[helix|helical]] shape. Flexible materials like wire, rope, hose, cable or paper can also be coiled into empty loops, or wound around a central drum or spindle. Some common applications of coils include: * A ''[[Spring (device)|coil spring]]'' is the most common type of spring. * A spiral staircase, a [[stairway]] fashioned in a coil shape. * A [[Slinky]] is a ''coil-shaped'' toy. * ''[[Evaporator coil]]s'' are used in [[air conditioning]] and other [[refrigeration cycle]]s. * A ''[[boiler]] coil'' is an element in a [[water heater]]. * An ''[[Alpine coil]]'', one of [[list of coil knots|several coil knots]], is a method for carrying a rope. * [[Quilling]] coils use shaped paper to create artistic designs. ==Electromagnetic coils== {{Main|Electromagnetic coil}} [[Image:Transformers.png|thumb|Diagram of typical transformer configurations]] An ''electromagnetic coil'' (or simply a "coil") is formed when a conductor (usually a solid copper [[wire]]) is wound around a core or form to create an [[inductor]] or [[electromagnet]]. One loop of wire is usually referred to as a ''turn'', and a coil consists of one or more turns. For use in an [[electronic circuit]], [[electrical connection]] terminals called taps are often connected to a coil. Coils are often coated with varnish and/or wrapped with insulating tape to provide additional [[Electrical insulation|insulation]] and secure them in place. A completed coil assembly with taps etc. is often called a ''winding''. A [[transformer]] is an electromagnetic device that has a ''primary winding'' and a ''secondary winding'' that transfers energy from one electrical circuit to another by magnetic coupling without moving parts. The term ''tickler coil'' usually refers to a third coil placed in relation to a primary coil and secondary coil. A [[coil tap]] is a wiring feature found on some electrical transformers, inductors and coil pickups, all of which are sets of wire coils. The coil tap(s) are points in a wire coil where a conductive patch has been exposed (usually on a loop of wire that extends out of the main coil body). As self induction is larger for larger coil diameter the current in a thick wire tries to flow on the inside. The ideal use of copper is achieved by foils. Sometimes this means that a [[spiral]] is a better alternative. Multilayer coils have the problem of interlayer [[capacitance]], so when multiple layers are needed the shape needs to be radically changed to a short coil with many layers so that the voltage between consecutive layers is smaller (making them more spiral like). ===Analysis=== The [[inductance]] of single-layer coils can be calculated to a reasonable degree of accuracy with the simplified formula <center> <math>\mathrm{\mu H}= \frac{R^2 N^2}{9 R + 10 L}</math> </center> where [[microhenry|µH]] (microhenries) are units of inductance, ''R'' is the coil [[radius]] (measured in inches to the center of the conductor), ''N'' is the number of turns, and ''L'' is the length of the coil in inches. The online [http://www.66pacific.com/calculators/coil_calc.aspx Coil Inductance Calculator] calculates the inductance of any coil using this formula. Higher accuracy estimates of coil inductance require calculations of considerably greater complexity. A layperson's translation is: <center> <math>\, Inductance^{microhenries} = (radius^2*number of turns^2)/(9*radius + 10*length)</math> </center> In calculating the distances, one centimeter is equal to 0.393700787 inches and one inch is equal to 2.54 centimeters. The inductance formula uses inches. The relationship between the radius and the [[circumference]] of a coil is <math>\, r = c /2 \pi</math>, with ''r'' as the radius, ''c'' as the circumference, and &pi; (the Greek letter [[pi]]) as the [[mathematical constant|constant]] 3.141. The circumference of a coil can be calculated by <math> c = \pi \cdot d </math>, with ''d'' as the [[diameter]] of the coil and &pi; as 3.141. ===Coil examples=== [[Image:TeslaFlatSpiralCoil.png|right|thumb|180px|[[Nikola Tesla]]'s flat spiral coil.]] Some common electromagnetic coils include: * A ''[[bifilar coil]]'' is a coil that employs two [[Parallel (geometry)|parallel]] windings. * A ''[[Barker coil]]'' is used in low field [[NMR imaging]]. * A ''[[Balun]]'' is set of transformer coils for transmission lines. * A ''[[Braunbeck coil]]'' is used in geomagnetic research. * A ''[[Degaussing#The degaussing coil|degaussing coil]]'' is used in the process of removing [[permanent magnet]]ism (magnetic [[hysteresis]]) from an object. * A ''[[Choke (electronics)|choke coil]]'' (or ''choking coil'') is low-[[electrical resistance|resistance]] [[inductor]] used to block [[alternating current]] while passing [[direct current]]. * A '''[[Flat coil]]''' is used in thin electric motor. * A ''[[Garrett coil]]'' is used in [[metal detector]]s. * A ''[[Helmholtz coil]]'' is a device for producing a region of nearly uniform [[magnetic field]]. * A ''[[hybrid coil]]'' (or ''[[bridge transformer]]'') is a single transformer that effectively has three windings. * An ''[[induction coil]]'' (or ''[[ignition coil]]'') is an electrical device in common use as the [[ignition system]] (''ignition coil or spark coil'') of internal-combustion engines. * A ''[[loading coil]]'' is, in electronics, a coil (inductor) inserted in a circuit to increase its [[inductance]]. Archaically called ''Pupin coils''. * A ''[[multiple coil magnet]]'' is an [[electromagnet]] that has several coils of wire connected in parallel. * A ''[[Maxwell coil]]'' is a device for producing almost a constant magnetic field. *A '''[[Micro coil]]''' use in security devices. * A ''[[Oudin coil]]'' is a [[disruptive discharge]] coil. * The ''[[polyphase coil]]s'' are connected together in a polyphase system such as a generator or motor. * A ''relay coil'' is the copper winding part of a [[relay]] that produces a magnetic field that actuates the mechanism. * A ''[[Repeating coil]]'' is a voice-frequency transformer. * A ''[[Rogowski coil]]'' is an electrical device for measuring alternating current. * A ''[[single coil]]'' is a type of pickup for the [[electric guitar]]. * A ''[[solenoid]]'' is a mechanical device, based around a ''coil of wire'', that usually converts energy into linear motion, however solenoids also come in a rotary motion (normally up to a turn of 90 degrees). * A ''[[telephone]] cord'' is usually manufactured in a coiled fashion, as to allow maximum length while taking up minimum space when not in use. * A ''[[Tesla coil]]'' is category of disruptive discharge coils, usually denoting a resonant transformer that generates very high voltages at radio frequencies. * A ''[[voice coil]]'' which is mounted to the moving cone of a [[loudspeaker]]. Other applications of coils exist in the field of electromagnetic devices. A [[coilgun]] is a type of cannon that uses a series of electromagnetic coils to accelerate a magnetic shell to very high velocities. The filament of an [[incandescent light bulb]] has usually the shape of a coiled coil, in order to fit the long filament in a small space. ;Further reading * Querfurth, William, "''Coil winding; a description of coil winding procedures, winding machines and associated equipment for the electronic industry''" (2d ed.). Chicago, G. Stevens Mfg. Co., 1958. * Weymouth, F. Marten, "''Drum armatures and commutators (theory and practice) : a complete treatise on the theory and construction of drum winding, and of commutators for closed-coil armatures, together with a full résumé of some of the principal points involved in their design; and an exposition of armature reactions and sparking''". London, "The Electrician" Printing and Publishing Co., 1893. * "''Coil winding proceedings''". International Coil Winding Association. * Chandler, R. H., "''Coil coating review, 1970-76''". Braintree, R. H. Chandler Ltd, 1977. ;External articles * R. Clarke, "''[http://www.ee.surrey.ac.uk/Workshop/advice/coils/ Producing wound components]''". Surrey.ac.uk, 2005 October 9. ==Chemistry, biology and medicine== A [[Coil (chemistry)|chemistry coil]] is a tube of spiral form, used commonly to cool originating steam of the distillation and thus to condense them in liquid form. In the [[Chemistry|study of how molecules interact with each other]], there are a few specific references to ''organic coils''. During [[self-assembly]], organic elements organize to form this structural pattern. [[Molecular self-assembly]] assembles the molecules, without guidance or management from an outside source, into these shapes. Examples of these structural patterns include: * A ''[[coiled coil]]'' is a [[structural motif]] found in many proteins. * A ''[[random coil]]'' is a [[polymer]] conformation where the [[monomer]]s are arranged at [[random]]. As an acronym, ''COIL'' denotes the [[Chemical Oxygen Iodine Laser]]. In medicine, the ''[[Guglielmi Detachable Coil]]'' is a platinum coil commonly used in intracranial non-invasive surgery, for the occlusion of brain aneurysms. ==In Ceramics (Fine Arts)== Coiling has been used to shape clay into useful beautiful vessels for many of thousands of years. It ranges from Africa to Greece and from China to New Mexico. They have used this method in a variety of ways. Using the coiling technique, it is possible to build thicker or taller walled vessels, which may not have been possible using earlier methods. The technique lets you control the walls as you build them up and allows you to build on top of the walls to make the vessel look bigger and bulge outward or narrow inward with less danger of collapsing. There are many different ways you can build ceramic objects using the coiling technique. ;Coil Construction #Squeezing the clay into a coil or rolling between your hands are two different was to make coils. Using these techniques, it may prove very difficult to make a smooth preform due to the uneven pressure applied by your hands and fingers. #When rolling with your hands, use a smooth surface. By spreading your hands (to apply even pressure), gently roll the clay back and forth until you think the preform is of the right thickness. #The roll should be a little thicker than a pencil or pen. Now stack the coils on top of each other. #Now, for strength, force the clay together as hard as you can on the inside of the piece without messing the clay up. Use your fingers and scrape the top coil onto the coil underneath. #While smoothing the inside of the piece hold your other hand on the outside so you don’t damage what you have already done. #If you want a top level, gently turn your piece over and lightly tap it on a smooth surface. #Let it dry. ;Slab pottery Construction: How to build it #Large flat pieces of clay are rolled out with a rolling pin. The slabs are cut for the base and walls and are attached together. #Slabs work goes fast but lots of care must be given to make sure that the seams won’t crack, break or pull apart during the drying process. ==External links== {{wiktionarypar|coil|winding}} * For the definition of [[Wiktionary:Coil|Coil]] and words related to it, see Wiktionary. <!-- In other languages, alphabetically by language (not code) name --> <!--nihongo--> [[Category:Helices]] [[da:Spole]] [[de:Spule]] [[fr:Bobine (électricité)]] [[it:Bobina]] [[lt:Ritė]] [[ja:巻線]] [[pt:Bobina]]