TechyMagThings

Technically all that you need in order to make a drone fly is a single motor and single propeller, but realistically it becomes basically impossible to fly it at that point. In the case of helicopters you therefore need a second rotor somewhere to provide counterbalance to the first and to be able to steer.

There are of course a number of ways to make a drone fly with a single helicopter, but the compromise usually is to use very large propellers, as well as other mechanisms that make for a very large drone. This wasn’t good enough for [Joshua Bird] who wanted to have a very small, single propeller drone.

Key to making it work is not only a very high RPM, but also a hinged propeller hub that manipulates the  angle of the blades in such a way that both pitch and roll can be controlled if you react quickly enough. This turned out to be impossible using standard motor ESCs that do not directly measure the motor’s speed and position but rely on back EMF.

In the final prototype of the drone such details had to be measured directly, with super-fast adjustments to the motor’s speed only possible with custom controller code and a lot of trial and error. Even then the drone would often lose track of its position and crash once more. The solution there was to add an infrared beacon in the room and a sensor on the drone, to give it a fixed reference point.

You can find the project files so far on the GitHub project page, with upcoming changes to the drone design involving improvements like adding a scanner to the drone so that it can autonomously use features in its environment as fixed reference points. That way it might conceivably be able to fly outside as well, which would be quite exciting to see.

On the face of it, making an event badge should be an easy process. After all, most of us can hand-assemble a microcontroller, some buttons, a battery, and a screen. But anyone who has been involved in producing one will tell you, the difference between producing one or two, and making sure hundreds or even thousands appear on day one of the event fully working is enormous. [Nicholas Ficara] produced 1750 of his first badge for Canada’s Hack The North hackathon, and he’s shared the full story.

We’ve been involved with the gestation of more than one badge here at Hackaday, so we recognise some of his learning moments only too well. He approached it with a well-planned series of prototype and release candidate steps to catch the problems, which came in handy as there certainly were a few. Wrong footprints, misplaced components, power supply issues, and rotated parts were fixed, and eventually they were delivered in time. It’s good to see that they were well received and well used at the event.

If you’re thinking of doing a badge we can certainly recommend that you give this a read. A few years ago we wrote up the story of another badge whose creators put in some hard work to save it from a more serious part error.

[Bob the Science Guy] remembers how to use a slide rule. Even after all these years, it is pretty easy to remember how to multiply and divide. If you can’t remember, you can usually work it out, as long as you understand how slide rules work. But what about sine, cosine, and quadratics? [Bob’s] been making videos about topics like this, and if you’ve wanted to put your slide rule collection to practical use, you’ll enjoy these videos. You can see one below.

The trick to the slide rule is that it is deceptively simple. You are in effect adding logarithms and then taking an antilog. The issue is that you still have to have some intuition about the scale of the answer since 2×3 works out the same as 2×3000 or 200×300.

But it is even trickier than that. Adding and subtracting is not easy on the slide rule. [Bob] shows how to use your math skills to convert problems that might have been addition problems into trig problems. So while it might seem more complicated to use trig, it may help work the problem on the slide rule.

We like slide rules. If you don’t have one, try this one in your browser (hint: go full screen and show both sides).

We aren’t sure what [Lazy_Duck] is doing with video games, but it must require a lot of controllers. Dismayed at the cost and complexity of commercial gamepads, they started soldering and 3D printing to get a cheaper basic controller.

The emphasis is on throwing things together, so there’s no dedicated PCB. Just a protoboard with an RP2040-Zero, a joystick, a few buttons, and a microswitch. A 3D-printed case rounds out the project.

On the printing side, the device uses heat-set threaded inserts, which should make for a very sturdy build. For software, the GP2040-CE firmware handles everything, acting like a controller and managing configuration via a web page.

Even if you don’t want a cheap gamepad, you could apply the principles and software used here to create any kind of gamepad you want. The firmware makes good use of the dual-core RP2040. It also offers a lot you could add to your version of the cheap controller, like OLED displays, RGB LEDs, and more.

Of course, you could also get fancy with the 3D printing side, too. For example, a resin printer makes nice button caps.

In a world where wireless earbuds are increasingly seen as devices that you toss into the e-waste bin as soon as they stop working, it’s heartening to see companies take the opposite approach with their designs. In a recent teardown of the new Fairbuds 2 by [iFixit] we get a blow-by-blow report of disassembling one of these devices, getting to its rechargeable LIR1054 coin cell, as well as the very accessible PCB should you have to replace a shorted capacitor or similar issue.

Much like with the first version, the 3.6 V lithium-ion coin cell can be extracted simply by pulling on the battery door, which leverages it out of the enclosure. Despite this easy access method and no glue these earbuds are still IP54 rated, so they’re safe to wear when you’re dashing for shelter in a sudden downpour.

To get further into the device, you have to overcome the plastic clips that hold the enclosure together, along with what appears to be a few dabs of glue. Inside it you find the PCB containing the guts, including the Airoha AB1577S, Cortex-M4F-based IC that provides the Bluetooth Low Energy capabilities as well as enabling the touch control and other features.

Below the PCB is the coin cell holder, followed by the only part that saw real glue usage, namely the driver section. Presumably this is the compromise to keep things like sweat out of the device. Even so, after disassembly [iFixit] managed to reassemble the device and the earbud remained in working condition.

The case for the earbuds is even easier to disassemble, using just some bolts to unfasten. The USB-C port is soldered to the PCB which [iFixit] dinged them on, but still gave it a 10/10 on their repairability score.

Compared to Apple’s AirPods this is obviously a whole different world, although recently [iFixit] was somewhat pleased with the most recent AirPods generation being slightly more repairable, with non-destructive entry for a battery swap at least somewhat feasible.

Determining the shape of an object which can change dynamically is a bit of a challenge, one that especially vexes those who are really into Virtual Reality. Sensing the orientation of various limbs and appendages usually requires external sensors like cameras, or limit the focus to specific details like just the hands and fingers of the player. A more comprehensive and potentially flexible approach might be possible using optical waveguides, as demonstrated by [Qifan Yu] et al. in a recent article in Advanced Intelligent Systems.

Waveguides are structures that guide electromagnetic waves, with optical waveguides such as used here targeting EM radiation in the optical band. This can even allow for the use of cheap and plentiful optical fiber, though here custom elastomeric waveguides are manufactured. These are laid out onto the sheet in a double-sided, overlapping zig-zag pattern, which allows for easy reconstruction of the shape of said sheet based on how the wave propagation through the waveguide changes.

By characterizing the behavior of the signals through the waveguide, its shape and thus that of the sheet can be reconstructed. This was then demonstrated to be accurate by wrapping the sheet around a volunteer’s arm, elow and hand, detecting the flexing and movement of individual joints.

Although fairly bulky in the demonstrated configuration and with an unoptimized algorithm, it’s conceivably something that can be miniaturized to the point where it can be woven into regular fabric. This could make for sensor sheets that could track the configuration of everything from robots to human bodies for something like VR purposes.

In the 8-bit home computer boom of the early 1980s, Sir Clive Sinclair’s machines were always among the cheapest on the market, often packing a surprising level of sophistication in their limited hardware. If there was one component that was key to their success it was the Ferranti ULA, or Uncommitted Logic Array, a clever way to make an ASIC from a chip containing a library of logic parts ready made. The Sinclair ULAs have been reverse engineered, but their full details have remained a mystery. Until now it seems, because here’s [Happy Little Diodes] with a treasure trove of original Ferranti design documents covering all the Sinclair parts.

The documents were picked up on eBay, and contain folders with printouts, engineering drawings, and hand written design notes. They cover the full range of Sinclair products of the era, including the ZX81 and Spectrum, the ZX printer, the Microdrive, the Spectrum Interface 1, and even the curious little flat screen TV. Oddly the IP is now held by the satellite broadcaster Sky as the holder of Amstrad’s portfolio, but fortunately Sky have recognised their historical importance and allowed their sharing with minimal changes. They’re all catalogued with download links in a Google spreadsheet, so dig in and see what you can find. Of particular interest are the ULAs that haven’t been reverse engineered yet, and the subtle differences between different versions of the same ULA as the engineers tried to fix bugs. The video is below the break.

If you’re curious about the ULA and Ferranti, we linked to a period film about it.