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 #697
Joined: Thu May 10 2007, 12:28PM
Location: Australia
Posts: 22
Hi, I've constructed the ZVC flyback driver circuit from the hvwiki. For me this was a relatively ambitious 'project' (if you consider a few hours work to be a project) being far higher powered than anything I've made so far.
It uses two IRF540N mosfets and is powered by the +12v rail of a computer PSU (10A).
Running it at the minimum recommended voltage certainly seems to make the output suffer. Arcs start at 1-2mm and can be drawn to about 1 inch max. However the arcs are of course, incredibly hot and quickly melts/vapourizes any electrode less than 1mm thick.
Will doubling the input voltage roughly double the output voltage and thus distance I can draw arcs on the output?
Could anyone recommend a good way to power this circuit at more than 12v. I tried connecting the PSU and a car battery recharger in series for a while before realising it was a bad idea and not worth it. The mosfets can only handle up to 24v yet even that is hard to supply at 10A or more without buying a lab power supply which would cost me some $300+ at my local electronics store.
A note on the primary: Originally it was just 5+5 however I later rewound the primary and added the two three turn coils. I noted no difference in the output (though I have no way to measure it reliably). I know the three turn coils should be *over* the five turn coils however there isn't enough room between the black flyback chassis and the core itself to have two layers of wire.
Any tips on how to get longer arcs are welcome, as well as other comments and/or design criticisms.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Edit> I've re-read your post and now know where the additional 3+3 turns come from however the circuit should operate fine with 5+5 turns up to some 40V (with proper MOSFETs)... Try to wind a bigger inductor, your one seems a bit too small to me. Also putting larger "spacers" in the core sometimes improves performance. How big is your resonant capacitor?
Registered Member #528
Joined: Fri Feb 16 2007, 10:32PM
Location: Warsaw, Poland
Posts: 166
Is it possible to achieve 100-120 DCV from rewounded MOT? And what's in general voltage output with one turn secondary coil? I have there a ~0.5kW MOT bought for 10$ and I'm going to use it for supplying ZVS driver. I will remove utterly secondary wiring, so I'll have a lot of space for own secondary winding. And I'm a 230V user.
Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
It varies from MOT to MOT, but from 0.5V to 1.5V is the norm. Wind a few turns and divide the output voltage by the number of turns and you have the volts/turn. I found that 1 turn would give about 1 volt after rectification and filtering. For 100V out you will need approximately 100 turns, just to give you an idea of what to expect. I made a MOT psu a few months ago, check it out. The voltage drops alot under load, due to the crappy wire I used. (notice that it's not one piece?) Use magnet wire, I think 20-22 AWG would give you the needed amount of turns.
Registered Member #697
Joined: Thu May 10 2007, 12:28PM
Location: Australia
Posts: 22
Thanks for the suggestions. I have experiemented today with a 16v low amp power supply and those extra 4 volts made a noticable difference so I can only image what 24+ would be like. I purchased a larger inductor and some magnet wire for it however I haven't had the time to wind it. (Distracted by a green laser pointer which arrived today).
Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
You are not the first to discover the main limitation of the Marzzilli driver: The rather exotic requirement for a power supply to run it off. Just who needs 30V these days? There are a few options though. You can series two ATX PSU if you first lift the ground connection of one of the PSUs. Usually the output is grounded directly to the case at the screws that hold the PCB in place, cut the tracks and you are ready to go. Another option is to identlfy the voltage feedback path in the PSU and mess with the voltage divider to trick the PSU into providing a greater output voltage. This can work very well, but can also cause a lot of problems if you don't know what you are doing. The best option probably is to hit ebay for cheap 12V transformers with two separate secondaries, they can be put in series and even voltage doubled, and usually take abuse gracefully compared to regulated PSUs.
Both supplies allow some minor adjustment of output voltage. I just received the 36V supply and haven't tried it out yet, but the 48V supply really works well with my ZVS flyback driver. Actually, a little too well. Most flybacks tend to fry pretty quickly. I'm hoping the 36V supply will be a little gentler.
Rick
EDIT -> Crap, I just noticed you live in Australia. Both companies above are in the US. It looks like BG Micro will ship internationally (with some restrictions). So will MPJA, but they require a USD $100 minimum order. Both supplies are pretty light so if you do decide to order, you're mostly just faced with shipping time. If you're in a hurry, modding a couple computer supplies may be the way to go.
Registered Member #63
Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425
Live in Australia? Drop in to Jaycar Electronics and buy one of their 300W toroidal transformers. You can get them with 24V+24V, 40V+40V, etc, secondaries. Parallel them for double current; series them for double 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.