Is It A Plasma Tweeter Or A Singing Tesla Coil?

June 19, 2021 by Jenny List 6 Comments

When our ears resolve spatial information, we do so at the higher treble frequencies rather than the bass. Thus when setting up your home cinema you can put the subwoofer almost anywhere, but the main speakers have to project a good image. The theoretical perfect tweeter for spatial audio is a zero mass point source, something that a traditional speaker doesn’t quite achieve, but to which audio engineers have come much closer with the plasma tweeter. This produces sound by modulating a small ball of plasma produced through high-voltage discharge, and it’s this effect that [mircemk] has recreated with his HF plasma tweeter.

A look at the circuit diagram and construction will probably elicit the response from most of you that it looks a lot like a Tesla coil, and in fact that’s exactly what it is without the usual large capacitor “hat” on top. This arrangement has been used for commercial plasma tweeters using both tubes and semiconductors, and differs somewhat from the singing Tesla coils you may have seen giving live performances in that it’s designed to maintain a consistent small volume of discharge rather than a spectacular lightning show to thrill an audience.

You can see it in operation in the video below the break, and it’s obvious that this is more of a benchtop demonstration than a final product with RF shielding, It’s not the most efficient of devices either, but given that audiophiles will stop at nothing in their pursuit of listening quality, we’d guess that’s a small price to pay. Efficiency can be improved with a flyback design, but for the ultimate in showing off how about a ring magnet to create the illusion of a plasma sheet?

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Physics Of Lightning Hack Chat

March 29, 2021 by Dan Maloney 2 Comments

Join us on Wednesday, March 31 at noon Pacific for the Physics of Lightning Hack Chat with Greg Leyh!

Of all the things that were around to terrify our ancestors, lightning must have been right up there on the list. Sure, the savannahs were teeming with things that wanted to make lunch out of you, but to see a streak of searing blue-white light emerge from a cloud to smite a tree out of existence must have been a source of dread to everyone. Even now, knowing much more about how lightning happens and how to protect ourselves from it, it’s still pretty scary stuff to be around.

But for as much as we know about lightning, there are plenty of unanswered questions about its nature. To get to the bottom of this, Greg Leyh wants to build a lightning machine of gargantuan proportions: a pair of 120 foot (36 m) tall Tesla towers. Each 10-story tower will generate 8.8 million volts and recreate the conditions inside storm clouds. It’s an ambitious goal, but Greg and his team at Lightning on Demand have already built and demonstrated a 1/3-scale prototype Tesla tower, which is impressively powerful in its own right.

As you can imagine, there are a ton of engineering details that have to be addressed to make a Tesla tower work, not to mention the fascinating physics going on inside a machine like this. Greg will stop by the Hack Chat to answer our questions about the physics of lightning, as well as the engineering needed to harness these forces and call the lightning down from the sky.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, March 31 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
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Electric Candle Replaces Flame With Plasma

February 1, 2021 by Dan Maloney 32 Comments

Ah, the charm of candlelight! Nothing says “romance” — or “extended power outage” — like the warm, soft glow of a real candle. But if you’re not a fan of burning wax for whatever reason, this electric plasma candle may be just the thing to build for your next dinner for two.

This re-imagining of the humble candle comes to us by way of plasma super-fan [Jay Bowles], who has a lot of experience with plasmas and the high-voltage circuits that often go along with them. Even so, he had to enlist help with the circuit, with is essentially a 10-MHz Class-E oscillator, from [Leon] at the Teslaundmehr channel on YouTube. The most prominent feature of the build is the big resonator coil, surrounded by the shorter primary coil and sitting atop the heatsink for the MOSFET driver. [Jay]’s usual acrylic-rich style is well represented here, and the resulting build is quite lovely.

The tuning process, though, sounds like it was pure torture. It took a lot of tweaking — and a lot of MOSFETs — to get the candle to produce a stable flame. But once it did, the results were striking. The plasma coming off the breakout point on the resonator coil is pretty much the same size, shape, and — occasionally — the color as a candle flame. It’s also hot enough to do some damage, so do be careful if you build this. We’ve included both [Jay]’s and [Leon]’s videos below; [Leon]’s has great step-by-step build instructions.

We’ve been following [Jay]’s journey through the plasmaverse for a while now, from his cheap and simple Tesla coils to using corona discharge to clean his hands. He even hosted a Hack Chat on the subject last year.

Note: [Jay] reached out to us after publication about mitigating RF noise. He does his experiments inside a steel-reinforced concrete building with grounded metal screens over the windows. An RF-wizard friend has checked across the spectrum and detected no leaks to the outside. Sounds like the business to us.

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Extremely Simple Tesla Coil With Only 3 Components

January 12, 2021 by Anool Mahidharia 22 Comments

Tesla Coils are a favourite here at Hackaday – just try searching through the archives, and see the number of results you get for all types of cool projects. [mircemk] adds to this list with his Extremely simple Tesla Coil with only 3 Components. But Be Warned — most Tesla coil designs can be dangerous and ought to be handled with care — and this one particularly so. It connects directly to the 220 V utility supply. If you touch any exposed, conductive part on the primary side, “Not only will it kill You, it will hurt the whole time you’re dying”. Making sure there is an ELCB in the supply line will ensure such an eventuality does not happen.

No prizes for guessing that the circuit is straight forward. It can be built with parts lying around the typical hacker den. Since the coil runs directly off 220 V, [mircemk] uses a pair of fluorescent lamp ballasts (chokes) to limit current flow. And if ballasts are hard to come by, you can use incandescent filament lamps instead. The function of the “spark gap” is done by either a modified door bell or a 220 V relay. This repeatedly charges the capacitor and connects it across the primary coil, setting up the resonant current flow between them. The rest of the parts are what you would expect to see in any Tesla coil. A high voltage rating capacitor and a few turns of heavy gauge copper wire form the primary LC oscillator tank circuit, while the secondary is about 1000 turns of thinner copper wire. Depending on the exact gauge of wires used, number of turns and the diameter of the coils, you may need to experiment with the value of the capacitor to obtain the most electrifying output.

If you have to look for one advantage of such a circuit, it’s that there is not much that can fail in terms of components, other than the doorbell / relay, making it a very robust, long lasting solution. If you’d rather build something less dangerous, do check out the huge collection of Tesla Coil projects that we have featured over the years.

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This (mostly) Transparent Tesla Coil Shows It All

October 20, 2020 by Tom Nardi 11 Comments

You’d be forgiven for assuming that a Tesla coil is some absurdly complex piece of high-voltage trickery. Clarke’s third law states that “any sufficiently advanced technology is indistinguishable from magic”, and lighting up a neon tube from across the room sure looks a lot like magic. But in his latest Plasma Channel video, [Jay Bowles] tries to set the record straight by demonstrating a see-through Tesla coil that leaves nothing to the imagination.

Of course, we haven’t yet mastered the technology required to produce transparent copper wire, so you can’t actually see through the primary and secondary coils themselves. But [Jay] did wind them on acrylic tubes to prove there aren’t any pixies hiding in there. The base of the coil is also made out of acrylic, which lets everyone see just how straightforward the whole thing is.

Beyond the coils, this build utilizes the DIY high-voltage power supply that [Jay] detailed a few months back. There’s also a bank of capacitors mounted to a small piece of acrylic, and a clever adjustable spark gap that’s made of little more than a few strategically placed pieces of copper pipe and an alligator clip. Beyond a few little details that might not be obvious at first glance, such as grounding the secondary coil to a layer of aluminum tape on the bottom of the base, it’s all right there in the open. No magic, just science.

[Jay] estimates this beauty can produce voltages in excess of 100,000 volts, and provides a demonstration of its capabilities in the video after the break. Unfortunately, before he could really put the new see-through coil through its paces, it took a tumble and was destroyed. A reminder that acrylic enclosures may be pretty, but they certainly aren’t invulnerable. With the value of hindsight, we’re sure the rebuilt version will be even better than the original.

If you’d rather not have your illusions shattered, we’ve seen plenty of complex Tesla coils to balance this one out. With witchcraft like PCB coils and SMD components, some of them still seem pretty magical.

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Into The Plasmaverse Hack Chat

September 21, 2020 by Dan Maloney 1 Comment

Join us on Wednesday, September 23 at noon Pacific for the Into the Plasmaverse Hack Chat with Jay Bowles!

Most kids catch on to the fact that matter can exist in three states — solid, liquid, and gas — pretty early in life, usually after playing in the snow a few times. The ice and snowflakes, the wet socks, and the fog of water vapor in breath condensing back into water droplets all provide a quick and lasting lesson in not only the states of matter but the transitions between them. So it usually comes as some surprise later when they learn of another and perhaps more interesting state: plasma.

For the young scientist, plasma is not quite so easy to come by as the other phases of matter, coming about as it does from things they’re usually not allowed to muck with. High voltage discharges, strong electromagnetic fields, or simply a lot of heat can strip away electrons from a gas and make the ionized soup that we call plasma. But once they catch the bug, few things can compare to the dancing, frenetic energy of a good plasma discharge.

Jay Bowles picked up the plasma habit quite a while back and built his YouTube channel around it. Tesla coils, Van de Graaff generators, coils and capacitors of all types — whatever it takes to make a spark, Jay has probably made and used it to make the fourth state of matter. He’ll join us on the Hack Chat to talk about all the fun things to do with plasma, high-voltage discharge, and whatever else sparks his interest.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, September 23 at 12:00 PM Pacific time. If time zones baffle you as much as us, we have a handy time zone converter.

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Tesla Coil Electric Bike Is Wireless

September 9, 2020 by Bryan Cockfield 28 Comments

Electric bikes, and really all electric vehicles, have one major downside: the weight and cost of batteries. Even with lithium, battery packs for ebikes can easily weigh more than the bike itself and cost almost as much. But having to deal with this shortcoming could be a thing of the past thanks to [LightningOnDemand]’s recent creation. Of course, this would rely on a vast infrastructure of Tesla coils since that’s how this bike receives the power it needs to run its electric motor.

The Tesla coil used for the demonstration is no slouch, either. It’s part of the Nevada Lightning Laboratory and can pack a serious punch (PDF warning). To receive the electrical energy from the coil, the bike (actually a tricycle) uses a metal “umbrella” of sorts which then sends the energy to the electric motor. The bike drags a chain behind itself in order to have a ground point for the electricity to complete its circuit. There is limited range, though, and the Tesla coil will start ionizing paths to the ground if the bike travels too far away.

While we can’t realistically expect Tesla’s idea of worldwide, free, wireless electricity to power our bicycles anytime soon, it is interesting to see his work proven out, even if its on a small scale like this. Of course, it doesn’t take a research laboratory to start working with Tesla coils. This one is built out of common household parts and still gets the voltages required to create the signature effects of a Tesla coil.

Thanks to [Adam] for the tip!

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