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 #1565
Joined: Wed Jun 25 2008, 09:08PM
Location: Norway
Posts: 159
Actually.. the parts you need for flyback operation is already in the monitor.
There is the HOT-transistor, the base-drive transformer for it, does capacitors, they are even assembled on the board, as far as you can use that. The tricky part may be to remove the need for the yoke, given you use the board as-is.
Registered Member #3859
Joined: Sun May 01 2011, 03:47PM
Location:
Posts: 179
Erlend^SE wrote ...
Actually.. the parts you need for flyback operation is already in the monitor.
There is the HOT-transistor, the base-drive transformer for it, does capacitors, they are even assembled on the board, as far as you can use that. The tricky part may be to remove the need for the yoke, given you use the board as-is.
I thought of this. Not sure what the yoke is but there is a high voltage, powerful transistor that drives the flyback. Not sure what voltage it uses but it would make perfect sense to just use existing components and circuitry. I was planning on using a flyback transformer that is very old to make sure there is no rectifier diode built into the output.
CRT tvs mostly come from the era of current-controlled semiconductors vs voltage-controlled MOSFETs. I like to work with voltage-controlled semiconductors since it is so easy to design circuits with them where something is either on or off.
Registered Member #3859
Joined: Sun May 01 2011, 03:47PM
Location:
Posts: 179
Antonio wrote ...
You disconnected the mosfets by adding capacitors in series with them and disabled the feedback through the diodes...
I see what you are talking about.
So if I leave the feedback through diodes, but disconnect the shifting voltage (or the voltage used to help open gates through resistive voltage dividers) would it work off 170VDC?
The goal is to have less than 20 volts at gates and not to loose too much power in voltage dividers.
Would it be wiser to use capacitive voltage dividers? Would it be possible to replace R3 and R4 with a capacitive voltage divider?
Did anybody successfully run this circuit with voltages above 40 volts?
Is it possible to disconnect this branch with r3 and r4 and still open gates? I cannot model this circuit in dynamic.
Registered Member #3859
Joined: Sun May 01 2011, 03:47PM
Location:
Posts: 179
Would any of the two circuits make sense? Do I need to have 50X50 windings on my primary to reduce the current? Do I need 470 ohm resistors still?
I can use 24 volts if the maximum gate voltage of my mosfets is greater than 24 volts. Am I correct? I want to use mains voltage, but to have the right to control the current by screwing in the light bulb of an appropriate wattage in to the supply circuit.
Why are you trying to use a Royer oscillator when you could much more easily use a standard half bridge to drive the flyback transformer at whatever input voltage you like. A standard SSTC style driver and half bridge inverter circuit being fed by a variable frequency oscillator will let you adjust output power by moving closer to or away from the resonance point of the flyback, giving you precise control of the output without needing a variac.
It could be as simple as a 555 feeding a UCC37321/UCC37322 pair into a GDT, which drives a half bridge of FDL100N50F MOSFETs. You'd be good up to ~480V DC Bus and capable of switching more amps than your wall can deliver provided you cool the fets well.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Sigurthr wrote ...
Why are you trying to use a Royer oscillator when you could much more easily use a standard half bridge to drive the flyback transformer at whatever input voltage you like. A standard SSTC style driver and half bridge inverter circuit being fed by a variable frequency oscillator will let you adjust output power by moving closer to or away from the resonance point of the flyback, giving you precise control of the output without needing a variac.
It could be as simple as a 555 feeding a UCC37321/UCC37322 pair into a GDT, which drives a half bridge of FDL100N50F MOSFETs. You'd be good up to ~480V DC Bus and capable of switching more amps than your wall can deliver provided you cool the fets well.
Sigurthr is right, there is no reason to try and brute force a Royer oscillator to do things it can not handle with the kind of switches available, the self oscillating nature of this circuit works fine within some limited boundaries and outside of them it burns or needs auxiliary circuits where it gets even more complex than just building a half bridge driver with something like the TL494 IC.
I made a TL494 driver that easily kills the flybacks from over voltage before the bridge explodes:
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.
Another Flyback Driver circuit... Why use 24 volt power supply? I want to use 169.70 VDC
