Author: Bryan Cockfield

1664 Articles

Back To The 90s On Real Hardware

August 22, 2025 by 7 Comments

As the march of time continues on, it becomes harder and harder to play older video games on hardware. Part of this is because the original hardware itself wears out, but another major factor is that modern operating systems, software, and even modern hardware don’t maintain support for older technology indefinitely. This is why emulation is so popular, but purists that need original hardware often have to go to extremes to scratch their retro gaming itch. This project from [Eivind], for example, is a completely new x86 PC designed for the DOS and early Windows 98 era.

The main problem with running older games on modern hardware is the lack of an ISA bus, which is where the sound cards on PCs from this era were placed. This build uses a Vortex86EX system-on-module, which has a processor running a 32-bit x86 instruction set. Not only does this mean that software built for DOS can run natively on this chip, but it also has this elusive ISA capability. The motherboard uses a Crystal CS4237B chip connected to this bus which perfectly replicates a SoundBlaster card from this era. There are also expansion ports to add other sound cards, including ones with Yamaha OPL chips.

Not only does this build provide a native hardware environment for DOS-era gaming, but it also adds a lot of ports missing from modern machines as well including a serial port. Not everything needs to be original hardware, though; a virtual floppy drive and microSD card reader make it easy to interface minimally with modern computers and transfer files easily. This isn’t the only way to game on new, native hardware, though. Others have done similar things with new computers built for legacy industrial applications as well.

Thanks to [Stephen] for the tip!

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Web Dashboard For Zephyr

August 22, 2025 by 6 Comments

Over time, web browsers have accumulated a ton of features beyond what anyone from the 90s might have imagined, from an application platform to file management and even to hardware access. While this could be concerning from a certain point of view, it makes it much easier to develop a wide range of tools. All a device really needs to use a browser as a platform is an IP address, and this project brings a web UI dashboard to Zephyr to simplify application development.

Zephyr is a real-time operating system (RTOS) meant for embedded microcontrollers, so having an easy way to access these systems through a web browser can be extremely useful. At its core, this project provides a web server that can run on this operating system as well as a REST API that can be used by clients to communicate with it. For things like blinking lights this is sufficient, but for other things like sensors that update continuously the dashboard can also use WebSocket to update the web page in real time.

The web dashboards that can be built with this tool greatly reduce the effort and complexity needed to interact with Zephyr and the microcontrollers it typically runs on, especially when compared to a serial console or a custom application that might otherwise be built for these systems. If this is your first time hearing about this RTOS we recently featured a microcontroller-based e-reader which uses this OS as a platform.

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Converting A Sprinkler System To DC

August 22, 2025 by 13 Comments

Famously, Nikola Tesla won the War of the Currents in the early days of electrification because his AC system could use transformers to minimize losses for long distance circuits. That was well before the invention of the transistor, though, and there are a lot of systems that still use AC now as a result of electricity’s history that we might otherwise want to run on DC in our modern world. Sprinkler systems are one of these things, commonly using a 24V AC system, but [Vinthewrench] has done some work to convert over to a more flexible 24 VDC system instead.

The main components of these systems that are set up for AC are solenoids which activate various sets of sprinklers. But these solenoids can take DC and still work, so no major hardware changes are needed. It’s not quite as simple as changing power supplies, though. The solenoids will overheat if they’re fully powered on a DC circuit, so [Vinthewrench] did a significant amount of testing to figure out exactly how much power they need to stay engaged. Once the math was done, he uses a DRV103 to send PWM signals to the solenoids, which is set up to allow more current to pull in the solenoids and then a lower holding current once they are activated.

With a DC power supply like this, it makes it much easier to have his sprinkler system run on a solar powered system as well as use a battery backup without needing something like an inverter. And thanks to the DRV103 the conversion is not physically difficult; ensuring that the solenoids don’t overheat is the major concern here. Another great reason to convert to a DIY sprinkler controller is removing your lawn care routine from an unnecessary cloud-based service.

A Repeater For WWVB

August 7, 2025 by 11 Comments

For those living in the continental US who, for whatever reason, don’t have access to an NTP server or a GPS device, the next best way to make sure the correct time is known is with the WWVB radio signal. Transmitting out of Colorado, the 60-bit 1 Hz signal reaches all 48 states in the low-frequency band and is a great way to get a clock within a few hundred nanoseconds of the official time. But in high noise situations, particularly on the coasts or in populated areas these radio-based clocks might miss some of the updates. To keep that from happening [Mike] built a repeater for this radio signal.

The repeater works by offloading most of the radio components to an Arduino. The microcontroller listens to the WWVB signal and re-transmits it at a lower power to the immediate area, in this case no further than a few inches away or enough to synchronize a few wristwatches. But it has a much better antenna for listening to WWVB so this eliminates the (admittedly uncommon) problem of [Mike]’s watches not synchronizing at least once per day. WWVB broadcasts a PWM signal which is easy for an Arduino to duplicate, but this one needed help from a DRV8833 amplifier to generate a meaningfully strong radio signal.

Although there have been other similar projects oriented around the WWVB signal, [Mike]’s goal for this was to improve the range of these projects so it could sync more than a single timekeeping device at a time as well as using parts which are more readily available and which have a higher ease of use. We’d say he’s done a pretty good job here, and his build instructions cover almost everything even the most beginner breadboarders would need to know to duplicate it on their own.

Real-Time Beamforming With Software-Defined Radio

August 5, 2025 by 13 Comments

It is perhaps humanity’s most defining trait that we are always striving to build things better, stronger, faster, or bigger than that which came before. Taller skyscrapers, longer bridges, and computers with more processors, all advance thanks to this relentless persistence.

In the world of radio, we might assume that a better signal simply means adding more power, but performance can also improve by adding more antennas. Not only do more antennas increase gain but they can also be electronically steered, and [MAKA] demonstrates how to do this with a software-defined radio (SDR) phased array.

The project comes to us in two parts. In the first part, two ADALM-Pluto SDR modules are used, with one set to transmit and the other to receive. The transmitting SDR has two channels, one of which has the phase angle of the transmitted radio wave fixed while the other is swept from -180° to 180°. These two waves will interfere with each other at various points along this sweep, with one providing much higher gain to the receiver. This information is all provided to the user via a GUI.

The second part works a bit like the first, but in reverse. By using the two antennas as receivers instead of transmitters, the phased array can calculate the precise angle of arrival of a particular radio wave, allowing the user to pinpoint the direction it is being transmitted from. These principles form the basis of things like phased array radar, and if you’d like more visual representations of how these systems work take a look at this post from a few years ago.

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The Tape Speed Keyboard

August 4, 2025 by 10 Comments

For those who experienced any part of the 1960s, even if it’s just experiencing the music from that era here in the future, the sound of the Mellotron is immediately recognizable. The Moody Blues were famous for using the tape-based instrument, and the Beatles and David Bowie produced hits with it as well. It’s haunting sounds are still highly prized today, but the complexity, cost, and maintenance requirement for the tape loops and other moving parts can put many musicians off from owning one. But [Japhy Riddle] has built an instrument without these downsides called the Tape Speed Keyboard.

Unlike the Mellotron which used a tape loop for each of its keys, the Tape Speed Keyboard uses only a single cassette tape. As the name implies, it changes the pitch of the sound by modulating the speed of the single tape housed in its own tape deck. The keyboard itself started off life as a Casio MT-35 but since this is a completely analog instrument, it was rewired so each key is connected to a potentiometer whose output voltage is tuned to a specific tape speed. [Japhy] reports that this is similar to tuning an analog piano and the process can be equally temperamental.

With everything electronic working, [Japhy] turned to making this a more acceptable musical instrument. Predictably, turning the motor on and off for each key press came with a bit of delay, causing the sound to come out goofy and muddy. To solve this problem he changed the design to make the tape play continuously rather than start and stop for a key press, and then modified other keys to be on-off switches for sound output. Since cassette tapes have two sides, he can also play either of two sounds in this way.

With the final polish on, the Tape Speed Keyboard is able to produce completely unique compositions that separate it from even the venerable Mellotron. Be sure to check out the video linked below to hear its sound. There have been plenty of other musical projects based around tape decks as well, including this one inspired by the original Mellotron and this tape deck-based guitar effects pedal.

Thanks to [splashbun] for the tip!

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Open-Source, Flexible E-Reader

August 3, 2025 by 30 Comments

Although the most popular e-reader by far is the Kindle, some argue that its primary use isn’t even as an e-reader at all but rather as a storefront for one of the world’s richest companies. For those who want user-focused consumer electronics instead, we’ll often reach for something more untethered, like an off-brand ebook that’s nothing more than an Android tablet with an e-paper display or even a jailbroken Kindle freed from the chains of Amazon. But as our 555 enthusiast community continually points out, even these are overkill for reading books. Enter the ZEReader.

The ZEReader started out as a bachelor’s engineering thesis project by [Anna-Lena Marx], whose goal was an open-source, microcontroller-based e-reader instead of the Linux or Android ones most commonly available. She’s based the firmware around the Zephyr Real-Time Operating System, which is an RTOS geared towards embedded devices. With this as a backbone, it’s trivially easy to implement the e-reader on different microcontrollers as well as use a wide variety of screens. Although the firmware is a work-in-progress, it’s already mature enough to support all of the basics of an e-reader, such as reading .epub files, navigating through the book, and saving progress. It even includes basic HTML parsing.

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