A man's hand is shown adjusting a black Bakelite dial on the front panel of an instrument. The instrument is contained in a wooden box, and to the left of the box, a thermocouple is inserted into the flame of an alcohol burner.

Reading A Thermocouple With Mercury And A Potentiometer

August 5, 2026 by No comments

If you’ve ever thought about the nomenclature of electrical components, potentiometer stands out as a strange name, etymologically suggesting something like a voltmeter. In fact, the component took its name from a voltage-measuring instrument also named the potentiometer. [Alnwlsn] recently took a look at one such device, which was integrated into a thermometer, and the Weston cell used to calibrate it.

The potentiometer (instrument) has a galvanometer at its heart. One side of the galvanometer is connected to the center lead of a potentiometer (component) which spans a voltage source; the other side is connected to a reference voltage. The potentiometer can be adjusted until no current flows through the galvanometer, at which point both sides match the reference voltage. The reference voltage source can then be replaced with some other source, which can then be measured relative to the reference by adjusting the potentiometer until both the voltages match. The reference voltage source is a Weston cell, which uses two mercury electrodes, one amalgamated with cadmium, to produce a stable 1.018 volt reference; despite being 74 years old, this particular cell still measured at 1.017 volts.

In this case, the potentiometer was made to measure the voltage produced by a thermocouple. After calibrating the potentiometer and connecting an iron-constantan thermocouple, [Alnwlsn] tested it with ice and boiling water, and in each case it proved accurate. In a more extreme test, it captured the temperature difference between the base and the tip of an alcohol flame.

For a bit more on the history of similar devices, check out the history of Weston Electrical Instruments.

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Cell Broadcast: The Modern Emergency Alert System

August 5, 2026 by 13 Comments

Once upon a time, telephones were primarily point-to-point communications systems. There were options for three-way and conference calls out there, but by and large the plain old telephone system was about connecting one handset to another for a direct conversation. For this reason, the telephone was seldom used for mass emergency communications, because it was simply not fit for broadcasting a message to a wide number of people.

However, technology has since changed. Our modern phones are all connected to a big digital over-the-air network, and large swathes of them can be addressed all at once if so needed. This has led to the development of emergency warning systems that use the cellular network, with Cell Broadcast being the most notable iteration.

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Could Camera Hardware Be The Physical Equivalent To USB-C?

August 5, 2026 by 23 Comments

[Mansour] presents an interesting idea in his essay A Common Thread — just as USB-C has become the “One Connector To Rule Them All” in the world of electronics, so too should his projects have a unified physical connection layer. A common thread, if you will.

Specifically, the 1/4″-20 UNC connector that was already on all his camera equipment. Unifying his stuff around that connector wasn’t a bolt from the blue brainwave. By the sounds of it, the idea evolved over time and only became intentional after he’d already started using it.

There’s something to be said for it, though. One thing is the convenience of knowing your various bits and bobs are going to fit together like they were made with LEGO. Another is taking away a whole set of decisions in the design process: it’s going to have a 1/4″-20 UNC fitting, so [Mansour] needs only decide if its going to be tapped into the material or if he’s using an inset or captive bolt.

It isn’t like a 1/4″ bolt is going to introduce a weak point in most things we build — with good hardware it can take a ton or more. On the other hand it’s not exactly resilient to torque, but [Mansour]’s camera bag had the answer to that, too: spring loaded locator pins that drop into holes on the female side to take up the torque. In the photography world, these are ARRI pins. To us they just seem like a good idea.

Maybe you don’t see the point of avoiding redesigning the wheel every time for custom mounts and brackets. After all, that lets you come up the the ideal solution every time. On the other hand, [Mansour] has both simplified his design process and made decades worth of camera-holding objects — everything from tripods to stabilizing gimbals — accessible to all his stuff. It’s an interesting idea, and his full blog post is worth a read, even if it’s not likely the EU is going to force its adoption like it did USB-C. 

Train Simulator Controller: July 2026 Progress Roundup

August 5, 2026 by 2 Comments

For the past three years [Christopher Mitchell] has been working on his replica of a British Rail Class 800 control cab for a physical train simulator, with the July blog update providing many details on the progress.

The Class 800 series of trains is relatively new, having first entered service in the UK in 2017 on the Great Western Railway (GWR). Designed and built by Hitachi as part of their modular AT300 product series, they come in both purely electrical and diesel-electric hybrid configurations to deal with non-electrified rail sections.

British Rail Class 800 in service with LNER in 2023. (Credit: Foulger Rail Photos, Wikimedia)
British Rail Class 800 in service with LNER in 2023. (Credit: Foulger Rail Photos, Wikimedia)

Replicating the experience of driving a train is always a trade-off between what one would like and what is practical or affordable. With only a corner of his apartment to work with, [Christopher] has opted to focus on the instruments and controls in the cab, using real components where possible or building replicas for the remainder.

This entire control panel is to be used with simulators like Train Simulator and Train Sim World, using their controller APIs to both control the in-game train as well as to get feedback to be displayed on the real instruments and the various LEDs, such as those that indicate the state of the external lights. These are all controlled internally via a CAN bus, as is typical.

These instruments include genuine AWS sunflowers, part of the safety system that ensures that a driver has acknowledged a non-clear signal along the track. It’s another nice touch to a control cab simulation that’s shaping up to be rather close to the real deal.

Even if for the average person something like a Densha de Go! copy and associated controllers will likely suffice, there’s a lot to be said for having something closely resembling the real deal for a realistic game, whether it’s a train, car or airplane controller and associated instrumentation.

A Full Motion Video Codec For The Atari ST

August 4, 2026 by 4 Comments

Who says an old dog can’t do new tricks? The Atari ST has got to qualify as an “old dog” 41 years after launch, and if playing Full Motion Video (FMV) cutscenes– from DOS games of a decade later– doesn’t count as a new trick, we’re not sure what does. In this case, [Jonas Eschenburg] is the trainer and his fascinating write-up lets you know exactly how he did it.

Unlike the contemporary and pricier Amiga, Atari’s 68000-based home computer didn’t have any fancy graphics chips; everything has to go through the Motorolla CPU at a blistering 8MHz. Just porting classic DOS games like [Jonas Eschenburg] is doing with Command and Conquer— a title 10 years newer than the ST– is an amazing tour de force. Bringing the cutscenes along for the ride is just bonus, but what a bonus it is.

Granted, [Jonas] has to work within the Atari’s limitations, so it doesn’t quite look the same. The biggest limitation is of course the 16 colour planar graphics on the Atari, compared with 256 colours of chunky goodness that VGA offered. [Jonas] admits that getting good palettes to minimize artifacting is a challenge. Interestingly he’s not showing quite so many blocking artifacts we would expect from the technique he is using: to take advantage of how the ST’s memory is laid out, he’s using a codebook-based codec that splits the image into easily-addressable blocks. Both the palette and the codebook must update continuously as the film plays but that’s still easier on the antique hardware than streaming raw pixel data, which you cannot do. The whole article is absolutely worth a read, and the demo videos generously sprinkled through it are worth a look, too. We’ve included a demo of C&C‘s intro below. If you’re itching to play, the port is on Itch.io.

Speaking of DOS games, did you know the Atari ST can run doom? Multiple versions, even.

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Polystyrene Foam Can Be Gasoline With Some Help

August 4, 2026 by 9 Comments

Styrofoam – or closed-cell extruded polystyrene (XPS) foam if you want to be precise – is one of those materials that is both super versatile for packaging and insulation, but also a menace when it comes to disposal, even if you ignore that the monomer styrene (C8H8) is a known mutagenic toxin. One of the more creative ways to deal with the metric tons of polystyrene waste generated each year is to turn it into gasoline, as demonstrated by [Lowered Expectations] in a recent video.

With polystyrene being just another hydrocarbon polymer, the idea of turning these polymers into the mixture of hydrocarbon chains we call ‘gasoline’ isn’t so crazy. The problem is mostly doing it in a way that makes some economic sense and doesn’t risk turning your domicile into a hazmat risk site or threaten the health of you, your loved ones and the neighborhood.

The method demonstrated in the video uses fairly basic methods involving pyrolysis and distillation. The first step involves dissolving the polystyrene in gasoline that was previously recovered from stale gasoline, which is another dangerously fun science experiment. This creates a thick slurry that’s then put into the distillation flask for the heating phase.

After testing the distillates for spark ignition the useful distillates were combined with fuel stabilizer added. Before tossing this into a gasoline engine tank for further testing, the concerns of auto-polymerization of styrene monomers are addressed, which requires special inhibiters.

Although this mixture runs a gasoline generator just fine, a borescope inspection of the cylinders showed a build-up of a shiny, gummy residue. There’s also the issue that this mixture contains styrene monomers, which are as noted very unhealthy to breathe in from either the fuel or any remaining monomers in the exhaust. Definitely not something to try at home, basically.

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Tearing Down Aircraft Weather Radar Avionics

August 4, 2026 by 1 Comment

If you’re flying high in the sky, it’s useful to know if there’s turbulence, heavy rain, or other nasty weather ahead. Onboard weather radar is a useful tool that pilots use to scope out conditions ahead. [Thomas Scherrer] came into possession of a weather radar display from a vintage aircraft, and decided to tear it apart for our viewing pleasure. 

The unit in question is a Bendix PPI-1 plan position indicator. This particular 1971 example was scored from a McDonnell-Douglas DC9. [Thomas] only has the display itself, not the radar that would feed it or the power supply to turn it on. Still, even just the readout unit is super interesting to look inside. Right off the bat, there’s a neat dimming filter on the front, and the case itself is really beautifully designed for service. The design is very much of its time, full of neat wire harnesses and chunky through-hole components.  There are some neat surprises inside, too, like an interesting device shaped like a triangular prism whose purpose we won’t spoil here.

If you’re wondering what one of these units looks like in action, you can see such an example on YouTube. The display basically lights up in areas where there were stronger radar returns indicating weather to be avoided.

We love radars around these parts, and we feature them all the time. Video after the break.

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