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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Make Your Own Phosphorescent Material

February 6, 2019 by 9 Comments

Phosphors are key to a whole swathe of display and lighting technologies. Cathode ray tubes, vacuum fluorsecent displays, and even some white LEDs all use phosphors to produce light. [Hydrogen Time] decided to make a green phosphorescent material, and has shared the process on Youtube, embedded below.

The aim is to produce zinc sulfide crystals doped with copper impurities. This creates a phosphor with a familiar green glow. [Hydrogen Time] starts by noting that it’s important to make sure all chemicals used are of good quality, as even slight impurities can spoil the final product.

Zinc sulfide is made into an aqueous solution, before a highly diluted copper sulfate solution is added, along with ammonium chloride to act as a flux. The mixture is stirred, before being heated in a tube flushed with argon. After firing, the phosphor is washed with water and allowed to cool.

The final product is demonstrated to glow a vibrant green under UV light, showing the process to be successful. [Hydrogen Time] intends to use the homebrew phosphor in future work to produce a display. It recalls us of [Jeri Ellsworth], producing her own EL wire at home. Video after the break.

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Make The Time To Fix Your Time Debt

February 6, 2019 by 23 Comments

You’re too busy to read more than this intro paragraph. We all are. Your interest might get piqued enough to skim, but you can’t read the full thing. Our lives all resemble the White Rabbit, constantly late for our next thing, never enjoying the current thing. You feel simultaneously super productive and yet never productive enough to be satisfied. You yearn for a Jarvis that can automate the mundane aspects of your projects, and yet the prospect of building a Jarvis causes anxiety about not having enough time for yet another project. You see another YouTuber showing off not only a great build but also impressive video production and editing skills. You are suffering from Time Debt, and the solution requires as much discipline and tenacity as escaping from financial debt.

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Open Source LIDAR Lets You Get Down To The Nitty Gritty

February 6, 2019 by 11 Comments

If you’re unfamiliar with LIDAR, you might have noticed it sounds a bit like radar. That’s no accident – LIDAR is a backronym standing for “light detection and ranging”, the word having initially been created as a combination of “light” and “radar”. The average person is most likely to have come into contact with LIDAR at the business end of a police speed trap, but it doesn’t have to be that way. Unruly is the open source LIDAR project you’ve been waiting for all along.

Unlike a lot of starter projects, LIDAR isn’t something you get into with a couple of salvaged LEDs and an Arduino Uno. We’re talking about measuring the time it takes light to travel relatively short distances, so plenty of specialised components are required. There’s a pulsed laser diode, and a special hypersensitive avalanche photodiode that operates at up to 130 V. These are combined with precision lenses and filters to ensure operation at the maximum range possible. Given that light can travel 300,000 km in a second, to get any usable resolution, a microcontroller alone simply isn’t fast enough to cut it here. A specialized  time-to-digital converter (TDC) is used to time how long it takes the light pulse to return from a distant object. Unruly’s current usable resolution is somewhere in the ballpark of 10 mm – an impressive feat.

It’s a complicated project, requiring the utmost attention to detail to get any results at all. The team behind Unruly have done a great job of both designing and documenting the project. It’s great to see an open source LIDAR package in the wild, giving hackers more options than just the pre-baked commercial modules on the market. We can’t wait to see where the project goes next.

For more on LIDAR, check out last week’s Hackaday podcast – we cover Unruly, as well as a handful of other standout projects in the field.

The WiFi Phone That Respects Your Right To Repair

February 6, 2019 by 49 Comments

Phones are getting increasingly more complex, more difficult to repair, and phone manufacturers don’t like you tinkering with their stuff. It’s a portable version of a John Deere tractor in your pocket, and Apple doesn’t want you replacing a battery by yourself. What if there was a phone that respected your freedom? That’s the idea behind the WiPhone, and soon it’s going to be be a crowdfunding campaign. Yes, you will soon be able to buy a phone that respects your freedom.

We took a look at the WiPhone a few months ago, and the idea was solid: make a simple, cheap, handheld device based on the ESP32 WiFi/Bluetooth wonder microcontroller. There are a few other various bits of electronic ephemera for scanning the buttons, an audio codec, and a speaker driver, but the basics of the build are just an LCD and ESP32. The entire idea of this phone is to make calls through WiFi, and given the state of VoIP, it’s a marketable product.

Astute readers may notice that the WiPhone doesn’t have a cellular modem. Yes, this is true, but putting a baseband in a small, low-volume project is incredibly hard. You’re limited to 2G if you don’t want to deal with Broadcom or Qualcomm, and they’re not going to be interested in you if you’re not moving a hundred thousand units, anyway. Also, you’ve got service plans to deal with, multi-country radios, and you’re probably next to a trusted WiFi network right now, anyway.

The WiPhone is designed to be hackable, with daughter boards that turn it into a rainbow or RC car, and easy to assemble. It’s also going to be a crowdfunding campaign at the end of the month. If you want a phone that respects your right to repair, this is the project to look at, even if you don’t need a cellular modem all the time.

This Vintage Phone Goes Cellular

February 5, 2019 by 8 Comments

Way back in the good old days, life ran at a slower pace. It took us almost a decade to get to the moon, and dialling the phone was a lazy affair which required the user to wait for the rotary mechanism to rewind after selecting each digit. Eager to bring a taste of retro telephony into the modern era, [Marek] retrofitted this vintage Polish telephone with a GSM upgrade.

The phone [Marek] salvaged had already been largely gutted, so there was little to lose in the transformation. A Motorola D15 GSM module was sourced from an alarm system to provide a network connection to the project. An Atmega328 was then used to translate the rotary dial mechanics into something more usable by the cellular module.

Attention to detail can really make a project shine, and [Marek] didn’t skimp in this area. The original ringer was rewound to operate with a half H-bridge at a lower voltage more suitable to the modern electronics inside. The microcontroller also helped out by using its PWM hardware to simulate a dialtone and the characteristic sound of pulse dialling.

It’s always nice to see retro hardware given a new lease on life. Unfortunately, GSM networks aren’t long for this world, so a further update may be required before long. These old phones have plenty of potential, as we’ve seen before.