[GreatScott!] needs to light off fireworks with an arc rather than a flame, because “fireworks and plasma” is cooler than fireworks and no plasma. To that end, he attempted to reverse engineer an arc lighter, but an epoxy potted high-voltage assembly thwarted him. Refusing to accept defeat, he modified a CCFL inverter into an arc lighter, and the process is pretty educational.
With his usual impeccable handwriting and schematic drawing skills, [GreatScott!] documents that his CCFL inverter is a resonant Royer oscillator producing a sine wave of about 37 kHz, which is then boosted to about 2400 volts. That’s pretty good, but nowhere near the 15 kilovolts needed for a self-sustaining arc across electrodes placed 5 mm apart. A little math told him that he could achieve this by rewinding the transformer’s primary with only 4 turns. After some testing, the rewound transformer was fitted back into the Royer circuit and with a few modifications the arc was struck.
It’s not a finished project yet, and we’re looking forward to seeing how [GreatScott!] puts this to use. For now, we’re grateful for the lesson is Royer oscillators and rewinding transformers. But if you’d rather hack an off-the-shelf arc lighter, there’s always this arc lighter pyrography pen, or this mini plasma cutter.
I work a lot with high voltages and others frequently replicate my projects, so I often get asked “What voltage is needed?”. That means I need to be able to measure high voltages. Here’s how I do it using a Fluke high voltage probe as well as my own homemade probe. And what if you don’t have a probe? I have a solution for that too.
How Long Is Your Spark?
The simplest way to measure high voltage is by spark length. If your circuit has a spark gap then when a spark occurs, that’s a short-circuit, dumping all your built up charge. When your spark gap is at the maximum distance at which you get a spark then just before the spark happens is when you have your maximum voltage. During the spark the voltage rapidly goes to zero and depending on your circuit it may start building up again. The voltage before the spark occurred is related to the spark length, which is also the spark gap width.
The oscilloscope photo below shows this changing voltage. This method is good for a rough estimate. I’ll talk about doing more precise measurements when I talk about high voltage probes further down.
It’s generally a bad idea to mix high voltage electricity and water, but interesting things happen if you do. This video from [RWGResearch] shows one of them: water bridging. If you have two water sources (such as two beakers full of very highly distilled water) with a high voltage between them, the voltage can create a gravity defying bridge that flows between them.
The experiment starts with the pouring spouts from two beakers nearly touching each other. Water fills the beakers right up to the spout, but it’s the application of electricity that pulls the bridge between the positive and negative beakers. With care, this technique can create a bridge of up to 2cm (about 0.8 inches). [RWGResearch] shows that he is able to create a bridge of about a centimeter with a 5KV voltage, but which only carries a few milliamps.
What forces are at play here isn’t exactly clear, but one recent paper speculates that it’s down to a combination of the dielectric force caused by the differing charges of parts of water molecules and the surface tension of the water. Whatever it is, it is fascinating and makes for a neat trick.
Want to make your own contribution to the scientific body of knowledge? Prove or disprove the speculation mentioned in the Wikipeadia article: is this possible because of an H3O2 lattice formed by the high voltage? How would you formulate a test for this?
Everybody loves plasma globes, but if you are like [zrgzhv], building them as large as possible is the challenge! Definitely a beautiful project, at 7 feet long and 1 foot in diameter, this monster tube makes an impressive display of plasma filaments that slowly move inside. Heck, they almost seem to be alive following the movements of his hand and it’s hard not to become mesmerized by the motion.
This tube follows the same principle of operation as its smaller cousin, the plasma globe. Air is evacuated and the tube is filled with a mixture of noble gases, with the particular mixture being responsible for the color of the filaments. Then, high voltage AC is applied to an electrode, which causes the moving tendrils of colored light to extend from the electrode to the outer glass, a phenomenon known as glow discharge. In general, gas-filled tubes can have other uses such as lightning — in the form of fluorescent, neon and xenon lamps — or high power switching as in the thyratron tube, among other applications.
The tube has a weight of over 65 pounds, and needs 300 watts of power to operate from an also homemade power supply. In another video, you can see 10 tubes of different colors working at once. Plasma always makes a great attention-getter; another nice example of its use can be seen in this steampunk lamp which incorporates rotating contacts on the outside of the glass.
Taking a break from his book, “How to Gain Enemies and Encourage Hostility,” [FPS Weapons] shows us how to build our own handheld EMP generator which can be used to generate immediate dislike from anyone working on something electronic at the hackerspace.
The device is pretty simple. A DC source, in this case an 18650 lithium battery cell, sends power to an “Ultra High Voltage 1000kV Ignition Coil” (as the eBay listing calls it), when a button is pressed. A spark gap is used to dump a large amount of magic pixies into the coil all at once, which generates a strong enough magnetic pulse to induce an unexpected voltage inside of a piece of digital electronics. This usually manages to fire a reset pin or something equivalent, disrupting the device’s normal operation.
While you’re not likely to actually damage anything in a dramatic way with this little EMP, it can still interrupt an important memory write or radio signal and damage it that way. It’s a great way to get the absolute shock of your life if you’re not careful. Either from the HVDC converter or the FCC fines. Video after the break.
As children, we all probably had our ideal career paths. As an adult do you still harbor a secret desire to be an astronaut, or to drive a railroad train? Or have holders of other jobs become the people you envy?
As a Hackaday writer it’s probably not too controversial to admit a sneaking envy for the writers of semiconductor application notes. True, often their work consists of dry demonstrations of conventional uses for the products in question, but every once in a while they produce something off the wall and outside the device’s intended use, so out of the ordinary that you envy them their access for experimentation to the resources of a large semiconductor company.
They found that by ignoring the device’s data sheet and directly connecting its output pin to its power pin, the REF5010 became equivalent to an ideal Zener diode. In this mode multiple references could be stacked in the same way as a real Zener diode, and very stable and high-precision voltage references could be created with very high voltages. They made a PCB with ten stacked REF5010s for a 100V reference, and then stacked ten of them for a 1000V reference. Leaving it for 24 hours to settle, they achieved a precision of +/- 2.5ppm, and after 3.5 months their average reading for the ten 1000V references they built was 1000.022V.
The 1000V reference would be impressive enough, but they weren’t finished. They built a series of boards holding 500 REF5010s for a 5KV reference, and stacked 20 of them to make a 100KV reference. These boards were mounted in a tower looking not unlike the Tesla coils we sometimes feature here. They note that it probably hits the record of simultaneous use of TI parts in a single device.