| 摘要 |
PURPOSE:To obtain the stable ignition timing and prevent the erroneous operation by providing a condenser charged by the front half cycle of a signal coil in zero cross ignition. CONSTITUTION:When a magnet generator starts revolution, a constant voltage power source circuit 9 generates a constant voltage by receiving the output of a power source spark coil 1, and the voltage in the negative direction which is generated in a signal coil 16 is added, and a transistor 24 is set into OFF- state, and a condenser 29 is charged. Further, at the transition point from negative to positive of the signal coil 16, i.e., when the revolution advances to the zero cross point, the output of a voltage comparator 21 changes to that at high level, and a transistor 40 is set into ON-state through a resistor 41, and the engine is ignited, keeping the ignition timing nearly constant. When the condenser 29 completes the electric discharge through the transistor 40 and a thyristor 4, the terminal voltage becomes zero, and during this time, no voltage is applied onto the gate of the thyristor 4, even if the transistor 40 is set into ON-state, and the erroneous ignition by noise can be prevented.
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