| 摘要 |
The invention relates to a low voltage, high frequency driver circuit for a fluorescent tube which has high efficiency and low heat output, the invention provides a fluorescent tube driver having first positive and second nominally zero input terminals arranged to be supplied by a low voltage dc source comprising an oscillator circuit consisting of a current source effectively connected through a first capacitor to the second input, a transformer having first and second windings and a transistor, the base of the transistor being connected through the first winding to the junction of the current source and the first capacitor, the collector of the transistor being connected through the second winding to the first input and the emitter of the transistor being connected to the second input, the current source being adjustable such that the power output is in the range 18 to 40 watts, and output means comprising a third winding on the transformer, the third winding having a greater number of turns than the first and second windings and connection points on the third winding for connection to a fluorescent tube, in which the value of the first capacitor is selected so that the frequency of oscillation is in the range 45 to 100 KHz and the transformer and current supply are arranged such that the oscillator operates in switched mode. The second and first windings of the transformer have a ratio of 1.8 to 2.2:1 (preferably 2:1) and the transformer has a ferous material core.
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