A Scary Powerful Jacob’s Ladder

What to do with an extremely high voltage transformer and power supply… what to do…  what to do… Short it out Jacob’s Ladder style of course! Fresh from [Gristronics], a team of hackers had the opportunity to play around with a 11,000V transformer… and some copper pipe.

It’s 2.5m tall (just over 8′) and produces an awe-inspiring electrical arc. The transformer takes in 240V and spits out 11,000V. To help stabilize it, they’re even using some microwave oven capacitors to act as a ballast. The transformer is affectionately named “Betsy”. They even have a giant contactor (think relay with steroids) to act as the main switch.

During the initial setup, they noticed it wasn’t working very well, so they setup a camera to record at 240fps to see what was going on — turns out the coils were shorting to each other. After fixing the insulation, they got it working consistently — and holy cow is that a big arc.

If you watch to the end, they even show off some close up images of the copper pipe — pretty cool to see the damage caused by the electricity in a close-up.

[Thanks for the tip Patrick!]

22 thoughts on “A Scary Powerful Jacob’s Ladder

    1. That’s probably because it is harder to geht these parts than those for the wifi controller.

      Anyway, it would nice to see both projects put together – ‘wifi controlled scary powerful jacobs ladder’ :D

        1. You know… I too have access to a pole pig that I’ve used as a jacob’s ladder before. I also just received an ESP8266 and have been looking for something to do with it. Maybe I can throw something together by this Friday…

  1. Seems to have a problem starting – the trick is to add a third electrode at the bottom between the main ones, connected via a resistor to one electrode. An initial arc forms across this small gap to the resistor, then the reduced resistance of this arc becomes much less than that of the resistor, so a second arc forms to complete the circuit.

    1. This is a very cool idea. I always just tried to space the electrodes in such a way that they would self-start at the bottom. This was easy enough when using my 7.5kV sign transformer, but much more difficult when dealing with a 2kV MOT.
      Thanks for the tip!

    1. Agreed. The transformers are also vastly oversized.

      I built Jacobs ladders using old 60Hz neon sign transformers. I found that 15kv was about the minimum, and 25kv worked quite well. The angle between the pipes can be larger, and the arc will self-start at the bottom. These transformers are roughly the size of a loaf of bread, run on 120vac, and rated at 10 to 30ma or so. They are current limited (by a magnetic shunt, like a microwave oven transformer), which automatically controls the arc and avoids tripping the input breaker.

      WATCH OUT when working with these things! They can be EXTREMELY DANGEROUS! They can also result in knocks on the door from people who are very angry about interference with radio and electronics!

  2. Oh and another tip – adding a small amount of capacitance (100-200pf) across a NST powered jacobs ladder makes it sound a lot more loud and raspy!
    Just don’t go overboard and get anywhere near LC resonance at line frequency as that will kill the secondary.

  3. A local electric utility gave our National Guard unit a lesson on safety about 3 decades ago. They used a pole pig wired up in reverse such as this. Using an insulated rod (of course!) connected to a cable on one of the terminals, he was drawing arcs longer than 3 feet.

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