Train Speed Signaling Adapted For Car

September 11, 2024 by Bryan Cockfield 33 Comments

One major flaw of designing societies around cars is the sheer amount of signage that drivers are expected to recognize, read, and react to. It’s a highly complex system that requires constant vigilance to a relatively boring task with high stakes, which is not something humans are particularly well adapted for. Modern GPS equipment can solve a few of these attention problems, with some able to at least show the current speed limit and perhaps an ongoing information feed of the current driving conditions., Trains, on the other hand, solved a lot of these problems long ago. [Philo] and [Tris], two train aficionados, were recently able to get an old speed indicator from a train and get it working in a similar way in their own car.

The speed indicator itself came from a train on the Red Line of the T, Boston’s subway system run by the Massachusetts Bay Transportation Authority (MBTA). Trains have a few unique ways of making sure they go the correct speed for whatever track they’re on as well as avoid colliding with other trains, and this speed indicator is part of that system. [Philo] and [Tris] found out through some reverse engineering that most of the parts were off-the-shelf components, and were able to repair a few things as well as eventually power everything up. With the help of an Arduino, an I/O expander, and some transistors to handle the 28V requirement for the speed indicator, the pair set off in their car to do some real-world testing.

This did take a few tries to get right, as there were some issues with the power supply as well as some bugs to work out in order to interface with the vehicle’s OBD-II port. They also tried to use GPS for approximating speed as well, and after a few runs around Boston they were successful in getting this speed indicator working as a speedometer for their car. It’s an impressive bit of reverse engineering as well as interfacing newer technology with old. For some other bits of train technology reproduced in the modern world you might also want to look at this recreation of a train whistle.

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Rescuing High-Res Displays From Older Macs

September 10, 2024 by Bryan Cockfield 26 Comments

When Apple started rolling out its Retina displays, it multiplied the amount of pixels compared to their standard, non-Retina displays by four. This increased pixel density while keeping the standard screen size — idea for those needing a lot of detail for their work. But, as is common with Apple, using these displays outside of the Apple ecosystem can be quite a challenge. Retina displays have been around for about a decade now, though, with some third-party hardware able to break them free of their cage. This post details how [Kevin] liberated the 5K display from a 2017 iMac for more general use with support for USB-C.

The first step was to find a used iMac for the right price, and then sell off most of its parts to recoup most of the initial cost. That brought the cost of the panel itself to about $250. The key to getting the display working without all of the Apple hardware is the R1811 driver board, which can be had for around $300. A new 156 watt power supply was added to the mix, and [Kevin] also put in a few extras like a USB cable extension and a latching push-button which kills the display’s power. Additionally, he attempted to get the original iMac speakers working with this setup too, but none of his attempts resulted in anything close to quality sound so he’s mostly abandoned that extra feature for now.

With that all buttoned up, he has a 27″ 5K display with USB-C input for around $650 which is quite a deal. The MacRumors thread that [Kevin] added his project to currently has around 1,700 posts about similar builds too, so it can be a wealth of information for all kinds of models. As Apple drops support for their older machines, these displays will become more and more common and projects like these can keep a lot of e-waste out of the landfill while also providing decent hardware at a bargain price. Don’t just look for iMacs and MacBooks though; there’s a similar process to use various iPad displays for other things as well.

Comparing AliExpress Vs LCSC-Sourced MOSFETs

August 24, 2024 by Maya Posch 26 Comments

The fake AliExpress-sourced IRFP460 MOSFETs (Credit: Learn Electronics Repair, YouTube)

These days, it’s super-easy to jump onto the World Wide Web to find purported replacement parts using nothing but the part identifier, whether it’s from a reputable source like Digikey or Mouser or from more general digital fleamarkets like eBay and AliExpress. It’s hardly a secret that many of the parts you can buy online via fleamarkets are not genuine. That is, the printed details on the package do not match the actual die inside. After AliExpress-sourced MOSFETs blew in a power supply repair by [Learn Electronics Repair], he first tried to give the MOSFETs the benefit of the doubt. Using an incandescent lightbulb as a current limiter, he analyzed the entire PSU circuit before putting the blame on the MOSFETs (IRFP460) and ordering new ones from LCSC.

Buying from a distributor instead of a marketplace means you can be sure the parts are from the manufacturer. This means that when a part says it is a MOSFET with specific parameters, it almost certainly is. A quick component tester session showed the gate threshold of the LCSC-sourced MOSFETs to be around 3.36V, while that of the AliExpress ‘IRFP460’ parts was a hair above 1.8V, giving a solid clue that whatever is inside the AliExpress-sourced MOSFETs is not what the package says it should be.

Unsurprisingly, after fitting the PSU with the two LCSC-sourced MOSFETs, there was no more magic smoke, and the PSU now works. The lesson here is to be careful buying parts of unknown provenance unless you like magic smoke and chasing weird bugs.

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Rebuilding The First Digital Personal Computer

August 16, 2024 by Bryan Cockfield 15 Comments

When thinking of the first PCs, most of us might imagine something like the Apple I or the TRS-80. But even before that, there were a set of computers that often had no keyboard, or recognizable display beyond a few blinking lights. [Artem Kalinchuk] is attempting to recreate one of these very early digital computers, the Kenbak-1, using as many period-correct parts as possible.

Considered by many to be the world’s first personal computer, the Kenbak-1 was an 8-bit machine with 256 bytes of memory, using TTL integrated circuits for the logic as there was no commercially available microprocessor available at the time it was designed. For [Artem]’s build, most of these parts can still be sourced including the 7400-series chips and carbon resistors although the shift registers were a bit of a challenge to find. A custom PCB was built to replicate the original, and with all the parts in order it’s ready to be assembled and put into a case which was built using the drawings for the original unit.

Although [Artem] plans to build a period-correct linear power supply for this computer, right now he’s using a modern switching power supply for testing. The only other major components that are different are the status lamps, in this case switched to LEDs because he wasn’t able to source incandescent bulbs that drew low enough current, and the switches which he’s replaced with MX-style keys. We’ll stay tuned as he builds and tests this over the course of several videos, but in the meantime if you’re curious how this early computer actually worked we featured an emulator for it a while back.

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Arduino PLC Keeps The Beat

July 6, 2024 by Bryan Cockfield 12 Comments

For most of our prototype, hobby, or one-off electronics projects it’s perfectly fine to use a development platform like an Arduino Uno or something to that effect. They’re both easy to program and easy to wire up to projects without breaking the bank. But if you step into an industrial setting where reliability is paramount even in places that are noisy, vibrating all the time, hot, or otherwise unpleasant for electronics, you’ll want to reach for a programmable logic controller (PLC) that are much more robust. There is actually a PLC from Arduino, and if you want to dip your toes into the PLC world then take a look at this drum kit based on the Arduino Opta.

With the PLC at the core of the build, it’s on to making the drumming mechanisms themselves. For that, project creator [JC Audio] is using a series of solenoids attached to camera mounts with a custom 3D printed part that allows for quick assembly and disassembly so he can get the positioning of each drum sound just right. The high hat is taken care of by the noise of an internal solenoid, with the other drums striking various real drums and other solid objects in his shops. The solenoids themselves are driven by a solid-state relay expansion module to ensure there’s enough power

While the build doesn’t sit inside a factory and run for years at a time, a musician’s stage is certainly a rough enough environment that we might reach for a PLC over a standard development board for its benefits. The code for this project is available as well at the project’s GitHub page for those looking for a more advanced timekeeper to play along with their music practice, and for more details on why you might choose a PLC for your project take a look at this Arduino vs PLC showdown from a few years ago.

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Automating 3D Printer Support Hardware

June 6, 2024 by Bryan Cockfield 22 Comments

While 3D printers have evolved over the past two decades from novelties to powerful prototyping tools, the amount of support systems have advanced tremendously as well. From rudimentary software that required extensive manual input and offered limited design capabilities, there’s now user-friendly interfaces with more features than you could shake a stick at. Hardware support has become refined as well with plenty of options including lighting, ventilation, filament recycling, and tool changers. It’s possible to automate some of these subsystems as well like [Caelestis Workshop] has done with this relay control box.

This build specifically focuses on automating or remotely controlling the power, enclosure lighting, and the ventilation system of [Caelestis Workshop]’s 3D printer but was specifically designed to be scalable and support adding other features quickly. A large power supply is housed inside of a 3D printed enclosure along with a Raspberry Pi. The Pi controls four relays which are used to control these various pieces hardware along with the 3D printer. That’s not the only thing the Pi is responsible for, though. It’s also configured to run Octoprint, a piece of open-source software that adds web interfaces for 3D printers and allows their operation to be monitored and controlled remotely too.

With this setup properly configured, [Caelestis Workshop] can access their printer from essentially any PC, monitor their prints, and ensure that ventilation is running. Streamlining the print process is key to reducing the frustration of any 3D printer setup, and this build will go a long way to achieving a more stress-free environment. In case you missed it, we recently hosed a FLOSS Weekly episode talking about Octoprint itself which is worth a listen especially if you haven’t tried this piece of software out yet.

Quick & Capable WiFi For Your Nice-Power Supply

May 31, 2024 by Arya Voronova 12 Comments

Rejoice, those of us who have purchased a Nice-Power lab PSU from an Eastern source. Yes, the name might sound like a re-brand of a generic product, maybe you will even see this exact PSU on a shelf at a physical store near you, under a more local brand name and with a fair markup. Nevermind the circumstances, the most important part is that [Georgi Dobrishinov] found a way to add an ESP8266 to the PSU by tapping its internal UART control interface, and wrote a web UI for all your Internet-of-Lab-PSUs needs, called the PowerLinkESP project.

All you need is a Wemos D1 development board, or any other ESP8266 board that has UART pins exposed and handles 5 V input. [Georgi] brings everything else, from pictures showing you where to plug it in and where to tap 5 V, to extensive instructions on how to compile and upload the code, using just the Arduino IDE. Oh, and he tops it off with STLs for a 3D printed case, lest your Wemos D1 board flop around inside.

With [Georgi]’s software, you can monitor your PSU with interactive charts for all readings, export charts in both PNG and CSV, and access a good few features. Your ESP8266’s network uplink is also highly configurable, from an STA mode for a static lab config, to an AP mode for any on-the-go monitoring from your phone, and it even switches between them automatically! The firmware makes your PSU all that more practical, to the point that if you’re about to build an interface for your PSU, you should pay attention to [Georgi]’s work.

Lab PSUs with WiFi integration are worth looking into, just check out our review of this one; smart features are so nice to have, we hackers straight up rewrite PSU firmware to get there if we have to. Oh, and if you ever feel like standardizing your work so that it can interface to a whole world of measurement equipment, look no further than SCPI, something that’s easier to add to your project than you might expect, even with as little as Python and a Pi.