Hi Paul
I almost can figure it out by using the tutorial below recommended by a good guy
http://www.coilcraft.com/pdf/doc157.pdfBut then please see 3rd page on the 1st and 3rd and 4th equation after figure 5.
I can see that 1st and 3rd equations are contradicting.
Then for the initial Zs' question, I can use 4th equation to understand it.
However as for how to get 4th equation, I try to solve from the 1st equation(after Figure 5), then I find the other way round for the result.
It is V1/I1 = V2/I2. [(a+1)^2]
So which one is right?
Anyone please help
rgds and thanks
Jason