Finally, A Calculator For The Atomic Age!

In the 1950s, a nuclear-powered future seemed a certainty. The public had not been made aware of the dangers posed by radioactive material, any large-scale accidents involving nuclear reactors had either been hushed up or were yet to happen, and industry and governments were anxious to provide good PR to further their aims. Our parents and grandparents were thus promised a future involving free energy from nuclear reactors in all sorts of everyday situations.

With the benefit of hindsight, we of course know how the story turned out. Windscale, Three Mile Island, Chernobyl, and Fukushima, and we’re still waiting for our atomic automobiles.

If you have a hankering for nuclear-powered domestic appliances though, all is not lost. [GH] is leading the charge towards a future of atomic energy, with a nuclear-powered calculator. It’s not quite what was promised in the ’50s, but it is nevertheless a genuine appliance for the Atomic Age. At its heart is not a 1950s-style fission reactor though, but a tritium tube. Beta particles from the tritium’s decay excite a phosphor coating on the tube’s inside wall, producing a small amount of light. This light is harvested with a solar cell, and the resulting electrical energy is stored in an electrolytic capacitor. The cell has an open-circuit voltage of 1.8 V, and the 100 μF capacitor in question stores a relatively tiny 162 μJ. From this source, a dollar store calculator can operate for about 30 sec, so there should be no hanging about with your mathematics.

We’ve brought you a tritium battery before, albeit a slightly larger one. And should you need the comforting glow of a tritium tube but not the radiation risk, how about this LED-based substitute?

Improved Game Tokens with Laser Cutting and Clever Design

[Martin Raynsford] is a prolific project maker, especially when it comes to using a laser cutter. These laser-cut token counters for the board game Tigris & Euphrates demonstrate some clever design, and show that some simple touches can make a big difference.

In the digital version of the game, the tokens conveniently display a number representing their total power value. [Martin] liked this feature, and set out to design a replacement token for the tabletop version that could display a number while still keeping the aesthetic of the originals. The tokens were designed as a dial with a small cutout window to show a number, but the surface of the token showing color and icon is still mostly unchanged.

Magnets hold the top and bottom together, and because of the small size of the assembly, no detents are needed. Friction is enough to keep things from moving unintentionally. The second noteworthy design feature is the material for the top layer of the token. This layer is made from 0.8 mm birch plywood; a nice and thin top layer means a wider viewing angle because the number is nearer to the surface. If the top layer were thicker, the number would be recessed and harder to see.

[Martin] made the design file available should anyone wish to try it out. No stranger to games, he even once game-ified the laser itself, turning it into a physical version of Space Invaders. Be sure to check it out!


Anyone Need a Little Fuming Nitric Acid?

If there’s a chemical with a cooler name than “fuming nitric acid,” we can’t think of it. Nearly pure nitric acid is useful stuff, especially if you’re in the business of making rocket fuels and explosives. But the low-end nitric acid commonly available tops out at about 68% pure, so if you want the good stuff, you’ll have to synthesize fuming nitric acid yourself. (And by “good stuff”, we mean be very careful with the resulting product.)

Fuming nitric acid comes in two colors – red fuming nitric acid (RFNA), which is about 90% pure and has some dissolved nitrogen oxides, giving it its reddish-brown color. White fuming nitric acid (WFNA) is the good stuff — more than 99% pure. Either one is rough stuff to work with — you don’t want to wear latex or nitrile gloves while using it. It’s not clear what [BarsMonster] needs the WFNA for, although he does mention etching some ICs. The synthesis is pretty straightforward, if a bit dangerous. An excess of sulfuric acid is added to potassium nitrate, and more or less pure nitric acid is distilled away from the resulting potassium sulfate. Careful temperature control is important, and [BarsMonster] seems to have gotten a good yield despite running out of ice.

We don’t feature too many straight chemistry hacks around here, but this one seemed gnarly enough to be interesting. We did have a Hackaday Prize entry a while back on improvements to the Haber process for producing ammonia, which curiously is the feedstock for commercial nitric acid production processes.

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RADAR Controlled Speakers

[Scott] had a simple problem – he was tired of leaning over his work bench to change the volume on his speakers. He desired a system that would readily allow him to switch the speakers on and off from a more comfortable distance. Not one to settle for the more conventional solutions available, [Scott] whipped up a RADAR-activated switch for his speaker system.

The build relies on a surprisingly cost-effective RADAR module available off the shelf, running in the 5.8GHz spectrum. At under $10, it’s no big deal to throw one of these into a project that requires some basic distance sensing. [Scott] decided to keep things simple – instead of going with a full-fat microcontroller to control the speakers, a 74HC590 IC was used to create a latch. Each time the RADAR module senses an object in close proximity, it toggles the state of the latch. The latch then controls a transistor that switches the power for the speakers.

Overall it’s a build that combines a modern integrated RADAR module with some very simple control logic to create a functional build. Of course, there’s so much more you can do with some 74-series logic. Video after the break.

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Hackaday Prize Entry: Wireless Weather Station Protects Crops from Frost

It seems like you hear it every year — a late or early frost threatens some crop or another, forcing farmers to take drastic action to avoid financial ruin. But even when the weather cooperates on a large scale, microclimates can still cause big problems in small enough areas to go unnoticed until after the damage is done.

As always, better data can lead to better decisions, and increased granularity of environmental data could do wonders for certain kinds of agriculture. Enter SLoRa, a wireless weather station for agriculture. Aimed at providing a network of cheap, low-power temperature sensors, [Dorijan]’s proposed system would allow farmers to take active measures to protect their trees from frosts — smudge pots to heat the nascent fruit, sprinklers to apply a protective layer of ice, or even hovering helicopters to move massive amounts of warmer air into cold spots. With a solar powered sensor array and a LoRa link to a hilltop gateway, each SLoRa sensor deployed will be one more data point a farmer can use to determine where to deploy his or her limited resources.

Need to get up to speed on LoRa? You could do worse than learning how to listen in on LoRa signals with an SDR dongle.

Sort Out Chemical Storage For Your Shop

There is one constant in the world of hardware hacker’s workshops, be they a private workshop in your garage or a public hackspace, and it goes something like this:

Everybody’s a safety expert in whatever it is they are working with, right up until the accident.

In other words, it is very tempting to harbour a cavalier attitude to something that either you are familiar with or the hazards of which you do not understand, and this breeds an environment in which mishaps become a distinct possibility.

As hardware people, we are familiar with basic tool safety or electrical safety. The chances are that we’ve had it drummed into us at some time in our growing up, by a lab supervisor, a workshop teacher, or a parent. That you as readers and I as writer have survived this long is testament enough to the success of that education. But what about those areas in which we may not have received such an education, those things which we either encounter rarely or seem harmless enough that their safety needn’t be our concern? Chemicals, for example: everything from glue through solvents and soldering consumables to PCB chemicals and even paint. It all seems safe enough, what could possibly go wrong? The answer to that question is probably something most of us would prefer never to find out, so it’s worth looking in to how a well-run workshop can manage its chemicals in as safe a manner as possible.

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PCB Art Becomes Lapel Pins

We’re now living in the golden age of PCB art. Over the last year or so, the community has learned to manipulate silk screen, copper, and solder mask layers into amazing pieces of craftsmanship. These boards are putting the ‘A’ in STEAM, and now we have fiberglass replacements for enamel lapel pins.

[jglim] didn’t have much experience with fabric, but a PCB lapel pin was something that seemed like it should work. There are really only three parts to a lapel pin — the small ornamental pin itself, a solderable spike somehow attached to the pin (usually by soldering), and a clasp that holds the pin steadfastly to a lapel. The spike and clasp assembly were easily sourced on AliExpress, with one hundred clasps available for seven dollerydoos.  Attaching the spike to the PCB was as simple as adding a circular copper pad on the obverse side, applying some solder, and the liberal application of toaster ovens.

The design of the pin was based on the HTML5 logo, with the actual art done in Photoshop using a palette picked from OSHPark’s preview colors. The four colors used in this design are bare copper, a light purple for mask over copper, a darker purple for mask without copper, and a pale yellow for exposed FR4. This design was imported into KiCad with the Bitmap2Component tool.

The assembly of these lapel pins went very easily, and the finished product looks great. There’s a lot you can do with the standard OSHPark color stackup like making money of me, and this is a great example of exactly how much you can do with PCB art.