JPS6160267B

Changes in the magnetic field around a Wiegand wire created by a magnetic rotor coupled to a shaft of the engine induce a signal in a sensing coil. The signal is applied to an input switch which forms part of a control circuit. The output of the control circuit is connected to an interrupter switch connected in series with an ignition coil such that a spark is created at the secondary of the ignition coil when the interrupter switch opens. The control circuit maintains the interrupter switch in the nonconductive state for a predetermined percentage of the ignition cycle at low engine speeds and for a lesser percentage at high engine speeds so that enough energy can build in the ignition coil prior to the next interruption at the higher speeds.