Repairing 14 Tektronix TLA5202 Logic Analyzers

[Matthew D’Asaro] was recently entrusted with an entire classroom fleet of fourteen broken Tektronix TLA5202 logic analyzers — a pile of equipment that once was worth hundreds of thousands of dollars. His task: Fixing them. He fixed them all, and on the way documented a number of common failure points in these old but still great devices.

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An Organ Made from Back-Driven Steppers

[Josh] wrote in to tell us about an experimental instrument he’s been working on for a couple of months. We’re glad he did, because it’s a really cool project. It’s an organ that uses the principle of back-drive—applying torque to the output shaft of a motor—to create sounds.  [Josh] is back-driving four octaves worth of stepper motors with spinning wooden disks, and this generates alternating current. At the right speeds, the resulting sinusoidal waveform falls within the range of human hearing and can be amplified for maximum musical enjoyment.

[Josh] built this organ from the ground up, including the keys which are made from oak and walnut. Each of the forty-nine stepper motors has a corresponding wooden disk. The larger the wooden disk in the stack, the higher the resulting pitch. [Josh] says that if he built it for a full 88 keys, the highest note’s disk would be sixteen feet in diameter.

This stack of disks is driven independently by a separate DC motor, and the speed determines the key it will play in. When [Josh] plays a note, that note’s lever is actuated and its stepper motor makes contact with its disk in the stack. When they meet, the motor is back-driven by the spinning disk. In other words, they work in concert to produce some cool, eerie sounds.

Here’s a somewhat similar sort of build made from lasers and fans, if you consider that both instruments create music from objects that weren’t built to do so. Watch [Josh] play his stepper organ after the break. He has several build videos on his YT channel, and we’ve also embedded the one that covers the motor, power, and electronics part of the build.

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A Windowless Elevator with a 360º Panoramic View

The Amoreiras Tower, in Lisbon, Portugal, recently added a rooftop viewing area that is open to the public. The top of the tower is one of the highest spots in the city, and the viewing area gives an impressive 360º view of the surrounding area. However, the elevator to get to the top left a lot to be desired. It’s an interior elevator, and didn’t itself offer any view.

So, Artica, along with Schindler, were brought in to solve that problem. The solution was to mount displays on the interior of the elevator, in order to simulate a 360º panoramic view of the city outside. The video is synced up with the elevator, so the view changes as the elevator passengers move up and down between floors.

Artica, who was responsible for the concept, design, and electronics installation accomplished this by first building a prototype in their office building. This was a full-size elevator replica with which they could test the design and get it ready for installation. They then partnered with Schindler to actually install the system in the elevator of the Amoreiras Tower, which necessitated almost completely rebuilding the elevator. As you can see in the video, the resulting view and accompanying music (definitely not elevator music) are fantastic, and it was even done in time for the public opening of the rooftop viewing area.

Like us, you may be wondering where the video footage came from. The scene moves in apparent parallax so video was obviously captured with continuous motion and isn’t a scrolling image. This is the work of a camera toting drone.

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Hackaday Prize Entry: A Raspberry Pi Password Manager

Every week there’s new a new website that has been compromised and the passwords of a few hundred thousand accounts have been leaked to a pastebin. To protect yourself you can change your passwords often, not reuse passwords, and use long compilcated strings; all of these techniques are far beyond the capacity for human memory, or even a Post-it note. Thus the age of electronic password keepers began.

Electronic password keepers are simple devices that save your passwords and can recall them over a USB connection. The Raspberry Pi Zero functions perfectly fine as a USB device, leading [gir] to build the Raspi Zero WiFi Enable Hardware Password Manager for the Hackaday Prize.

This USB gadget uses pass, the ‘standard unix password manager’ to store all the passwords. Everything is controlled by a few buttons, a small OLED display, and of course the Raspi’s ability to become a USB HID device. This allows the Pi Zero to type passwords in just like a USB keyboard.

It’s a great project, and since the Pi Zero actually exists now, much to the surprise of its many detractors, the perfect entry for the Hackaday Prize.

Add Robotic Farming to Your Backyard with Farmbot Genesis

Growing your own food is a fun hobby and generally as rewarding as people say it is. However, it does have its quirks and it definitely equires quite the time input. That’s why it was so satisfying to watch Farmbot push a weed underground. Take that!

Farmbot is a project that has been going on for a few years now, it was a semifinalist in the Hackaday Prize 2014, and that development time shows in the project documented on their website. The robot can plant, water, analyze, and weed a garden filled with arbitrarily chosen plant life. It’s low power and low maintenance. On top of that, every single bit is documented on their website. It’s really well done and thorough. They are gearing up to sell kits, but if you want it now; just do it yourself.

The bot itself is exactly what you’d expect if you were to pick out the cheapest most accessible way to build a robot: aluminum extrusions, plate metal, and 3D printer parts make up the frame. The brain is a Raspberry Pi hooked to its regular companion, an Arduino. On top of all this is a fairly comprehensive software stack.

The user can lay out the garden graphically. They can get as macro or micro as they’d like about the routines the robot uses. The robot will happily come to life in intervals and manage a garden. They hope that by selling kits they’ll interest a whole slew of hackers who can contribute back to the problem of small scale robotic farming.

Turntable Turns Waveform Generator

In need of a waveform generator for another project, [David Cook] crammed out the old turntable to modify it for a handy hack: By adding a simple reflectance sensor to the pickup he turned it into a waveform generator that optically plays back arbitrary waveforms from printed paper discs.

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Laser-Cut ArcSin Dress Is Wearable Math

Using sewing simulation, 3D modeling and laser-cutting [Nancy Yi Liang] makes custom dresses that fit like a glove. Her project documentation walks us through all the steps from the first sketch to the final garment.

After sketching the design on paper, the design process moves into the digital domain, where an accurate 3D model of the wearer is required. [Nancy] created hers with Make Human, a free software that creates to-size avatars of humans from tape-measured parameters. Using the professional garment modeling software MarvelousDesigner (which offers a 30 day trial version), she then created the actual layout. The software allows her to design the cutting patterns, and then also drapes the fabric around the human model in a 3D garment simulation to check the fit. The result are the cutting patterns and a 3D model of the garment.

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