All they had to do was not spin the story as if this guy figured out something that tesla didnt. There are ample explanations in the comments above. It is a really cool diy project though, and i wish they had written about it as such.

On an unrelated note, i think that whenever a commenter reffers to other comments in general, they should always say "the comments above" instead of simply "other comments" as a way to be humble/polite. It would be a cool form of hn etiquette.