New PCB Revives Ancient Bubble LED Displays

June 11, 2019 by 14 Comments

For those of us who remember LED calculators, the HP 5082-7400 series red “bubble” displays hold a special charm. Available in 3, 4, or 5-digit varieties, these multiplexed 7-segment displays provided countless hours of entertainment to those who would spell upside-down words on their pocket calculators. In case you happen to be lucky enough to have access to a few of these beautiful vintage display sticks, [Gigawipf] has designed a small driver PCB that lets you easily interface them to a modern microcontroller.

At the heart of the board, aimed at either the 5082-7405 or 5082-7415 5-digit modules, are a pair of 74HC595 shift registers in tiny QFN packages. Five lines from one register drive one of the common cathodes for the selected digit, while the other register drives the eight anode lines through 330-Ohm resistors. The boards are slightly smaller than the width of the displays allowing you to stack them seamlessly for more digits, and eight header pins on each allow you to plug them into solderless breadboards for prototyping. The result is easy to drive with some simple code, and [Gigawipf] provides an example for Arduino as part of the project. The Eagle design files are supplied, as well as Gerbers for those who just want to have some boards made. This sounds like a great way to get some of these vintage displays going again.

If you can’t find any of these displays to play, with, you can try making some larger digits from individual surface-mount LEDs.

The Day Hackaday’s Theme Was Broken

June 11, 2019 by 55 Comments

Today at about 10:00 AM Pacific time, Hackaday’s site host had an outage. All websites on the WordPress VIP Go platform were down, and that includes Hackaday. For about 45 minutes you couldn’t load any content, and for a bit more than two hours after that all we could display was a default WordPress theme with an alarmingly bright background.

At first, we were looking at a broken home page with nothing on it. We changed some things around on the back end and we had a black text on white background displaying our latest articles. Not ideal, but at least you could catch up on your reading if you happened to check in right at that time.

But wait! Unintended consequences are a real drag. Our theme doesn’t have comments built into the front page and blog page views, but the WordPress stock themes do. So comments left on those pages were being blasted out to your RSS feeds. I’d like to apologize for that. Once it was reported, we turned off comments on those pages and deleted what was there. But if you have a caching RSS reader you’ll still see those, sorry about that.

As I type this, all should be back to normal. The front end was restored around 1:00 PM Pacific time. We’ve continued our normal publishing schedule throughout, and we hope you have had a good laugh at this debacle. It might be a few days before I’m able to laugh about it though.

Injection Molding With A Hot Glue Gun

June 11, 2019 by 11 Comments

Injection molding is an industrial process used the world over for the quick and economical production of plastic parts. [Nikodem Bartnik] wanted to experiment with this at home, so whipped up some molds and got to work (Youtube link, embedded below).

[Nikodem] produced aluminium molds, using a Dremel-based CNC platform. This allowed for the design to be created in CAD software, and helps with the production of the geometry for both the part, as well as the gates and vents. Having learned about thermal issues with an early attempt, the mold was then clamped in a vice. Wood was used as an insulator to minimise heat lost to the vice.

With this setup, it was possible to mold M5 washers using hot glue, with good surface finish. Later attempts with a larger mold were unsuccessful, due to the glue cooling off before making it through the entire mold. [Nikodem] has resolved to improve his setup, and we look forward to seeing what happens next. We’ve seen others experiment in this area before, too. Video after the break.

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HestiaPi: A Stylish Open Hardware Thermostat

June 11, 2019 by 20 Comments

A common complaint about open hardware and software is that the aesthetic aspects of the projects often leave something to be desired. This isn’t wholly surprising, as the type of hackers who are building these things tend to be more concerned with how well they work than what they look like. But there’s certainly nothing wrong with putting a little polish on a well designed system, especially if you want “normal” people to get excited about it.

For a perfect example, look no further than the HestiaPi Touch. This entry into the 2019 Hackaday Prize promises to deliver all the home automation advantages of something like Google’s Nest “smart” thermostat without running the risk of your data being sold to the highest bidder. But even if we take our tinfoil hat out of the equation, it’s a very slick piece of hardware from a functional and visual standpoint.

As you probably guessed from the name, the thermostat is powered by the Raspberry Pi Zero, which is connected to a custom PCB that includes a couple of relays and a connector for a BME280 environmental sensor. The clever design of the 3D printed case means that the 3.5 inch touch screen LCD on the front can connect directly to the Pi’s GPIO header when everything is buttoned up.

Of course, the hardware is only half the equation. To get the HestiaPi Touch talking to all the other smart gadgets in your life, it leverages the wildly popular OpenHAB platform. As demonstrated in the video after the break, this allows you to use the HestiaPi and its mobile companion application to not only control your home’s heating and air conditioning systems, but pretty much anything else you can think of.

The HestiaPi Touch has already blown past its funding goal on Crowd Supply, and the team is hard at work refining the hardware and software elements of the product; including looking at ways to utilize the unique honeycomb shape of the 3D printed enclosure to link it to other add-on modules.

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BioSentinel Mission Aims To Put Yeast Into Deep Space

June 11, 2019 by 19 Comments

It’s a truly exciting time for space enthusiasts. Humanity is finally shaking itself out of the half-century-long doldrums of deep space exploration and planning a return to the Moon and a push to Mars. Yes, exciting things have happened since the glory days of Apollo. We’ve reached out into the outer planets, drilled holes in asteroids, and made tracks across the face of Mars in an improbably durable rover. We’ve built magnificent space telescopes, created a permanent space station to replace a couple of temporary ones, and put an intricate constellation of satellites into service.

Those are all laudable achievements, but not a single living creature has intentionally achieved approached Earth escape velocity since three astronauts and five mice did it aboard Apollo 17 at 3:46 AM on December 7, 1972. Since then, we’ve all been stuck down here at the bottom of Earth’s gravity well, with only a lucky few of us getting a tease of what space travel is really like with low Earth orbit (LEO) missions.

But if NASA has its way, and certain difficulties with launch vehicles can be ironed out, in 2020 Earthlings will once again slip the surly bonds and make a trip to deep space. Of course those Earthlings will just be cultures of yeast carried into orbit around the Sun on a cubesat, but it’s a start, and it’s a good bet that more complex organisms won’t be far behind.

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Google Home Mini Gets A Headphone Jack

June 11, 2019 by 19 Comments

The Google Home Mini can be a useful home assistant device. It can set reminders, tell you the weather, and even play you music. [Brian] had a few lying around, and decided he wanted to hook one up to a beefier set of speakers. Thus, he installed a headphone jack into the Google Home Mini.

The quick and dirty approach to such a task is to solder a jack to the speaker connections. However, this is an amplified signal, rather than a line level signal suitable for feeding to an amplifier. It’s also mono only. The Google Home Mini uses the TAS5720L mono digital amplifier chip, and some investigation with a logic analyzer and a datasheet allowed [Brian] to figure out the format of the I2C digital audio signal.

With this knowledge in hand, [Brian] hacked in a PCM5102A digital amplifier chip to the Google Home Mini. It can accept audio data in the same format as the TAS5720L, and is readily available on eBay for use with the Raspberry Pi and other maker platforms. With a 3D printed baseplate and some careful soldering, [Brian] was able to integrate the stereo amplifier and a headphone jack neatly into the Google Home.

Unfortunately, the audio output is only two mono channels rather than true stereo, as the device outputs the same data on both left and right  channels in the I2C data. Regardless, the hack works, and [Brian] now has a high-quality voice assistant that he can hook up to a decent pair of speakers.

A Field Guide To Transmission Lines

June 11, 2019 by 120 Comments

The power grid is a complicated beast, regardless of where you live. Power plants have to send energy to all of their clients at a constant frequency and voltage (regardless of the demand at any one time), and to do that they need a wide array of equipment. From transformers and voltage regulators to line reactors and capacitors, breakers and fuses, and solid-state and specialized mechanical relays, almost every branch of engineering can be found in the power grid. Of course, we shouldn’t leave out the most obvious part of the grid: the wires that actually form the grid itself.

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