Reusing An Old Android Phone For GPIO With External USB Devices

November 4, 2024 by Maya Posch 44 Comments

Each year millions of old smartphones are either tossed as e-waste or are condemned to lie unloved in dusty drawers, despite the hardware in them usually being still perfectly fine. Reusing these little computers for another purpose once the phone’s manufacturer drops support is made hard by a range of hardware and software (driver) issues. One possible way to do so is suggested by [Doctor Volt] in a video where a Samsung Galaxy S4 is combined with a USB-connected FT232R board to add external GPIO.

The idea is pretty simple: the serial adapter is recognized by the existing Android OS and within the standard Android development environment this module can be used. Within this demonstrator it’s merely used to blink some LEDs and react to inputs, but it shows how to reuse one of these phones in a non-destructive manner. Even better is that the phone’s existing sensors and cameras can still be used as normal in this way, too, which opens a whole range of (cheap) DIY projects that can be programmed either in Java/Kotlin or in C or C++ via the Native Development Kit.

The only wrinkle is that while the phone is connected like this, charging is not possible. For the S4 it’s easy to solve as it has a removable battery, so an external power input was wired in with a dummy battery-sized bit of perfboard. With modern phones without removable batteries simultaneous USB/audio dongle and charging usage via the USB-C connector is claimed to be possible, but this is something to check beforehand.

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CCFL Scanner Bulb Makes A Cool Desk Lamp

August 31, 2024 by Alexander Rowsell 12 Comments

The bulbs inside scanners (before transitioning to LED, anyway) were cold cathode fluorescent tubes that emit a fairly wide bandwidth of light. They were purpose-built to produce a very specific type and shape of light, but [Julius Curt] has taken this in a new, upcycled direction. Instead of just producing light, the light itself is also part of the aesthetic. A very cool 3D printed case houses the bulb and power supply and smartly hides the connecting wires to achieve a very clean look.

Part of the design involves adding a DC-DC converter before the lamp driver, allowing fading of the light. This isn’t anything new in lamps, but [Julius] noticed an interesting effect when dimming the vertically oriented lamp: as the power was reduced, the column of light would start to extinguish from one end, leading to an elongated teardrop-shaped light source.

This leads to a very interesting look, and the neat case design leads to an extremely unique lamp! The emitted light’s color temperature seems to vary a bit as the voltage drops, going from what appears to be a pretty cold white to a slightly warmer tone.

The design process is detailed on the project page, with a quick look at the CAD design process for the case. A neat touch was using a greeble (part of a coffee grinder) to add some different textures and break up the plastic-only look. That’s one we’ll have to note in our design books!

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PostmarketOS Now Boots On Over 250 Devices

June 17, 2024 by Tom Nardi 42 Comments

Every year, as consumers gobble up the latest Android devices, more old, but perfectly serviceable, units end up collecting dust in drawers. Or worse, they end up getting tossed in the trash. One of the most promising tools we have to help keep these older devices useful is postmarketOS, a full-fledged Linux distribution that provides a flexible and up-to-date software environment on devices that might otherwise be stuck with some old and unsupported version of Google’s mobile operating system.

As of the latest update on the postmarketOS blog, the team has announced an exciting milestone: over 250 devices can now boot the stable release of the OS.

Now to be clear, not all devices will be fully functional. In fact, the blog post clarifies that some of them only barely boot. But it’s progress, and now that these semi-supported devices aren’t hidden behind a development version of the OS, it means more folks will be able to put them to use.

For example, if you want to turn your old smartphone into a low-energy headless webserver, it doesn’t really matter if its display, touchscreen, or speakers are supported. You just need it to boot into Linux and fire up an SSH server so you can get in and start working.

But support for new devices is just one of the additions in this new v24.06 release. The blog post also points out several notable software upgrades, including the move to the 6.x branch of KDE Plasma Mobile. This brings with it a long list of improvements and changes, including a rewritten homescreen with enhanced customization options. If you prefer a more minimal GUI, don’t worry. This new release also updates Sxmo, which provides a menu-driven interface for both touch screens and hardware controls.

Among the newly supported devices is a generic x86_64 image that should work on a wide array of PCs. While obviously there’s no shortage of Linux distros you could run on your old computer, being able to install postmarketOS on it is definitely helpful for development purposes. There’s also a new Tegra ARMv7 target which brings a number of new devices into the fold, such as the Google Nexus 7, and Microsoft Surface RT.

Looking to run postmarketOS on your own hardware? The best way to start is to check the Devices page and see how many of those old gadgets you’ve got collecting dust in a drawer are compatible.

Repurposing Old Smartphones: When Reusing Makes More Sense Than Recycling

February 28, 2023 by Maya Posch 89 Comments

When looking at the specifications of smartphones that have been released over the past years, it’s remarkable to see how aspects like CPU cores, clockspeeds and GPU performance have improved during this time, with even new budget smartphones offering a lot of computing power, as well as a smattering of sensors. Perhaps even more remarkable is that of the approximately 1.5 billion smartphones sold each year, many will be discarded again after a mere two years of use. This seems rather wasteful, and a recent paper by Jennifer Switzer and colleagues proposes that a so-called Computational Carbon Intensity (CCI) metric should be used to determine when it makes more sense to recycle a device than to keep using it.

What complicates the decision of when it makes more sense to reuse than recycle is that there are many ways to define when a device is no longer ‘fit for purpose’. It could be argued that the average smartphone is still more than good enough after two years to be continued as a smartphone for another few years at least, or at least until the manufacturer stops supplying updates. Beyond the use as a smartphone, they’re still devices with a screen, WiFi connection and a capable processor, which should make it suitable for a myriad of roles.

Unfortunately, as we have seen with the disaster that was Samsung’s ‘upcycling’ concept a few years ago, or Google’s defunct Project Ara, as promising as the whole idea of ‘reuse, upcycle, recycle’ sounds, establishing an industry standard here is frustratingly complicated. Worse, over the years smartphones have become ever more sealed-up, glued-together devices that complicate the ‘reuse’ narrative.

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Sketch of a Tandy TRS-80 Model 100 with Arduino Mega 2560

TRS-80 Model 100 Gets Arduino Heart Transplant

September 23, 2022 by Dave Walker 4 Comments

When [Stephen Cass] found himself with a broken Tandy TRS-80 Model 100 portable computer, the simplest solution was to buy another broken one and make one working computer from two non-working computers. However, this left him with a dilemma — what to do with the (now even more) broken one left over?

LCD layout is unusual by modern standard, but optimized for fast updates

Naturally, he did what a lot of us would do and used modern hardware to interface with the original parts that still work. In this case it meant replacing the motherboard with an Arduino Mega 2560.

Luckily, the Model 100 has a substantial fanbase and there’s a lot of helpful information available online, including the detailed service manual, that helped [Stephen] to understand how to drive the unusual display. The LCD has a resolution of 240×64 pixels, which are broken down into eight zones of 50×32 pixels, and two zones of 40×42 pixels. Each zone is then further divided into four banks, eight pixels tall, so that each column of eight pixels corresponds to a single byte.

Every one of the ten zones is controlled by an individual HD44102 driver IC, connected to a 30-bit wide bus for selecting the correct chip, bank and column.

With the Arduino handling the data, the old LCD still needed a -5 V supply for contrast and an RC filter to smooth out the PWM signal [Stephen] is using to adjust the viewing angle.

With the new interface, [Stephen] is able to access all of the pixels on the original display, and to use modern graphics libraries such as displayio. With the display issue solved, he intends to use a separate Teensy 4.1 to connect with the keyboard matrix and provide a VT100 terminal interface.

Upcycling old, broken hardware can be a lot of fun and is always educational. Understanding why certain design decisions were made at a time when the engineering trade-offs were different can lead to insights that are directly relevant to modern designs when resources get tight. In this case, the quirky LCD drivers were a response to making the display of text as efficient as possible, so as not to overburden the processor.

The TRS-80 computers are ripe for hacking, with their “built-for-service” designs, and we’ve featured a few in the past. Some have replaced the motherboard with something newer, like [Stephen], whereas others have also replaced the display, or connected them to the cellphone network.

Have you found new ways to get old hardware working? Tell us in the comments below or send us a message on the Hackaday tips line.

Thanks to [nb0x0308] for the tip!

Finished pipe crimper made from recycled parts

Making A Pipe Crimper From Scrap

August 30, 2022 by Dave Rowntree 19 Comments

We love upcycling around these parts — taking what would be a pile of rusty scrap and turning it into something useful — and this project from YouTuber [Hands on Table] is no different. Starting with a pair of solid looking sprockets, one big, one small, and some matching chain, a few lumps of roughly hewn steel plate were machined to form some additional parts. A concentric (rear mounted) plate was temporarily welded to the sprocket so matching radial slots could be milled, before it was removed. Next, the sprocket was machined on the inside to add a smooth edge for the crimping fingers (is that the correct term? We’re going with it!) to engage with.

These fingers started life as an off the shelf 3/8″ HSS tool bit, ground down by hand, to produce the desired crimping profile. A small piece of steel was welded on to each, to allow a small spring to act on the finger, enabling it to retract at the end of the crimping action. We did spot the steel plate being held in place with a small magnet, prior to welding. The heat from that would likely kill off the magnetic field in a short space of time, but they’re so cheap as to be disposable items anyway.

A small ring rides on top of the assembly, bolted to the fixed rear plate. The prevents the crimping fingers from falling out . The fingers are constrained by the slots in the rear plate, so the result is that they can only move radially. As the big sprocket is rotated, they get progressively pushed towards the center, giving that nice, even crimping action. Extra mechanical advantage is provided by driving the small sprocket with a wrench. Super simple stuff, and by the looks of the device in action, pretty effective at crimping the hose fittings it was intended for.

Taking one thing and turning it into something else may well be the very essence of hacking. We’ve seen many hacky upcycling efforts, such as this bench disk sander built from a dryer machine motor. Of course, upcycling is not limited to machines, tools and electronic doodads. Here a trapper hat made out of an old skirt. And why not?

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A Tuning Fork Clock, With Discrete Logic

February 8, 2022 by Dave Rowntree 8 Comments

[Willem Koopman aka Secretbatcave] was looking at a master clock he has in his collection which was quite a noisy device, but wanted to use the matching solenoid slave clock mechanism he had to hand. Willem is a fan of old-school ‘sector’ clocks, so proceeded to build his ideal time piece — Vibrmatic — exactly the way he wanted. Now, since most time keeping devices utilise a crystal oscillator — which is little more than a lump of vibrating quartz — why not scale it up a bit and use the same principle, except with a metal tuning fork? (some profanity, just to warn you!)

A crystal oscillator operates in a simple manner; you put some electrical energy in, it resonates at its natural frequency, you sense that resonance, and feed it back into it to keep it sustaining. With a tuning fork oscillator, the vibration forcing and the feedback are both done via induction, coils act as the bridge between the electronic and mechanical worlds.

By mounting the tuning fork onto a shock mounting, the 257 Hz drone was kept from leaking out into the case and disturbing the household. This fork was specified to be 256 Hz, but [Willem] reckons the drag of the electromagnets pushed it off frequency a bit. Which make sense, since its a mechanical system, that has extra forces acting upon it.

The sector face was CNC cut from aluminium, the graphics engraved, then polished up a bit. Finally after a spot of paint, it looks pretty smart. Some nice chunks of upcycled wood taken from some building work spoils formed the exposed enclosure. On the electronics side, after totally ignoring the frequency error, and then tripping over a bunch of problems such as harmonics in the oscillation, and an incorrectly set-up divider, a solution which seemed to work was found, but like always, there are quite a few more details to the story to be found in the build log.

We’ve seen a tuning fork clock recently, like this 440 Hz device by [Kris Slyka] that the project above references, and whilst we’re talking about tuning forks, here’s a project log showing the insides of those ubiquitous 32.768 kHz crystal units.