The ER, EC, and ETD ferrite cores are presented in a datasheet but visually I don't see any difference between them. The search results also say the same thing. enter image description here

  • 1
    \$\begingroup\$ Compare price, mean length of turn, minimum core area and total core volume for them. Also, notice the straight legs on the ER. \$\endgroup\$
    – winny
    Jun 15 at 12:26
  • \$\begingroup\$ See also the central leg gap if one. \$\endgroup\$
    – Antonio51
    Jun 15 at 14:26

1 Answer 1


EC and ETD are almost identical. ER is slightly different.

EC and ETD (ETD means economic transformer design) have both circular centre leg and circular winding window. ER's winding window is not perfect circular. Look at the outer legs closely and you'll get what I mean.

EC and ETD can generally be used interchangeably (e.g. EC34 or ETD34).


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.