I was never strong with normal modes myself, but a good text to refer to for a lot of classical mechanics stuff is the one by Taylor. However, from what I remember from the practice tests, some of the pendulum problems only required a qualitative understanding of the normal modes, so I'm thinking that you may be able to eliminate answer choices by first developing a mental picture of what the normal modes look like.
For electronic circuits, I look at my freshman physics texts (Serway, Giancoli). A modern physics text (or an extended version of a freshman text like Halliday/Resnick) is good for things like semiconductors, diodes, transistors and stuff. For E&M, Griffiths is the best, but I agree that it's overkill.