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 #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
Be sure not to use your "good" meter. Go buy the cheap 5 dollar volt meter for this experiment. Ive blown up too many "good" meters (a nice wavetek once ) from using them around tesla coils and marx generators.
What is the gap spacing of your rotary? I always had to make my gap spacing at tight as possible for best performance from my old 15kV 100mA system. I think i usually kept the electrodes within 1/16", but closer if i could manage it. If you are using tungsten electrodes, be sure to have some sort of containment around the thing incase they collide and shear. My gap used a wimpy little synchronous motor that i accidentally stopped the rotor with my hand and didnt regret it *too* much . So my gap was relatively harmless if the electrodes did collide. I was also running 1800RPM.
Anyway, i sorta suspect the GFI is acting funny. Either that or you have a power arc somewhere before the terry filter perhaps, and by turning the variac down you quench this arc allowing power to go back to the primary capacitor again.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
I find that moving-coil meters are the best around TCs and other eht-sparky-things. Also has the advantage of no batteries required, with the drawback that (say) 20 kV x 50 uA is 1W, ok for a TC but not lower power devices.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
As far as my voltmeter that I will construct I will use a $5-10 simpson panel meter. I agree that using anything better puts it at risk of destruction.
My rotary gap is 1800rpm on 4" flywheel with 4 tungsten electrodes. They are about 1/16" of an inch. If I put them any closer I fear they will hit from thermal expansion during use.
I am hoping to find another nst 15kv/60ma without the gfi.
EDIT: Until I start swapping componets I won't know the real answer, but the person who sold me the bleeder resistor for my capacitor thinks the voltage tolerance is 30kv. this would coincide with the voltage the capacitors were probably seeing when they stopped working.
Registered Member #135
Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
One thing I think bares mentioning is that on a non GFCI NST you have a true midpoint ground.
On a GFCI NST you do not have a true midpoint ground. The midpoint is raised about 60V above 0 because of the GFCI triggering circuit. You can test it if you like. The midpoint is plainly raised above case ground by a small ceramic support, and in the spec. sheet they explicitly tell you not to ground this to case ground.
IF you have the non GFCI NST (A) midpoint grounded to your Terry Filter, and you have GFCI NST (B) to a separate Terry Filter using its raised midpoint 'hot' grounded, A will cause a current loop with B if your grounds are shared.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
I don't have them both grounded to the filter. The midpoint of the filter literally goes to the ground. Each ground lug on the NST are connected to mains ground. I am in the works of getting a second no GFI unit.
Registered Member #160
Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938
I'd like to bet on core saturation and phase shifting. It only happens once you go up past a certain point, and it doesn't reset until you bring the voltage back down to zero. Is the current still high when it happens?
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Problem solved: I disconnected the ground to the NSTs that I had in parallel. One is center balanced while the other is off by 60v (GFI unit). I also used a bleeder resistor on my capacitor with a voltage rating of 31KV instead of 15kv. These two changes now allow me to crank up the primary voltage to 120v without any problem.
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.
First light. Almost perfect and need some help
) from using them around tesla coils and marx generators. 
. So my gap was relatively harmless if the electrodes did collide. I was also running 1800RPM.
