Tiny pomodoro timer starts as soon as you plug it in.

Cherry Pomodoro Timer Forces You To Follow

October 31, 2021 by Kristina Panos 13 Comments

If you have trouble staying focused and getting work done, the Pomodoro Technique of working in 25-minute intervals with 5-minute breaks is pretty hard to beat. The only problem is that it requires a lot of input from the user, and all that timer-setting can get in the way of actually getting down to business. The absolute worst is when you find yourself working hard, but see that forgot to set the damn timer (ask us how we know). In essence, the tomato itself can only do so much — you have to actually use it and honor the timer, put in the work, and believe in the system.

But what if you didn’t have to do as much? With [Erfan Sn]’s design, all you have to do is plug it in to a USB port and the countdown starts automatically. Not only does this Pomodoro timer force you to get with the program, it also makes you take breaks from the screen by putting the computer into sleep mode when the 25 minutes (or whatever time you set in the software) are up. This thing even keeps track of your Pomodoro count.

At the heart of this build is the Digispark ATtiny85 dev board, which has a handy onboard USB plug. It can be built with or without the OLED screen, which is good if you are easily distracted by the timer itself. This cherry tomato only costs about $10 to make, it’s tiny, and you can take it anywhere.

As you will see in the gifs on GitHub, [Erfan Sn] has it plugged into a female USB-A to male USB-C, which is probably better for the computer long-term, what with all the plugging and unplugging. When we make ours, we’ll probably plug it into a hub that has power switches for each port.

If all of this sounds like too much work, check out this build that senses whether or not you’re in the chair.

Building A Kinetic Sand Art Table

October 31, 2021 by Lewin Day 16 Comments

Many of us have marveled at art installations that feature marbles quietly and ceaselessly tracing out beautiful patterns in sand. [DIY Machines] is here to show us that it’s entirely possible to build one yourself at home!

The basic mechanism is simple enough. The table uses a Cartesian motion platform to move a magnet underneath a table. On top of the table, a metal sphere attached to the magnet moves through craft sand to draw attractive patterns. An Arduino and Raspberry Pi work together to command the stepper motors to create various patterns in the sand.

Low-cost pine is used to build most of the table, with oak used for the attractive bare wooden top. RGB LEDs surround the sand surface in order to light the scene, with options for mad disco lighting or simple white light for a subtler look. Other nice touches include sitting the craft sand atop a layer of faux leather, so the ball moving through the sand doesn’t make annoying crunching sounds as the ball moves.

It’s a great build that focuses on the smaller details like noise that can make a big difference to the final experience. We’ve seen similar projects before, too. Video after the break.
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Hackaday Links: October 31, 2021

October 31, 2021 by Dan Maloney 17 Comments

Global supply chain issues are beginning to hit closer to home for the hacker community, as Raspberry Pi has announced their first-ever price increase on their flagship Pi 4. The move essentially undoes the price drop on the 2GB version of the Pi 4 that was announced in February, and sets the price back up from $35 to $45. Also rolled back is the discontinuation of the 1GB version, which will now be available at the $35 price point. The announcements come from Eben Upton himself, who insists the price increase is only temporary. We applaud his optimism, but take it with a grain of salt since he also said that 2021 production across the board will stay at the seven million-unit level, which is what they produced in 2020. That seems to speak to deeper issues within the supply chain, but more immediately, it’s likely that the supply of Pi products will be pinched enough that you’ll end up paying above sticker price just to get the boards you need. Hope everyone is stocked up.

On the topic of supply chain issues and their threat to Christmas gift-giving, here’s one product we hope is stranded in a container off Long Beach or better still, bobbing along in the Strait of Juan De Fuca: a toddler’s toy telephone that actually makes and receives calls. Anyone born in the last 60 years probably had one of the Fisher-Price Chatter telephone, a toy that in its original form looked like a desk telephone on wheels that was dragged behind the child, popping along and providing endless hours of clicky amusement as kids twisted the dial and lifted the receiver. Come to think of it, the Chatter telephone may be as close to a dial phone as anyone born since 1990 may have come. Anyway, some genius stuck a Bluetooth module into the classic phone to let it hook up to an app on an actual phone, allowing kids (or more likely their nostalgia-soaked parents) to make and receive calls. It’s actually priced at a reasonable $60, so there might be some hacking potential here.

Also tangential to supply chains, we stumbled across a video guide to buying steel that might interest readers. Anyone who has seen the displays of steel and other metals at the usual big-box retailers might wonder what the fuss is, but buying steel that way or ordering online is a great way to bust a project’s budget. Fabricator and artist Doug Boyd insists that finding a local steel supplier is the best bang for your buck, and has a bunch of helpful tips for not sounding like a casual when you’re ordering. It’s all good advice, and would have helped us from looking foolish a time or two at the metal yard; just knowing that pipe is measured by inside diameter while tubing is measured by outside dimensions is worth the price of admission alone.

With all the money you save on steel and by not buying Raspberry Pis, perhaps you’ll have a couple of hundred thousand Euros lying around to bid on this authentic 1957 Sputnik I satellite. The full-scale model of Earth’s first artificial satellite — manhole covers excluded — was a non-flown test article, but externally faithful to the flown hardware that kicked off the first Space Race. The prospectus says that it has a transmitter and a “modern power supply”; it’s not clear if the transmitter was originally part of the test article or added later. The opening bid is €85,000 and is expected to climb considerably.

And finally, there’s something fascinating about “spy radios,” especially those from the Cold War era and before, when being caught with one in your possession was probably going to turn out to be a very bad day. One such radio is the Radio Orange “Acorn” receiver, which is in the collection of the Crypto Museum. The radio was used by the Dutch government to transmit news and information into the occupied Netherlands from their exile in London. Built to pass for a jewelry box, the case for the radio was made from an old cigar box and is a marvel of 1940s miniaturization. The radio used three acorn-style vacuum tubes and was powered by mains current; another version of the Radio Orange receiver was powered by a bike dynamo or even a water-powered turbine, which could be run from a tap or garden hose. The video below shows the water-powered version in action, but the racket it made must have been problematic for its users, especially given the stakes.

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Extracting Data From Smart Scale Gives Rube Goldberg A Run For His Money

October 31, 2021 by Donald Papp 20 Comments

[Kevin Norman] got himself a smart body scale with the intention of logging data for his own analysis, but discovered that extracting data from the device was anything but easy. It turns out that the only way to access data from his scale is by viewing it in a mobile app. Screen-scraping is a time-honored method of pulling data from uncooperative systems, so [Kevin] committed to regularly taking a full-height screenshot from the app and using optical character recognition (OCR) to get the numbers, but making that work was a surprisingly long process full of dead ends.

First of all, while OCR can be reliable, it needs the right conditions. One thing that ended up being a big problem was the way the app appends units (kg, %) after the numbers. Not only are they tucked in very close, but they’re about half the height of the numbers themselves. It turns out that mixing and matching character height, in addition to snugging them up against one another, is something tailor-made to give OCR reliability problems.

The solution for this particular issue came from an unexpected angle. [Kevin] was using an open-source OCR program called Tesseract, and joined an IRC community #tesseract to ask for advice after exhausting his own options. The bemused members of the online community informed [Kevin] that they had nothing to do with OCR; #tesseract was actually a community for an open-source 3D FPS shooter of the same name. But as luck would have it, one of the members actually had OCR experience and suggested the winning approach: pre-process the image with OpenCV, using cv2.findContours() to detect and create a bounding box around each element. If an element is taller than a decimal point but shorter than everything else, throw it out. With that done, there were still a few more tweaks required, but the finish line was finally in sight.

Now [Kevin] can use the scale in the morning, take a screenshot, and in less than half a minute the results are imported into a database and visualizations generated. The resulting workflow might look like something Rube Goldberg would approve of, but it works!

Raspberry Pi Reads What It Sees, Delights Children

October 31, 2021 by Donald Papp 13 Comments

[Geyes30]’s Raspberry Pi project does one thing: it finds arbitrary text in the camera’s view and reads it out loud. Does it do so flawlessly? Not really. Was it at least effortless to put together? Also no, but it does wonderfully illustrate the process of gluing together different bits of functionality to make something new. Also, [geyes30]’s kids find it fascinating, and that’s a win all on its own.

The device is made from a Raspberry Pi and camera and works by sending a still image from the camera to an optical character recognition (OCR) program, which converts any visible text in the image to its ASCII representation. The recognized text is then piped to the espeak engine and spoken aloud. Getting all the tools to play nicely took a bit of work, but [geyes30] documented everything so well that even a novice should be able to get the project up and running in an afternoon.

Sometimes a function like text-to-speech is an end result in and of itself. This was also true of another similar project: Magic Mirror, whose purpose was to tirelessly indulge children’s curiosity about language.

Seeing other projects come to life and learning about new tools is a great way to get new ideas, and documenting them helps cross-pollinate among creative types. Did something inspire you recently, or have you documented your own project? We want to hear about it and so do others, so let us know via the tips line!

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A Builders Guide For The Perfect Solid-State Tesla Coil

October 31, 2021 by Dave Rowntree 13 Comments

[Zach Armstrong] presents for your viewing pleasure a simple guide to building a solid-state Tesla coil. The design is based around a self-resonant setup using the UCC2742x gate driver IC, which is used in a transformer-coupled full-wave configuration for delivering maximum power from the line input. The self-resonant bit is implemented by using a small antenna nearby the coil to pick up the EM field, and by suitably clamping and squaring it up, it is fed back into the gate driver to close the feedback loop. Such a setup within reason allows the circuit to oscillate with a wide range of Tesla coil designs, and track any small changes, minimizing the need for fiddly manual tuning that is the usual path you follow building these things.

Since the primary is driven with IGBTs, bigger is better. If the coil is too small, the resonant frequency would surpass the recommended 400 kHz, which could damage the IGBTs since they can’t switch much faster with the relatively large currents needed. An important part of designing Tesla coil driver circuits is matching the primary coil to the driver. You could do worse than checkout JavaTC to help with the calculations, as this is an area of the design where mistakes often result in destructive failure. The secondary coil design is simpler, where a little experimentation is needed to get the appropriate degree of coil coupling. Too much coupling is unhelpful, as you’ll just get breakdown between the two sides. Too little coupling and efficiency is compromised. This is why you often see a Tesla coil with a sizeable gap between the primary and secondary coils. There is a science to this magic!

A 555 timer wired to produce adjustable pulses feeds into the driver enable to allow easily changing the discharge properties. This enables it to produce discharges that look a bit like a Van De Graaff discharge at one extreme, and produce some lovely plasma ‘fire’ at the other.

We’ve covered Tesla coils from many angles over the years, recently this plasma tweeter made sweet sounds, and somehow we missed an insanely dangerous Tesla build by [StyroPyro] just checkout that rotary spark gap – from a distance.

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Dante’s Inferno Arcade Reveals Your True Fate

October 31, 2021 by Lewin Day 6 Comments

Many of us are vaguely familiar with the levels of hell described in Dante’s epic poem from the 14th century, even if we’ve never visited ourselves. It’s natural to wonder in which circle of hell one might end up, but that’s a question that [scubabear’s] arcade build seeks to answer.

The stand-up cabinet was built for The Magic Castle, Hollywood’s exclusive private club for the magic set. The design is loosely inspired by old-fashioned love testers, the sort of which you might have seen in that Simpsons episode. The club has traditionally issued members with unique RFID tags in keychains, which can be used to trigger special objects in the facility. In this case, when a member scans their keychain and places their hand on a handprint, the machine starts up.

The hand is detected by an Adafruit touch sensor board, and the machine begins determining the fate of the member while playing a short musical interlude. Once calculated by the Raspberry Pi within, the user’s name is read out based on the RFID data, and their destiny is read aloud. They’re then given a receipt stating their destination in hell, along with a quote from Dante’s Inferno.

It’s a fun game and one that we’d love to try out if we find ourselves visiting The Magic Castle one spooky day. It’s made all the better by the sheer quality of the cabinet and the associated illustrations from [Jeremy Owen.]

For those keen to do something similar, [scubabear] hasn’t skimped on the details of the construction nor the electronics that make it all work. We’ve seen other great builds too, from the carefully crafted to the glowiest you’ve ever seen. Video after the break.

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