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 #540
Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969
Tuning via spark gap? I think you mean the break rate... When you decrease the spark gap's distance, the gap will fire at a lower capacitor voltage. If you meant tuning, changing the spark gap's distance shouldn't change much. You would want to change the value of the capacitor or primary's inductance.
Registered Member #1745
Joined: Wed Oct 08 2008, 12:29AM
Location: Northen Michigan, US
Posts: 19
Myke wrote ...
Tuning via spark gap? I think you mean the break rate... When you decrease the spark gap's distance, the gap will fire at a lower capacitor voltage. If you meant tuning, changing the spark gap's distance shouldn't change much. You would want to change the value of the capacitor or primary's inductance.
Yes, you are correct with what you said. Is there a formula or anything for determining the distance the spark gap should be?
Registered Member #1739
Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261
Add a proper power filter! RF chokes + protective sparkgaps will protect your transformer from anything bad that may happen in the primary circuit, including primary strikes, gap misfiring and anything else you can think of. As for formula, you can try Pashen's curve for lower voltages. The additional protective gaps should be set up between the system ground and transformer output, filter output and around your MMC to exclude an option of MMC capacitor overvoltage. Also a good idea is to bypass the transformer low-to-high side with a small capacitor to exclude any RF between the transformer windings that may pass the RF choke.
Registered Member #1745
Joined: Wed Oct 08 2008, 12:29AM
Location: Northen Michigan, US
Posts: 19
LithiumLord wrote ...
Add a proper power filter! RF chokes + protective sparkgaps will protect your transformer from anything bad that may happen in the primary circuit, including primary strikes, gap misfiring and anything else you can think of. As for formula, you can try Pashen's curve for lower voltages. The additional protective gaps should be set up between the system ground and transformer output, filter output and around your MMC to exclude an option of MMC capacitor overvoltage. Also a good idea is to bypass the transformer low-to-high side with a small capacitor to exclude any RF between the transformer windings that may pass the RF choke.
I have been heavily debating a terry filter, and it probably would have saved my transformer in this case. Thanks everyone for the help!!!
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
Crimson Rain wrote ...
Is there a formula or anything for determining the distance the spark gap should be?
You don't need a formula for setting the spark gap. Just connect the gap to the transformer with no capacitor or primary coil and set the gap as wide as possible so that can still arc over.
The safety gap, if you have one (you should), should be set using this same method (no cap+primary). But set the safety gap just wide enough that it does not arc over.
That said, I have been using these methods on my SGTC for years (I use a 15kV 30mA xfmr) with no failures. I do not have a Terry filter. Not to say it doesn't help, I've just never needed one.
Sorry to hear about the transformer though; just look at it as an excuse to get a bigger one!
Registered Member #1745
Joined: Wed Oct 08 2008, 12:29AM
Location: Northen Michigan, US
Posts: 19
Shaun wrote ...
Crimson Rain wrote ...
Is there a formula or anything for determining the distance the spark gap should be?
You don't need a formula for setting the spark gap. Just connect the gap to the transformer with no capacitor or primary coil and set the gap as wide as possible so that can still arc over.
The safety gap, if you have one (you should), should be set using this same method (no cap+primary). But set the safety gap just wide enough that it does not arc over.
That said, I have been using these methods on my SGTC for years (I use a 15kV 30mA xfmr) with no failures. I do not have a Terry filter. Not to say it doesn't help, I've just never needed one.
Sorry to hear about the transformer though; just look at it as an excuse to get a bigger one!
Thanks for the insight on the spark gap setting! And yeah, im getting a 7500V 60mA transformer == 450 watts instead of 360
Registered Member #1535
Joined: Wed Jun 11 2008, 11:37PM
Location: Northeastern Pennsylvania - USA
Posts: 117
I smoked my first transformer about the same as you. I was a real noob. I added a Terry Filter, set the gaps properly and lived happily for many months.
I migrated to a rotary gap. It still has the Terry Filter. I smoked my second transformer by lowering the rotary speed to far. Similar to my setting the gap to far on the static setup.
The Terry Filter is a nice cushion, but it is no catch-all. I know it works/does something, because the first night I used it, I forgot to solder the mov string part of it and I saw small arcing where the leads were supposed to be soldered, on video the next day. It was passing spikes to my RF ground I assume...
My 2nd transformer probably died because the safety gap was too wide that night? I wonder if it was proper, would the transformer have survived? I stay above that lower limit on my rotaty speed now because I'm scared. I wish there was some sorta fool-proof protection... Ya right...
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.
A quick question about sgtcs
No more tuning via spark gap for me!!!
