Month: June 2019

Unconventional Drone Uses Gas Thrusters For Control

June 8, 2019 by 28 Comments

You’ve got to hand it to [Tom Stanton] – he really thinks outside the box. And potentially outside the atmosphere, to wit: we present his reaction control gas thruster-controlled drone.

Before anyone gets too excited, [Tom] isn’t building drones for use in a vacuum, although we can certainly see a use case for such devices. This is more of a hybrid affair, with counter-rotating props mounted in a centrally located duct providing the lift and the yaw control. Flanking that is a triangular frame supporting three two-liter soda bottle air reservoirs, each of which supplies a down-firing nozzle at each apex of the triangle. Solenoid valves control the flow of compressed air from the bottles to the nozzles, providing thrust to stabilize the roll and pitch axes. As there aren’t many off-the-shelf flight control systems set up for reaction control, [Tom] had to improvise thruster control; an Arduino watches the throttle signals normally sent to a drone’s motors and fires the solenoids when they get to a preset threshold. It took some tuning, but [Tom] was eventually able to get a stable, untethered hover. And he’s right – the RCS jets do sound amazing when they’re firing, as long as the main motors are off.

This looks as though it has a lot of potential, and we’d love to see it developed more. It reminds us a bit of this ducted-prop drone, another great example of stretching conventional drone control concepts to the limit.

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Play To The Beat Of This Robotic Drummer In A Box

June 8, 2019 by 1 Comment

No drummer? No problem! With a little ingenuity, you can stuff the essentials of a drum kit into a box, and automate your rhythm section.

Mind you, [Franco Molina]’s “DrumCube” doesn’t quite have the flash of a human drummer, but it does keep a steady beat and has a charm of its own. The drum machine is mostly mechanical, reminding us somewhat of the Wintergatan Marble Machine which is as captivating to watch as it is to hear. The DrumCube has a snare drum played by two servo-controlled sticks, a kick drum using foam waggled back and forth between two piezo transducers hooked to a low-pass filter, and a reverse-biased transistor white noise generator used for the hi-hat. Sadly, the large gear appears to be just for show. An Arduino runs everything and makes sure the mechanical drum hits are synced to the electronic cymbals, which was no mean feat.

The video below shows it in action accompanying [Franco] on his guitar, and it looks as good as it sounds. Prefer a more compact, all-electronic drum kit? Here’s one that fits in your pocket.

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Panadaptors Didn’t Start With SDRs

June 8, 2019 by 6 Comments

The must-have accessory on a modern all-singing, all-dancing amateur radio transceiver is a panadaptor. Inevitably driven by SDR technology, it’s a view of a band in the frequency domain, and it will usually be displayed as a “waterfall” giving a time dimension to see transmissions over a period.

[Bill Meara, N2CQR] reminds us that panadaptors are nothing new, indeed that they date back to the first half of the last century and don’t even need an SDR to work. And to prove it, he’s produced one for part of the 40-metre amateur band.

The principle behind an analogue panadaptor is simple enough, it’s a normal receiver whose local oscillator is given a linear periodic sweep over the desired frequency band and whose output drives the Y axis of an oscilloscope whose X axis is driven by the sweep. In [Bill]’s case the receiver is a BitX homebrew transceiver, and the swept local oscillator is provided by his Foeltech signal generator. A neat touch comes in the ‘scope being synchronised by triggering on a marker frequency at the bottom of the range being swept. He’s created a video showing it in action, which you can see below the break.

There are quite a few routes into making this type of simple spectrum analyser, indeed some of us have tried ti with TV tuners.

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1980s Plotter Plays Flappy Bird

June 8, 2019 by 5 Comments

Should you happen to have an HP7440A or similar plotter hanging around, you could have a quick game of Flappy Bird — or Plotty Bird as [WesleyAC] calls it. Just be sure you have some blank paper. The whole thing fits in about 200 lines of Rust code and — according to the author — gets to about 20 frames per second.

Watching the thing go, it appears that it draws a random set of pipes and then traces your flight path on the same page in real time.

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C++ Reverbs From A Matlab Design

June 8, 2019 by 6 Comments

The guitar ‘Toing’ sound from the ’70s was epic, and for the first time listener it was enough to get a bunch of people hooked to the likes of Aerosmith. Reverb units were all the rage back then, and for his DSP class project, [nebk] creates a reverb filter using Matlab and ports it to C++.

Digital reverb was introduced around the 1960s by Manfred Schroeder and Ben Logan. The system consists of essentially all pass filters that simply add a delay element to the input signal and by clubbing a bunch together and then feeding them to a mixer. The output is then that echoing ‘toing’ that made the ’80s love the guitar so much. [Nebk]’s take on it enlists the help of the Raspberry Pi and C++ to implement the very same thing.

In his writeup, [nebk] goes through the explaining the essentials of a filter implementation in the digital domain and how the cascaded delay units accumulate the delay to become a better sounding system. He also goes on to add an FIR low pass filter to cut off the ringing which was consequent of adding a feedback loop. [nebk] uses Matlab’s filter generation tool for the LP filter which he includes the code for. After testing the design in Simulink, he moves to writing the whole thing in C++ complete with the filter classes that allows reading of audio files and then spitting out ‘reverbed’ audio files out.

The best thing about this project is the fact that [nebk] creates filter class templates for others to play with. It allows those who are playing/working with Matlab to transition to the C++ side with a learning curve that is not as steep as the Himalayas. The project has a lot to learn from and is great for beginners to get their feet wet. The code is available on [GitHub] for those who want to give it a shot and if you are just interested in audio effects on the cheap, be sure to check out the Ikea Reverb Plate that is big and looks awesome.

Maker Media Ceases Operations

June 7, 2019 by 200 Comments

Over the years we’ve had the dubious honor of bidding farewell to numerous companies that held a special place in the hearts of hackers and makers. We’ve borne witness to the demise of Radio Shack, TechShop, and PrintrBot, and even shed a tear or two when Toys “R” Us shut their doors. But as much as it hurt to see those companies go, nothing quite compares to this. Today we’ve learned that Maker Media has ceased operations.

Between the first issue of Make magazine in 2005 and the inaugural Maker Faire a year later, Maker Media deftly cultured the public face of the “maker movement” for over a decade. They didn’t create maker culture, but there’s no question that they put a spotlight on this part of the larger tech world. In fact, it’s not an exaggeration to say that the shuttering of Maker Media could have far reaching consequences that we won’t fully understand for years.

While this news will surely come as a crushing blow to many in the community, Maker Media founder and CEO Dale Dougherty says they’re still trying to put the pieces together. “I started the magazine and I’m committed to keeping that going because it means something to a lot of people and means something to me.” At this point, Dale tells us that Maker Media is officially in a state of insolvency. This is an important distinction, and means that the company still has a chance to right the ship before being forced to declare outright bankruptcy.

In layman’s terms, the fate of Make magazine and Maker Faire is currently uncertain. The intent is to restructure the organization and rehire enough people to keep the brand alive, but it may take rethinking their business model entirely. While they aren’t looking to crowdsource the resurrection of Make, Dale said he believes the answer may ultimately come from the community’s willingness to financially support them, “my question is can we perhaps rely on the community to offer support for what we’re doing in ways we have not asked for in the past.” Ideas currently being discussed include the sort of annual membership and pledge drives used by public broadcasting.

It’s impossible to overstate the positive influence that Make has had on the public’s perception of DIY. It put on a global pedestal the sort of projects which otherwise might have never been seen outside the basement workshops or garages they were constructed in. Through their events and outreach programs, Make showed an entire generation of young people that building something just for the joy of building it was something to be proud of. Make proved that nerds could be cool in a way that had never been done before, and worryingly, may never be done again. Let’s take a look at that legacy.

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Tap ‘N Ghost: A Novel Attack Against Smartphone Touchscreens

June 7, 2019 by 13 Comments

Researchers have demonstrated a new vulnerability in NFC, a feature built-in to many smartphones sold today. The vulnerability allows the attacker to to generate ‘ghost taps’ against a device, effectively allowing an attacker to tap your phone without you looking.

The 18-page paper released by a team of three researchers based out of Waseda University in Japan consists of two techniques: an attack against NFC-enabled smartphones and an attack against capacitive touchscreens. It should be noted that nearly all phones have NFC, and nearly every phone released in the last decade has a capacitive touchscreen. Vunlnerable devices include, but are not limited to the Xperia Z4, the Galaxy S6 Edge, the Galaxy S4, Aquos Zeta SH-04F, Nexus 9, and Nexus 7.

The experimental setup consists of a signal generator, high-speed bipolar amplifier, a small transformer (taken from a toy plasma ball), a copper sheet, oscilloscope with high-voltage probe, and an NFC card emulator. No other special equipment is required. When the victim places their smartphone on a table top, the phone is fingerprinted, giving the attacker the make and model of phone. A dialog box then pops up and the phone connects to a network.

This attack can be replicated by anyone, and the tools required are simple and readily available. The mitigation is to disable NFC on your phone.

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