3-phase Jacob’s ladder

Two sparks are better than one, a sentiment that was never more blindingly illustrated than with this three-conductor Jacob’s Ladder. The build centers around three-phase power, which uses a trio of alternating current sources sharing the same frequency, but offset by 1/3 from one another. If we’re reading the schematic correctly, [Jimmy Proton] is using normal mains as a power source, then connecting three transformers and a capacitor to set up the different phases. Two of the transformers, which were pulled from microwave ovens, are wired in antiparallel, with their cores connected to each other. The third transform is connected in series on one leg of the circuit.

The video after the break starts with the satisfying hum of power, only to be outdone by the wild sparks that traverse the air gap between conductors of the ladder. After seeing the first demonstration we kind of expected something to start on fire but it looks like all is well. We’ll probably stick to a less complicated version of Jacob’s Ladder.

[http://www.youtube.com/watch?v=2w54QjtR0nc&w=470]

Comments

  1. jim says:

    This is seriously dangerous to the unskilled hacker.

    More.

  2. Oli says:

    Wow, not much of security in it : I don’t see any current limiting or whatever !

  3. BadWolf says:

    Just checked his schematics on Instruc. and it’s not three phases. He call it like that but there could have been as many phases as he wanted. Also,the third transfo is the ballast which means it’s only to preserve the first 2, no link with three phases there anymore.

    Could someone with a decent background in electric engineering verify this before I look like i’m bashing a nice looking project?

    Thanks

  4. Colin says:

    actual video

  5. minifig says:

    If this is using a standard AC outlet as a power supply, rather than the 220v-capable 4-prong outlets, then it isn’t taking 3-phase as input. That said, he wires one of the ladder wires (“leg”) to either ground or the core of the transformers. Wiring the last leg to ground shouldn’t cause it to be a three-phase system, but wiring that leg to the transformer cores instead could do something. I wouldn’t know what, though.

    In his defense, there are three wires on this Jacob’s Ladder, not two. And it still is a cool project. I just wouldn’t have referred to it as three-phase unless the original source did as well.

  6. password says:

    i just took a look . that is basically a centre tap with one ballast on one leg , which can be called 2phase with a neutral reference basically its the sam as single phase . i will however take a look at the vid later today

  7. Jorge Garcia says:

    To start, very dangerous but very cool.

    As others have already mentioned this is not using three phase power. The series transformer is used as a ballast which provides some current limiting(current stability would probably be more accurate) but nothing I would trust.

    password nailed it on the head. It’s a two phase system with respect to neutral, he achieves that by the anti-parallel wiring of the transformers.

  8. password says:

    ok i have looked at the video.One way to know if its is truly three phase is by getting 3 sparks( one for each phase) that jumps to and from each phase.
    this project is basically just taking a long spark and putting metal objects between the spark points(a wire in this case) his ladder would still work if he disconnected the middle wire but left it there , so the spark can travel from the left wire to the middle wire to the right. meaning “the neutral” wire just helps guide the spark. But it also compensates a bit because it can to on its own “transfer energy” when the load(in this case the spark gap) is not balanced( between the “two phases”). So in essence he still has a single phase system. i wonder if my prof woul let me build a true 3 phase Jacobs ladder since we have variable three phase star power outputs here that can handle gigantic load

  9. G says:

    May as well remove the talk about three-phase power in the description for this story and get rid of that link to wikipedia link too since this has nothing to do with that. I don’t think he even knows what 3-phase is. “The ground phase?” Nice.

  10. hpux735 says:

    Kinda gotta give this kid credit, in a way. He’s trying to learn EE in the most haphazard and dangerous way possible. It would be nice if he knew what 3-phase really is before he starts plugging things into the mains. Next, he’ll probably just hook it up directly to the 3-phase buss bar inside of the circuit breaker cabinet.

  11. mic says:

    “This thing pulls a LOT of amps so if you have a crappy 20A breaker then it will trip whenever you use all three phases at once but if you have a nice 30A or 60A breaker then it can handle this thing just fine, just watch out for overheating…”

    WHATTT!
    Greater than 20 amps being drawn!!!? This thing is practically a short circuit. Looks cool but there has got to be far more efficient ways of doing that. The breakers are not crappy, they just saved your house from burning down. Don’t circumvent the breakers that just saved your house… Cool but scary as hell.

  12. mjrippe says:

    “never touch anything with your bear hands while its on”

    or your human hands for that matter…

  13. Grazz256 says:

    I enjoy how he trips the breaker on the first run, he must have switched from the 20A breaker after that.

  14. Hirudinea says:

    Igor do good!

  15. Tim says:

    I wonder how much harmful UV radiation that throws off

  16. macona says:

    Like others have said, not three phase, not even close. No wonder he is pulling mass current with that cap right across the mains. You can use capacitors to phase shift (Like a PSC motor), but not like that.

    Incredibly bad design.

    At least use neon sign transformers. The secondaries are current limited. You will have to isolate the transformers as they are mid point grounded though which is usually difficult to do.

  17. BillTheWelder says:

    Seriously the only good thing that has come out of this feature is that some people know enough about electricity to have quickly figured out that the maker has no idea what he is doing and that what he has done is dangerous.

    Something that both Hackaday and Instructables should do along with other sites like them should do is vet things like this with professionals ( I’m sure that there are more than a few engineers who would love to get their name on hackaday to get exposure ) who have knowledge of these types of builds before posting them to their websites. Having seen some home made welding machines and ones that have been modified I’m dreading to see more builds show up on this site and others because the danger that comes along with modifying and or making your own welding machine goes beyond exceptional.

  18. Thomas says:

    The third transformer should act as a kind of inductance, so that phase is shifted. This would not really make it 3-phase in a 120 degree phase sense, more more like a 90 degree shift. This could give voltages of respectively 2000, 2000 and 2800 volts between the spines of the ladder.

    That the extra transformer is shorted on the primary negates the 90 degree phase shift somewhat, however.

    Still, the third transformer is a kind of phase shift device.

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