Thermoelectric Generator Shines Where The Sun Doesn’t

March 31, 2018 by 81 Comments

For off-grid renewable electricity, solar seems to make sense. Just throw some PV panels on the roof and you’re all set to stick it to the man, right? But the dirty little secret of the king of clean energy is that very few places on the planet get the sort of sunshine needed to make residential PV panels worth their installation cost in the short term, and the long-term value proposition isn’t very good either.

The drearier places on the planet might benefit from this high-power thermoelectric generator (TEG) developed and tested by [TegwynTwmffat] for use on a wood burning stove. The TEG modules [Tegwyn] used are commercially available and rated at 14.4 volts and 20 watts each. He wisely started his experiments with a single module; the video below shows the development of that prototype. The bulk of the work with TEGs is keeping the cold side of the module at a low enough temperature for decent performance, since the modules work better the higher the difference in temperature is across the module. A finned heatsink and a fan wouldn’t cut it for this application, so a water-cooled block was built to pump away the heat. A successful test led to scaling the generator up to 10 modules with a very impressive heatsink, which produced about 120 watts. Pretty good, but we wonder if some easy gains in performance would have come from using heat sink compound on the module surfaces.

Using thermal differences to generate electricity is nothing new, but a twist on the technique is getting attention lately as a potential clean energy source. And who knows? Maybe [TegwynTwmffat]’s or one of the other Hackaday Prize 2018 entries will break new ground and change the world. What’s your big idea?

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Hackaday’s Irish Excursion Is On 7 April

March 21, 2018 by 7 Comments

Try something a bit out of the ordinary with us on 7 April. Spend a Saturday with Hackaday in Dublin without really knowing what to expect. This is the Unconference format, and we’ve fallen in love with the spontaneity and consistently fascinating talks that come out of it.

We’ve booked a fantastic hall in the Temple Bar district of Dublin, lined up snacks throughout the day and dinner for all who attend, plus there’s an after bar and we’ll buy the first round. All of this is yours if you grab one of the rapidly disappearing free tickets.

What we ask of you is to come prepared to give a 7 minute talk on something you’re really excited about right now. This is low-pressure; the point of an Unconference is to learn about what people are working on right now (not to see a 40 minute talk that was polished over several months). There will not be enough time for absolutely everyone to speak but we’ll get through as many as we can and make sure there’s an interesting mash-up of topics throughout the day.

To break the ice, we have a few “ringers” who we’ve asked to lead off each talk session. Beth ‘pidge’ Flanagan is an embedded and Linux expert who is well-known for her work on OpenEmbedded and Yocto and will talk about “how the sausage is made” specifically surrounding some advance metering infrastructure. Rachel “Konichiwakitty” will be speaking. Rachel was at our London Unconference back in September and we’re excited to hear about the stem cell research she’s been doing as part of her Ph.D. work. James Twomey will be on hand to go into some of the craft of stage magic, and also talk about what we can learn from the battery-free magic of crystal set radios like the “foxhole” radios built during WWII.

DesignSpark LogoThere are already enough people to pack the place and we only have about 20 tickets left, so hurry up and grab yours.

This event is made possible, free of charge to the attendees, with generous support from DesignSpark, the innovation arm of RS Components. DesignSpark is the exclusive sponsor of the Hackaday Dublin Unconference.

You Don’t Need To Be Tony Stark To Afford This Hand Controller

March 9, 2018 by 4 Comments

Proving that duct tape really can do anything, [StudentBuilds] uses it to make a workable controller out of a glove. To be fair, there are a few more bits too, including paper coated with pencil graphite and tin foil, which forms a variable resistor you can read with an Arduino analog input. You can see the entire thing in the video below.

The source code is simple at this point — eventually, he plans to control a robotic hand with the controller, but that’s later. However, there’s no promised link to the code in the description, so you’ll have to freeze frame and type. However, it is pretty simple — just read the analog pin values to determine the specific values for each finger.

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You’ve Never Seen A Flipping Eyeball Like This One!

February 24, 2018 by 20 Comments

Inspired by some impressive work on textile flip-bit displays, and with creative steampunk outfits to create for Christmas, [Richard Sewell] had the idea for a flippable magnetic eye in the manner of a flip-dot display. These devices are bistable mechanical displays in which a magnet is suspended above a coil of wire, and “flipped” in orientation under the influence of a magnetic field from the coil.

In [Richard]’s case the eyeball was provided by a magnetic bead with a suitable paint job, and the coil was a hand-wound affair with some extremely neat lacing to keep it all in place. The coil requires about 200 mA to ensure the eye flips, and the job of driving it is performed by a Digispark ATTiny85 board with an LM293 dual H-bridge driver upon which the two bridges are wired in parallel. The whole is mounted in the centre of a charity shop brooch that has been heat-treated to give a suitable aesthetic.

You can see the eyeball in all its glory in the two videos below the break, and should you be curious you can also read our write-up of the original pieces from [Irene Posch] that inspired it.

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At 71,572 KM, You Won’t Beat This LoRa Record

February 22, 2018 by 29 Comments

A distance record for LoRa transmission has been set that you probably won’t be able to beat. Pack up your gear and go home, nothing more to achieve here. At a superficial reading having a figure of 71,572 km (44,473 miles) seems an impossible figure for one of the little LoRa radio modules many of us have hooked up to our microcontrollers, but the story isn’t quite what you’d expect and contains within it some extremely interesting use of technology.

So the folks at Outernet have sent data over LoRa for that incredible distance, but they did so not through the little ISM band modules we’re used to but over a suitably powerful Ku-band uplink to a geostationary satellite. They are also not using the LoRaWAN protocols of the earthbound systems, but simply the LoRa modulation scheme. So it’s not directly comparable to terrestrial records such as the 702 km we reported on last year, and they are the first to admit that.

Where their achievement becomes especially interesting though is in their choice of receiver. We are all used to Ku-band receivers, you may even have one on your house somewhere for satellite TV. It will probably involve a parabolic dish with a narrow beam width and an LNB whose horn antenna is placed at its focus. It would have required some skill and effort to set up, because it has to be pointed very carefully at the satellite’s position in the sky. Outernet’s mission of delivering an information service with the lowest possible barrier to entry precludes the extra expense of shipping a dish and providing trained staff to align it, so they take a very different approach. Their receiver uses either an LNB horn or a small patch antenna pointing at the satellite, with none of the dishes or phased arrays you might be used to in a Ku-band installation.

You might wonder how such a receiver could possibly work with such a meagre antenna, but the secret lies in LoRa’s relatively tiny bandwidth as well as the resistance to co-channel interference that is a built-in feature of the LoRa modulation scheme. Even though the receiver will be illuminated by multiple satellites at once it is able to retrieve the signal and achieve a 30 kb/s data rate that they hope with technical refinements to increase to 100 kb/s. This rate will be enough over which to push an SD video stream to name just one of the several examples of the type of content they hope to deliver.

It’s likely that the average Hackaday reader will not be hiring satellite uplink time upon which to place their LoRa traffic. But this story does provide a demonstration of LoRa’s impressive capabilities, and will make us look upon our humble LNBs with new eyes.

Via ABOpen.

Retrotechtacular: AM Radios, Core Memory, And Color TV, What Was Hot In Chips In ’73

February 16, 2018 by 23 Comments

As part of writing tech stories such as those we feature here at Hackaday, there is a huge amount of research to be done.  We trawl through pages and pages of obscure blogs, videos, and data sheets. Sometimes we turn up resources interesting enough that we file them away, convinced that they contain the nucleus of another story at some point in the future.

Today’s topic of entertainment is just such a resource, courtesy of the Internet Archive. It’s not a video as we’d often provide you in a Retrotechtacular piece, instead it’s the February 1973 edition of the Fairchild Semiconductor Linear Integrated Circuits Catalog. Books like this one that could be had from company sales representatives were highly prized in the days before universal Internet access to data sheets, and the ink-on-paper datasheets within it provide a fascinating snapshot of the integrated electronics industry as it was 45 years ago.

The first obvious difference between then and now is one of scale, this is a single volume containing Fairchild’s entire range. At 548 pages it wouldn’t have been a slim volume by any means, but given that Fairchild were at the time one of the big players in the field it is unimaginable that the entire range of a 2018 equivalent manufacturer could be contained in the same way. Given that the integrated circuit was at the time an invention barely 15 years old, we are looking at an industry still in relative infancy.

The catalog has a series of sections with familiar headings: Operational amplifiers, comparators, voltage regulators, computer/interface, consumer, and transistor/diode arrays with analog switches. Any modern catalog will have similar headings, and there are even a few devices you will find have survived the decades. The μA741 op-amp (page 64) from its original manufacturer has not yet become a commodity product here, and it sits alongside familiar devices such as the μA7800 series (page 201) or μA723 (page 194) regulators.

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