Microwave Ovens Turn You into Spiderman

Want to climb a wall like Spiderman? No problem – just whip up a climbing rig with microwave oven transformers. And find a steel building. And rewrite the canon so that Peter Parker is bitten by an electromagnetic spider instead of a radioactive one.

Back in the reality-based world, you’d probably be taking you life in your hands if you use [Make It Extreme]’s rig to get more than a dozen feet above the ground. The basics are pretty sound, but the devil is in the details. Four MOTs are cut and stripped of their secondary coils and attached to fixtures for the feet and hands. A backpack full of gel cell batteries powers the rig, and simple normally closed switches in the handholds control both the foot and hand magnets on a side.  A click of a switch releases the magnets on one side, allowing the climber to reach up.

And therein lies our safety beef: what happens when you make a mistake and push both buttons at the same time? Seems like this build is screaming for some control circuitry that prevents this most obvious failure mode. We’re not ones to throw an Arduino at every problem, but in this case it may make sense, especially when it could monitor your time left before cratering the charge remaining in the battery pack.

Still, like most dangerous stunts, this looks really cool. If you’ve got any ideas for improvements in the controls, leave them in the comments below. And if you’re interested in transforming yourself into a superhero, learn from a guy who’s actually doing it – our own [James Hobson]. Check out some of his builds, like the Captain America shield or his car-lifting exoskeleton.

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Pneumatic Launcher Gets Ham Antennas Hanging High

Amateur radio is an eclectic hobby, to say the least. RF propagation, electrical engineering, antenna theory – those are the basics for the Ham skillset. But pneumatics? Even that could come in handy for hanging up antennas, which is what this compressed-air cannon is designed to do.

[KA8VIT]’s build will be familiar to any air cannon aficionado. Built from 2″ Schedule 40 PVC, the reservoir is connected to the short barrel by a quarter-turn ball valve. Charging is accomplished through a Schrader valve with a cheap little tire inflator, and the projectile is a tennis ball weighted with a handful of pennies stuffed through a slit. Lofting an antenna with this rig is as simple as attaching a fishing line to the ball and using that to pull successively larger lines until you can pull the antenna itself. [KA8VIT] could only muster about 55 PSI and a 70′ throw for the first attempt shown below, but a later attempt with a bigger compressor got him over 100 feet. We’d guess that a bigger ball valve might get even more bang for the buck by dumping as much air as quickly as possible into the chamber.

Looking to launch a tennis ball for non-Ham reasons? We’ve got you covered whether you want to power it with butane or carbon dioxide.

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Watch The Diesel Effect in Ballistic Gelatin

A striking video appears to demonstrate an explosion via the diesel effect in clear ballistic gel. The diesel effect or “dieseling” refers to when a substance ignites from the effects of pressure, and it’s the operating principle behind the gadgets known as Fire Sticks or Fire Pistons.

diesel-effect-ballistics-gelBallistic gel is a broad term referring to a large chunk of dense gel generally used in firearms-related testing to reliably and consistently measure things like bullet deformation, fragmentation, and impact. It’s tough, elastic, and in many ways resembles a gigantic gummi bear. Fans of Mythbusters (or certain DIY railguns) will recognize the stuff. Water-based blocks made with natural gelatin can be easily made at home, but end up with a yellow-brown color and have a limited shelf life due to evaporation. Clear blocks exist that are oil-based and don’t dry out like the water-based ones. It’s one of these that is in the embedded animation below.

Slow motion video capture is a natural companion to just about anything that you’d need ballistic gel for, and good thing — because the video captured what appears to be a diesel effect! The block is hit with a bullet, and as the bullet rapidly expands and dumps its energy into the gel, a cavity expands rapidly. During this process, some of the (oil-based) material in the cavity has been vaporized. After the expanded bullet exits (to the right of the gif above but easier to see in the video below), the cavity in the block begins to collapse. The resulting pressure increase appears to ignite the vaporized material, which explodes with a flash followed by some exhaust.

This effect has been observed in ballistic gel before, but this video shows a particularly clear ignition, followed by a secondary expansion of the cavity, then a flatulent-ish ejection of exhaust as the cavity collapses. If nothing else, it’s a very striking effect clearly captured on film. Slow-motion capture of destructive forces makes visible many things that would otherwise happen too quickly to perceive.

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An Easy Home Made Electroadhesive

There was a time when if you wanted to scale a wall you had to turn a camera on its side and call [Adam West] or [Lionel Ritchie]. Unless you were a gecko, that is. Their host of tiny bristles and intramolecular forces allow them to run up walls and across the ceiling with ease.

You may have seen synthetic gecko-like adhesive surfaces using the same effect. Some impressive wall-climbing robots have used these materials, though they’ve all shared the same problem. Gecko adhesion can’t be turned off. Happily, for the robot wall climber unwilling to expend the extra force to detach a foot there is an alternative approach. Electroadhesives use electrostatic force to attach a plate held at a high potential to a surface, and today’s featured video is [Carter Hurd]’s home-made electroadhesive panel (YouTube).

He cites this paper and this description of the technology as the influences on his design, two aluminium foil electrodes sandwiched between plastic sheet and sticky tape. He applies 6kV from an Emco DC to DC converter to his plates, and as if by magic it sticks to his drywall. Of course, it’s not quite as simple as that, he tried several surfaces before finding the one it stuck to. Adhesion is fully under control, and such a simple device performs surprisingly well. The Emco converters are sadly not cheap, but they are an extremely efficient product for which he only needs a few AA cells on the low voltage side.

His full description is in the video below the break.

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Peculiar Fluid Dynamics Creates Hot and Cold Air

We’re fascinated by things with no moving parts or active components that work simply by virtue of the shape they contain — think waveguides and resonators for microwave radiation. A similarly mystical device from the pneumatics world is the Hilsch Vortex Tube, and [This Old Tony] decided to explore its mysteries by whipping up a DIY version in his shop.

Invented in the 1930s, vortex tubes are really just hollow tubes with an offset swirl chamber. Incoming compressed air accelerates in the swirl chamber and heads up the periphery of the long end of the tube, gaining energy until it hits a conical nozzle. Some of the outer vortex escapes as hot air, while the rest reflects off the nozzle and heads back down the pipe as a second vortex inside the outer one. The inner vortex loses energy and escapes from the short end as a blast of cold air – down to -50°C in some cases. [Tony]’s build doesn’t quite approach that performance, but he does manage to prove the principle while getting a few good-natured jabs into fellow vloggers [AvE] and [Abom79].

We’ve covered vortex tubes before, but as usual [Tony]’s build shines because he machines everything himself, and because he tries to understand what’s making it work. The FLIR images and the great video quality are a bonus, too.

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Two Words That Don’t Mean What You Think They Do

sprites_enhanced_stripWhen you hear “gravity waves” or “sprites”, you’d think you would know what is being discussed. After all, those ripples in space-time that Einstein predicted would emanate from twin, colliding, black holes were recently observed to much fanfare. And who doesn’t love early 8-bit computer animations? So when we were browsing over at SpaceWeather we were shocked to find that we were wrong twice, in one photo (on the right). Continue reading “Two Words That Don’t Mean What You Think They Do”