Abstract: A circuit arrangement which permits interfacing logic systems operating on different logic levels and thus requiring different supply voltages in which the supply voltage for the logic system having the smaller signal excursion is obtained by means of a pair of zener diodes connected in series across the potential and reference potential of the logic system having a larger signal excursion to develop a potential and reference potential for the system having smaller signal excursions lying between the respective potential and reference potential levels of the system having larger excursions.

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: An additional diode is provided in series with the charging diode through which the storage capacitor of a magneto ignition system is charged and the shutdown switch for the engine is connected between the common connection of the two diodes and the common connection of the magneto generator, and the capacitor diodes, because of their high back resistance, prevent any high positive or negative voltages from appearing across an open shutdown switch.

Abstract: In an ignition system in which the spark coil is wound right on the magneto armature and the spark is produced by electronic interruption of a short circuit across the primary winding, the first of a succession of rectified half waves applied to the electronic circuit unit has its amplitude reduced either by insertion of a circuit component in one half wave path of the rectifier to provide damping, or by the configuration of the armature core, or both. The magneto rotor has a U-shaped permanent magnet, the pole faces on the end of the legs of which are rotated past opposed pole faces of the armature core, which has the desired effect if the latter is of asymmetric U-shape or of symmetrical E-shape.

Abstract: A drive circuit for a main contactor which opens the contactor when a voltage dip occurs and if the voltage dip is of short duration closes the contactor again but blocks reclosing if the voltage dip persists. The circuit includes means to form an undervoltage pulse which has a duration which is equal to the length of time an undervoltage is present or a predetermined maximum time which ever is shorter. As long as the undervoltage pulse is shorter than the predetermined maximum the contactor is again closed but should the undervoltage persists beyond the predetermined maximum pulse length the drive circuit is allowed to become permanently disabled until further action is taken.