High-Voltage Fractals

Int 1777, Georg Lichtenberg found that discharging high voltage on an insulating surface covered with a powder, a fractal-like image appears, sometimes known as a lightning tree. Incidentally, this is a crude form of xerography, the principle that lets copiers and laser printers operate.

[PaulGetson] had a high voltage power source from his Jacob’s ladder experiments and decide to see if he could create Lichtenberg figures. Turns out, he could.

If you have a source of high voltage, the rest of the project is pretty simple. A piece of plywood serves as the insulator and baking soda crystals cause the top layer of wood to be more conductive. Adhesive in the plywood, however, prevents the solution from soaking to the core of the board.

Another interesting trick is the use of mini cups as high voltage insulators. These are readily available and inexpensive. It is a different high voltage setup, but you can see a similar experiment on the video below.

We’ve covered these odd figures before. If you want to know more about handling high voltage, we’ve talked about that, too.


31 thoughts on “High-Voltage Fractals

  1. In the linked article he is using a Flyback transformer (20-100Watts) and he is holding a wire that looks like it’s rating is no higher than about 500Volts.

    The video shows a Microwave Output Transformer MOT (1500-2500Watts).

    Please don’t think for a moment that you can use flimsy wire with a MOT. A LOPT may kill you or it may not. A MOT *will certainly* kill you.

    1. It isn’t. The description at the beginning has dust being fused by a spark, which is remotely like the toner fused by a heat bar after being picked up on a drum by electrostatics and transferred to paper. Sort of. Someone gave someone else a really weak analogy, who gave it to the next person ….

    2. Making patterns in powder using some form of energy is central to how a Xerox works. Once you see this working the questions become: how can I control the pattern to make text (laser beam)? And how can I make that useful/permanent (transfer to paper and fuse)? Granted, it is to Xerox what a moldy orange is to modern antibiotics, but still.

      1. A bit vague for my liking lol. The power transfer in a laser printer is a heater and the image medium is a laser. The only use for the electrostatic charge (not current – just a charge) is to transfer the toner.

        It shows in the size of the HV step-up transformer. Here we have a ~40Watt LOPT or a ~1800W MOT as compared to a milli-watt step-up transformer in a LASER printer.

        Thanks for your response. I thought I had completely missed something.

    1. Dendrites were an everyday thing when I used to dissect CPUs for Motorola. In addition, in some of the space systems I’ve worked on we had a lot of problem with dendritic growth, especially with solder joints, one reason we still prefer leaded solder for those applications.

  2. I like to imagine that this effect was discovered by Georg when hanging out with his friends, arcing electricity near random things to see if they could discover something cool looking (OK guys, that fine powder thing wasn’t bad — now bring me a watermelon!)

    The xerography reference — correct or not — seems to exist on the Wikipedia page about him: https://en.wikipedia.org/wiki/Georg_Christoph_Lichtenberg

    I would argue that his bigger contribution to the xerographic industry was his proposal to standardize paper sizes which later became ISO 216. Well, except in North America. We’re stuck with weird paper sizes.

  3. I spent a while making these on turned wooden vases. There is a fine line between how much solution is applied and how they turn out. I used a neon sign transformer. Too much conductivity, nothing happens, damp rather than wet works best.

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