Warning: All test measurements were done incorrectly due to lack of experience using an oscilloscope with a floating voltage source (i.e. where neither electrode is grounded) - one electrode was always being grounded. As a result this information is useful for seeing how the device was constructed and the measurements are useful for historical reference only.
This is an attempt to duplicate one of the small testatika machines (the one in the picture below). It is a 'testbed' because not enough details are available to duplicate it -- both in terms of parts and why/how it works. So an experimental approach is taken, testing out theories and components one at a time.
Note that all grids that are facing the wires on the disk are made of aluminum whereas the wires on the disk are steel. This means that dissimilar metals are being used and are likely the source of at least some of the potential. See here for some tests with dissimilar metals.
I'm testing it component by component since there are many unknowns in how it is built. This way I may get some hints as I go along.
End of testbed 1
At this point it was decided that many changes had to be made to get rid of the disk wobble and do further experiments. As a result small machine testbed 2 was made.