Mysterious Files PH

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.

Modern computers are towers of glass and metal with very few large deviations from one to another. Monitor A will go against B, except you can’t tell them apart unless they’re on. At least, that is, compared to how different the old bulky monitors look compared to the new. [Andrzej Górski] seems to agree with this sentiment with his Oldputer, a blast from the past.

[Andrzej Górski]’s inspiration came from one component, and the main component of the project, an old e-ink display. When life gives you one of the slowest versions of a display, there really isn’t too much else to do other than pair it with slow old computers of the past. From that inspiration, there isn’t entirely a whole lot to do other than throw in an ESP32 and some LEDs for indicator lights. Put all this into a fun case, and you get one pretty desk ornament for whatever information you wanna display.

If you want to replicate the past again, you might want to look for the project GitHub here. If you’re looking for something even older, check out the replica of the MCM/70!

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.

Hackaday Editors Elliot Williams and Tom Nardi start this episode off with a discussion about Philadelphia’s budding hacker conference and the imminent retirement of the EZ80. After considering the parallels between the wide world of aviation headsets and our personal projects, talk moves on to the exciting developments in the world of software-defined radio on the ESP32, a Meshtastic pager from a bygone era, and how all the wild flying machines entered into DARPA’s Lift Challenge ended up losing to a simple helicopter.

You’ll also hear about turning plastic bottles into printer filament, pushing e-ink screens to their limits, and browsing the web on the PSP in 2026. To wrap things up they’ll marvel at all the modern abstraction sitting between software and the memory it’s running on, and revisit some RF concepts that might be particularly useful now that everyone is playing with a new SDR device.

Check out the links if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download in DRM-free MP3.

Episode 391 Show Notes:

News:

• JawnCon 0x3 Kicks Off In Philadelphia This Friday
• Littelfuse Announces Retirement Of The EZ80

Mailbag:

• You don’t have to reinvent the wheel, but sometimes it can be fun. Thanks [Tom Brusehaver] for the headphone suggestions.

Interesting Hacks of the Week:

• ESP-SDR Can Now Transmit
  • The ESP32, An SDR In Itself
  • GitHub – h0m3us3r/eSpDR · GitHub
  • GitHub – jochenhammes/esp32-sdr-trx: A software-defined transceiver from one ESP32-S3 board: rtl_tcp receiver for SDR++ and FM/SSB voice transmitter for 13 cm (experimental) · GitHub
  • GitHub – z1000biker/esp32c3rxtx · GitHub
  • Using An ESP32-C3’s RF Hardware For DVB-S2 Video Transmission
  • GitHub – barisdinc/ESP32-DATV-SA: Stand-alone fork of SP8ESA/ESP32-DATV: ESP32-C3 DVB-S2 beacon/transmitter without a PC · GitHub
• Pager Converted To Meshtastic Node
• Mars Pathfinder: What Really Happened?
  • The First Bug On Mars
• DARPA Lift Challenge Won By Helicopter
• 2026 Retrocomputing Challenge: USBSID-Pico Has Two SIDs, Many Inputs
• Counting The PET Bottles Needed To Make 1 Kg Of Printer Filament

Quick Hacks:

• Elliot’s Picks:
  • AI Controls IPhone Via ESP32
  • Slim Type For Small Screens, With PixelFonts
  • Rendering 3D Prints From G-Code
• Tom’s Picks:
  • A Modern Browser For The PlayStation Portable
  • Tiny E-Paper Display Delivers 30 FPS Of Game Boy Fun
  • Single Button, Handheld Gaming Console

Can’t-Miss Articles:

• Your Computer Memory Is A Lie
• So You Want To Make Your SDR Work On Other Frequencies

These days, it’s common to give even very young children a mobile device loaded up with educational software that aims to improve everything from basic motor skills to reading and arithmetic. But even the cheapest phone or tablet isn’t the kind of thing most parents would like to see get destroyed, and there’s always a concern about giving children a device that’s capable of connecting to the Internet.

Which is where Braino! from [Ankush Pandit] comes in. This suite of applications can be easily flashed to a common Cheap Yellow Display to turn it into a legitimate educational tool. Combined with a 3D printed case, the total cost of the build is low enough that you don’t have to feel bad about handing it off to even the roughest of youngsters.

[Ankush] makes it clear that this project isn’t trying to sell you anything. You’re responsible for picking up a compatible CYD and installing Braino via the web flashing application. The software is released under the GPLv3 license, and it contains no ads, user accounts, or cloud connectivity. We know not everyone is thrilled with how much time young kids spend staring at screens these days, but opinions on modern parenting aside, it’s hard to find fault with the way things have been implemented here.

When the parent sets up Braino they can pick which of the 40 games can be accessed, allowing the experience to be tailored to the individual child’s age and ability. Should you decide to enable Bluetooth, some of the games even support wireless multiplayer between devices. We also like the beacon function which lets

The commonality of the Cheap Yellow Display is one of its best features, and Braino does an excellent job of showing why that’s so important. Trying to develop a project like this without a standardized platform of some type would be a non-starter, but when anyone can get a CYD sent to their house from Amazon and flash it right from the browser, it’s makes the whole thing far more accessible.

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.