3D Printed Key-Code Is Plastic Digital Logic

3D printers are great for creating static objects, but if you’re clever, it’s possible to print functional devices. If you’re absolutely brilliant you can go far beyond that, which is the case here. This door handle with a key-code lock does it all with 3D printing using mechanism designs that look like alien technology. This is just one application of a much more interesting mechanical digital logic they’re developing (PDF).

Working from the [Hasso-Plattner-Institut], the research team is focusing on metamaterials as mechanisms in and of themselves. The crux of this lock is a series of bistable springs that — if the correct code is entered — will trigger in series to unlock the door. The project builds on the grid of shearing cells seen in the door handle we featured last year. It happens quickly in the video, but the intricate cascade of the handle unlocking is a treat to witness.

It’s a fascinating show of mechanical design. The common elements of digital electronics are all present: set or unset bits, logic gates, propagation issues, the whole works. But there are added challenges in this system, like the need for special cells that can turn the logic chain by 90 degrees and split the signal into more than one part.

This signal splitting is seen in the upper right (bifurcation) and leads into what is in effect an amplifier. The locking bolt must be moved twice the distance of a normal cell, so a dual-cell input is necessary to offset the loss of force from the incoming smaller cells. Cognitively we understand this, but we’re still trying to gain an intuitive sense of the amplifer mechanism.

One thing’s for sure, the overall concept is far cooler than this admittedly awesome door lock mechanism. The paper is worth your time for a deep dive. It mentions their design editor software. You can play with it online but we don’t think it’s been updated to include the new logic cells yet.

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Build Your Own In-Fridge Soda Fountain

Who doesn’t love an ice cold soda? Lots of people, probably. This one’s not for them. It’s for those of us that are tired of having to go through the arduous process of manually opening a bottle and pouring a drink. Wouldn’t it be cool if you could have your own soda fountain at home? [Kedar Nimbalkar] thought so, and built a soda fountain that you can install right inside a fridge.

The system is based around using small pumps marketed as “6V DC air pumps” on Amazon. [Kedar] uses an indirect method of pumping the soda in this project. It’s a sad fact that it’s hard to find a cheap pump that’s safe to use with fluids for human consumption, and on top of that, many types of pump out there aren’t self-priming. This means the pump needs to be charged with fluid to work, which can make changing empty bottles a real pain.

Instead of pumping the fluid directly, the pumps instead push air into the top of the sealed soda bottles, which forces soda out of another tube in the bottle. This means that the pumps themselves don’t have direct contact with the soda which is a great design when working with stuff you’re going to put in your body. Following on from this careful design, the tubing selected is food safe. Unfortunately, even though the pumps don’t directly touch the soda itself, it’s highly unlikely the pumps chosen (designed for aquariums) are genuinely food-safe themselves.

When you’re building a beer funnel setup for Australia Day/4th of July/Other, using all manner of industrial or agricultural fittings may be a relatively low risk, as it’s a one-off exposure. But if you’re building a system handling products for human ingestion that you’re using on a regular basis, you really do want to make sure that the parts you use aren’t slowly poisoning you. There’s many ways this can happen — parts may corrode or react with substances in the food, plastics may outgas, or there may be lubricants in the parts that have toxic compounds in them. Just look what can happen if you drink wine out of a gun barrel — and that was from a single exposure!

Overall it’s a cool project, and one that would be especially fun and educational to do with children. Young humans are well known for their predilection towards sugary beverages, and have minds ready to be filled with knowledge about pumps, safe food handling practices, and of course, electronics. We also like [Kedar]’s use of commonly available materials, like a plastic food container for the enclosure. The project would be a great starter on your way to building a more complicated cocktail-mixing barbot. Video after the break.

We know peristaltic pumps are the go-to for safe liquid pumping. Anyone know a hacker friendly way of pumping air while ensuring all parts of the system are food safe? The most creative solution we’ve seen is to use breast pumps but it wasn’t ideal. Let us know your own tricks in the comments!

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A Walk-In Broadcast Transmitter

[Mr. Carlson] likes electronics gear. Mostly old gear. The grayer the case, the greener the phosphors, and the more hammertone, the better. That’s why we’re not surprised to see him with a mammoth AM radio station transmitter in his shop. That it’s a transmitter that you can walk into while it’s energized was a bit of a surprise, though.

As radio station transmitters go, [Mr. Carlson]’s Gates BC-250-GY broadcast transmitter is actually pretty small, especially for 1940s-vintage gear. It has a 250 watt output and was used as a nighttime transmitter; AM stations are typically required to operate at reduced power when the ionosphere is favorable for skip on the medium frequency bands. Stations often use separate day and night transmitters rather than just dialing back the daytime flamethrower; this allows plenty of time for maintenance with no interruptions to programming.

If you enjoy old broadcast gear, the tour of this transmitter, which has been rebuilt for use in the ham bands, will be a real treat. Feast your eyes on those lovely old bakelite knobs and the Simpson and Westinghouse meters, and picture a broadcast engineer in white short sleeves and skinny tie making notations on a clipboard. The transmitter is just as lovely on the inside — once the plate power supply is shut down, of course, lest [Mr. Carlson] quickly become [the former late Mr. Carlson] upon stepping inside. Honestly, there aren’t that many components inside, but what’s there is big – huge transformer, giant potato slicer variable caps, wirewound resistors the size of paper towel tubes, and five enormous, glowing vacuum tubes.

It’s a pretty neat bit of broadcasting history, and it’s a treat to see it so lovingly restored. [Mr. Carlson] teases us with other, yet larger daytime transmitters he has yet to restore, and we can’t wait for that tour. Until then, perhaps we can just review [Mr. Crosley]’s giant Cincinnati transmitter from the 1920s and wait patiently.

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Flux Capacitor Prop With Christopher Lloyd’s Stamp Of Approval

We love our props here at Hackaday, and whenever we come across a piece from the Back To The Future fandom, it’s hard to resist showcasing it. In this case, [Xyster101] is showing of his build of Doc Brown’s Flux Capacitor.

[Xyster101] opted for a plywood case — much more economical than the $125 it would have cost him for a proper electrical box. Inside, there’s some clever workarounds to make this look as close as possible to the original. Acrylic rods and spheres were shaped and glued together to replicate the trinity of glass tubes, 3/4″ plywood cut by a hole saw mimicked the solenoids, steel rods were sanded down for the trio of points in the centre of the device and the spark plug wires and banana connectors aren’t functional, but complete the look. Including paint, soldering and copious use of hot glue to hold everything in place, the build phase took about thirty hours.

The LEDs have multiple modes, controlled by DIP switches hidden under a pipe on the side of the box. There’s also motion sensor on the bottom of the case that triggers the LEDs to flicker when you walk by. And, if you want to take your time-travel to-go, there’s a nine volt plug to let you show it off wherever — or whenever — you’re traveling to. Check out the build video after the break.

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VCF: Popular Electronics And Southwest Technical Products Corporation

Hackaday owes a lot to the hobbyist electronics magazines of yesteryear. Back in the day, Popular Electronics and Radio-Electronics would publish projects and articles about DIY electronics – more or less the same editorial purview we hold today. Some of these projects would become full-fledged products, and you need only look at the Altair for what can happen at this confluence of publishing and engineering.

One of the more popular companies to come out of these hobbyist trade magazines was SWTPC, or Southwest Technical Products Corporation. This was the company that brought one of the first microcomputers to the masses with the SWTPC 6800. This wasn’t just a homebrew microcomputer company – there were Nixie clocks, test gear, and stereo preamplifiers – all things that could easily find a place on the pages of Hackaday today.

This year at the Vintage Computer Festival East, [Michael Holley] brought out the test gear he’s been collecting for the past few decades. These are machines that wouldn’t be out of place on any DIY electronics blog today. This is by all accounts the pre-history of the maker movement.

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IOT Startup Bricks Customers Garage Door Intentionally

Internet of Things startup Garadget remotely bricked an unhappy customer’s WiFi garage door for giving a bad Amazon review and being rude to company reps. Garadget device owner [Robert Martin] found out the hard way how quickly the device can turn a door into a wall. After leaving a negative Amazon review, and starting a thread on Garadget’s support forum complaining the device didn’t work with his iPhone, Martin was banned from the forum until December 27, 2019 for his choice of words and was told his comments and bad Amazon review had convinced Garadget staff to ban his device from their servers.

The response was not what you would expect a community-funded startup. “Technically there is no bricking, though,” the rep replied. “No changes are made to the hardware or the firmware of the device, just denied use of company servers.” Tell that to [Robert] who can’t get into his garage.

This caused some discontent amoung other customers wondering if it was just a matter of time before more paying customers are subjected to this outlandish treatment. The Register asked Garadget’s founder [Denis Grisak] about the situation, his response is quoted below.

 It was a Bad PR Move, Martin has now had his server connection restored, and the IOT upstart has posted a public statement on the matter.– Garadget

This whole debacle brings us to the conclusion that the IoT boom has a lot of issues ahead that need to be straightened out especially when it comes to ethics and security. It’s bad enough to have to deal with the vagaries of IoT Security and companies who shut down their products because they’re just not making enough money. Now we have to worry about using “cloud” services because the people who own the little fluffy computers could just be jerks.

Hackaday Prize Entry: Modular Instrumentation For Aircraft

Parts, tools, and components for aviation and aerospace are sold in ‘Aviation Monetary Units’ (AMU). Right now, the conversion factor from USD to AMU is about 1000 to 1. This stuff is expensive, but there is a small portion of the flying community that prides itself on not breaking the bank every time something needs to be replaced. Theses are often the microlight, ultralight, and experimental aircraft enthusiasts. Steam gauges are becoming obsolete and expensive to repair, and you’re not going to throw a 15 AMU Garmin G500 in an ultralight that only costs 10 AMU.

To solve this problem, [Rene] is turning to sensors, displays, and microcontrollers that are cheap and readily available to build modular aviation instruments.

As with all aviation gear, the first question that springs to mind is, ‘what will the FAA think about this?’. [Rene] is in South Africa, so the answer is, ‘nothing’. If a few American pilots decide to build one of these, that’ll fly too; these are instruments designed for non-type-certified aircraft. That’s not to say there are no rules for what goes into these aircraft, but the paperwork is much easier.

Right now, the design goals for [Rene]’s instruments is under 0.1 AMU per module, robust, RF shielded, with engine monitoring, fuel management, heading, air and ground speed, altitude, attitude, and all the other gauges that make flying easy. He’s using a CAN bus for all of these modules, and in the process slowly dragging the state of the art of ultralight aviation into the 1990s. It’s fantastic work, and we can’t wait to see some of these modules in the air.