Ballast power control circuit

A ballast circuit for energizing a lamp, comprising:

• first and second input terminals for receiving an AC input signal which energizes the ballast circuit;
• an inductive element coupled to the first input terminal;
• a capacitive element coupled in parallel with the lamp, the capacitive element having a first and second terminals, said first terminal being coupled to the inductive element;
• a control circuit coupled to a switch for controlling a state of the switch;
• a plurality of switches each of which is coupled in series with a respective one of a plurality of capacitors and connected to the control circuit;
• wherein a current flowing through the capacitive element and the inductive element resonates in series.

A ballast circuit for energizing a lamp, comprising:

• first and second input terminals for receiving an AC input signal which energizes the ballast circuit;
• an inductive element coupled to the first input terminal;
• a capacitive element coupled in parallel with the lamp, the capacitive element having a first and second terminals, said first terminal being coupled to the inductive element, the capacitive element having first and second capacitors coupled end to end, and
• a switching element coupled to the first capacitor for selectively shorting the first capacitor,
• wherein a current flowing through the capacitive element and the inductive element resonates in series.

A ballast circuit for energizing a lamp, comprising:

• first and second input terminals for receiving an AC input signal which energizes the ballast circuit;
• an inductive element coupled to the first input terminal;
• a capacitive element coupled in parallel with the lamp, the capacitive element having a first and second terminals, said first terminal being coupled to the inductive element, the capacitive element including
• first and second capacitors coupled in parallel and a switching element coupled in series with the first capacitor;
• wherein a current flowing through the capacitive element and the inductive element resonates in series.

A ballast circuit for energizing a lamp, comprising:

• first and second input terminals for receiving an AC input signal which energizes the ballast circuit;
• an inductive element coupled to the first input terminal;
• a capacitive element coupled in parallel with the lamp, the capacitive element having first and second terminals, said first terminal being coupled to the inductive element,
• a transformer having a first winding coupled in series with the capacitive element,
• a control circuit coupled to the second winding of the transformer for canceling a predetermined level of flux generated by the first winding,
• wherein a current flowing through the capacitive element and the inductive element resonates in series.

A ballast circuit for energizing a lamp, comprising:

• first and second input terminals for receiving an AC input signal which energizes the ballast circuit;
• an inductive element coupled to the first input terminal;
• a capacitive element coupled in parallel with the lamp, the capacitive element having first and second terminals, said first terminal being coupled to the inductive element,
• a transformer having a first winding coupled in series with the inductive element and having a second winding, and
• inductively coupled first and second inductive detection elements which are coupled to opposite ends of the lamp.

A circuit for energizing a load, comprising:

• first and second input terminals;
• a transformer having a first winding coupled to the first input terminal and a second winding coupled to a signal generator;
• an inductive element coupled to the first winding;
• first and second inductive detection elements coupled to opposite ends of the load;
• and
• a third inductive detection element coupled to a signal detector, the third detection element being inductively coupled to the first detection element,
• wherein the signal detector detects a signal from the signal generator.