There’s been a lot of news lately about the Long Now Foundation and Jeff Bezos spending $42 million or so on a giant mechanical clock that is supposed to run for 10,000 years. We aren’t sure we really agree that it is truly a 10,000 year clock because it draws energy — in part — from people visiting it. As far as we can tell, inventor Danny Hills has made the clock to hoard energy from several sources and occasionally chime when it has enough energy, so we aren’t sure how it truly sustains itself. However, it did lead us to an interesting question: how could you design something that really worked for 10,000 years?
It’s hard not to be impressed by the Arduboy. In just a few short years, [Kevin Bates] went from proof of concept to a successful commercial product without compromising on his original open source goals. Today, anyone can develop a game for the Arduboy and have it distributed to owners all over the world for free. If you’ve ever dreamt of being a game developer, the Arduboy community is for you.
Realizing the low-cost hardware and open source software of the Arduboy makes it an excellent way to learn programming, [Kevin] is now trying to turn his creation into a legitimate teaching tool. He’s kicking off this new chapter in the Arduboy’s life with a generous offer: giving out free hardware to educators all over the world. Anyone who wants to be considered for the program just needs to write-up a few paragraphs on how they’d utilize the handheld game system in their class.
[Kevin] already knows the Arduboy has been used to teach programming, but those have all been one-off endeavours. They relied on a teacher that was passionate enough about the Arduboy to put in their own time and effort to create a lesson plan around it. So one of the main goals right now is getting an official curriculum put together so educators won’t have to start from scratch. The community has already developed 16 free lessons, but they’re looking for help in creating more and translating them into other languages.
While the details are still up in the air, [Kevin] also plans to travel to schools personally and help them get their Arduboy classes off the ground. He’s especially interested in developing countries and other areas that are disadvantaged educationally. Believing that the Arduboy is as much a way to teach effective leadership and teambuilding as it is programming, he thinks this program can truly make a difference.
Spaceflight is inherently dangerous. It takes a certain type of person to willingly strap into what’s essentially a refined bomb and hope for the best. But what might not be so obvious is that the risks involved aren’t limited to those who are personally making the trip. The construction and testing of space-bound vehicles poses just as much danger to engineers here on the ground as it does to the astronauts in orbit. Arguably, more so. Far more individuals have given their lives developing rocket technology than have ever died in the cockpit of one of them.
Reddish brown exhaust of hydrazine thrusters
Ultimately, this is because of the enormous amount of energy stored in the propellants required to make a rocket fly. Ground support personnel need to exercise great care even when dealing with “safe” propellants, such as the classic combination of kerosene and liquid oxygen. On the other end of the spectrum you have chemicals that are so unstable and toxic that they can’t be handled without special training and equipment.
One of the most dangerous chemicals ever used in rocket propulsion is hydrazine; and yet from the Second World War to the present day, it’s been considered something of an occupational hazard of spaceflight. While American launch vehicles largely moved away from using it as a primary propellant, hydrazine is still commonly used for smaller thrusters on spacecraft.
But soon, that might change. NASA has been working on a project they call the Green Propellant Infusion Mission (GPIM) which is specifically designed to reduce modern spacecraft’s dependency on hydrazine. In collaboration with the Air Force Research Laboratory at California’s Edwards Air Force Base, the space agency has spearheaded the development of a new propellant that promises to not just replace hydrazine, but in some scenarios even outperform it.
So what’s so good about this new wonder fuel, called AF-M315E? To really understand why NASA is so eager to power future craft with something new, we first have to look at the situation we’re in currently.
For whatever reason, the Video Graphics Array standard seems to attract a lot of hardware hacks. Most of them tend to center around tricking a microcontroller into generating the signals needed to send images to a VGA monitor. We love those hacks, but this one takes a different tack – a microcontroller-free VGA display that uses only simple logic chips and EEPROMs.
When we first spied this project, [PH4Nz] had not yet shared his schematics and code, but has since posted everything on GitHub. His original description was enough to whet our appetite, though. He starts with a 27.175-MHz clock and divides that by 4 with a 74HCT163, which has the effect of expanding the 160×240 pixels image stored in one of the EEPROMs to 640×480. Two 8-bit counters keep track of horizontal and vertical positions, while the other EEPROM takes care of generating the Hsync and Vsync signals. It’s all quite hackish, but it works. [PH4Nz] tells us that the whole thing is in support of a larger project: an 8-bit computer made from logic chips. We’re looking forward to seeing that one too.
Sometimes a hack isn’t about building something cool. Sometimes it’s more tactical, where the right stuff is cobbled together to gather the information needed to make decisions, or just to document some interesting phenomenon.
Take this impromptu but thorough exploration of basement humidity undertaken by [Matthias Wandel]. Like most people with finished basements in their homes, [Matthias] finds the humidity objectionable enough to warrant removal. But he’s not one to just throw a dehumidifier down there and forget about it. Seeking data on how well the appliance works, [Matthias] wired a DHT22 temperature/humidity sensor to a spare Raspberry Pi to monitor room conditions, and plugged the dehumidifier into a Kill-A-Watt with a Pi camera trained on the display to capture data on electrical usage.
His results were interesting. The appliance does drop the room’s humidity while raising its temperature, a not unexpected result given the way dehumidifiers work. But there was a curious cyclical spike in humidity, corresponding to the appliance’s regular defrost cycle driving moisture back into the room. And when the dehumidifier was turned off, room humidity gradually increased, suggesting an unknown source of water. The likely culprit: moisture seeping up through the concrete slab, or at least it appeared so after a few more experiments. [Matthias] also compared three different dehumidifiers to find the best one. The video below has all the details.
We always appreciate [Matthias]’ meticulous approach to problems like these, and his field expedient instrumentation. He seems to like his creature comforts, too – remember the target-tracking space heater from a few months back?
When you think of an old radio it’s possible you imagine a wooden-cased tube radio receiver as clustered around by a 1940s family anxious for news from the front, or maybe even a hefty 19-inch rack casing for a “boat anchor” ham radio transmitter. But neither of those are really old radios, for that we must go back another few decades to the first radios. Radio as demonstrated by Giulielmo Marconi didn’t use tubes and it certainly didn’t use transistors, instead it used an induction coil and a spark gap. It’s a subject examined in depth by [The Plasma Channel] and [Blueprint], as they come together to build and test a pair of spark gap transmitters.
This is a collaboration between two YouTube channels, so we’ve put videos from both below the break.They both build simple spark gap transmitters and explain the history behind them, as well as running some tests in RF-shielded locations. The transmitters are fairly crude affairs in that while they both use electronic drives for their induction coils they don’t have the resonant tank circuitry that a typical early-20th-century transmitter would have had to improve its efficiency.
They are at pains to remind the viewer that spark gap transmitters have been illegal for nearly a century due to their wideband interference so this is definitely one of those “Don’t do this at home” projects even if it hasn’t stopped others from trying. But it’s still a fascinating introduction to this forgotten technology, and both videos are definitely worth a watch.
Even though machine learning AKA ‘deep learning’ / ‘artificial intelligence’ has been around for several decades now, it’s only recently that computing power has become fast enough to do anything useful with the science.
However, to fully understand how a neural network (NN) works, [Dimitris Tassopoulos] has stripped the concept down to pretty much the simplest example possible – a 3 input, 1 output network – and run inference on a number of MCUs, including the humble Arduino Uno. Miraculously, the Uno processed the network in an impressively fast prediction time of 114.4 μsec!
Whilst we did not test the code on an MCU, we just happened to have Jupyter Notebook installed so ran the same code on a Raspberry Pi directly from [Dimitris’s] bitbucket repo.
He explains in the project pages that now that the hype about AI has died down a bit that it’s the right time for engineers to get into the nitty-gritty of the theory and start using some of the ‘tools’ such as Keras, which have now matured into something fairly useful.
In part 2 of the project, we get to see the guts of a more complicated NN with 3-inputs, a hidden layer with 32 nodes and 1-output, which runs on an Uno at a much slower speed of 5600 μsec.
This exploration of ML in the embedded world is NOT ‘high level’ research stuff that tends to be inaccessible and hard to understand. We have covered Machine Learning On Tiny Platforms Like Raspberry Pi And Arduino before, but not with such an easy and thoroughly practical example.
