- magneto
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/mag nee"toh/, n., pl. magnetos. Elect.a small electric generator with an armature that rotates in a magnetic field provided by permanent magnets, as a generator supplying ignition current for certain types of internal combustion engines or a hand-operated generator for telephone signaling. Also called magnetoelectric generator, magnetogenerator.[1880-85; short for magnetoelectric generator]
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Permanent-magnet alternating generator used mainly to produce electrical current for the ignition system in various types of internal-combustion engines, such as aircraft, marine, tractor, and motorcycle engines.The main parts of a magneto are a permanent-magnet rotor, a primary winding of a small number of turns of coarse wire, a secondary winding with a large number of turns of fine wire, a cam-type circuit breaker, and a capacitor. As the rotor turns, it produces a current in the primary winding, charging the capacitor. The cam breaks the circuit, and the magnetic field around the primary winding collapses. The capacitor releases its stored current into the primary winding, causing a reversed magnetic field. The collapse and reversal of the magnetic field produce a current in the secondary winding that is sent to the spark plugs.* * *
permanent-magnet generator mainly employed for ignition (ignition system) of compressed gasses in internal combustion engines (internal-combustion engine). Primary applications have been in small aircraft, marine, tractor, and motorcycle engines, which may not have an available battery supply. The major parts of the magneto are a permanent-magnet rotor, an armature with a primary winding containing a small number of turns, a parallel-connected capacitor, a secondary winding with a large number of turns, and a cam-type circuit breaker. As the magnetic rotor is turned, it induces a current in the primary winding. The cam breaks the circuit when the induced current is near its peak. The rapid change of magnetic field causes a high voltage to be induced in the secondary winding. This is distributed to the spark plugs for ignition.* * *
Universalium. 2010.
