Hackaday Podcast 103: Antennas For Everyone, A Clock Made Of Chains, Magic Eye Tubes, And A Little Google Bashing

January 29, 2021 by 2 Comments

Hackaday editors Mike Szczys and  Elliot Williams discuss the greatest hacks of the week that was. Antennas aren’t rocket science, so this week we really enjoyed a video that demystifies antenna designs and a project that tunes up the antennas on cheap wireless modules in the simplest of ways. Google’s in the news this week with the end to project Loon, and a dust-up with the volunteer package maintainers who have spent years making sure Chromium browser is in the Linux repos. Elliot is gaga for magic eye tubes and crazy musical instruments, while Mike is over the moon for a chain-based clock display. We close up the episode talking about the Concorde, and the math behind cable mechanisms.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

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The Last Few Analogue TV Stations In North America

January 29, 2021 by 40 Comments

Analogue TV is something that most of us consider to have been consigned to the history books about a decade ago depending on where in the world we are, as stations made the transition to much more power and frequency efficient digital multiplexes. However some of them still cling on for North American viewers, and [Antenna Man] took a trip to Upstate New York in search of some of them before their final switch-off date later this year.

What he reveals can be seen in the video below the break, an odd world of a few relatively low-power analogue TV stations still serving tiny audiences, as well as stations that only exist because their sound carrier can be picked up at the bottom of the FM dial. These stations transmit patterns or static photographs, with their income derived from the sound channel’s position as an FM radio station. While his journey is an entertaining glimpse into snowy-picture nostalgia it does also touch on some other aspects of the aftermath of analogue TV boradcasting. The so-called “FrankenFM” stations sound much quieter, we’re guessing because of the lower sound carrier deviation of the CCIR System M TV spec compared to regular FM radio. And we’re told that there are more stations remaining in Canada, so get out there if you still want to see an analogue picture before they’re gone forever. Where this is being written the switch to DVB was completed in 2013, and it’s still a source of regret that we didn’t stay up to see the final closedown.

Does your country still have an analogue TV service? Tell us in the comments.

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This Week In Security: Sudo, Database Breaches, And Ransomware

January 29, 2021 by 27 Comments
We couldn't resist, OK?
Obligatory XKCD

Sudo is super important Linux utility, as well as the source of endless jokes. What’s not a joke is CVE-2021-3156, a serious vulnerability around incorrect handling of escape characters. This bug was discovered by researchers at Qualys, and has been in the sudo codebase since 2011. If you haven’t updated your Linux machine in a couple days, you may very well be running the vulnerable sudo binary still. There’s a simple one-liner to test for the vulnerability:

sudoedit -s '\' `perl -e 'print "A" x 65536'`

In response to this command, my machine throws this error, meaning it’s vulnerable:

malloc(): corrupted top size
Aborted (core dumped)

To understand the problem with sudo, we have to understand escape characters. It really boils down to spaces in file and folder names, and how to deal with them. You want to name your folder “My Stuff”? That’s fine, but how do you interact with that directory name on the command line, when spaces are the default delimiter between arguments? One option is to wrap it in quotation marks, but that gets old in a hurry. The Unix solution is to use the backslash character as an escape character. Hence you can refer to your fancy folder as My\ Stuff. The shell sees the escape character, and knows to interpret the space as part of the folder name, rather than an argument separator. Escape characters are a common vulnerability location, as there are plenty of edge cases. Continue reading “This Week In Security: Sudo, Database Breaches, And Ransomware” →

Fire In The Palm Of Your Hand

January 29, 2021 by 15 Comments

For as long as super-heroes have existed, they have inspired hacker projects. For [Everett Bradford], emulating the character Pyro from X-Men has been an on and off project for the last decade. His latest version, Pyro System V4, integrates quite a bit of control electronics to give the rather convincing effect of mind-controlled fire in the palm of his hand. (Video, embedded below.)

The system is a motor-actuated slider strapped to [Everett]’s forearm, which pushes a pivoting end-effector with an integrated butane burner into the palm of his hand. The slider runs on 4 mm linear bearings actuated by a small geared DC motor using cables. The end effector is spring-loaded to push it into the palm and integrates a high voltage ignition arc generator circuit, nozzle, and capacitive activation button.

The butane gas canister and the valve was cannibalized from a small blow torch lighter, and the valve is actuated by another geared DC motor. The valve actuator, slide actuator, and end-effector hinge all integrate position feedback via hall effect sensors and magnets. The sensor in the hinge allows the slide to actively correct for the angle of the user’s wrist, keeping the end effector in the middle of the palm.

The control circuit is split into two parts. One PIC16 microcontroller runs all the motion control and position sensing, while a PIC18 connected to a small touch screen handles user interface, control parameters, and ignition. The touch screen proved especially useful for control parameters during development without needing to connect to a laptop.

Some of [Everett]’s previous version had a much more impressive (and dangerous) flame but was also very bulky. We think this latest version strikes a pretty good balance regarding compactness and achieving convincing illusion.

[Colin Furze] is another name commonly associated with fire-breathing contraptions, but they have a proven history of landing him in hospital.

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A Look At The Interesting RP2040 Peripheral, Those PIOs

January 29, 2021 by 41 Comments

The Raspberry Pi Pico is the latest product in the Raspberry Pi range, and it marks a departure from their previous small Linux-capable boards. The little microcontroller board will surely do well in the Pi Foundation’s core markets, but its RP2040 chip must have something special as a commercial component to avoid being simply another take on an ARM microcontroller that happens to be a bit more expensive and from an unproven manufacturer in the world of chips. Perhaps that special something comes in its on-board Programable IO perhipherals, or PIOs. [CNX Software] have taken an in-depth look at them, which makes for interesting reading.

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This Negative Reinforcement Keyboard May Shock You

January 28, 2021 by 23 Comments

We wouldn’t be where we are today without Mrs. Coldiron’s middle school typing class. Even though she may have wanted to, she never did use negative reinforcement to improve our typing speed or technique. We unruly teenagers might have learned to type a lot faster if those IBM Selectrics had been wired up for discipline like [3DPrintedLife]’s terrifying, tingle-inducing typist trainer keyboard (YouTube, embedded below).

This keyboard uses capsense modules and a neural network to detect whether the user is touch-typing or just hunting and pecking. If you’re doing it wrong, you’ll get a shock from the guts of a prank shock pen every time you peck the T or Y keys. Oh, and just for fun, there’s a 20 V LED bar across the top that is supposed to deter you from looking down at your hands with randomized and blindingly bright strobing light.

Twenty-four of the keys are connected in groups of three by finger usage — for example Q, A, and Z are wired to the same capsense module. These are all wired up to a Raspberry Pi Zero along with the light bar. [3DPrintedLife] was getting a lot of cross-talk between capsense modules, so they solved the problem in software by training a TensorFlow model with a ton of both proper and improper typing data.

We love the little meter on the touchscreen that shows at a glance how you’re doing in the touch typing department. As the meter inches leftward, you know you’re in for a shock. [3DPrintedLife] even built in some games that use pain to promote faster and more accurate typing. Check out the build video after the break, but don’t say we didn’t warn you about the strobing lights.

The secret to the shock pen is a tiny flyback transformer like the kind used in CRT televisions. Find a full-sized flyback transformer and you can build yourself a handheld high-voltage power supply.

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Controlling A Quadcopter With One Dead Motor

January 28, 2021 by 17 Comments

Quadcopters have incredible flying abilities, but if one loses just a single motor, it drops like a rock. Researchers from the University of Zurich’s Robotics and Perception Group have proven that this does not need to be the case by keeping a quadcopter flying with only three motors.

A quadcopter usually has enough thrust to stay aloft with only three motors, but it will spin uncontrollably in the yaw axis. It is impossible to stop a quadcopter from spinning, so the focus for researchers was on keeping the drone controllable while it’s spinning. To achieve this, accurate position and motion estimation is required, so they attached a pair of cameras to the bottom of the craft for visual-inertial odometry (VIO). One is a normal optical camera, while the other is an event camera, which has pixels that can independently respond to changes in light as they occur. This means that it has better low light performance and does not suffer from motion blur.

The feeds from the cameras are analyzed in real-time by an onboard Nvidia Jetson TX2 for state estimation, which is then used with an optical range sensor and onboard IMU to maintain controlled flight, as demonstrated in the video after the break. The research paper is free to read, and all the code is available on GitHub.

New developments in drone control schemes are always fascinating, like this hexacopter with an innovative motor layout to achieve six degrees of freedom, or a conventional helicopter with a virtual swash plate.
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