Stealing Joules From An Aluminium-Air Battery

While batteries are cheap and readily obtainable today, sometimes it’s still fun to mess around with their less-common manifestations. Experimenting with a few configurations, Hackaday.io user [will.stevens] has assembled an aluminium-air battery and combined it with a joule thief to light an LED.

To build the air battery, soak an activated charcoal puck — from a water filter, for example — in salt-saturated water while you cut the base off an aluminium can. A circle of tissue paper — also saturated with the salt water — is pressed between the bare charcoal disk and the can, taking care not to rip the paper, and topped off with a penny and a bit of wire. Once clamped together, the reaction is able to power an LED via a simple joule thief.

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Measuring Air Flow with Ultrasonic Sensors

Measuring air flow in an HVAC duct can be a tricky business. Paddle wheel and turbine flow meters introduce not only resistance but maintenance issue due to accumulated dust and debris. Being able to measure ducted airflow cheaply and non-intrusively, like with this ultrasonic flow meter, could be a big deal for DIY projects and the trades in general.

The principle behind the sensor [ItMightBeWorse] is working on is nothing new. He discovered a paper from 2015 that describes the method that measures the change in time-of-flight of an ultrasonic pulse across a moving stream of air in a duct. It’s another one of those “Why didn’t I think of that?” things that makes perfect sense in theory, but takes some engineering to turn into a functional sensor. [ItMightBeWorse] is using readily available HC-SR04 sensor boards and has already done a proof-of-concept build. He’s getting real numbers back and getting close to a sensor that will go into an HVAC automation project. The video below shows his progress to date and hints at a follow-up video with more results soon.

Here’s wishing [ItMightBeWorse] the best of luck with his build. But if things go sideways, he might look to our post-mortem of a failed magnetic flow meter for inspiration.

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Air-Powered Wheelchair Goes Like The Wind

Electric wheelchairs are responsible for giving back independence to a great many people the world over. They do have their limitations, however, including long recharge times and a general aversion to large amounts of water. Being weatherproof is one thing, but taking one to a waterpark is another thing entirely. Fear not, for The University of Pittsburgh has the answer: the air-powered wheelchair.

Known as the PneuMobility project, the chair relies on a couple of compressed air tanks as a power source. They appear to be a of composite construction, which would cut down on weight significantly and help reduce risk of injury in the case of a failure. The air is passed through a system of valves to a special compressed air motor, allowing the user to control the direction of travel. Unfortunately details on the drive system are scant — we’d love to know more about the design of the drivetrain! Reportedly a lot of the components come from the local hardware store, though we haven’t seen a whole lot of compressed air drive motors on the racks of Home Depot/Bunnings/et al.

Range for the wheelchairs is listed as about 1/3 of an electric wheelchair but recharging compressed air takes minutes, not hours. Developed by the university’s Human Engineering Research Laboratories, the wheelchair isn’t just a one off. There are plans to supply ten of the machines to the Morgan’s Wonderland amusement park to enable wheelchair users to share in the fun of the water park.

We’ve seen some great wheelchair hacks in the past, too – like this chair built specifically for the sand dunes! Video after the break.

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Scissor Lift Shoes May Be OSHA Compliant

It’s been said that necessity is the mother of all invention. This was probably the fundamental principle behind the show “Inspector Gadget”, a story about a police agent who has literally any technology at his grasp whenever he needs it. Although the Inspector’s gadgets get him into trouble more often than not (his niece Penny usually solves the actual crimes), the Inspector-inspired shoes that [Make it Extreme] built are a little bit more useful than whatever the Inspector happens to have up his sleeve (or pant leg, as the case may be).

If a fabrication tour de force, [Make it Extreme] built their own “Go Go Gadget Legs”, a set of pneumatically controlled stilts that allow the wearer to increase their height significantly at the push of a button. We often see drywall contractors wearing stilts of a similar height, but haven’t seen any that are able to raise and lower the wearer at will. The team built the legs from scratch, machining almost every component (including the air pistons) from stock metal. After some controls were added and some testing was done, the team found that raising one foot at a time was the safer route, although both can be raised for a more impressive-looking demonstration that is likely to throw the wearer off balance.

The quality of this build and the polish of the final product are incredibly high. If you have your own machine shop at home this sort of project might be within your reach (pun intended). If all you have on hand is a welder, though, you might be able to put together one of [Make it Extreme]’s other famous builds: a beer gun.

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Tiny Pipe Organ Needs Tiny Church

There are a lot of unusual listings on eBay. If you’re wondering why someone would have a need for shredded cash, or a switchblade comb, or some “unicorn meat” (whatever that is), we’re honestly wondering the same thing. Sometimes, though, a listing that most people would consider bizarre finds its way to the workbench of someone with a little imagination. That was the case when [tinkartank] found three pipe organ pipes on eBay, bought them, and then built his own drivers.

The pipes have pitches of C, D, and F# (which make, as far we can tell, a C add9 flat5 no3 chord). [tinkartank] started by firing up the CNC machine and creating an enclosure to mount the pipes to. He added a church-like embellishment to the front window, and then started working on the controls for the pipes. Each pipe has its own fan, each salvaged from a hot air gun. The three are controlled with an Arduino. [tinkartank] notes that the fan noise is audible over the pipes, but there does seem to be an adequate amount of air going to each pipe.

This project is a good start towards a fully functional organ, provided [tinkartank] gets lucky enough to find the rest of the pipes from the organ. He’s already dreaming about building a full-sized organ of sorts, but in the meantime it might be interesting to use his existing pipes to build something from Myst.

Heat Duct Rover Explores Stink, Rescues Flashlight

It all started with a bad smell coming from the heat register. [CuddleBurrito] recalled a time when something stinky ended up in the ductwork of his folks’ house which ended up costing them big bucks to explore. The hacker mindset shies away from those expenditures and toward literally rolling your own solution to investigating the funk. In the process [CuddleBurrito] takes us on a journey into the bowels of his house.

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“Superfan” Gaming Peripheral Lets You Feel Your Speed

Virtual reality has come a long way but some senses are still neglected. Until Smell-O-Vision happens, the next step might be feeling the wind in your hair. Perhaps dad racing a sportbike or kids giggling on a rollercoaster. Not as hard to build as you might think, you probably have the parts already.

HAD - Superfan4Off-the-shelf devices serve up the seeing and hearing part of your imaginary environment, but they stop there. [Jared] wanted to take the immersion farther by being able to feel the speed, which meant building his own high power wind generator and tying it into the VR system. The failed crowdfunding effort of the “Petal” meant that something new would have to be constructed. Obviously, to move air without actually going on a rollercoaster requires a motor controller and some fans. Powerful fans.

A proponent of going big or going home, [Jared] picked up a pair of fans and modified them so heavily that they will launch themselves off of the table if not anchored down. Who overdrives fans so hard they need custom heatsinks for the motors? He does. He admits he went overboard and sensibly way overbudget for most people but he built it for himself and does not care.

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