“Professor Kill A. Volt” Shocks Pumpkins with his Tesla Coil

jj

[JJ Dasher] is back again this year, shocking some pumpkins! (Volume warning). We featured [JJ] two years ago for his Halloween candy shocking Tesla coil. He apparently has been busy in his mad scientist laboratory doing some upgrades. This year his coil is producing 5 foot long streaming arcs!

[JJ's] Tesla coil is a uses two microwave oven transformers as a power supply. He also uses an Asynchronous Rotary Spark Gap (ASRG). As the name implies, a rotary spark gap uses a motor to turn a rotor. At certain points in the rotation, the rotor creates a small enough gap that a high voltage spark can jump across, energizing the primary coil. This idea is similar to an automotive ignition system distributor. [Pete] gives a great example of an ASRG in this video. Most ASRG based Tesla coils use the small motor to spin up the spark gap. Varying the speed of the motor creates the characteristic “motor revving” noise heard in the final arcs of the Tesla Coil.

[JJ] made things a bit more interesting by installing a couple of fluorescent bulbs inside a pumpkin near the coil. The coil lights them easily, and they glow even brighter when the pumpkin is struck. Still not satisfied, he also donned his grounded chainmail gloves and drew the arc to himself. We always love seeing people safely taking hits from massive Tesla coils, but this definitely falls under the “don’t try this at home” banner.

Comments

  1. andres says:

    i don’t think automotive distributors make direct contact. you may be confusing them with the contacts that operated the ignition coils.

  2. dx says:

    These are a lot of projects, that propose to obtain the electric power from earth electromagnetic field. The principal is easy – to make high tower and use differense in electromagnetic field tension at the top and at the bottom of this tower. The key element is electrons emitter at the top of this large conductor. Just intresting – is it possible to use this streaming arc as emitter? Probably not, because it will take more electricity, than tower produce, but may be yes. Just intresting.

    • andres says:

      an electron emitter? what about a filament like vacuum tubes used.

      • Steveo says:

        GaAs crystal in a vacuum excited with 10,000 volts should be all you need for a grade A electron beam

      • dx says:

        Ah, yes, but with this arc these devices will look like in old sci-fi movies %)

        • dx says:

          BTW. As I read, as the elementary emitter the steel rotating disk with needles at the edges, blown by air can serve, and still this effect is shown when in construction of high-rise buildings use cargo helicopters. Workers know that it is impossible to touch a steel rope on which the helicopter brings freight because at this moment the rope is energized, and as the emitter of electrons helicopter blades serve. If you in vicinities have something high with blades on a top, it is possible to try to experiment with it.

  3. Greenaum says:

    The skin effect means that sometimes people can take electricity from a Tesla coil across their bare skin, even from one hand to the other. The current only penetrates a tiny distance into the person’s body, mostly staying around the outer layer of skin.

    The higher the frequency, the thinner the “skin”, ie the less deeply the current penetrates into the conductor. This is important in things like high-voltage power transmission, RF work and other stuff.

    What I’m wondering, is, is there an easy way to work out what a safe frequency would be? Would the load of a living human change the frequency from the coil? How do you measure the frequency of a Tesla coil anyway? Or is it best to calculate and how accurate is that?

    It perhaps might not be wise to go conducting voltages through your body unprotected by chainmail, but I’ve seen it done on TV, and it’s very very impressive. Would, perhaps, a metal finger tip with a grounded wire be good enough? You could hide that better than a whole metal glove.

    Anyway, as ever, fantastic build! It’s kinda impossible to make a boring Tesla coil!

    • JJ says:

      The skin effect does not protect human skin/flesh from a tesla coil hit.
      Read this: http://amasci.com/tesla/teslafaq.html#two

      The reason people are able to take a hit from a tesla coil is because human nerves cannot fire with RF frequencies, so they don’t feel it as much as they should. However permanent nerve damage can occur.

      • wisdomseeker says:

        Thanks jj for the link! I read the whole page… Found it fascinating and learned a lot of history. Much aprreciated!

      • Greenaum says:

        Maybe it wasn’t a Tesla coil I saw then, but I’m sure I’ve seen something where a person can conduct lightning through their body, to fire out of their fingers. Man-made lightning obviously. Didn’t Tesla himself do this once or twice? Even if he did cook his bone marrow.

        • JJ says:

          I myself have taken hits from smaller coils, and there are plenty of examples of people taking hits, and sitting on top of large coils, shooting streamers from their hands. But its just not a smart thing to do. Its often painless at the time, but later you may have tingling and numbness, joint pain, muscle weakness or other issues.

  4. Bryson R. says:

    Shouldn’t the title read “[Professor Kill A. Volt] Shocks Pumpkins with his Tesla Coil”?

  5. JJ says:

    Just an FYI about the safety (or lack of) of not wearing a full Faraday suit with a coil this size. @2:18 in the video you can see a streamer strike my left wrist. You cant see it, but a streamer brushed very close to my cheek on that strike and gave me a stern warning. It wasn’t a direct hit, but I definitely felt it. This is why I pull back. I should of kept both of my arms in front of me.

    • Koplin says:

      Just about becomes toast, says he should have kept his hands in front of himself. You sir are a MAD SCANTEST. I love it! I just wont let my kids repeat it :P

    • Adam Fabio says:

      I thought something had happened there – I wasn’t sure if the streamer just had snuck above your glove or hit you elsewhere. Amazing that the streamer had already jumped back to your right wrist before you even had time to react.

    • Greenaum says:

      You might benefit from putting some sort of wire or chain over your chest, to short across your heart in case something like this happens. A good reason to get your nipples pierced.

  6. bthy says:

    maybe he should mow his lawn once in a while ..

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