| 摘要 |
An improved ignition circuit for internal combustion engines is described herein, in which a diode is connected in parallel to a primary winding of an ignition coil of a magneto, and a composite transistor circuit consisting of two transistors whose forward direction is directed in the reverse direction of said diode, is connected across said primary winding at its collector and emitter, whereby overheating of said transistors caused by a primary reverse current of said magneto ignition coil flowing into the transistors can be prevented and also proper ignition timing can be maintained. In addition, in the improved ignition circuit a series circuit of a temperature compensating resistor and a resistor is connected between the base of said composite transistor circuit and one terminal of said primary winding, an anode-cathode path of a thyristor-equivalent circuit in which a collector of a PNP transistor is connected to a base of an NPN transistor and the base of said PNP transistor is connected to the collector of said NPN transistor, is connected between the junction of said temperature compensating resistor and said resistor and the other terminal of said primary winding, and the gate of said thyristor-equivalent circuit is connected to the base of said composite transistor circuit, whereby a primary forward current through said primary winding can be steeply cut off to provide a spark discharge at an especially high voltage.
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