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 #1467
Joined: Sun May 04 2008, 11:58PM
Location:
Posts: 2
first off, I used to be a member here. A few years back, i built a decently powerful coilgun for a school project. Powered by 3 450V 2400uf capacitors in parallel with a modified disposable camera for a charger (charges very slowly, but ROF was not a concern), it was more than powerful enough to break things, and was not intended to be fired at full power for the demonstration. I now have another opportunity to use it for school credit, and when i took it out of storage, everything was good except for my trigger transistor (scavenged from one of the disposable cameras), which was physically damaged in transport. So I need a new trigger, but since I havent even looked at the stuff in a few years, i am sad to say that i entirely forgot most of what I knew.
So what I am asking is, is an SCR a type of transistor? what do I need to look for when buying SCRs? i saw some thyristors with high voltage ratings and pretty hefty current ratings, and if I stacked those like i did with MOSFETs in the speed controls of RC cars, those should be all i need, right? (link to one of the auctions only a 55A, but is this the right direction? I was thinking I would stack 3 or 4 of them.
EDIT: I am looking at the teccor SK040R. they are pretty cheap, and im probably gonna buy a bag of 20.
Registered Member #1451
Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661
Were you using a transistor from a disposable camera to directly discharge the capacitors in your coil? If so i would like to know what kind of camera that was! With that much energy in your cap bank you would need a very heft transistor.
The scr is a great way to go. It is basically an electrically controlled normally open switch. When you send a signal to the trigger lead the scr is conductive between the anode and cathode. Once the scr has been triggered it will continue to conduct until the capacitor is completely discharged. With scr's you really only need to know the peak surge current rating. A 55a scr can be rated for a surge of a few hundered ampers. Also you can stack scr's. Just parallel them with the anodes cathodes and gates hooked together. I use paralleled scrs and it works great.
Registered Member #1467
Joined: Sun May 04 2008, 11:58PM
Location:
Posts: 2
the trigger i was using before came out of the camera's flash circuit. it wasnt a disposable, asi had thought it was, but instead one of those polaroid izone cameras with the stickyfilm (basically a ploaroid that only developed at 35mm negative sizes, which also happened to be stickers). The board from the camera has labels next to the components, one of which was labeled "SCR", a TO-220 package component with the lettering "SCR2146" on it. so i guess i did have an SCR before.
im getting a bag of the teccors, and some more capacitors. my physics teacher is encouraging me to go for maximum power, unlike my other teacher who wanted our demos to be safe. stacking shouldnt be hard, especially with big TO-220's, as opposed to the tiny mosfets in an xmod (si4562dy's if i remember correctly).
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.
need help (trigger switching questions)
