Electronic ballast for a discharge lamp with current sensing

A ballast circuit for a fluorescent lamp comprising:

• said inverter circuit connected to a source of direct current;
• an inverter circuit including first and second switching transistors;
• a transformer including a primary winding, first and second secondary windings;
• said first secondary winding, 180 degrees out of phase with said second secondary winding;
• said first and second secondary windings each including a circuit connection to said first and second switching transistors respectively;
• a resonant element connected between said lamp and said inverter circuit;
• a pair of oppositely poled diodes connected in parallel;
• a pair of diodes connected in parallel with said transformer;
• said diodes operated to convert current into voltage for said transformer, causing positive, or in the alternative negative voltage to be applied across said transformer causing said transformer to detect a zero crossing of current in said primary winding;
• said zero crossing of current sensing in said primary winding operated to cause voltages in said secondaries to change, said current in said transistors is zero, whereby stresses on said switching transistors are minimized.