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 #3637
Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068
Looking at this it seems to be a BJT based royer; I was curious if this design still has the problems of a MOSFET based one, and if it was perhaps possible to add some protection (a la zener diodes or something) to the bases of the transistors. Perhaps some squaring up could also help with heating, and since it's using a feedback winding I wonder if it would still have parasitic oscillation issues.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hi
Read the RogerinOhio's induction heater thread, there has been some discussion there.
The great thing about bipolar transistors is that they can be biased into linear region very easily, using a simple resistor from base to Ucc, while for mosfets it's a pain in the ass, even more so because of NTC of their treshold voltage.
The original mazzili circuit is terribly biased; it latches hard with one switch on, and other off if anything such as excessive ringing disrupts the oscillation. This is what generally blows it up.
You could try the circuit as a flyback driver, with two 2N3055's or something - that would probably be the "right" way to use them for a flyback driver, if there is a right way to use them for anything today!
I suspect you might need to play with the value of pullup resistors, and perhaps add BE protection diodes as well as some resistance in series with feedback winding because of low gain of the transistors.
Note that operating frequency will need to be very low, 10-20kHz. I'm currently researching whether HOT's could be used this way, in order to drive a big induction heater.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Dr. Pork wrote ...
Note that operating frequency will need to be very low, 10-20kHz. I'm currently researching whether HOT's could be used this way, in order to drive a big induction heater.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
Perhaps if you added a resistor, gate to source, the circuit would work. The feedback from the 10T coil is a current flowing in the winding and damping the core, slightly. Bjts are current amps.
Registered Member #3637
Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068
Well, the reasoning behind HOT's is due to the high circulating voltage and current in resonance in a ZVS driver. It's around pi * input voltage, so with 170 vDC in, it would put out arouuund 550 volts. with higher voltages (like 220, or above) the voltage starts to become too much for conventional BJT's or MOSFET's and thus HOT's become a more viable option... Only issue is driving the base!
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
The HOTs for TVs might have an inbuilt diode snubber . The are made for a specific drive pulse width of about 12 uSec. for NTSC sets. As repairmen we checked this carefully when a transistor was changed out, because if it was wrong the new part would blow out in weeks.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
IamSmooth wrote ...
How big are you shooting for?
Hi
I'm attaining some 25A HOT's which I in the end might use several in parallel, or in a current fed H bridge to increase the possible input voltage. For it to be of some use I'd expect power output of some 10kW or so in the end.
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.
Royer Oscillator with BJT's
