Fail Of The Week: The Accidental FM Radio

[B Arnold] is hearing voices and needs help from the Hackaday community. But before any of you armchair psychiatrists run off to WebMD, rest assured that [B Arnold] suffers not from schizophrenia but rather has an RF coupling problem.

The project (which isn’t posted yet) is an attempt to turn a C.H.I.P into an Amazon Echo, for which [B Arnold] needed an audio amplifier. Turning to the junk bin, he unearthed an LM386, that venerable power amp chip that first appeared in the mid-70s. Dead simple and able to run off a 9-volt battery, the LM386 that has found its way into thousands of commercial products and countless hacks.

Shortly after applying power to the amp, [B Arnold] started hearing things – faint, far-off voices, scratchy but discernible. A bit of repositioning of wires and hands improved the signal enough for a station ID – an FM talk radio station on 97.1 MHz. [B Arnold] doesn’t mention the call sign, but it might have been KFTK out of St. Louis, Missouri; in any case, it would be helpful to know the range from the transmitter to the inadvertent receiver. Two low-fidelity audio clips are included below for your listening pleasure – you’ll want your headphones on, and Sample 2 is better than Sample 1 – as are photos of the offending circuit.

What do you think is going on here? We’ve heard of RF coupling of AM radio stations before, but how would FM signals be making it into this circuit and out of the speaker? Is there anything [B Arnold] did wrong to get this result? Sound off in the comments and let us know your horror stories of RF coupling.

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Creepy Wireless Stalking Made Easy

In a slight twist on the august pursuit of warwalking, [Mehdi] took a Raspberry Pi armed with a GPS, WiFi, and a Bluetooth sniffer around Bordeaux with him for six months and logged all the data he could find. The result isn’t entirely surprising, but it’s still a little bit creepy.

If your WiFi sends out probe requests for its home access points, [Mehdi] logged it. If your Bluetooth devices leak information about what they are, [Mehdi] logged it. In the end, he got nearly 30,000 WiFis logged, including 120,000 probes. Each reading is timestamped and geolocated, and [Mehdi] presents a few of the results from querying the resulting database.

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Hackaday Links: December 4, 2016

The Chaos Communication Congress is growing! Actually, it’s not, but there may be an ‘overflow venue’ for everyone who didn’t get a ticket. There’s a slack up for people who didn’t get a ticket to 33C3 but would still like to rent a venue, set up some tables, stream some videos, and generally have a good time.

Need to test a lot of batteries? Have one of those magnetic parts tray/dish things sitting around? This is freakin’ brilliant. Put your batteries vertically in a metal dish, clip one lead of a meter to the dish and probe each battery with the other lead of your meter.

Pravda reports the USS Zumwalt and HMS Duncan – the most technologically advanced ships in the US and Royal Navies – have turned into, ‘useless tin cans due to China’, with ‘Microchips made in China putting the vessels out of action’. Again, Pravda reports this, so don’t worry. In other news, someone found a few USB drives in a parking lot in Norfolk, Virginia.

Here’s how discourse goes on the Internet. Someone does something. Everyone says it’s stupid. We wait a few days or weeks. Someone posts something on Medium telling everyone it’s actually okay. Public opinion is muddled until the actual issue being discussed is rendered technologically irrelevant. For the newest MacBook Pro, we’re currently at stage 3 and ‘it’s kind of great for hackers’. Now if only we knew how to make USB-C ports work with microcontrollers…

If you have a Prusa i3, here’s a free gift: a Spitfire. The files to print a remote control, 973mm Spitfire Mk XVI are now free for Prusa i3 and i3 Mk 2 owners. Why? Because it’s cool, duh, and [Stephan Dokupil] and [Patrik Svida], the guys behind the Spitfire and other 3D printed RC planes, are also in Czech. Now all we need are Czech roundel stickers.

NASA Wants SpacePoop Hackers

NASA is looking for a few good men and women to solve an upcoming problem. Astronauts will soon be venturing outward beyond Earth orbit. If the spacecraft cabin should depressurize then they’ll have to put on their spacesuits and may have to keep them on for up to six days. During that time something will have to handle the resulting urine, fecal, and menstrual waste, all without the astronauts use of their hands. And that’s where you come in.

NASA is having a space poop challenge. The current system of an adult diaper won’t last six days. Your job, should you choose to accept it, is to design a system that will move the waste away from the skin where it can cause infection. Continue reading for the rather unique requirements.

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Repurpose A Classroom Clicker For Great Justice

If you’ve been in a university class of a certain size, with a professor who wants to get live feedback from the students, you’ve probably been forced to buy a Turning Point “clicker”. Aside from the ridiculousness of making students pay for their professor’s instructional aides (do the make you pay extra for the chalk too?!?!) these clickers are a gauntlet thrown down to any right-minded hacker because they supposedly contain secrets.

[Nick] had one of these gadgets, and hopped right up on the shoulders of giants to turn it into a remote control that interfaces with his computer and drives a synthesizer, so he can work through the chord changes by clicking. His two references, to [Travis Goodspeed]’s nRF promiscuity hack and to [Taylor Killian]’s Arduino library for the clickers are a testament to why we need both reverse engineers doing the hard work and people who’ll wrap up the hard work in an easy-to-use library.

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Otto Bot Is Bob’s Grandson

The Otto DIY robot has just taken first place in the coveted role as “best robot to 3D print for your (inner) child”. It’s cute, it dances, it doesn’t cost too much, it’s completely open source, and it’s not impossible to write code for. It’s probably the most refined Bob design that we’ve seen yet. Watch it move in the video below.

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Replacing A Failed Ebook Reader Battery

Resurrecting a beloved piece of tech can be a trying process when fighting through the mild heartbreak — doubly so if the product has been discontinued. When their old Sony PRS-T1 e-book reader refused to charge after leaving it on their dashboard during a hot day, [Andrea Gangemi] decided to leverage a little techno-necromancy and hack together a fix.

[Gangemi] found the problem to be a battery failure, but there was nary a replacement to be found. An old Motorola mobile phone battery ended up fitting the purpose nicely. Cracking open the e-book reader, de-soldering the old battery and — after deciphering which pins were which — installing the new one was simply done with a fine, high temperature soldering iron tip and Kapton tape to avoid short-circuiting. But hold on — the new battery wouldn’t charge, and the reader displayed a message saying that the battery was over heating; irony, thou art cruel.

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