Discover

A 'coil' is a series of s. A 'coiled coil' is a structure where the coil itself is in turn also looping.

Contents

General applications

Electromagnetic coils

Analysis

Coil examples

Chemistry, biology and medicine

In Ceramics (Fine Arts)

External links

General applications

A ''coil'' is made up of materials, usually rigid, which can be fashioned into a spiral or 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 ''coil spring'' is the most common type of spring.

★ A set of stairs fashioned in a coil shape, which are called spiral staircases.

★ A Slinky is a ''coil-shaped'' toy.

★ ''Evaporator coils'' are used in air conditioning and other refrigeration cycles.

★ A ''boiler coil'' is an element in a water heater.

★ A ''Alpine coil'', one of several coil knots, is a method for carrying a rope.

★ Quilling coils use shaped paper to create artisitic designs.

Electromagnetic coils

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 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



where ''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 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:

$,\; Inductance^\{microhenries\}\; =\; (radius^2$
★ number of turns^2)/(9
★ radius + 10
★ length)

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 $,\; r\; =\; c\; /2\; pi$, with ''r'' as the radius, ''c'' as the circumference, and π (the Greek letter pi) as the constant 3.141. The circumference of a coil can be calculated by $c\; =\; pi\; cdot\; d$, with ''d'' as the diameter of the coil and π as 3.141.

Coil examples

Some common electromagnetic coils include:

★ A ''bifilar coil'' is a coil that employs two 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 coil'' is used in the process of removing permanent magnetism (magnetic hysteresis) from an object.

★ A ''choke coil'' (or ''choking coil'') is low-resistance inductor used to block alternating current while passing direct current.

★ A ''Garrett coil'' is used in metal detectors.

★ 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 ''Oudin coil'' is a disruptive discharge coil.

★ The ''polyphase coils'' 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 converts energy into linear motion.

★ 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, "''Producing wound components''". Surrey.ac.uk, 2005 October 9.

Chemistry, biology and medicine

A 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 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.

★ The ''DNA coil'' is a nucleic acid structure that contains the genetic instructions specifying the biological development of all cellular forms of life (and many viruses).

★ A ''random coil'' is a polymer conformation where the monomers are arranged at random.

★ The ''RNA coil'' is a nucleic acid structure consisting of a string of covalently-bound nucleotides.
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 technqiues, it may prove very diffcult 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 in 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

★ For the definition of and words related to it, see Wiktionary.