Magneto (electrical)

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A magneto is an electrical generator that uses permanent magnets to produce alternating current. Hand-cranked magneto generators were used to provide ringing current in early telephone systems. Magnetos adapted to produce pulses of high voltage are used in the ignition systems of some gasoline-powered internal combustion engines to provide power to the spark plugs.^[1] The magneto is now confined mainly to engines where there is no available electrical supply, for example in lawnmowers and chainsaws. It is also universally used in aviation piston engines even though an electrical supply is usually available. This is because a magneto ignition system is more reliable than a battery-coil system. People discussing magnetos and coils used in early internal-combustion engines generally used the term "tension" instead of the more modern term "voltage."

• 1 History
• 2 Operation
• 3 Aviation
• 4 Automobile
• 5 Telephone
• 6 See also
• 7 Notes

History

Production of electric current from a moving magnetic field was demonstrated by Faraday in 1831. The first machines to produce electric current from magnetism used permanent magnets; the dynamo machine, which used an electromagnet to produce the magnetic field, was developed later. The machine build by Hippolyte Pixii in 1832 used a rotating permanent magnet to induce alternating voltage in two fixed coils.^[2]

The first person to develop the idea of a high-tension magneto was Andre Boudeville, but his design omitted a condenser (capacitor); Frederick Richard Simms in partnership with Robert Bosch were the first to develop a practical high-tension magneto.^[3]

Magneto ignition was introduced on the 1899 Daimler Phönix. This was followed by Benz, Mors, Turcat-Mery, and Nesseldorf,^[4] and soon was used on most cars up until about 1918 in both low voltage (voltage for secondary coils to fire the spark plugs) and high voltage magnetos (to fire the spark plug directly, similar to coil ignitions, introduced by Bosch in 1903).^[4]

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