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 #142
Joined: Sat Feb 11 2006, 01:19PM
Location:
Posts: 102
What about that circuit do you understand, and what do you not understand? Where did you find it? Did it occur to you that you might want to provide some context? Are you looking for a deeper understanding of the way a half-bridge driver works?
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Those aren't snubber capacitors, they're just the usual RF bypass caps. Notice they're not actually connected across the MOSFETs, just across the DC bus.
He could have left them out and returned the work circuit straight to the negative terminal of the DC bus cap, but maybe he wanted isolation for safety.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
C4, C5 in parallel is 2 ufd. C9 is in series. The work coil is in series with 0.67 ufd effectively. If C10 resonates the work coil, then the load (heat) divided by the voltage across the coil would be the amps that are limited by the reactance of 0.67 ufd. Of course Gnd and + are assumed to be a constant voltage source with zero impedance,but it probably isnt, so messing with the magic that makes the thing work could be interesting.
Reduce the 0.67ufd and the thing would produce less heat.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Steve McConner wrote ...
Those aren't snubber capacitors, they're just the usual RF bypass caps. Notice they're not actually connected across the MOSFETs, just across the DC bus.
He could have left them out and returned the work circuit straight to the negative terminal of the DC bus cap, but maybe he wanted isolation for safety.
And now it gets interesting...
This is exactly what I would have thought. Instead of the potential on the transformer being Vc and Vc/2, it is now Vc and 0. However, it does not work. If I take the lead going to the capacitor divider between C4 and C5 and connect it to ground, I don't get a clean square wave and the current just shoots up as I increase the supply voltage. I don't understand why the divider is necessary.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
" If I take the lead going to the capacitor divider between C4 and C5 "
What do you think these capacitors divide? they are connected across a DC source blocked by 2500 ufd.
Once the coil current passes through a capacitor, it become 'alternating current', whatever waveform, sine, square or something between, its still AC. and C4, C5, and C9 ( 0.67ufd) are part of tuned circuit with L1.
Change that value of capacitance--it changes the tuning. By grounding the low end of the tank 0.67 was changed to 1ufd,
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Maybe as Radiotech says, the capacitors are small enough that they provide enough reactance to mess with the tuning. You might need to retune the frequency if you remove them, or make C9 smaller to compensate.
Or maybe your C9 is shorted, so when you remove them there's no DC blocking any more.
Also, if C4/C5 are mounted near to the MOSFETs they are helping to clean up the DC bus. So even if you don't return the work circuit to the centre tap of them, maybe you shouldn't remove them altogether.
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.
inverter snubber capacitors
