Misc Hacks

4165 Articles

The Future Of Fritzing Is Murky At Best

February 14, 2019 by 69 Comments

Fritzing is a very nice Open Source design tool for PCBs, electrical sketches, and schematics for designers and artists to move from a prototype to real hardware. Over the years, we’ve seen fantastic projects built with Fritzing. Fritzing has been the subject of books, lectures, and educational courses, and the impact of Fritzing has been huge. Open up a book on electronics from O’Reilly, and you’ll probably see a schematic or drawing created in Fritzing.

However, and there’s always a however, Fritzing is in trouble. The project is giving every appearance of having died. You can’t register on the site, you can’t update parts, the official site lacks HTTPS, the Twitter account has been inactive for 1,200 days, there have been no blog posts for a year, and the last commit to GitHub was on March 13th. There are problems, but there is hope: [Patrick Franken], one of the developers of Fritzing and the president of the PCB firm Aisler which runs the Fritzing Fab, recently gave a talk at FOSDEM concerning the future of Fritzing. (That’s a direct FTP download, so have fun).

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Tritium Tesseract Makes A Nifty Nightlight

February 11, 2019 by 27 Comments

As the cube is to three dimensions, the tesseract is to four. Mortals in this universe find it difficult to contemplate four-dimensional geometry, but there are methods of making projections of such heretical shapes in our own limited world. [Sean Hodgins] was interested in the geometry, and decided to build a tesseract featuring everyone’s favourite isotope of hydrogen, tritium.

The build starts with a 3D printed inner and outer frame, sourced in this case from Shapeways in nylon. Both frames have holes which are designed as a friction fit for off-the-shelf tritium vials. These vials use the radioactive decay of tritium with a phosphor coating to create a dim glow which lasts approximately a decade. With the inner frame held inside the outer with the vials acting as structural supports, the inner and outer surfaces are then fitted with semi-transparent mirrored acrylic, creating a nice infinity effect.

It’s a fun trinket that would be perfect as a MacGuffin in any sci-fi film with a weak plot. [Sean] notes that while the tritium glow is disappointingly dim, the device does make a good nightlight. If you’ve built one and get bored with the hypercube, you can always repurpose your tritium vials into a nuclear battery. Video after the break.

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R/C Whirlygig Is Terrifyingly Unstable

February 6, 2019 by 10 Comments

In the days during and immediately after World War II, aerospace research was a forefront consideration for national security. All manner of wild designs were explored as nation states attempted to gain the upper hand in the struggle for survival. The Hiller Hornet was one such craft built during this time – a helicopter which drove the rotor through tip-mounted ramjets. Unsurprisingly, this configuration had plenty of drawbacks which prevented it from ever reaching full production. The team at [FliteTest] had a soft spot for the craft, however, and used it to inspire their latest radio controlled experiment.

Initial experiments consisted of a modified foam wing from a model seaplane, with two left wings facing opposite directions, and joined in the middle. Two motors and props were fitted to the wings to provide rotational motion. After some initial vibration issues were solved, the improvised craft generated barely enough lift to get off the ground. Other problems were faced with centripetal forces tearing the propellers off the wing due to the high rotational speeds involved.

A second attempt started from scratch, with a four wing setup being used, with much higher camber, with the intention to generate more lift with a more aggressive airfoil, allowing rotational speeds to be decreased. The craft was capable of getting off the ground, but instabilities likened to the pendulum rocket fallacy prevented any major gain in altitude.

We’d love to see a redesign to solve some of the issues and allow the craft to sail higher into the air. If you think you know the solution to the whirly bird’s dynamic problems, be sure to let us know in the comments. It should be possible, as we’ve seen successful designs inspired by maple seeds before. Video after the break.

[Thanks to Baldpower for the tip!]

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Hacking The Humble Roadster Bicycle

February 6, 2019 by 65 Comments

Think of bicycles, and your first mental image could be something pretty fancy. Depending on which side of the sport you favor, you could end up thinking of a road bike or an MTB, maybe DH, CX, BMX, TT, tandem or recumbent.

But for people in most parts of the World such as Asia, Africa and South America, the bicycle conjures up a very different image – that of the humble roadster. And this simple, hardy machine has spawned innumerable hacks to extend its usefulness and functionality by enterprising people with limited means. For them, it is not as much a means of transport, as a means for livelihood and survival.
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Sudo Find Me A Parking Space; Machine Learning Ends Circling The Block

February 4, 2019 by 29 Comments

If you live in a bustling city and have anyone over who drives, it can be difficult for them to find parking. Maybe you have an assigned space, but they’re resigned to circling the block with an eagle eye. With those friends in  mind, [Adam Geitgey] wrote a Python script that takes the video feed from a web cam and analyzes it frame by frame to figure out when a street parking space opens up. When the glorious moment arrives, he gets a text message via Twilio with a picture of the void.

It sounds complicated, but much of the work has already been done. Cars are a popular target for machine learning, so large data sets with cars already exist. [Adam] didn’t have to train a neural network, either–he found a pre-trained Mask R-CNN model with data for 80 common objects like people, animals, and cars.

The model gives a lot of useful info, including a bounding box for each car with pixel coordinates. Since the boxes overlap, there needs be a way to determine whether there’s really a car in the space, or just the bumpers of other cars. [Adam] used intersection over union to do this, which is conveniently available as a function of the Mask R-CNN model’s library. The function returns a score, so it was just a matter of ignoring low-scoring bounding boxes.

[Adam] purposely made the script adaptable. A few changes here and there, and you could be picking up tennis balls with a robotic collector or analyzing human migration patterns on your block in no time. Or change it up and detect all the cars that run the stop sign by your house.

Thanks for the tip, [foamyguy].

High-Style Ball Balancing Platform

February 2, 2019 by 14 Comments

If IKEA made ball-balancing PID robots, they’d probably look like this one.

This [Johan Link] build isn’t just about style. A look under the hood reveals not the standard, off-the-shelf microcontroller development board you might expect. Instead, [Johan] designed and built his own board with an ATmega32 to run the three servos that control the platform. The entire apparatus is made from a dozen or so 3D-printed parts that interlock to form the base, the platform, and the housing for the USB webcam that’s perched on an aluminum tube. From that vantage point, the camera’s images are analyzed with OpenCV and the center of the ball is located. A PID loop controls the three servos to center the ball on the platform, or razzle-dazzle it a little by moving the ball in a controlled circle. It’s quite a build, and the video below shows it in action.

We’ve seen a few balancing platforms before, but few with such style. This Stewart platform comes close, and this juggling platform gets extra points for closing the control loop with audio feedback. And for juggling, of course.

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Continuous Computing The Analog Way

January 29, 2019 by 43 Comments

When your only tool is a hammer, everything starts to look like a nail. That’s an old saying and perhaps somewhat obvious, but our tools do color our solutions and sometimes in very subtle ways. For example, using a computer causes our solutions to take a certain shape, especially related to numbers. A digital computer deals with numbers as integers and anything that isn’t is actually some representation with some limit. Sure, an IEEE floating point number has a wide range, but there’s still some discrete step between one and the next nearest that you can’t reduce. Even if you treat numbers as arbitrary text strings or fractions, the digital nature of computers will color your solution. But there are other ways to do computing, and they affect your outcome differently. That’s why [Bill Schweber’s] analog computation series caught our eye.

One great example of analog vs digital methods is reading an arbitrary analog quantity, say a voltage, a temperature, or a shaft position. In the digital domain, there’s some converter that has a certain number of bits. You can get that number of bits to something ridiculous, of course, but it isn’t easy. The fewer bits, the less you can understand the real-world quantity.

For example, you could consider a single comparator to be a one-bit analog to digital converter, but all you can tell then is if the number is above or below a certain value. A two-bit converter would let you break a 0-3V signal into 1V steps. But a cheap and simple potentiometer can divide a 0-3V signal into a virtually infinite number of smaller voltages. Sure there’s some physical limit to the pot, and we suppose at some level many physical values are quantized due to the physics, but those are infinitesimal compared to a dozen or so bits of a converter. On top of that, sampled signals are measured at discrete time points which changes certain things and leads to effects like aliasing, for example.

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