Hacker News Reader

Comment by butterNaN | Hacker News Reader

A gem of a book. Also check out "Bad Circuits": https://artofelectronics.net/bad-circuits/

I liked the book but I would like a lot more detail on why the bad circuits are bad. Some are obvious but I thought a few were quite difficult to understand the issue.

I can appreciate the point of view that self discovery of the answer is an important path to learning, but you never know if you are learning the correct lesson. I fortunately had a understanding chief engineer who helped guide me in my early career before I moved to software.

Nice find. What would happen to the 1st circuit, isn't it still a parallel circuit?

Assuming you mean the one labeled "voltage divider", the problem is that it doesn't actually divide voltage because the input and output are switched. The unloaded output voltage is the same as the input voltage.

Thanks for your helpful comment! I was also struggling with the bad circuits voltage divider.

Sure thing! One of the things that helps me sometimes is re-arranging things visually.

A real divider:

  Input o----vvvvv----o-------------o Output
                      |
                      |
                      Z
                      Z
                      Z
                      |
                      |
                      o
                    Ground

The bad one:

  Input o-------------o----vvvvv----o Output
                      |
                      |
                      Z
                      Z
                      Z
                      |
                      |
                      o
                    Ground

Looking at it this way, it might be a bit easier to see that in the good circuit, both resistors can be in a Kirchoff voltage loop that includes the input, while in the bad one they can't.

(Edit: it appears I don't understand linebreaks on HN, so things are gonna appear garbled until I fix it.)

(Edit 2: Fixed.)

Reply on news.ycombinator.com