It's interesting that this is a brushed design. In the RC car community, brushless motors are generally regarded as superior, but those of course have the rare earth magnet problem.
Technically the brushes can wear out, although there are claims they are good for 150,000-250,000 miles it seems.
It's technically not a brush but a slip-ring. The design of these motors is very similar to automotive alternators, just scaled up 100x (in terms of power).
Brushes are used everywhere for transmitting electrical current between two parts that have an unlimited relative motion.
Brushes are typically made of graphite mixed with some binder. The graphite conducts the electrical current, but it also acts as a lubricant.
The metallic part that is in contact with the brush is called a slip ring, if it is continuous, like in synchronous motors, or a collector ring if it is segmented, like in DC motors or single-phase motors with brushes.
yeah I misspoke, I meant to say that it's a brush riding on a slip-ring (continuous contact, no arcing, lasts long) rather than a bunch of contacts in a cylinder (commutator, arcing, wears out).
Because it's the discontinuities in the commutator where the sparks fly (with much help from self-induction of the motor's coils) and erode the ring and brushes.
"Brushless DC motors" are good because brushed DC motors are constantly switching polarity, which causes arcing of the brushes, which causes wear. The brushes are not there to energize the rotor; the rotor is just magnets after all. The brushes are there to tell the stator to change polarity.
Brushless DC motors don't arc -- because they switch stator polarity with electronics that sense the position of the rotor without rubbing parts. (They can also fine-tune the stator current spikes to make the motor very efficient over a wide speed range, which brushed DC motors cannot do.) The lack of arcing is more important than the fact that they don't have rotating contact points.
Brushed AC motors have rotating contact points (slip rings) but they don't arc (ideally), so the contact points don't degrade as fast as brushed DC motors do. But they do carry a lot of current because their purpose is to energize the rotor. Brushed AC motors are not ideal, but making an AC motor "brushless" is not nearly as big a win as making a DC motor brushless.
Wait. You're saying DC motors require current that's constantly switching polarity? So they're sort of really AC internally?
Yep. All motors require constantly changing current. The distinction between AC and DC motors is whether you feed the motor externally with current that is already alternating sinusoidally, or whether the motor itself turns external DC into some kind of AC.
Similar situation, one thing I like the with the Pis design is you can throw PoE hats on them and build a whole home infrastructure system where the only thing that needs battery backup for power cuts is the main ethernet switch - all of the essential services, switches and wifi APs are powered downstream by their ethernet ports over PoE.
Makes making your key network services (VPN, firewall, DNS, NTP, home assistant etc) on battery backup very easy, as just one plug to the primary switch to keep powered, and my wifi/internet stays on when the power cuts.
I could use other devices, but 5 pis with PoE hats rack mount very cleanly in a single 1U row and passively cooled with no fan noise etc.
And GPIO support for your used office equipment is often just a cheap USB adapter away too, GPIO support is not some Pi exclusive thing, even if its 40 pin layout is widely used now etc.
The APIs in iOS that turn feature flags on/off as you travel now have gotten insanely complex. Some are on time triggers, some change instantly, some depend on where your iCloud account was setup, AFAIK there isn't a black and white answer as to what happens when you move a non-EU iPhone through Europe anymore, "it depends". It's similarly vague in the other direction.
Apple themselves have claimed recent EU compliance has led to over 600 new or changed APIs in the OS.
I've spent a fair amount of time with my iPhone in both the EU and the USA, have local cell service registered in both regions. its nothing as simple as a geo-location check anymore. It's a problem that has grown more complex over the decades too, as more and more countries implement their own slightly differing legislation.
I know a few folks who work in FTC compliance roles at Meta. I don't think the wider nerd-sphere appreciates the extent to which the FTC regulates Meta following the consent order after their privacy scandals of the 2010s, or the sheer number of roles within Meta now working only on FTC related compliance. I'm sure Zuck is no doubt desperate to ramp it down.
I've hoped for years someone would pickup the source and get it going again, it's essentially abandonware right now, no changes in nine years. The website is like a time machine back to the peak skeuomorphic mac app era. It still has the nicest UX of any of the DosBox variants I've tried. In this era of agentic rewrites, modernizing this app is probably the cheapest it has ever been too...
> It was a "microcontroller" you could program in Python with a friendly Linux environment and is now an expensive, power hungry, hot computer with a microcontroller hanging off of it
The Pi project was never originally a microcontroller - it was always a full-blown SBC you could program any way you want with some GPIO pins attached. People literally used them as (slow) home computers.
The company didn't sell its first microcontroller until years later in 2021 with the Pico, by which point we already had Pi 4. I do though think its a real shame prices for the SBCs have risen as they have.
At one point, the raspberry pi was a decent option if you wanted something hobbyist friendly that could toggle GPIOs and connect to the Internet (and later Bluetooth).
I suspect Espressif has mostly taken over that market now
The pi, particularly the pi zero is still useful if you need something that can run normal software but not a full mini pc. One example I've seen is using a Pi zero as a "wireless usb" where you can plug it in to a machine that accepts files over usb, and can now drop files on to it over the network.
Maybe you could do this with a ESP32 but it's easy on linux where you can use all the normal tooling and filesystem drivers.
ESP32 can run FreeRTOS, and I think people nowadays have no idea how much stuff we could do in MS-DOS PCs even with all their limitations for the epoch.
ESP32 hardware is much better than they used to be.
Not everything needs to be under Linux monoculture, thankfully.
I have yet to even get started with ESP32, mainly because software-defined radio is my main use case. Once you start getting into absurdly high sampling rates, you start to need a lot of horsepower, and that's where the more powerful SBCs shine.
As an example, one of my Pi 5s takes an Airspy and an RTL, extracts 11 different FM broadcast stations, then encodes each audio stream and sends all of them to an Icecast server. There's processing power for more stations, but there are none I'm interested in among the others I'm streaming. With the current 11, it's using about 75% of CPU resources with no overclock. (Edit: this is a 2GB model, and it's running in roughly 500 MB.)
It's still true that people, out of convenience and familiarity, used Raspberry Pi for tasks where a microcontrollers would have been perfectly adequate
There was definitely usecase overlap due to the presence of the GPIO, but huge numbers of Pis ended up doing things a microcontroller can't - stuff like the PiHole and Retropie projects, and never used their GPIO pins at all.
Thinking of any of the early Pis as microcontrollers ignores a huge amount of the ways in which actual end users interacted with the thing, and even the way it was sold and marketed. Upton was trying to replace early hacker-friendly home computers like the BBC Micro/Apple II, for a new generation.
> but huge numbers of Pis ended up doing things a microcontroller can't
Mate you know full well it was multiple things... Marketed to education as an actual computer, to the maker demographic as a microcontroller, as a way to learn coding but also robotics etc
>Thinking of any of the early Pis as microcontrollers ignores blah blah blah
This just clarified something for me. I've always been annoyed when I see a Pi with nothing connected to its GPIO header; why not just use a cheap thin client? Or an old laptop, for that matter? But that's missing the point. Here's the point:
Pre-Beagleboard-and-Pi, if you wanted an programmable thing to work with GPIO, you used an Arduino or a BASIC Stamp, or just a plain old PIC. But they wouldn't run a real OS.
Pre-Beagleboard-and-Pi, if you wanted an embedded Linux box, you used a WRT54G or a Soekris or an old laptop. But getting GPIO out of them was a PITA. (And often involved lashing an Arduino to the side.)
The Beagleboard (released in 2008), could finally do both. It had gobs of I/O and first-class support for it under Linux. It was pretty affordable. Then the Raspberry Pi came out in 2012, with a similar amount of GPIO, but demolished the price point to where it made sense to use it in place of a microcontroller.
That's really the magic of the Pi. You can keep one cheap gizmo around, and use it to solve (a large fraction of) two classes of problems. It doesn't fully replace everything a PIC or a PC can do, but it replaces an awful, awful lot of them.
> I've always been annoyed when I see a Pi with nothing connected to its GPIO header; why not just use a cheap thin client?
There have also been times when Pi's were cheap enough and x86 idled so power-inefficiently that you'd save money over a reasonable time horizon if you couldn't run your old laptops at full throttle.
Absurdly extreme example, but at one point I decided to replace a couple (maybe 3) RPi's with a single old Dell rack server off Ebay plus replaced my router with one running pfsense. I knew it would be mostly idle, that thing had 2 Xeon processors to replace 3 cheap ARM processors.
Between the 2 rack servers, my power bill went up by enough to buy a new Pi or two every month. It was like $80/month extra in power bills.
A $2 Chinese ESP32 dev board is more stout in many ways than the first Pentium machine I had, which sure did feel fast-enough to run the whole world with at that time. :)
In this amazing world full of such inexpensive choices, it seems so bizarre to me to demonize any of them. They're all excellent in some way, and it's OK that there's more than one.
This isn't football, handball, American politics, or Highlander: There can be more than one. It's OK.
This is what I keep repeating in many threads about ESP32, the little thing is actually quite powerful, especially for those of us that experienced MS-DOS PCs.
> In the UK, the equivalent tax on housing is council tax
Council tax is difficult to compare to a percentage based property tax - the band based system means people in super valuable homes pay virtually nothing, at least relative to the value of the property, and each of the ~8 bands pays a fixed fee - once in the max band the tax stays the same no matter how valuable the home.
This is especially acute in places like Scotland, where the top band kicks in at anything over 212,000 and hasn't been adjusted since 1991... Essentially any new build starter home in many places will automatically be in the top band and taxed the same as some dude who bought a castle for millions.
Personally I've never thought of council tax as a property tax, even if the bands superficially are linked to it- the link to underlying property values is so broken now.
My first rented flat outta college was taxed at the highest band, and I sure wasn't rich then. It's widely argued to be a very regressive form of taxation - its opponents indeed argue it should be replaced with an actual property tax.
Not sure how widely available this feature is, but the unifi controller software for the popular Ubiquiti APs lets you bind individual client devices to specific APs such that they can only connect to the ones you choose.
I had to solve a similar issue for some crap IoT lights that would join the incorrect AP after a power cut every time.
That works for fixed devices like a TV, but also tends to shrink the effective coverage area of the wireless network as a whole.
That can mean that the portable wifi speaker-widget (which itself doesn't need much bandwidth) might go from working fine on the back deck or well-enough about anywhere else in the yard, to not working at all outside.
> That works for fixed devices like a TV, but also has the effect of shrinking the effective coverage area of the wireless network as a whole.
Which is normally a good thing to push the clients to roam to a better AP, OR you walked out of the building and want you phone to disconnect. But yes, does impact overall coverage area size.
That only works if there's a better AP to roam to. It's often very easy to add more APs indoors; but hanging them outside is a whole different animal.
Meanwhile: As a practical matter, shrinking coverage means "Hey, honey! I fixed the TV!" gets met with a response like "Oh, so that's why I can't listen to Audible on the veranda anymore!" :)
Experimentally probe: say you "fixed" something when you haven't touched anything and see what responses you get.
Obviously only if your honey is the type that enjoys being experimented upon (So long as it isn't mean, I like thoughtful attention like that, but some might not).
> Smalltalk's syntax never go really popular though. One could say that was its biggest drawback.
A lot of Smalltalk-style syntax was absolutely massive for a decade or so you could argue, at least under the guise of the gazillions of iPhone apps that were written in Objective-C. This random blog post probably does a better job than me:
Technically the brushes can wear out, although there are claims they are good for 150,000-250,000 miles it seems.
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