Copper Oxide Thermoelectric Generator Can Light An LED

March 26, 2014 by Mathieu Stephan 54 Comments

On Hackaday, we usually end up featuring projects using building blocks (components, platforms…) that can be bought on the market. We however don’t show many hacks that rely on basic physics principles like the one shown in the picture above.

In the video embedded below, [nylesteiner] explains that copper oxide can be formed when heating a copper wire using a propane flame. When two oxidized wires are placed in contact with each other, an electrical current is produced when one wire is heated much hotter than the other. The trade-off is that the created thermocouple generates a small voltage but a ‘high’ current. However, when you cascade 16 junctions in series you can generate enough voltage to light up an LED. Even though the complete system isn’t particularly efficient at converting heat into electricity, the overall result is still quite impressive in our opinion. We advise our readers to give a look at [nylesteiner]’s article and blog to discover his interesting adventures.

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Authentic Blue Blueprints

March 21, 2014 by Brian Benchoff 31 Comments

blue

At one point in history, blueprints were actually blue. Now, if you even see a dead tree version of plans or assemblages, they’re probably printed off with a plotter or large format printer. You can, however, make your own blueprints at home, as [Tyler] shows us in his Hackaday Project.

Back in the olden days, master drawings were traced onto large sheets of transparent film. These master prints were then laid over paper prepared with Potassium Ferricyanide and Ferric Ammonium Citrate to create an insoluble Prussian Blue background for the prints. Developing is easy – just expose the transparent positive and undeveloped paper to UV light, in the form of fluorescent bulbs or the sun.

[Tyler] began his blueprint creation process by getting a few design sketches of the RSI Aurora and Nautilus, editing them on a computer, and printing them out on transparency sheets. A solution of equal parts Potassium Ferricyanide and Ferric Ammonium Citrate were painted onto a piece of paper and allowed to dry. Exposing was a simple matter of laying the transparency over the undeveloped paper and setting it out in the sun for 20 minutes or so. After that, it’s a simple matter of washing off the unexposed chemicals and letting the newly created blueprint dry.

It’s a simple technique, but also very, very cool. Not exactly practical, given a plotter can spit out an architectural or assembly drawing of any building, vehicle, or device in a few minutes, but just the ticket for art pieces or extremely odd engineers.

Thanks [Sarah] for sending this in.

Billboard Advertises Engineering School, Manufactures Potable Water

March 13, 2014 by Kristina Panos 24 Comments

It’s a remarkable thing when ad agencies manage to help people in the course of advertising. The University of Technology and Engineering Peru (UTEC) was looking for ways to increase enrollment. They went to the Peruvian offices of agency DraftFCB and came away with the idea to install a billboard that converts Lima’s water-saturated coastal desert air into potable water.

Perhaps the only downside is that it requires electricity, and not just for those cool neon water drops. There are five generators that capture the humidity and use reverse osmosis to purify the water. Each of these units has a tank that holds 20L. From there, the clean water is aggregated in a main tank and can be collected from a faucet at the base of the billboard. In just three months, the billboard produced over 9,000L (2500 gallons) of potable water for people who would otherwise draw polluted water from wells.

We love to see hacks that help. Use your powers for good, like re-purposing humid air and pollution. Make the jump to see a short video and an artist’s conception of the billboard’s innards.

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Fetching Etchings For Stainless Steel

March 9, 2014 by Kristina Panos 25 Comments

What do you do when you have a 10-gallon brew kettle (or any other stainless steel or aluminium thing) with no volume markings (or Hack a Day logos)? If you’re [Itsgus], you use science to etch some markings with a few household items and a 9V and you call it a day.

[Itsgus] used 1/4c vinegar and 1/4tsp of salt to form an electro-etchant and applied it with a Q-tip connected to the negative terminal of a 9V. He used tape to connect a wire between the positive terminal and the kettle. The vinegar dissolves the salt, creating negatively charged ions. Connected correctly to a 9V, the process removes metal where the current flows. If you were to connect it in reverse, you would add a small amount of metal.

The process only takes a few seconds. When the etchant starts to sizzle and bubble, Bob’s your uncle. Even though the stainless steel’s natural coat re-oxidizes over the etches, you should probably wash that thing before you brew. If you prefer adding metal to removing it, try electroplating copper on the cheap.

Here’s The Dirt On Printing With Pollution

March 5, 2014 by Kristina Panos 34 Comments

[Anirudh] and his friends were sitting around reminiscing about India. In particular, they recalled riding around in auto-rickshaws in stifling heat, watching their skin turn black from the exhaust. They started thinking about all of the soot and pollution in crowded cities the world over and wondered whether the stuff could be re-purposed for something like printer ink. That’s how they came up with their soot/pollution printer.

They created a soot-catching pump which they demonstrate with a burning candle. The pump mixes the soot particles with rubbing alcohol and an oil substrate and sends the ink to an HP C6602 inkjet cartridge. They used [Nicolas C Lewis]’s print head driver shield for Arduino to interface with the cartridge, turning it into a 96dpi printing head that uses only five pins.

[Anirudh] and his friends plan to design a carbon separator using charged plates to capture the soot particles from pollution sources and filter out dust. Be sure to check out their demonstration video after the jump.

Update: In response to [Hirudinea]’s comment about mining the carbon from cars, [Anirudh] is now looking for collaborators (tinkerers, filmmakers, DIY enthusiasts) to move forward with the idea of re-purposing carbon. Email him at anirudhs@mit.edu.

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Making OLEDs In The Kitchen Sink

March 2, 2014 by Brian Benchoff 27 Comments

When [Ian] first set out to create a homebrew OLED, he found chemical suppliers that wouldn’t take his money, manufacturers that wouldn’t talk to him, and researchers that would actively discourage him. Luckily for us, he powered through all these obstructions and created his own organic LED.

Since at least one conductor in an OLED must be transparent, [Ian] settled on ITO – indium tin oxide – for the anode. This clear coating is deposited on glass, allowing it to conduct electricity and you can buy it through a few interesting suppliers. For the cathode, [Ian] is using a gallium-indium-tin eutectic, an alloy with a very low melting point that allowed him to deposit a small puddle in his OLED stack.

With the anode and cathode taken care of, the only thing left was the actual LED. For this, [Ian] had some success with MEH-PPV, a polymer that is capable of electroluminescence. On top of this is a film of PEDOT:PPS, another polymer that serves to block electrons.

The resulting yellow-green blob of an OLED actually works, and is at least as good as some of the other homebrew semiconductor illumination projects we’ve seen around here. This is only a start, though, and [Ian] plans on putting a whole lot more time into his explorations of organic LEDs.

Improving A Homebrew CT Scanner With Barium

February 26, 2014 by Brian Benchoff 22 Comments

CTscanner

[Peter] has been working on his homebrew CT scanner for a while, and it’s finally become something more than a spinning torus of plywood. He’s managed to image the inside of a few pieces of produce using an off-the-shelf radiation detector and a radioactive barium source

When we last saw [Peter]’s CT scanner, he had finished the mechanical and electronic part of the Stargate-like device, but the radioactive source was still out of reach. He had initially planned on using either cadmium 109 or barium 133. Both of these presented a few problems for the CT scanner.

The sensor [Peter] is a silicon photodiode high energy particle detector from Radiation Watch this detector was calibrated for cesium with a detection threshold of around 80keV. This just wasn’t sensitive enough to detect 22keV emissions from Cd109, but a small add-on board to the sensor can recalibrate the threshold of the sensor down to the noise floor.

Still, cadmium 109 just wasn’t giving [Peter] the results he wanted, resulting in a switch to barium 133. This was a much hotter source (but still negligible in the grand scheme of radioactivity) that allowed for a much better signal to noise ratio and shorter scans.

With a good source, [Peter] started to acquire some data on the internals of some fruit around his house. It’s still a slow process with very low resolution – the avocado in the pic above has 5mm resolution with an acquisition time of over an hour – but the whole thing works, imaging the internal structure of a bell pepper surprisingly well.