Should Have Used A Vacuum Tube 555

“You should have used a 555” has become a bit of a meme around these parts lately, and for good reason. There seems to be little that these ubiquitous chips can’t be used for, and in a world where code often substitutes for hardware, it’s easy to point to instances where one could have just used a simple timer chip instead.

Definitely not in the meme category, though, is this overkill vacuum tube 555 timer. It comes to us via [David Lovett], aka [Usagi Electric], who has lately caught the “hollow state” electronics bug and has been experimenting with all sorts of vacuum tube recreations of circuits we’re far more used to seeing rendered in silicon than glass. The urge to replicate the venerable 555 in nothing but vacuum tubes is understandable, as it uses little more than a pair of comparators and a flip-flop, circuits [David] has already built vacuum tube versions of. The only part left was the discharge transistor; a pentode was enlisted to stand in for that vital function, making the circuit complete.

To physically implement the design, [David] built a large PCB to hold the 18 vacuum tubes and the handful of resistors and capacitors needed. Mounted on eight outsized leads made from sheet steel, the circuit pays homage to the original 8-pin DIP form of the 555. The video below shows the design and build process as well as testing of all the common modes of operation for the timer chip.

You can check out more of our coverage of [David]’s vacuum tube adventures, which started with his reverse-engineering of an old IBM logic module. And while he did a great job explaining the inner workings of the 555, you might want to take a deeper dive into how the venerable chip came to be.

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Circuit Sculpture Vibration Sensor

Here’s your useful and beautiful circuit for the day — [New Pew]’s vibration sensor takes manual control of the flip-flop inside a 555 timer and lights an LED in response. Use it to detect those vibrations you expect, like laundry machines, or those you only suspect, like the kind that might be coming from your engine. This gadget isn’t super-precise, but it will probably get the job done.

The vibration-detecting bit is a tiny ball bearing soldered to the spring from an old pen, which is tied between the trigger and ground pins of the 555. When the chip is powered with a 9 V battery, nearby vibrations will induce wiggle in the spring, causing the ball bearing to contact the brass rod and completing the circuit. When this happens, the internal flip flop’s output goes high, which turns on the LED. Then the flip flop must be reset with a momentary button. Check out the build video after the break.

Want to pick up Earthly vibrations? You can detect earthquakes with a homemade variable capacitor, a 555, and a Raspberry Pi.

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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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Restoring An Unusual Piece Of Computing History

Trawling classified ads or sites like Craigslist for interesting hardware is a pastime enjoyed by many a hacker. At a minimum, you can find good deals on used tools and equipment. But if you’re very lucky, you might just stumble upon something really special.

Which is exactly how [John] came into possession of the TRANSBINIAC. Included in a collection of gear that may have once belonged to a silent key, the device is a custom-built solid-state computer that appears to have been assembled in the early 1960s. Featuring a large see-through window not unlike what you might find on a modern gaming computer and a kickstand that tilts it back at a roughly 45° angle, it was obviously built to be shown off. Perhaps it was a teaching aid or even a science fair entry.

After some digging, it looks like the design of the TRANSBINIAC was based on plans published in the January 1960 issue of Electronics Illustrated. Though there are some significant differences. This computer uses eight bistable flip-flip modules instead of the original six, deletes the multiplication circuit, and employs somewhat simplified wiring. Whoever built this machine clearly knew what they were doing, which for the time, is really saying something. This truly unique machine may well have been one of the first privately owned digital computers in the world.

Which is why we’re glad to see [John] trying to restore the device to its former glory. Naturally it’s a little tricky since the computer came with no documentation and its design doesn’t exactly match anything out there. But with the help of other Hackaday.io users, he’s hoping to get everything figured out. It sounds like the first step is to try and diagnose the 2N554 germanium transistor flip-flop modules, as they appear to be behaving erratically. If you have experience with this sort of hardware, feel free to chime in.

We’re supremely proud of the fact that so many of these early computer examples (and the people that are fascinated by them) have recently found their way to Hackaday.io. They’re literally the building blocks on which so much of our modern technology is based on, and the knowledge of how they were designed and operated deserves to live on for future generations to learn from. If it wasn’t for 1960s machines like the TRANSBINIAC or the so-called “Paperclip Computer”, Hackaday might not even exist. It seems like the least we can do is return the favor and make sure they aren’t forgotten.

[Thanks to Yann for the tip.]

Matrix Of Resistors Forms The Hot Hands Behind This Thermochromic Analog Clock

If you’re going to ditch work, you might as well go big. A 1,024-pixel thermochromic analog clock is probably on the high side of what most people would try, but apparently [Daniel Valuch] really didn’t want to go to work that day.

The idea here is simple: heat up a resistor by putting some current through it, lay a bit of thermochromic film over it, and you’ve got one pixel. The next part was not so simple: expanding that single pixel to a 32 by 32 matrix.

To make each pixel square-ish, [Daniel] chose to pair up the 220-ohm SMD resistors for a whopping 2,048 components. Adding to the complexity was the choice to drive them with a 1,024-bit shift register made from discrete 74LVC1G175 flip flops. With the Arduino Nano and all the other support components, that’s over 3,000 devices with the potential to draw 50 amps, were someone to be foolish or unlucky enough to turn on every pixel at once. Luckily, [Daniel] chose to emulate an analog clock here; that led to additional problems, like dealing with cool-down lag in the thermochromic film when animating the hands, which had to be dealt with in software.

We’ve seen other thermochromic displays before, including recently with this temperature and humidity display. This one may not be the highest resolution display out there, but it’s big and bold and slightly dangerous, and that makes it a win in our book.

3D Print Your Very Own Mechanical Computer

Most Hackaday readers are familiar with computers from the 70s and 80s, but what about ones even older than that? The Digi Comp 1 was a commercially available computer from the 1960s that actually cost less than a modern-day microcontroller. The catch? It was mechanical rather than electrical. Thanks to retro-wizard [Mike Gardi], now anyone can build a replica of one.

Admittedly the Digi Comp 1 was more of a toy than a tool, but it was still a working computer. It contained three flip-flops (memory) and had a lever that acted as a clock, allowing the user to perform boolean operations and some addition and subtraction. Certainly not advanced, but interesting nonetheless. [Mike]’s version of the Digi Comp 1 has an extra bit when compared to the original and includes some other upgrades, but largely remains faithful to the original design.

If you want to print one of these on your own, [Mike] has made all of the files available on Thingiverse. He has also experimented with other mechanical computers as well, including the sequel Digi Comp 2. We’ve seen some recent interest in that mechanical computer lately as well.

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Circuit VR: Redundant Flip Flops And Voting Logic

We are somewhat spoiled because electronics today are very reliable compared to even a few decades ago. Most modern electronics obey the bathtub curve. If they don’t fail right away, they won’t fail for a very long time, in all likelihood. However, there are a few cases where that’s not a good enough answer. One is when something really important is at stake — the control systems of an airplane, for example. The other is when you are in an environment that might cause failures. In those cases — near a nuclear reactor or space, for example, you often are actually dealing with both problems. In this installment of Circuit VR, I’ll show you a few common ways to make digital logic circuits more robust with some examples you can run in the Falstad simulator in your browser.

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