Overrun prevention ignition system with ignition angle retardation circuit

An overrun prevention ignition system in which a main capacitor is charged by one component of an electromotive force of a magneto and the charge stored in said main capacitor is discharged through a primary winding of an ignition coil by triggering a main thyristor to induce a high voltage necessary to ignite an engine in a secondary winding of said ignition coil, said overrun prevention ignition system comprising;

• (a) a signal generating coil for generating an ignition signal to trigger said main thyristor, in synchronism with the rotation of said engine, said signal generating coil sharing a magneto rotor with said magneto,
• (b) a switching circuit connected to a gate circuit of said main thyristor and having a switching transistor for preventing said ignition signal from being applied to the gate of said main thyristor during a conduction period of said switching transistor,
• (c) a switching transistor control circuit connected in parallel with a series circuit of said main capacitor and said primary winding of said ignition coil to form a discharging circuit for an auxiliary capacitor to be charged in parallel with said main capacitor by said one component of the electromotive force generated in a generator coil of said magneto, said discharging circuit including a first thyristor and a resistor connected in series therewith, one end of said resistor being connected to a base terminal of said switching transistor, said switching transistor control circuit producing a switching signal to render said switching transistor conductive for a predetermined discharging period of said auxiliary capacitor, and
• (d) a circuit for producing a supplementary ignition signal continuing for a predetermined time period following to said ignition signal from said signal generating coil in response to said ignition signal, an output terminal of said supplementary ignition signal producing circuit being connected to a collector-emitter circuit of said switching transistor and to a gate-cathode circuit of said main thyristor, said supplementary ignition signal being bypassed through said switching transistor during the conduction period of said switching transistor and supplied to the gate-cathode circuit of said main thyristor after the termination of said conduction period.