An energy conversion device employing an oscillating resonant converter producing oscillations, having DC input terminals producing a control signal and adapted to power at least one gas discharge lamp having heatable filaments, the device comprising: voltage source means providing a constant or variable magnitude DC voltage between the DC input terminals; output terminals connected to the filaments of the gas discharge lamp; control means capable of receiving control signals from the DC input terminals and from the resonant converter, and operable to effectively initiate the oscillations, and to effectively stop the oscillations of the converter; and direct current blocking means coupled to the output terminals and operable to stop flow of the control signal from the DC input terminals, whenever at least one gas discharge lamp is removed from the output terminals or is defective. view more

The device according to claim 1 wherein the resonant converter comprises a capacitor and an inductor connected in series via an intermediate node.

The device according to claim 1 wherein the direct current blocking means includes a capacitor and is connected effectively across at least one heatable filament of at least one gas discharge lamp.