| 摘要 |
A speed limiting system particularly suited for use with magneto ignition systems for small internal combustion engines is disclosed. In a first embodiment, shorting transistor (38) is made conductive for a predetermined time after a first trigger pulse from a trigger coil (12) thus preventing subsequent trigger pulses from being effective above a predetermined engine speed. A capacitor (44) is charged by a trigger pulse, and maintains shorting transistor (38) conductive until it is discharged through the shorting transistor (38), subsequent trigger pulses arriving while shorting transistor (38) is conductive recharging the capacitor (44). A diode (42), which also serves to prevent the capacitor (44) from discharging through the trigger coil (12), provides for normal ignition system operation by delaying operating of the shorting transistor (38) until a trigger pulse has become effective upon the gate (34) of a SCR (30). In a second embodiment, the invention is applied to a capacitive discharge ignition system, and in a third embodiment, the invention is applied to an internally triggered ignition system.
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