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 #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
The distance is small and there are sharp corners. I guess something as 10 kV/cm, or 600 V total in this case (2 gaps with 300 V in each). But 300 V is the limit of Paschen's law, so the approximation may fail and the breakdown voltage can be higher. You can verify by placing a ball spark gap in parallel and adjusting the distance so the spark goes through the ball gap. Then use the formula.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Antonio wrote ...
The distance is small and there are sharp corners. I guess something as 10 kV/cm, or 9 kV total in this case. You can verify by placing a ball spark gap in parallel and adjusting the distance so the spark goes through the ball gap. Then use the formula
YES ! prescisley what i do with my lifter gap, between the sharp wire and broad round foil edge...
Registered Member #3343
Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311
Hi Patric; Yes, the litle tiles are indexable tung carbite cutting bits for lathe or milling machine. I got several from the scrap box, no sharp enough for precise cuts. As spark gap the bits have long life. Regards
May I suggest you make a Excel table, cut and paste te Antonio formula, such way you can get a table or grapic of the V breakdown ?
Registered Member #3343
Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311
Hi Antonio !
Thanks for the advice. As per your info, using the grad 10kV/cm or 1kV/mm, each 0.3mm gap breakdow may be 300V Two gaps in series results in 600V. By the way, for the range of brakdown of 4kV, wich ball diametrer do you suggest ? Regards
Registered Member #3343
Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311
Antonio :
Large diameter tungsteniun rod sometimes are difficult to get, and $$
One time (1969) I have used concret drill bits tipped with tung carbite (widia) to make spark gaps. It was a emergency repair for a TIG machine. (Withe Martins)...
Do you have any suggetion how I can evaluate the resistance during the discharge of my spark gap ? the gap is 2x 0,3mm , the voltage 1 to 4kV, the discharge current 50-200A. Other parameters are: the cap is 0.001uF, the inductance 2-5uH .
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
Newton Brawn wrote ...
Hi Antonio !
Thanks for the advice. As per your info, using the grad 10kV/cm or 1kV/mm, each 0.3mm gap breakdow may be 300V Two gaps in series results in 600V. By the way, for the range of brakdown of 4kV, wich ball diametrer do you suggest ? Regards
Oops. I read 3 mm and imagined to see 3 gaps instead of 2. Answer updated. I don't know how to estimate the resistance of a spark gap. Direct measurements are tricky. In principle if you can measure simultaneously the voltage and the current in the gap you can obtain a curve current x voltage, and from it interpolate an equivalent linear resistance. The result probably depends on the temperature.
You can try small ball bearings, but voltages below a few kV are difficult to measure in this way due to the small gap distance (5mm spheres at 1 mm spark at 2.6 kV). Don't let the >100 A current pass through the measurement gap. Add a large resistance in series and adjust the distance so the ball gap just start to spark along with the main gap.
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 question about spark-gaps...
