The plethora of smart home devices available today deliver all manner of opportunities, but it’s fair to say that interfacing with them is more often done in the browser or an app than in the terminal. WattWise from [Naveen Kulandaivelu] is a tool which changes all that, it’s a command-line interface (CLI) for power monitoring smart plugs.

Written in Python, the tool can talk either directly to TP-Link branded smart plugs, or via Home Assistant. It tracks the power consumption with a simple graph, but the exciting part lies in how it can be used to throttle the CPU of a computer in order to use power at the points in the day when it is cheapest. You can find the code in a GitHub repository.

We like the idea of using smart plugs as instruments, even if they may not be the most accurate of measurement tools. It takes them even further beyond the simple functionality and walled-garden interfaces provided by their manufacturers, which in our view can only be a good thing.

Meanwhile, for further reading we’ve looked at smart plugs in detail in the past.

Early photography lacked the convenience of the stable roll film we all know, and instead relied on a set of processes which the photographer would have to master from film to final print. Photographic chemicals could be flammable or even deadly, and results took a huge amount of work.

The daguerreotype process of using mercury to develop pictures on polished metal, and the wet-collodion plate with its nitrocellulose solution are well-known, but as conservators at the British National Archives found out, there was another process that’s much rarer. The Pannotype uses a collodion emulsion, but instead of the glass plate used by the wet-plate process it uses a fabric backing.

We know so much about the other processes because they were subject to patents, but pannotype never had a patent due to a disagreement. Thus when the conservators encountered some pannotypes in varying states of preservation, they needed to apply modern analytical techniques to understand the chemistry and select the best methods of stabilization. The linked article details those analyses, and provides them with some pointers towards conserving their collection. We look forward to someone making pannotype prints here in 2025, after all it’s not the first recreation of early photography we’ve seen.

Prototyping is a personal affair, with approaches ranging from dead-bug parts on tinplate through stripboard and protoboard, to solderless breadboards and more. Whichever you prefer, a common problem is that they don’t offer much in the way of solid connections to the outside world. You could use break-out boards, or you could do like [Pakequis] and make a prototyping board with every connector you can think of ready to go.

The board features the expected prototyping space in the middle, and we weren’t joking when we said every connector. There are analogue, serial, USB, headers aplenty, footprints for microcontroller boards, an Arduino shield, a Raspberry Pi header, and much more. There will doubtless be ones that readers will spot as missing, but it’s a pretty good selection.

We can imagine that with a solderless breadboard stuck in the middle it could be a very useful aid for teaching electronics, and we think it would give more than a few commercial boards a run for their money. It’s not the first we’ve featured, either.

We use ARM devices in everything from our microcontroller projects to our laptops, and many of us are aware of the architecture’s humble beginnings in a 1980s Acorn Archimedes computer. ARM processors are not the only survivor from the Archimedes though, its operating system has made it through the decades as well.

RISC OS is a general purpose desktop operating system for ARM platforms that remains useful in 2025, as well as extremely accessible due to a Raspberry Pi port. No software can stand still though, and if RISC OS is to remain relevant it must move with the times. Thus RISC OS Open, the company behind its development, have launched what they call a Moonshots Initiative, moving the OS away from incremental development towards much bolder steps. This is necessary in order for it to support the next generation of ARM architectures.

We like RISC OS here at Hackaday and have kept up to date with its recent developments, but even we as fans can see that it is in part a little dated. From the point of view of RISC OS Open though, they identify support for 64-bit platforms as their highest priority, and to that end they’re looking for developers, funding partners, and community advocates. If that’s you, get in touch with them!

Music consumption has followed a trend over the last decade or more of abandoning physical media for online or streaming alternatives. This can present a problem for young children however, for whom a simpler physical interface may be an easier way to play those tunes. Maintaining a library of CDs is not entirely convenient either, so [JakesMD] has created the Yaydio. It’s a music player for kids, that plays music when a card is inserted in its slot.

As you might expect, the cards themselves do not contain the music. Instead they are NFC cards, and the player starts the corresponding album from its SD card when one is detected. The hardware is simple enough, an Arduino Nano with modules for MP3 playback, NFC reading, seven segment display, and rotary encoder. The whole thing lives in a kid-friendly 3D printed case.

Some thought has been given to easily adding albums and assigning cards to them, making it easy to keep up with the youngster’s tastes. This isn’t the first such kid-friendly music player we’ve seen, but it’s certainly pretty neat.

The Pomdoro technique of time management has moved on a little from the tomato-shaped kitchen timer which gave it a name, as [Rukenshia] shows us with this nifty ESP32 and e-paper design. It’s relatively simple in hardware terms, being a collection of off-the-shelf modules in a 3D printed case, but the software has a custom interface for the friend it was built for.

At its heart is a NodeMCU board and a Waveshare display module, with a rotary encoder and addressable LED as further interface components. A lot of attention has been paid to the different options for the interface, and to make the front end displayed on the screen as friendly and useful as possible. Power comes via USB-C, something that should be available in most working environments here in 2025.

We’ve tried a variant on this technique for a while now with varying success, maybe because a mobile phone doesn’t make for as good a timer as a dedicated piece of hardware such as this. Perhaps we should follow this example. If we did, the Hackaday timer couldn’t possibly use an ESP32.

The sun is our planet’s source of natural illumination, and though we’ve mastered making artificial light sources, it remains extremely difficult to copy our nearby star. As if matching the intensity wasn’t enough, its spectral quality, collimation, and atmospheric scattering make it an special challenge. [Victor Poughon] has given it a go though, using a bank of LEDs and an interesting lens system.

We’re used to lenses being something that can be bought off-the-shelf, but this design eschews that convenience by having the lenses manufactured and polished as an array, by JLC. The scattering is taken care of by a sheet of inkjet printer film, and the LEDs are mounted on a set of custom PCBs.

The result is certainly a very bright light, and one whose collimation delivers a sun-like effect of coming from a great distance. It may not be as bright as the real thing, but it’s certainly something close. If you’d like something to compare it to, it’s not the first such light we’ve featured.

Scanning a film negative is as simple as holding it up against a light source and photographing the result. But should you try such a straightforward method with color negatives it’s possible your results may leave a little to be desired. White LEDs have a spectrum which looks white to our eyes, but which doesn’t quite match that of the photographic emulsions.

[JackW01] is here with a negative scanning light that uses instead a trio of red, green, and blue LEDs whose wavelengths have been chosen for that crucial match. With it, it’s possible to make a good quality scan with far less post-processing.

The light itself uses 665 nm for red, 525 nm for green, and 450 nm blue diodes mounted in a grid behind a carefully designed diffuser. The write-up goes into great detail about the spectra in question, showing the shortcomings of the various alternatives.

We can immediately see the value here at Hackaday, because like many a photographer working with analogue and digital media, we’ve grappled with color matching ourselves.

This isn’t the first time we’ve considered film scanning but it may be the first project we’ve seen go into such detail with the light source. We have looked at the resolution of the film though.

Toaster oven reflow projects are such a done deal that there should be nothing new in one here in 2025. Take a toaster oven, an Arduino, and a thermocouple, and bake those boards! But [Paul J R] has found a new take on an old project, and better still, he’s found the most diminutive of toaster ovens from the Australian version of Kmart. We love the project for the tiny oven alone.

The brains of the operation is an ESP32, in the form of either a TTGO TTDisplay board or an S3-Zero board on a custom carrier PCB, with a thermistor rather than a thermocouple for the temperature sensing, and a solid state relay to control mains power for the heater. All the resources are in a GitHub repository, but you may have to make do with a more conventionally-sized table top toaster oven if you’re not an Aussie.

If you’re interested, but want a better controller board, we’ve got you covered.

The cartridge based game consoles of decades ago had a relatively simple modus operandi — they would run a program stored in a ROM in the cartridge, and on the screen would be the game for the enjoyment of the owner. This made them simple in hardware terms, but for hackers in the 2020s, somewhat inflexible. The Atari 2600 is particularly troublesome in this respect, with its clever use of limited hardware making it not the easiest to program at the best of times. This makes [Nick Bild]’s Atari 2600 photo frame project particularly impressive.

The 2600 has such limited graphics hardware that there’s no handy frame buffer to place image data into, instead there are some clever tricks evolved over years by the community to build up bitmap images using sprites. Only 64 by 84 pixels are possible, but for mid-70s consumer hardware this is quite the achievement.

In the case of this cartridge the ROM is replaced by a Raspberry Pi Pico, which does the job of both supplying the small Atari 2600 program to display the images, and feeding the image data in a form pre-processed for the Atari.

The result is very 8-bit in its aesthetic and barely what you might refer to as photos at all, but on the other hand making the Atari do this at all is something of a feat. Everything can be found in a GitHub repository.

If new hardware making an old console perform unexpected tricks is your bag, we definitely have more for you.

Many of us could have been lucky enough to have some form of pedal go-kart in our formative years, and among such lucky children there can have been few who did not wish for their ride to have a little power. Zipping around the neighborhood remained a strenuous affair though, particularly for anyone whose hometown was on a hill. What a shame we didn’t have [Matto Godoy] as a dad then, because he has taken a child’s go-kart and turned it into the electrically-propelled ride of dreams.

Out come the pedals and in goes a wooden floor panel, and at the rear the axle is replaced by a set of hoverboard motors and associated batteries and controllers. The wheels are off-the-shelf wheelbarrow parts, and the 36 V lithium-polymer gives it plenty of go. It looks too small for us, but yes! We want one.

If you want one too, you could do worse than considering a Hacky Racer. And if more motor power is your thing, raid the auto recyclers!

The Vectrex console from the early 1980s holds a special place in retrocomputing lore thanks to its vector display — uniquely for a home system, it painted its graphics to the screen by drawing them with an electron beam, instead of scanning across a raster as a TV screen would. It thus came with its own CRT, and a distinctive vertical screen form factor.

For all that though, it was just a games console, but there were rumors that it might have become more. [Intric8] embarked on a quest to find some evidence, and eventually turned up what little remains in a copy of Electronic Games magazine. A keyboard, RAM and ROM expansion, and a wafer drive were in the works, which would have made the Vectrex a quirky equal of most of what the likes of Commodore and Sinclair had to offer.

It’s annoying that it doesn’t specify which issue of the magazine has the piece, and after a bit or browsing archive.org we’re sorry to say we can’t find it ourselves. But the piece itself bears a second look, for what it tells us about the febrile world of the 8-bit games industry. This was a time of intense competition in the period around the great console crash, and developers would claim anything to secure a few column inches in a magazine. It’s not to say that the people behind the Vectrex wouldn’t have produced a home computer add-on for it if they could have done, but we remember as teenagers being suckered in by too many of these stories. We still kinda want one, but we’d be surprised if any ever existed.

If you have a Vectrex, it’s possible to give it a light pen.

A decade ago, smartwatches were an unexplored avenue full of exotic promise. There were bleeding-edge and eye-wateringly expensive platforms from the likes of Samsung or Apple, but for the more experimental among technophiles there was the Pebble. Based on a microcontroller and with a relatively low-resolution display, it was the subject of a successful crowdfunding campaign and became quite the thing to have. Now long gone, it has survived in open-source form, and now if you’re a Pebble die-hard you can even buy a new Pebble. We’re not sure about their choice of name though, we think calling something the “Core 2 Duo” might attract the attention of Intel’s lawyers.

The idea is broadly the same as the original, and remains compatible with software from back in the day. New are some extra sensors, longer battery life, and an nRF52840 BLE microcontroller running the show. It certainly captures the original well, however we’re left wondering whether a 2013 experience still cuts it in 2025 at that price. We suspect in that vein it would be the ideal compliment to your game controller when playing Grand Theft Auto V, another evergreen 2013 hit.

We look forward to seeing where this goes, and we reported on the OS becoming open source earlier this year. Perhaps someone might produce a piece of open source hardware to do the same job?

For those of us lucky enough to have been at Hackaday Europe in Berlin, there was a feast of hacks at our disposal. Among them was [Vladimir Divic]’s gradients game, software for an M5Stack module which was definitely a lot of fun to play. The idea of the game is simple enough, a procedurally generated contour map is displayed on the screen, and the player must navigate a red ball around and collect as many green ones as possible. It’s navigated using the M5Stack’s accelerometer, which is what makes for the engaging gameplay. In particular it takes a moment to discover that the ball can be given momentum, making it something more than a simple case of ball-rolling.

Underneath the hood it’s an Arduino .ino  file for the M5Stack’s ESP32, and thus shouldn’t present a particular challenge to most readers. Meanwhile the M5Stack with its versatile range of peripherals has made it onto these pages several times over the years, not least as a LoRA gateway.

Shell scripting is an often forgotten programming environment, relegated to simple automation tasks and little else. In fact, it’s possible to achieve much more complex tasks in the shell. As an example, here’s [calebccf] with an emulated 6502 system in a busybox ash shell script.

What’s in the emulator? A simple 6502 system with RAM, ROM, and an emulated serial port on STDIO. It comes with the wozmon Apple 1 monitor and BASIC, making for a very mid-1970s experience. There’s even a built-in monitor and debugger, which from our memories of debugging hand-assembled 8-bit code back in the day, should be extremely useful.

Although the default machine has a generous 32k of RAM and 16k ROM, you can easily adjust these limits by editing machine.sh. In addition, you can get a log of execution via a socket if you like. Don’t expect it to run too fast, and we did have to adjust the #! line to get it to run on our system (we pointed it to bash, but your results may vary).

What you use this for is up to you, but we’re sure you’ll all agree it’s an impressive feat in the shell. It’s not the first time we’ve seen some impressive feats there, though. Our Linux Fu column does a lot with the shell if you want further inspiration.

With inexpensive microntrollers capable of the most impressive feats of sound synthesis, it’s not so often we see projects that return to an earlier style of electronic music project. The 1-bit synth from [Electroagenda] takes us firmly into that territory, employing that most trusty of circuits, a 555.

It’s a time-honored circuit, a 555 provides a note clock that drives a 4017 that functions as a sequencer. This switches in a set of voltage dividers, which in turn control another 555 oscillator that produces the notes. It’s a fun toy straight from the 1970s, right down to the protoboard and hookup wire construction. There’s a demo video with some lovely beeps below, and we think most of you should have what it takes to make your own.

If you’re seeking more inspiration, may we introduce you to our Logic Noise series?

One of those useful things to have around on your bench is a decade resistance box, essentially a dial-a-resistance instrument. They used to be quite expensive in line with the cost of close-tolerance resistors, but the prices have come down and it’s within reach to build your own. Electronic design consultancy Dekimo have a nice design for one made from a series of PCBs which they normally give out at trade fairs, but now they’ve released the files for download.

It’s released as Gerbers and BOM with a pick-and-place file only, and there’s no licence so it’s free-as-in-beer, but that should be enough if you fancy a go. Our Gerber viewer is playing up so we’re not entirely sure how reliable using PCBs as wafer switches will be long-term, but since the pictures are all ENIG boards we’d guess the gold plating will be much better than the HASL on all those cheap multimeters.

We like this as a conference giveaway, being used to badges it’s refreshing to see a passive take on a PCB artwork. Meanwhile this isn’t the first resistance box we’ve seen with unconventional switches.

We have all seen optimistic claims for electronic products that fail to match the reality, and [Electronic Wizard] is following one up in a recent video. Can a relatively small IGBT really switch 200 A as claimed by a dubious seller? Off to the datasheet to find out!

The device in question is from Toshiba, and comes in a TO-220 package. This itself makes us pause for a minute, because we suspect the pins on a TO220 would act more like fuses at a steady 200 A.

But in the datasheet, there it is: 200 A. Which would be great, but of course it turns out that this is the instantaneous maximum current for a few microsecond pulse. Even then it’s not finished, because while the continuous current is supposed to he half that, in the datasheet it specifies a junction temperature of 25 °C. The cooling rig required to maintain that with this transistor passing 200 A would we think be a sight to behold, so for all intents and purposes this can’t even switch a continuous 100 A. And the real figure is much less as you’d imagine, but it raises an important point. We blindly read datasheets and trust them, but sometimes we should engage brain before releasing the magic smoke.

We’re used to low cost parts and a diversity of electronic functions to choose from in our projects, to the extent that our antecedents would be green with envy. Back when tubes were king, electronics was a much more expensive pursuit with new parts, so designers had to be much more clever in their work. [Thomas Scherrer OZ2CPU] has just such a design on his bench, it’s a Heathkit Capaci-Tester designed in 1959, and we love it for the clever tricks it uses.

It’s typical of Heathkits of this era, with a sturdy chassis and components mounted on tag strips. As the name suggests, it’s a capacitor tester, and it uses a magic eye tube as its display. It’s looking for short circuits, open circuits, and low equivalent resistance, and it achieves this by looking at the loading the device under test places on a 19 MHz oscillator. But here comes that economy of parts; there’s no rectifier so the circuit runs on an AC HT voltage from a transformer, and that magic eye tube performs the task of oscillator as well as display.

He finds it to be in good condition in the video below the break, though he removes a capacitor placed from one of the mains input lines to chassis. It runs, and confirms his test capacitor is still good. It can’t measure the capacitance, but we’re guessing the resourceful engineer would also have constructed a bridge for that.