We’ve seen a number of people create plasma speakers over the years here at Hackaday, so at first blush, the latest Plasma Channel video from [Jay Bowles] might seem like more of the same. Even his overview of the assembly of the 555 timer circuit at the heart of the setup, as detailed as it may be, is something we’ve seen before.
But the back half of the video, where [Jay] talks about the flyback transformer used in this plasma speaker, really got our attention. You see, frustrated by the limited options on the market for AC flybacks, he set out to put together a custom transformer utilizing a 3D printed secondary former of his own design.
Armed with a spare core, [Jay] spent some time in CAD coming up with his secondary. Despite never having built a flyback before, his first attempt managed to produce some impressive sparks — that is, until it arced through the printed plastic and released the critical Magic Smoke. Inspired by this early success, he went back to the digital drawing board and cranked his way through several different iterations until he came up with one that didn’t self-destruct.
If you’re looking to experiment with plasma, you’re going to need a high voltage power supply. Usually that means something big, complex, and (naturally) expensive. But it doesn’t have to be. As [Jay Bowles] demonstrates in his latest Plasma Channel video, you can put together a low-cost power supply capable of producing up to 20,000 volts that fits in the palm of your hand. Though you should probably just put the thing down on a table when in use…
The secret to the build is the flyback transformer. A household staple during the era of CRT televisions, these devices can still be readily found online or even salvaged from a broken TV. We’d recommend searching eBay for new old stock (NOS) transformers rather than risk getting blown through a wall while poking around in an old TV you found on the side of the road, but really it all depends on your experience level with this sort of thing.
In any event, once you have the flyback transformer in hand, the rest of the build is very simple. [Jay] demonstrates how you can determine the pinout for your transformer even if you can’t find a datasheet for it, and then proceeds to assemble the handful of ancillary parts necessary to drive it. Housed on a scrap of perfboard and mounted to a piece of plastic to keep stray objects away from the sparky bits underneath, this little power supply would be a reliable workhorse for anyone looking to start experimenting with high voltage. Perhaps an ionic lifter is in your future?
Using nothing more than an antenna, a spark plug, a flyback transformer, a diode, and a car phone charger, [Kreosan] have implemented the world’s most dangerous cell-phone charger: wirelessly charging their phone from high voltage power lines. This is a demonstration of a hack that we thought was just an urban legend, but it’s probably best to leave this as just a demo — this one is probably illegal and definitely dangerous.
The charger works by holding an old TV aerial fairly close to high voltage overhead cables, and passing the resulting tiny current through a spark plug and a flyback transformer to ground. To charge the phone, they tapped the transformer, rectified it through a diode, and fed it into a car-plug phone charger. [Kreosan] claims to harvest enough “free” electricity to charge the phone. (Where by “free”, we mean stolen from the electric grid.)
If you regularly find yourself running out of charge and like a bit of danger why not make a power bank that looks like a bomb instead. Sure we don’t advise you take it on a plane but it seems like a much safer option than using overhead power lines.
In high voltage applications involving tens of thousands of volts, too often people think about the high voltage needed but don’t consider the current. This is especially so when part of the circuit that the charge travels through is an air gap, and the charge is in the form of ions. That’s a far cry from electrons flowing in copper wire or moving through resistors.
Consider the lifter. The lifter is a fun, lightweight flying machine. It consists of a thin wire and an aluminum foil skirt separated by an air gap. Apply 25kV volts across that air gap and it lifts into the air.
Lifter flying with high voltage power supply
So you’d think that the small handheld Van de Graaff generator pictured below, that’s capable of 80kV, could power the lifter. However, like many high voltage applications, the lifter works by ionizing air, in this case ionizing air surrounding the thin wire resulting in a bluish corona. That sets off a chain of events that produces a downward flowing jet of air, commonly called ion wind, lifting the lifter upward.
Having hacked away with high voltage for many years I’ve ended up using a large number of very different high voltage sources. I say sources and not power supplies because I’ve even powered a corona motor by rubbing a PVC pipe with a cotton cloth, making use of the triboelectric effect. But while the voltage from that is high, the current is too low for producing the necessary ion wind to make a lifter fly up off a tabletop. For that I use a flyback transformer and Cockcroft-Walton voltage multiplier power supply that’s plugged into a wall socket.
So yes, I have an unorthodox skillset when it comes to sourcing high voltage. It’s time I sat down and listed most of the power sources I’ve used over the years, including a bit about how they work, what their output is like and what they can be used for, as well as some idea of cost or ease of making. The order is from least powerful to most powerful so keep reading for the ones that really bite.
You’ve no doubt encountered this effect. It’s how your body is charged when you rub your feet on carpet and then get a shock from touching a door knob. When you rub two specific materials together there’s a transfer of electrons from one to the other. Not just any two materials will work. To find out which materials are good to use, have a look at a triboelectric series table.
Materials that are on the positive end of the table will become positively charged when rubbed against materials on the negative end of the table. Those materials will become negatively charged. The further apart they are in the table, the stronger the charging.
[Matt] works at a neon sign power supply company. When a vendor error left him with quite a few defective high voltage transformers, he couldn’t bring himself to toss them in the bin. [Matt] was able to fix the transformers well enough to work, and the idea for a high voltage keyboard began to brew. Unfortunately, the original transformers were not up to the task of creating a musical arc. At that point the project had taken on a life of its own. Matt grabbed some higher power transformers and started building.
The keyboard has 25 keys, each connected to an individual high voltage circuit with its own spark gap. The HV circuit is based upon a IR2153D self-oscillating half-bridge driver. (PDF link). The 2153D is modulated by a good old-fashioned 555 timer chip. No micros in this design, folks! The output of the IR2153D switches a pair of N-channel MOSFETS which drive the flyback transformers.
[Matt] created 25 copies of his circuit and built them up on individual PCBs. He assembled everything on a wooden board shaped roughly like a grand piano. The final project looks great – though [Matt] admittedly has no musical ability, so we can’t hear AC/DC flying out of those spark gaps just yet.
If you do want to hear sparks playing music, check out the OneTesla project we saw at MakerFaire NY 2013.
Let’s be honest. Playing with high voltage is awesome. Dangerous, but awesome — well, as long as you handle it properly. Flyback transformers are a great way to make a nice big electrical arc, but powering them isn’t that easy — or is it?
First off, for those that may not know, a flyback transformer is the type of transformer most commonly found in old TVs and CRT monitors. They typically can put out anywhere from 10kV to 50kV — the problem is, they aren’t that easy to power. Common methods include using a transistor style driver, or zero voltage switching (ZVS) — which is how [Skyy] cooked some s’mores at 50,000V.
As it turns out there’s another much easier and straight forward method. All you need is a fluorescent light ballast. Use the output on the ballast as the input on the primary winding of the flyback transformer — which can be found using a multimeter, just find the highest resistance between pins to identify it. Now because you’re working with such high voltages, you may want to insulate the flyback transformer by submerging it in mineral oil as to not short it out. That’s it.