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 #488
Joined: Tue Oct 24 2006, 02:19AM
Location: Maine
Posts: 8
Hello, all, I'm an Engineering physics student at the University of Maine.
Here is my first SGTC that I put together tonight, with a friend.
Parts of the system that need development: primary coil and spark gap.
Using a bank of strontium titanate ceramic caps (total capacitance 0.01µF) (not the best caps to use, as they will lose capacitance as they heat up)
NST = 12kV @ 30mA
Coil form is 4 inch, this system is not giving as good output as was originally anticipated. I'm getting around 16 inches, but then again the primary was thrown together without regard to much calculation. I am going to push for 24" which should be more than doable.
One question: Is it normal for there to be secondary arcing, to itself, on a few of the lower wrappings? I would imagine that there would be an asymmetrical voltage difference between the top and bottom of the secondary, but there would not be much voltage difference in a confined interval of about 1mm, so I'm guessing that arcing is do to a path of least resistance, where part of the secondary might be damaged and would prefer to arc through the air, along the secondary coil form to another point of damage?
Here you can see me drawing out some arcs with a Jesus stick:
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Nice coil! But i would suggest you use a better capacitor. Either your capacitor is too big, the spark gap is set too wide, or the cap has really high losses, not allowing the transformer to charge it all the way. Is it one of those CJE capacitors from ebay? Those are not good at all, and they die very quick. Get that figured out, and you should reach your goal easily!
Registered Member #1389
Joined: Thu Mar 13 2008, 12:50AM
Location: Pittsburgh, PA
Posts: 346
The arcing is normal (as far as problems go) and it is called 'racing sparks.' Raise your secondary up a few inches and the problem should go away. Otherwise you will eventually end up with a ruined secondary.
Registered Member #488
Joined: Tue Oct 24 2006, 02:19AM
Location: Maine
Posts: 8
Re tapped primary and adjusted spark gap. Now getting over 2 foot discharges. The main problem was too much primary inductance, so I killed a number or turns.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Well, 32 inches is the estimated max spark length for that input so you are doing very good! More tuning or a better capacitor or a rsg(use synchronous) will probably give you max spark length. And since you have gotten this far, why not go for more than estimated spark length?
About the racing sparks, it is the coupling that must be wrong. Raise or lower the secondary in very small increments until best spark length/no racing sparks are achieved. Be sure you do not run if it has racing sparks. It will ruin the secondary insulation, and cause carbon tracks to for which are slightly conductive, enough so to ruin the coil.
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.
My first SGTC (with video)
