Abstract: By means of an auxiliary voltage the semi-conductor controlled rectifier of a capacitor discharge magneto ignition system is at some limiting speed of the engine kept in its conducting condition from a time before the initiation of a charging halfwave until at least after the end of the charging halfwave. The auxiliary voltage is derived from a halfwave of polarity opposite to that which charges the ignition capacitor, and acts through a transistor to keep the SCR continuously conducting while the overspeed condition continues. The overspeed limit will be determined by the bias applied to the transistor.

Abstract: To prevent spurious responses of a semiconductor switching element used in triggered magneto-type semiconductor ignition-switching systems, primarily due to noise signals introduced by the magneto, the control circuit for the ignition system includes a common, parallel connected R/C compensation circuit, connected through decoupling diodes to the ignition trigger pulse sources for the respective cylinders and the grounded main terminal of the switching element to supply a compensating voltage which suppresses noise voltages which increases with increasing speed of the internal combustion engine and thus dynamically compensates for generated noise pulses.