A Bold Experiment In A Decentralised Low Voltage Local DC Power Grid

January, for many of us in the Northern Hemisphere, can be a depressing month. It’s cold or wet depending where you live, the days are still a bit short, and the summer still seems an awfully long way away. You console yourself by booking a ticket to a hacker camp, but the seven months or so you’ll have to wait seems interminable.

If you want an interesting project to look forward to, take a look at [Benadski]’s idea for a decentralised low voltage local DC power grid for the upcoming SHA 2017 hacker camp in the Netherlands. The idea is to create a network that is both safe and open for hacking, allowing those with an interest in personal power generation to both have an available low-voltage power source and share their surplus power with other attendees.

The voltage is quoted as being 42V DC +/- 15%, which keeps it safely under the 50V limit set by the European Low Voltage Directive. Individuals can request a single 4A connection to the system, and villages can have a pair of 16A connections, which should supply enough for most needs. Users will need to provide their own inverters to connect their 5V or 12V appliances, fortunately a market served by numerous modules from your favourite Far Eastern sales portal.

This project will never be the solution to all power distribution needs, but to be fair that is probably not the intention. It does however provide a platform for experimentation, collaboration, and data gathering for those interested in the field, and since it is intended to make an appearance at future hacker camps there should be the opportunity for all that built up expertise to make it better over time.

We’ve touched on this subject before here at Hackaday, with our look at the availability of standard low voltage DC domestic connectors.

Wind turbine image: Glogger (CC BY-SA 3.0) via Wikimedia Commons.

The Internet Of Dirt, A Texting Plant

We will all at some point have forgotten to water a plant. If we’re lucky then the limp vegetation we return to will magically revive when we rush to water it, if not then we have the shame of an empty plant pot to remind us of our folly.

No matter, you might be thinking, we can bring technology to bear on the problem, and automate it with a microcontroller! [Bonnie] has done just that, with a capacitive soil sensor feeding an ESP8266-based Adafruit Feather HUZZAH, which in turn logs soil humidity data with the Adafruit IO online service. An IFTTT applet monitors the data, and triggers a notification when moisture falls to the point at which watering is required.

The Instructables write-up gives a comprehensive step-by-step guide to the whole process, including the code, so it’s a project that almost anyone could try as well as a basic introduction to using an online service with a piece of hardware. We can’t help asking, though, whether it might have been better to have had the system do the watering rather than merely administer a prod to its fleshy horticulturist creator. Perhaps that’s left to anyone else building one to add as an enhancement.

Quite a few plant watering automation projects have found their way onto these pages over the years, from this one using car parts to a system with an impressively simple valve made by compressing a flexible pipe. The ultimate watering device though has to be this fully autonomous greenhouse robot.

OpenAg Is A Personal Food Computer

When a device that calls itself a personal food computer lands in your timeline, what image springs to mind? A cloud-connected diet aid perhaps, advertised on TV infomercials by improbably fit-looking Californian ladies crediting all their health to a palm-sized unit that can be yours for only 199 dollars. Fortunately that proved not to be the case, and on further reading our timeline story was revealed to be about a computerized farming device.

The OpenAg Food Computer  from the MIT Media Lab Open Agriculture Initiative bills itself as:

“a controlled-environment agriculture technology platform that uses robotic systems to control and monitor climate, energy, and plant growth inside of a specialized growing chamber”

It takes the form of a tabletop enclosure in which so-called climate recipes to replicate different conditions for plant growth can be tested. It’s probably fair to say that in this most basic form it is more of an educational device than one for full-scale food production, though they are applying the same technologies at a much greater scale. Their so-called “Food servers” are banks of OpenAg environments in freight containers, which definitely could be used to provide viable quantities of produce.

The good news is that the project is open source, and their latest story is that they have released version 2.0(alpha) of the device. If you are interested, you can read the documentation, and find all the resources you need to build one on their GitHub repository. They page linked above has a video that’s very much of the slick PR variety rather than the nuts-and-bolts, so we’ve sought out their build video for you below the break instead. Continue reading “OpenAg Is A Personal Food Computer”

Automated Vacuum Lettuce Seed Placement

[Jethro Tull] is a name you may well associate with a 1970s prog/folk rock band featuring a flautist, but the original [Tull] was an inventor whose work you benefit from every day. He was a British lawyer and landowner who lived over the turn of the 18th century, and who invented among other things the mechanical seed drill.

Were [Tull] alive today he would no doubt be impressed by the work of [Akash Heimlich], who has created an exquisite vacuum seed placer for his rooftop hydroponic lettuce farm. Unlike the continuous rows of seed on the Berkshire earth of [Tull]’s farm, the lettuce seed must be placed in an even grid on a foam substrate for the hydroponic equivalent. This was an extremely tedious task when done by hand, so [Akash] set about automating the process with a vacuum seeder that is a thing of beauty.

It uses a simple yet effective mechanism involving a row of pipettes connected to a vacuum line, that are rotated over a vibrating hopper of seeds from which each one collects a single seed, before being rotated back over the foam where the seeds are dropped in a neat row through 3D-printed funnels. The foam is advanced, and the process is repeated until there is a neat grid of seeds. In only four minutes it can deliver 150 seeds, reducing several hours work into under half an hour.

The whole machine is controlled by an Arduino, with a couple of stepper motors to move foam and pipettes alongside the vibrator motor. You can see its operation in the video below the break.

Continue reading “Automated Vacuum Lettuce Seed Placement”

Thermoelectric Paint Opens Prospect Of Easier Energy Harvesting

We will all be used to the thermoelectric effect in our electronic devices. The property of a junction of dissimilar conductors to either generate electricity from a difference in temperature (the Seebeck effect), or heating or cooling the junction (the Peltier effect). Every time we use a thermocouple or one of those mini beer fridges, we’re taking advantage of it.

Practical commercial thermoelectric arrays take the form of a grid of semiconductor junctions wired in series, with a cold side and a hot side. For a Peltier array the cold side drops in temperature and the hot side rises in response to applied electric current, while for a Seebeck array a current is generated in response to temperature difference between the two sides. They have several disadvantages though; they are not cheap, they are of a limited size, they can only be attached to flat surfaces, and they are only as good as their thermal bond can be made.

Researchers in Korea have produced an interesting development in this field that may offer significant improvements over the modules, they have published a paper describing a thermoelectric compound which can be painted on to a surface. The paint contains particles of bismuth telluride (Bi2Te3), and an energy density of up to 4mW per square centimetre is claimed.

Continue reading “Thermoelectric Paint Opens Prospect Of Easier Energy Harvesting”

Breathe Easy with a Laser Cutter Air Filter

A laser cutter is a great tool to have in the shop, but like other CNC machines it can make a lousy neighbor. Vaporizing your stock means you end up breathing stuff you might rather not. If you’re going to be around these fumes all day, you’ll want good fume extraction, and you might just consider a DIY fume and particulate filter to polish the exhausted air.

15203365_644939182347358_619032134291602214_nWhile there’s no build log per se, [ZbLab]’s Facebook page has a gallery of photos that show the design and build in enough detail to get the gist. The main element of the filter is 25 kg of activated charcoal to trap the volatile organic compounds in the laser exhaust. The charcoal is packed into an IKEA garbage can around a prefilter made from a canister-style automotive air cleaner – [ZbLab] uses a Filtron filter that crosses to the more commonly available Fram CA3281. Another air cleaner element (Fram CA3333) makes sure no loose charcoal dust is expelled from the filter. The frame is built of birch ply and the plumbing is simple PVC. With a 125mm inlet it looks like this filter can really breathe, and it would easily scale up or down in size according to your needs.

No laser cutter in your shop to justify this filter, you say? Why not build one? Or, if you do any soldering, this downdraft fume extractor is a good way to clear the air.

Daisy Kite Wind Turbine: Now You Can Buy One

The Isle of Lewis is the largest of the Scottish Outer Hebrides, sitting in the North Atlantic off the west coast of the Scottish mainland. It is the first landfall after thousands of miles of ocean for a continuous stream of Atlantic weather systems, so as you might imagine it is a place in which there is no shortage of wind.

It is thus the perfect situation for a wind power startup, and in the aptly-named Windswept and Interesting Ltd it has one that is pushing the boundaries. Their speciality is the generation of power from spinning kites, arrays of kites that transmit power to a ground-based generator through the rotation of their lines, and because they release their designs as open source they are of extra interest to us.

Of course, if you are a seasoned reader you’ll now be complaining that we’ve covered this story before when they had an entry in the 2014 Hackaday Prize, so what’s new? The answer is that the 2014 story was a much earlier iteration than their current multi-level kite array, and that they have now reached the point of bringing their products to market. You can buy one of their prototypes right now, and there is a soon-to-be-launched crowdfunding campaign for their latest model. It’s not exactly cheap, but this first product is the result of 5 years of product development, and it is pretty obvious that more is on the way. For any open hardware startup to stay afloat that long is an impressive achievement, to do so in a field in which you are not surrounded by a huge supporting industry in the way for example electronics startups are is nothing short of amazing.

If you would like to have a go at building one of their spinning kites, you can do so with full instructions released under a Creative Commons licence, but for non kite builders their website is a fascinating read in its own right. Their YouTube channel  in particular has a wealth of videos of previous tests as well as design iterations, and is one on which many readers will linger for a while. Below the break we’ve put one of their most recent, a montage showing the kite evolution over the years.

Continue reading “Daisy Kite Wind Turbine: Now You Can Buy One”