oneTesla electrifies Maker Faire NY 2013

onetesla

Throughout the maker pavilion, the siren song of a musical Tesla coil could be heard. Those who followed their ears found themselves at the oneTesla booth. OneTesla is a hobby Tesla coil, with the added twist of polyphonic MIDI input.

Started by three MIT students, oneTesla had a successful Kickstarter campaign last year. Like many kickstarters, they are a bit behind in the shipping department. They are shipping out their third run of kits to backers now. The group had a small number of oneTesla coils for sale at the show, which appeared to have sold out by midday Sunday.

The actual process of generating sound with a Tesla coil is fascinating. All Tesla coils are resonant at high frequency. In oneTesla’s case, this is 220kHz. Human hearing ends around 20kHz, so this is well beyond the range of perception. Since the coil is locked in at this frequency, the power to the coil is modulated at the desired sound frequency. Playing an A note for example, would mean modulating the coil at 440Hz.

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Homebuilt 30kV High Voltage Power Supply

If you have need for 30,000 volts to launch your ionocraft (lifter) or power other DIY projects then shuttle over to RimstarOrg’s YouTube channel and checkout [Steven Dufresne’s] homebuilt 30kV power supply. The construction details that [Steven] includes in his videos are always amazing, especially for visual learners. If you prefer text over video he was kind enough to share a schematic and full write up at rimstar.org.

The power supply can be configured for 1.2kV – 4.6kV or 4kV – 30kV at the output while requiring 0-24V DC at the input. In the video [Steven] tries two power supplies. His homemade DC bench power supply at 8V and 2.5A and also a laptop power supply rated at 20V 1.8A DC. A couple of common 2N3055 power transistors, proper wattage resistors, a flyback transformer and a high voltage tripler is about all you’ll need to scrounge up. The flyback transformer can be found in old CRT type televisions, and he does go into details on rewinding the primary for this build. The high voltage tripler [Steven] references might be a bit harder to source. He lists a few alternates for the tripler but even those are scarce: NTE 521, Siemens 76-1 N094, 1895-641-045. There are lots of voltage multiplier details in the wild, but keep in mind this tripler needs to operate up to 30kV.

Join us after the break to watch the video and for a little advice from Mr. Safety.

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Making S’mores with 50,000 Volts

Cooking a Marshmallow with HV

[Skyy] sent us a video of him cooking s’mores with an electric arc. He’s using a flyback transformer with a zero voltage switching (ZVS) driver. This produces about 50 kV, which is more than enough to toast the marshmallow.

ZVS is a technique that triggers the semiconductor switches when they have zero voltage across them. This ensures that there’s minimal heat created by the switches, since they are not interrupting any current at the time they are toggled. ZVS is also used in lighting dimmers to switch off power without creating interference.

If you’re interested in the details, there’s a great tutorial on building the driver. If you’re interested in learning how it works, check out this simulation video.

[Skyy] admits that his setup isn’t terribly safe since it uses a breadboard, which isn’t rated for the high voltages and currents. Keep in mind that these circuits could kill you. After the break, watch a marshmallow fry in a 50 kV arc.

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Taking picture of exploding wire

wire

[Patrick] didn’t just want his name in lights. He wanted his name in glowing plasma explosions, made by sending thousands of volts through a very thin wire.

This project is an experiment in capturing high speed images of exploding wires. [Patrick] wanted to know if he could shape wires in such a way that they would explode into letters of plasma. Of course, photographic proof of this would be needed, and would make for an awesome logo in any event.

To get pictures of wire turning into plasma, [Patrick] first needed to construct the necessary electronics. A simple spark gap was constructed on a large plastic cutting board – an excellent high voltage insulator. The huge capacitors are charged with a pair of high voltage transformers, and the entire assembly is triggered with an optocoupler and a very beefy SCR.

Even though [Patrick] designed the system for a low propagation delay, there was still the matter of capturing an exploding wire on film. The camera delay varied by about 120μs, but with a really great camera trigger, [Patrick] eventually got some impressive pictures.

After getting the electronics and photography portion of the build down, [Patrick] turned to making letters out of expanding plasma. Simply shaping the wire into a letter shape before vaporizing it had no effect, so he turned to 3D printed channels to contain the plasma. After a few attempts, this actually worked, allowing him to form the letters L, U, and X in an expanding ball of vaporized wire.

Wireless light bulbs with a Slayer exciter

slayer rocksWhile playing chiptunes, creating lightning, and illuminating fluorescent tubes with a homebrew Tesla coil is awesome, they’re not exactly the safest electrical devices around, and certainly aren’t easy or cheap to build. There’s another option open if you’d like to play with strong electromagnetic fields; it’s called the Slayer exciter and is simple enough to light a few fluorescent bulbs wirelessly off a pair of 9 Volt batteries.

The circuit for the Slayer exciter is extremely simple – just a single power transistor, a few diodes, and a couple of resistors. The real power for this build comes from the custom-wound transformer made from more than 100 feet of magnet wire. After plugging the driver circuit into the transformer’s primary winding and connecting a metal ball (in this case a wooden ball covered in aluminum foil), it’s possible to light up a four Watt fluorescent tube with a pair of 9 Volts.

You can check out a video of the Slayer exciter after the break.

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Modulator box connects iPod to Tesla coil

tesla-coil-modulator

This pass through audio modulator lets you playback stereo audio on two Tesla coils. But don’t fret, you can just use mono files if you only have one coil on hand. On one side there are inputs that connect to the audio source. The other side drives the Tesla coil, switching it on and off based on the relationship between a reference voltage and the audio signal. As you can hear in the video after the break this sounds great as long as you have the right kind of source audio.

The song played in that clip is the Duke Nukem 3D theme. [Daniel] started with a MIDI file and removed the chimes and drums to make the playback a little cleaner. The demo uses just one coil because the other was destroyed during testing when feedback between the two became a problem.

For some reason this reminds us of that singing Tesla coil hat. If you’re already on our mailing list (sign up in the sidebar) you know we’re getting pretty close to unveiling our own awesome Tesla coil project. It doesn’t sing… yet.

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Home built stun baton turns you into a cop from Demolition Man

home-built-stun-baton

It seems much like a cattle prod, but [Pode Coet] definitely had people in mind when he built this stun baton. It’s not for the faint of heart — especially since a wrong move could stop your ticker cold. But the design and fabrication are top-notch, and he didn’t hold back when it comes to build images and details.

The enclosure is a hunk of PCV pipe with a cap on each end. The business end includes two electrodes separated by a 10mm air gap. The spark has no trouble jumping across that gap, and if you get it close enough to the victim it’ll use their body as a path of least resistance. The butt end of the baton features the charging port which takes 5VDC power and a pair of LEDs for feedback. This power port feeds a charger stored within to top off the Lithium cell which itself only puts out about 3.8V. This potential is fed into a boost circuit to ramp up to 16V before feeding a Royer circuit which jumps it up to 900V. That is connected to the final stage which gets it to the target of 10kV!

You can see and hear a demonstration of the baton in the clip after the break. To bad [Caleb] wasn’t around to take the thing for a proper test drive.

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