Vacuum Tube Logic Hack Chat

Join us on Wednesday, December 9th at noon Pacific for the Vacuum Tube Logic Hack Chat with David Lovett!

For most of us, circuits based on vacuum tubes are remnants of a technological history that is rapidly fading from our collective memory. To be sure, there are still applications for thermionic emission, especially in power electronics and specialized switching applications. But by and large, progress has left vacuum tubes in a cloud of silicon dust, leaving mainly audiophiles and antique radio enthusiasts to figure out the hows and whys of plates and grids and filaments.

But vacuum tubes aren’t just for the analog world. Some folks like making tubes do tricks they haven’t had to do in a long, long time, at least since the birth of the computer age. Vacuum tube digital electronics seems like a contradiction in terms, but David Lovett, aka Usagi Electric on YouTube, has fallen for it in a big way. His channel is dedicated to working through the analog building blocks of digital logic circuits using tubes almost exclusively. He has come up with unique circuits that don’t require the high bias voltages typically needed, making the circuits easy to work with using equipment likely to be found in any solid-state experimenter’s lab.

David will drop by the Hack Chat to share his enthusiasm for vacuum tube logic and his tips for exploring the sometimes strange world of flying electrons. Join us as we discuss how to set up your own vacuum tube experiments, learn what thermionic emission can teach us about solid-state electronics, and maybe even get a glimpse of what lies ahead in his lab.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, December 9 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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Building This Mechanical Digital Clock Took Balls

In the neverending quest for unique ways to display the time, hackers will try just about anything. We’ve seen it all, or at least we thought we had, and then up popped this purely mechanical digital clock that uses nothing but steel balls to display the time. And we absolutely love it!

Click to embiggen (you’ll be glad you did)

One glimpse at the still images or the brief video below shows you exactly how [Eric Nguyen] managed to pull this off. Each segment of the display is made up of four 0.25″ (6.35 mm) steel balls, picked up and held in place by magnets behind the plain wood face of the clock. But the electromechanical complexity needed to accomplish that is the impressive part of the build. Each segment requires two servos, for a whopping 28 units plus one for the colon. Add to that the two heavy-duty servos needed to tilt the head and the four needed to lift the tray holding the steel balls, and the level of complexity is way up there. And yet, [Eric] still managed to make the interior, which is packed with a laser-cut acrylic skeleton, neat and presentable, as well he might since watching the insides work is pretty satisfying.

We love the level of craftsmanship and creativity on this build, congratulations to [Eric] on making his first Arduino build so hard to top. We’ve seen other mechanical digital displays before, but this one is really a work of art.

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Digital Pregnancy Tests Use LEDs To Read Between The Lines

[Foone] saw a tweet a few weeks ago alleging that digital pregnancy tests are a rip-off. Regular, cheap tests have an absorbent strip running the length of the plastic, with one end exposed for collecting urine. A few excruciating minutes later, a little plastic window in the middle will show one line, two lines, or a plus or minus sign depending on the presence of human chorionic gonadotropin (HCG) in the urine.

As it turns out, at least two digital tests out there are the exact same thing, but with more steps. Instead of a window, they include circuitry that interprets the lines and publishes the result to a little screen in plain English. It can even tell you if you’re doing it wrong by flashing a little RTFM icon.

[Foone]’s teardown reveals a CR1616 coin cell, an 8-bit microcontroller, and a little phototransistor setup that shines LEDs on the strip and reads the incoming light. Unfortunately, the micro is the mask ROM version, so [Foone] can’t reprogram it to run Doom.

The original tweet’s author is probably not alone in assuming that digital tests are supposed to be more accurate somehow. We think the accuracy claim is more about removing the frazzled and/or incompetent human variable from the equation. If the test interprets the results for you, then there’s no mistaking the results, which is technically a higher degree of accuracy. But if you’re in doubt, you get a test from a doctor.

There’s been some discussion about the e-waste aspect of these all these tests — that it’s a shame to produce a microcontroller just to pee on it and throw it away. Sure, you could look at it that way, but unlike a lot of e-waste, these are tools. It’s unfortunate that this is the industry’s idea of higher accuracy, but what should we expect? It’s just testing for the presence of a hormone in urine. Interpreting the results is up to the viewer. We should probably be astounded that they got the cost down to two for $7.

Many people choose to wait a while to start spreading the news. With a Bluetooth-enabled pregnancy test, everyone can find out together.

Thanks for the tip, [Jay]!

LED Art Hack Chat

Join us on Wednesday, July 1 at noon Pacific for the LED Art Hack Chat with Aaron Oppenheimer!

From the first time humans crawled into a cave with a bit of charcoal to sketch scenes from the world around them, artists have been searching for new media and new ways to express themselves. Natural products ruled for thousands of years, with pigments stolen or crafted from nature as well as wood, ivory, bone, and stone for carving. Time and experience guided our ancestors to new and better formulations and different materials, to the point that what qualifies as art and what we’d normally think of as technology have, in many cases, blended into one, with the artist often engineering projects of mammoth proportions and breathtaking beauty.

Aaron Oppenheimer co-founded color+light, a company that specializes in large-scale custom art installations for companies like Google, Nike, and Nissan. One of their projects, the “Oddwood Tree”, is displayed alongside other gigantic art pieces at Area15 on the Las Vegas strip. His most recent project, fluora, is a digital houseplant, with addressable LEDs in the leaves that can be controlled by a smartphone app or respond to stimuli in the environment.

Aaron will join us on the Hack Chat to discuss the LED as artistic medium. Join us as we learn what it takes to make enormous art that’s strong enough to interact with yet responsive enough to be engaging.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, July 1 at 12:00 PM Pacific time. If time zones have you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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Classic Leica Film Camera Turns Digital

While there’s still a market for older analog devices such as vinyl records, clocks, and vacuum-tube-powered radio transmitters, a large fraction of these things have become largely digital over the years. There is a certain feel to older devices though which some prefer over their newer, digital counterparts. This is true of the camera world as well, where some still take pictures on film and develop in darkrooms, but if this is too much of a hassle, yet you still appreciate older analog cameras, then this Leica film camera converted to digital might just attract your focus.

This modification comes in two varieties for users with slightly different preferences. One uses a Sony NEX-5 sensor which clips onto the camera and preserves almost all of the inner workings, and the aesthetic, of the original. This sensor isn’t full-frame though, so if that’s a requirement the second option is one with an A7 sensor which requires extensive camera modification (but still preserves the original rangefinder, an almost $700 part even today). Each one has taken care of all of the new digital workings without a screen, with the original film advance, shutters, and other HIDs of their time modified for the new digital world.

The finish of these cameras is exceptional, with every detail considered. The plans aren’t open source, but we have a hard time taking issue with that for the artistry this particular build. This is a modification done to a lot of cameras, but seldom with so much attention paid to the “feel” of the original camera.

Thanks to [Johannes] for the tip!

Date Clock Requires (Almost) No Interaction

A lot of commercial offerings of technology aimed at helping the elderly seem to do a good job on the surface, but anything other than superficial interaction with them tends to be next to impossible for its intended users. Complicated user interfaces and poor design consideration reign in this space. [7402] noticed this and was able to design a better solution for an elderly relative’s digital day planner after a commercial offering he tried couldn’t automatically adjust for Daylight Savings.

Of course, the clock/day planner has a lot going on under the surface that the elderly relative may not be able to use, but the solution to all of that was to make it update over the network. This task [7402] plans to do remotely since the relative does not live anywhere nearby. It is based on a Raspberry Pi connected to a Uniroi screen which automatically dims but can be switched off by means of a large button in the front. The UI shows the date, time, and a number of messages or reminders in large font in order to improve [7402]’s relative’s life.

This is a great idea for anyone with their own elderly relative which might need something like this but won’t want to interact with the technology other than the cursory glance, but the project is also a great illustration of proper design for the intended users. Commercial offerings often had hidden buttons and complicated menus, but this has none of that, much like this well-designed walker for an elderly Swede.

RTFM: ADCs And DACs

It’s tough to find a project these days that doesn’t use an analog-to-digital converter (ADC) or digital-to-analog converter (DAC) for something. Whether these converters come as built-in peripherals on a microcontroller, or as separate devices connected over SPI, I2C, or parallel buses, all these converters share some common attributes, and knowing how to read the specs on them can save you a lot of headaches when it comes to getting things working properly.

There are some key things to know about these devices, and the first time you try to navigate a datasheet on one, you may find yourself a bit confused. Let’s take a deep dive into the static (DC) properties of these converters — the AC performance is complex enough to warrant its own follow-up article.

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