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 #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Im definitely going to etch a new board, based on the UC28023D2 single switch CCM ic, which has a 0 to 90% duty cycle capability, and ill use a current transformer for cycle by cycle current limiting.
i may try primary side regulation, but thats experimental, ive never done this kind of regulation before.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
Why would you need to? The concept is clear from the schematics, the first is pure PWM ... the second is PWM with current limiting. Neither has voltage feedback though, so only the snubber design is useful to you.
Don't see why you would use a current transformer BTW. What is wrong with shunts under the MOSFET like this circuit?
PS. AFAICS this regenerative snubber is going to be ringy as hell, is going to make primary side feedback more difficult ...
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Pinky's Brain wrote ...
Why would you need to? The concept is clear from the schematics, the first is pure PWM ... the second is PWM with current limiting. Neither has voltage feedback though, so only the snubber design is useful to you.
Don't see why you would use a current transformer BTW. What is wrong with shunts under the MOSFET like this circuit?
Im reading up on snubbers right now, from the TI/Unitrode PDF's. His is hard to figure out...
the problem with shunts is that they generate heat, i blew some of my 0.5 ohm ones out pretty easilly. id rather use a current transformer for that reason alone... also i need one for a 50 amp circuit i have coming up, so might as well learn now anyway.
EDIT: im thinking of using the 170 VDC from rectified mains for the primary and single switch to the flyback,i think pins 10 and 11 will be my new primary.
Im trying to develop a whole new series of power supplies that dont need any iron core line transformers, my radio shack ones are too expensive, weak, and they're heavy...
i may be able to just use rectified mains for the UC3526AN, the FAN4800IN, and the UC28023/and 5, and the UC3844N. still looking at the examples in the datasheets though.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
It's a picture of a metal shunt for current sensing, it's basically nichrome resistance wire on steroids. Just search for shunt on digikey and look at the results in resistors and specialist resistors.
AFAICS the snubber transfers the energy from the primary leakage induction to the snubber capacitor when the MOSFET turns off (it doesn't keep ringing of course, I was wrong about that). When the MOSFET turns on the capacitor starts a partial oscillation with the inductor, initially the voltage at the right side of the capacitor will be negative, when it rings up with the inductor they can dump energy in the main power supply smoothing capacitor (ie. regeneration).
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.
HV Flyback Bench Top Power Supply for Lab.
