How do you determine the polarity of a secondary coil of a transformer if the coil has an even number of layers (beginning and end of the coil are in the same side)?

 

its the same as with an odd number.

 

Transformer polarity is unaffected by whether the number of layers or windings is even or odd.

To determine the polarity, you can apply a momentary low voltage pulse, such as from a battery, to the primary winding and observe the pulse polarity of the secondary.

 

Turns can also be directly on top of one another, i.e. Planar wound also.
Max

 

How do you determine the polarity of a secondary coil of a transformer if the coil has an even number of layers (beginning and end of the coil are in the same side)?

It depends on the direction of the windings compared to each other, and the location (top/bottom) of the start and ends of each coil compared to each other.

Personally I like Crutschow's suggestion. If the transformer is used on AC the polarity doesn't matter. And if used on DC/SMPS etc just put it in circuit and look on the 'scope.