Hi HN! I decided to release the first few chapters of an online, interactive electronics textbook I've been working on for the past several months.

It's interactive because every schematic in the book can be clicked to be open it in a new tab. Many / most have simulations attached. You can generally change/add/delete any component and re-run the simulation to see the effect.

So far this covers about half of a first-semester undergraduate electronics course.