Shake Sphere

A Hand held Electrostatic generator by A D Moore

In his book “Electrostatics; exploring, controlling, and using static electricity” A D Moore describes a simple electrostatic generator described as a shake sphere. Very little other information is given.

Luckily A.C.M. de Queiroz gives a simple description and picture of a built one here the operation is copied below.

Because I can never follow instructions and I always want to make my life harder, I deided to try to build a folded version. From the above it is reasonable to see that the earthed block in the centre is common so can be split, as long as its electrically re-joined.

This allows the inductors and collectors to be stacked next to each other rather than have a couple of trailing wires, and as the block is earth, then the wire joining these two blocks will be earth, much more efficient than two wires with high voltage. So I designed this.

The Collectors were 3D printed, then foiled and burnished to make then conductive. The two tubes are 200mm long and made from 25mm (OD) PVC electrical conduit. The two areas where the inductors would sit were taped. and 2 20mm steel balls were used as the charge carriers.

This was constructed and a simple test, with low humidity we could get sparks from the collectors after 30-40 rocks forward and back from the ball bearings.

For ease of use, a handle was added and a couple of insulators to keep the earthed wire away from the charge collectors.

This will produce 10mm sparks on a good day, and is an interesting demo, but practically useless for anything else