Over the last decade or so, we’ve been inundated with appliances with wireless or “smart” technology that is often of dubious utility. No one really needs a tablet in their refrigerator or Wi-Fi on their coffee maker. A less glamorous kitchen appliance that actually might benefit from some automation and connectivity is the garbage can, or “bin” for those speaking the Queen’s English, and [Mellow_Labs] is here to show off just how to get that done with this automatic garbage can lid.

As he explains, the real impetus behind this build is to not have to touch a dirty lid while cooking to avoid having to take time to wash one’s hands again afterwards. There are a few other design criteria as well; it has to be roommate-approved so nothing permanently attached to the lid, overly complicated, or with an unnecessary amount of wires or other fixtures. A servo with an extension sits on the lid itself, and when activated forces the lid open. A distance sensor provides basic gesture recognition and a microcontroller with wireless connectivity controls both and provides home automation integration as well. With a 3D printed case that includes a quick disconnect function for easy cleaning of the lid, the build was ready to be put into service.

The first iteration used an infrared distance sensor, but placing it by an open window caused it to continuously open and close since sunlight has the same wavelengths of light the sensor is tuned for. A quick swap with an ultrasonic sensor solved the problem, and the garbage can is working flawlessly in the kitchen now. Another appliance that is generally not targeted by off-the-shelf automation solutions is the range fume hood, but another build tackled that problem a while back.

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What lies at the heart of many games? In a sense, it’s your response time, which is a function of hand-eye coordination. Although the 2024 Business Card Challenge has come to a close, [gokux] tends to go small anyway, and has taken their miniature approach to the Tiny Games Challenge with this awesome little reaction time game.

It’s basically whack-a-mole, but instead of striking down fuzzy puppets, you get fast and furious on big buttons that light up. Press any button to start, and there is a 3-2-1 countdown to get you geared up for action. Once the screen says ‘GO’, you’re off to the races. Each of the four buttons will light up in random order, and your overall response time is taken as the average of these four.

While there are many microcontrollers that would work here, [gokux] chose the Seeed Studio Xiao ESP32-C3. If you want to make one of these for yourself, there are excellent build instructions waiting for you. Be sure to check it out in action after the break. Oh, and be sure to let [gokux] know if you can beat 220 ms.

So, [zyumbik]’s trademark seems to be sexing things up, and the Artsey layout did not escape their gaze. This is the Sexy Artsey. Let’s back up a bit.

Image by [zyumbik] via redditArtsey is a keyboard layout for chording, and this keyboard is built for it. It’s a one-handed keyboard meant for pressing multiple keys at a time to produce each character. With some use, [zyumbik] discovered that the Taipo layout might be a better fit, so there are currently some elements of both.

If you’d like to make this adorable keyboard, everything is waiting for you to download, including files for various thingamabobs you can stick on the side there where the rainbow is now. There’s also a groovy flower version of the knob.

Controller-wise, you can use a Seeed Studio Xiao in either BLE or RP2040 format, or the Waveshare RP2040 Zero. The firmware is written in ZMK.

Remember the death metal macropad? (Who could forget that tentacled nightmare?) This is the same creator. Kind of hard to believe, innit? Well, except for the spikes. Apparently they’re for thumb discipline.

Via reddit

Oooh, Dream Keyboard: I Believe You Can Get Me Through My Life

Perhaps the YouTube algorithm fed you this one the other day, too. As an iOS developer, [Christian Selig] spends all day typing, and has owned a lot of keyboards as a result. Like, a lot of keyboards. But, as you may have guessed, none of them fully satisfy.

Image via YouTubeAnd so began the familiar hero’s journey of building something new, something perfect for them. A dream keyboard. Maybe it’ll be your dream keyboard, too.

[Christian] hid the nice!nano underneath the keyboard to make it as sleek as possible, almost as though Apple themselves designed an ortho split.

Of particular note here is that [Christian] used a nifty program called Ergogen to generate the both the PCB layout and the 3D-printable case with just a few lines of very readable “code”. Even so, [Christian] still got to play connect-the-dots in KiCad.

This is a great video all around. It’s low-level enough to be interesting to those who have already built a keyboard, but high-level enough to draw in new people who might just catch the bug.

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Thanks to [Joey] and [foamyguy] for the tip!

The Centerfold: Keycap World Map

Image by [mathinpenn] via redditGuess the number of keycaps correctly, and you win absolutely nothing but my excitedly raised eyebrows. At any rate, it would be nice to know approximately how many keycaps adorn the conference room wall of a certain hotel in Denver, CO. Be sure to check out [mathinpenn]’s reddit post for the close-up shot.

Do you rock a sweet set of peripherals on a screamin’ desk pad? Send me a picture along with your handle and all the gory details, and you could be featured here!

Historical Clackers: the Zerograph

This is a machine that was quite far ahead of its time. The Zerograph could instantly transmit and print text, arguably making it the first Telex machine. The patent language declares it a printing telegraph.
Image via Antikey Chop
But unlike most telegraphs, which transmitted dots and dashes, the Zerograph sent actual words, at the rate of 25 per minute. Not bad for 1895.

Its inventor, Leonard “Leo” Ulrich Kamm, was quite renowned for his work in the field of cinema, having created a film-less movie projector, the Kammatograph. Instead of film, it used a circular glass plate with images arranged in a spiral.

The Zerograph worked using a pendulum system. Actuate the pendulum of one machine, and a second, synced machine would match the distance of each swing. The second Zerograph would then map that distance to one of the 36 characters and type it.

Each swing was different for each character, but none took more than half a second. The pendulum returned to a zero position after each swing, hence the name Zerograph. So, why haven’t you heard of this machine before? History shows that Kamm invested zero effort in marketing and improving the thing, due to focusing his efforts on the Kammatograph instead.

ICYMI: Vacuum-forming Keycaps Sucks, But the Result is Slick

Image by [Drygol] via RetrohaxWhile there are all kinds of keycap options out there, there’s nothing quite like a custom set. What’s interesting is the method that [Drygol] chose — vacuum-forming several at once using a 3D-printed scaffold.

The really neat part here is that the keycap is left intact underneath. So not only do the legends show through (provided you use the right type of vinyl), no keycaps are harmed during this process.

In fact, you could almost say they are being preserved under there. Good news for, say, an Amiga keyboard like the one pictured.

The process looks simple, but seems tedious: each one is carefully trimmed from the vinyl, and the edges are made triangular and folded neatly underneath. The end result is quite unique and stunning, though, so it seems worth it to me. If only I had a vacuum-forming table.

Got a hot tip that has like, anything to do with keyboards? Help me out by sending in a link or two. Don’t want all the Hackaday scribes to see it? Feel free to email me directly.

Could carbon fiber inflict the same kind of damage on the human body as asbestos? That’s the question which [Nathan] found himself struggling with after taking a look at carbon fiber-reinforced filament under a microscope, revealing a sight that brings to mind fibrous asbestos samples. Considering the absolutely horrifying impact that asbestos exposure can have, this is a totally pertinent question to ask. Fortunately, scientific studies have already been performed on this topic.
Example SEM and TEM images of the released particles following the rupture of CFRP cables in the tensile strength test. (Credit: Jing Wang et al, Journal of Nanobiotechnology, 2017)
While [Nathan] demonstrated that the small lengths of carbon fiber (CF) contained in some FDM filaments love to get stuck in your skin and remain there even after washing one’s hands repeatedly, the aspect that makes asbestos such a hazard is that the mineral fibers are easily respirable due to their size. It is this property which allows asbestos fibers to nestle deep inside the lungs, where they pierce cell membranes and cause sustained inflammation, DNA damage and all too often lung cancer or worse.

Clearly, the 0.5 to 1 mm sized CF strands in FDM filaments aren’t easily inhaled, but as described by [Jing Wang] and colleagues in a 2017 Journal of Nanobiotechnology paper, CF can easily shatter into smaller, sharper fragments through mechanical operations (cutting, sanding, etc.) which can be respirable. It is thus damaged carbon fiber, whether from CF reinforced thermal polymers or other CF-containing materials, that poses a potential health risk. This is not unlike asbestos — which when stable in-situ poses no risk, but can create respirable clouds of fibers when disturbed. When handling CF-containing materials, especially for processing, wearing an effective respirator (at least N95/P2) that is rated for filtering out asbestos fibers would thus seem to be a wise precaution.

The treacherous aspect of asbestos and kin is that diseases like lung cancer and mesothelioma are not immediately noticeable after exposure, but can take decades to develop. In the case of mesothelioma, this can be between 15 and 30 years after exposure, so protecting yourself today with a good respirator is the only way you can be relatively certain that you will not be cursing your overconfident young self by that time.

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LEDs are a wonderful technology. You put in a little bit of power, and you get out a wonderful amount of light. They’re efficient, cheap, and plentiful. We use them for so much!

What you might not have known is that these humble components have a secret feature, one largely undocumented in the datasheets. You can use an LED as a light source, sure, but did you know you can use one as a sensor?

Dual-Use Devices

The concept of using an LED as a sensor is much like using a speaker as a microphone. Flip things around, and instead of emitting light, the LED senses it instead. You can see the effect quite simply by using a multimeter. Hook up the leads of a multimeter to your LED, and set it to measure current. Point the LED towards the sun, and you’ll likely pick up a reading. While the LED is sensitive to light, it’s usually on quite a small range of wavelength, unlike traditional photodiodes.
Forrest Mims liked to use op-amps to boost the output from LEDs used as sensors. Credit:Forrest Mims via Make article
But how to use this effect? Well, you can go multiple routes. If you’re of the analog tilt, you can hook the LED up to the inputs of an op-amp, using the device to amplify the output if you so desire. Just about any garden-variety op-amp can be used in such a way that it produces a higher output voltage the more light falls on the LED.
Two tristate pins let you use an LED for emitting light and sensing it. Credit: MERL research paper
However, you can go so much further, as the bright minds at Mitsubishi Electric Research Laboratories (MERL) determined back in 2003. Following their example, you might like to hook the LED up to a microcontroller. Setting it up in a “reverse biased” mode allows it to act as a sensor when attached to an IO pin, instead of acting as a light emitter. To do this, simply attach the LED’s anode to ground, while connecting the cathode to an I/O pin in a high state. This achieves the “reverse bias,” and charges the inherent capacitance of the LED. The capacitance is small, so this only takes a fraction of a second. Then, the IO pin can be switched to an input, and the capacitance of the LED will discharge into the microcontroller pin. The more light, the more current induced in the LED, and the faster the LED’s capacitance will discharge. Measure how long it takes for the voltage to drop below the IO pin’s digital logic level, and you can sense light levels with a simple IO pin.

Researchers were able to communicate between microcontrollers over a distance of a few centimeters using nothing but regular LEDs. Data rates reached 250 bits/sec. Credit: MERL, research paper
In fact, the team at MERL realized that you could go even further. The humble LED could become a “last centimeter” communications device, used as both light transmitter and receiver. To achieve this, one simply had to insert the LED between two tristate IO pins on a microcontroller. With the anode driven high and the cathode driven low, the LED would light. Flipped the other way, and the LED would be reverse biased. Then, one of the tristate pins could be set to input mode to read the LED as a sensor.

As suggested by the team at MERS, LEDs can be used as sensors in all kinds of innovative applications. You could use a TV’s power LED to detect light levels, and thus adjust screen brightness appropriately. You can even do simple proximity sensing, using an array of LEDs to act as emitters and sensors in turn. You could even use status LEDs on small devices to do bidirectional communication if you were so inclined.

And yet! We almost never use LEDs for any of these things. Realistically, while LEDs are sensors, they’re not excellent sensors. We have far better phototransistors, photodiodes, and other sensors available these days. This technique could be useful to you, if you’re trying to design a device with the bare minimum part count or as cheaply as possible. Or, if you want to put surprise functionality into a device that has just an LED on board. But in the real world, this technique doesn’t get a whole lot of use. Futzing around with nifty LED tricks takes more engineering time than just speccing a proper sensor, after all.

Still, the technique has found some real applications. LEDs used in this way do have the benefit of being quite selective as to wavelength, and can be quite stable over time. The legendary Forrest Mims took advantage of this, putting LED sensors to use in a variety of scientific apparatus. Indeed, his ozone measurement device relied on this technique, and was so reliable it proved there was a drift error in NASA’s own Nimbus-7 satellite.
Some researchers believe PerLEDs could enable the creation of touchscreen displays that don’t need additional sensor elements beyond the LEDs themselves. Credit: Bao, et al, research paper
There’s also hope in the rapidly-advancing field of perovskite technology. Perovskite LEDs, or PerLEDs, could use advanced semiconductor materials to create devices that act as both good light sources and capable photodetectors. The hope is that they might be good enough to create touchable displays that need no additional sensor for touch. Instead, the PerLED array would act as both display and sensor. However, for now, the research is at an early stage, and the instability of perovskites means any practical applications are a long way off.

It’s also worth noting that this technique doesn’t work on a lot of modern LEDs. Namely, addressable LEDs, self-flashing LEDs, and anything of that ilk. That’s because this technique relies on hooking up a microcontroller directly to the LED die itself. Many modern “smart” LEDs don’t break out the pins themselves, only providing pins for the controller chip inside. Thus, don’t expect to use this technique with your NeoPixels, WS2812Bs, or anything like that.

Ultimately, using LEDs as a sensor is a fun technique. It’s also highly useful if you’re doing specific things with certain wavelengths of light. Barring that, though, it’s a great party trick to keep in your toolbox, because you never know when it’ll come in handy.