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 #3781
Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701
ok so I have a plasma speaker driven a 555 timer and it was working fine but yesterday I was playing around with it and I think the fet blew? It would not strike an arc and the drain and source wires became so hot they melted... Does anyone know why this is happening?
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
It sounds like it did indeed blow. What mosfet are you using? Flyback drivers are very hard on transistors due to the high voltage spikes created on the primary. You need a good HV mosfet and a snubber to prevent the spike from destroying it.
Registered Member #3781
Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701
Alright thanks, that is what I figured, just wanted a second opinion. I was using an IRF644 no snubber though... It did last quite a while although this past week i have been driving the flyback with 24v instead of 12 and the fet did get pretty hot after a few minutes
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
Yep, the fet blew and was shorting out. Try putting a few in parallel (might need a driver). You might also try putting a 1 or 2 ohm resistor in the line to the gate to stop any ringing and keep the fet out of the grey area between off and on.
Registered Member #3781
Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701
ok it won't work :( I rebuilt the circuit, i replaced the 555 timer, I tried different mosfets, I tried different power supplies, I tried different flyback drivers, I checked and re-checked the circuit but nothing is working!?! I had it working for a month and then the fet blew and now it wont work again. The supply rails do have power becasue the fan on the heatsink spins.
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
Check the dumb stuff, I spent a whole weekend trouble shooting and then found out I had been using TL071's instead of 555's... felt like an idiot. Try replacing the 555 and FET at the same time, if one blows they might take the other with it. Are the fet's you're trying getting hot? If not then they might not be getting a signal, do you have a scope?
Registered Member #3781
Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701
Alright, yeah, I think I may have hooked up the mosfet wrong as it is not getting warm or anything when the circuit is on and there is no voltage going through the flyback... I have the Gate going to pin 3, Drain going to flyback, and Source to ground
Registered Member #3781
Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701
yes it is, and yes my 555 timer was blown ha, i didnt notice it heating up before but it is so I will check the circuit tomorrow... and I have an oscilloscope at school, but not at home
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
You should be able to check it visually with a bit of patience and a multi-meter. And be careful if you take the flyback portion to school, most people frown on voltages over 9000, and if you try to measure the voltage between the flyback primary and FET (a good thing to check for spikes) be sure the scope can handle the voltage, a 12V rail could have some really high spikes. My school doesn't even own an oscilloscope, so I'm limited to mine, which is only 20V max... woot.
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.
problems (Solved)
