4W Fluorescent lamp driver

This is a simple 4 W fluorescent lamp driver circuit that can be operated from a 12 V supply. The first part of the circuit includes a NE555 timer IC wired as an astable multivibrator. The output pulses from the IC are amplified by the transistor Q1. The transformer steps up the collector voltage to around 1KVto drive the fluorescent lamp. Before usi
4W Fluorescent lamp driver - schematic

ng the circuit, set the R2 at full resistance and switch on the supply, now adjust R2 so that the collector current is 300mA (use a multimeter) and this is the optimum setting for the lamp. Operating the lamp in this setting will give a better life. First, the tube is being started with cold cathodes. Tube life will be shortened as the cathode coating is gradually stripped. This isn`t just a feature of this circuit, but all those cheap battery operated torches having tubes with blackened ends. Incidentally, as there is a DC component present in the tube supply because of the single ended drive to the transformer, one end of the tube will wear out before the other. Because of the low efficiency of using a mains transformer (operating outside intended frequency range and with the interleaved core laminations saturating because of the DC component), the tube will not receive full 4W of power. Besides, 300mA @ 12V is only 3. 6W. Therefore, it will not be as bright as one operated from the mains. A push pull converter, running at high frequency, using a ferrite transformer, and having filament windings to warm to cathodes is the best way to operate fluorescent tubes from low voltage DC.

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