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 #62119
Joined: Sun Feb 04 2018, 04:59AM
Location: Cedar Rapids, Iowa
Posts: 136
Has anyone ever used a varistor to protect the DC power supply for a Marx generator? Having just killed a laptop PC switching power supply, I am now going to build a linear transformer-based DC power supply for the Marx generator. To guard against high voltage spikes from feeding back from the Marx generator to the DC supply, I am considering adding a suitably-rated varistor to the output of the DC supply.
Does anyone think this would help? If so, what would be a good varistor maximum voltage rating for a 24 volt DC supply? I have a lot of 150 volt varistors on hand.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
A PC switching supply on hand may be old with poor insulation on the supply side windings. The failure may have resulted from the Marx generator flash setting a high voltage on the input.
How is the Marx generator grounded in your experiment area ?
Registered Member #62119
Joined: Sun Feb 04 2018, 04:59AM
Location: Cedar Rapids, Iowa
Posts: 136
radiotech wrote ...
A PC switching supply on hand may be old with poor insulation on the supply side windings. The failure may have resulted from the Marx generator flash setting a high voltage on the input.
How is the Marx generator grounded in your experiment area ?
Not grounded at all. What point on the Marx generator would I ground?
Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
The trouble with varistors is they degrade every time they get triggered - how much depends on the energy of the spike. A big fat transil might be better.
Registered Member #62119
Joined: Sun Feb 04 2018, 04:59AM
Location: Cedar Rapids, Iowa
Posts: 136
As a possible way to avoid this problem, I am considering using two 12 volt lead acid batteries from a UPS as the power supply. The two batteries would connected in series for a 24 volt DC supply. This would completely isolate the Marx generator from the power line. Hopefully any high voltage spikes won't be too hard on the batteries.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
Lead acid batteries are a good idea. However, if you decide to also float charge them while operating the Marx system, you may still have problems.
Also, vented lead acid batteries may have hydrogen out gassing, especially if old. A spark can blow the casings to bits. (and launch pieces..) An emergency light blew up and bits were found 60 feet away. The charging regulator had failed.
Registered Member #62119
Joined: Sun Feb 04 2018, 04:59AM
Location: Cedar Rapids, Iowa
Posts: 136
I am considering sealed AGM-type lead acid batteries. Two 12-volt units in series for a 24-volt power supply. Each battery rated at 5 amp-hours so there should be plenty of energy there for me to run the generator for a short while. I will not be charging the batteries while I use them. I want the generator completely isolated from the house power.
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.
Varistor for Marx generator power supply protection
