A Baseball Cap That Films The Past

July 21, 2019 by Lewin Day 17 Comments

The vast majority of cameras will start recording at the press of a button. This is perfectly acceptable behaviour if you wish to film something that hasn’t happened yet. If you want to film something that’s already over, you’re out of luck. [Johan Link] has built a camera designed to do just that, however, and put it on a cap.

The project consists of a Raspberry Pi 3B, combined with a 1080p USB webcam and a 5000 mAh power bank. These are attached to a baseball cap in order to shoot footage from the point of view of the wearer. The camera records continuously, saving the last 7 seconds of recorded video when the button is pressed — perfect for capturing things just after they’ve happened.

It’s a rolling record feature similar to that included with many dashcams and action cameras. Software is available on Github for those interested. While [Johan] has chosen a New York Yankees hat as the basis for the build, we’re confident it should work similarly well with your Seattle Seahawks cap. Raiders fans should contact the garment manufacturer.

An Epic Tale Of Thermistors: Tricks For Much Better Temperature Sensing

July 21, 2019 by Kerry Scharfglass 25 Comments

For years [Edward] has been building professional grade underwater sensing nodes at prices approachable for an interested individual without a government grant. An important component of these is temperature, and he has been on a quest to get the highest accuracy temperature readings from whatever parts hit that sweet optimum between cost and complexity. First there were traditional temperature sensor ICs, but after deploying numerous nodes [Edward] was running into the limit of their accuracy. Could he use clever code and circuitry to get better results? The short answer is yes, but the long answer is a many part series of posts starting in 2016 detailing [Edward]’s exploration to get there.

The first step is a thermistor, a conceptually simple device: resistance varies with temperature (seriously, how much more simple can a sensor get?). You can measure them by tapping the center of a voltage divider the same way you’d measure any other resistance, but [Edward] had discarded this idea because the naive approach combined with his Arduino’s 10 bit ADC yielded resolution too poor to be worthwhile for his needs. But by using the right analog reference voltage and adjusting the voltage divider he could get a 20x improvement in resolution, down to 0.05°C in the relevant temperature range. This and more is the subject of the first post.

What comes next? Oversampling. Apparently fueled by a project featured on Hackaday back in 2015 [Edward] embarked on a journey to applying it to his thermistor problem. To quote [Edward] directly, to get “n extra bits of resolution, you need to read the ADC four to the power of n times”. Three bits gives about an order of magnitude better resolution. This effectively lets you resolve signals smaller than a single sample but only if there is some jitter in the signal you’re measuring. Reading the same analog line with no perturbation gives no benefit. The rest of the post deals with the process of artificially perturbing the signal, which turns out to be significantly complex, but the result is roughly 16 bit accuracy from a 10 bit ADC!

What’s the upside? High quality sensor readings from a few passives and a cheap Arduino. If that’s your jam check out this excellent series when designing your next sensing project!

External Buffer Boosts 3D Printer Filament Splicing On The Palette 2

July 21, 2019 by Tom Nardi 15 Comments

There was a time when most of us thought the next logical step for desktop 3D printing was to add additional extruders and hotends, allowing the machine to print in multiple colors or materials. Unfortunately such arrangements quickly become ungainly, and even with just two extruders, calibration can be a nightmare. Because of this, development has been trending towards systems that use just one hotend and simply alternate the filament being fed into it. But such systems have their own problems.

Arguably the biggest issue is how long it takes to switch filaments. The Palette 2 uses a physical buffer of spliced filament to try and keep ahead of the printer, but as [Kurt Skauen] demonstrates, there are considerable performance gains to be had by building a bigger buffer. He says there’s still some calibration issues to contend with, but judging by the video after the break, we’d say he is certainly on the right track.

The buffer is necessary to give the spliced filament time to cool and bond before being fed into the printer, but as currently designed, the machine simply can’t store enough of it to keep up with high print speeds. The stock buffer area holds 125mm worth of spliced filament, but the modification [Kurt] has designed adds a whopping 280mm on top of that to reach more than three times the stock capacity.

He’s successfully tested printing at speeds as high as 200mm/s with his upgraded buffer, a big improvement over what he was seeing with the original buffer area. This despite the fact that Mosaic (the company that produces the Palette) claim the original buffer size was already more than sufficient. It seems we’ve found ourselves in the middle of a debate between Mosaic and some very vocal members of the community, and while we don’t want to take sides, it’s hard to ignore [Kurt]’s findings.

Want to make your own? [Kurt] has released all the information necessary for others to duplicate his work, including the STLs for all printed parts and a list of the bearings, springs, and fasteners you’ll need to put it together. It looks like a fairly large undertaking, but with the potential for such a considerable speed boost, we don’t doubt others will be willing to take the plunge. One person who printed and assembled an earlier version of the buffer upgrade reports their print speeds with a 0.8 mm nozzle have more than doubled.

The Palette has come a long way from we first saw it in 2016, and since then, Prusa has thrown their orange hat into the ring with their own filament-switching upgrade. Neither machine is without its niggling issues, but they’re still probably our best shot at taking desktop 3D printing to the next level.

Continue reading “External Buffer Boosts 3D Printer Filament Splicing On The Palette 2” →

A New Motherboard For Amiga, The Platform That Refuses To Die

July 21, 2019 by Jenny List 34 Comments

If you go out and buy a computer right now, how many choices do you really have? Generally speaking, there’s PC or Mac. If we were being generous you could consider Chromebook and perhaps even mobile, but let’s be honest, computing is a two-party system with the ability to dump the OS and run Linux as the obvious third-party disruptor. It wasn’t always like this.

In the early years of personal computing there were a slew of serious contenders. A PC, a Mac, an Atari ST, an Amiga, and several more that all demanded serious consideration on the general purpose desktop computer market. Of all these platforms, the Amiga somehow stubbornly refuses to die. The Amiga 1200+ from [Jeroen Vandezande] is the latest in a long procession of post-Commodore Amigas, and as its name suggests it provides an upgrade for the popular early-1990s all-in-one Amiga model.

It takes the form of a well-executed open-source PCB that’s a drop-in replacement for the original A1200 motherboard. CPU, RAM, and video are broken out onto daughterboards, with PCMCIA replaced by an SD card slot. The catch: it does require all the custom Amiga chips from a donor board.

The original Amiga 1200 was a significant upgrade to the architecture of the 1980s originals, and this certainly provides a much-needed enhancement to its underwhelming 68EC020 processor. It’s fair to say that this is the Amiga upgrade we’d all have loved to see in about 1996 rather than waiting until 2019. It’s still a delight for a retrogaming enthusiast; many of those who keep it alive remember the Amiga was the best multimedia platform that could be had for a few glorious years.

We’ve brought you a host of Amiga projects over the years, including the resurrection of an A500 and of course another A1200 PCB.

Thanks to [Eric Hill] for the tip.

DIY Industrial Oven Brings The Heat

July 21, 2019 by Kristina Panos 4 Comments

When [Turbo Conquering Mega Eagle] tried lost wax casting, he ended up with a fireball and a galvanizing sense of disappointment. There wasn’t enough heat to get all the wax out, and the paraffin ignited. Though a bit burned by the experience, it didn’t extinguish his desire to do lost wax casting. In a textbook case of project-spawns-project, this eagle decided to wing it and made his own high-temperature oven.

This is true, seat-of-your-pants DIY. For this project, [TCME] treated himself to a virgin sheet of mild steel, a metallic delicacy for a guy who seems used to using whatever is available. The oven consists of a welded-together box inside a larger box, with insulation between the two. The door is a shallower box filled with insulation, with hinges on the right and a sturdy-looking gravity catch on the left. [TCME] welded together a nice little box for the 12-volt, 1000 °C temp controller module, and tacked some tabs to the outside to help wrangle the wires. Lower your visor and click past the break to watch this hot box come together.

We hope [TCME] answers the burning questions of how well the thing loses wax, and how fast it bakes a pizza. Meantime, here’s a clay oven that’s built to pizza.

Continue reading “DIY Industrial Oven Brings The Heat” →

Building A Bigger Cloud Chamber

July 20, 2019 by Lewin Day 11 Comments

Cloud chambers are an exciting and highly visual science experiment. They’re fascinating to watch as you can see the passage of subatomic particles from radioactive decay with your very own eyes. Many elect to build small chambers based on thermoelectric Peltier elements, but [Cloudylabs] decided to do something on a grander scale.

It’s a hefty chamber, and a very clean build.

[Cloudylabs] started building cloud chambers after first seeing one in a museum back in 2010. The first prototype was an air-cooled Peltier device, with a cooled area of just 4x4cm. Over the years, and after building many more Peltier-based chambers, it became apparent that the thermoelectric modules were somewhat less than robust, often failing after many thermal cycles. Wanting to take things up a notch, [Cloudylabs] elected to build a much larger unit based on phase-change technology, akin to the way a refrigerator works.

The final product is astounding, consisting of a 32x18cm actively cooled area mounted within a large glass viewing case. A magnet is mounted underneath which causes certain particles to curve in relation to the field, as well as an electrically charged grid up top. The chamber is capable of operating for up to 12 hours without requiring any user intervention.

Cloud chambers are always beautiful, and even moreso at this larger scale. When radioactive materials are introduced into the chamber the trails generated are long and easily visible. It’s a daunting build however, and the final product weighs over 30 kilograms. You might want to start with something a little smaller for your first build. Video after the break.

Continue reading “Building A Bigger Cloud Chamber” →

Project Perceives Pondering, Prints Poetry

July 20, 2019 by Daniel Bogdanoff 5 Comments

If poetry is your thing, this hack might convince you that your brain is more advanced than the rest of us poor sots. [Roni Brandini] designed a system that prints lines of poetry when you concentrate. The Mind Poetry project uses an EEG headset from Mattel’s Mindflex toy and pipes your brain’s signals to an Arduino Mega 2560. The system then looks for patterns of brain waves that indicate concentration. As you maintain your concentration, the system continues to print lines of poetry to a small display.

[Roni] follows the standard Mindflex hack process by tapping into the data transmission pin on the Mindflex board. Optoisolation is provided by a PC817 to make sure wall power can’t accidentally bleed over into your own wetware. You could get away with just using batteries, but isolation is still a best practice.

The Arduino Brain Library is used to decipher the signal. The Mindflex picks up brain waves from roughly 1 Hz to 50 Hz, which is enough bandwidth to approximately determine mental state. For example, Theta waves are in the 4 Hz to 7 Hz range and can indicate a relaxed, meditative state. Low Beta waves range from 13 Hz to 17 Hz and indicate an alert, focused mental state. The Mindflex system is also generous in that it provides derived meditation and attention scores, ranging from 0 to 100.

It’s difficult to get a high level of precision with this sensor and sampling system, so the code uses [Roni]’s custom recipe of meditation score, attention score, and Low Beta value. He finds it most effective to trigger actions based on a relationship of these scores instead of focusing on the readings themselves. For example, an uptick in both Low Beta waves and the attention score indicate concentration.

If the wearer is concentrating, the system prints lines of poetry to the display and charts the three values. As an added gamification, it’ll tell you how many times you broke concentration before you completed the poem. One can imagine a game that tries to break concentration by printing other phrases or even activating an array of mechanical distractions.

If poetry isn’t your thing, you’re in luck. The “Mind Poetry” project also makes some headway (pun intended) with processing the EEG headset’s signals and triggering actions This means you don’t have to be into the poetry scene to reap the benefits. You now have the bones of a hack that lets you control things with your brain muscles and without your muscle muscles.

For inspiration, check out some other Mindflex hacks that let you order drinks with your mind (recommended), shock the heck out of people (not recommended), or even move around your skirt (uh… you do you?).

Continue reading “Project Perceives Pondering, Prints Poetry” →