| 摘要 |
A starter circuit of the half-wave (rectifying) type has terminals (X,Y) connected between the cathodes of a fluorescent tube (T) which are in turn connected in series with a ballast inductor L to the mains supply. The starter circuit includes a Fluoractor device (F) which is controllably triggered to operate in a first phase providing heater current for the cathodes and in a subsequent phase to generate high voltage ignition pulses with the aid of the inductor L. The gate circuit of the Fluoractor device (F) is shunted by a bipolar or field effect transistor (TR2, TR1) to divert current entirely from the Fluoractor if the fluorescent tube (T) fails to strike after a certain period. A timing circuit including two capacitors (C3, C4) in a charge pump arrangement is connected through a diode (D5) between terminals (X,Y) to charge one of the capacitors (C4) in the supply half-cycles of opposite polarity to those to which the Fluoractor (F) responds. Charge increments are transferred to the other capacitor (C3) building up a bias voltage applied to the transistor (TR2, TR1) to turn it on and cause the starter circuit to enter first a pulsing mode and then a quiescent mode. <IMAGE>
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