A circuit for driving cold cathode tubes and external electrode
fluorescent lamps uses only 19-26 watts of power. A steady square wave
oscillator generator sets a running frequency for the circuit. A high
voltage inductor or high voltage/high frequency transformer in
combination with a current limiting capacitor, the lamp and two low
resonance value capacitors in series are set and tuned to the oscillation
frequency to achieve resonance with the oscillator. The circuit requires
an input that has been capacitively and inductively filtered to eliminate
harmonic noise in and out of the input line. A thermal shutdown feedback
circuit monitors temperature of the circuit. Further, a non-inductive or
non-capacitive loading lamp detection feedback and a lamp disconnect
driver eliminates false disconnects at start up due to cold bulbs and
allows all lamps running on the circuit to continue operation if one is
disconnected.