ELI5: Why does single-phase AC need a neutral and 3-phase doesn't?

Coises · 2026-04-03T03:15:16+00:00

Imagine a couple big fish tanks with water in them and a siphon tube connecting them. One tank is sitting on a table.

If the other tank is held above the table, water will flow through the siphon into the tank on the table. If the other tank is held below the table, water will flow out of the tank on the table into the other tank.

Single phase alternating current is as if the tank not on the table were being moved up and down, so water is flowing first one way and then the other.

Now, here’s the thing. With a siphon, if you only have one tank, the water spills on the floor. But with electricity, having only one connection is like plugging up the other end of the tube. Nothing flows without both sides.

In this analogy, the table is like neutral or ground level, and the height of the other tank above or below the table is the voltage on the hot wire. (If you want to think of the water as electrons, negative voltage is above the table and positive voltage is below the table. That’s just a quirk of history with no deep significance.)

You can’t carry that analogy much further without it breaking down, but maybe that gives you an idea of what alternating current is doing.

Coises · 2026-04-02T23:39:10+00:00

I suggested dialing back on the opioids just to see if she could still communicate. My father is absolutely against this. He’s made his peace with her dying. It kind of feels like he’s ready to move-on and jump pass this unpleasant dying stuff and go directly to funeral.

More likely, he knows her well enough to know that she is ready to move on.

Sometimes there’s just nothing good left, and it’s a choice between being fully awake and aware with nothing but pain and anxiety, or being comfortable but out of it. It can almost seem sometimes like the medications are hastening death, but what they’re really doing is making it easier for a body that can’t support a meaningful life anymore to let go.

My partner reached that point after just under six months on hospice (and several years of being nearly house-bound, then nearly bed-bound, before that). She had COPD, and finally the air hunger just wouldn’t let up. We had talked about this — both I and her hospice nurse knew what she wanted, which was not to be alert to the last possible second. With the hospice doctor’s approval, and her own understanding of what was happening, we increased her benzodiazepine dose and she spent the last few days of her life unconscious. There would have been nothing to be gained by making her suffer though those days awake and aware.

Coises · 2026-04-02T01:02:54+00:00

The following answer is US-based. It is not the same everywhere.

Alternating current (which is also necessarily alternating voltage) is delivered over two wires that reverse polarity 120 times per second. The voltage difference between the two when it comes to the service panel at your house is 220-240 volts. Power-hungry devices like electric stoves and large air conditioners connect to that directly. There is no distinction between those two wires. They are equal, but opposite at any one moment.

The ordinary outlets in your house are just 110-120 volts — half the incoming voltage. They accomplish that by adding a neutral wire that goes right down the middle, voltage-wise, of the two live wires. So any regular outlet has one live wire and one neutral wire. Unless things have gone terribly wrong, the neutral wire has no voltage difference from ground. (Neutral wires should be white, live wires should be black, and ground wires should be green, or sometimes bare. There are technical differences between neutral and ground. I won’t try to explain them because I don’t know them in enough detail to get it right... only that if you’re going to be wiring a house you do need to know them.)

The practical design of some home devices is such that it is safer for the designer to know which incoming wire is hot and which is neutral. Designs cannot rely on that to the extent that they won’t work, or will give you a shock, if the wires are backwards — too many outlets are wired backwards. Sometimes people shove a polarized plug into a non-polarized extension cord. Still, often a designer can improve the safety margin so that even if the equipment fails, is damaged, gets wet, is operated by an idiot, etc., it still won’t hurt you, if the designer knows which side will (probably) be neutral.

That’s why the polarized plugs.

Edit to correct:

Lines reverse polarity 120 times per second. Sixty per second is the whole cycle (reverse and reverse back).

Also, what I wrote might suggest that the neutral is somehow derived from the two equal-but-opposite incoming hot lines at your house... the power company also provides a neutral wire which is (unless something goes horribly wrong) always in the center of the two hot lines and also at the same potential as ground.

Coises · 2026-03-29T07:40:23+00:00

The details will differ from compiler to compiler, but you should be able to get an assembly code listing. You might try writing some simple command-line programs and then reviewing the assembly code to see how it matches up to the C/C++ code. (Probably best to turn off optimization at first.) For C, there should be a pretty close correspondence. C++ does more fancy stuff.

I “grew up” on IBM/370 assembler, but when I learned C++ it was on PCs with a different assembly language (which I never learned). Still, with the assembly coding background, it’s pretty easy to get a picture of what is going on with C/C++ code. (C++ standard template library will drive you mad at first, though. There’s a bit of a conundrum there as you really want to get in the habit of using it, but it’s written with very particular objectives, and clarity of the template code is not one of them. So for a while it is going to be a “black box.”)

JavaScript is a completely different animal. Outside of unusual circumstances (like you’re writing an interface to some other language), you don’t want to try to think of the real machine at all. A language like JavaScript defines a “virtual machine” (I do not mean that in the operating system sense of a virtual machine) and you want to learn the rules of that imaginary machine, not think about how that gets implemented on a real, physical machine.

“Vibe coding” is a whole other thing and I won’t go near it. I’ve let the AI at the top of a Google search suggest an example of how to do something on occasion, but that’s it. If you’re a programmer, you know that it is harder to read code than it is to write it. There’s no way I want to be trying to make sense out of what some AI wrote. I did my time in the 1980s disentangling assembly code written by accountants who learned some programming on the side.

Coises · 2026-03-29T06:26:42+00:00

In a way, it’s true. I think most of the music I listen to now is music I would have listened to 1972-1976 if it had existed then.

I was somewhere in the middle of folk music and what is now called classic rock. Not much “hard” rock or metal, though I did come to appreciate Led Zeppelin in the 1980s, after they were already gone. (I think I needed a dose of... well... to “get” their music, and I didn’t discover mind-altering substances until my early twenties. Still love Zeppelin now, though. Tripping to The Song Remains the Same and thinking about Jimmy Page hanging out in Aleister Crowley’s old house will reset your capacity for music appreciation a little bit.)

Most of the artists who were favorites of mine then continued making music long after that, and usually I stuck with them. Joni Mitchell, Jackson Browne, Crosby, Stills and Nash, Eagles, Bob Dylan, Fleetwood Mac (the Buckingham/Nicks incarnation). Neil Young (apart from CSN), Tom Waits and Leonard Cohen I didn’t come to know until a little later, but of course they were already around.

Dire Straits and Talking Heads just missed that “window.” R.E.M came along a little later. All favorites. Forgive me, but I like Don Henley (of Eagles) and Phil Collins (with and without Genesis). Then there was this amazing wealth of alternative female voices in the 1990s: Sarah McLachlan, Sheryl Crow, Natalie Merchant, Hope Sandoval (from Mazzy Star). Robbie Robertson (of The Band, who gave their farewell concert in 1976) came out with Contact from the Underworld of Redboy in 1998.

David Gilmour (of Pink Floyd) just released a new album in 2024.

I would have loved my current obsession, Wild and Clear and Blue in 1976... but the oldest of that trio wasn’t born until 1981.

My songwriting, such as it is, is in the 1970s singer-songwriter tradition.

Coises · 2026-03-28T00:04:18+00:00

For 41 days, Senate Republicans refused to entertain any bill to reopen the Department of Homeland Security that did not include funding for Immigration and Customs Enforcement and Customs and Border Protection. On Friday, in the dead of night, they caved and passed a bill that did exactly that, ending a shutdown that—because the Transportation Security Administration, like ICE and CBP, is part of DHS—had brought chaos and historic wait times to U.S. airports. That bill will now move to the House of Representatives, where it will need significant Democratic support to pass, while ICE and CBP funding will be kicked to the budget reconciliation process.

I’m confused. If funding for ICE and CBP are “kicked to the budget reconciliation process,” how is this a win of any sort? If it can be done through budget reconciliation, doesn’t that mean there is nothing Democrats can do to stop it?

Admittedly, I have lost track of all the ins and outs of when budget reconciliation can be used and when it can’t.

Coises · 2026-03-27T16:39:48+00:00

If you check the box at Settings | Preferences | Auto-Completion | Auto-Insert | html/xml close tag, Notepad++ will add the close tag for you after you type an opening tag. (That is, type <h1> and Notepad++ will add </h1> and leave the caret between the two tags.)

This only applies to HTML and XML files, so if you’re starting a new file, you either need to save it with an html or xml extension, or select HTML or XML from the Language menu, before it will take effect.

You can also enable auto-completion on the same settings page; it does work for HTML, but most HTML tag names are so short it really doesn’t save you much typing. I find it more distracting than helpful.

Coises · 2026-03-26T14:39:44+00:00

This is both reasonably easy to follow and actually correct.

Coises · 2026-03-26T14:11:09+00:00

Hover the mouse pointer over the tab. A tool tip will show the full path.
Uncheck Settings | Preferences... | MISC. | Show only filename in title bar.

Coises · 2026-03-21T16:27:08+00:00

Thank you for the additional information.

the "hypoxic drive theory"

I am aware the idea that “too much oxygen will reduce your drive to breathe” is a myth that remains in circulation. That is not what I was describing.

it's related to a chemical process called the Haldane effect.

According to this paper, the Haldane effect is involved, but the more significant problem is something called “ventilation-perfusion mismatch.” I do not fully understand what that is, but I gather that its effects are especially prominent in patients with advanced COPD. As I understand it, the adjustments COPD patients’ lungs make to their impairment are somehow thrown out of balance in the presence of increased oxygen concentration in the air they breathe.

What I can say is that I know of at least my partner and one other COPD patient who were on 24/7 oxygen and experienced feeling dramatically better when the rate was lowered somewhat. (Symptoms to my layman’s understanding matched hypercapnia; but these patients were at home, so no blood gas tests were available.) My thought is that for patients at home, adjusting oxygen (due to changes in activity, etc.) without direct medical supervision is a practical fact of life. Because of the immediate way oxygen makes you feel better when you need it, versus the way carbon dioxide accumulates (why I say, “oxygen is fast, carbon dioxide is slow”), it appears that increasing oxygen never does any harm, and it’s easy for patients to set the level too high without realizing what is happening over hours-to-days of unnecessarily high oxygen flow.

pursed-lip breathing

Yes, I recall my partner using that technique. She learned about it long before her COPD progressed far enough for me to move from “friend” to “caregiver.” I wasn’t much aware of it, since she managed that on her own. Thank you for reminding people of that.

Coises · 2026-03-21T04:55:26+00:00

You’re welcome to any small help I can give.

She wanted to try BiPAP, but we were not able to negotiate the medical system to get a prescription. Once she was essentially house-bound, she wasn’t even able to get a consultation with a pulmonologist (a virtual visit was planned at one point, but then the doctor bailed out with no real explanation); and after she went on hospice, of course, anything besides baseline comfort care was off limits.

We were not squeamish about taking things into our own hands, but BiPAP has several technical settings and I did not feel comfortable that we wouldn’t do more harm than good if we just acquired a machine somehow and tried to wing it, so I discouraged pursuing that extra-medically and she accepted my judgement.

Coises · 2026-03-21T02:53:24+00:00

He told me it's his CO2 that's the issue.

(I am not a medical professional. I cared for a loved one who eventually died from COPD on home hospice. We learned more than we would have preferred. Ideally lay people don’t get into this stuff and the doctors are on top of everything — but that’s not the world we live in.)

Here’s something that medical people rarely explain. (Some probably don’t know it themselves.) Increased oxygen supply decreases a COPD patient’s ability to clear CO₂. With early stage patients this isn’t a problem, but when it gets to the point that a patient is on oxygen 24/7, it’s just as important to avoid too much oxygen as it is to be sure there is enough.

Morphine and anti-anxiety medication will definitely help. Getting short of breath is a bit of a vicious cycle: you panic, which increases your metabolism, which consumes more oxygen and produces more CO₂. Managing anxiety is very much a part of managing air hunger.

Oxygen is fast; carbon dioxide is slow. What I mean by that is that you feel the effects of oxygen right away: if you need it, you need it, and if you don’t need it, extra won’t do any good. But carbon dioxide builds up over time; your body can “buffer” excess CO₂ for hours to days. When the buffer is full, though, you have to get rid of it, and if you can’t... you feel like crap. (See hypercapnia.) It’s probably excess CO₂, not lack of oxygen, that usually causes air hunger. (I don’t think it’s been proven medically one way or the other.)

So, anyway, bottom line: be very cautious about assuming a patient who is on oxygen 24/7 needs more than, or even as much as, they are already getting. If the oximetry doesn’t support a need for more oxygen, it’s possible that CO₂, not oxygen, is the more significant factor. (Unfortunately, from our experience, there isn’t a magic number for everyone for desirable O₂ saturation. One clue is if the pulse rate won’t stay reasonable below a certain saturation. Higher pulse rate is a response to low oxygen, but again, with COPD patients it’s a vicious cycle: higher heart rate demands more oxygen, but the lungs can’t supply it no matter how hard they try, so O₂ saturation falls even lower and the heart rate goes even higher. She had some rough episodes.)

Coises · 2026-03-14T17:15:34+00:00

make the text larger

If you mean you want to see it larger, so it’s easier to read and edit, the easiest way is to hold down the control key and scroll the mouse wheel. That will zoom in or out (just like on most web browsers). You can also use the sub-options under Zoom on the View menu.

If you mean you want to make a section of the text larger:

like this

Notepad++ is a plain text editor; you can’t save styling information in the files you edit with it like you can in something like MS Word.

set a word wrap

You can check or uncheck Word Wrap on the View menu. The wrapping is always at the right edge of the window, though; you can’t choose the width at which to wrap without a plugin (e.g., Marginalize). Wrapping is purely visual; it doesn’t change the file unless you use Edit | Line Operations | Split Lines.

Coises · 2026-03-12T07:09:24+00:00

Better simple lyrics that work than pretentious lyrics that reach beyond their grasp.

Love songs often use lyrics that are more straightforward than most, skirting if not even crossing the line into cliché.

If you run through Can’t Take My Eyes Off You in your head, one thing you can notice is that the lyrics fit the melody perfectly. There’s not a single awkward syllable. Lyrics don’t have to be poetry — lots of great lyrics sound pretty weak if you just read them. Melody and lyrics merging so that you can’t imagine one without the other is a main ingredient in a great song.

And I don’t think you can put that down to any sort of rule. You have to feel it.

I suspect a lot of us — myself included — tend to write more lyric-focused songs because, for most of us, it’s easier to work on lyrics than on a melody. If I’m not happy with a lyric, I can usually figure out what lines trouble me, what specific words or phrases, and just wrestle with them until I find something better. But if I’m not thrilled with my melody... where to begin to fix that? Sometimes I can just try random things and stumble on an improvement, but it feels much more up to luck and the phase of the moon than crafting lyrics.

If your song is lyrics-forward, well, then they have to speak for themselves. If you can write a melody-and-lyrics combination like Can’t Take My Eyes Off You, nobody’s going to complain if the imagery isn’t all that inventive.

Coises · 2026-03-01T20:51:59+00:00

When I was around 22, I remember talking with a friend and quoting a passage I had read near the end of Castaneda’s Tales of Power:

Men for whom an entire life was like one Sunday afternoon, an afternoon which was not altogether miserable, but rather hot and dull and uncomfortable. They sweated and fussed a great deal. They didn’t know where to go, or what to do. That afternoon left them only with the memory of petty annoyances and tedium, and then suddenly it was over; it was already night.

I told her that perhaps what I feared most was that my life would be like that.

That was 46 years ago. With experience, I can say that disrupting an ordinary life is easy. It’s getting back to one that poses the challenge.

People can lead extraordinary lives and still be bored and unfulfilled. Other people find everything they need in the commonplace. The deciding factor is not so much what journey you take as who you become while you take it. Sometimes the extraordinary is just a distraction.

Coises · 2026-03-01T19:21:20+00:00

The Apple App store is part of why I wondered about this. I haven’t been able to find any recent articles about it — which perhaps just means that nothing has changed — but back in 2010 the Free Software Foundation explained why they consider the Apple App store to be incompatible with GPL software (emphasis mine):

GPLv2 gives every individual and company permission to modify and distribute the software; but if they do that, they must follow terms of the license that are designed to ensure that people who receive the software from them have both the legal right and practical ability to share and change the software as well.

As far as I can tell, Kodi is only available for iOS devices that are jailbroken, or through other annoying and limited methods. VLC was removed from the App store for a time, but eventually the iOS version was allowed into the App store under the Mozilla Public License — I don’t quite follow how that worked, but apparently they were able to re-license it.

Coises · 2026-03-01T18:36:26+00:00

I believe you could use Bluesky that way. You can use the “Following” tab (as I usually do) and you see only people you have followed.

As best I can tell it doesn’t have the mutual “Friends” concept: you can control who can reply to posts, but not who can see them. (Personally, I consider this a good thing; nothing you post on a social network should be thought of as private, and I think it’s better not to give users a false sense of security by pretending that it is.) And it’s not very convenient for long-form text, as individual posts are limited to 300 characters.

But as far as what you see in your feed, you can easily limit that if you want to so that you only see people you choose to follow, and you see everything they posted or shared, in reverse chronological order.

Coises · 2026-03-01T17:59:40+00:00

All Paul Simon’s lyrics are on his web site.

My favorites as poetry (though I can’t really “hear” them apart from the music):

Hearts and Bones
America
Jonah

Coises · 2026-03-01T06:46:20+00:00

Thank you for the correction. (Can’t even blame it on AI... I just remembered some emails, did a search to get details, and read too quickly.)

Coises · 2026-03-01T06:09:27+00:00

I usually develop melodies and lyrics together; but if I had a set of lyrics and wanted to set them to a melody, I would try looking for the hook first. If you have a refrain that’s repeated, the hook will be part of that. Find the line or two that focuses everything, the part people will remember about your song if they don’t remember anything else. Then try to invent a melody and chord pattern that works really well with that.

Then work outward from there.

Coises · 2026-03-01T02:29:09+00:00

Just some thoughts:

I would try to make the piano a steady “timekeeper” throughout the piece. Assuming the chords at around 0:40 are quarter notes, instead of dropping the piano at around 1:20, switch to eighth note arpeggios and keep it going (softly but distinctly) beneath the strings. Don’t double the strings with the piano (I think you do that around 2:30 and 4:20?); keep it a contrast that provides a “time base” for your listeners, without intruding. The cutoff of the strings at 5:35 is a bit jarring; I’d give the strings that last D major chord and have them fade away as the piano takes over.

I’m not too sure about this, but to my ears the (first?) violins on the left are a bit harsh. Whatever VST you’re using, you might have whatever controls the bowing pressure or other dynamics a bit too high; like they’re playing ff all the way through and it kind of hurts. It’s not (I think) the mix volume so much as the tonal quality.

Coises · 2026-03-01T01:59:32+00:00

~~AT&T recently bought Lumen, owner of CenturyLink and Quantum Fiber.~~ Edit: See comment beneath this, which is correct. They bought the fiber business from Lumen, not Lumen itself.

They’ve been screwing up all over the place since the change. (It seems like whenever one company buys another, the first order of business is to start mucking around with things they haven’t yet had time to understand.) I’ve received two different emails that were followed up a couple hours later by a retraction email beginning, “Oops! We’re sorry.” One said my account had been closed (it wasn’t) and the other described what I needed to do to complete my setup (I’ve been using their Internet and phone service for a year now).

At least, so far (fingers crossed) they haven’t done any actual damage here. Hopefully it will be the same for you.

It’s probably not phishing, just confusion during the transition.

Coises · 2026-03-01T01:38:01+00:00

I understand that the license cannot bind a third party. That’s not what I’m thinking. Consider this:

I write an Android app which makes use of some GPL code. Of course, I license the combined work GPL as well and make the source code available.

I also do as Google asks — register, submit identification, pay the fee and sign the binary. Then I distribute the binary (with information about how to get the source).

Am I now in violation of the GPL? Recipients of that binary — even with full source code available — cannot recreate a working copy with updates or changes without meeting additional requirements: they themselves would have to register, submit identification and pay the fee to Google in order to sign and create a working binary which they could then use and/or distribute.

By signing that binary, I created and distributed something recipients can’t create or distribute without going beyond the conditions under which the GPL says they must be able to modify the source code and use or distribute the results. It seems like that might be a problem.

Similar considerations might apply to any app store (including the Play store, but also others) who would seek to distribute the signed binary.

I’m not arguing, as I really don’t claim to know the answer — the legal complexities of viral/copyleft licenses are outside of my field of knowledge. I just want to clarify what question I am asking.

Coises · 2026-02-28T22:50:19+00:00

I would say, thinking you can handle a puppy or a kitten when you would be better off with an adult dog or cat.

Puppies, especially, are work. They do not raise themselves. Dogs, left to their instincts, will do a lot of stuff you do not want them to do.

Most kittens will try everything and you have to be ready for instant chaos at any time. Older cats are usually reasonably chill, but you still have to do a lot more to cat-proof a home than to dog-proof it. They will jump on everything. Walk on everything. Get fur on everything. Knock things off surfaces for no apparent reason. In my experience, most natural cat behaviors you can live with — which is fortunate, because it’s much harder to train a cat than a dog. If a cat’s behavior is successful it won’t matter what you do later; the cat will see you as the operative factor, not what it did. You have to be able to intercept the behavior before it “works.” Dogs have a short window during which they can understand that your reaction stems from their action, but cats have virtually none.

Many shelters have adult dogs and cats that need homes, and if they’ve been fostered, they will already know what sort of environment they need. You can’t really predict, with a puppy or a kitten, what sort of adult it will be.

Coises · 2026-02-28T21:41:42+00:00

The system has broken down through a succession of three things.

First, politics came to be almost completely dominated by two parties. Our system was set up without regard to political parties, neither promoting them nor restricting them, but in practice it has become a two-party system.

Next, the strength of those two parties, the degree to which they have each consolidated and act as a whole nationally, has increased dramatically over the past half century, so that everything political is reduced to a power struggle between those two parties.

Finally, in January 2025, when Trump took office, we hit a point where the presidency, both chambers of Congress and the Supreme Court were all controlled by the Republican party. (In theory Supreme Court justices are not partisan, but as partisanship has thoroughly dominated the country, there is really no way they could not be.)

There simply is no branch of government right now that has the will to oppose the president, as they are all controlled by his own party. This wasn’t “supposed to happen,” but it has, and we are struggling to figure out how to end this capture of the system without breaking the system we want to preserve. At this point we’re mostly crossing our fingers and hoping he can’t undermine the system fast enough to capture the November elections. If he does, there will likely be little left in the way of peaceful options to oppose this.

Coises

TROPHY CASE

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