A photo of the various parts for this MSLA 3D printer

Build A 2K Resolution MSLA 3D Resin Printer For Cheap

January 7, 2026 by 10 Comments

Have an old Android device collecting dust somewhere that you’d like to put to better use? [Electronoobs] shows us how to make a Masked Stereolithography Apparatus (MSLA) printer for cheap using screens salvaged from old Android phones or tablets.

[Electronoobs] wanted to revisit his earlier printer with all the benefits of hindsight, and this is the result. The tricky bit, which is covered in depth in the video below the break, is slicing up the model into graphics for each layer, so that these layers can be rendered by the LCD for each layer during the print.

The next tricky bit, once your layer graphics are in hand, is getting them to the device. This build does that by installing a custom Android app which connects to a web app hosted on the ESP32 microcontroller controlling the print, and the app has a backchannel via a USB OTG adapter installed in the device. [Electronoobs] notes that there are different and potentially better ways by which this full-duplex communication can be achieved, but he is happy to have something that works.

If you’re interested in resin printer tech, be sure to check out Continuous Printing On LCD Resin Printer: No More Wasted Time On Peeling? Is It Possible? and Resin Printer Temperature Mods And Continuous IPA Filtration.

The Rise And Fall Of The In-Car Fax Machines

January 7, 2026 by 31 Comments

Once upon a time, a car phone was a great way to signal to the world that you were better than everybody else. It was a clear sign that you had money to burn, and implied that other people might actually consider it valuable to talk to you from time to time.

There was, however, a way to look even more important than the boastful car phone user. You just had to rock up to the parking lot with your very own in-car fax machine.

Continue reading “The Rise And Fall Of The In-Car Fax Machines” →

An RP2040 Powered ADS-B Receiver

January 7, 2026 by 31 Comments

If you’ve ever heard the sound of an aircraft passing overhead and looked at an online plane tracker to try and figure out what it was, then you’ve interacted with ADS-B. It’s a protocol designed to enable easier aircraft monitoring, and it just so happens you can decode it yourself with the right hardware and software — which is how [John McNelly] came to develop ADSBee, an open source ADS-B receiver based around an RP2040.

ADS-B uses on–off keying (OOK) at 1 Mbps, and operates at 1090 MHz. This might seem like a rather difficult protocol to decode on a microcontroller, but the RP2040’s PIO is up to the task. All it takes is a bit of optimization, and a some basic RF components to amplify and digitize the signals.

However, not all aircraft utilize the 1090 MHz ADS-B implementation, and instead use a related protocol called UAT. Operating at 978 MHz, a second receiver is needed for decoding UAT traffic data, which is where the CC1312 comes into play. ADSBee may even be the first open source implementation of a UAT decoder!

What’s quite impressive is the various form factors the module is available in. Ranging from small solder-down modules to weatherproof outdoor base stations, nearly every potential need for an ADS-B receiver is covered. With POE or ESP32 S3 options available, there is no shortage of networking options either!

ADSBees have been placed in numerous locations, ranging from base stations to drones. One user even built out a tiny flight display cluster complete with traffic indicators into an FPV drone.

This isn’t the first time we have seen ADS-B receivers used by drone enthusiasts, but this is certainly the most feature rich and complete receiver we have come across.

Repairing A Self-Destructing SRS DG535 Digital Delay Generator

January 7, 2026 by No comments

There’s a lot of laboratory equipment out there that the casual hobbyist will never need to use, but that doesn’t mean you wouldn’t snap it up if the price is right. That’s what happened when [Tom Verbeure] saw a 1980s digital delay generator at a flea market for $40. Not only is it an excellent way to learn something about these devices, but it also provides a fascinating opportunity to troubleshoot and hopefully fix it. Such was also the case with this Stanford Research Systems (SRS) DG535 that turned out to be not only broken, but even features an apparently previously triggered self-destruct feature.

These devices are pretty basic, with this specimen incorporating a Z80 MPU in addition to digital and analog components to provide a programmable delay with 12.5 nanosecond resolution on its output channels after the input trigger is sensed. For that reason it was little surprise that the problem with the device was with its supply rails, of which a few were dead or out of spec, along with a burned-out trace.

Where the self-destruct feature comes into play is with the use of current boosting resistors around its linear regulators. Although these provide a current boost over what the regulator can provide, their disadvantages include a tendency towards destruction whenever the load on the supply rail decreases. This could for example occur when you’re debugging an issue and leave some of the PCBs disconnected.

Unsurprisingly, this issue caused the same charred trace to reignite during [Tom]’s first repair attempt, but after working up the courage over the subsequent 18 months the second repair attempt went much better, also helped by the presence of the mostly correct original board schematics.

Ultimately the fixes were relatively modest, involving replacing a discrete diode bridge with an integrated one, fixing the -9 V rail with a bodge wire, and replacing the LCD with its busted AC-powered backlight with a modern one with a LED backlight. Fortunately running the 5 V rail at 7 V for a while seemed to have caused no readily observable damage, nor did flipping connectors because of SRS’ inconsistent ‘standards’ for its connector orientations.

Sadly, when [Tom] emailed SRS to inquire about obtaining an updated schematic for this unit — which is currently still being sold new for $4,495 — he merely got told to send his unit in for repair.

Ken Shirriff working on the Commodore PET

This 8-Bit Commodore PET Was Hard To Fix

January 6, 2026 by 10 Comments

Over on [Ken Shirriff]’s blog is a tricky Commodore PET repair: tracking down 6 1/2 bad chips. WARNING: contains 8-bit assembly code.

The Trinity of 1977 which started the personal computer revolution were the Apple II, the Commodore PET, and the TRS-80. In this project it’s a failing Commodore PET which is being restored.

Continue reading “This 8-Bit Commodore PET Was Hard To Fix” →

Faraday Effects Emerging From The Optical Magnetic Field

January 6, 2026 by 14 Comments

As an electromagnetic radiation phenomenon, it’s perhaps not so surprising that light is affected by a magnetic field. This Faraday effect (FE) has been used since its discovery by [Michael Faraday] in 1845 for a wide range of applications, allowing for the manipulation of light’s polarization, something which is very useful in the field of optics, for remote sensing and spintronics. Despite this being such a well-known property of EM radiation a recent study claims to have made a new discovery here, with what they claim is about the ‘optical magnetic field’.

Their central claim is that it is not just the electrical component that contributes to the FE, but also the magnetic one, due to Zeeman energy that expresses itself from the magnetic component as a form of inverse FE. Based on their experimental findings they estimate that it contributes to the final measured FE by about 17% at a wavelength of 800 nm.

While definitely a very niche physics paper, and with no immediate implications, if independently confirmed it could deepen our understanding of the Faraday effect, and how to use it in future technologies.

The Many Questions And Challenges With DIY Hydroelectric Generators

January 6, 2026 by 35 Comments

The concept of building your own hydroelectric generator seems simple at face value: use gravity to impart as much force as possible onto a turbine, which spins a generator, thus generating electricity. If you’re like the bloke over at [FarmCraft101] trying to DIY this with your farm pond and a lot of PVC pipes, you may have some significantly more in-depth questions, especially pertaining to what kind of generator to use. This and other questions, some of which were raised after the previous video in which the first prototype generator was assembled, are answered in this follow-up video.

When you DIY such a hydroelectric system, you have a number of options when it comes to just the turbine design alone, with the Kaplan-style turbine being one of the most straightforward ones – especially if you use a fixed pitch instead of adjustable – but you can go pretty far in the weeds with alternatives. As for the sharp drop-off after the turbine in the used design, the technical term is a draft tube, which is actually more efficient in this kind of low head, high flow hydroelectric dam situation.

After getting his money back for the unusable ‘3 kW’ generator, there were three options left: try an EBay special, get a purpose-built one from a US company, or rewind an alternator stator for higher voltage output than the standard 12/24V. Ultimately option four was chosen, as in ‘all of the above’, so that comparison is coming up  in a future video.

Continue reading “The Many Questions And Challenges With DIY Hydroelectric Generators” →