Fishing For AirPods With Magnets

July 30, 2017 by Dan Maloney 35 Comments

Note to self: if you’re going to hack at 4 in the morning, have a plan to deal with the inevitable foul ups. Like being able to whip up an impromptu electromagnetic crane to retrieve an AirPod dropped out a window.

Apartment dweller [Tyler Efird]’s tale of woe began with a wee-hours 3D print in need of sanding. Leaning out his third-story window to blow off some dust, he knocked one AirPod free and gravity did the rest. With little light to search by and a flight to catch, the wayward AirPod sat at the bottom of a 10-foot shaft below his window, keeping company with a squad of spiders for two weeks. Unwilling to fork over $69 and wait a month and a half for a replacement, [Tyler] set about building a recovery device. A little magnet wire wound onto a bolt, a trashed 100-foot long Ethernet cable, and a DC bench supply were all he needed to eventually fish up the AirPod. And no spiders were harmed in the making of this hack.

Need to lift something a little heavier than an AirPod? A beefy microwave oven transformer electromagnet might be the thing for you. And confused about how magnets even work in the first place? Check out our primer on magnetism.

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Stealing Joules From An Aluminium-Air Battery

July 28, 2017 by James Hobson 36 Comments

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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Play With A Papercraft Electronics Activity Book

July 27, 2017 by John Baichtal 7 Comments

As conductive ink becomes readily available and in greater varieties, we’re starting to see some intriguing applications. [Marion Pinaffo] and [Raphaël Pluviange] created a book of papercraft projects that employ silver-based ink for making a circuit’s wires, carbon-based ink for resistance, as well as color-changing ink. Electronics components’ leads are slipped into slits cut into the paper, connected to conductive-ink traces.

[Marion] and [Raphaël] use 555s, ATtiny85s, watch batteries, and other hardware to make each activity or project unique. A number of projects use a rolling ball bearing to make beeps in a piezo speaker. They also created beautifully designed pages to go with the electronics.

It looks like a fun way for neophytes to play around with electronics, and once the paper part is kaput, the user would be left with the hardware. Imagine one of those beginners googling to find the pinout of the Tiny85 or discovering the Stepped Tone Generator and makes one with the 555.

If you like this project you’ll appreciate the working papercraft organ and papercraft resistor calculator we previously published.

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Maywa Denki’s Nonsense Machines

July 26, 2017 by Elliot Williams 9 Comments

We just spent a few hours trying to figure out Japanese techno-performance-art-toy company [Maywa Denki]. As self-described “parallel-world electricians”, the small art collective turns out strange electro-mechanical instruments, creates bellows-powered “singing” sculptures, and puts on concerts/demos/lectures. And if you desperately need an extension cord in the shape of a fish skeleton, [Maywa Denki] has you covered. Writing about art is like dancing about economics, so first we’ll just drop a few of our favorites and let you decide.

On the serious art front are “nonsense machines” like SeaMoonsII and Wahha Go Go. The most iconic performance piece is probably the Pachi-Moku, a set of finger-snap-activated wooden gongs mounted on anime-style wings. And then there are “toys” like Mr. Knocky and the Otamatone, here demonstrated playing some DEVO.

There’s a lot going on here. The blue suits of the assembly-line worker, the back story as a small-electronics “company”, and the whole art-as-commodity routine is a put into contrast with the mad-inventor schtick make sense both as a reaction against conformist, corporatist postwar Japanese culture or as a postmodern hat-tip to the realities of the modern art scene. But mostly, what comes across is the feeling that [Novmichi Tosa], the “president” of [Maywa Denki] just loves to make crazy gizmos.

How else do you explain the gas-powered, chomping mouth-full-of-knives, Poodle’s Head?

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Measuring Air Flow With Ultrasonic Sensors

July 26, 2017 by Dan Maloney 23 Comments

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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Rapidly Prototyping RF Filters

July 25, 2017 by Brian Benchoff 25 Comments

RF filters are really just a handful of strategically placed inductors and capacitors. Yes, you can make a 1 GHz filter out of through-hole components, but the leads on the parts turn into inductors at those frequencies, completely ruining the expected results in a design.

The solution to this is microstrip antennas, or carefully arranged tracks and pads on a PCB. Anyone can build one of these with Eagle or KiCad, but that means waiting for an order from a board house to verify your design. [VK2SEB] has a better idea for prototyping PCB filters: use copper tape on blank FR4 sheets.

The first, and simplest, filter demonstrated is a simple bandstop filter. This is really just a piece of fiberglass with copper laminated to one side. Two RF connectors are soldered to the edges and a strip of copper tape strung between them. Somewhere around the middle of this copper tape, [VK2SEB] put another strip of copper tape in a ‘T’ configuration. This is the simplest bandstop filter you can make, and the beauty of this construction is that it can be tuned with a razor blade.

Of course, a filter can only be built with copper tape if you can design them, and for that [SEB] is turning to software. The Qucs project is a software tool for designing and simulating these microstrip filters, and after inputting the correct parameters, [SEB] got a nice diagram of what the filter should look like. A bit of taping, razor blading, and soldering and [SEB] had a working filter connected to a spectrum analyzer. Did it work? To a limited extent; the PCB material probably wasn’t right, and board houses are more accurate than a razor blade, but [SEB] did manage to create a 10 GHz filter out of fiberglass and copper tape.

You can check out the video for this experiment below.

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Soap bubble machine: animation to reality

How To Turn An Animation Into A Soap Bubble Machine

July 22, 2017 by Steven Dufresne 15 Comments

Post an animation on Reddit of a workable machine that looks neat and does something cool and the next day someone will have built it. That’s what happened when [The-Big-Ship] uploaded an animation of a clever bubble making machine — though we had to look twice to convince ourselves that it wasn’t real. The next day [Over_Engineered_2] posted a video of his working one.

We often hear that you need precision CAD software such as Solidworks and AutoCAD to design a functional machine but the animation was done using Cinema 4D, used for films such as Iron Man 3 and Tron: Legacy. This shows that you can at least get a reassurance that the basic mechanics will fit and move together without having to design precision parts.

That’s not to say that reality didn’t interfere with implementing it though. In [Over_Engineered_2]’s video below he points out that the bigger ring of the original animation didn’t work with his small motor and propeller, and had to switch to the smaller ring. Also, note that the ring needed guide rails on the sides to keep it from twisting, something a real world ignoring animation can get away without. Check out the videos below to see the two in action.

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