TechyMagThings

When most radio enthusiasts start trying to pick up signals from satellites, they might put together a quick-and-dirty Yagi antenna and try to catch a repeater as is passes overhead, or they might grab a small unused dish from a satellite TV service and point it up at a weather satellite by hand to try to decode some of the data coming down. But [Cranktown City] had a different approach. He found an eight-foot dish online and built a massive articulating base station out of it as his first exploration into the world of satellites.

The first problem that needs to be solved with a dish of this size is its mounting location. This installation uses a large post and concrete foundation with a custom-fabricated metal base at the bottom. The metal base houses all of the electronics not just for receiving signals from the dish, but also for orienting it properly. That includes a large metal gear driven by a wheelchair motor to control its azimuth and a linear actuator to take care of its elevation. Getting the large dish onto the frame was its own ordeal, complicated by the fact that it’s not uniform in its shape and has to be mounted in a specific orientation.

With everything assembled, the circularly-polarized antenna installed, and the computers up and running, the dish is able to track satellites across the sky and download data from things like GOES weather satellites. [Cranktown City] also built in a system that detects wind and points the dish vertically when it goes above a certain speed. This level of effort is impressive, and absolutely not required to listen in on plenty of sattelite activity out in the sky, but this installation will certainly give [Cranktown City] a lot of mileage and possibly even work for some radio astronomy.

One could make a joke about how an astronaut walking on the lunar surface is rather akin to a cat walking on the carpet in the living room, but out in space the resulting triboelectric discharge can do a lot more damage than just some stinging fingers and a bemused looking cat.

The problem that NASA and other space agencies are dealing with is that the charge that builds up on a lunar-walking astronaut is very hard to equalize with something like a lunar lander. For this reason they have now set up the Lunar Grounding Challenge to consult the public whilst dangling $150,000 of rewards in front of anyone ready to pounce with a good idea.

Here on Earth we got many ways in which we can get rid of such an unwanted charge, with dry winter weather demonstrating quite effectively why humidity is a crucial factor here. With no real atmosphere on the Moon, each astronaut thus becomes a walking capacitor, which is worsened when said astronaut ventures outside of the sunlit areas and then returns to the slightly positively charged lander.

The challenge here is thus to equalize the astronaut and lander, with a design specification of a -100 kV or higher astronaut and about 100 V lander. A resulting current should not exceed 1 mA, ideally less than 0.2 mA to remain below human perception levels. If an arc exists it should not contact the suit or astronaut.

Of course, the most low-tech solution would be to use a resistor to limit the current, but at those voltage ranges it would take an awful long time to bleed off, in an environment that’s basically a perfect insulator as space will never be cold. It definitely seems like a fun challenge to sink one’s fangs into.

Although solar panels may seem like a kind of magic, they’re really quite simple devices, in their silicon form featuring nothing but the p-type silicon wafer and an n-type layer doped with e.g. phosphorus. Because of this simplicity it’s quite possible to make your own solar cells at home using only a few basic, off-the-shelf ingredients and a kiln, which in this recent video by [Dr. Semiconductor] uses a microwave kiln and thus justifies the video’s title.

Even the silicon wafer that you start with can be easily purchased online, though you have to be careful that it’s a bare wafer, without existing etchings on it. On this you need to get a phosphorus-rich layer, which is done by creating a delicious mixture of 1 mL of tetraethyl orthosilicate (TEOS), 0.3 mL of 85 wt% phosphoric acid, 5 mL of ethanol and 0.25 mL of distilled water. After low heat boiling this for 30 minutes, it is spincoated onto the cut square of silicon wafer using a spinning platform, like a PC fan.

Next, you shove the coated silicon into the kiln and put it into the microwave to bake at a fairly low power level for half an hour. In the video it took less than 50% power of the microwave to not melt the silicon, so remember that those microwave kilns get pretty hot.

With the delightful smells of freshly baked silicon now teasing your nostrils, you can then take out the doped silicon to sand or etch off the thin layer of glass that’s formed around the new PV cell. On the clear spots you can now put a gallium-indium contact on the p-type Si side and a wad of indium on the newly doped Si-P side, which are now your contacts for the PV cell.

The full recipe along with many of the issues discussed in the video can also be found on the blog article, though the video conclusion notes that many improvements are still possible. The created PV cell in the video reaches an efficiency of about 5%, but this could be improved through changes like the use of a clean-room, adding an anti-reflection coating and improving the contact with the cell.

Bicycles are the ultimate form of transportation freedom. They’re easy to repair, parts are cheap, and they will travel almost anywhere for free, as long as the rider has enough calories. Their only real downside is dealing with car-dependent societies, but once a year there’s a place in the American desert that eschews all of this and [Attoparsec] decided to take this custom cargo bike modified into an RV out to Burning Man, a place and time that would be perfect for a build like this.

The build started out as a cargo bike, but not many of them have cargo areas long enough to support a sleeping human. To increase this storage capacity, the bed was extended towards the rear. Without moving the axle further back, though, this created a problem with tail-heaviness so two trailer jacks with wheels were added to the back to keep it from occasionally tipping up too far. The sleeping enclosure was built with rigid foam insulation and taped together, in a modified style common to the Burning Man event which helps keep out sun and playa dust. The bicycle recived one last upgrade to the chain to support the extra weight, and a solar-powered refrigerator, and then it was off to the desert.

The bike RV worked well in the end, and even handled a rain storm without the roof leaking. There were some problems with the customized drive train which were solved in the short term by pounding on one of the wheels occasionally with a hammer. [Attoparsec] left the event early for other reasons, though, and might not be back for a while. But vehicles like these are gaining in popularity, presuming there are safe places to ride them. [Paul Elkins] is often making ones like this gas-powered bicycle and trailer camper.

Meshtastic has gained a lot of popularity over the last few years thanks to its low barrier of entry. No licenses are needed and the hardware is dirt cheap, at least when compared to a lot of ham radio gear. But while that physical barrier is low, there is a bit of a learning curve. Part of that comes from the fact that there are a lot of channels and modes that people could be communicating on, and unless the user knows that information up front it can be hard to find where the conversations are happening. [cemaxecuter] noticed this problem and built a Meshtastic sniffer into his radio-forward Linux distribution, DragonOS.

The sniffing software is built in C and comes as a complete standalone binary and does not rely on GNU Radio. With DragonOS up and running and the software loaded, it can look at the entire bandwidth that Meshtastic operates on and detect any traffic and decode it (as long as the key is known). [cemaxecuter] is using a HackRF as a software-defined radio for this project, which he notes doesn’t quite have enough bandwidth to cover every Meshtastic operating frequency, but it can get most of them. After firing up his own node, the software quickly detects it and shows its details in the terminal.

Software like this opens up a lot of opportunities for things that would be tedious, difficult, or impossible to do with with a standard Meshtastic node. Besides finding places where conversations are happening more easily, [cemaxecuter] also suggests that it could be used for wardriving and for locating or finding other networks much more easily. For those who still haven’t tried it out, take a look at this 2023 treatise on the protocol and hardware and then dive right in.

If you need a micro-manipulator, you probably already have a good idea of what it does. For example, you might be moving a probe over an IC die or wafer. You might be looking at something through a microscope. The key is moving something in very small, precise increments along three axes. An open-source design for a micro-manipulator has seen significant improvements lately. You can see several videos about the device below.

The device uses stepper motors, parallel kinematics, and miniature ball joints to achieve precise motion. The recent version 4.0 update fixes a few problems. According to the GitHub page:

• Self-collision during homing fixed.
• Connection of the ball joint block with screws only was not well constrained and could be rotated a bit.
• No reliable way to ensure consistent linkage rod length
• Unnecessary ball joint friction
• Accurate ball position heavily dependent on print quality and corner rounding
• Rubber bands could not be changed or removed once glued in.

We’ve covered earlier versions of this device, and we were watching the improvements to the ball joints. Since then, the project has updated much of its mechanical design and documentation, and it has also changed the API that drives it. It can even use tools in g-code now to support things like fine control over laser engraving.

If you prefer something old-school manual, consider a 3D-printed one.

If there’s one thing everyone hated about Windows 98, was the lack of USB4.0 support. We remember vividly the cries of anguish at the launch party when we found out that 21 years in the future, the operating system wouldn’t support the then-undreamt of speeds of the thunderbolt-based fastest USB protocol. After two decades of living with this crushing disappointment, [Yeo Kheng Meng] has delivered the goods: the most modern of USB interfaces on some very much not modern versions of windows.

This builds on [Yeo Kheng Meng]’s work on xHCI drivers for USB2.0 support, which we covered at the time. Like that hack, this one applies to Windows 98 through 7, and has a similar level of LLM-wrangling involved. There are actually a few parts to it– one is a USB3.0 driver, which replaces the old xHCI98 driver and is available on GitHub. On Windows98, USB3.0 speed caps out around 200 MB/s, likely restricted by Windows98’s maximum request limit of 64kB on USB transfers. Even with the faster bus in action, it can only gobble those tiny blocks of data so fast.

There’s also experimental USB4.0/Thunderbolt support, as stated above. While not as stable as the USB3.0 portion, we’re kind of impressed it runs at all. Thunderbolt is more than just a faster data bus, after all– you have to support multiple protocols. To handle all that you can install xhcicm.sys and have the surreal experience of accessing an docked NVMe drive from the last century’s best Windows via his Stor98 driver. That’s based largely on [SweetLow]’s NVMe9x project, which he forked but is going to be bundled into the main repo.

What might be more helpful to the community than these drivers is [Yeo Kheng Meng]’s fork of QEMU11 that emulates USB4/Thunderbolt hosts and devices. Having a working emulator seems like it would be a huge boon for this sort of semi-automated development. That’s available in its own repo.

Aside from the already-linked USB2.0 drivers, [Yao Kheng Meng] has an impressive retro-computing record, that includes Swift on the Apple II and turning DOS into llama.c habitat. It should be noted that that llama.c’s TinyStories is not the LLM that assisted with this project.

Thanks to [Yeo Kheng Meng] for the tip!