Hackaday Links: July 30, 2023

July 30, 2023 by Dan Maloney 14 Comments

A couple of weeks ago, we noted with interest that the space shuttle Endeavour (OV85) would be set up as a full-stack launch configuration display, complete with external fuel tank and solid rocket boosters. We predicted that this would result in some interesting engineering, not least of which will be making the entire 20-story stack safe from seismic activity. Looks like we were right on all counts, with this story about the foundation upon which the display will stand, which has been under construction for quite a while now. The base has six seismic isolators that support the 2.4-m thick slab of reinforced concrete that will serve as a perch for the full stack. The 1,800-ton slab will be able to move a meter or so from its resting position during earthquakes. Or perhaps more accurately, the foundation will allow Los Angeles to move as much as it wants while Endeavour rides it out.

If like us you’re worried that seismic loads are vastly different than the loads the spacecraft was actually designed for, relax — it turns out that the flight loads are far in excess of predicted loads from seismic stress. The plan is to build the booster stacks first — the aft skirts, which will support the entire stack, were just bolted in place — then lift the external tank in place between the boosters, and finally hoist the actual orbiter into place. After the stack is complete, the rest of the building will be built around it. We’re really looking forward to seeing some video on this project.

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Turning A Window Air Conditioning Unit Into Whole-House AC

July 30, 2023 by Maya Posch 110 Comments

Although air conditioning units are generally subdivided into a number of categories, including window, split and whole house/building units, they still work the same, with the compressor, condenser and expansion stages.

Extending the wiring for the AC unit’s controller board (Credit: HowToLou)

In the case of widely available window AC units you can indeed use them as designed in a window, or as [HowToLou] is in the process of demonstrating, as a whole-house AC unit. The main thing to keep an eye out for here is the rated capacity of the window AC unit (in British Thermal Units, square meters/feet). In this case [Lou] used a pretty beefy $600, 24,000 BTU window unit that should be good for about 1200 sqf (~111 m²) .

Most of the modifications are pretty straightforward, with the control board needing to have its wiring extended, as well as the AC unit’s air intake and exhaust on the indoors side. The unit is then placed outside on a stable foundation and inserted into a suitably sized hole in the side of the building, with the controller’s cable running to it from indoors. For the next step, [Lou] intends to connect the air channels on the AC unit to the house’s furnace ducts, to complete the whole-house AC installation.

Compared to a regular whole-house AC unit, this DIY approach has the advantage of anyone being able to just buy and install a window AC unit, whereas whole-house AC tends to require a licensed installer and a lot of additional costs. How well [Lou]’s DIY approach ends up working will hopefully be revealed in a Part 2.

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The British Government Is Coming For Your Privacy

July 30, 2023 by Jenny List 77 Comments

The list of bad legislation relating to the topic of encryption and privacy is long and inglorious. Usually, these legislative stinkers only affect those unfortunate enough to live in the country that passed them. Still, one upcoming law from the British government should have us all concerned. The Online Safety Bill started as the usual think-of-the-children stuff, but as the EFF notes, some of its proposed powers have the potential to undermine encryption worldwide.

At issue is the proposal that services with strong encryption incorporate government-sanctioned backdoors to give the spooks free rein to snoop on communications. We imagine that this will be of significant interest to some of the world’s less savoury regimes, a club we can’t honestly say the current UK government doesn’t seem hell-bent on joining. The Bill has had a tumultuous passage through the Lords, the UK upper house, but PM Rishi Sunak’s administration has proved unbending.

If there’s a silver lining to this legislative train wreck, it’s that many of the global tech companies are likely to pull their products from the UK market rather than comply. We understand that UK lawmakers are partial to encrypted online messaging platforms. Thus, there will be poetic justice in their voting once more for a disastrous bill with the unintended consequence of taking away something they rely on.

Header image: DaniKauf, CC BY-SA 3.0.

Harvesting Mechanical Energy From Falling Rain

July 30, 2023 by Bryan Cockfield 40 Comments

Collecting energy from various small mechanical processes has always been something that’s been technically possible, but never done on a large scale due to issues with cost and scalability. It’s much easier to generate electricity in bulk via traditional methods, whether that’s with fossil fuels or other proven processes like solar panels. That might be about to change, though, as a breakthrough that researchers at Georgia Tech found allows for the direct harvesting of mechanical energy at a rate much higher than previous techniques allowed.

The method takes advantage of the triboelectric effect, which is a process by which electric charge is transferred when two objects strike or slide past one another. While this effect has been known for some time, it has only been through the advancements of modern materials science that it can be put to efficient use at generating energy, creating voltages many thousands of times higher than previous materials allowed. Another barrier they needed to overcome was how to string together lots of small generators like this together. A new method that allows the cells to function semi-independently reduces the coupling capacitance, allowing larger arrays to be built.

The hope is for all of these improvements to be combined into a system which could do things like augment existing solar panels, allowing them to additionally gather energy from falling rain drops. We’d expect that the cost of this technology would need to come down considerably in order to be cost-competitive, and be able to scale from a manufacturing point-of-view before we’d see much of this in the real world, but for now at least the research seems fairly promising. But if you’re looking for something you can theoretically use right now, there are all kinds of other ways to generate energy from fairly mundane daily activities.

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Vacuum Chamber Gets Automation

July 30, 2023 by Bryan Cockfield 18 Comments

[Nick Poole] does a lot of custom work with vacuum tubes — so much so that he builds his own vacuum tubes of various shapes, sizes, and functions right on his own workbench. While the theory of vacuum tubes is pretty straightforward, at least to those of us who haven’t only been exposed to semiconductors, producing them requires some specialized equipment. A simple vacuum won’t get you all the way there, and the complexity of the setup that’s needed certainly calls for some automation.

The vacuum system that [Nick] uses involves three sections separated by high-vacuum valves in order to achieve the pressures required for vacuum tube construction. There’s a rough vacuum section driven by one pump, a high vacuum section driven by a second pump, and a third section called the evac port where the tube is connected. Each second must be prepared properly before the next section can be engaged or disengaged. An Arduino Pro is tasked with all of this, chosen for its large amount of ADC inputs for the instrumentation monitoring the pressures in each section, as well as the digital I/O to control the valves and switches on the system.

The control system is built into a 19-inch equipment rack with custom faceplates which outline the operation of the vacuum system. A set of addressable LEDs provide the status of the various parts of the system, and mechanical keyboard switches are used to control everything, including one which functions as an emergency stop. The automation provided by the Arduino reduces the chances for any mistakes to be caused by human error, allows the human operator to focus on other tasks like forming the glass, and can also react much faster to any potentially damaging situations such as the high-pressure pump being exposed to atmospheric pressure.

As you can probably tell, [Nick] is pretty passionate about this stuff — last year he gave a talk at the Hackaday Supercon that went over all the intricacies of building one’s own vacuum tubes.

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Self-Hosted Chatbot Focuses On Privacy

July 30, 2023 by Bryan Cockfield 6 Comments

Large language models (LLMs) have been all the rage lately, assisting from all kinds of tasks from programming to devising Excel formulas to shortcutting school work. They’re also relatively easy to access for the most part, but as the old saying goes, if something on the Internet is free the real product is you (and your data). Luckily there are ways of hosting LLMs on your own to avoid your personal data getting harvested, as well as taking advantage of open-source solutions, but building these systems takes a little bit of effort. [Stephen] and a team from Mozilla walk us through this process and show us a number of options currently available.

Working from the ground up, the group first decides on hosting, which (unsurprisingly) involves using Mozilla hosting services. The choice of runtime environment was a little bit more challenging. The project was time constrained, so they looked at two options here: Hugging Face and llama.cpp. Eventually deciding to move forward with llama.cpp largely due to its ability to run on more consumer-oriented hardware (especially Apple silicon) and the fact that it doesn’t need a powerful GPU, the next task was to choose the model. Settling on the LLaMa model that Facebook recently open-sourced, this model works well with the runtime environment and is essentially the only one that does.

From there, the team at Mozilla wanted to make sure their chat bot would be able to provide other Mozilla employees with information more readily pertinent to their jobs, so they trained their model with some internal Mozilla data as well as other more generic information. This doesn’t mean the job is done, though, there are a number of other factors that went in to designing this system before it was finally complete. Even then, since they built this in a week it’s not perfect; there are some issues with non-permissive licensing of some of the components and many of the design choices may not have been ideal. It’s impressive what’s out there if you’re hosting your own system, though, and while this might be a little more advanced for a self-hosted project, take a look at some other more beginner-friendly projects you can try if you’re just starting out on the self-hosted path.

A ZX Spectrum with a Microdrive emulator plugged into its expansion port

A Modern Replacement For The ZX Spectrum’s Odd Tape Storage System

July 29, 2023 by Robin Kearey 44 Comments

Unless you were lucky enough to be able to afford a floppy disk drive, you probably used cassette tapes to store programs and data if you used pretty much any home computer in the 1980s. ZX Spectrum users, however, had another option in the form of the Microdrive. This was a rather unusual continuous-loop mini-tape cartridge that could store around 100 kB and load it at lightning speed, all at a much lower price point than a floppy drive. The low price came at the cost of poor durability however, and after four decades it’s becoming harder and harder to find cartridges that work reliably. [Derek Fountain] therefore set out to make a modern Microdrive emulator that stores data on SD cards.

Several projects already exist to replace Microdrives, but they typically also need the ZX Interface 1, a serial/network expansion module that’s becoming equally hard to find. Hence [Derek]’s choice to make his emulator a completely standalone system that directly plugs into the Spectrum’s expansion port.

The system is housed in a 3D-printed enclosure that holds two PCBs. Three Raspberry Pi Picos run the show inside: one to hold the ZX Interface 1’s ROM image and interface with the Spectrum’s bus, another to simulate the Microdrive, and a third to run the user interface and communicate with the SD card. The user can choose between eight tape images stored in .MDR format by using two pushbuttons and a rotary encoder, with a small OLED display showing the machine’s configuration.

While you might think that three dual-core 133 MHz ARM CPUs would run circles around the Spectrum’s Z80, it actually took quite a bit of work to get everyting running properly in real time. The 3.5 MHz bus clock rate gave the second Pico precious little time to fetch the required bytes out of its flash memory. Its RAM was fast enough for that, but too small to hold all eight tape images at the same time. In the end, [Derek] settled on using a separate 8 MB SPI DRAM chip that could easily keep up the data rate, with the Pi just using its GPIO ports to shuttle the data around.

All source code and extensive documentation are available on Derek’s excellent blog post and GitHub page. Be sure to also check out [Jenny]’s detailed review and teardown if you’d like to know more about the weird and wonderful Microdrive system.

Thanks for the tip, [Andrew]! Continue reading “A Modern Replacement For The ZX Spectrum’s Odd Tape Storage System” →