Ed is right.
A 1 inch wide pulley will only give you approx 3/4 uA charging current which
will leak back down your column (leakage current is important in VDGRF
design) and not allow the HV terminal to build up any large potential.
Also, for best performance, you need a metal not a plastic pulley, and
preferably a positive sprayed 7 kV DC power source
I use a 6" wide belt with a 24" sphere and jump to 10" width for my larger
30" and 40" spheres.
Dr. Resonance
On Sat, Sep 19, 2009 at 2:14 PM, Ed Phillips <evp@xxxxxxxxxxx> wrote:
VDG's are high voltage and I think the moderator will tolerate some traffic
on the subject. Those things are available anywhere as part of rollers to
go under things like stoves and you can probably pick up something locally
for no more than the cost of buying that thing and having it shipped. Those
are mighty small for a VDG of any proportions and I'd think you'd want to
roll your own. A lathe is of course to be desired but even mounting the
blank in a an electric drill and filing it as it spins will work pretty
well.
Ed
Ken or Doris Herrick wrote:
A little off-topic but perhaps the moderator will tolerate it. Those of us
who might contemplate making a Van de Graff generator would likely need
crowned pulleys. I note that the Surplus Center (www.surpluscenter.com)
currently offers item 1-2940, a "roller strip", at $2.95, which is purported
to contain 13 removable crowned nylon pulleys, each 3/4" diameter x 1" wide.
Ken Herrick
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