Ultra-powerful Pneumatic Hand Dryer

Have you been let down by the inadequate performance of a hand dryer? We know that feel. [tesla500] recently installed a centralized compressed air system and decided he might as well do something interesting it, so he built an ultra-powerful hand dryer that rivals the performance of any hand dryer on the market.

[tesla500] set out to make a clone of the Dyson Airblade. He started out with a simple prototype out of milled aluminum with one nozzle. Even with just one nozzle the hand dryer performed incredibly well. Next he designed a Solidworks model with a smaller nozzle gap (50um) and 4 total nozzles which has even better performance and emulates the airflow of the Airblade.

The dryer was originally controlled with a foot-activated pneumatic valve, but it severely restricted airflow. [tesla500] decided to use a 3/8″ solenoid valve instead, which solved the airflow restriction. According to [tesla500], the dryer works even better than the Airblade when running at full pressure, although he notes that you might need to watch out if you have any open wounds on your hands.

Using a Headphone Jack as a UART

We’ve seen audio ports being used to establish a communications channel between a computer and a microcontroller before, but nothing quite as slick as this. [Gordon] is using a webpage running on a tablet to send Javascript to a microcontroller where the entire program is interpreted.

[Gordon] is using the Espruino Pico, a board that’s on Kickstarter right now. This tiny board is built around a javascript interpreter, allowing code to be written and updated on the fly without mucking around with bootloaders.

This technique can be expanded to provide bidriectional communication between a microcontroller and a computer. On the project Github, [Gordon] used the microphone pin on a TRRS jack to sent data to a computer. It needs two more resistors, but other than that, it’s as simple as the one-way communications setup.

[Gordon] put together a few demos of the program, including one that will change the color of some RGB LEDs in response to input on a webpage.

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SDR: Satellite Death Receiver

Halloween may be over, but [happysat] has found a way to listen to the dead. Satellites, that is, specifically those in the 136-138 MHz and 150-400 MHz ranges. He’s using an RTL-SDR dongle and a QFH antenna to detect the death throes of decommissioned navigation and space research satellites.

[happysat] was listening to NOAA/Meteor on the 137MHz band when he made this discovery. When a satellite is near end of life, the last bit of fuel is used to push it into graveyard orbit. This doesn’t always work, however, and when the light is just right, a chemical reaction makes the long-dead batteries conduct and these satellites in purgatory transmit once more.

They’re not sending out anything proprietary useful, just unmodulated carrier that sometimes interferes with currently operational satellites on the 136-138 MHz band. [happysat] captured some audio from two of the oldest satellites that are still broadcasting, and links to a TLE set of dead satellites he created. Check out his frequency database for SDR# as well. Don’t have a weather satellite-capable antenna? Build one!

[via /r/RTLSDR]

A Tiny Arcade Machine With Tinier Buttons

Building a MAME machine around a Raspberry Pi has been the standard build for years now, and tiny versions of full-sized arcade machines have gone from curiosity to commonplace. [diygizmo] just built one of these tiny arcades, but the fit and finish of this one puts it above all others. There’s a real, miniature joystick in there, along with 3D printed adapters for tact switches to make this one look like a lilliputian version of a full size standup MAME cabinet.

The entire enclosure is 3D printed, and most of the electronics are exactly what you would expect: A Raspberry Pi, 2.5″ LCD, and a battery-powered speaker takes up most of the BOM. Where this build gets interesting is the buttons and joystick: after what we’re sure was a crazy amount of googling, [diygizmo] found something that looks like a normal arcade joystick, only smaller. Unable to find a suitable replacement for arcade buttons, [diygizmo] just printed their own, tucked a tact switch behind the plastic, and wired everything up.

Add in some decals, paint, and the same techniques used to create plastic model miniatures, and you have a perfect representation of a miniature arcade machine.

Retrotechtacular: The Jet Story

A plane from Britain is met in the US by armed security. The cargo? An experimental engine created by Air Commodore [Frank Whittle], RAF engineer air officer. This engine will be further developed by General Electric under contract to the US government. This is not a Hollywood thriller; it is the story of the jet engine.

The idea of jet power started to get off the ground at the turn of the century. Cornell scholar [Sanford Moss]’ gas turbine thesis led him to work for GE and ultimately for the Army. Soon, aircraft were capable of dropping 2,000 lb. bombs from 15,000 feet to cries of ‘you sank my battleship!’, thus passing [Billy Mitchell]’s famous test.

The World War II-era US Air Force was extremely interested in turbo engines. Beginning in 1941, about 1,000 men were working on a project that only 1/10 were wise to. During this time, American contributions tweaked [Whittle]’s design, improving among other things the impellers and rotor balancing. This was the dawn of radical change in air power.

Six months after the crate arrived and the contracts were signed, GE let ‘er rip in the secret testing chamber. Elsewhere at the Bell Aircraft Corporation, top men had been working concurrently on the Airacomet, which was the first American jet-powered plane ever to take to the skies.

In the name of national defense, GE gave their plans to other manufacturers like Allison to encourage widespread growth. Lockheed’s F-80 Shooting Star, the first operational jet fighter, flew in June 1944 under the power of an Allison J-33 with a remarkable 4,000 pounds of thrust.

GE started a school for future jet engineers and technicians with the primary lesson being the principles of propulsion. The jet engine developed rapidly from this point on.

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Developed on Hackaday: Crowd- funding Campaign Start!

For a little less than a year open source enthusiasts from all over the globe got together to work on an open source offline password keeper. We narrated our progress here on Hackaday and always asked our readers’ opinion when critical decisions were to be made.

Today, the wait is finally over: the Mooltipass crowdfunding campaign finally arrived.

In some of our Developed on Hackaday series posts we noticed that it was tricky for us to convey the benefits of the device we were developing. The first 3 minutes of our video therefore explain good security practices and how the Mooltipass can help users with their credentials security. For our readers that may not have followed our adventure since its beginning, the campaign’s text will provide them with a simple (yet detailed) explanation of what the Mooltipass can do. Finally, our geeky readers will find at the end of our write-up a few links supporting our claims. We would have liked offering cheaper pledges but we unfortunately need to hire professional javascript developers to finish our app & extension.

Our Mooltipass Developed on Hackaday series therefore come to an end. We would like to thank you for your support and hope that you enjoyed seeing an idea materialize into a crowdfunding-ready product!

Controlling a Block Camera with an RC Transmitter

The world of drones and FPV remote-controlled aircraft is rapidly expanding, airframes are getting bigger, and the demand for even cooler AV gear is higher than ever. [elad] got his hands on a Sony block camera that is able to zoom in on a scene – great if you want to get close to the action while still flying a safe distance away. Controlling the zoom on these cameras is usually done through RS232, but [elad] made it work with an RC transmitter.

The camera [elad] is using is a Sony FCB-EX11D block camera with a standard SD resolution sensor. This camera has 10x optical zoom, making it a great solution to aerial surveillance, the only problem being the RS232 connection and the VISCA protocol. [elad] used an Arduino to listen in on the elevator channel from an RC receiver, translating that to something the camera will understand. The result is a controllable zoom on a camera that could easily take to the skies.

The entire camera package, with Arduino and electronics included, weighs in at about 100 grams. That’s about the same as a GoPro, and would fit perfectly on a camera gimbal. The only problem is getting a transmitter with enough channels or someone else to operate the camera while flying. Video below.

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