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.
Hi all, sorry for introducing myself only now, but in my few previous posts I was in a hurry and didn't do it. I am an Italian coiler working since about three years (with many long stops ...) on the realization of a DRSSTC. After lots of studying and planning, I have had a very successful experience with my first coil, thanks to the unbelievable know-how that has been shared by many experienced coilers on this forum and on their personal sites.
Here are the main characteristics of my coil:
Primary: 45deg conical, 7.5 turns of 6mm (~1/4â€) copper tube, tuned on the last turn (close to the end) Secondary: 11x61cm (~4.3x24â€) on PP form, ~1670 turns of 0.35mm (AWG28) copper wire MMC: 2 strings of 5x 0.22uF/1000V caps, total 88nF/5kV (marked RS, made by Arcotronics) Bridge: 4x IXGR60N60C2D1 (Icm=300A) Driver: Steve Ward’s 2005 DRSSTC driver Resonance: 120kHz measured (JavaTC calculates 140kHz) Coupling: 0.17 (calculated with JavaTC) Power: 230V rectified Spark length: 120cm (~4’) at around 400A primary current
Recently I have updated the OCD section of the driver: I have replaced the rectifier diodes with 1N5819 and moved the burden resistor after the bridge, following the most recent Steve’s driver schematic. Unfortunately I caused an almost invisible short during soldering with the result that the OCD wasn't working when I powered on my coil. I was so anxious to test my just bought digital scope that I didn’t realize I reached the maximum burst length given by my interrupter (360 us, should correspond to 640A, 8kV on the MMC from simulations!) with the OCD led still staying off. Before the update, the OCD was limiting at around 400A. After few seconds at full power I saw the MMC enlightened by sparks! Afterwards I saw that one of the caps became fat, its capacitance dropped to 24 nF and its resistance to few Mohms. However I noticed already before this last run that the caps showed signs of stress, consisting in strange dips in the middle of the body: I knew they would have not lasted much longer, so it hasn't been a big pain.
Now I have to rebuild my MMC and have to decide among these possible options: 1. replace just the blown cap with one of the same type (I have none left, I would have to buy a new set of five from RS) 2. buy new CDE 942C caps, e.g. 0.22uF/1600V (same 2x5 configuration, same total capacitance, higher voltage, allows me to reuse the current MMC boards) 3. buy new WIMA Snubber FKP caps, 0.47uF/2000V (one string of 5 needed, total 94nF/10kV, needs me to completely rearrange the MMC)
The first option is the less expensive, but probably not the longer lasting one. The third option is attractive: it would cost less than the CDE caps, plus the WIMA Snubber FKP caps have superior performance on paper (same internal construction, 5000V/us = 2350Apk compared to 2x422 = 844Apk of the CDE caps). Moreover the max DC voltage of the MMC would be 10kV with the WIMA caps, compared to 8kV with the CDE ones; also the capacitance would be a little higher (which would help me a bit because now I reach tuning near to the end of the primary coil).
Sorry for having bothered you with this long story, I come now to my question: I see most of the coilers use CDE caps, although also the WIMA FKP series has been mentioned several times on this forum. Can you experienced guys please comment on which option should I prefer?
Thanks a lot, Maurizio
EDIT: I have ordered the WIMA S FKP caps. An additional reason for my decision is that I can build a "flexible" MMC, as I can easily change the number of caps used in series (reasonably from 3 to 5), because they have screw terminals
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.
Best option to rebuild blown MMC in a DRSSTC?
Afterwards I saw that one of the caps became fat, its capacitance dropped to 24 nF and its resistance to few Mohms. However I noticed already before this last run that the caps showed signs of stress, consisting in strange dips in the middle of the body: I knew they would have not lasted much longer, so it hasn't been a big pain.