Exciter circuit

An ignition system exciter circuit comprising:

• an energy storage capacitor;
• a charging circuit for charging the capacitor;
• a discharge circuit connectable to an igniter plug;
• and a first switching circuit for controlling discharge of the capacitor through the discharge circuit and plug;
• said discharge circuit comprising a step-up transformer having a primary winding and a secondary winding;
• said secondary winding having a first terminal that is connectable to a first terminal of the igniter plug and a second terminal connectable to a second terminal of the igniter plug;
• said primary winding having a first terminal that receives energy from the capacitor by operation of the switching circuit;
• and a second switching circuit connected between said primary winding first terminal and said secondary winding first terminal.

An ignition system exciter circuit comprising:

• a storage capacitor;
• a charging circuit for charging the capacitor;
• a discharge circuit connectable to an igniter plug;
• and a first switching circuit for controlling discharge of the capacitor through the discharge circuit and plug;
• said discharge circuit comprising a step-up transformer for transforming voltage stored on the capacitor to a higher voltage across the igniter plug when the first switching circuit is closed;
• said transformer having a primary winding and a secondary winding, with said secondary winding having a first terminal that can be coupled to a first terminal of the igniter plug and a second terminal that can be coupled to a second terminal of the igniter plug;
• and a second switching circuit that is responsive to a voltage transition across the igniter plug and that prevents said transformer primary and secondary windings from conducting spark discharge current.