[SOLVED] SMPS Transformer Construction related issues

[papaisou11]

Hi...

I am making a power supply but stuck at transformer construction related issues. I already generated the schematic and Transformer construction parameters from PI Expert tool.
I am planning to make the transformer by hand at my home for my prototype. But few things are not cleared.

I am attaching the transformer construction guide. Please Find the attachment.

View attachment Transformer_Construction.pdf

My questions are:-

1. How to follow Winding direction? here showing clockwise, does this means rotating the wire clockwise or rotating the bobbin?

2. If I hold the bobbin as primary pins on my left, Should I change the orientation while winding the secondary side?

3. Primary winding will go from Left to Right, What about the Secondary winding, will it go from right to left without changing the bobbin orientation? My Bobbin is a Horizontal one.

4. How to check after making it? I have LCR meter, O-scope, DC power supply and function generator.
It's Showing Leakage Inductance of 8.56uH when all other pins are shorted, Is this means that all other windings except primary winding are shorted with a single wire at a single point or the 2 pins of bias winding shorted, 2 pins of secondary winding shorted(no shorted connection between bias short and secondary short)?

It will be a great help if someone provide step by step winding procedure with the information of orientation of bobbin.

Thanks and Regards,
SaV

 

[treez]

Use the right hand screw rule to find which way the current will put the field in the core.....remmember in a flyback, both pri and sec, when conducting, will put the field in the same direction as each other.......just it dies down in the sec, and of course bbuilds up in the pri.

For flyback If you "right hand screw" it in pri and sec after youve wound it, and the field direction is opposite for pri and sec, then you have done it wrong.

- - - Updated - - -

if you have say 1:1 pri and sec, and you connect them in series in such a way that current goes through both of them, but puts the fields in opposite directions in each, then you will see zero inductance with an LCR meter...this is the basis of how you know if youve wound it right after youve wound it....the polarity.
Think of the field direction in the core rather than clkwise/anticlkwise.