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 #4367
Joined: Thu Jan 26 2012, 07:54PM
Location: NE Hampshire UK
Posts: 16
I built myself a Leyden jar over the last 2 days. It's a spaghetti container from Asda's for £3.75 or so. 3M Ali tape from Lidl £2 a roll. Orfcut of welder cable, bit of 20mm electrical conduit, bit of 15mm copper pipe, all out of the scrap box, and 32mm cabinet knob from Screwfix £3.79 for two in a bag. Several yards of duct-tape over the outside to protect the foil. I bought two spag-jars, intending to make a pair. They are polystyrene, so I don't know how well they'll work. if it doesn't, then the other one will get used for spaghetti. Why the thick cable says you? To get thicker fatter sparks, you need bigger currents. This cable keeps the ESR down, so currents of many tens of amps are possible, even if only for a fraction of a microsecond. The individual strands are distributed over the outer surface of the thing to suck as much current as possible. Dimensions: 11" x 3,3/4". Both foils stop 5" from the top, so flash-over distance = 10" Testing is the usual affair, balance everything on wobbly bits of wood and rolls of tape, experiment with distances and gaps etc. Testing today is using the negative unit because it was nearest. At some stage I'll put a video on the tube. It is loud, and probably V - dangerous. (keeps one hand in pocket all the time when powered up due to dodgy ticker)
Curious effect happens when discharging the top sphere using the earth-wand/globe, I took a screen-shot from a slowed-down video; it shows streamers going up the inside and outside of the container. Any suggestions to cause/reason?
Registered Member #4367
Joined: Thu Jan 26 2012, 07:54PM
Location: NE Hampshire UK
Posts: 16
Now I have built 2 Leyden jars, Ive had a chance to play with the VDGs as a pair. With the increased capacity available at each top electrode I have now nearly achieved my original objective. The sparks are now nearer to 1 MV than they were before. Measure spark-gap is 300 mm, which I reckon is as good as a mega-volt! Once I have done the savarin/bundt-tin mod I'll be there. Have a look at my latest post, see what you think:
Registered Member #4367
Joined: Thu Jan 26 2012, 07:54PM
Location: NE Hampshire UK
Posts: 16
Yep, "gazing globes". They were on sale in Sainsbury's a few years ago for £25 each. As soon as I saw them, they were identified as Top electrodes/air capacitors. The sensible public refused to pay for such a silly affectation, so they dropped the price to a tenner each, and I grabbed two 12" plus one 10", for the 'bargin' price if £20 to you sir, discount for quantity. Most of the bits have been lurking in my "future projects drawer" until ready for construction. The Leiden jars are beginning to leak and track now; Polystyrene struggles to withstand 450kV across 2mm. I'll give them a wipe-down with IPA and see. Next project is a 1 nF condenser to hang between the globes. 8" PVC sewer-pipe is my first choice for the experiment; with 6mm wall thickness it should withstand over 1 MV for a long enough to make some big fat sparks. Just got to contact someone on a big building/construction site and wave a tenner!
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.
Dual Van de Graaff Generator
