"J. B. Wood"
John Popelish

In addition to the filter and secondary current comments:
If you don't load the two outputs equally, there will be Dc in the
transformer core, causing it to saturate at the end of alternating
half cycles. It will hum and get hot.


Hello, and direct current in the core as a result of current flow in the
secondary windings?


** Of course not.

Always exclude the impossible when interpreting someone's language.

In this case "DC" is an abbreviation of "DC offset " = magnetic field
offset.



If you mean eddy currents they would be AC and a
power transformer core is laminated to minimize this effect.


** WRONG.

The heat is generated by simple I squared R loss in the copper wire due to
excess primary current as a result of core saturation.

The audible hum is the iron core protesting about being driven into
saturation 50 or 60 times per second.


Either I misconstrued your comment


** You did.

or I must have been sleeping in my EE101
electric machinery course years ago.


** Maybe you were - but the behaviour of a transformer subjected to an
asymmetrical current load is rarely mentioned in elementary texts.



John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337



** Hmmmm - sounds kinda serious like ......



........ Phil