Electronic speed control for capacitor discharge ignition system

Claim 1

In a capacitor discharge ignition system for an internal combustion engine having rotatable magnet means associated with engine rotation to generate electrical energy, a capacitor chargeable by said energy and selectively connected in timed relationship with engine operation to the primary winding of an ignition coil to generate an ignition pulse by the discharge of the capacitor charge through said primary winding, as a means for protecting said engine and any apparatus driven thereby against excessive high-speed operation, an electronic shut-off system comprising a silicon controlled rectifier (SCR) having anode, cathode and gate electrodes, with its anode/cathode path connected in parallel with said capacitor and the primary winding of said ignition coil to shunt the energy from the charge coil and capacitor away from said primary winding, means for generating a voltage in response to a predetermined high rotational speed of said engine, the gate of said SCR being connected to said means for generating a voltage for triggering said SCR to its conductive state and means for maintaining the SCR in its conductive state for a predetermined time sufficient to ensure complete engine cut-off, including a second capacitor and a resistor connected to provide continuing current to said anode to hold the SCR "on" for said predetermined time.