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 #4127
Joined: Fri Oct 07 2011, 05:40PM
Location:
Posts: 22
A bunch of us did a class together, building plasma balls and plasma sculptures (Instrucotr's Pieces)
We used the following circuit. I am getting reports from other classmates that they're having lots of failures. I have three of these, and haven't had any failures yet, but unlike many, I don't leave these on for long durations. Before I test mine for some hours and burn it out, I wanted to get some idea what needs to be fixed or beefed up. I'd appreciate any help and comments. ]schematic_v2ra.pdf[/file]
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
The IGBT has no overvoltage protection, I would put a cap across it (a few tens of nF). The TL494 is configured for single ended operation, which allows up to some 95% duty cycle, I would rather configure it for push pull and use one output. I would use a buffer stage or at least a PNP transistor for fast turn-off of the IGBT, the TL494 cannot sink current in this configuration and the IGBT turns off slowly. Of course the transistor may also fail of overheating, which could possibly be fixed by using a bigger heatsink or a fan.
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
We should go around the Internet and request the removal of all the flyback circuits without some form of overvoltage protection on the switching transistor...
Registered Member #4127
Joined: Fri Oct 07 2011, 05:40PM
Location:
Posts: 22
We do have a pretty hefty fan and heat sink on these. See picture.
I guess the first step would be to add a cap between the collector and emitter. What's the best way to tell if our problems may stem from the lack of a buffer stage? I think people are blowing their MOSFET or IGBTs, and not the TL494.
Lastly, there is lots of RF noise, some going back to the power supply, or going back up through the TL494's signal in (for those who are trying to modulate music). My oscilloscope is rather useless too due to the overwhelming RF noise. Is this just a fact of life, or are there good ways to isolate the noisy parts of the circuit? (Standing close to the unit, and trying to use a smartphone touchscreen is almost impossible).
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.
Can anyone spot the problem(s) in this flyback circuit?
