Author: Zoe Skyforest

3791 Articles

HAWT Wind Turbine Is Mostly 3D Printed

August 7, 2020 by 13 Comments

Wind turbines are a great source of renewable energy, and a great DIY project, too. They can be built with all kinds of materials and the barrier for entry is low for the beginner. [Fab] has built just such a device, taking advantage of modern construction techniques, and dubbed it the WinDIY.

The WinDIY design is mostly 3D printed, with a familiar three-bladed design. The diameter of the rotor is 1.2 m, meaning that braking and regulating the turbine is required for safety in high winds. [Fab] is aiming to achieve this control with a combination of mechanical and electronic braking, as well as variable-pitch blades. The benefit of 3D printing the design is it allows iterations to be made quickly, particularly of parts with complex geometries that would be too time-consuming or expensive to machine otherwise.

[Fab]’s writeup goes into great detail on topics like the design of the pitch control systems and other minutae, which should serve as a great reference for anyone else working on a similar project. If you’re looking for something with more of a sci-fi future vibe, consider attempting a vertical-axis build instead.

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Optimizing GIF Playback For Microcontrollers

August 3, 2020 by 15 Comments

Despite being cooked up by Compuserve back in the late 1980s, GIFs have seen a resurgence on the modern internet, mostly because they’re fun. However, all our small embedded systems are getting color screens these days, and they’d love to join in the party. [Larry Bank] has whipped up a solution for just that reason, letting embedded systems play back short animated GIFs with limited resources.

[Larry] does a great job of explaining how the GIF format works, using LZW compression and variable-length codes. He talks about how the design of the format presents challenges, particularly when working with microcontrollers. Despite this, the final code works well, and is able to work with most animated GIFs of the right dimensions and construction. 24K of RAM is required, and image width is limited to 320 pixels. Images can be loaded from flash, memory, or SD cards, and he notes that best performance is gained with a microcontroller with fast SPI for writing to screens quickly.

It’s a great piece of software that promises to add a lot of charm, or silliness, to microcontroller projects. It also simplifies the use of animations, which can now be designed on computers rather than by using onboard graphics libraries. GIF really is the format that never seems to die; we’ve featured cameras dedicated to the form before. Video after the break.

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Cryptographic LCDs Use The Magic Of XOR

August 3, 2020 by 8 Comments

Digital security is always a moving target, with no one device or system every being truly secure. Whether its cryptographic systems being compromised, software being hacked, or baked-in hardware vulnerabilities, it seems there is always a hole to be found. [Max Justicz] has a taste for such topics, and decided to explore the possibility of creating a secure communications device using a pair of LCDs.

In a traditional communications system, when a message is decrypted and the plaintext is displayed on screen, there’s a possibility that any other software running could capture the screen or memory state, and thus capture the secret data. To get around this, [Max]’s device uses a concept called visual cryptography. Two separate, independent systems with their own LCD each display a particular pattern. It is only when the two displays are combined together with the right filters that the message can be viewed by the user, thanks to the visual XOR effect generated by the polarized nature of LCDs.

The device as shown, working with both transparent OLEDs and traditional LCDs, is merely a proof of concept. [Max] envisions a device wherein each display is independently sourced, such that even if one is compromised, it doesn’t have the full message, and thus can’t compromise the system. [Max] also muses about the problem of side-channel attacks, and other factors to consider when trying to build a truly secure system.

We love a good discussion of cryptography and security around here; [John McMaster]’s talk on crypto ignition keys was a particular hit at Supercon last year. Video after the break.

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Pinephone Gets Thermal Imaging Backpack

August 3, 2020 by 12 Comments

When you buy a mass-market mobile phone, you’re making the decision to trust a long list of companies with your private data. While it’s difficult for any one consumer to fully audit even a single piece of consumer technology, there have been efforts to solve this problem to a degree. The Pinephone is one such example, with a focus on openness and allowing users to have full control over the hardware. [Martijn Braam] is a proud owner of such a device, and took advantage of this attitude to add a thermal imager to the handset.

The build is not a difficult one, thanks to the expansion-friendly nature of the Pinephone hardware. The rear of the phone sports six pogo pins carrying an I2C bus as well as power. [Martin] started by modifying the back cover of the phone with contacts to interface with the pogo pins. With this done, the MLX90640 thermal imager was attached to the case with double-sided tape and wired up to the interface.

While the 32×24 output from the sensor isn’t going to help you build cutting edge heat-seeking missiles, it’s an affordable sensor with good performance for low-end thermal imaging tasks. We’ve featured teardowns of thermal imaging hardware before, too.

Swimming Pool Lap Counter Relies On Ultrasound

August 2, 2020 by 8 Comments

Swimming is a great way to exercise, both for the cardiovascular benefits and the improved muscle tone. However, while he’s a fan, [Peter Quinn] sometimes finds it hard to keep track of how far he’s gone when he gets in the zone. Obviously, the solution is an electronic lap counter, which [Peter] promptly set about creating.

The build is based around an ultrasonic distance sensor, which is triggered when it detects a swimmer approaching the end of the lane. It’s run by an Arduino Nano, which is also set up to announce the accumulated distance with a speech synth library. [Peter] notes there have been some stumbling blocks thus far, necessitating modifications along the way. Water ingress into the ultrasonic sensor has required the installation of a protective shroud, while battery operation has required a module to properly handle the lithium-polymer battery.

While we might hesitate to bring a takeaway container full of wires, circuit boards and an LED display to a public pool for fear of being deemed a bomber, the basic bones of the project are a great way to approach the problem. There’s plenty of scope to implement laptiming too, as we’ve seen in other sporting builds!

Sanitizer Dispenser Does It Hands-Free

July 31, 2020 by 11 Comments

Hand sanitizer is the hot product of 2020, and it seems nobody can get enough. In the same way that touching a dirty tap takes the shine off washing your hands in a public bathroom, one wishes to avoid touching the hand sanitizer bottle entirely. To get around this, [makendo] whipped up a quick solution.

The solution consists of a 3D printed caddy which holds a typical bottle of hand sanitizer. This is affixed to a wall with either screws or double sided tape. A long string is then attached to the dispenser nozzle, and passes down to a foot pedal. By depressing the pedal, it pulls on the string, pulling down the dispenser nozzle and delivering the required sanitizer to the hands.

It’s by no means an advanced hack, but one that can be whipped up in a short time to make sanitizing one’s hands just that little bit more pain-free. If you’re still short on sanitizer, you might want to make your own. If you do, let us know how it goes. Otherwise, consider alternate methods of automating the delivery!

Producing A Prop Gun That Actually Ejects Cases

July 31, 2020 by 34 Comments

With the movie Man of War shooting in Cyprus, there was a problem. They needed prop guns that looked realistic and ejected cases when fired, but that were also allowed under the country’s firearm laws. The task fell on [Paradym’s] shoulders, and he set to work producing a prop capable of doing the job.

With the laws in Cyprus, using anything off-the-shelf like an Airsoft pistol was simply not allowed. Instead, he had to start from scratch, creating a design outwardly similar to the Colt 1911 to suit the era of the film. Using green gas canisters for power, the first focus was on getting a realistic semi-automatic firing cycle happening. With that done, the next goal was to get the cases to eject from the weapon on each shot. To achieve this, a lever was used, actuated by the slide moving back after a shot, pushing the “spent” cartridge out of the port.

[Paradym] goes into great deal, covering the design of the 3D printed parts, the machining of springs, as well as the final assembly of the prop. We’ve seen other prop gun builds before, too. Video after the break.

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