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 #63
Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425
You wouldn't believe the crap I've gotten away with using for gate-driver transformers. Any time you open up monitors or junk, get those sidecutters out, and snip snip snip! You'll find cores around any of the EHT, line/neutral, grounds, interconnects. Toroids, sleeves, binocular cores -- they're all suitable!
After a few bits of equipment you'll realize most of the assemblies use the exact same size suppression cores around all those wires, and you'll have enough to be able to standardize around them for your projects. Grab a MOSFET, a driver, and a handful of known cores and try them out.
I'm not sure why core selection is always a scary issue -- this is totally unscientific, but if it's grey and you can fit wire through it, your core is probably fine for use as a GDT. Or I have been extremely lucky with junk cores over several years.
Registered Member #2481
Joined: Mon Nov 23 2009, 03:07PM
Location: ITALY
Posts: 134
I have just wound a couple of GDTs on Epcos N30 core (32mm diameter). With 12 turns I obtained about 750uH of inductance (as expected) and a total leakage of about 0.55uH. Magnetising inductance does not vary up to 300kHz and the real part of the impedance remains very low indicating low core losses (I used an Agilent precision RLC bridge). So, I suppose that N30 material should work for this application up to few hundreds of kHz.
Registered Member #91
Joined: Thu Feb 09 2006, 03:03PM
Location: The Netherlands
Posts: 45
Luca: thanks, that is good to hear.
Blackplasma: I don't think this is a scary issue at all - I'm just trying to make an informed decision instead of just going with trial & error like usual
Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
If you want to pull a potential GDT core for operation up to 500kHz from an old appliance then go for one of the following:
1. An un-gapped core set from a ferrite power transformer in a SMPS. (Practically any Mn/Zn power grade ferrite will work.) Clamp the cores together well to eliminate any air gap!
2. A common-mode suppression choke used to reduce conducted emissions from SMPS back into the mains line. (Most of these are high permeability Mn/Zn, and not terribly lossy until you get up into the tens of Mhz.)
If you want to buy a core specifically for the GDT application then the choice is easy. Go for a high permeability Mn/Zn grade (3Cxx part number) in a toroid shape. Any power grade ferrite will work fine:
If you want a GDT for operation in the 1's to 10's of MHz then you need a Ni/Zn ferrite material. Mn/Zn gets lossy at these frequencies. Ni/Zn has part numbers starting 4Cxx 4Dxx etc if I remember correctly?
Registered Member #2161
Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247
Luca wrote ...
I have just wound a couple of GDTs on Epcos N30 core (32mm diameter). With 12 turns I obtained about 750uH of inductance (as expected) and a total leakage of about 0.55uH. Magnetising inductance does not vary up to 300kHz and the real part of the impedance remains very low indicating low core losses (I used an Agilent precision RLC bridge). So, I suppose that N30 material should work for this application up to few hundreds of kHz.
Regards,
Luca
I have also had good experience with N30, in fact had it running in a 1 MHz class-e SSTC, main problem was making the GDT fast enough, otherwise the core held up very well.
Registered Member #2315
Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161
GeordieBoy wrote ...
2. A common-mode suppression choke used to reduce conducted emissions from SMPS back into the mains line. (Most of these are high permeability Mn/Zn, and not terribly lossy until you get up into the tens of Mhz.)
-Richie,
are these torroid core "covered" in white plastic(or such)? and has 2 windings (Live/Neutral)
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.
Gate drive transformer core selection
