Nixies Adorn A Cold War Relic To Make A Geiger Clock

February 27, 2020 by Dan Maloney 22 Comments

Say what you will about the centrally planned economies of the Soviet bloc during the Cold War, but their designs had a brutal style all their own. When one comes across an artifact from that time, like a defunct Polish Geiger counter from 1971, one celebrates that style the only way possible: by sticking Nixies tubes on it and making it into a Geiger clock.

Right off the hop, we’ve got to say that we’re in love with the look of [Tom Sparrow]’s build. And we’ll further stipulate that most of the charm comes from the attractive Bakelite case of the original Geiger counter. This looks like the real deal, with the marbleized look presumably caused by different color resins mixing in the mold. [Tom] did an admirable job bringing back the original shine with some polish and elbow grease; no doubt the decades had taken their toll on the original shine. The meter was gutted to make room for the clockworks, which is an off-the-shelf Nixie module. The tubes stick through holes drilled in the top; a pair of LEDs adorn the front panel and an incandescent bulb provides a warm glow behind the original meter. Combined with the original rotary switch and labels, the whole thing has a great look that’s perfect for a desk.

We’ve featured a lot of retro-classic Nixie builds, from digitizing a 1940s radio to a 1970s multimeter turned into a dice-roller. As for Nixie clocks, we’re just glad to take a break from the Nixie steampunk trend for a bit.

[via Dangerous Prototypes]

Why Some Chips Have Inconvenient Pinouts

February 17, 2020 by Donald Papp 29 Comments

If you’ve ever handled a chip with a really strange or highly inconvenient pinout and suspected that the reason had something to do with the inner workings, you may be interested to see [electronupdate]’s analysis of why the 4017 Decade Counter IC has such a weirdly nonintuitive pinout. It peeks into an IC design dating from the 1970s to see an example of the kind of design issues that can affect physical layout.

Inside the 4017. Want to make sense of how lines and shapes on a silicon wafer make an IC work? With the right teachers, it’s simple.

In the case of the 4017, once decapped and the inner workings exposed, things became more clear. Inside the chip are a bunch of flip-flops and NAND gates, laid out in a single layer. Some of the outputs (outputs 5 and 1 for example, physically on pins 1 and 2 respectively) share the same flip-flop.

The original design placed the elements in a way that made the most logical sense for routing and layout, which resulted in nice and tidy inner workings but an apparently illogical pinout. A lot of this is probably feeling familiar to anyone who has designed and routed a single-layer PCB, where being limited to one layer makes it important to get the most connections as directly near one another as possible.

Chip design has of course come a long way since the 70s, but there is forever some level of trade-off to be made between outward tidiness and inner design harmony. The next time you’re looking at a part with an apparently illogical pinout, there’s a fair chance it makes far more sense on the inside.

If any of you are interested in decapping ICs yourselves to see what’s inside, we saw that it’s possible with commonly available chemicals, not just nasty ones.

Continue reading “Why Some Chips Have Inconvenient Pinouts” →

Concrete Solder Squid Is A Solid Solution

February 12, 2020 by Kristina Panos 12 Comments

Although it’s possible to buy a soldering setup out of the box, the one that works for you will likely develop over time. Honestly, it may never stop evolving. Sure, you can start with el-cheapo helping hands or a nice hobby vise, but it probably won’t end there. Why? Because no one of these tools will be right for all applications, unless you plan to solder the same thing over and over again. Sometimes it’s just easier to alligator clip a board in place than to slowly manipulate the jaws of a vise, but those helping hands have such a limited range of motion.

Have you been meaning to build a soldering squid out of coolant hose because that stuff just looks so dang cool and bendy? Well, then let Hackaday alum [JeremySCook] show you how it can be done. A few years ago he built a similar squid with a wooden base, but it just isn’t heavy enough, so he redesigned it with a concrete base. He took the opportunity to make some nice tweaks, like zip-tying a small PC fan and 9 V to make an endlessly repositionable ventilation system, and adding a big clip in the back for extra stability while soldering. And of course, threading the solder spool on to one of the hoses is genius.

If you follow [Jeremy] at all, you know he’s been playing around with concrete for a while now, and it’s neat to see him cement his devotion to the stuff by using it in the pursuit of better tools. He’s got the files for the printed mold up on GitHub, and the build video after the break should be all set up by now.

Not custom enough for you? Fire up that printer and make your own ball and socket arms.
Continue reading “Concrete Solder Squid Is A Solid Solution” →

A Modern Take On The “Paperclip Computer”

February 8, 2020 by Tom Nardi 44 Comments

Back in 1968, a book titled “How to Build a Working Digital Computer” claimed that the sufficiently dedicated reader could assemble their own functioning computer at home using easily obtainable components. Most notably, the design utilized many elements that were fashioned from bent paperclips. It’s unclear how many readers actually assembled one of these so-called “Paperclip Computers”, but today we’re happy to report that [Mike Gardi] has completed his interpretation of the 50+ year old homebrew computer.

The purist might be disappointed to see how far [Mike] has strayed from the original, but we see his embrace of modern construction techniques as a necessary upgrade. He’s recreated the individual computer components as they were described in the book, but this time plywood and wheat bulbs have given way to 3D printed panels and LEDs. While the details may be different, the end goal is the same: a programmable digital computer on a scale that can be understood by the operator.

To say that [Mike] did a good job of documenting his build would be an understatement. He’s spent the last several months covering every aspect of the build on Hackaday.io, giving his followers a fantastic look at what goes into a project of this magnitude. He might not have bent many paperclips for his Working Digital Computer (WDC-1), but he certainly designed and fabricated plenty of impressive custom components. We wouldn’t be surprised if some of them, such as the 3D printed slide switch we covered last month, started showing up in other projects.

While the WDC-1 is his latest and certainly greatest triumph, [Mike] is no stranger to recreating early digital computers. We’ve been bringing you word of his impressive replicas for some time now, and each entry has been even more impressive than the last. With the WDC-1 setting the bar so high, we can’t wait to see what he comes up with next.

Continue reading “A Modern Take On The “Paperclip Computer”” →

A 3.3 V Tube Preamp Without An Inverter

February 8, 2020 by Jenny List 34 Comments

If you’ve ever worked with vacuum tubes, you’ll probably have a healthy appreciation for high voltage power supplies. These components require higher potentials to get those electrons moving, or so we’re told. It’s not the whole truth though, as [Albert van Dalen] demonstrates with his tube preamplifier running from only 3.3 V. If your first thought is that he must have made a flyback converter to step that voltage up to something more useful then you’re in for a surprise, because the single 6J6 pentode really does run from just 3.3 volts. Even its heater, normally supplied with 6.3 V, takes the lower voltage.

The circuit appears at first sight to be a conventional single-ended design, but closer examination reveals a grid bias circuit more reminiscent of a bipolar transistor. This results in a positive grid voltage rather than the more usual negative, and an unusually high 0.3 mA grid current. The cathode current is only 0.15 mA, but the preamplifier delivers a 3.5x gain. There is more detail on his website.

It would be interesting to subject this circuit to a full audio analysis and comparison with a more conventional design. As with so much in the world of audio there’s some smoke and mirrors around what constitutes the so-called “valve sound”, and it’s a question whether the satisfaction comes through the sound itself or the bragging rights of having a unit with a vacuum tube on show. Still, this is a simple enough design which takes few resources to build, so we look forward to seeing further experimentation. Careful though – down the vacuum audio route can lie folly.

An Arcade Cabinet With Displays To Spare

January 31, 2020 by Tom Nardi 15 Comments

We’ve all got a pretty good mental image of what an arcade cabinet looks like, so you probably don’t need to be reminded that traditionally they are single-screen affairs. But that idea dates back to when they were built around big and bulky CRT displays. Now that we have modern LCD, LED, and OLED panels, who says you have to follow the old rules?

That’s precisely the sort of out of the box thinking that lead [Al Linke] to build this unique multi-display arcade cabinet. The game itself is still played on a single screen, but several smaller sub-displays are dotted all around the cabinet to indicate various bits of ancillary information. Are they necessary? Hardly. But we can’t deny it’s a clever idea, and we wouldn’t be surprised if we start seeing something similar in other DIY cabinets.

The build started with a commercially available cabinet from Arcade1Up, which at this point are popular enough that some of the Big Box retailers have them in stock. All of the electronics except for the display were stripped out, and replaced with a Dell OptiPlex 9020 computer and high-quality joysticks and buttons. [Al] then installed his various displays all over the cabinet, including a gorgeous LED marquee that we’ve featured previously.

So what do all these little screens do? [Al] explains them in the video after the break, but the general idea is that they provide contextual information about the game you currently have loaded up. A two-color OLED display shows the name of the game and what it’s rated, while a seven segment LED display shows the year the game was released. The displays are located both by the controls and where you’d expect the coin slot to be, so whether you’re actively playing or across the room, you can see all the information.

We’re always amazed to see how builders find ways to make their own personal arcade cabinets stand out. While it’s an idea that at this point we’ve seen quite a lot of, no two projects have ever been quite the same.

Continue reading “An Arcade Cabinet With Displays To Spare” →

Water Switch Lamp Illuminates Current Flow

January 31, 2020 by Kristina Panos 25 Comments

They always told you not to mix water and electricity. And while yes, that is good general advice regarding the two, you won’t rip a hole in the fabric of space-time should you go about it responsibly. Water will conduct electricity, so why not use it to switch on a lamp?

[Manvith Subraya]’s Hydro Lamp is, among other things, a reminder not to let Big Switch dim your idea of what’s possible with simple components. Switches don’t have to be complex, and some of the most reliable switches are pretty simple — the reed switch and the mercury tilt switch are good examples. By salinating the water at a ratio of 1:1, [Manvith] ensures power will flow through the acrylic tank, completing the circuit and lighting the 20W LEDs in both ends.

The brief demo video after the break sheds light on an interesting aspect of using water as a tilt switch — it’s not instantaneous. As he slowly moves the lamp from vertical to horizontal and back again, the light brightens and dims with the tide of electrons. We think it would be interesting to build a motorized frame that takes advantage of this for mood lighting purposes, especially if there were a few LEDs positioned behind the water.

Water is often used to explain the basic principle of current flow and the relationship dynamics of voltage, current, and resistance. As we saw in this water computer, the concept flows all the way into logic gates.

Continue reading “Water Switch Lamp Illuminates Current Flow” →