If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #340
Joined: Thu Mar 23 2006, 06:05PM
Location: NY
Posts: 5
Can anyone tell me what might be the best type of plastic to use for a Van de Graaff generator tube?
I'd like the plastic to be clear, however I'm not sure which type of plastic tube material will best keep the static charge from traveling down it. I'm currently looking at clear ABS, clear PVC, acrylic, butyrate and polycarbonate. It's difficult to find specs on these plastics, and even when I do, I see volume resistivity, surface resistivity, dielectric constant, etc. Which would be the proper specification to optimize?
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
Compared to voume or surface resistivity specs intrinsic to any of those plastics, the best two parameters to get right are the surface cleanliness (no finger prints etc), and the humidity (dry as a bone, static weather). (My son's school had an open evening a while ago and he went in with instructions to blow-dry the VDG, whatever the teachers said. For the first time in years they had a decent demo.)
The next parameter which does have something to do with the plastic is the surface finish. Acrylic can acquire fine surface cracks which attract moisture, so it's generally not the first choice for HV use, but a new clean specimen can be OK.
Registered Member #187
Joined: Thu Feb 16 2006, 02:54PM
Location: Central Ohio
Posts: 140
The VDG builders that I know generally use whatever they can afford. Clear acrylic is generally sought after, but it can crack if not handled properly.
The key is (as NeilThomas stated) making sure the column is very clean and dry. If cost were not such a factor, I would go for polycarbonate since it is crack resistant and lightweight. However, odds are it will not make a measurable difference in your machine's performance.
Registered Member #10
Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
My VDG only did 2 inch sparks, so I am not the person to comment really but... You need to realise that surface tracking over any nonconductive surface can be up to 3 times the spark length in air. This is one reason why insulators have a corrugated surface. it is hard to make a cheap light and structurally strong corrugated VDG support however.
Don't expect to get a spark 3 times the secondary length like with a TC in which spark growth is way above what is expected from peak voltage, more like the other way around ie 3ft high for a 1 foot spark.
Here is an ignition coil giving 3 inch sparks but the surface tracking is 9 inches on an alcohol cleaned surface.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.