Fluorescent lamp electronic ballast circuit 10

(10) Fluorescent lamp electronic ballast circuit 10
    The circuit is shown in Figure 2-20. This circuit adopts the form of high-frequency self-excited triggering and
consists of capacitors C4, C5 and negative temperature coefficient thermistor PTC to form a "soft start" circuit, which allows the filament to be properly heated before emitting electrons to extend the life of the lamp.
The lamp can only be started when the PTC thermistor suddenly reaches a high resistance level.
    The circuit uses the MJE13005 tube, a special device for electronic ballasts (VTi, VT2 in the picture). Its collector withstand voltage is ≥
400V, the breakdown performance is steep, the saturation voltage drop is small, and the switching speed is fast, p= 20~30.
    Resistor Ri, capacitor Cl and inductor L form an anti-interference circuit to suppress external interference from the ballast and lamp and extend
the life of the ballast and lamp.