A Pi Pico on a breakout board inside a Busch 2090 educational computer

Pi Pico Becomes SRAM For 1981 Educational Computer

September 10, 2023 by 18 Comments

Ever since the Raspberry Pi Pico was introduced in early 2021 we’ve seen the tiny Pi being used for an astonishing variety of applications. It has powered countless clocks, gadgets, games, and accessories for all kinds of computers old and new. [Michael Wessel] has recently added an interesting new application in the “old computer” category, by turning a Pico into a 2114 SRAM emulator for his Busch 2090, an educational computer system from 1981.

The pinout of the classic 2114 SRAM chip is quite simple: ten address lines, four data lines, Write Enable and Chip Select. Since the 3.3 V Pico is more or less 5V tolerant, you could directly connect these signals to its GPIO ports, but [Michael] considered it more reliable to use level shifters between the two voltage domains. He experimented with a few standard level shifter circuits, but quickly realized he had to take the 33 kΩ pulldown resistors on the Busch 2090’s address bus into account. By just adding a couple of resistors to the Pico’s ports he could make completely passive level shifters, which worked just fine since the system’s clock frequency is only 500 kHz.

[Michael] demonstrates his RAM replacement in the video below, with a neat set of blinkenlights showing the data being shuttled around in real time. He has plans to make a proper PCB for his project, as well as to enable all kinds of neat features by modifying the system’s RAM in real time. This is of course not limited to the Busch 2090: the 2114 chip was widely used in the 1980s, so the PicoRAM can probably be used in many other systems of the era. Code for the Pi is available on GitHub if you’re interested in trying this for yourself. If you’d like to find out what programming a Busch 2090 feels like, you can emulate one using an Arduino.

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When Tail Lights Lose Touch With Reality

September 9, 2023 by 129 Comments

To study the history of the automobile is to also be a student of technological progress — as with each decade’s models come new innovations to make them better handling, more corrosion-resistant, faster, more efficient, or whatever the needs of the moment dictate. But sometimes that technological advancement goes awry and works against the motorist, making for a vehicle that’s substantially worse than what went before. [FordTechMakuloco] has a video with an example in a Ford pickup, which we believe deserves to be shared.

The problem with the vehicle was simple enough, indeed it’s one we’ve had in the past ourselves. Water got into a tail light, and corroded some connectors. The difference with this Ford though was that such a simple fault took out the whole car, and that the fix for a simple tail light cost $5600. The first was due to a vehicle-wide CAN bus going down due to the electrical short, and the second was due to the assembly containing an assortment of wiring and modules which couldn’t be replaced separately. These included some form of side-facing parking radar, a component unnecessary for operation of the light itself. Some relatively straightforward design and component supply decisions such as separating subsystems across multiple CAN busses, ensuring individual modules are separately available, and even designing connectors to face downwards and self-drain, could have fixed it, but the automaker chose instead to build in some planned obsolescence. Would you buy a Ford truck after seeing the video below the break?

We’ve written here before about how automotive design has taken this wrong path, and even advanced a manifesto as to how they might escape it. This Ford tail light seems to us an egregious example of electronics-as-the-new-rust rendering what should be a good vehicle into a badly designed piece of junk, and honestly it saddens us to see it. Oddly, there was once a time when a Ford truck was about as good as you could get.

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The WebStick Is A Small, Cheap NAS

September 9, 2023 by 23 Comments

The ESP8266 was one of the first chips that provided wireless functionality at a cost low enough to be widely popular for small microcontroller projects. This project uses one to provide rapid, small, and inexpensive network-attached storage (NAS) capabilities wherever you happen to go.

With an ESP12F board at the heart to provide network connectivity, the small device also hosts a micro SD card slot and a USB-A port to provide power and programming capabilities for the device. It’s Arduino-compatible, and creator [tobychui] has provided the firmware source code necessary to bring it up on your network and start serving up files. Originally intended for people to host web services without experience setting up all of the tools needed for it, there’s services for storing and streaming music and video over the network as well.

While it includes a lot more functionality than is typically included on a NAS, [tobychui] notes that with a library, something like WebDAV could be added to provide more traditional NAS capabilities. As it stands, though, having networked storage with web hosting capabilities on a PCB with a total cost of around $5 is not something to shy away from. If you’re looking for something a little more powerful for your home network, take a look at this ARM-based NAS instead.

A ceiling-mounted model of the Solar System

Ceiling-Mounted Orrery Is An Excercise In Simplicity

September 9, 2023 by 29 Comments

Ever since humans figured out that planets move along predetermined paths in the heavens, they have tried to make models that can accurately predict their motion. Watchmakers and astronomers worked together to create orreries: mechanical contraptions that illustrate the positions of all planets and the way they move over time through complex gear systems. [Illusionmanager] continues the orrery tradition but uses a different approach: he built a beautiful ceiling-mounted model of our Solar System without a gearing system.

The mechanism that makes his Solar System tick is deceptively simple. All planets can move freely along their orbit’s axis except Mercury, which is moved along its orbit by a motor hidden inside the Sun. Once Mercury has completed a full revolution, a pin attached to its arm will begin pushing Venus along with it. After Venus has completed a full circle, its own pin will pick up Earth, and so on all the way to Neptune. Neptune is then advanced to its correct location as reported by NASA, after which Mercury’s motion is reversed and the whole procedure is repeated in the opposite direction to position Uranus.

Cycling through the entire Solar System in this way takes a long time, which is why the planets’ positions are only updated once a day at midnight. An ESP32, also hidden inside the Sun, connects to the internet to retrieve the correct positions for the day and drives the motor. The planet models, sourced from a museum shop, are hanging from thin aluminium tubes attached to wooden mounts made with a desktop CNC machine.

[Illusionmanager] made a detailed Instructables page showing the process of making a miniature version of the mechanism using just laser-cut wooden parts, as an update to a version we featured earlier. We really like the simplicity of this design, which stands in stark contrast to the huge gear trains used in more traditional orreries.

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Linux Fu: Build A Better Ls

September 8, 2023 by 27 Comments

Ask someone to name all the things they can find in a room. Only a few will mention air. Ask a Linux command line user about programs they use and they may well forget to mention ls. Like air, it is seemingly invisible since it is so everpresent. But is it the best it can be? Sure, you can use environment variables and aliases to make it work a little nicer, but, in fact, it is much the same ls we have used for decades. But there have always been moves to make better ls programs. One of them, exa, was recently deprecated in favor of one of its forks, eza.

One thing we liked about eza is that it is a single file. No strange installation. No multiple files to coordinate. Put it on your path, and you are done. So installation is easy, but why should you install it?

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Wien Bridge Oscillator Drives Distortion Into The Floor

September 8, 2023 by 12 Comments

It’s not often that a single photo can tell you pretty much everything you need to know about a project, but the spectrum analyzer screenshot nearby is the perfect summary of this over-the-top low-distortion audio oscillator build. But that doesn’t mean there’s not a ton of interesting stuff going on with this one, so buckle up.

One spike at the fundamental and not much more.

The project is by [Basin Street Design], who doesn’t really offer much by way of inspiration for this undertaking, nor a discussion on what this will be used for. But the design goals are pretty clear: build an oscillator with as little distortion as possible across the audio frequency range.

The basic circuit is the well-known Wien bridge oscillator where the R-C pairs are switched in and out of the feedback loop to achieve frequency range control. This was accomplished with rotary switches rebuilt from their original configuration in a Heathkit IG-18 sine/square wave generator, a defunct instrument that was gutted and used as an enclosure for this build. There are a lot of other treats here, too, like the automatic gain control (AGC) that uses a homebrew voltage-controlled resistor made from an incandescent lamp and a cadmium sulfide photoresistor glued inside a piece of brake line, and an output attenuator made from discrete resistors that drops the output in 10 dB steps while maintaining an overall 75-Ohm impedance.

But at the end of the day, it all comes down to that single spike on the spectrum analyzer, with no apparent harmonics. To make sure there wasn’t something hiding down in the noise, [Basin Street] added a notch filter to lower the fundamental by 60 dB, allowing the spectrum analyzer sensitivity to be cranked way up. Harmonics were visible, but so far down into the noise — as low as -115 dBc — that it’s hardly worth mentioning.

There’s a lot more detail in this one, so dive in and enjoy. If you want another take on Wien bridge circuits, check out this recent LM386-based oscillator. Just don’t expect such low distortion with that one.

An aluminum box sits on a workbench. It is open and has a message saying "I Love You!" inserted in a wooden slot. There is a switch with a yellow LED on the front and a small compartment to the left of the wooden slot to store paper.

Share Your Feelings Like A Spy

September 8, 2023 by 13 Comments

While hackers can deftly navigate their way through circuit diagrams or technical documentation, for many of us, simple social interactions can be challenge. [Simone Giertz] decided to help us all out here by making a device to help us share our feelings.

Like an assignment in Mission: Impossible, this aluminum box can convey your confessions of love (or guilt) and shred them after your partner (or roommate) reads the message. The box houses a small shredder and timer relay under a piece of bamboo salvaged from a computer stand. When the lid is opened, a switch is depressed that starts a delay before the shredder destroys the message. The shredder, timer, and box seem almost made for each other. As [Giertz] says, “Few things are more satisfying than when two things that have nothing to do with each other, perfectly fit.”

While seemingly simple, the attention to detail on this build really sets it apart. The light on the front to indicate a message is present and the hinged compartment to easily clean out shredded paper really make this a next-level project. Our favorite detail might be the little space on the side to store properly-sized paper and a marker.

While the aluminum box is very industrial chic, we could see this being really cool in a vintage metal lunch box as well. If you’re looking for other ways to integrate feelings and technology, checkout how [Jorvon Moss] brings his bots to life or how a bunch of LEDs can be used to express your mood.

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