Graphene is an interesting material, but making enough of the stuff to do something useful can be a little tough. That’s why we’re always on the lookout for new methods, like this electrochemical process for producing graphene in bulk.
You probably know that graphene is a molecular monolayer of carbon atoms linked in hexagonal arrays. Getting to that monolayer is a difficult proposition, but useful bits of graphene can be created by various mechanical and chemical treatments of common graphite. [The Thought Emporium]’s approach to harvesting graphene from graphite is a two-step process starting with electrochemical exfoliation. Strips of thin graphite foil are electrolyzed in a bath of ferrous sulfate, resulting in the graphite delaminating and flaking off into the electrolyte. After filtering and cleaning, the almost graphene is further exfoliated in an ultrasonic cleaner. The result is gram quantity yields with very little work and at low cost.
There’s plenty of effort going into new methods of creating graphene these days, whether by barely controlled explosions or superheating soybean oil. But will graphene be the Next Big Thing? The jury is still out on that.
Continue reading “Graphene from Graphite by Electrochemical Exfoliation”
Ultrasonic repellent devices used to keep away insects, rodents, birds, and even large animals have been around for quite a while, but their effectiveness depends on who you ask. Some critters just don’t seem affected, while some others definitely will avoid being around such a device. Deploying a few of these devices to scare off animals seems to be working quite well for [Ondřej Petrlík]. Around where he lives, the fields of tall grass need to be mowed down during the spring. Unfortunately, the tall grass is ideal for young, newborn animals to stay hidden and safe. The mowing machines would often cripple and hurt such animals, and [Ondřej] desperately wanted to solve the problem and prevent these mishaps.
He built an electronic repeller to keep away wild animals and their young from his farm/ranch/range back in the Czech Republic. He used an Arduino Mini to drive a large piezo transducer to scare away the wild animals from the vicinity of the device. He likely used a high enough frequency beyond human range, but we’ll know more when he publishes his code and details. There are also a few large 10mm LED’s – either to visually locate the device or help drive the animals away in conjunction with the ultrasound, with an LDR that activates the LEDs at night. Using the Arduino helps to turn on the transducer at random intervals, and hopefully, he is using a range of different frequencies so the animals don’t become immune to the device.
His first prototype was cobbled together using vanilla, off the shelf parts. An Arduino, a step up converter, an LDR, a couple of LEDs, a reed switch for powering it on via a magnet, and a large ultrasonic transducer, all powered by three alkaline AA batteries. He stuffed it all inside a weatherproof molded enclosure, holding it all together with a lot of hot glue. This didn’t make it very rugged for the long-term, outdoor field use. While the prototype worked well, he needed several of the devices to be placed all around his farm. To make assembly easy and make it more reliable, he designed a custom PCB to fit in the weather proof enclosure. This allowed him to easily mount all the required parts for a more reliable result. His project is still a work in progress, so if you have worked with these types of ultrasonic repellent devices to keep away animals, and have any insights that may help him, do chime in with your comments. [Ondřej] seems pretty satisfied with the results so far.
It has become a common sight, a must-have feature on modern cars, a row of ultrasonic sensors embedded in the rear bumper. They are part of a parking sensor, an aid to drivers for whom depth perception is something of a lottery.
[Haris Andrianakis] replaced the sensor system on hs car, and was intrigued enough by the one he removed to reverse engineer it and probe its workings. He found a surprisingly straightforward set of components, an Atmel processor with a selection of CMOS logic chips and an op-amp. The piezoelectric sensors double as both speaker and microphone, with a CMOS analogue switch alternating between passing a burst of ultrasound and then receiving a response. There is a watchdog circuit that is sent a tone by the processor, and triggers a reset in the event that the processor crashes and the tone stops. Unfortunately he doesn’t delve into the receiver front-end circuitry, but we can see from the pictures that it involves an LC filter with a set of variable inductors.
If you have ever been intrigued by these systems, this write-up makes for an interesting read. If you’d like more ultrasonic radar goodness, have a look at this sweeping display project, or this ultrasonic virtual touch screen.
An ultrasonic beacon is an inaudible sound with encoded data that can be used by a listening device to receive information on just about anything. Beacons can be used, for example, inside a shop to highlight a particular promotion or on a museum for guided tours where the ultrasonic beacons can encode the location. Or they can be used to track
people consumers. Imagine if Google find outs… oh, wait… they already did, some years ago. As with almost any technology, it can be used to ‘do no harm’ or to serve other purposes.
Researchers from the Technische Universitat Braunschweig in Germany presented a paper about Ultrasonic Side Channels on Mobile Devices and how can they be abused in a variety of scenarios , ranging from simple consumer tracking to deanonymization. These types of ultrasonic beacons work in the 18 kHz – 20 kHz range, which the human being doesn’t have the ability to hear, unless you are under twenty years old, due to presbycusis. Yes, presbycusis. This frequency range can played via almost any speaker and can be picked up easily by most mobile device microphones, so no special hardware is needed. Speakers and mics are almost ubiquitous nowadays, so there is a real appeal to the technology.
Continue reading “Ultrasonic Tracking Beacons Rising”
This one is both wild enough to be confused as a conspiracy theory and common sense enough to be the big solution staring us in the face which nobody realized. Until now. Oak Ridge National Laboratory and General Electric (GE), working on a grant from the US Department of Energy (DOE), have been playing around with new clothes dryer technology since 2014 and have come with something new and exciting. Clothes dryers that use ultrasonic traducers to remove moisture from garments instead of using heat.
If you’ve ever seen a cool mist humidifier you’ll know how this works. A piezo element generates ultrasonic waves that atomize water and humidify the air. This is exactly the same except the water is stored in clothing, rather than a reservoir. Once it’s atomized it can be removed with traditional air movement.
This is a totally obvious application of the simple and inexpensive technology — when the garment is laying flat on a bed of transducers. This can be implemented in a press drying system where a garment is laid flat on a bed or transducers and another bed hinges down from above. Poof, your shirt is dry in a few seconds.
But individual households don’t have these kinds of dryers. They have what are called drum dryers that spin the clothes. Reading closely, this piece of the puzzle is still to come:
They play [sic] to scale-up the technoloogy to press drying and eventually a clothes dryer drum in the next five months.
We look at this as having a similar technological hurdle as wireless electricity. There must be an inverse-square law on the effect of the ultrasonic waves to atomize water as the water moves further away from the transducers. It that’s the case, tranducers on the circumference of a drum would be inefficient at drying the clothing toward the center. This slide deck hints that that problem is being addressed. It talks about only running the transducers when the fabric is physically coupled with the elements. It’s an interesting application and we hope that it could work in conjunction with traditional drying methods to boost energy savings, even if this doesn’t pan out as a total replacement.
With a vast population, cost adds up fast. There are roughly 125 M households in the United States and the overwhelming majority of them use clothes dryers (while many other parts of the world have a higher percentage who hang-dry their clothing). The DOE estimates $9 billion a year is spent on drying clothes in the US. Reducing that number by even 1/10th of 1% will pay off more than tenfold the $880,000 research budget that went into this. Of course, you have to outfit those households with new equipment which will take at least 8-12 years through natural attrition, even if ultrasonics hit the market as soon as possible.
Continue reading “A Cool Mist that Dries Your Clothes”
While the rise of electronic cigarettes and vaping has led to many aggravated bystanders, an installation in Germany may have found a vapor of a different ilk. Rather than nicotine, this cloud of vapors is full of tequila which precipitates out into glasses (or people) who happen to be nearby.
The cloud generator uses ultrasonic devices to vibrate the tequila molecules until they form a fine mist. The mist is delivered outward towards the sculpture, where a delicious cloud forms. From there, the cloud literally rains tequila out into its original, drinkable tequila form. It appears to take a while to gather enough tequila from the cloud, though, so there is a convenient tap on the side that will dispense it without all the rigmarole.
Basically this is a nebulizer which is using tequila and dispersing the output rather than directing it. You’re unlikely to get a large enough gasp for inebriation, but technically there is
an opportunity a risk here of becoming second-hand drunk.
The installing is an effort by the Mexican Tourism Board to encourage Germans to take a break from the rain in favor of visiting sunny Mexico, we’d have to say that the effort seems to be a success. Once there, hopefully any visitors will be able to enjoy a perfect margarita or two as well.
Anyone with grandparents already knows that in ye olden days, televisions did not have remote control. Your parents probably still complain about how, as children, they were forced to physically walk over to the TV in order to switch between the three available channels. In these modern times of technological wonder, we have voice control, programmable touch screen remotes, and streaming services that will automatically play an entire season of the show you’re binge watching. However, before these, and before the ubiquitous infrared remote, television manufacturers were experimenting with ways to keep kids from having to run across the living room every time the channel needed to be changed.
Early remote controls were simply wired affairs — nothing too surprising there. But, it wasn’t long before methods of wireless control were being introduced. One early effort called the Flashmatic would shine light onto a photoelectric cell on the television set to control it. Of course, it might also be controlled by unintended light sources, and users had to have good aim to hit the sensor. These issues soon led to the introduction of the Zenith Space Command remote control, which used ultrasonic frequencies to control the TV.
Continue reading “Command Alexa With a Completely Mechanical Vintage Remote Control”