Reading Floppies With An Oscilloscope

There’s a lot of data on magnetic media that will soon be lost forever, as floppies weren’t really made to sit in attics and basements for decades and still work. [Chris Evans] and [Phil Pemberton] needed to read some disks that reportedly contained source code for several BBC Micro games, including Repton 3. They turned to Greaseweazle, an interface board that can dump just about any kind of floppy disk if it is attached to the right drive. The problem is that Greaseweazle couldn’t read the disks due to CRC errors. Time to break out the oscilloscope and read the disk manually, which is what they did.

Greaseweazle provides a nice display of read sectors and shows timing coming from the floppy read head. The disk in question looked good with reasonably clean timing clocks except in the area of one sector. At that point, the clocks degenerated into noise. Looking on the disk, it was easy to see why. The actual media had a small dent in it.

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Project Starline Realizes Asimov’s 3D Vision

Issac Asimov wrote Caves of Steel in 1953. In it, he mentions something called trimensional personification. In an age before WebEx and Zoom, imagining that people would have remote meetings replete with 3D holograms was pretty far-sighted. We don’t know if any Google engineers read the book, but they are trying to create a very similar experience with project Starline.

The system is one of those that seems simple on the face of it, but we are sure the implementation isn’t easy. You sit facing something that looks like a window. The other person shows up in 3D as though they were on the other side of the window. Think prison visitation without the phone handset. The camera is mounted such that you look naturally at the other person through your virtual window.

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Spherical Keyboard Build Leaves Hacker Well-Rounded

Often times we as hackers don’t know what we’re doing, and we sally forth and do it anyway. Here at Hackaday, we think that’s one of the best ways to go about a new project, and the absolute fastest way to learn a whole lot as you go. Just ask [Aaron Rasmussen] regarding this spherical, standing 5×6 dactyl manuform keyboard build, which you can see in a three-part short video series embedded after the break.

[Aaron] gets right down to it in the first video. He had to get creative right away, slicing up the dactyl manuform model to fit on a tiny print bed. However, there’s plenty of room inside the sphere for all that wiring and a pair of Elite-C microcontrollers running QMK. Be sure to turn on the sound to hear the accompanying voice-overs.

The second video answers our burning question: how exactly does one angle grind a slippery sphere without sacrificing sheen or shine? We love the solution, which involves swaddling the thing in duct tape and foam.

You may be wondering how [Aaron] is gonna use any kind of mouse while standing there at the pedestal keyboard. While there is space for a mouse to balance on top, this question is answered in the third video, where [Aaron] learns the truth behind the iconic ThinkPad nubbin and applies this knowledge to build a force-feedback joystick/trackpoint mouse. Awesome answer, [Aaron]!

Not ready to go full-tilt, sci-fi prop ergo? Dip your toe in the DIY waters with a handy macropad.

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Shop Exhaust Fan Salvaged From Broken Microwave

You don’t have to look hard to find a broken microwave. These ubiquitous kitchen appliances are so cheap that getting them repaired doesn’t make economical sense for most consumers, making them a common sight on trash day. But is it worth picking one of them up?

The [DuctTape Mechanic] certainly thinks so. In his latest video, he shows how the exhaust fan from a dead microwave can easily and cheaply be adapted to blow smoke and fumes out of your workshop. While it’s obviously not going to move as much air as some of the massive shop fans we’ve covered over the years, if you’re working in a small space like he is, it’s certainly enough to keep the nasty stuff moving in the right direction. Plus as an added bonus, it’s relatively quiet.

Now as you might expect the exact internal components of microwave ovens vary wildly, so there’s no guarantee your curbside score is going to have the same fan as this one. But the [DuctTape Mechanic] tries to give a relatively high-level overview of how to liberate the fan, interpret the circuit diagram on the label, and wire it up so you can plug it into the wall and control it with a simple switch. Similarly, how you actually mount the fan in your shop is probably going to be different, though we did particularly like how he attached his to the window using a pair of alligator clips cut from a frayed jumper cable.

Got a donor microwave but not in the market for a impromptu shop fan? No worries. We recently saw a dud microwave reborn as a professional looking UV curing chamber that would be the perfect partner for your resin 3D printer. Or perhaps you’d rather turn it into a desktop furnace capable of melting aluminum, copper, or bronze.

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Roku TV Hacked To Run Philips Ambilight Setup

Roku TVs are interesting beasts, which use automatic content recognition on whatever you happen to be watching in order to market online streaming services direct to your loungeroom. [Ammar Askar] realised that this technology could instead be used to feed data to a computer to run a Philips Ambilight setup natively from whatever the TV displays. 

The core of the hack came about because [Ammar’s] TV doesn’t work natively with Philips Ambilight technology. Most off-the-shelf solutions involve feeding sources, like Chromecasts or game consoles, to a HDMI splitter and then to a PC running the Ambilight software, but it gets messy real quick. Instead, [Ammar] realised that the Roku-enabled TV should be more than capable of working with the Ambilight system, given the capability of its inbuilt hardware.

The hack consists of a custom app running on the Roku hardware, which uses the in-built Roku libraries to capture frames of whatever is being displayed on the TV. It then breaks up the screen into sections and averages the color in each area. This data is then passed to a laptop, which displays the relevant colors on its own screen, where the standard Philips Hue Sync app handles the Ambilight duties.

It’s a great hack and [Ammar] doesn’t skimp on the granular fine details of what it took to get this custom code running on the Roku TV. We’d love to see more hacks of this calibre done on smart TVs; after all, there’s plenty of horsepower under the hood in many cases. Alternatively, you could always follow the CIA’s example and turn your Samsung TV into a covert listening device. Video after the break.

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Practical Sensors: The Hall Effect

Measuring a magnetic field can be very easy with some pretty low tech, or it can be very high tech. It just depends on what kind of measurement you need and how much effort you want to expend. The very simplest magnetic sensors are reed switches. These are basically relays with no coil. Instead of a coil, an external magnet gets close enough to make or break the contacts in the reed. You see these a lot in, for example, door alarm sensors.

Then again, there’s no real finesse to a reed. It changes state when it sees enough of a magnetic field and that’s about all. You could use a compass with some sort of detection on the needle to get some more information about the field, but not much more. That was, however, how early magnetometers worked. Today, you have lots of options, including the nearly ubiquitous Hall effect sensor.

You might use a Hall effect to measure the magnetic button on a keyboard key coming down when you press it or the open and closed state of a valve. A lot of Hall effects see service as current monitors. Since a coil generates a magnetic field proportional to the current through it, a magnetic sensor can estimate the current in a coil of wire without any physical contact. Hall effects can also watch a magnet go by in a linear motion system or a rotating system to get an idea of position or speed. For example, check out this brushless motor controller that uses three sensors to understand the motor’s position.


Edwin Hall identified the effect in 1879. The basic idea is simple: an electrical conductor carrying current will exhibit changes due to an external magnetic field nearby. These changes show up as voltage you measure across the conductor. Normally, the voltage across a conductor will be nearly zero, but with a magnetic field, you’ll get a non-zero reading in proportion to the magnetic field strength in a particular plane, as we’ll see shortly.

Hall effect sensors are just one type of modern magnetometer. There are many different kinds including those that use inductive pickup coils that may or may not rotate or a fluxgate, which is a special type of coil. Some use a scale or a spring to measure force against another magnet — sometimes microscopically. You can even detect a magnetic field using optical properties like the Kerr effect or Faraday rotation.

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3D Printing Omni-Balls For Robot Locomotion

Wheels are all well and good for getting around, but they only tend to rotate about a single axis. Omni-wheels exist, but they’re still a little too pedestrian for [James Bruton]. His latest project involved 3D printing custom omni-balls which roll in all directions. (Video, embedded below.)

The omniball concept comes from earlier work by Osaka University, which also produced a treaded tank-like vehicle by the name OmniCrawler as well. The spherical design, fitted with an axle and casters as well, allows rotation in multiple directions, allowing for a platform fitted with such omni-balls to easily rotate and translate in all directions.

[James] set about creating his own version of the design, which relies on grippy TPU filament for grip pads to give the 3D printed hemispheres some much needed grip. There’s also bearings inside to allow for the relative rotation between the hemispheres and the internal castor, necessary to allow the wheels to move smoothly when sitting on either pole of the hemispheres. Skate bearings were then used to assemble three of the omni-balls onto a single platform, which demonstrated the ability of the balls to roll smoothly in all directions.

While it’s just a demonstration of the basic idea for now, we can imagine these balls being used to great effect for a robot platform that needs to navigate in tight spaces on smooth surfaces with ease. The mechanical complexity of the omni-balls probably negates their effective use in dirtier offroad contexts, however.

We’ve seen [James]’s work before too – such as his compliant leg design for walking robots, and his active gyroscope balancer last week. When does [James] sleep?

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