At present, a large number of low-cost domestic electronic rectifiers are circulating in the market. In order to analyze the circuit, the author purchased a 40W electronic rectifier and drew the line as follows: 
In the above figure, the mains is connected from A1 and A2, and D1-4 constitutes full-bridge rectification. C1 and C2 are connected in series and filtered. The latter two transistors and the inductor L1-3 form a half-bridge high frequency oscillator. D5-6 protects the three poles from damage. Inductors L4 and C6 form a resonant tank, and L4 acts as a choke after the lamp is ionized and turned on.
The component is selected from the resistor-capacitor transistor as shown in the figure. Inductor L1-3 is wound on a toroidal core with an outer diameter of 10 mm and an inner diameter of 6 mm and a height of 5 mm by three single-core PVC wires. L1-2 is wound around 2T and L3 is wound three times. Note that the connection of the same name is used. L4 is made of the core of EI-19. Since the author did not remove the component, the number of turns in the wire diameter is unknown. It is found in some data about 200-300T.
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