An induction coil or "spark coil" (
archaically
In language, an archaism (from the grc, ἀρχαϊκός, ''archaïkós'', 'old-fashioned, antiquated', ultimately , ''archaîos'', 'from the beginning, ancient') is a word, a sense of a word, or a style of speech or writing that belongs to a hi ...
known as an inductorium or Ruhmkorff coil
after
Heinrich Rühmkorff
Heinrich Daniel Ruhmkorff (Rühmkorff) (15 January 1803 – 20 December 1877) was a German instrument maker who commercialised the induction coil (often referred to as the Ruhmkorff coil).
Ruhmkorff was born in Hanover. He changed the "ü ...
) is a type of electrical
transformer
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
used to produce high-voltage pulses from a low-voltage
direct current
Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even ...
(DC) supply.
[ p.98] To create the
flux
Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport ph ...
changes necessary to induce voltage in the secondary coil, the direct current in the primary coil is repeatedly interrupted by a vibrating mechanical
contact
Contact may refer to:
Interaction Physical interaction
* Contact (geology), a common geological feature
* Contact lens or contact, a lens placed on the eye
* Contact sport, a sport in which players make contact with other players or objects
* ...
called an
interrupter
An interrupter in electrical engineering is a device used to interrupt the flow of a steady direct current for the purpose of converting a steady current into a changing one. Frequently, the interrupter is used in conjunction with an inductor (c ...
.
Invented in 1836 by
Nicholas Callan
Father Nicholas Joseph Callan (22 December 1799 – 10 January 1864) was an Irish priest and scientist from Darver, County Louth, Ireland. He was Professor of Natural Philosophy in Maynooth College in County Kildare from 1834, and is best known ...
, with additional research by
Charles Grafton Page
Charles Grafton Page (January 25, 1812 May 5, 1868) was an American scientist who developed several electrical devices for which he obtained United States patents. He was also a physician, patent examiner, and college professor of chemistry. L ...
and others,
the induction coil was the first type of transformer. It was widely used in
x-ray machine
An X-ray machine is any machine that involves X-rays. It may consist of an X-ray generator and an X-ray detector.
Examples include:
*Machines for medical projectional radiography
*Machines for computed tomography
*Backscatter X-ray machines, used ...
s,
[ Collins, 1908, p. iii](_blank)
/ref> spark-gap radio transmitters, arc lighting and quack medical electrotherapy
Electrotherapy is the use of electrical energy as a medical treatment. In medicine, the term ''electrotherapy'' can apply to a variety of treatments, including the use of electrical devices such as deep brain stimulators for neurological dise ...
devices from the 1880s to the 1920s. Today its only common use is as the ignition coil
An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system that transforms the battery's voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. So ...
s in internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...
s and in physics education to demonstrate induction
Induction, Inducible or Inductive may refer to:
Biology and medicine
* Labor induction (birth/pregnancy)
* Induction chemotherapy, in medicine
* Induced stem cells, stem cells derived from somatic, reproductive, pluripotent or other cell t ...
.
Construction and function
An induction coil consists of two coils of insulated wire wound around a common iron core ''(M)''.[ Collins, 1908, p. 16-19](_blank)
/ref> One coil, called the ''primary winding
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's c ...
'' ''(P)'', is made from relatively few (tens or hundreds) turns of coarse wire. The other coil, the ''secondary winding
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple Electrical network, circuits. A varying current in any coil of the transformer produces a varying magnetic flux in ...
,'' ''(S)'' typically consists of up to a million turns of fine wire (up to 40 gauge).
An electric current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
is passed through the primary, creating a magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
. Because of the common core, most of the primary's magnetic field couples with the secondary winding. The primary behaves as an inductor
An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a c ...
, storing energy in the associated magnetic field. When the primary current is suddenly interrupted, the magnetic field rapidly collapses. This causes a high voltage
High voltage electricity refers to electrical potential large enough to cause injury or damage. In certain industries, ''high voltage'' refers to voltage above a certain threshold. Equipment and conductors that carry high voltage warrant spec ...
pulse to be developed across the secondary terminals through electromagnetic induction
Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk ...
. Because of the large number of turns in the secondary coil, the secondary voltage pulse is typically many thousands of volt
The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827).
Defi ...
s. This voltage is often sufficient to cause an electric spark
An electric spark is an abrupt electrical discharge that occurs when a sufficiently high electric field creates an ionized, electrically conductive channel through a normally-insulating medium, often air or other gases or gas mixtures. Michael F ...
, to jump across an air gap ''(G)'' separating the secondary's output terminals. For this reason, induction coils were called spark coils.
An induction coil is traditionally characterised by the length of spark it can produce; a '4 inch' (10 cm) induction coil could produce a 4 inch spark. Until the development of the cathode ray oscilloscope
An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...
, this was the most reliable measurement of peak voltage of such asymmetric waveforms. The relationship between spark length and voltage is linear within a wide range:
: = 110kV ; = 150kV ; = 190kV ; = 230kV
Curves supplied by a 1984 reference agree closely with those values.
Interrupter
To operate the coil continually, the DC supply current must be repeatedly connected and disconnected to create the magnetic field changes needed for induction. To do that, induction coils use a magnetically activated vibrating arm called an ''interrupter'' or ''break'' (''A'') to rapidly connect and break the current flowing into the primary coil. The interrupter is mounted on the end of the coil next to the iron core. When the power is turned on, the increasing current in the primary coil produces an increasing magnetic field, the magnetic field attracts the interrupter's iron armature (''A''). After a time, the magnetic attraction overcomes the armature's spring force, and the armature begins to move. When the armature has moved far enough, the pair of contacts (''K'') in the primary circuit open and disconnect the primary current. Disconnecting the current causes the magnetic field to collapse and create the spark. Also, the collapsed field no longer attracts the armature, so the spring force accelerates the armature toward its initial position. A short time later the contacts reconnect, and the current starts building the magnetic field again. The whole process starts over and repeats many times per second. The secondary voltage (red, left), is roughly proportional to the rate of change of primary current (blue).
Opposite potentials are induced in the secondary when the interrupter 'breaks' the circuit and 'closes' the circuit. However, the current change in the primary is much more abrupt when the interrupter 'breaks'. When the contacts close, the current builds up slowly in the primary because the supply voltage has a limited ability to force current through the coil's inductance. In contrast, when the interrupter contacts open, the current falls to zero suddenly. So the pulse of voltage induced in the secondary at 'break' is much larger than the pulse induced at 'close', it is the 'break' that generates the coil's high voltage output.
Capacitor
An arc forms at the interrupter contacts on break which has undesirable effects: the arc consumes energy stored in the magnetic field, reduces the output voltage, and damages the contacts. To prevent this, a quenching capacitor
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals.
The effect of ...
''(C)'' of 0.5 to 15 μF is connected across the primary coil to slow the rise in the voltage after a break. The capacitor and primary winding together form a tuned circuit
An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can ac ...
, so on break, a damped sinusoidal wave of current flows in the primary and likewise induces a damped wave in the secondary. As a result, the high voltage output consists of a series of damped waves ''(left)''.
Construction details
To prevent the high voltages generated in the coil from breaking down the thin insulation
Insulation may refer to:
Thermal
* Thermal insulation, use of materials to reduce rates of heat transfer
** List of insulation materials
** Building insulation, thermal insulation added to buildings for comfort and energy efficiency
*** Insulated ...
and arcing
An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (p ...
between the secondary wires, the secondary coil uses special construction so as to avoid having wires carrying large voltage differences lying next to each other. In one widely used technique, the secondary coil is wound in many thin flat pancake-shaped sections (called "pies"), connected in series
Series may refer to:
People with the name
* Caroline Series (born 1951), English mathematician, daughter of George Series
* George Series (1920–1995), English physicist
Arts, entertainment, and media
Music
* Series, the ordered sets used in ...
.
The primary coil is first wound on the iron core and insulated from the secondary with a thick paper or rubber coating. Then each secondary subcoil is connected to the coil next to it and slid onto the iron core, insulated from adjoining coils with waxed cardboard disks. The voltage developed in each subcoil isn't large enough to jump between the wires in the subcoil. Large voltages are only developed across many subcoils in series, which are too widely separated to arc over. To give the entire coil a final insulating coating, it is immersed in melted paraffin wax
Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to m ...
or rosin
Rosin (), also called colophony or Greek pitch ( la, links=no, pix graeca), is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene comp ...
; the air evacuated to ensure there are no air bubbles left inside and the paraffin allowed to solidify, so the entire coil is encased in wax.
To prevent eddy current
Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a mag ...
s, which cause energy losses, the iron core is made of a bundle of parallel iron wires, individually coated with shellac
Shellac () is a resin secreted by the female lac bug on trees in the forests of India and Thailand. It is processed and sold as dry flakes and dissolved in alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and ...
to insulate them electrically. The eddy currents, which flow in loops in the core perpendicular to the magnetic axis, are blocked by the layers of insulation. The ends of the insulated primary coil often protruded several inches from either end of the secondary coil, to prevent arcs from the secondary to the primary or the core.
Mercury and electrolytic interrupters
Although modern induction coils used for educational purposes all use the vibrating arm 'hammer' type interrupter described above, these were inadequate for powering the large induction coils used in spark-gap radio transmitters and x-ray machine
An X-ray machine is any machine that involves X-rays. It may consist of an X-ray generator and an X-ray detector.
Examples include:
*Machines for medical projectional radiography
*Machines for computed tomography
*Backscatter X-ray machines, used ...
s around the turn of the 20th century. In powerful coils the high primary current created arcs at the interrupter contacts which quickly destroyed the contacts. Also, since each "break" produces a pulse of voltage from the coil, the more breaks per second the greater the power output. Hammer interrupters were not capable of interruption rates over 200 breaks per second and the ones used on powerful coils were limited to 20 – 40 breaks per second.
Therefore much research went into improving interrupters and improved designs were used in high power coils, with the hammer interrupters only used on small coils under 8" sparks. Léon Foucault
Jean Bernard Léon Foucault (, ; ; 18 September 1819 – 11 February 1868) was a French physicist best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of Earth's rotation. He also made an early measurement ...
and others developed interrupters consisting of an oscillating needle dipping into and out of a container of mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
. The mercury was covered with a layer of spirits which extinguished the arc quickly, causing faster switching. These were often driven by a separate electromagnet or motor, which allowed the interruption rate and "dwell" time to be adjusted separately from the primary current.
The largest coils used either electrolytic or mercury turbine interrupters. The electrolytic or Wehnelt interrupter, invented by Arthur Wehnelt
Arthur Rudolph Berthold Wehnelt (April 4, 1871 – February 15, 1944) was a German physicist, noted for important contributions in the fields of X-ray physics, gas discharges and electron emission.
Life
Wehnelt's parents returned to Germany fr ...
in 1899, consisted of a short platinum
Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver".
Platinu ...
needle anode
An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...
immersed in an electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
of dilute sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...
, with the other side of the circuit connected to a lead plate cathode
A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in whi ...
. When the primary current passed through it, hydrogen gas bubbles formed on the needle which repeatedly broke the circuit. This resulted in a primary current broken randomly at rates up to 2000 breaks per second. They were preferred for powering X-ray tubes. They produced a lot of heat and due to this the hydrogen could explode. Mercury turbine interrupters had a centrifugal
Centrifugal (a key concept in rotating systems) may refer to:
*Centrifugal casting (industrial), Centrifugal casting (silversmithing), and Spin casting (centrifugal rubber mold casting), forms of centrifigual casting
*Centrifugal clutch
*Centrifug ...
pump which sprayed a stream of liquid mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
onto rotating metal contacts. They could achieve interruption rates up to 10,000 breaks per second and were the most widely used type of interrupter in commercial wireless stations.[ Page 31 describes electrolytic interrupter, but does not identify as Wehnelt interrupter.]
History
The induction coil was the first type of electrical transformer
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
. During its development between 1836 and the 1860s, mostly by trial and error, researchers discovered many of the principles that governed all transformers, such as the proportionality between turns and output voltage and the use of a "divided" iron core to reduce eddy current
Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a mag ...
losses.
Michael Faraday
Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic inducti ...
discovered the principle of induction, Faraday's induction law, in 1831 and did the first experiments with induction between coils of wire. The induction coil was invented by the American physician Charles Grafton Page
Charles Grafton Page (January 25, 1812 May 5, 1868) was an American scientist who developed several electrical devices for which he obtained United States patents. He was also a physician, patent examiner, and college professor of chemistry. L ...
in 1836
archived
and independently by Irish scientist and Catholic priest Nicholas Callan
Father Nicholas Joseph Callan (22 December 1799 – 10 January 1864) was an Irish priest and scientist from Darver, County Louth, Ireland. He was Professor of Natural Philosophy in Maynooth College in County Kildare from 1834, and is best known ...
in the same year at the St. Patrick's College, Maynooth[Callan, N. J. ''A Description of an Electromagnetic Repeater'' in and p.522 fig. 52] and improved by William Sturgeon
William Sturgeon (22 May 1783 – 4 December 1850) was an English physicist and inventor who made the first electromagnets, and invented the first practical British electric motor.
Early life
Sturgeon was born on 22 May 1783 in Whittington, ...
. George Henry Bachhoffner
George Henry Bachhoffner (13 April 1810 – 22 July 1879), was a British scientist, one of the founders of the London Polytechnic Institution, and a lecturer on scientific subjects.
Bachhoffner was a native of London. He married Caroline Derby o ...
and Sturgeon (1837) independently discovered that a "divided" iron core of iron wires reduced power losses.[ Fleming (1896) ''The Alternate Current Transformer in Theory and Practice, Vol. 2'', p. 10-11](_blank)
/ref> The early coils had hand cranked interrupters, invented by Callan and Antoine Philibert Masson (1837).[ On page 458, an interrupter consisting of a toothed wheel is described.][ On page 134, Masson describes the toothed wheels that functioned as an interrupter.] The automatic 'hammer' interrupter was invented by Rev. Prof. James William MacGauley
James William MacGauley (c.1806–1867) was an Irish Catholic priest, physicist, and inventor.
Life
MacGauley was born around 1806 into a Catholic family at Kilmainham, Dublin, where his father Benjamin was a carpenter. After school in Dublin, he ...
(1838) of Dublin, Ireland,[ presented at meeting of September 1837 in Liverpool, England] Johann Philipp Wagner (1839), and Christian Ernst Neeff (1847).[ Description of Neeff and Wagner's earlier toothed wheel interrupter] Hippolyte Fizeau
Armand Hippolyte Louis Fizeau FRS FRSE MIF (; 23 September 181918 September 1896) was a French physicist, best known for measuring the speed of light in the namesake Fizeau experiment.
Biography
Fizeau was born in Paris to Louis and Beatrice Fiz ...
(1853) introduced the use of the quenching capacitor. Heinrich Ruhmkorff
Heinrich Daniel Ruhmkorff (Rühmkorff) (15 January 1803 – 20 December 1877) was a German instrument maker who commercialised the induction coil (often referred to as the Ruhmkorff coil).
Ruhmkorff was born in Hanover. He changed the "ü" ...
generated higher voltages by greatly increasing the length of the secondary, in some coils using 5 or 6 miles (10 km) of wire and produced sparks up to 16 inches. In the early 1850s, American inventor Edward Samuel Ritchie
Edward Samuel Ritchie (1814–1895), an American inventor and physicist, is considered to be the most innovative instrument maker in nineteenth-century America, making important contributions to both science and navigation.
Early life and career
R ...
introduced the divided secondary construction to improve insulation. Jonathan Nash Hearder
Jonathan Nash Hearder (24 December 1809 – 16 July 1876) was a British electrical engineer, inventor, and educator. He is best known for his work in developing alternative experimental procedures for use by the blind and vision impaired, and f ...
worked on induction coils. Callan's induction coil was named an IEEE Milestone in 2006.
Induction coils were used to provide high voltage for early gas discharge Electric discharge in gases occurs when electric current flows through a gaseous medium due to ionization of the gas. Depending on several factors, the discharge may radiate visible light. The properties of electric discharges in gases are studied ...
and Crookes tube
A Crookes tube (also Crookes–Hittorf tube) is an early experimental electrical discharge tube, with partial vacuum, invented by English physicist William Crookes and others around 1869-1875, in which cathode rays, streams of electrons, were dis ...
s and other high voltage research. They were also used to provide entertainment (lighting Geissler tube
A Geissler tube is an early gas discharge tube used to demonstrate the principles of electrical glow discharge, similar to modern neon lighting. The tube was invented by the German physicist and glassblower Heinrich Geissler in 1857. It consist ...
s, for example) and to drive small "shocking coils", Tesla coil
A Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in 1891. It is used to produce high-voltage, low-current, high-frequency alternating-current electricity. Tesla experimented with a number of different ...
s and violet ray
A violet ray is an antique medical appliance used during the early 20th century to discharge in electrotherapy. Their construction usually featured a disruptive discharge coil with an interrupter to apply a high voltage, high frequency, low cur ...
devices used in quack medicine
Quackery, often synonymous with health fraud, is the promotion of fraudulent or ignorant medical practices. A quack is a "fraudulent or ignorant pretender to medical skill" or "a person who pretends, professionally or publicly, to have skill, k ...
. They were used by Hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that on ...
to demonstrate the existence of electromagnetic waves, as predicted by James Clerk Maxwell
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and ligh ...
and by Lodge
Lodge is originally a term for a relatively small building, often associated with a larger one.
Lodge or The Lodge may refer to:
Buildings and structures Specific
* The Lodge (Australia), the official Canberra residence of the Prime Ministe ...
and Marconi in the first research into radio waves. Their largest industrial use was probably in early wireless telegraphy
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimental technologies for ...
spark-gap radio transmitters and to power early cold cathode
A cold cathode is a cathode that is not electrically heated by a filament.A negatively charged electrode emits electrons or is the positively charged terminal. For more, see field emission. A cathode may be considered "cold" if it emits more el ...
x-ray tube
An X-ray tube is a vacuum tube that converts electrical input power into X-rays. The availability of this controllable source of X-rays created the field of radiography, the imaging of partly opaque objects with penetrating radiation. In contrast ...
s from the 1890s to the 1920s, after which they were supplanted in both these applications by AC transformer
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
s and vacuum tube
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied.
The type kn ...
s. However their largest use was as the ignition coil
An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system that transforms the battery's voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. So ...
or spark coil in the ignition system
An ignition system generates a spark or heats an electrode to a high temperature to ignite a fuel-air mixture in spark ignition internal combustion engines, oil-fired and gas-fired boilers, rocket engines, etc. The widest application for spark ig ...
of internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...
s, where they are still used, although the interrupter contacts are now replaced by solid state switches. A smaller version is used to trigger the flash tube
Flash, flashes, or FLASH may refer to:
Arts, entertainment, and media
Fictional aliases
* Flash (DC Comics character), several DC Comics superheroes with super speed:
** Flash (Barry Allen)
** Flash (Jay Garrick)
** Wally West, the first Kid F ...
s used in cameras and strobe
A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope. The word originated from the Ancient Greek ('), meaning ...
lights.
See also
* Ignition coil
An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system that transforms the battery's voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. So ...
* Trembler coil
A trembler coil, buzz coil or vibrator coil is a type of high-voltage ignition coil used in the ignition system of early automobiles, most notably the Benz Patent-Motorwagen and the Ford Model T. Its distinguishing feature is a vibrating magnetica ...
* Spark gap transmitter
A spark-gap transmitter is an obsolete type of radio transmitter which generates radio waves by means of an electric spark."Radio Transmitters, Early" in Spark-gap transmitters were the first type of radio transmitter, and were the main type use ...
* Transformer
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
* Tesla coil
A Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in 1891. It is used to produce high-voltage, low-current, high-frequency alternating-current electricity. Tesla experimented with a number of different ...
* Faraday's law of induction
Faraday's law of induction (briefly, Faraday's law) is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (emf)—a phenomenon known as electromagnetic inducti ...
* Ignition system
An ignition system generates a spark or heats an electrode to a high temperature to ignite a fuel-air mixture in spark ignition internal combustion engines, oil-fired and gas-fired boilers, rocket engines, etc. The widest application for spark ig ...
* Inductor
An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a c ...
* Magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
* Nicholas Callan
Father Nicholas Joseph Callan (22 December 1799 – 10 January 1864) was an Irish priest and scientist from Darver, County Louth, Ireland. He was Professor of Natural Philosophy in Maynooth College in County Kildare from 1834, and is best known ...
Footnotes
Further reading
* Norrie, H. S., "''Induction Coils: How to Make, Use, and Repair Them''". Norman H. Schneider, 1907, New York. 4th edition.
*
* Has detailed history of invention of induction coil
External links
*
Battery powered Driver circuit for Induction Coils
*
*
Relay Technical Information
See section "Contact Protection – Counter EMF".
Capacitive Discharge Ignition vs Magnetic Discharge Ignition: Ignition System Options for the TR4A
See figure 9 for actual discharge.
{{DEFAULTSORT:Induction Coil
Electric transformers
Electrical breakdown