| 摘要 |
PURPOSE:To spoil an operation of a transistor when a running speed of an engine stands over a certain level and prevent an overrunning by providing a time constant circuit for a thyristor which is turned on by applying a positive voltage of an AC generator to turn the transistor on. CONSTITUTION:A time constant circuit 8 which holds for a certain period an on condition of a thyristor (SCR)4 after activated is connected between a gate and a cathode of the SCR4 in a transistor ignition device having no signal coil. When a running speed of an engine rises over a certain level, a charging voltage of a capacitor 10 in the time constant circuit is reduced. As a positive voltage from an AC generator 1 is raised before the SCR4 is biased off, on the condition of the SCR4 is held until the positive voltage is approximately zero. During the on condition, a Tr3 does not execute an ignition behavior. Thereby, an overrunning may be prevented without providing an overrunning preventive thyristor. |
