Author: Al Williams

4469 Articles

Test For 3D Printer Runaway

September 1, 2021 by 22 Comments

A few 3D printers have had a deserved reputation for bursting into flames. Most — but apparently not all — printers these days has firmware that will detect common problems that can lead to a fire hazard. If you program your own firmware, you can check to see if you have the protection on, but what if you have a printer of unknown provenance? [Thomas] shows you how to check for a safe printer. Also check out his video, embedded below.

The idea is to fake the kind of failures that will cause a problem. Primarily, you want to have the heaters turned on while the thermistor isn’t reading correctly. If the thermistor is stuck reading low or is reading ambient, then it is possible to just drive the heating element to get hotter and hotter. This won’t always lead to a fire, but it could lead to noxious fumes.

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Linux Fu: User Space File Systems — Now For Windows, Too!

August 31, 2021 by 15 Comments

One of the nice things about the Unix philosophy that Linux inherited is that the filesystem is very modular. That’s good, too, because a typical system might want a choice of filesystems like ext4, reiserfs, btrfs, and even network systems like nfs. Besides that, there are fake file systems like /sys and /dev that help Linux make everything look like a file. The downside is that building a filesystem required changing the kernel or, at least, writing a loadable module. That’s not as hard as it sounds, but it is a little more difficult than writing a normal program. Then came FUSE — file system in user space. This is a single file system module that allows you to create new file systems by writing ordinary code.

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Printing Ceramics Made Easier

August 30, 2021 by 3 Comments

Creating things with ceramics is nothing new — people have done it for centuries. There are ways to 3D print ceramics, too. Well, you typically 3D print the wet ceramic and then fire it in a kiln. However, recent research is proposing a new way to produce 3D printed ceramics. The idea is to print using TPU which is infused with polysilazane, a preceramic polymer. Then the resulting print is fired to create the final ceramic product.

The process relies on a specific type of infill to create small channels inside the print to assist in the update of the polysilazane. The printer was a garden-variety Lulzbot TAZ 6 with ordinary 0.15mm and 0.25mm nozzles.

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Regen Receiver With Few Parts

August 30, 2021 by 22 Comments

We like regenerative receivers. They perform well and they are dead simple to create. Example? [Radio abUse] modified a few existing designs and built a one-transistor receiver. Well, one transistor if you don’t count the dozens that are probably on the audio amplifier IC, but we won’t quibble. You can watch a video about the simple receiver — which looks good on a neatly done universal board — below.

The coil of #22 wire dominates the visual layout, and we imagine winding it might have been the most time-consuming part of the project. The layout would work with a single-sided PCB and would be a great board to produce by hand if you were inclined to develop that skill.

Regenerative receivers work by holding an amplifier just shy of oscillating at a certain frequency. This provides extremely high gain at a particular frequency which allows just a single stage to really pull in signals.

We were a little sad to find out there was a plan to tear the radio down to build something else. But, we suppose, that’s progress. We’d be tempted to make a module out of the audio amplifier and then keep the RF section intact. But, then again, we have a lot of partial projects like that gathering dust on the shelf, so maybe that’s not such a great idea.

While regenerative receivers aren’t the most common architecture today, they still have their place. The inventor, Edwin Armstrong, developed quite a bit of radio tech that we still use today.

Dyson Award Goes To Emergency Medical Device For Treating Stab Wounds

August 29, 2021 by 68 Comments

[Joseph Bentley] must be one of those people who sees opportunity in problems. He had several friends who were victims of knife attacks, so he developed REACT, a device that would allow police or other first responders to quickly help victims of stab wounds. The project won the Dyson award and you can see the video about it, below.

The device has two parts: a medical-grade silicone sleeve and a handheld actuator. The sleeve actually inserts into the stab wound and the actuator pressurizes the sleeve based on the location of the wound. The actuator has a user interface to allow the operator to select the area of the body affected.

We don’t know much about emergency medicine, but apparently, the current method is to apply pressure externally and this doesn’t do much for internal bleeding. The sleeve solves that and [Bentley] thinks the device can save many lives if brought to market. Of course, getting a medical device actually on the market is a long road fraught with regulatory peril. We hope the Dyson award will help [Bentley] get the product in the hands of people who can use it to good purpose.

We are very interested in replacing damaged body parts, but saving people from losing body parts or life is good, too. Sometimes, just calling for help is worthwhile.

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1949 Gyroscope Spins Up Again

August 29, 2021 by 10 Comments

[Curious Marc] has an Apollo-era gyroscope but isn’t quite ready to put it through this paces without some practice. So he borrowed a 1949 vintage Sperry C5 gyro and did some experiments with it using a 3-phase power supply he plans to use on the other gyro.

There is a little bit of troubleshooting and a lot of gorgeous close up shots of these electromechanical marvels. They sure are noisy, though.

[Marc] wanted a gyro testing table that can control the orientation of a gyro under test. He went the auction route to get a pretty expensive piece of gear for a relatively low price but without the expensive software. In a stroke of luck, he managed to score the required software from the vendor who was intrigued by his project. It looked to us like a table like this wouldn’t be that hard to build from scratch, either.

We are interested in what [Marc] will do with his gyros next. It is hard to imagine that gyros have come from this sort of device to a tiny IC inertial measurement unit that can fit in a phone. Imagine packing the Sperry unit on your next walking robot or self-balancing unicycle.

Need a refresher on how gyro’s work? We got that, too. It even covers the modern kind.

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Turning Heat Into Electricity

August 28, 2021 by 7 Comments

You don’t really create energy, you convert it from one form to another. For example, many ways that we generate electricity use heat from burning or nuclear decay to generate steam which turns a generator. Thermocouples generate electricity directly from heat, but generally not very much. Still, some nuclear batteries directly convert heat to electricity, they just aren’t very efficient. Now researchers have developed a way of preparing a material that is better at doing the conversion: tin selenide.

Tin selenide is known to have good performance converting heat into electricity when in its crystal form. However, practical applications are more likely to use polycrystalline forms, which are known to have reduced conversion performance.

The material works well because it is not very thermally conductive and it has a favorable band structure that allows multiple bands to participate in charge transport. However, in polycrystal configurations, the results are not as good due to higher thermal conductivity. Yet crystalline tin selenide is difficult to manufacture and not very robust in real-world use.

The team worked out that the polycrystal material’s thermal properties were due to tin oxide films on the surface. Using a particular method of construction, you can remove the tin oxide and improve performance even better than the crystal version of tin selenide.

Creating this material might be beyond your garage lab, though. You need a fused silica oven that can reach a pretty tight vacuum. Although you might be able to swing it. Otherwise, you might stick with more conventional methods.