A beige 1960s radio receiver, inset with vacuum tubes

Busted 1960s Vacuum Tube Radio Sings Again

Restoring a vintage radio receiver has the potential to be a fun weekend project, but it pays to know what you’re up against. Especially in the case of vacuum tube electronics, running down gremlins in the circuits isn’t always a straightforward process (also, please mind the high voltage that is present in old vacuum tube equipment). [Mr Carlson] has a knack for getting old radios humming once again, and his repair of a 1960s General Electric barn find radio receiver is a thorough masterclass in vintage electronics servicing.

Seriously, if you’ve got a spare ninety minutes, the video (after the break) is a thorough and unabridged start-to-finish diagnosis and repair of a vintage radio, and an absolute must for anyone interested in doing the same. This barn find radio was certainly showing its age, and it wasn’t long before in-circuit testing found an open filament in one of several vacuum tubes, but the radio was still stubbornly silent. Further testing revealed that the IF transformers were out of spec, requiring servicing and alignment. After fine tuning both the IF and RF sections of the radio, things were definitely looking (and sounding) better.

Fine tuning the various components in the radio went a long way to living up to its “long range” claims, and by the end of the video, it’s almost impossible to find dead air on the AM dial of this radio. If you’ve never had to make fine adjustments to a receiver, especially of this vintage, this video has all the details you’ll need. With the board exposed, [Mr Carlson] also took care of some preventative maintenance, including replacing the original filter capacitor with newer components, as well as replacing the mains safety capacitor with an even safer modern alternative.

We can’t get enough of these restorations, so make sure to check out our detailed write-up of restoring a WWII aircraft radio.

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Eyes On The Prize!

This year’s Hackaday Prize is off to a roaring start. And that’s fantastic, because this year’s challenge is a particularly important one: reducing mankind’s footprint on the earth through better energy collection, better resource use, and keeping what we’ve already got running a little bit longer. Not only is this going to be the central challenge for the next century, but it’s also a playground for hackers like us.

The first phase, Planet-Friendly Power, is in full swing, and we saw some entries on the first day! Were they cheating? Did they have inside information? Nope! Tons of hackers are working on energy efficient ways to drive their projects all along. If your Raspberry Pi data-logger can run on the fuel of the sun, it’s not only better for the world, but it’s a project that you don’t have to remember to change the batteries on.

We’ve got a challenge on recycling, one on reverse engineering stuff to keep it out of the landfill, and one on environmental monitoring and communications infrastructure. These are all great hacker topics, and showcase how folks like us can do our small parts to keep the world running without running it into the ground.

So all of you out there making mesh networks, optimizing solar projects, hacking open closed IoT networks to keep them from obsolescence, or building plastic-sorting robots, this is your chance to get some money and some recognition for your good work.

Thanks again to our Supplyframe overlords for consistently backing and believing in the purpose of the Hackaday Prize, and also to DigiKey who’s been a sponsor of the Prize many years running! Without them, we wouldn’t be able pull this off.

Hack the planet! (Non-ironically, and literally. And get money for doing it.) Hooray for the Hackaday Prize!

Briefcase Computer Is A Glorious Cyberpunk Build

There are plenty of gaming laptops on the market these days, but none quite fit the requirements of one [ParticularlyPippin]. Thus, they set out on building their own portable computer, ending up with a rig in a briefcase with a decidedly cyberpunk feel.

We love this?!

The design relies on desktop components, with the idea being to make a machine with better upgradability than a typical laptop. The briefcase itself is a nice deep-shell unit, and was given a wooden baseboard to hold all the components. It was then provided with standoffs and mountings for a Mini-ITX motherboard, as well as all the necessary add-ons like fans and storage. As in many odd-form-factor builds, a PCI-E riser cable comes in handy to hook up the GPU.

As for the user interface, a USB portable monitor is paired with a mechanical keyboard for the appropriate amount of clackity-clack when hacking out in the field. The icing on the cake, however, are the RGB strip backlights controlled via MSI’s software that really make the final result pop.

It’s a tidy portable build and one that hopefully provides [ParticularlyPippin] with the necessary grunt for their work wherever they can tote a briefcase. It’s not the first homebrew luggable we’ve seen, and it won’t be the last; there’s simply something compelling about the briefcase form factor. If you’re cooking up your own in the home lab, don’t hesitate to drop us a line.

This Motorcycle Uses Water!

Doing the rounds among motorcycle enthusiasts for the last week has been a slightly unusual machine variously portrayed as running on water or sea water. This sounds like the stuff of the so-called “Free energy” fringe and definitely not the normal Hackaday fare, but it comes alongside pictures of a smiling teenager and what looks enough like a real motorcycle to have something behind it. So what’s going on? The answer is that it’s the student project of an Argentinian teenager [Santiago Herrera], and while it’s stretching it a bit to say it runs on sea water he’s certainly made a conventional motorcycle run on the oxygen-hydrogen mix produced from the electrolysis of water. The TikTok videos are in Spanish, but even for non-speakers it should be pretty clear what’s going on.

It’s obvious that the bike is more of a student demonstrator than a road machine, as we’re not so sure a glass jar is the safest of receptacles. But the interesting part for us lies not in the electrolysis but in the engine. it appears to be a fairly standard looking motorcycle engine, a typical small horizontal single. It’s running on a stoichiometric mix of oxygen and hydrogen, something that packs plenty of punch over a similar mix using air rather than oxygen. It would be fascinating to know the effect of this mixture on an engine designed for regular gasoline, for example does it achieve complete combustion, does it burn hotter than normal fuel, and does it put more stress on the engine parts?

You can see something of the bike in the video below the break, and there are a few more videos in his TikTok account. Meanwhile this isn’t the first teenage motorcycle project we’ve featured.

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An 128x64 OLED display with a weird image on it, showing a mouse cursor, date and time in the bottom right corner, and a whole lot of presumably dithered dots

Making Your Own Technically-HDMI OLED Monitor

One day, [mitxela] got bored and decided to build his own HDMI monitor – the unconventional way. HDMI has a few high-speed differential pairs, but it also has an I2C interface used for detecting the monitor’s resolution and issuing commands like brightness control. In fact, I2C is the backbone for a lot of side channels like these – it’s also one of our preferred interfaces for connecting to cool sensors, and in this case, an OLED display!

[mitxela] describes his journey from start to end, with all the pitfalls and detours. Going through the pinout with a broken hence sacrificial HDMI cable in hand, he figured out how to probe the I2C lines with Linux command-line tools and used those to verify that the display was recognized on the HDMI-exposed I2C bus. Then, he turned to Python and wrote a short library for the display using the smbus bindings – and, after stumbling upon an FPS limitation caused by SMBus standard restrictions, rewrote his code to directly talk to the I2C device node, raising FPS from 2 to 5-10.

From there, question arose – what’s the best software route to take? He tried making a custom X modeline on the HDMI port the display was technically attached to, but that didn’t work out. In the end, he successfully employed the Linux capability called “virtual monitors”, and found out about an interesting peculiarity – there was no mouse cursor to be seen. Turns out, they’re typically hardware-accelerated and overlaid by our GPUs, but in [mitxela]’s case, the GPU was not involved, so he added cursor support to the picture forwarding code, too.

With partial refresh, the display could be redrawn even faster, but that’s where [mitxela] decided he’s reached a satisfactory conclusion to this journey. The write-up is a great read, and if videos are more your forte, he also made a video about it all – embedded below.

We first covered the ability to get I2C from display ports 14 years ago, and every now and then, this fun under-explored opportunity has been popping up in hackers’ projects. We’ve even seen ready-to-go breakouts for getting I2C out of VGA ports quickly. And if you go a bit further, with your I2C hacking skills, you can even strip HDCP!

We thank [sellicott] and [leo60228] for sharing this with us!

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The insides of a tube-based noise source

Using A Vacuum Diode To Make The Cleanest Noise Source You’ve Ever Seen

Noise is an annoying but unavoidable part of any engineering project. Fixing noise issues is hard enough, but even just measuring how much noise an amplifier adds to your signal is tricky without proper equipment like a spectrum analyzer. One other thing that makes noise measurements easier is a good, stable noise source that can serve as a reference: you first measure your amplifier without any input, and then measure it again with the noise source connected. Using a few simple formulas you can then calculate how much noise the amplifier produced.

Building a source that generates exactly the amount of noise that you want, no more and no less, is quite a challenge in itself. Several techniques exist, but [Wolfgang] over at the Electronic Projects for Fun blog decided to go for the classic method of using a vacuum diode. He describes the design and analysis of a noise source based on a 2D3B tube in a detailed article.

The tube in question is a special vacuum diode designed to be operated in saturation, meaning at a current high enough to draw away all the electrons generated by the hot filament. When running in this mode, the output current has a noise spectrum that is almost perfectly white, meaning its power level remains constant across the frequency band. [Wolfgang]’s measurements show a deviation of no more than 0.2 dB between 200 kHz and 200 MHz. This is about as close to perfect as you can get, and covers most of the frequency bands of interest to radio amateurs.

The whole project is built up inside a sturdy metal box, with extensive shielding and line filtering to keep undesired signals from contaminating the clean noise signal. A limiter is also an essential component: should the diode’s filament break, the limiter will prevent the sudden transient from reaching the spectrum analyzer and destroying its (very expensive) input stage.

[Wolfgang] has made a few other noise sources based on various components, which he compares on a separate page, although the 2D3B based one is by far the most stable. We’ve also featured a simple pink noise source, which is useful for audio measurement, as well as white noise sources designed to generate random numbers or simply to help you sleep.

Stresses Revealed With A Polariscope

There are a lot of ways that stresses can show up, at least when discussing materials science. Cracks in concrete are a common enough example, but any catastrophic failure in a material is often attributable to some stress that couldn’t be withstood. If you’re interested in viewing those stresses before they result in damage to the underlying material, take a look at this DIY polariscope which can view internal stresses in glass and other clear objects.

The polariscope takes its name from the fact that it uses polarized light to view the internal structure of a transparent object such as glass. When the polarized light passes through glass in a certain way, the stresses show up as lighter areas thanks to the stressed glass bending the light back into view. This one is constructed with a polarizing filter placed in front of an LCD screen set to display a completely white image. When glass is placed between the screen and the filter no light is seen through the polariscope unless there are stresses in the glass. Even placing a force on an otherwise un-stressed glass tube can show this effect, and [Advanced Tinkering], this project’s creator, has several other creations which show this effect in striking detail.

The effect can also be observed as colored areas in other plastic materials as well. It’s an interesting tool which can help anyone who frequently works with glass, but it’s also interesting on its own to see clues left behind from the manufacturing process of various household items. We’ve seen some other investigative methods for determining how other household items are mass produced as well, like this project which breaks down the injection molding process.

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