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 #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
I will re arrange the capacitor bank to be 1200V and reduce the work coil inductance. That should cut the pulse length to half and increase amplitude a lot :)
Registered Member #11591
Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556
Kizmo wrote ...
I will re arrange the capacitor bank to be 1200V and reduce the work coil inductance. That should cut the pulse length to half and increase amplitude a lot :)
1200v was (is) my goal. seems a nice balance between enough voltage to have a large dv/dt but not so much as to have complex insulation arrangements. It also comes under the rating of my 300A 1600V stud thyristor.
Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
So here are some numbers:
I reconfigured the capacitor bank from 2s8p to 4s3p Now the bank is rated for 1600V 4361µF 17mOhm ESR (capacitance and ESR were measured)
First test shot with high speed camera, 1600V 5600Joules and 192g aluminum disk.
- Measured speed 80m/s over the distance of 80cm - Kinetic energy 614J - Efficiency 10.9% - Peak current 20.3kA, current rise time about 200µs
(From other shot, but the waveform shape is same)
As you can see the current rise is now much much faster and it does show.
Interestingly i fired the 390g disk and it was travelling at 54m/s (569J kinetic, 10.1% efficiency) so this time around heavier disk was not better.
But the 390g disk did one thing: it hit the projectile stopper contraption so hard that one of the sand bags i used exploded and for a split second there was raining sand in my hobby corner... what a mess
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Do you have any pictures of your SCR setup?
Is your work coil just potted in epoxy between two pieces of wood or did you do something extra to keep it holding together for so many high power shots?
*biiiiiiing* and looking forward to the scaled up version :)
Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
Mads Barnkob wrote ...
Do you have any pictures of your SCR setup?
Is your work coil just potted in epoxy between two pieces of wood or did you do something extra to keep it holding together for so many high power shots?
*biiiiiiing* and looking forward to the scaled up version :)
Quick drawing of the current coil. So far it has stayed together ok up to 5.9kJ 20kA. Mabe 20-30 shots at full energy and i cannot find any signs of epoxy cracking.
I just ordered 12 meters of 5x30mm aluminum flat for constructing the next capacitor bank...
Registered Member #4603
Joined: Wed Apr 25 2012, 07:33PM
Location: Austria
Posts: 159
You got some serious power here! Nice! Experimenting with an ETG i noticed that the capacitance of the electrolytic capacitors decreases more and more during shooting. Could you measure the capacitance once again to do a comparison? Would be interesting to see if those big caps can handle those really high currents without wear.
Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
Made another launching coil. Old coil was getting hot after several shots at 5.6kJ. This one is wound with 20mm^2 copper cable and measures about 4.6µH. Lower inductance should give faster rise time :)
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.
High power EM projectile launcher
