Reddit mentions of Electronics Sensors for the Evil Genius: 54 Electrifying Projects

That is fantastic, and I applaud you for independently expanding your knowledge base!

All electronic sensors and instruments utilize analog, digital, or mixed signal (which basically means analog AND digital within the same system) theories. My recommendation for that book stands. I think it's an excellent starting point, but it won't explain how you apply those theories in a useful manner.

As a Cal Poly grad, you know the whole "learn by doing" mantra and how effective it is. I recommend picking up this book. It has a lot of electronic sensor projects, as well as explanations behind the theory of operation.

Also, visit the MIT Free Online Course Material Website for some free lessons in EE.

Those should be good places to start. Lemme know if this information is at all helpful, or if you need further reading.

Here is the book on Amazon. Their "Look Inside" function shows a surprising amount of the book. Scematics and everything. If you google around, you might find a pdf to download too.