etd39 ferrite core
https://www.storeboard.com/blogs/general/4-dirty-little-secrets-about-the-ferrite-core-usb-cable-industry/2449862
Within an AC software, the single-core ferrite is helpful being a voltage doubler. It's also beneficial in lots of other sorts of apps and may be used in a wide range of purposes. Only one-core ferrite can be utilized