Low Power Challenge: Keep Plants Green And Clean With E-Paper Smart Tags

February 25, 2023 by 7 Comments

There are plenty of reasons to devote oneself to the care of houseplants — after all, a room full of bright, glossy-leaved plants can be a joy to behold, and that’s not even one of the more tangible benefits they bring. But as any green thumb knows, there’s a fine line between a healthy, vibrant plant and one that’s soon to give up the ghost.

If your thumb tends less toward green and more toward the brown and crusty side of things, something like [Jon]’s Smart Plant system might be just the thing for you. These low-power plant tags are built around increasingly ubiquitous e-Paper displays, like the kind you might find in a retail shelf price tag system. The current version of [Jon]’s tags uses a Waveshare 2.9″ tricolor display and a PCB with capacitive probes that stick into the plant’s soil. An ESP32-S lives on the top section of the PCB, along with a 1,000 mAh LiPo pack that’s charged off USB-C. The design includes an optional solar panel for keeping the battery topped off, which may or may not help depending on the plant’s place in your personal jungle.

In addition to the soil moisture sensor, the Smart Tag has an ambient temperature and humidity sensor and a light sensor — everything to keep your plant happy. The power-hungry sensors are only powered on when the Smart Tag pops out of deep sleep; this gives and estimated five to six weeks runtime between charges, without solar charging of course. The e-Paper display shows custom graphics of the plant’s current environmental state, and the same data is also available via Home Assistant thanks to the ESPHome firmware.

These are nice-looking plant tags that can really pull a lot of weight in keeping plants healthy. Check out the other offerings in our Low Power Challenge Contest, and maybe get an entry together yourself.

2023 Hackaday.io Low-Power Challenge

UV Photography Box Is Great For Shooting Fancy Rocks

February 19, 2023 by 9 Comments

If you want to shoot photographs of various fluorescent UV-related phenomena, it’s hard to do so when ambient light is crowding out your subject. For this work, you’ll want a dedicated UV photography box, and [NotLikeALeafOnTheWind] has a design that might just work for you.

The build is set up for both UVA and UVC photography. Due to the danger posed by the latter, and even the former in some cases, the builder recommends never using the box with a direct-view camera. If it must be done, the eyepiece should be covered to avoid any exposure to harmful light. The key rule? Never look directly into a UV source.

Light sources that can be used include UV LEDs, lamps, and tubes. The box is sealed to keep out external light. It then features a turntable that can be manipulated from outside the box, allowing samples inside to be rotated as necessary. Using a camera with a macro or wide-angled lens is recommended for the work.

The photographs taken inside the box are stunning. They remind us of childhood museum trips, where we marvelled at the magic of the fluorescent rock displays. We’ve featured some other great fluorescence projects before, too. If you’re cooking up your own great scientific builds in the lab, we’d love to see those too. Hit us up on the tipsline!

A Single-Resistor Radio Transmitter, Thanks To The Power Of Noise

January 27, 2023 by 36 Comments

One of the great things about the Hackaday community is how quickly you find out what you don’t know. That’s not a bad thing, of course; after all, everyone is here to get smarter, right? So let’s work together to get our heads around this paper (PDF) by [Zerina Kapetanovic], [Miguel Morales], and [Joshua R. Smith] from the University of Washington, which purports to construct a low-throughput RF transmitter from little more than a resistor.

This witchcraft is made possible thanks to Johnson noise, also known as Johnson-Nyquist noise, which is the white noise generated by charge carriers in a conductor. In effect, the movement of electrons in a material thanks to thermal energy produces noise across the spectrum. Reducing interference from Johnson noise is why telescopes often have their sensors cooled to cryogenic temperatures. Rather than trying to eliminate Johnson noise, these experiments use it to build an RF transmitter, and with easily available and relatively cheap equipment. Continue reading “A Single-Resistor Radio Transmitter, Thanks To The Power Of Noise” →

Big Chemistry: Liquefied Natural Gas

December 21, 2022 by 44 Comments

The topic of energy has been top-of-mind for us since the first of our ancestors came down out of the trees looking for something to eat that wouldn’t eat them. But in a world where the neverending struggle for energy has been abstracted away to the flick of a finger on a light switch or thermostat, thanks to geopolitical forces many of us are now facing the wrath of winter with a completely different outlook on what it takes to stay warm.

The problem isn’t necessarily that we don’t have enough energy, it’s more that what we have is neither evenly distributed nor easily obtained. Moving energy from where it’s produced to where it’s needed is rarely a simple matter, and often poses significant and interesting engineering challenges. This is especially true for sources of energy that don’t pack a lot of punch into a small space, like natural gas. Getting it across a continent is challenging enough; getting it across an ocean is another thing altogether, and that’s where liquefied natural gas, or LNG, comes into the picture.

Continue reading “Big Chemistry: Liquefied Natural Gas” →

A Binaural Microphone For The Great Outdoors

December 17, 2022 by 15 Comments

A binaural recording is designed to mimic as closely as possible the experience of listening through human ears, and thus binaural microphones are often shaped like the human head with the microphone cartridges placed where the ears would be. That’s not the only way to make a binaural microphone though, and the Crown Stereo Ambient Sampling System, or SASS, did the same thing with a pair of pressure zone microphones for outdoor recordings. [Filip Mulier] doesn’t have one of the originals, but he’s done his best to make a SASS-like microphone of his own.

The attractive thing about this design is its simplicity, making use of foam sheets for the main body, with packing board as a rain deflector and a couple of layers of non-woven cloth as a wind filter. Perhaps best of all though are the recordings, in which we hear ambient recording at its finest. Listen with headphones, we suggest the dawn chorus.

If binaural recording and stereo interests you, we’ve taken a closer look in the past.

Nanoaetherphone Is A Special MIDI Controller

December 14, 2022 by 11 Comments

MIDI controllers can be simple straightforward keyboards, or wild magical devices that seem to snatch notes from the very aether itself. As you might expect from the name, the Nanoaetherphone II is one of the latter.

The device is inspired by the Theremin, and was built to celebrate its 100th anniversary. The Nanoaetherphone II is all about using sensors to capture data from wireless hand-wavey interactions, and turn it into MIDI messages. To this end, it has an LDR sensor for detecting light levels, which determines volume levels. This is actuated by the user’s thumb, blocking the sensor or allowing ambient light to reach it. At the front of the handheld unit, there is also an ultrasonic range sensor. Depending on how close the sensor is to the user’s hand or other object determines the exact note sent by the device. As a MIDI controller, it is intended to be hooked up to an external synthesizer to actually generate sound.

The overall concept isn’t too complicated, and the design makes it easy to pickup and play. We imagine it could even be foolproofed by programming it only to play notes from a given scale or mode, allowing for easy soloing without too many of those ill-tempered blue notes. Jazz enthusiasts might prefer it to just spit out any and all notes, of course.

We love a good MIDI controller around these parts, and we’ve seen everything from knitted models to those made out of old phones. Video after the break.

Continue reading “Nanoaetherphone Is A Special MIDI Controller” →

Hyundai To Lead US Market For Hydrogen Fuel Cell Trucks

December 13, 2022 by 96 Comments

Hydrogen has long been touted as a potential fuel of the future. While it’s failed to catch on in cars as batteries have taken a strong lead, it still holds great promise for larger vehicles like trucks.

Hyundai have been working diligently in this space over the last few years, with its Xcient line of fuel-cell powered trucks. It’s set to dominate the world of hydrogen trucking in the US as it brings a fleet of vehicles to California next year.

Continue reading “Hyundai To Lead US Market For Hydrogen Fuel Cell Trucks” →