TM 5-4240-501-14&PTHEORIES OF OPERATIONIgnitionIGNITIONA magneto in a sense consists of two simple circuits,one called a primary circuit and the other the secondarycircuit. Both circuits have windings which surround thesame iron core and the magnets in the flywheel or rotoract on both circuits. Current can be induced in each bychanging the magnetism in or around the coils of thecircuit.The primary circuit has relatively few turns of heavy wireand the circuit includes a set of breaker points and acondenser.The secondary circuit has a coil with many turns oflighter wire which are wound around the out-side of the primary winding, and includes a spark plug.There are about 60 turns in the secondary to each turn inthe primary.A permanent magnet is mounted in the flywheel or rotor.As the flywheel rotates, the magnet is brought intoproximity with the coil and core.The Briggs & Stratton new ignition magneto systemdiffers from ordinary magnetos in that the voltageproduced is tailored to the needs of the engine. See Fig.26. The magnet used in this new type is a ceramicwhich develops a very high magnetic strength in a veryshort distance. The length of this magnet is 3/8" ascompared with the Alnico magnet length of 7/8".Figure 26.1414
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