Barrel jacks were awesome, they could go in any orientation. The only downside was the many different forms of barrel jack and lack of a standard. My question is: why isn’t there a cylindrical USB port? You would be able to rotate it any way you want within 360 degrees!
As a matter of fact, why isn’t there a cylindrical power plug? You’d get the benefits of a recessed plug like Type-C (EU) and Type-F (Schuko), you’d get the benefits of reversible plugs like Type-A (North American) and more so as you get 360-degree rotation, and it would be MUCH harder to break/bend compared to two flimsy pins (the UK plug has three thicker pins, but a chunky cylinder would be much more difficult to bend than the pins)
If it was a hollow cylinder (a bit like a vacuum-insulated water bottle), you could feasibly fit some small electronics in it, so things like flush low-power USB chargers and smart home sensors could be made.
The contacts would likely need to be outside the cylinder, similar to the “neutral” pins on Schuko plugs. There would likely need to be some plastic tabs to keep the power bits from touching the non-power bits, and then the socket itself would be able to freely rotate.
Actually, why don’t regular sockets freely rotate? Then it would solve all the issues of non-reversible plugs not able to go upside down and reversible plugs not able to go sideways.
Speaking of cylindrical objects, what happened to camcorders? They sound like the most comfortable and easiest way to record videos, with straps and everything. They were compact, portable, and wasn’t heavy as all heck.
this is my rant about cylinders, thank you for your time.
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There are two immediate problems with round USB. First one is that audio jack carries no power and it’s generally rather harmless for finals or microphone to have some contacts shorted or crossed for time when plug is inserted. USB, let’s even day just 4-pin, carries power and i’m not sure how well would either of devices react to having data bus connected to +5
The other problem is that USB is proper radiofrequency connector, unlike audio jack where anything goes. This means it has to be shielded and impedance has to be some specified value, which in practical terms means that there’s some specific ratio of metal to plastic and shape of conductors that has to be used. Barrel plugs would have way too low impedance and already bulky connector needs extra shielding which makes it even bigger
Ipod Shuffle and the TS80P soldering iron both use TRS for power transfer.
i don’t think you’re supposed to hotplug soldering iron tip. besides it’s a simple thing, isn’t that just two resistors - one for heating element and another for measuring temperature? hard to break that. not sure about how ipod shuffle worked or what precautions were needed. also today USB can deliver power at higher voltages than it used to
Speaking of cylindrical objects, what happened to camcorders? They sound like the most comfortable and easiest way to record videos, with straps and everything. They were compact, portable, and wasn’t heavy as all heck
Smartphones happened.
Usb c has 24 pins. A typical barrel / stereo style jack has 2 - 4. The connector would have to be absolutely huge to carry the number of wires.
Power plugs are similar problems. You need 3 wires and you can’t risk the pins crossing over each other and shorting out. You don’t care about that on your headphones due to the low voltages. Wall plugs need to be fully isolated and safe.
power plug with 3 wires or 5 wires (3-phase) could be made safe-ish if there was a button at the very end that connected to a relay or something. but plug like this would be comically long for any practical power
oh yeah usb has loads of pins for data. no wonder barrel jacks were never used to transfer data…
oh yeah designing an idiot-proof power plug that can be rotated 360 degrees would be challenging ad well
Round connectors were absolutely used to transfer data, for example audio and video in the form of RCA plugs and many other examples back in the day. Another example is coax cable for TV signals (both analog and digital) and also LAN.
However the lack of distinct interface channels leads to a bottleneck in bandwidth. So as the need for bandwidth increased many of those were replaced with multi pin versions. This is much harder to do with round connectors and there isn’t that much benefit, so they mostly got ditched.
However round connectors still have their place, for example tiny little coax connectors found in many devices to carry signals. Wifi antennas and such are connected this way.
Coax has only 2 conductors and it keeps impedance constant, unlike audio jack
The 3rd gen iPod shuffles used the headphone port for USB, definitely uncommon though.
to add to this answer, those 24 pins would have to be aligned correctly.
so, you’d have this problem, but worse because because it’s round and not basically flat:
Cordless kettles manage to connect mains power with a round, freely turning connector, so it can be done safely
Well, those ones does it at the cost of size. In order to ensure separation they are comparatively huge.
A cylindrical connector would be fine for connecting one or two conductors. But more than that and it starts to become a nightmare to design, and even worse to build and use reliably. Classic examples include the venerable RCA connector, the BNC connector for radio signals, and IMO the worst connector to ever exist, the F-type connector used for TV coaxial cable.
With just two conductors, a cylinder can have have a concentric shape, where the inside is a pin and the outside is a shell. But you’ll notice that although all these connectors are circular, they’re hardly designed to rotate while attached. You generally have to remove or at least loosen them before trying to turn them. Or you still try it and the TV picture might flicker a bit. The problem is one of electrical contact.
The engineers that make connectors go through painstaking efforts to get the conductive surfaces to align – or “mate” as they say – because if they don’t, the signal quality drops like a rock. It’s already hard enough to get cheap connectors to reliably align, but now you want them to move relative to each other? That’s tough to build, and moving surfaces will eventually wear down.
Even worse is that circular shapes tend to have poorer mating, because manufacturing tolerances for curves is wider than tolerances for flat surfaces. We actually don’t want to make round contacts, if a rectangular shape would suffice. Flat contacts are simpler to produce and generally more reliable [citation needed].
But even more intractable is the matter of matching the pinouts. Here is the pinout when looking at the connector of a USB C cord:
Even without understanding what each pin does, it’s noticeable that certain pins are the same whether you flip the connector over. In fact, they even label them that way: pin A12 on the top-right is also B12 on the bottom-left. The most damaging scenario is if USB 5v power was sent down the wrong pin, but it’s very clear that the VBUS pins – which are the 5v power – will always be in the same place no matter the cord orientation.
The only pins which are different upon inversion are the data lines – anything with a + or - in the name – or certain control signals which are intentionally paired with their opposite signal (eg CC1 and CC2). The USB C designers could have packed way more data pins if they didn’t have to duplicate half the pins to allow flipping the connector over. But that design choice has made USB C easier to use. A fair tradeoff.
And that’s the crux of it: in engineering, we are always dealing with tradeoffs, either for performance, cost to produce, ease of use, future compatibility, and a host of other concerns. Wanting a cylindrical connector could certainly be a design goal. But once it starts causing problems with alignment or manufacturing, there will inevitably be pushback. And it’s clear that of all the popular connectors used today, few are cylindrical.
Heck, even for DC power, the barrel connector has given way to more popular designs, like the Anderson PowerPole or the XT family of connectors, because the market needed high-current connectors for drones and Li-po batteries. Granted, the XT connectors are basically two cylindrical connectors side-by-side haha.
woah that’s a very in-depth answer. yeah makes sense that cylindrical connectors aren’t actually designed to rotate a bunch. I assume it would be something similar to weird crackling sound when you turn an 3.5mm jack cable too hard?
I’m not sure how hard you’re rotating a 3.5 mm cable, but yes, that sound is the sudden making and breaking of the contacts, which it’s not meant to do. It will wear down the surfaces, even if the 3.5 mm tip is gold plated, since the gold is for anti-corrosion not for anti-friction.
But, the notion of cylinder housings for connectors has not died. After all, large cylinders are easy to grasp. Here is one very beefy example, often called the California Standard connector due to its use for Hollywood movie productions. This is a waterproof, twist-lock connector that also suppresses arcs if you unplug it while it’s still on. It can only connect in one orientation, so you keep rotating around the center pin until it slots in. It’s heavy enough to probably also double as a blackjack for self-defense lol
What’s your beef with the F-type connector? The centre pin is the coax core, compression tool to terminate the coax, solid connection, rated to some absurd frequencies, all round easy connector, no soldering or extra pin required.
Source: I installed two-way satellite dishes for a time and still use those connectors on my HF antennas as a radio amateur - yes, I know, 75 Ohm - can’t say it’s ever stopped my 10 mW beacon from being heard 13,945 km away.
In not the person you replied to, and I can’t speak about the engineering merits; but as a user I hate F-type connectors. They’re bad enough when you have to only install them once in the lifetime of the connected device - it’s the threaded screw that’s the worst, I think, for which no non-technical user owns a tool beyond their fingers, from which the bevel invariably strips the flesh; although I’ve also bent enough of those pins trying to get something connected in an awkward place, or because I was tired, or being sloppy. It’s not a connector that’s convenient for amateurs, and most of its users were and are amateurs.
As a connector for multiple, frequent dis- and re-connection, it’s an utter disaster. Sure, that’s not what it’s designed for. It was designed to be a semi-permanent extension of permanent wiring, and I’m sure it’s great at that.
The context of the whole thread, though, was end-user, repeated, frequent connections for people who have to be reminded by a manual that the thing needs to be plugged in. Coax is horrible for that.
The context of the whole thread, though, was end-user, repeated, frequent connections for people who have to be reminded by a manual that the thing needs to be plugged in. Coax is horrible for that.
so you want BNC
It is my understanding that Apple actually wanted to use 3.5mm jacks for their ADB keyboard/mouse interface in the early days, and some prototypes exist which used the jacks.
https://www.applefritter.com/node/294
The plug manufacturers couldn’t guarantee that you wouldn’t sometimes get high resistance issues if the plugs were left connected all the time. On a pair of headphones you’d hear that as static and turn the plug or unplug/insert to get it going again. But you can’t “hear” through a keyboard.
They used mini DIN 4 instead.
If they keep being rotated they wear out easily.
fair point, makes sense
Can confirm. I used to fidget with the charger on an old laptop of mine by just spinning it in place in the port. Over time, it loosened up the connections to the point where I had to duct tape the plug into the port.
Because of all the pins involved with USB, I think these would end up bring more like the mouse plugs of yore. USB C seem pretty awesome to me for this scenario.
As for a “wall” plug, given the voltage there, maybe there are technical challenges with safety? This is an interesting thought to me, i haven’t really thought much about wall plugs haha. There is so much room for improvement in my country (USA).
those old ps/2 mice and keyboard plugs were annoying as hell. definitely not designed to be easily hot-swapped.
Could they even be hot swapped? I don’t remember trying. I remember my dad getting a CD-RW drive with a USB-A connector, I had to reboot to get the computer to recognize it, but that was Windows 95 or 98.
Win 98 was when they started “plug and play”
Some of the ps/2 things were also plug and play but that partly depended on the hardware, and sometimes you had to tell it to go look for it. But rebooting was easier to do. Unless there was an update….
They could be, but that wasn’t standard behavior. When laptops started to become a thing it was realized that having hot swappable peripherals made too much sense to ignore, so some devices had improved ps/2 ports and controllers that could do that.
I see. I bought my first laptop in 2013 (used), and by then I was pretty ensconced in Linux. That machine didn’t have those ports.
idk, honestly any worldwide wall plug standard would be amazing, I wish the governments of the world focused on issues as simple as these
In a sense, we already have one. And it’s used on the vast, vast majority of desktop computers, it’s the standard for removable cords on electric kettles around the world, and it shows up in all data centers. I’m talking about IEC 60320, sometimes just called the “IEC connectors” or for one very specific connector, the “PC plug”.
For the task of attaching AC power to an appliance, this is probably the one with the greatest adoption worldwide. And there absolutely could be a wall-mounted version of these, the same way that datacenters essentially have power strips – ok, they’re RPCs lol – with these connectors.
Their only noticeable drawback is that the voltage can be anything up to 250v. So plugging 120v appliances into an Italian 230v outlet would be bad. But this family of connectors – formally called “couplers” – was meant to match current-capacity, where a mismatch would cause a fire due to overload. It’s still the user’s responsibility to check the voltage, in the same way that buyers have to check the type of battery they need for a remote control (eg AA vs AAA).
yeah those pc plugs are nice. if someone figured out a way for the cable to detect whether a device is 230/240V or 120V and make it stop giving power if there’s a mismatch, that would he really cool. sadly, that’s probably not possible, and even if it was, it wouldn’t be widely adopted. sad.
Or… we could just make appliances that are tolerant of the world’s different AC voltages. The world’s commercial electric grids only use a handful of voltages, and they’re all between 100-240v. Compressing the list by removing voltages which are within less than 10 volts, the list is quite short: 100v, 120v, 230v, 240v.
That’s all there is. And it’s exactly why most USB phone chargers list their input voltage as:
100-240. Today’s modern switch-mode power supplies can properly tolerate any of the world’s voltages, as long as you adapt the connector. The voltage side of things is mostly solved, except maybe for cheaper, motor-driven devices. But even that is changing to use inverter technology that can take almost any voltage.
For certain high voltage applications , like public PA systems, 1kw+ light and lasers, there are a still cylindrical plugs pug they use pins a bit like the old ps/2 port
another downside to cylindrical usb plugs would probably be thinness, USB-C ports are quite a bit flatter and suits thinner devices a lot more
Why does the majority of your post read like you don’t know these exist? https://en.wikipedia.org/wiki/Coaxial_power_connector
They’re fine, but as you mentioned in the first paragraph, lack of a standard is their main drawback. You could find two power supplies with the exact same connector but different voltage and polarity.
I read it more as asking why a USB-C went with an oval shape instead of a circle
The first words in the body of his post are “barrel jacks” so to me it definitely reads like he knows exactly what they are and they are what inspired his post.
Since other, probably more common, names for “coaxial power connector” include things like “barrel plugs” and “barrel connectors” and such terms are used pretty frequently in the article you linked.
The rest of it feels like he’s just trying to explain the concept to people who aren’t as familiar with them.
But otherwise I agree with your comment, the lack of a standard is a big reason. In my various bins of wires, cables, and adapters I can find plenty of different mismatched wall warts with the same connector but otherwise wildly different specs. You don’t really want to be mixing and matching those all willy-nilly.
Also they’re overall a fine connector if all you need to do is deliver power to something, you only need a hot and neutral wire and the corresponding part of the inner and outer part of the plug (I feel like I’ve seen some that have a ground too, but don’t quote me on that, I’m not going to go digging through my bins to confirm that)
But nowadays we also often need a way to carry data to/from the device in addition to charging it. So to carry those data signals in addition to power you’d need more connections in the plug. You’d need to either have a couple pins inside the barrel which would need to be lined up properly which kind of negates the convenience of it being omnidirectional like OP wants (think maybe something like a ps/2 or S-Video plug) or you’d need to have multiple concentric rings which would make the plug bulky, probably too much so to conveniently fit into something like a cell phone.
Now a lot of the devices we’re charging by USB don’t necessarily need or even support any sort of data through their ports, and so could be charged or powered just as well through a barrel plug. So why USB?
IMO a lot of it comes back to iPods. For a lot of us who were around in the pre-smartphone days, that was our first experience with something that charged over USB. I seem to recall that apple didn’t even include a wall charger with them (pretty sure I remember a Foamy the Squirrel flash animation where he ranted about that) you just got a USB cable and either charged it off your computer or you went out and bought a wall adapter.
I’m sure that was a cost-cutting/cash-grab attempt by apple. They could sell you an iPod without a charger and save a few pennies there, and then also sell you a charger for even more money.
Around that same time, phones were also getting USB ports, or some proprietary connectors that you could buy an overpriced cable to connect it to a computer via USB so that you could pull your .5 megapixel flip phone photos off of it and post them to your Myspace. Often they came with a charger that had a mini or micro USB port or the proprietary connector on one end and was hard-wired to a wall wart on the other end.
I’m sure some bean counters at Nokia or Motorola or wherever decided “why the hell are we going to add 5¢ to the production cost of a phone to have a charging port and a USB port for data when USB already can deliver 5v of power? Just build the phone battery around that and nix the charging port”
And I’m sure that played out with plenty of other devices that needed power and data connections- GPS, PDAs, etc.
And so from there, people started having an iPod and cell phone in their pockets that both charged over USB, and before long they’d have a USB charger at home, at work, in their car, in every room in their house, so other devices kind of latched onto that as sort of a marketing thing “you don’t need to keep track of a separate charger just for this thing, you can use the same one you charge your phone with”
And of course before too long TVs, game consoles, AV receivers, etc. all got USB ports too.
As I recall, it mostly started with things that made sense, things you were probably using with your phone or computer anyway- Bluetooth earpieces, mice, keyboards, etc. then sort of branched out into everything else over the years.
wdym? I did say the advantage of USB-C was a universal standard. that’s definitely why everything uses USB-C, much more convenient.
My later paragraphs were focusing on a theoretical cylindrical wall plug (hence the comparison with the euro plug, schuko, uk plug, etc). sorry if just “plug” wasn’t clear.
Telephones in Germany had round plugs until after ww2. The plugs were very convenient and also very bulky. They got replaced with much smaller plugs with more pins.
There is a lot more information being handed back and forth between the thing giving power and the thing getting power than we used to rely upon. Its not that cylindrical plugs couldn’t be done, but they would probably need to be much larger than is strictly necessary. The jacks would be necessarily larger to accommodate.
Old barrel jack type equipment is incredibly dumb, as in it has very little information passing back and forth.
i wonder how many pins could you fit with modern technology on something the size of a 30-pin connector? would that mean you could get more data/power being transferred? (the wire would have to get way thicker though)
Of course there are:
