Fluorescent tubes power supply - has thyristor controlling oscillation through series LC circuit with no transistors

摘要

An A.C. supply is derived from a D.C. source and is used for fluorescent tubes, particularly those employed in railway carriages. The circuit is transistorless obviating the problems associated with a varying D.C. input and tube condition and the consequent damage to circuits including transistors. The oscillator section of the power supply consists basically of a series LC circuit controlled by a Thyristor (2), all three elements are in series across the D.C. supply (+, -). Gating of the thyristor and the consequent output to the tube via a transformer (3) is derived from a pulse generator (1) providing one pulse per cycle, the duration of the sinusoidal waveform is dependant on the D.C. power level as compared with a reference source.