Kitty Litter And Broken Light Bulbs Power This Homebrew Gas Chromatograph

August 8, 2019 by Dan Maloney 29 Comments

We’re always on the lookout for unexpected budget builds here at Hackaday, and stumbling across a low-cost, DIY version of an instrument that sells for tens of thousands of dollars is always a treat. And so when we saw a tip for a homebrew gas chromatograph in the tips line this morning, we jumped on it. (Video embedded below.)

For those who haven’t had the pleasure, gas chromatography is a chemical analytical method that’s capable of breaking a volatile sample up into its component parts. Like all chromatographic methods, it uses an immobile matrix to differentially retard the flow of a mobile phase containing the sample under study, such that measurement of the transit time through the system can be made and information about the physical properties of the sample inferred.

The gas chromatograph that [Chromatogiraffery] built uses a long stainless steel tube filled with finely ground bentonite clay, commonly known as kitty litter, as the immobile phase. A volatile sample is injected along with an inert carrier gas – helium from a party balloon tank, in this case – and transported along the kitty litter column by gas pressure. The sample interacts with the column as it moves along, with larger species held back while smaller ones speed along. Detection is performed with thermal conductivity cells that use old incandescent pilot lamps that have been cracked open to expose their filaments to the stream of gas; using a Wheatstone bridge and a differential amp, thermal differences between the pure carrier gas and the eluate from the column are read and plotted by an Arduino.

The homebrew GC works surprisingly well, and we can’t wait for [Chromatogiraffery] to put out more details of his build.

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Fail Of The Week: Spinning The Pripyat Ferris Wheel

August 7, 2019 by Tom Nardi 67 Comments

This multifaceted fail comes to us straight from the Chernobyl Exclusion Zone, where a group of friends apparently decided that a fun weekend project would be trying to turn over the iconic ferris wheel in the Pripyat Amusement Park. The [Kreosan] crew documented their admittedly very creative attempt at suicide in the video after the break, but we can save you some time by telling you right up front that the decades-old ferris wheel never actually rotates more than a few degrees. Though that’s hardly the key failure of this endeavour.

Even if you don’t understand anything they’re saying (we certainly don’t), it’s not too hard to follow along with this harebrained scheme.

Under cover of darkness, the troupe gains access to the mechanisms below the towering Soviet-era ride, and removes the brake unit mounted next to the motor. With the wheel now free spinning, the team is elated to see the mechanical advantage is such that spinning the shaft by hand is enough to cause a very slight rotation of the pulley and cables attached to the wheel.

Realizing they need more speed, the group then spends the rest of the night and apparently a good deal of the following day attempting to spin the mechanism using the rear wheel of one of their electric bicycles. But a rubber wheel held by hand against a rusty shaft, rather unsurprisingly, turns out to be a fairly poor mechanical linkage. They get a couple partial rotations on the pulleys, but still no serious movement.

One of the guys was working on the next phase of the inexplicably misguided plan, removing some heavy counterweights hanging under the ferris wheel, when a young woman shows up with a dosimeter and starts taking some measurements. Eventually, one of these moonlighting ferris wheel engineers uses the meter to observe the elevated radiation levels of the dirt and rust accumulated on his bare hands. This swiftly brings the operation to a close, and they all ride off on their bikes.

This was, without question, a monumentally stupid thing to do. Even if this was just a run-of-the-mill ferris wheel that had been abandoned and exposed to the elements for over thirty years, climbing on the thing and trying to get it to spin would be dangerous. But when you combine that with the fact it’s common knowledge to those who explore the Exclusion Zone that there are parts of the ferris wheel still emitting radiation at hundreds of times the normal background dose, this misadventure is a strong contender for the 2019 Darwin Award.

We’re lucky the remnants of Chernobyl’s number four reactor are locked away inside the Chernobyl New Safe Confinement, or else some up-and-coming Internet celebrity might try to get in there and spin up the turbines for a laugh. We’ve seen some pretty crazy stunts from [Kreosan], and we’d like to see more. So please, stay safe(r) guys!

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Quilting Desk Is An Absolute Unit

August 1, 2019 by Kristina Panos 10 Comments

Most hobbies come with a lot of tools, and thread injecting is no different. Quilting itself may be Queen Hobby when it comes to the sheer volume of things you can buy: specialized templates, clips, thimbles, disappearing ink pens, and so on. And of course, you want it all within arm’s reach while sitting at the machine.

Years ago, [KevsWoodworks] built an impressive custom quilting desk for his wife. He’d added on to it over the years, but it was time for a bigger one. This beautiful beast has 21 drawers and 6 large cubbyholes for plastic bins. At the wife’s request, one of the drawers is vertical. [Kev] doesn’t say what she put in there, but if it were our desk, that’s where we’d stash all our large plastic rulers that need to be kept flat (or vertical). There’s also a lift, so any sewing machine can be brought up flush with the enormous top.

Fortunately for us, [Kev] likes to teach. He documented the build in a series of videos that go nicely with his CAD drawings, which are available for download. Thread your way past the break to see those videos.

Want to do some thread injecting, but don’t want to spend hundreds on a machine? We got lucky with our entry-level injector. If yours is a piece of scrap or has limited stitch options, replace the motor, or add an Arduino.

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Reon Pocket Keeps You Cool With A Peltier Element

August 1, 2019 by Maya Posch 53 Comments

With another summer of heatwaves leaving its mark on our planet, finding a way to stay cool during the day isn’t an easy task. From the morning and afternoon commute in public transport, to busy crowds outside during lunch hour, there are many times when you cannot just find a place inside an airconditioned room to deal with the heat. Exactly for this purpose Sony has successfully completed a kickstarter (in Japanese) on its corporate ‘First Flight’ crowdfunding platform for the Reon Pocket.

Many people probably aren’t aware of Sony’s crowdfunding platform, but it’s a way to gauge the interest from the public for more ‘out there’ products, which do not fit Sony’s usual business model. In this case the Reon Pocket is a Peltier-based device which is placed against the back of one’s neck, from where it can either lower or increase the body’s temperature, reportedly by -13 ℃ and +8.3 ℃ respectively.

Covered in more detail by Engadget and its Japanese sister site, the reported 24 hour battery life refers to the Bluetooth link that connects the device with one’s smartphone, whereas the battery lasts under two hours with the peltier element active. This is probably not too shocking to anyone who knows how a peltier element functions, and how much electricity they consume.

Still, the basic concept seems sound, and there are functioning prototypes. While a 2-hour battery life isn’t amazingly long, it can be just the thing one needs to keep one’s cool during that 15 minute walk to the office in a three-piece suit, without needing a shower afterwards. The device isn’t expensive either, with a projected ¥12,760 (about $117) supplied. Naturally the device will only be on sale in Japan.

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Lego-Powered Sub Built In A Water Jug

July 28, 2019 by Lewin Day 16 Comments

Submarines are universally considered cool, but bring several challenges to the RC modeller that aren’t there with land and air builds. Water ingress can ruin your project, and there’s always the possibility of it sinking to the bottom, never to return. That didn’t phase [Brick Experiment Channel], however, and thus a Lego sub was born. (Video embedded below the break.)

The sub uses a water jug as a hull. The video steps through the process of sealing the hull itself, before dealing with sealing the rotating propeller shafts. A large syringe is used as a ballast tank, with Lego motors used to actuate the tank and provide propulsion and steering. An existing RC submarine is cannabilized for parts, providing the necessary radio control hardware.

In testing, the sub performs admirably, with a few final tweaks necessary to improve the performance of the propellers. It’s not winning any races anytime soon, but it’s a functional underwater explorer that we’d love to take down the lake ourselves sometime.

We’ve seen Lego subs built before, even including missiles.

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Popstick Fan Car Is A Fun Bluetooth Build

July 25, 2019 by Lewin Day 5 Comments

Archer fans already know, but for the rest of the world it bears saying – boats are fine, but fan boats are better. It’s much the same with land vehicles, too. [tinkeringtech] felt the same way, and built a Bluetooth-controlled fan car to scoot around the floor. (YouTube, embedded below.)

Construction starts with a series of popsticks glued together to create a chassis. Twist ties are then used to act as axles for bottle cap wheels, while steering is handled by a cardboard rudder controlled by a servo. Propulsion is via a pair of pager-sized motors fitted with fans. An Adafruit Bluefruit Feather M0 runs the show, receiving commands over Bluetooth and driving the motors through an H-bridge chip in the center of the vehicle.

It’s a fun craft-style build that would be a great project for kids interested in electronics and making. It teaches basic electronics, as well as serving as a good introduction into the world of microcontrollers. It’s one of the smaller radio-controlled builds we’ve seen, but you can always go full-scale if that takes your fancy.

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Reaction Trainer Keeps You On Your Toes

July 24, 2019 by Lewin Day 1 Comment

In many sports, it’s important for competitors to be light on their feet, and able to react quickly to external stimuli. It all helps with getting balls in goals, and many athletes undergo reaction drills as part of their training regime. To help with this, [mblaz] set out to build a set of reaction trainers.

The training setup consists of a series of discs, each with glowing LEDs and a proximity sensor. The discs randomly light up, requiring a touch or wave to switch them off. At this point, another disc will light randomly, and so on.

The discs are built using an ATmega328 to run the show, with NRF24L01+ radios used to communicate between the modules. High brightness red LEDs are used for indication. An optical proximity sensor is used for its fast reaction time and low cost, while power comes via a small lithium polymer battery integrated into each disc.

We’re sure [mblaz] and his fellow athletes will find the rig to be useful in their training. There’s plenty of scope for electronics to help out with athletic training; this boxing trainer is a great example. If you’ve got a great sports engineering project of your own, don’t hesitate to send it in!