Light Painting With An 19th Century Inspired Plotter

The geometric chuck was a device that stacked up multiple rotating wheels that could vary their speed and their offset to a central shaft, in order to machine ornate designs using a lathe. It’s this piece of machining obscura from the 19th century that inspired this light painting build from [Ted Kinsman].

Rather than the complicated gears and wheels used in the distant past, [Ted] instead elected to use stepper motors. Three stepper motors are stacked on top of each other, each one able to rotate at an independent rate. The design only implements three steppers as the slip rings needed to send power and control signals to each stepper are prohibitively expensive.

An Arduino is programmed to run the show, changing the speed of each motor and thus the patterns the system generates. Put LEDs on the spinning plates, or install a pen to mark a piece of paper, and it’s possible to generate all manner of beautiful spirograph-like patterns. Vary the motor speeds or the positioning of the lights, and the patterns vary in turn.

It’s a fun build for light painting, with some great visuals produced. We also appreciate the use of the Arduino which makes varying the parameters far easier than having to change out gearsets in classical designs.

If you miss the old school spirograph, you can always build one out of Lego. Else, consider experimenting with other light painting techniques. If you’ve built a fancy rig of your own, be sure to let us know!

[Thanks to zit for the tip!]

Robot Pet Is A Chip Off The Old Logic Block

When [Ezra Thomas] needed inspiration for his senior design project, he only needed to look as far as his own robot. Built during his high school years from the classic 1979 Frank DaCosta book “How to Build Your Own Working Robot Pet”, [Ezra] had learned the hard way the many limitations and complexities of the wire wrapped 74xx series logic chips surrounding its 8085 processor.

[Ezra] embarked on a quest to recreate the monstrosity in miniature, calling it Pet on a Chip. Using a modern FPGA chip allows the electronics to shrink by an order of magnitude and provides flexibility for future expansion. Implementing an 8 bit CPU on the amply sized FPGA left plenty of room for a VGA GPU, motor controller, serial UART, and more. Programming the CPU is handled by a custom assembler written in Python.

The results? Twelve times less weight, thirteen times less power draw, better performance, and a lot of room for growth. [Ezra] hints at an I2C bus expansion as well as a higher level programming language to make software development less of a hurdle.

The Pet On A Chip is a wonderfully engineered project and we hope that we’ll be seeing more such from [Ezra] as time goes by. Watch his Pet On A Chip in action in the video below the break.

If [Ezra]’s FPGA escapades have you wondering how to get started, you can check out this introduction to FPGA from the 2019 Hackaday Superconference. And if you have your own FPGA creation to share, please let us know via the Tip Line!

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Hackaday Links: August 15, 2021

Unless you’re in the market for a new car, household appliance, or game console, or if you’re involved in the manufacture of these things, chances are pretty good that the global semiconductor shortage hasn’t directly impacted you yet. But we hobbyists might be due for a comeuppance as the chip shortage starts to impact our corner of the market. We suppose it’s natural that supplies of the chips needed to build Arduinos and Raspberry Pis would start to dry up, as semiconductor manufacturers realign their resources to service their most lucrative markets. Still, it was all sort of abstract until now, but seeing dire quotes from the likes of Adafruit, Pololu, and Sparkfun about the long lead times they’re being quoted — some chips won’t be seen until 2023! — is disheartening. As are the reports of price gouging and even hoarding; when a $10 part can suddenly command $350, you know something has gone seriously wrong.

But have no fear — we’re certain the global chip shortage will have no impact on the planned 2027 opening of the world’s first space hotel. Voyager Station — once dubbed Von Braun Station but renamed for some reason — looks for all the world like Space Station V in “2001: A Space Odyssey”, or at least half of it. The thing is enormous — witness the Starship docked in the center hub, as well as the several dozen shuttle-like craft — escape pods, perhaps? — attached to the outer rim. The renders are imaginative, to say the least — the station looks very sleek, completely unfettered by such banalities as, say, solar panels. We get that a private outfit needs to attract deep-pocketed investors, and that one doesn’t do that by focusing on the technical details when they can sell a “premium experience”. But really, if you’re going to space, do you want basically the same look and feel as a premium hotel on Earth, just with a better view? Or would you rather feel like you’ve actually traveled to space?

Speaking of space, did you ever wonder what the first programmable calculator in space was? Neither did we, but that doesn’t mean we didn’t find this detailed story about the HP-65 that was sent up on the Apollo-Soyuz Test Project in 1975 pretty fascinating. The ASTP was the last hurrah of Apollo, and an often underappreciated engineering challenge. Linking up the two spacecraft safely was not trivial, and a fair number of burn calculations had to be made in orbit to achieve rendezvous and docking, as well as to maintain orbit. The HP-65, a programmable calculator that went for about $750 at the time (for the non-space-rated version, of course) had several programs loaded onto its removable magnetic cards, and the Apollo crew used it to verify the results calculated by the Apollo Guidance Computer (AGC).

Facebook, a company that exists by providing people with a product they don’t need but now somehow can’t live without, is now dipping a toe into weird, weird waters: reverse-passthrough virtual reality. The idea, we take it, is that as users more widely adopt VR and integrate it into their daily lives, the VR headsets everyone will be wearing will make face-to-face contact more difficult. So what better way to solve that problem than by projecting a live image of the VR user’s eyes onto a screen outside the VR rig, for any and all to see? Pure genius, and not the least bit creepy. They’ve perhaps got a bit of work to go before achieving their goal of “seamless social connection between real and virtual worlds”.

And speaking of eyes, it’s good to know that developers are still hard at work keeping the most vital applications running at peak efficiency on today’s hardware. Yes, the venerable XEyes, a program for the X Window System on Unix-like operating systems that draws a pair of googly eyes on the screen to follow your mouse movements, has finally moved to version 1.2.0. It’s been 11 years since the 1.1.0 upgrade, so it was a long time coming. If you haven’t had the chance to play with XEyes, fear not — just about any Linux machine should be able to show you what you’ve been missing. Or, you know, you could even run it on a camera as the video below the break shows.

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Solar Display Case Is A Portable Triple Monitor Setup

They say once you start using twin monitors on the desktop, you’ll never want to go back. It’s even worse when you upgrade to three or more. However, it can be difficult to take such a set up on the road. Desiring better productivity on the go is what spurred [Brian Whitsett] to develop the Solar Display Case to solve this problem.

The Solar Display Case aims to pack three 17″ full-size monitors into a portable waterproof case. Brian has already built a prototype, which puts the monitors on folding arms so that they can be quickly stowed or deployed when needed.

The build also relies on solar power to charge batteries, in order to make the solution as portable as any laptop or other hardware you may be using with it. It’s no good having three mains-powered monitors sitting in the field with no AC power, after all. [Brian] aims to use a flexible solar panel to make the most of the surface area of the deployed assembly, for maximum power generation.

It’s a great project, and one we’d love to see fleshed out to the fullest. Imagining a briefcase that folds out into a triple-monitor workstation is exciting, and it looks like [Brian] is well on the way to making it a reality.

A Cold Gas Thruster On An RC Car

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

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

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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