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.
well, about that halfbridge design - i think that controllers need half bridge to work, because when they are switching, they pump upper capacitor to open upper IGBT. simple GDT could be simpler solution.
Also, those drivers (i dont know why) hate low frequencies. I tried driving fullbridge with 2xIR2111 at 50HZ and fried them both, no idea why.
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294
Turkey9 wrote ...
You should create a thread in the projects section detailing all of the design. There are not very many good threads there dealing with coilguns.
I decided not to make a project threat cus those so typically end in failure and/or lost interest. I'll write a thorough review of the design once I have something to show for it.
mattster_mac wrote ...
"Things I need help with (marked in red on the schematic) are:" Whole circuit highlighted lol!
Just thought I'd point that out, have no idea about the rest, way past my skill level. But good luck sounds like a sweet coilgun!
We'll it's all (mostly) figured out now . The complicated looking part is the IR2110 and it's really not much more complicated than wiring up a NE555. Just a few more components and one clever arrangement of transistors to make it work automatically.
dingo27 wrote ...
well, about that halfbridge design - i think that controllers need half bridge to work, because when they are switching, they pump upper capacitor to open upper IGBT. simple GDT could be simpler solution.
Also, those drivers (i dont know why) hate low frequencies. I tried driving fullbridge with 2xIR2111 at 50HZ and fried them both, no idea why.
But i might be wrong.
You're right, the controller (IR2110) is a high side driver, which means it can drive a NPN transistor whose emitter is not at ground. It does this with a bootstrap capacitor. A GDT can also be used, and is simpler if you have a readily available AC source.
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294
I can't resist sharing. 3 stages working so far, 4.52J muzzle energy and she fires as fast as you can feed her!
The other little bits are various science modules that are waiting to be fitted to the later stages. 8 total stages planned, and coming along nicely! So far, estimated efficiencies are 3.45%, 8.28%, and 9.96% on respective stages. Punches right through empty beer cans like nothing!
Registered Member #1451
Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661
DROOLLL. That's coming along nicely! Can you give us some more specs? Muzzle velocity? How are you estimating efficiency? It's been a while since I've come across a well built half bridge coilgun.
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294
Turkey9 wrote ...
DROOLLL. That's coming along nicely! Can you give us some more specs? Muzzle velocity? How are you estimating efficiency? It's been a while since I've come across a well built half bridge coilgun.
I'm trying to keep a lot of this under wraps for various reasons, but the muzzle velocity is aproaching 30m/s. Efficiency is tricky because with the equipment I have, it requires some simulation and some assumptions. I'll post another update when I get all 8 stages installed, and again when it's done (God willing).
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294
After much effort, I managed to test 7 of the 8 stages- for some reason, the 8th stage comparator shorts out the power supply whenever you apply voltage to the + input... no idea why. Also, special thanks to "Quack" (Inducktion?) in the 4HV chat for helping me figure out a dV/dt triggering issue that caused explosions last week. Anyways, here are the results of tonight's science:
A sharpened nail with 8.6J needs a cardboard box, every page of a paperback solutions manual, and a plywood plate to stop it!
Since this is a battery powered coilgun, estimating coilgun efficiency is a little different. I define coilgun efficiency as KE/total energy delivered to coil. Here’s how I did it, would appreciate input/criticisms.
1. Measure KE with scale & speed detector 2. Assume const. acceleration in coil, determine pulse width t=2*l/(v_i+v_f), where l is length of projectile 3. Input t into LTSpice simulation of circuit to determine energy delivered to coil. Simulation depends on following assumptions (asterisk denotes weak assumption): a. 6 mOhms battery internal series resistance* b. 30 mOhms series leakage resistance* c. Estimates of coil L and R from Barry’s Inductor Sim d. Transistor V_CEsat of whatever LTSpice model has e. Neglect voltage induced in coil by projectile (impedes actual coil current especially in later stages, makes est. conservative) f. Neglect dynamic increase in coil inductance as projectile passes through coil (slows actual current rise time, makes est. conservative)
Next step is to figure out what's wrong with the stage 8 trigger, then run up the bill from McMastar Carr for the body.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Sweet! Haven't seen a good coilgun on the forum in a while.
The 8th stage comparator issue sounds like the chip is latching up. Maybe you're applying a voltage outside of the supply rails, or maybe the chip is damaged from an earlier incident similar to that? I've seen CMOS op-amps do very weird things after being zapped with excessive supply voltage.
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.
New Coilgun Project
. The complicated looking part is the IR2110 and it's really not much more complicated than wiring up a NE555. Just a few more components and one clever arrangement of transistors to make it work automatically.
Haven't seen a good coilgun on the forum in a while.