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 #803
Joined: Fri May 25 2007, 01:58AM
Location:
Posts: 5
Hi, I just built my first coilgun using a flash circuit from a camera. Not having the time to make a good coil myself (I did this as an in school project), I used an entire roll of 22 gauge magnet wire as my coil. The metal rod I am using (about 6cm long and 5mm in diameter) goes only about 3 feet, but I have read that it should be going much further. The circuit uses a 330v capacitor. I was thinking this was because I didn't have enough power for the coil, but then again I don't know very much beyond the basic idea of how to make a CG work. Am I right, or is it somethng else, or am I getting normal performance?
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
When the pulse is long it is not over when the projectile passes the middle of the coil and the projectile will be slowed down.
Calculate the energy stored in the capacitor and the energy transferred to the projectile, that way you can find the efficiency and can easily track your progress. It also makes it simple to compare with other peoples results.
Thats a definition question but I built a bank of 10 camera flash caps and it shot a bb through a can and clock ed with a compensated sound trap at 63 m/s . my coil was calculated and I used a SCR and a diode across the coil. Here is a good site with calculators on coils. http://www.coilgun.info/mark2/rlcsim.htm http://www.coilgun.info/mark2/inductorsim.htm
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
My first coil gun was mounted in a pencil box with nice little charge/on-off/fire switches. The similarity to KillerRabbitt's coil is I also used a roll of magwire as my coil, but it was 16 ga. A .75" ball bearing fit perfectly, and with a bank of 8 photoflash caps the ball woud go like 6 feet up. It was great as a demonstration, in that it was not dangerous, and totally silent. I don't know how that ever survived as long as it did, with no diode across the coil, not even an SCR, just a switch in series with the cap bank.
As far as the right size coil for a single photoflash cap, I'd say pretty d*m* small, alot smaller than a full roll of magwire. The best way is to experiment. Do some ballpark calculations, then wire it up.
Registered Member #32
Joined: Sat Feb 04 2006, 08:58AM
Location: Australia
Posts: 549
I found that for a single 330V, 100uF cap from a disposable camera with my first CGs, a sewing machine bobbin full of .25mm magnet wire worked very nicely. Try to get a plastic bobbin (though I still managed to get a metal bobbin to work to ~2% efficiency).
For this low power, I think thin wire is best for highest density.
A bobbin is on the order of a cm wide and two in diameter.
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.
Noob question about coils (first CG just built)
