Imagine that you’re starting a project where you need to measure temperature and humidity. That sounds easy in the abstract, but choosing a real device out of many involves digging into seemingly infinite details and trade-offs that come with them. If it’s a low-stakes monitoring project, picking the first sensor that comes to mind might suffice. But when the project aims to control an AC system in an office of temperature-sensitive coders, it pays to take a hard look at the source of all information: the sensor.
Continuing a previous article I would like to use that same BMaC project from that article as a way to illustrate how even a couple of greenhorns can figure out how to pick everything from environmental sensors to various actuators, integrating it into a coherent system that in the end actually does what it should.
Continue reading “Picking the Right Sensors for Home Automation”
Seltzer water – that bubbly, carbonated water that disappoints sugar-craving children everywhere – has experienced a steady rise in popularity over the past few years. This is perhaps partly fueled by the availability of countertop carbonators such as the SodaStream.
Not satisfied with the tedious and pedestrian process of manually carbonating individual bottles of water, [piyoman] has instead built a tidy little tap of unlimited cold, filtered seltzer. It’s no easy gag. The build uses a commercial carbonator pump, reverse osmosis water filter, bulk tank, and a standard CO2 cylinder to create a constant source of carbonated water. Most of this setup is stuffed into a dorm-sized fridge (tetris-style) and topped with a fancy beer faucet to dispense the resulting bubblewater.
At roughly $800 for the documented system, you need to have a great reason to build your own. But [piyoman] provides detailed instructions, a parts list, and suggestions for cost savings and future improvements if you do take on a system like this for your seltzer needs.
Cheaper Carbonation Options
While looking at how DIY carbonation has been done in the past we found [Richard Kinch’s] Carbonating at Home with Improvised Equipment and Soda Fountains page which dives into many other options. His site – a wonderful, dense demonstration of the beauty of “web 1.0” – walks through the basics of carbonated water, discusses CO2 tanks and gauges, and shows how to build a simple carbonation cap for making seltzer in standard PET soda bottles.
For those of us who grow up around natural swimming holes, algae are the reason we have to wash after taking a dip. Swimmer’s itch* or just being covered in green goop is not an attractive way to spend an afternoon. Lumping all algae together is not fair, some of it is nasty but some of it is delicious and humans have been eating it for generations.
If you are thinking that cases of algae cuisine are not widespread and that algae does not sound appealing, you are not alone. It is a tough sell, like convincing someone to try dandelions for the first time. It may not warrant a refrigerator section in the grocery store yet, but algae can produce protein-rich food which doesn’t require a lot of processing.
Currently, there is a lot of work to be done to bring up the efficiency of algae farms, and Qualitas has already started. The leaps they are making signify just how much room we have for improvement. The circulating paddle wheels, which can be seen in the video below the break, use one-third of the energy from their previous version. Their harvester uses one-thirtieth! Right now, their biggest cost comes from tanks of carbon dioxide, which seems off given that places such as power plants pay to get rid of the stuff. That should give some food for thought.
The 2018 Hackaday prize could use some algal submissions and you could take that to the bank. Ready to start growing your own algae, automate the process. It may also keep you from tripping while walking to the grocery store, or you can print with it.
Continue reading “Algae On Your Plate”
To those of us in the corporate world, the conference room is where hope goes to die. Crammed into a space too small for the number of invitees, the room soon glows with radiated body heat and the aromas of humans as the time from their last shower gradually increases. To say it’s not a recipe for productivity is an understatement at best.
Having suffered through too many of these soporific situations, [Charles Ouweland] took matters into his own hands and built this portable air quality meter for meetings. With an OLED display on top and sensors inside, it displays not only the temperature, humidity, and barometric pressure, but also the CO₂ concentration and the levels of volatile organic compounds (VOC), noxious substances sometimes off-gassed from building materials, furniture upholstery, and coworkers alike.
The monitor quantifies his meeting misery, which we’re sure wins him points with his colleagues. For our part, though, what we find interesting is his design process. He started where many of us would, with an Arduino Uno. The sensor modules, a CCS811 for VOC and CO₂ as well as a BME280 for temperature, humidity, and pressure, both needed 3.3 volts, so he added a regulator to knock the Arduino’s 5-volt supply into range and some MOSFETs for level matching. Things were getting bulky, though, so he set about reducing the component count. The Uno went by stripping out its already programmed MCU. That killed the need for the regulator and MOSFETs, since everything would be happy with 3.3 volts. A few more rounds of optimization led to the final product, compact enough to run on a pair of AA batteries.
This is a great lesson in going from prototype to product. And it’s so compact, it could even ride on top of a Roomba to map the conference room’s floor-level air quality.
When it comes to making music, there are really only a few ways to create the tones needed — pluck something, blow into something, or hit something. But where does that leave this dry-ice powered organ that recreates tunes with wind chimes and blocks of solid CO2?
It turns out this is firmly in the “hit something” camp, as [Leah Edwards] explains of her project. When the metal wind chime tubes come in contact with dry ice, the temperature difference sublimates the solid CO2. The puff of gas lifts the tube slightly, letting it fall back against the brick of dry ice and making a tone. The process is repeated rapidly, providing a vibrato effect while the tube is down. [Leah] used solenoids to lift the tubes and, having recently completed a stint at National Instruments, a bunch of NI gear to control them. The videos below show a few popular tunes and a little bit about the organ build. But what — no songs from Frozen?
We can easily imagine this same build using an Arduino or some other microcontroller. In fact, it puts us in mind of a recent reed organ MIDI project that has a few ideas to offer, like ways to quiet those solenoids. Continue reading “Wind Chimes and Dry Ice Make an Unusual Musical Instrument”
Q: What do you call 8000 dead mosquitoes in a Mason jar?
A: A good start. And [Dan Rojas]’s low-tech mosquito trap accomplished the feat in two nights with nothing fancier than a fan and a bottle of seltzer.
We know what you’re thinking: Where’s the hack? Why not at least use a laser sentry gun to zap skeeters on the fly? We agree that [Dan]’s mosquito trap, consisting of a powerful fan to create suction and a piece of window screen to catch the hapless bloodsuckers, is decidedly low-tech. But you can’t argue with results. Unless he’s fudging the numbers, a half-full Mason jar of parasite cadavers is pretty impressive. And you have to love the simplicity of the attractant he’s using. Mosquitoes are attracted to the CO2 exhaled by tasty mammals, but rather than do something elaborate with a paintball gun cartridge or the like, [Dan] simply cracks a bottle of seltzer and lets it outgas. Dead simple, and wickedly effective. The trapped bugs quickly desiccate in the strong air stream, aided by a few spritzes of isopropyl alcohol before cleaning the screen, which leaves them safely edible to frogs and insects.
Simple, cheap, and effective. Sounds like a great hack to us. And it’s really just a brute-force implementation of this mosquito-killing billboard for areas prone to Zika.
Continue reading “Eradicating Mosquitoes from Your Backyard — with Seltzer?”
We’ve probably all made matchstick rockets as kids. And around here anything that even vaguely looks like a rocket will get some imaginary flight time. But [austiwawa] is making some really cool 3D printed rockets that use common CO2 cartridges as a propellant. You can see them in action in the video below.
You might think just sticking a CO2 cylinder in a 3D printed jacket isn’t such a big deal, but [austiwawa] really went the extra mile. He read up on how to make the rocket stable (by manipulating the center of gravity versus the center of pressure) and explains what he had to do to get the rockets flying like you’d expect.
In addition, the launch tube is pretty interesting. A 3D printed part holds a sharp point and a spring. You lock the spring and when released it punches a clean hole in the propellant casing. The actual tube is a long piece of PVC pipe. From the video, it looks like these little rockets fly pretty high.
Judging from the video, the rocket body and launcher came from TinkerCAD. The way [austiwawa] put the fins on was both simple and clever.
Of course, you could also use Coke and propane, if you like. We’ve also seen some pretty cool setups with compressed air. Check out the rockets in action after the break,
Continue reading “3D Printed Rockets are a Gas”