A picture showing acupuncture needles wedged into the inside of the payment terminal

Aaron Christophel Brings DOOM To Payment Terminal

March 1, 2023 by 9 Comments

Payment terminals might feel intimidating — they’re generally manufactured with security in mind, with all manner of anti-tamper protections in place to prevent you from poking around in the hardware too much. But [Aaron Christophel] thinks that level of security isn’t aren’t always in practice however, and on his journey towards repurposing devices of all kinds, has stumbled upon just the terminal that will give up its secrets easily. The device in question is Sumup Solo terminal, a small handheld with a battery, LTE connection and a payment card slot – helping you accept card payments even if you’re on the go.

Now, this terminal has security features like the anti-tamper shield over the crucial parts of the device, leading to payment processing-related keys being erased when lifted. However, acupuncture needles, a tool firmly in [Aaron]’s arsenal, helped him reach two UART testpoints that were meant to be located under that shield, and they turned out to be all that a hacker needed to access the Linux system powering this terminal. Not just that, but the UART drops you right into the root shell, which [Aaron] dutifully explored — and after some cross–compilation and Linux tinkering, he got the terminal to, naturally, run Doom.

The video shows you even more, including the responsible disclosure process that he went through with Sumup, resulting in some patches and, we hope, even hardware improvements down the line. Now, the payment processing keys aren’t accessible from the Linux environment — however, [Aaron] notes that this doesn’t exclude attacks like changing the amount of money displayed while the customer is using such a terminal to pay.

If you’d like to take a closer look at some of the hardware tricks used in these secure devices, we did a teardown on one back in 2019 that should prove interesting.

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Brand New Colecovision Console – On A Breadboard

March 1, 2023 by 4 Comments

The Colecovision console from the early 1980s is probably not the most memorable platform of its era, but it retains a retrocomputing following to this day. The original hardware can be a bit pricey in 2023, so [nanochess] has built one of his own on a breadboard. It’s fully functional from original Colecovision cartridges, and we see it in the video below the break running Frogger.

Behind the mess of wires is a surprisingly simple circuit with only a few logic chips beyond the Z80 processor, the various memory and EPROM chips, and the video and sound chips. We’re told the complexity is considerably reduced by the use of a Texas Instruments  TMS9118 video controller instead of a 9918.

Had we been building it we would probably have taken the less brave step of using color coded wires for the various signals, because we remember the fun and games associated with wiring old-style 8-bit computers by hand only too well. But we have to admit that it reminds us of a lost youth working out Z80 address decoder schematics, so it’s very pleasing to see one built today.

If you’re hungry for more Coleco goodness, this isn’t the first home made Colecovision we’ve brought you.

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A man sits in front of a wooden table. There is a black box with a number of knobs hand-labeled on blue painter's tape. A white breadboard with a number of wires protruding from it is visible on the box's left side. An oscilliscope is behind the black box and has a yellow waveform displaying on its screen.

A More Expressive Synth Via Flexure

February 28, 2023 by 13 Comments

Synthesizers can make some great music, but sometimes they feel a bit robotic in comparison to their analog counterparts. [Sound Werkshop] built a “minimum viable” expressive synth to overcome this challenge. (YouTube)

Dubbed “The Wiggler,” [Sound Werkshop]’s expressive synth centers on the idea of using a flexure as a means to control vibrato and volume. Side-to-side and vertical movement of the flexure is detected with a pair of linear hall effect sensors that feed into the Daisy Seed microcontroller to modify the patch.

The build itself is a large 3D printed base with room for the flexure and a couple of breadboards for prototyping the circuits. The keys are capacitive touch pads, and everything is currently held in place with hot glue. [Sound Werkshop] goes into detail in the video (below the break) on what the various knobs and switches do with an emphasis on how it was designed for ease of use.

If you want to learn more about flexures, be sure to checkout this Open Source Flexure Construction Kit.

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Arc Overhangs In PrusaSlicer Are A Simple Script Away

February 28, 2023 by 21 Comments

Interested in the new hotness of printing previously-impossible overhangs? You can now integrate Arc Overhangs into PrusaSlicer and give it a shot for yourself. Arc overhangs is a method of laying filament into a pattern of blossoming concentric rings instead of stringing filament bridges over empty space (or over supports).

These arcs are remarkably stable, and result in the ability to print overhangs that need to be seen to be believed. We covered this clever technique in the past and there are now two ways for the curious hacker to try it out with a minimum of hassle: either run the Python script on a G-code file via the command line, or integrate the functionality into PrusaSlicer directly by adding it as an automatic post-processing script. The project’s GitHub repository has directions for both methods.

Here’s how it works: the script looks for layers with a “bridge infill” tag (which PrusaSlicer helpfully creates) and replaces that G-code with that for arc overhangs. It is still a work in progress, so keep a few things in mind for best results. Arc overhangs generally work best when the extruded plastic cools as fast as possible. So it is recommended to extrude at the lowest reliable temperature, slowly, and with maximum cooling. It’s not fast, but it’s said to be faster than wrestling with supports and their removal.

A few things could use improvement. Currently the biggest issue is warping of the arc overhangs when new layers get printed on top of them. Do you have a solution or suggestion? Don’t keep it to yourself; discuss in the comments, or consider getting involved in the project.

Trying (and Failing) To Restore A 1970s CDC 10MB Hard Drive

February 28, 2023 by 33 Comments

One fun aspect of 1970s-era hard disk drives is that they are big, clunky and are fairly easy to repair without the need for a clean room. A less fun aspect is that they are 1970s-era HDDs and thus old and often broken. While repairing a CDC 10 MB HDD for the upcoming VCF East event, the folks over at [Usagi Electric], this led to quite a few struggles, even after a replacement 14″ platter was found to replace the crashed platter with.

These CDC HDDs are referred to as Hawk drives, and they make the associated 8-bit Centurion  TTL logic-based computers so much faster and easier to work with (for a 1970s system, of course). Despite the large size of the components involved and the simple, all through-hole nature of the PCBs, issues that cropped up ranged from corroded DIP switches, to head alignment sensors, a defective analog board and ultimately a reported bad read-write head.

Frustratingly, even after getting the platters to spin up and everything moving as intended, it would seem that the remaining problem is that of possibly bad read-write heads, as in plural. Whether it’s due to age, previous head crashes onto platters, or something else, assembling a working Hawk drive turned out to be somewhat more complicated than hoped.

We definitely hope that the bunnies can get a working Hawk together, as working 1970s HDDs like these are become pretty rare.

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Cat Feeder Depends On RFID To Keep The Peace At Dinnertime

February 28, 2023 by 10 Comments

Anyone with more than one cat can tell you that the joy mischief they bring into your life is much more than twice that of a single cat. And if those felines have different dietary needs, you can end up where [Benjamin Krejci] found himself, which resulted in this fancy RFID cat feeder.

For a little backstory, [Ben]’s furry friends [Luna] and [Fermi] have vastly different eating styles, with the former being a grazer and the latter more of a “disordered eater,” to put it politely. [Fermi] tends to eat until she vomits, which is fun, and muscles her pickier sister away from the bowl if there’s anything left in it. [Ben]’s idea was to leverage [Luna]’s existing RFID chip, which he figured would be a breeze. But the vet-inserted chip is designed to be read by a high-power reader directly in contact with the cat’s skin, which made reliably reading the chip a challenge.

Several round of design iteration resulted in the current configuration, with a large antenna coil poised above and behind the food dispenser. [Luna] has no choice but to put the back of her neck and shoulder blades almost directly in contact with the coil, which makes it easier to read the 134.2-kHz chip with a long-distance RFID module. If [Luna]’s chip is found, the lid on the food bowl opens gently and quietly, so as not to spook the mild-mannered cat. The lid stays open as long as [Luna] is in place thanks to some IR sensors, but as soon as she backs out, the lid comes down to keep [Fermi] from gorging herself.

Hats off to [Ben] for working through the problem and coming up with what looks like a fine solution. We suppose he could have tried something easier like weighing the two cats to distinguish between them, but this seems like a cleaner solution to us.

When One Cylinder Isn’t Enough: The Briggs And Stratton V8

February 28, 2023 by 13 Comments

The Briggs & Stratton single cylinder sidevalve engine is one that has been in production in one form or another for over a century, and which remains one of the simplest, most reliable, and easiest to maintain internal combustion engines there is. The little single-cylinder can be found on lawnmowers and other similar machinery everywhere, so it’s rather easy to find yourself in possession of more than one. [Lyckebo Mekaniska] evidently had no shortage of them, because he’s produced a V8 engine for a small lawn tractor using eight of them. A small air-cooled V8 sidevalve is something of a unique engine to be made in the 2020s, and the series of videos is definitely worth a watch from start to finish. We’ve been keeping an eye on this build for a while now, and we’ve embedded it below the break for your entertainment.

A CAD view of the V8 engine
Clearly a lot of CAD work has gone into this build.

For an engine which uses mass-produced engines for its construction, this one still relies heavily on parts machined from first principles. The cylinder blocks, valves, pistons, and crank rods are Briggs & Stratton, the rest is made in the workshop. It’s a design with the valves on the outside — so instead of the single camshaft you might expect from experience with OHV engines nestling in the V above the camshaft it has two camshafts at the bottom of the crankcase.

The crankcase is cast in sections first, followed by the machining of the crankshaft and camshafts, then the preparation of the cylinders.. The engine is assembled with a home made alternator on its flywheel and a conventional distributor from a donor vehicle. The lubrication system is another work of the machinist’s art, and the simple straight-through exhaust system is more at home on a drag racer than a lawnmower. Finally we see it running, and it sounds the business. Most recently he’s had to deal with a seizure and a replacement cylinder, but now it’s back together and he’s working on an improved cooling system.

All in all this is one heck of a build, and we wish we had some of those skills. We’re not sure whether he’ll mow the lawn with this thing, but one thing’s for sure, lawnmower hacking has quite a past.

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