A Cold Gas Thruster On An RC Car

August 15, 2021 by 12 Comments

Tesla have boldly claimed that one day they’ll ship a Roadster complete with a cold-gas thruster for truly ridiculous acceleration. Whether or not that ever comes to pass remains to be seen, but [Engineering After Hours] decided to try out the technology on an RC car instead.

The thruster uses a pair of disposable CO2 canisters to deliver 1770 g of thrust via a converging-diverging nozzle. Actuated by servos and a simple valve, the system dumps the high-pressure CO2 to help accelerate the car up to speed. Paired with sticky tires and a powerful brushless motor, the plan was to try and beat Tesla’s claimed 1.1 second 0-60mph acceleration figure for the thruster-boosted roadster.

Unfortunately, the high center of gravity of the RC car led to stability issues, largely due to the mounting of the thruster itself. Additionally, the high weight of the car – around 4.3kg – meant that at best, the thruster would only add 0.5g to the vehicle’s acceleration.

While the car didn’t net a quick 0-60 time, it’s still neat to see a cold gas thruster on an RC car. It may not have been a Tesla-beater like some earlier projects, but it was cool all the same. Video after the break.

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Solar Fueled Emergency Power Pack

August 15, 2021 by 23 Comments

Heavy rainfall in Northern Europe last month caused disastrous flooding in several countries. [Daniel Jedecke] was on assignment in the North Rhine-Westphalia region of Germany during the floods and saw the damage firsthand. He was struck by the lack of emergency power, and set about the task of designing a simple, portable power pack.

[Daniel] wanted his system to be as simple and maintenance-free as possible, and well as inexpensive. He passed by the traditional solutions such as gasoline fueled generators or advanced chemistry battery packs. Instead, he settled on the ordinary car battery — they’re easy to obtain in a pinch, and he found a used 45 Ah one sitting in his basement. To keep the system portable, he decided on a single 80 W monocrystalline solar panel which comes with a smart battery charge controller. An inverter provides standard (for Germany) 240 VAC in addition to the +12 VDC output.

The whole thing, except the panel, is installed in an off-the-shelf toolbox with the pieces secured to a custom-made wood frame. We think [Daniel]’s goals were met: made from standard materials, long-lasting without excessive maintenance, portable, and providing both DC and AC outputs for everyday use. Way back in 2015 we wrote about an emergency battery pack using rechargeable drill batteries. Do you keep an emergency power pack handy in case of outages or disasters?

3D Printed Fabric Stiffens On Demand

August 15, 2021 by 20 Comments

Researchers in Singapore and at CalTech have developed a 3D printed fabric with an interesting property: it is generally flexible but can stiffen on demand. You can see a video about the new fabric, below.

The material consists of nylon octahedrons interlocked. The cloth is enclosed in a plastic envelope and vacuum-packed. Once in a vacuum, the sheet becomes much stiffer and can hold many times its own weight.

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Touchscreen Makes For A Neat Wavetable Synth

August 15, 2021 by 8 Comments

A popular tool in chiptune software like LSDJ allows the user to draw a waveform and use it as the basis for a wavetable synth. It’s fun and it can produce some great bleeps and bloops. [Kevin] has created a similar tool using an Arduino and a touchscreen.

You can draw the waveform! That’s neat.

The build is based on the Arduino Uno, the humble mainstay of the Arduino line. It’s hooked up to an ILI9488 color touchscreen display, which acts as the primary user interface. Using a stylus, or presumably a finger, the user can draw directly on the screen to specify the desired waveform for the synth to produce. The Arduino reads the step-by-step amplitude values of the drawn waveform and uses them to synthesize audio according to MIDI messages received over its serial port. Audio output is via PWM, as is common in low-cost microcontroller projects.

It’s a fun build and we’re sure [Kevin] learned plenty about wavetable synthesis along the way. We’ve seen his work on other Arduino synthesis projects before, too! Video after the break.

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Yo Dawg, We Heard You Like Retrocomputers

August 14, 2021 by 20 Comments

The idea of having software translation programs around to do things like emulate a Super Nintendo on your $3000 gaming computer or, more practically, run x86 software on a new M1 Mac, seems pretty modern since it is so prevalent in the computer world today. The idea of using software like this is in fact much older and easily traces back into the 80s during the era of Commodore and Atari personal computers. Their hardware was actually not too dissimilar, and with a little bit of patience and know-how it’s possible to compile the Commodore 64 kernel on an Atari, with some limitations.

This project comes to us from [unbibium] and was inspired by a recent video he saw where the original Apple computer was emulated on Commodore 64. He took it in a different direction for this build though. The first step was to reformat the C64 code so it would compile on the Atari, which was largely accomplished with a Python script and some manual tweaking. From there he started working on making sure the ROMs would actually run. The memory setups of these two machines are remarkably similar which made this slightly easier, but he needed a few workarounds for a few speed bumps. Finally the cursor and HMIs were configured, and once a few other things were straightened out he has a working system running C64 software on an 8-bit Atari.

Unsurprisingly, there are a few things that aren’t working. There’s no IO besides the keyboard and mouse, and saving and loading programs is not yet possible. However, [unbibium] has made all of his code available on his GitHub page if anyone wants to expand on his work and may also improve upon this project in future builds. If you’re looking for a much easier point-of-entry for emulating Commodore software in the modern era, though, there is a project available to run a C64 from a Raspberry Pi.

Thanks to [Cprossu] for the tip!

Making Ferroelectric Solar Cells Better

August 14, 2021 by 17 Comments

Researchers claim that using several very thin layers of ferroelectric crystals can lead to significantly better ferroelectric solar cell efficiency. But don’t pull the panels off your roof yet. Conventional cells are still much more efficient than ferroelectric devices — at least, for now.

Unlike conventional silicon-based solar cells, ferroelectric cells don’t depend on a PN junction and — in theory — can be cheaper and easier to produce. However, they typically don’t absorb as much sunlight as other materials.

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3D Printed Smart Glasses Put Linux In Your Face

August 14, 2021 by 20 Comments

Unimpressed by DIY wearables powered by dinky microcontrollers, [Teemu Laurila] has been working on a 3D printed head-mounted computer that puts a full-fledged Linux desktop in your field of view. It might not be as slim and ergonomic as Google Glass, but it more than makes up for it in terms of raw potential.

Featuring an overclocked Raspberry Pi Zero W, a ST7789VW 240×240 IPS display running at 60 Hz, and a front-mounted camera, the wearable makes a great low-cost platform for augmented reality experiments. [Teemu] has already put together an impressive hand tracking demonstration that can pick out the position of all ten fingers in near real-time. The processing has to be done on his desktop computer as the Zero isn’t quite up to the task, but as you can see in the video below, the whole thing works pretty well.

Precision optics, courtesy of a hacksaw

Structurally, the head-mounted unit is made up of nine 3D printed parts that clip onto a standard pair of glasses. [Teemu] says the parts will probably need to be tweaked to fit your specific frames, but the design is modular enough that it shouldn’t take too much effort. He’s using 0.6 mm PETG plastic for the front reflector, and the main lens was pulled from a cheap pair of VR goggles and manually cut down into a rectangle.

The evolution of the build has been documented in several videos, and it’s interesting to see how far the hardware has progressed in a relatively short time. The original version made [Teemu] look like he was cosplaying as a Borg drone from Star Trek, but the latest build appears to be far more practical. We still wouldn’t try to wear it on an airplane, but it would hardly look out of place at a hacker con.

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