You Should Not Try These Taser NERF Darts

For most of us, a good part of our childhood involved running around someone’s backyard (or inside the house) trying to score hits with a toy NERF gun. The fun level was high and the risk of personal injury was low. Now that we’re all mostly adults, it’s probably time to take our NERF game to the next level with some risk of serious personal harm.

In an effort to help his brother get back at him for being somewhat of a bully in their youth, [Allen Pan] gifted him with an upgraded NERF gun. Specifically, one with darts that pack a punch. Each of the “Elite” darts was equipped with a 300 V capacitor packed into the interior of the dart. New tips were 3D printed with special metal tips that allow the capacitor to discharge upon impact.

Besides the danger, there’s a good bit of science involved. Parts were scavenged from a new (and surprisingly expensive) disposable camera, and a customized circuit was constructed around the barrel of the dart gun that allows the darts to charge up when they’re loaded. It’s an impressive build that would be relatively simple to reconstruct for yourself, but it’s probably not the worst thing we’ve seen done with high voltage and a few small capacitors.

Thanks to [Itay] for the tip!

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Pocket High Voltage Generator Becomes Great Test Tool

[The LED Artist] often found a need for a relatively high voltage (100 to 200 Volt) but low current DC power supply, and it turns out that a small HV generator that uses a single AA cell only took about an hour to make. The device ended up being a pretty handy tool for testing things like LED filaments (which have a forward voltage of over 60 V), or even neon and nixie tubes.

The device’s low current means that nixie and neon elements won’t light up very brightly, but they will light up enough to verify function and operation. [The LED Artist] reports that touching the output terminals of the generator only causes a slight tingling sensation.

Open-circuit voltage generated from a single AA cell is about 200 V, but that voltage drops rapidly under any kind of load. Even regular LEDs can be safely lit with the circuit, with less than a milliamp being supplied at the two to three volts at which most regular LEDs operate.

[The LED Artist] fit the device into a two-AA battery holder, with a single AA cell on one side and the circuit in the other, and says it’s one of the more useful tools they’ve ever made. LED filaments are fairly common nowadays, but if they intrigue you, don’t forget that [Mike Harrison] covered everything you need to know about experimenting with them.

The Bells! The Bells! One Battery since 1840

It is good advice to change batteries in your fire alarms at least once a year. Even our low-power LCD calculators need new batteries from time to time. But at the University of Oxford, they have an electric bell that has been ringing essentially non-stop on one set of batteries for about 178 years! Is the energy crisis solved then? Perhaps not. The bells require a high voltage but very little current and the pair of batteries — piles in the parlance of 1840 — have kept the charge flowing for about 10 billion rings. As you can see in the video below, though, the ringing isn’t very vigorous.

How does it work? When you think of converting electrical power to mechanical motion you probably think of a motor, even though there are plenty of other transducers like speakers, muscle wires, and solenoids. Arguably the first device was electrostatic bells that were invented by a Scot named [Andrew Gordon] around 1742. [Ben Franklin] made them famous, though, so they are often called Franklin bells.

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Add Some Edge To Your Blades With Blown-Arc Plasma

If you polled science fiction fans on what piece of technology portrayed by the movies that they most desire, chances are pretty good that the lightsabers from the Star Wars franchise would be near the top of the list. There’s just something about having that much power in the palm of your hand and still needing to be up close and personal to fight with it. Plus being able to melt holes in bulkheads is pretty keen, as are the cool sounds.

Sadly, the day we can shape and contain plasma in a blade-shaped field is probably pretty far off, but that didn’t stop [Alan Pan] from trying the next best thing: a handheld plasma-projecting blade. He starts with a basic Jacob’s ladder. We’ve seen many of these before, but the basic idea is to ionize the air between two parallel, vertical conductors; the hot plasma heats the air causing it to rise until it reaches the top and snuffs itself out, starting the process over again at the bottom. His twist is to force the plasma into a sheet between the electrodes with air from a leaf blower, forming a blown-arc plasma. That’s pretty cool looking by itself, but he also stretched the electrodes along razor-sharp wood planer blades, for extra danger. We have to admit that the thing looks pretty intimidating, even if the plasma doesn’t really pack bulkhead-melting thermal power. Check out the results in the video below.

We’d love to see [Alan] make good on his promise to make the whole thing self-contained with an electric ducted fan or mini jet engine. Even as it is, it’s still pretty neat. It’s not really his first lightsaber rodeo, but at least this one doesn’t need butane.

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A Look at Liquid Dielectrics

One evening quite a few years ago, as I was driving through my hometown I saw the telltale flashing lights of the local volunteer fire department ahead. I passed by a side road where all the activity was: a utility pole on fire. I could see smoke and flames shooting from the transformer and I could hear the loud, angry 60 Hz buzzing that sounded like a million hornet nests. As I passed, the transformer exploded and released a cloud of flaming liquid that rained down on the road and lawns underneath. It seemed like a good time to quit rubbernecking and beat it as fast as I could.

I knew at the time that the flaming liquid was transformer oil, but I never really knew what it was for or why it was in there. Oil is just one of many liquid dielectrics that are found in a lot of power distribution equipment, from those transformers on the pole to the big capacitors and switchgear in the local substation. Liquid dielectrics are interesting materials that are worth taking a look at.

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Let No Eyebrow Go Unsinged With A Wrist-Mounted Flamethrower

We’ll say it just once, and right up front: wrist-mounted flamethrowers are a bad idea. An itchy nose and a brief moment of forgetfulness while sporting one of these would make for a Really Bad Day. That said, this flaming gauntlet of doom looks like a lot of fun.

We’ve got to hand it to [Steve Hernandez] – he put a lot of work into the Flame-O-Tron 9000. Building on his prior art in the field, [Steve] went a bit further with this design. The principle is the same – butane plus spark equals fun – but the guts of this flamethrower are entirely new. A pipe bomb custom fuel tank is used rather than the stock butane can, and a solenoid valve controls fuel flow. Everything lives in a snazzy acrylic case that rides on a handmade leather bracer, and controls in the hand grip plus an Arduino allow the user to fire short bursts of flame or charge up for a real fireball. See what you think of the final product in the short video after the break; it sounds as though even if the fuel runs out, the high-voltage would make a dandy stun gun.

Maybe we should lay off the safety nagging on these wrist rockets. After all, we’ve seen many, many, many of them, with nary a report of injury.

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Perf Board Pyrotechnics Courtesy of a High-Voltage Supply

You may have asked yourself at one time or another, “Self, what happens when you pass 100 thousand volts through a printed circuit board?” It’s a good question, and [styropyro] put together this fascinating bit of destructive testing to find out.

Luckily, [styropyro] is well-positioned to explore the high-voltage realm. His YouTube stock-in-trade is lasers, ranging from a ridiculously overpowered diode-laser bazooka to a bottle-busting ruby laser. The latter requires high voltage, of course, and his Frankenstein’s lab yielded the necessary components for this destructive diversion. A chopper drives dual automotive ignition coils to step the voltage up to a respectable 100 kV. The arcs across an air gap are impressive enough, but when applied to a big piece of copper-clad protoboard, the light show is amazing. The arcs take a seemingly different path across the board for each discharge, lighting up the path with an eerie blue glow accompanied by a menacing buzz. Each discharge path may be random, but they all are composed of long stretches across the rows and columns of copper pads that never take the more direct diagonal path. [styropyro]’s explanation of the math governing this behavior is feasible, but really we just liked looking at the pretty and dangerous display. Now if only the board had been populated with components…

No, there’s not much of a hack here, but it’s cool nonetheless. And it’s probably a well-earned distraction from his more serious stuff, like his recent thorough debunking of the “Chinese laser rifle” that was all over the news a while back.

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