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Musical Tesla Coils Perform Zelda
heychris writes "You've gotta love the Chicago Tribune's story on Tesla Coil hobbyists from the first sentence. 'Under a starry Saturday sky behind a Lake Zurich warehouse, three men unload a small flamethrower, electric cabling, neon-tube "light sabers," about 80 pounds of chain mail and two 7-foot devices that look like monster-movie props.' So what does one do with 1.6 million volts and a Tesla coil or two? Play 110dB music, of course."
They're more like speakers than an instrument. He's not "playing" them so much as they're just outputting a pre-programmed song. The act is just for entertainment.
"People who think they know everything are very annoying to those of us who do."-Mark Twain
There are likely only about 1,000 Tesla coil hobbyists worldwide.
There are quite a few more of us around as the Pupman mailing list http://www.pupman.com/ and the Geek Group http://www.thegeekgroup.org/ can attest.
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Because it's ubercool geekery?
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The coils are the actual sound output device. There are no speakers. There are only bolts of fantastic musical lightning.
There are dozens of videos on YouTube featuring this sort of thing, including people using such devices as guitar amplifiers.
Learning about brewing beer, by brewing beer.
I guarantee they aren't using 1.6 MW of power.
On the other hand, Tesla coils are all about the voltage.
They call it 'modulated thunder'. Thunder is just the noise produced by expanding gas heated by an electric discharge. The coils are actually being switched at several kHz, producing repeating 'thunder' at a frequency above the point where you stop hearing the individual claps, and instead hear a tone. It effectively is a low-mid range speaker.
Based on chatting with them when they did Penguicon in Michigan they use a control circuit to turn the coils on and off at a specific rate. This allows them to use the actual lightning breaks per second to generate sound. E.g. 128 breaks per second roughly equals a sound at 128 Hz.
When they were coming out here they asked us to provide 2 note MIDI files for playing. If I remember correctly the computer uses MIDI to drive the control circuitry that is fed optically (to avoid coupling to the coil itself) to the drive electronics in the coil. So not so much pre-programmed as interpreted.
Really neat technology they have put together and darned loud! I wonder if they ever built the other two notes they talked about building at Penguicon. Hearing 4 of those going in harmony would be sweet!
In this case I would not want to be the recipient of the electric bill. These are not your father's tesla coils. These are fairly low voltage very high current devices. The feed they got from the hotel at Penguicon a few years back was a 220V 50A and I remember them having an ammeter on the line to make sure they didn't exceed the rating and trip the circuit.
They run high current at lower voltage to be able to use solid state switching devices to drive the coil. No rotary spark gap here just a bunch of IGBTs and other fun silicon the size of your fist.
Two notes only. Each coil produces one note. At least that is how they were when I saw em a couple of years ago and the setup looks the same.
Sound in real life. Loud. Really freaking loud. These are 7 foot tall units putting out sparks around 7-10 feet controlled. Sound is point source to the coil it is originating from, sorta. The sorta being pretty much the area of the spark itself, so the source is wider than one would think. Highest and lowest dunno, though it had a very good audible range. The sound was a bit harsh due to the nature of how it was being generated and the noise from the bolts themselves.
All in all darned impressive. Very well done and they were very knowledgeable. I had the chance to sit down and chat with them for a little bit before they left and all I can say is "wow".
I can't speak to the rest of this - though it sounds quite dangerous - but DON'T FUCK AROUND WITH A CRT UNLESS YOU KNOW WHAT YOU ARE DOING
There's banks of capacitors in there that, if charged up, will kill you in an instant, if you're unlucky or stupid enough to bridge one. They hold about 30kV. If you want to try this, make sure you leave the TV unplugged for a few days, to drain the caps - or properly discharge it. In theory, you can ground the anode - but I'm not qualified to ensure that's safe. I can't speak for the rest of it, but it sounds fairly dangerous as well.
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