Two Stage Refrigerator Is Chill

May 16, 2023 by 13 Comments

Every time we check in with [Hyperspace Pirate] he’s trying to make things cold. Really cold. His recent two-part video shows a propane vapor compression system that can go down to -37° C as well as a two-stage system using homemade ethylene that can get to -83° C. He’s trying to get to -100°, so he’s close, and we have no doubt he’ll get there.

The video explains that using two different refrigerants makes the design more practical. At the low temperatures involved, you have to deal with compressor oil freezing. There is a lot of theory required to design an efficient cooler and a lot of know-how required to make gas-tight connections with all the different materials involved.

Using propane in both stages did provide a little additional cooling. But using ethylene in the second stage didn’t work as expected. There were two issues to work through. Part of it was the average temperature of the system, and also, the homemade ethylene needed purification. The ethylene purification setup was almost as complex as the main system and also reminded us, for some reason, of the movie Darkstar. It didn’t work as well as he wanted, which means we have to wait for part two to see it all actually working.

We’ve seen this same guy make dry ice. He’s also tried to make liquid nitrogen, too.

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Astronaut Tracy Caldwell in the International Space Station. (Credit: NASA)

Making The Case For All-Female Exploration Missions To Mars And Beyond

May 16, 2023 by 118 Comments

A recent study in Nature Scientific Reports by Jonathan P. R. Scott and colleagues makes the case for sending exclusively all-female crews on long-duration missions. The reasoning here is simple: women have significant less body mass, with in the US the 50th percentile for women being 59.2 kg and 81.8 kg for men. This directly translates into a low total energy expenditure (TEE), along with a lower need for everything from food to water to oxygen. On a long-duration mission, this could conceivably save a lot of resources, thus increasing the likelihood of success.

With this in mind, it does raise the question of why female astronauts aren’t more commonly seen throughout Western space history, with Sally Ride being the first US astronaut to fly in 1983. This happened decades after the first female Soviet cosmonaut, when Valentina Tereshkova made history in 1963 on Vostok 6, followed by Svetlana Savitskaya in 1982 and again in 1984, when she became the first woman to perform a spacewalk.

With women becoming an increasingly more common sight in space, it does bear looking at what blocked Western women for so long, despite efforts to change this. It all starts with the unofficial parallel female astronaut selection program of the 1950s.

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DIY Programmable Guitar Pedal Rocks The Studio & Stage

May 16, 2023 by 10 Comments

Ever wondered how to approach making your own digital guitar effects pedal? [Steven Hazel] and a friend have done exactly that, using an Adafruit Feather M4 Express board and a Teensy Audio Adapter board together to create a DIY programmable digital unit that looks ready to drop into an enclosure and get put right to work in the studio or on the stage.

The bulk of the work is done with two parts, and can be prototyped easily on a breadboard.

[Steven] also made a custom PCB to mount everything, including all the right connectors, but the device can be up and running with not much more than the two main parts and a breadboard.

On the inside, the Adafruit Feather M4 Express board works with the audio board over I2S, a standard for sending serial digital audio between chips. Working with the audio itself is done with the Teensy Audio Library, providing a fantastic array of easy-to-use functions for processing and manipulating digital audio streams.

Together, all the right pieces are in place and [Steven] provides the code for a simple tremolo effect as a glimpse of what’s possible with the unit. Interested in going a bit further? [Steven] shares additional details about what’s involved in writing a custom effect from scratch using the Teensy Audio Library.

As mentioned, I2S is where it’s at when it comes to working with digital audio at the chip level, and our own Jenny List can tell you everything you need to know about I2S, a useful protocol that has actually been around since 1982!

The MOS CIA Lives On, In 74HCT

May 16, 2023 by 12 Comments

It’s always pleasing to see a project we covered in its early stages reach maturity, so were very happy to bring you an update on [Daniel Molina]’s 74HCT6526. It’s a long-running effort to produce in 74 logic a faithful replica of the MOS Technologies CIA, the integrated I/O and timer chip found in so many of the 1980s Commodore machines. When we first covered it there was only one PCB, now the project has grown to a stack of three, with the remaining functions intended to fit on two more boards.

It was very common at the time for chips such as the CIA to integrate a set of common 8-bit peripherals onto one piece of silicon, both in general purpose with almost all functions of the original now implemented. hips and in more manufacturer specific parts such as this one. A project like this one is valuable because it provides a dive into the now less-common  world of interfacing directly to a microprocessor data and address line. It’s unlikely that many Commodore 64s will end up with this stack of boards inside them, but it’s not impossible the design may help a few old machines when put on an FPGA.

Meanwhile, remember it’s not the only custom 1980s home computer chip replaced with 74 logic.

A Paste Extruder For Normal Printers

May 15, 2023 by 17 Comments

In the bright sunshine of a warm spring afternoon at Delft Maker Faire, were a row of 3D printers converted with paste extruders. They were the work of [Nedji Yusufova], and though while were being shown printing with biodegradable pastes made from waste materials, we were also interested in their potential to print using edible media.

The extruder follows a path set by similar ones we’ve seen before in that it uses a disposable syringe at its heart, this time in a laser-cut ply enclosure and a lead screw driven by a stepper motor. It’s part of a kit suitable for run-of-the-mill FDM printers that’s available for sale if you have the extra cash, but happily they’ve also made all the files available.

We’ve seen quite a few syringe extruders and at least one food printer, so there’s nothing particularly new about this one. What it does give you is a relatively straightforward build and a ready integration with some mass market printers you might be familiar with. Perhaps the most interesting part of this project isn’t even the extruder itself but the materials, after all having a paste extruder gives you the opportunity to experiment with new recipes. We like it.

Modern CO2 Laser Reviewed

May 15, 2023 by 14 Comments

If you’ve got a laser cutter, it is highly probable that it uses a laser diode. But more expensive machines use a carbon dioxide laser tube along with mirrors. There was a time when these lasers came in two flavors: very expensive and amazing or moderately expensive and cheaply made. However, we are seeing that even the moderately expensive machines are now becoming quite advanced. [Chad] reviews a 55-watt xTool P2. At around $5,000, it is still a little spendy for a home shop, but it does have pretty amazing features. We can only hope some less expensive diode lasers will adopt some of these features.

[Chad’s] video that you can see below attempts to recreate some of the amazing things xTool did on their product introduction live stream. He was able to recreate most, but not all of the results. In some cases, he was also able to do better.

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Wood game piece being carved by a CNC mill with a hacked rotary axis

This $12 CNC Rotary Axis Will Make Your Head Spin

May 15, 2023 by 20 Comments

[legolor] brings us a great, cheap rotary axis to add to your small 3 axis CNC mills. How are you going to generate G-Code for this 4th axis? That’s the great part, and the hack, that [legolor] really just swapped the Y axis for the rotation. To finish the workflow and keep things cheap accessible to all there’s a great trick to “unwrap” your 3D model so your CAM software of choice thinks it’s still using a linear Y axis and keeps your existing workflow largely intact. While this requires an extra step in Blender to do the unwrapping, we love the way this hack changes as little of the rest of your process as possible. The Blender script might be useful for many other purposes too.

Wood game pieces carved from wood by a CNC mill with a hacked rotary axis

The results speak for themselves too! We thought the 3D printed parts were suspect in a CNC setup, but for the small scale of game pieces and milling wood, the setup is stable enough to produce a surprisingly accurate and detailed finish. If you want to try the same approach with something larger or a tougher material, [legolor] has a suggestion of a tailstock setup that’s still under $100 USD. Continue reading “This $12 CNC Rotary Axis Will Make Your Head Spin” →