Using LM317 as chopper driver for small stepper motor

Grob Basic Electronics is a very good textbook.

Grob Basic Electronics 8th Edition

Anything by Albert Malvino is good.

Electronic Principles by Albert Malvino

As nilton61 pointed out, you don't need the very latest edition. Buying used saves you a -lot- of money.

I’ve not had a chance to do more than skim the text, but this looks like a decent online site with videos.

101 Science Electronics

I strongly applaud the very thoughtful comments and suggestions!

Sadly, I think they are likely to go unappreciated.

nilton61 hit the nail on the head with the point about "short cut thinking". These days, people are becoming addicted to Google and expect a quick answer to any question, even if understanding the answer depends on having worked through the equivalent of a semester or three of college level physics and/or electronic engineering.

Ah, I just remembered a post by calvingloster, he is 11, I believe.

You are getting a good start. Keep going. Learn the basic physics and electronics.