transformer primary/secondary identification (oep1200)

crutschow said:

For a 1:1 transformer, the input and output are interchangeable.

In general, transformers do not have a direction of signal flow. Any winding can be used as an input. For example, if you apply 12VAC to the 12V winding of a 120VAC to 12VAC transformer, you will get 120VAC at the 120V winding.

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MikeMl said:

According to this data sheet, the primary and secondary have a slightly different DC resistance. Makes it easy to use an Ohmmeter to tell which is which

Note that this transformer will tolerate only a small DC current in the primary; likely primary and secondary are wound with different size wire, hence the slight difference in resistance.

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