Plasma Spheres, Jacobs Ladders, and Other Things

updated very slightly 9/23/2008.

Plasma Spheres

Many of you have seen these things, which are glass spheres with an electrode inside. Sparks fly from the electrode towards the surface. If you touch the sphere or even move your hand close to it, the sparks will concentrate towards your hand.

My Plasma Sphere Page is now here!
(These things are occaisionally called "lightning globes")
(Last significant change late June 1996, minor update 5/20/2006.)

Jacobs Ladders

You have almost certainly seen these. This has two wires with an arc in between, climbing upward. When the arc reaches the top, it goes out and a new one starts at the bottom.

To find out more, see Sam Goldwasser's Jacobs Ladder Article. (New version 1.29, different file name, copied to this site 11/3/98)

You may also want to see Bill Beatty's Jacobs ladder text file.

WARNING - Jacobs ladders typically use currents around 20 to 30 milliamps, and I have seen several credible warnings that as little as 5 to 8 mA. of AC at power line frequencies can sometimes kill. Also, the arc typically generates traces of noxious ozone and nitrogen dioxide. Build, operate or troubleshoot these only at your own risk of death/injury/fires/lawsuits.

Silly Neon Lamp Tricks

At long last, finally something here! A neon lamp oscillator. This can actually make a tone come from a piezoelectric speaker without using any semiconductors. (New document 10/12/96)

A multi neon lamp flasher from, now at This document is in PDF format.

Written by Don Klipstein.

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