The smartphone represents one of the most significant shifts in our world. In less than thirteen years, we went from some people owning a dumb phone to the majority of the planet having a smartphone (~83.7% as of 2022, according to Statista). There are very few things that a larger percentage of people on this planet have. Not clean water, not housing, not even food.
How does a smartphone work? Most people have no idea; they are insanely complicated devices. However, you can break them down into eight submodules, each of which is merely complex. What makes them work is that each of these components can be made small, at massive economies of scale, and are tightly integrated, allowing easy assembly.
So without further ado, the fundamental eight building blocks of the modern cellphone are: the application processor, the baseband processor, a SIM card, the RF processor, sensors, a display, cameras & lenses, and power management. Let’s have a look at them all, and how they fit together.
While rarely seen by users, the technology behind telephone exchanges is actually quite interesting. In the first hundred or so years of their existence they evolved from manually-operated switchboards to computer-controlled systems, but in between those two stages was a time when dialling and switching was performed electromechanically. This was made possible by the invention of the stepping switch, a type of pulse-operated relay that can connect a single incoming wire to one of many outgoing wires.
Public telephone exchanges contained hundreds of these switches, but as [dearuserhron] shows, it’s possible to make a smaller system with way fewer components: the Cadr-o-station is built around one single stepper switch. Although it looks rather complicated, the only other components are a bunch of ordinary 24 V relays and a few power supplies. Together they make up a minimal telephone exchange that connects up to ten handsets.
It doesn’t have all the functionality of a larger system however, as only a single voice circuit is made to which all phones are automatically connected. Still, it does allow users to dial a number and let the other phone ring, which might be good enough for a home or indeed the hackerspace where it’s currently sitting. It’s also a fine demonstration of how relatively simple technology can be applied to make a surprisingly complex system.
[dearuserhron] wrote an in-depth article on the workings of electromechanical telephone exchanges, which might come in helpful to anyone who’d like to design such a system for their own home. For a more general introduction into analog phone technology, check out our analysis of a 1970s rotary telephone.
While gliding might be the most calm and peaceful way of moving through the air, launching a glider is a rather noisy and violent process. Although electric winches do exist, most airfields use big V8-powered machines to get their gliders airborne. [Peter Turczak] noticed that the winch operators at his airfield often had to juggle multiple communication channels while pressing buttons and moving levers, all with the deafening roar of a combustion engine right next to them. To make their life easier, he built a single communication device that combines multiple radio inputs and an analog telephone .
The main user interface is a sturdy headset that dampens engine noise significantly. This headset is connected to a cabinet that contains several modules connecting to different audio sources: an analog telephone line, an aircraft radio receiver, a PMR handheld radio, and even a music source in case the other lines are quiet. The system contains automatic switchover circuits based on a priority system, ensuring that important messages are never missed.
The electronic design is based on classic analog components like NE5532 and TL084 op amps, all mounted on small, custom-made PCBs. Audio transformers are used to avoid ground loops between the various signal sources while relays mute sources that are not prioritized. To ensure seamless compatibility with the telephone network, [Peter] used components from old desk phones, including line transformers, a DTMF keypad and even a mechanical ringer. His blog post is full of details that will be of interest to anyone working with op amps and audio, such as how to stabilize an amplifier that has significant wiring capacitance on its input.
At heart this whole project is “just” an audio mixer, although optimized for a very specific purpose. But designing even a simple mixer is by no means an easy task, as we reported a few years back. If you’re more into winches, you’ll be delighted to find that smaller ones can also be used for sledding and even wakeboarding.
One of the brave but unsuccessful plays from Nokia during their glory years was the N-Gage, an attempt to merge a Symbian smartphone and a handheld game console. It may not have managed to dethrone the Game Boy Advance but it still has a band of enthusiasts, and among them is [Michael Fitzmayer] who has produced a CMake-based toolchain for the original Symbian SDK. This is intended to ease development on the devices by making them more accessible to the tools of the 2020s, and may serve to bring a new generation of applications to those old Nokias still lying forgotten in dusty drawers.
In much of the public imagination, the invention of the smartphone came with the release of the first Apple iPhone in 2007. Hackaday readers will of course trace the smartphone back much further than that to an original IBM prototype, and will remind any doubters that the Nokias which the iPhone vanquished were very successful smartphones without any of Cupertino’s magic in sight. Nokia’s tragedy was that they appeared not to understand what they had in Symbian, and released a bewildering array of devices intended to satisfy every possible market without recognizing that the market they needed to serve was their customers being easily able to run the apps of their choice on the things.
Symbian itself has long ago become a piece of abandonware, but during its chequered history there was a period in which an open-source version was released. It would be nice to think that projects such as this one might revive interest in this capable yet forgotten operating system, as with the passage of a decade the cost of hardware which might run it has fallen to the point of affordability. Does anyone want to relive the 2000s?
The pulse-dial telephone and its associated mechanical exchange represents the pinnacle of late-19th and early-20th century electromechanical technology, but its vestiges have disappeared from view with astonishing rapidity. [Matthew Harrold] is a telecoms enthusiast who’s been kind enough to share with us the teardown and refurbishment of that most signature of pulse-dial components, a telephone dial. In this case it’s on a rather unusual instrument, a British GPO outdoor phone that would have been seen in all kinds of industrial and safety installations back in the day and can probably still be found in the wild today if you know where to look.
The teardown soon identifies a dial that runs very slowly and is sorely in need of a clean. There follows a detailed part-by-part dismantling of the dial mechanism, followed by a careful clean, polish, and reassembly. He notes that a previous owner had used grease to lubricate it, probably the reason for its slow operation.
If you thought programming your 1990s VCR was rough, wait until you see this Russian telephone autodialer that [Mike] took apart over on the mikeselectricalstuff YouTube channel (video below the break). [Mike] got this 1980s Soviet-era machine a few years ago, and finally got around to breaking into it to learning what makes it tick. The autodialer plugs into the phone line, much like an old-school answering machine. It provides the user with 40 pre-set telephone numbers, arranged in two banks of 20, and a speaker to monitor the connection process. It uses pulse dialing — no touch tones. What’s surprising is how you program the numbers. Given that this was build in the 1980s Soviet Union, he wasn’t expecting a microcontroller. But he wasn’t expecting transformer core “rope” memory, either.
The phone normally sits on a platform on the left side of the machine. Raising up the platform exposes a bank of toroidal cores, arranged in seven rows of four. Each row corresponds to a dialed digit, and the four cores used to encode a single digit. At the top and bottom of the programming board are two 40-pin connectors, each pin corresponding to one of the preset phone numbers. A bunch of patch wires would have been provided, and you program each number by threading a long wire through the appropriate cores, connecting it at the top and bottom connectors much like a modern solderless breadboard. It’s also interesting to see the components and construction technique of this circuit board. For example, the diodes have the strip on the Anode end, not the cathode as we’re normally used to today. The transistor cans are mounted upside down like dead spiders.
On December 5th, someone by the IRC nickname of [ubuntu] joined the Pine64 Discord’s #pinephone channel through an IRC bridge. In the spirit of December gift-giving traditions, they have presented their fellow PinePhone users with an offering – a “Snake” game. What [ubuntu] supposedly designed had the potential to become a stock, out-of-the-box-installed application with a small but dedicated community of fans, modders and speedrunners.
Unfortunately, that would not be the alternate universe we live in, and all was not well with the package being shared along with a cheerful “hei gaiz I make snake gaem here is link www2-pinephnoe-games-com-tz replace dash with dot kthxbai” announcement. Shockingly, it was a trojan! Beneath layers of Base64 and Bashfuscator we’d encounter shell code that could be in the “example usage” section of a modern-day thesaurus entry for the word “yeet“.