# Thoughts on "The Art of Electronics" 2nd Edition by Horowitz & Hill?

#### WBahn

Joined Mar 31, 2012
26,398
Not sure how you came up with that conclusion??
As I noted, purely by statistical likelihood. Because the proper use and treatment of units is so poorly taught, the a-priori likelihood is overwhelmingly in favor of any one person, including you or me, not using them properly. Like all such statistics, place that bet every time will mean that I will be correct most of the time, but also guarantee that I will occasionally be wrong.

Joined Jul 18, 2013
25,001
, purely by statistical likelihood.
Oh...Oh I've been a victim of Statistics.
Max.

#### WBahn

Joined Mar 31, 2012
26,398
Oh...Oh I've been a victim of Statistics.
Max.
Probably.

Or not.

When you are finding the current through a 200k ohm resistor that has 7V on one side and 3V on the other, do you go

(7-3)/200 = 20 μA

or do you go

(7V-3V)/200kΩ = 20 μA

religiously, every time?

Are you comfortable with something like

v(t) = 15sin(t)

or do you cringe (twice)?

EDIT: I had written 20mA originally. I was battling a pretty bad migraine at the time and so I didn't do something that I normally do -- and harp on -- which to ask if the answer makes sense. In this case, I would have done something like, "Okay, the resistance is on the order of a megaohm and the voltage is on the order of a volt, so the answer should be in the microamp range. Since I'm underestimating the numerator and over estimating the demoninator, it should be considerable more than one microamp." Then, when I ended up with 20mA, it would have rung alarm bells (in addition to the one it already felt was going off around my skull).

But that all just underscores my point. I have never claimed that I don't make math errors -- if anything I probably make more than most. And I have never claimed that tracking units will catch every mistake -- I usually point out that it won't. I do point out that you need to be religious about using them and about asking if the answer makes sense -- and the fact that I failed in that goal resulted in an easily caught mistake that didn't get caught.

Even so, however, if this were part of a longer computation -- even many pages -- once the fact that an error was make somewhere because apparent, tracking down and finding the error would have been very straightforward.

Thanks, Max.

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Joined Jul 18, 2013
25,001
I would have to mark your paper wrong.
Max.

#### WBahn

Joined Mar 31, 2012
26,398
I would have to mark your paper wrong.
Max.

Or, more specifically, I can think of contradictory ways to interpret what you are trying say and so don't know which might be correct.

Joined Jul 18, 2013
25,001
I know my grey matter is shrinking but I make it 20μa?
Max.

#### WBahn

Joined Mar 31, 2012
26,398
I know my grey matter is shrinking but I make it 20μa?
Max.
And you would be correct. That's what I get for doing math with a migraine.

#### atferrari

Joined Jan 6, 2004
4,577
And you would be correct. That's what I get for doing math with a migraine.
Migraine, was just a word and a suspicious one for me (only suitable for romantic ladies in novels) until my youngest daughter found herself, victim of that.

At 22, nowadays she's still struggling with it. The very few times I felt headaches I understood how bad she could feel. Nature, I always say, is cruel before anything else. Pain makes no good to anyone and serves no purpose. That is cruelty in pure form.

#### WBahn

Joined Mar 31, 2012
26,398
Migraine, was just a word and a suspicious one for me (only suitable for romantic ladies in novels) until my youngest daughter found herself, victim of that.

At 22, nowadays she's still struggling with it. The very few times I felt headaches I understood how bad she could feel. Nature, I always say, is cruel before anything else. Pain makes no good to anyone and serves no purpose. That is cruelty in pure form.
I was in junior high when I suffered by first migraine and the loss of vision that preceded it terrified me and the headache itself convinced me that I was literally dying from some brain aneurysm or something. In the decades sense, I have gone through periods in which I would get one or two a week and other periods in which I would go a year or two without one.

Regardless of whether I am in a migraine drought or flood, I still get normal run-of-the-mill headaches on a pretty regular basis, ranging from mildly annoying to pounding. But migraines are on a completely different plane of existence and can completely incapacitate me for hours, sometimes literally leaving me whimpering and unable to move because the motion causes such intense throbbing pain.

As for pain not serving a purpose -- in general it serves a very useful purpose (though I can't see the purpose that migraines -- or most headaches -- serve). If we didn't feel pain when we put our hand over a mist of steam, we would have no reason to pull our hand back -- rapidly. As a diabetic, one of the problems I may well face someday is diabetic neuropathy in which I will loose sensation in my extremities. This is a leading cause for diebetics losing their legs because they don't feel the pain associated with foot sores and wounds and, therefore, don't get them treated and allow infections to set in and spread.

But, enough of this hijack.

#### Georacer

Joined Nov 25, 2009
5,182
I think that it's a good idea. Especially since it might foster comments on how people in different fields, such as IC design versus aircraft design versus utility grid folks, typically use the various symbols and terms.

Having said that, I wish we didn't have to many stickies in most of the forums. I would prefer to see a single sticky and have the lead post be a set of links to individual threads in a "Sticky Forum". This would keep the top of the forum lists clean of the clutter that forces you to scroll down to see the actual threads and would also make it easier for someone to peruse the Sticky Forum to see what key information is available or to search its posts for specific points.

Perhaps I'll suggest that to the powers that be.
I feel the same way, but I haven't yet found a way to compress the stickies. Their whole point is to draw attention, to begin with.

Joined Jul 18, 2013
25,001
An example that is typical of universal electronic symbols.
(Ahem.. notice the difference in Ground/Common symbols).

The current Electronic standards are:
IEC 60617 AKA BS3939 (UK)
ANSI Y32 AKA IEEE 315 (N.A.)
JIC EL-1-1973 (older N.A).
AS1102 Australian
http://www.rapidtables.com/electric/electrical_symbols.htm

IEC and BS 3939 (British) Logic.symbols differ from N.A.
http://en.wikibooks.org/wiki/Practical_Electronics/Logic_symbols

The customary method of schematic layout for N.A. and UK has been for the circuit to progress Left to Right with a logic result ending up on the right hand side,. and then the next progress downwards.
The European method tends to be from across the top of the page each logic string progress down the page and the logic result end up at the bottom of the page.
The next string progressing in turn across the page.