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 #2909
Joined: Wed Jun 09 2010, 12:31AM
Location: fort belvoir, Va USA ( south of DC)
Posts: 145
Hello forum I am rewiring and designing my old capacitor charger, which was haphazard at best, just two transformers in series ballast by a light bulb and a 1kv bridge rectifier. No diode protection either, which was the probable couse of the deaths of my bridge rectifier. I have added and removed a few things and I wanted some opinions of others on my design any comments are vary much appreciated. Some specs: Xformers: x2 500KVA 120v to 460v put in series for about 800V-1000V Bridge rectifier: 15A 1000v Capacitors: x16 4700uf 400v set with 8 // and set in series given me 800v Here is a picture of the circuit diagram Please point out any errors (like diode direction I keep getting the cathode and anode mixed up) Here is the charger (it’s a mess but it is work in progress) And the bank
And the high current switch which I hope to replace with some of the large SCRs I have thank you for any help
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294
In my experience, coilguns have better efficiency with lower voltage. It seems that peak efficiency in most configurations is realized in the 200 to 300V range.
The only 800V coilgun I've seen built was not very impressive For all the big capacitors he uses, his projectile can't even penetrate a soda can at point-blank range (not to discredit the designer, this guy has done a lot of impressive projects).
The reason for this is magnetic saturation. Because the voltage is so high, you have a HUGE spike of current going through your coil, which results in a very intense, very short-lived magnetic field. Basically, your coil would be trying to cram all the energy into your projectile all at once. This sounds good, but it's not- your projectile can only efficiently absorb energy from a field of a certain strength before it "saturates". Wikipedia will explain this better than I can
With such a high voltage, you reach this saturation point very quickly and your projectile won't sponge up the energy, and despite your impressive capacitor collection, you'll have the output of a much weaker coilgun.
Some options, the way I see them, are:
1. Do it anyway. You'll need to use a HUGE projectile though so it can absorb as much magnetic energy as possible. 2. Just use a few of your 400V capacitors in parallel. You won't get to use all of them, because your pulse will get to be too long, and your design will suffer from suck-back. 3. Build a rail-gun? Railguns work great with high capacitance and low(er) voltage. Your collection of capacitors would be great for this. 4. Build a multi-staged gun and split the capacitors between stages. With only a few caps firing per stage, you should be able to keep your projectile further out of saturation.
Lastly, be sure to simulate your current pulse before you try firing your coilgun. With as much potential energy as your capacitors have, I fear for the continued existence of the switch your are using.
Registered Member #2909
Joined: Wed Jun 09 2010, 12:31AM
Location: fort belvoir, Va USA ( south of DC)
Posts: 145
i was thinking of a rail gun, and i whould'nt worry much about my switch, its rated for 400V 800A continously, i have dismantled it it has 1/4" copper swing arm with a .5"x1.5"x1.5" tungstan contacks and there are 3 of them as from the pic (its a three phase power switch) the thing is 50kg+., but do intend to swich to SCRs i have 3 800v 600A (8000A peak) SCRS and 3 1400v 600A (4300A peak) diodes, to hopefully replace this monster. but i may try the huge projectile idea. any suggestions on the circuit, or wiring, any erros i may have
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.
capacitor bank and charger, second opinions\ advice
