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 #1643
Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039
My DRSSTC currently features a Helical primary. It's climb height is about 5 inches, and maintains 3 inches from the secondary. As it sits, i never had issues with it flashing over to the secondary. However, I want the best out of this coil, and I see a lot of the large DRSSTCs using flat primary coils instead of helical or cone. Steve wards for example. I just want peoples suggestions on if i should keep mine as is, a Helical coil, or change it into a flat coil. Changing isnt a problem. I just have to cut out 8 new peices of acrylic that attach to my clamps that extend outward.
Let me know what you guys think.
I have had tuning issues in the past.
Primary
Thanks for your time. My last setup, a CM300 halfbridge, peaked at 7ft sparks for the power I gave it. This round, its CM300 fullbridge. I'll do proper tuning, but I want to make sure my primary is best suited for operation. Also ... I will get a better clamp for primary tap :D
Registered Member #2292
Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795
Flat hands down for any DR. There is really no reason to do a helical primary in my opinion. With a flat primary you get a coupling in and around 0.2k which is more than plenty for most DRs and it is out of the way much less likely to be hit by racing sparks and toroid to primary flash overs. And on top of all of this flat is also way easier to build.
I used a helical on a DR once, my first DR, never again....
The only time I have really needed a helical primary is with my QCW where a coupling of 0.3k and greater was needed for proper operation and the top voltage was low enough that flash overs were not a problem, <70Kv in my case.
EDIT:
Also looking at your photo tuning was not the only problem, your coupling had to be insanely high with the secondary all the way down in the helical primary.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
To my understanding, the tighter the coupling the better your coil will perform, until you reach the point that it starts flashing over because the gap between primary and secondary is too small. The flat primary doesn't have the optimum coupling coefficient, it just has about the highest coupling possible without flashovers in a high-powered coil. I think DRSSTCs would perform even better if this limitation could be overcome, perhaps by filling the coil system with oil or SF6.
I had this problem once, and rather than rebuild the primary, I rewound the bottom 2" of the secondary (which had been burnt up by the flashovers anyway) with a heavier gauge of wire.
Registered Member #2292
Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795
Steve Conner wrote ...
To my understanding, the tighter the coupling the better your coil will perform, until you reach the point that it starts flashing over because the gap between primary and secondary is too small. The flat primary doesn't have the optimum coupling coefficient, it just has about the highest coupling possible without flashovers in a high-powered coil. I think DRSSTCs would perform even better if this limitation could be overcome, perhaps by filling the coil system with oil or SF6.
I had this problem once, and rather than rebuild the primary, I rewound the bottom 2" of the secondary (which had been burnt up by the flashovers anyway) with a heavier gauge of wire.
Well there is a way to overcome this limitation turn that DR into a QCWDR and get those top volts way down.
In that case I'm all for high coupling and helical primaries!
Also Dr. Spark I almost smashed my screen thinking there was a bug on
Registered Member #2292
Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795
Destroyer of mosfets wrote ...
Well there is a way to overcome this limitation turn that DR into a QCWDR and get those top volts way down. [/quote1339168145]
What is a QCWDR?
A QCW is a DR the full name of the coil is a QCWDRSSTC. A QCW is DRSSTC with a high tank impedance and control over the current envelope. Same basic principles as a DR apply.
Registered Member #1643
Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039
Well, Is it suggested that I rise my DRSSTC secondary so its not so far deep into my helical, or is it best I just rebuild the primary flat, and adjust coupling from there. I can do either. Obviously it be easier to keep the current design, and just rise the secondary, but, If flat primaries seem to run performance better, then I maybe should just build things that way..?
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.
Medium size DRSSTC - Primary Flat or Helical
