3D-Printed Rotary Dial Keypad Is Wonderfully Useless

March 13, 2019 by Dan Maloney 10 Comments

Right up front, let us stipulate that we are not making fun of this project. Even its maker admits that it has no practical purpose. But this 3D-printed Commodore-style rotary dial keypad fails to be practical on so many levels that it’s worth celebrating.

And indeed, celebrating deprecated technology appears to be what [Jan Derogee] had in mind with this build. Rotary dials were not long ago the only way to place a call, and the last time we checked, pulse dialing was still supported by some telephone central office switchgear. Which brings us to the first failure: with millions of rotary dial phones available, why build one from scratch? [Jan] chalks it up to respect for the old tech, but in any case, the 3D-printed dial is a pretty good replica of the real thing. Granted, no real dial used a servo motor to return the dial to the resting state, but the 3D-printed springs [Jan] tried all returned the dial instantly, instead of the stately spin back that resulted in 10 pulses per second. And why this has been done up VIC-20 style and used as a keypad for Commodore computers? Beats us. It had to be used for something. That the software for the C-64 generates DTMF tones corresponding to the number dialed only adds to the wonderful weirdness of this. Check out the video below.

We’ll hand it to [Jan], he has a unique way of looking at the world, especially when it comes to clocks. We really enjoyed his persistence of phosphorescence clock, and his screw-driven linear clock turns the standard timekeeping UI on its head.

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The Bakery That Runs On Emacs

March 6, 2019 by Rich Hawkes 23 Comments

When it comes to managing ingredients and baking at a professional bakery, we know that most people would turn to an SQL database and emacs. Really, what else do you need? Okay, so maybe there are a few who would think that emacs couldn’t help you with this, so, here’s how [Piers] uses emacs and PostgresSQL to manage the day to day needs at his bakery.

[Piers] had tried a spreadsheet to keep track of things, but didn’t really like it when he had to create a new recipe: “lots of tedious copying, pasting and repetition of formulae” is how he put it. As a ex-professional programmer, [Piers] was familiar with emacs and so set up a daily worksheet in emacs using org-mode. Each morning he runs org-capture to create the template for the day’s work. Some code in the org file (run with org-babel) can run a query on the database. He’s created some code to set up each day’s journal entry and to run the complicated database queries that he needs.

There is a list of things that [Piers] is working on next, including ingredient order management and accounting, but it works for him. And to stop any potential flame wars that might break out, it’s good to mention that the system does just that: It works for him. There are other possibilities. Take a look at Al’s Editor Wars article, or Elliot’s rebuttal, or, ignore the wars and read this article on baking with steam.

Door Springs And Neopixels Demonstrate Quantum Computing Principles

March 6, 2019 by Dan Maloney 7 Comments

They may be out of style now, and something of a choking hazard for toddlers, but there’s no denying that spring doorstops make a great sound when they’re “plucked” by a foot as you walk by. Sure, maybe not on a 2:00 AM bathroom break when the rest of the house is sleeping, but certainly when used as sensors in this interactive light show.

The idea behind [Robin Baumgarten]’s “Quantum Garden” is clear from the first video below: engaging people through touch, sound, and light. Each of the 228 springs, surrounded by a Neopixel ring, is connected to one of the 12 inputs on an MPR121 capacitive touch sensor. The touch sensors and an accelerometer in the base detect which spring is sproinging and send that information to a pair of Teensies. A PC then runs the simulations that determine how the lights will react. The display is actually capable of some pretty complex responses, including full-on games. But the most interesting modes demonstrate principles of quantum computing, specifically stimulated Raman adiabatic passage (STIRAP), which describes transfers between quantum states. While the kids in the first video were a great stress test, the second video shows the display under less stimulation and gives a better idea of how it works.

We like this because it uses a simple mechanism of springs to demonstrate difficult quantum concepts in an engaging way. If you need more background on quantum computing, [Al Williams] has been covering the field for a while. Need the basics? Check out [Will Sweatman]’s primer.

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Reverse Engineering Keeps Keck Telescopes On Track

February 26, 2019 by Dan Maloney 13 Comments

Perched atop a dormant volcano far above the roiling tropical air of the Big Island of Hawai’i sit two of the largest optical telescopes in the world. Each 10-meter main mirror is but a single part of a magnificent machine weighing in at some 400 tons that needs to be positioned with incredible precision. Keeping Keck 1 and Keck 2 in peak operating condition is the job of a team of engineers and scientists, so when the servo amplifiers running the twelve motors that move each scope started to show their age, [Andrew] bit the bullet and rebuilt the obsolete boards from scratch.

The Keck telescopes were built over three decades ago, and many of the parts, including the problematic servo amps, are no longer made. Accumulated wear and tear from constant use and repeated repairs had taken their toll on the boards, from overheated components to lifted solder pads. With only some barely legible schematics of the original amplifiers to go by, [Andrew] reverse engineered new amps. Some substitutions for obsolete components were needed, the PCB design was updated to support SMD parts, and higher-quality components were specified, but the end result is essentially new amplifiers that are plug-in replacements for the original units. This should keep the telescopes on track for decades to come.

Not to sound jealous, but it seems like [Andrew] has a great gig. He’s shared a couple of his Keck adventures before, like the time a failed LED blinded the telescope. He’s also had a few more down-to-earth hacks, like fixing a dodgy LCD monitor and making spooky blinkeneyes for Halloween.

Well-Protected USB Power Strip Makes It Easy To Plug In

February 24, 2019 by Dan Maloney 24 Comments

When we get a new device these days, somewhere in the package is likely to be a wall-wart USB power supply. We look for a place to plug in the little switch-mode dongle, rearrange a few plugs in the mains power strip, and curse its designers for the overly cozy outlet spacing. And all the while that USB-A plug on the power supply cable taunts us with its neat, compact form factor. If only there were a USB power strip.

Unwilling to suffer such indignity any longer, [Scott M. Baker] took matters into his own hands and designed this USB power distribution system. We were surprised to hear that he was unable to find a commercial USB power strip, but even if he had, it likely wouldn’t have had the bells and whistles that he added to his. The circuit went through a couple of revs, but each was focused on protection of the connected USB devices. He included both overcurrent protection, in the form of an electronic fuse built around a TPS2421 hot-swap controller, and overvoltage protection using a crowbar circuit with the usual zener-SCR arrangement. There’s also a transient voltage suppression diode to keep any inductive spikes at bay. Interestingly, each USB outlet has all these protections – it’s not just one protected bus feeding a bunch of USB outlets in parallel, but individual modules with all the circuitry. The modules are gangable and live inside a laser-cut acrylic case. The video below shows the design and build process in some detail.

We have to say that we always learn a lot about circuit design from [Scott]’s projects. You may recall his custom Atari 2600 controller or his dual-port memory retro game console, both interesting and instructive builds in their own right.

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Radiation Detector Eschews Tubes, Uses Photodiode

February 22, 2019 by Dan Maloney 13 Comments

When the topic is radiation detection, thoughts turn naturally to the venerable Geiger-Müller tube. It’s been around for ages, Russian surplus tubes are available for next to nothing, and it’s easy to use. But as a vacuum tube it can be somewhat delicate, and the high voltages needed to run it can be a little on the risky side.

Luckily, there are other ways to see what’s going on in the radioactive world, like this semiconductor radiation detector. [Robert Gawron] built it as a proof-of-concept after having built a few G-M tube detectors before. His solid-state design relies on a reverse-biased photodiode conducting when ionizing radiation hits the P-N junction. The tiny signal is amplified by a pair of low-noise op-amps and output to a BNC connector. The sensor’s analog output is sent to an oscilloscope whose trigger out is connected to a Nucleo board for data acquisition. The Nucleo is in turn connected to a Raspberry Pi for totalizing and logging. It’s a complicated chain, but the sensor appears to work, even detecting alpha emissions from thoriated TIG electrodes, a feat we haven’t been able to replicate with our G-M tube counter.

[Robert]’s solid-state detector might not be optimal, but it has promise. And we have seen PIN diodes used as radiation detectors before, too.

[via Dangerous Prototypes]

Offline E-Paper Typewriter Lets You Write Without Distractions

February 18, 2019 by Dan Maloney 31 Comments

Living and working online is not always easy, especially when it comes to staying focused. All it takes is a moment’s weakness to click on something you shouldn’t and fall down a time-wasting and creativity-killing rabbit hole. Imagine how the creative juices would come to a boil if it were not for the attractive nuisances that lie as close as the next browser tab over.

Creativity-killing online temptations are too much for some to resist, which is why we find this homebrew electronic typewriter so intriguing. Dubbed “SPUDwrite”, or “Single Purpose User Device” by its creator [Lucian], the device is a completely unconnected writing terminal. At its heart, SPUDwrite is just a keyboard attached to an STM32F401 Cortex-M4 microcontroller running MBED and driving an e-paper display. Unfortunately, the refresh rate of the display is too slow to see what you’re typing, so [Lucian] included a small LCD display that shows the current text and where you are in the file. There’s also a thermal receipt printer for those times you just need to hold hardcopy in your hand. [Lucian] introduced the SPUDwrite in an Adafruit show-and-tell session, a clip of which is below the break.

SPUDwrite isn’t perfect, but [Lucian] has plans for version 2, including improving the refresh rate – [Ben Krasnow] might have a few tips on that score. But even as-is, we love the potential for distraction-free creativity while still being able to have an electronic copy of your writing. Our book might finally become a reality with one of these – as long as we can avoid the smartphone.

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