Starting this week, you can signup for a free online course in Circuits and Electronics from famed university MIT.
If you're curious enough about circuits and electronics, there's a way you can study it for free and online.
MIT is offering an "experimental" online course for free via its web site, called 6.002X: Circuits and Electronics. You don't have to buy textbooks (relevant passages are provided online), and lectures and interactive labs all happen online. There are exams, as well as homework.
We can't say it will be easy. While anyone can sign up, MIT recommends you have college-level physics in electricity and magnetism under your belt, as well as "basic" calculus, linear algebra and differential equation knowledge.
That said, for anyone who's tinkered with a soldering iron, built their own PC, or is fascinated by smartphone technology, this should prove interesting.
The course starts on March 5 and runs till June 8, and if you get through it you receive a certificate of accomplishment (electronic, not on paper). An MIT degree is something else entirely, and you can't get one this way. You need to be admitted to MIT first via a "highly selective admissions process".
Interestingly, you can also thousands of course notes, lecture notes and assignments for free through the OpenCourseWareConsortium - there are more than 2,000 courses from MIT listed there.