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 #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
OK, one maybe stupid question, can it be a nonpolar electrolytic? I intend to use 4,7uF on instead of stacking a bunch of big 'normal' caps (DRSSTC) They don't seem to have some special disadvantage, except maybe little more internal resistance. I think inductance in nonpolar could be even smaller because cap is physically smaller...?
Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
I have seen lots of people using back-to-back polar electrolytics and I have done so myself with good success. Just remember to put a small plastic cap in parallel to cater for transients.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
MAYBE
Depends what frequency you're operating at NP Al electrolytics are self-resonant in the TC frequency range (from memory) Cheap MKT capacitors work fine below 1 MHz.
Registered Member #58
Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317
I am not sure if its true but I have heard you want a Blocking Cap that is 6 times the sum of your Gate Capacitances. I don't actually use this though, I just use a .1uF (104 Value) Ceramic Cap and it seems to work fine.
Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
You just want it to be big compared to the gate capacitance, because they form a voltage divider, and you want as little as possible of you voltage to be wasted across the blocking cap. I am kind of suspicious about the electrolytics having less inductance, because most of the electrolytics I have taken apart had the connections in the center of the roll and on the outside of the roll, whereas plastic caps are usually wound with "extended foil", so the current does not go round in loops. Maybe some pulse grade electrolytics are done in the same way, though.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Yep, you may be right in the end.
So here are the results, everything is ran as in reality, real GDT, 2x 22nF loads, 3,9 ohm gate resistors (maybe too big), frequency 100kHz (I have a new secondary)
Transistent times for both caps are similar excluding few volts in the end for electrolytic, probably because of ESR. Normal cap shows some more square tip but it's not much better.
Another strange thing I noticed now is the random apperance and dissaperance of the final cycle, makes waveform shaky (scope trigger)
I also saw this on Scopeboy's DRSSTC and I wonder if this is normal, it seems to be a result of interrupter bistable's delay circuit?..
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.
GDT DC blocking cap
