Go to Socratic Electronics.
Kuphaldt's Socratic Electronics Project is less well known than his famous Lessons in Electric Circuits (allaboutcircuits). But Kuphaldt claimed that for his own students it has been even more useful than his Lessons (he did so in a post in 2004, see the 2nd point of his first post). The question and answers of Socratic Electronics are certainly a good addition to the Lessons: It is always a good idea to check your progress by trying to solve some questions.
Two things you should know when you look for questions to test your knowledge: First, the Lessons In Electric Circuits (allaboutcircuits) e-book and Socratic Electronics are independent projects (even though they were started by the same author) so there is not a direct correspondence between the volumes and chapters of the e-book and the questions in Socratic Electronics. But for most topics that are covered in the e-book you should be able to find a chapter in Socratic Electronics with questions that fit quite well. I would suggest that whenever you have finished a chapter in Lessons In Electric Circuits (allaboutcircuits), you go to Socratic Electronics and look for the corresonding questions to test your knowledge.
The second, and more interesting, thing is Kuphaldts philosophy behind the questions and answers (go to the openbookproject and look at the What is Socratic Electronics section near the top of the page). For some questions, especially when some value has to be calculated, Kuphaldt just gives a straight answer. However, the notes that follow the answer (and some of the more advanced questions) are intended to stimulate your own interest in doing some research on the topic, and to stimulate a discussion in the classroom. If you study Socratic Electronics on your own, it would probably be a good idea to use the allaboutcircuits forum as your classroom: After you have searched on the internet to find an answer and you still have questions, post them in one of the forums (do not be shy, it is a very friendly community, and they are especially helpful when it comes to answering the questions of a novice).
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