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Flyback transformer winding for uc3842

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nishu's

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am a confused with dot notation of transformer design in datasheet. Please refer to attached diagram and suggest if its right to wound accordingly.
 

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nishu's

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Can you mention in following image which nodes on Design should be attached to what pins of bobbin if we look bobbin from top, I have marked bobbin.
which pin from should i start for particular winding and what direction (clockwise or counter-clockwise) if i look from top.

http://obrazki.elektroda.pl/5254386600_1433923649.png

regards
nishu
 

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There is no real way of knowing, because there is no standard method of numbering pins on transformers.

If its to fit on an existing circuit board, you will need to trace all the tracks and work out what each pin does.
If its something you are building up as part of a from scratch project, you can use any pins you like.
That is the problem, there is no standard method for doing this.
 

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I was building a flyback myself using uc3842, transfortransforme didnt seem wdidntto work. My best is because of mismatched start and end flyback inductor isnt storing any energy. As after kickoff from supply derived from resistor through input rail, mosfet turns on and aux doesnt seem to produce anything, same goes for output.
 

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There should still be some voltage on both the aux and the output windings, even if they are both connected the wrong way around.
The forward voltage swings one polarity, flyback the other polarity.
So something is very wrong.

Only reason I can think of, is the transformer may be designed for a much higher switching frequency than you were using.
 

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