This inverter is very easy to construct, reliable, and even powerful enough to light up a 15W florescent tube if you cool your transistor well.The only hard to find piece of this baby is the so called yellow inverter transformer.
It is a miniature high frequency transformer that has a 25mm lenth 20mm breth 5mm width ferrite core, 30 turns of primary, 15 turns of feedback, and 250 turns of secondary all concentric, wound on plastic frame than wrapped with a yellow adhesive tape.
Use AWG28 (~0.3mm) wire to form primary and feedback windings and AWG32 (0.2mm) wire to form secondary. Make out a smooth winding for maximum performance and easy fitting. Place primary and feedback windings on opposite sides of the frame. Primary winding will run over on feedback in this case but it is not so important. It also isn’t important in which direction the windings are made, you just have to change two wires’ places to make circuit work, But for a problemless first run and make the transformer to fit on the PCB right, follow these instructions
Number the four slot as 1-2-3-4. Now take the care: start with winding the feedback, put wire at slot 2 then wind on clockwise. When 18 cycles completed, stop winding and put the end of the wire in slot 3. Start on slot 4 for primary, wind 25-30 cycles clockwise and end in slot 1. Now the polarity of the leads are correct for the layout of the printed circuit board design. If you make a mistake at this point or just confused, it does not matter at all. Allow wires came out 2cm or more long from the frame, then you will be able to swap feedback (or primary) connections in case of wrong phase polarity. There should be thin spacers made out of adhesive tapes, between the contact points of core parts. If you got your ferrite core with this spacers on it, do not remove them. If there isn’t any spacers, you can use very thin adhesive tape to make them. If you don’t use any, performance of the transformer will be degraded. You should manually move two core parts relative to each other in order to find the best operating point which can be determined from the brightness of the lamp
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