I want to build a van der Graaf machine with real welly. Not for any criminal purpose I assure you.
I want it to be a portable machine, run off 12 volt batteries.
I want to use a generated voltage to put the charges onto the belt, so I don't rely on the tribo electric effect at the roller and I can change the polarity of the final voltage. I will put the voltage onto a conducting but insulated lower roller, pulling the charges off a comb at earth voltage. I would welcome suggestions as to where to get such high voltage low current generator.
I would also welcome any design suggestions about the van der Graaf machine itself. Something from easily available materials, which will be a pleasure to build and look at... dream on!
The voltage finally reached will be the balance between the number charges carried to the upper sphere (which I can vary by changing the speed of the belt) and the rate of leakage. A more controlled voltage would be welcome, but I don't see how to achieve it.
I don't suppose such a machine is available buy, but I am open to the possibility.
Michael Bell