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 #621
Joined: Sun Apr 01 2007, 12:37AM
Location:
Posts: 119
Hi all, 2 questions I was thinking of are -
1. Can you parallel 2 diodes (for example in a rectifying circuit) to double the current handling capability? (assuming that they are identical model and manufacturer, rating, etc.)
2. Can you series diodes to increase voltage capability? (assuming the same...identical ratings, etc.)
Registered Member #540
Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969
You can series them to increase your PIV rating but you might want ~50% head room to be safe because of imperfections they will see slightly different voltages. For paralleling them it would just be best to get a higher current diode because of imperfections the diodes will pass different currents so one might pass all (or most of) the current while the other won't.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
With two IDENTICAL diodes putting them in series will double the voltage rating to allow for slight differences in leakage current and (in ac circuits) capacitance in real diodes some de-rating is common. For dc circuits you can pretty much simply add the voltage ratings. (this is due to rapid increase in leakage current as the rated voltage is approached - avalanche breakdown - don't worry about that for now)
When two ALMOST identical diodes are used in parallel how well they share the current depends on the actual current!
At low currents real diodes behave quite like 'ideal' diodes look here
so when one diode is a little hotter than the other it will have a lower voltage and draw more current and get hotter until one diode carries most of the current. Here I'm talking about voltage up to 0.6V and current up to 1mA for a typical diode.
However, at higher currents when we refer to diodes as rectifiers the series resistance of the diodes becomes more important this is not part of the 'ideal' diode model it's due to the resistance of the silicon and bonding - not the 'ideal' junction. So at high currents two similar diodes WILL share the current pretty equally. In this case the rectifier will have more than 1V across it and an amp or more through it.
Registered Member #621
Joined: Sun Apr 01 2007, 12:37AM
Location:
Posts: 119
Hey guys thanks for the quick replies, I forgot to mention, see I bought four 10kV @1 Amp diodes to rectify my 4kV RMS @ 90mA source.
See I bought these for making a Full Wave Bridge rectifier, so now I have 4 of them. But with my new Full Wave Voltage Doubler design, I only need 2 of them. They are pretty beefy, they look like a black Now and Later candy bar with screw terminals on each end. So I am not sure if I should just use 2 and keep 2 as spares, or series or parallel them to make use of all 4 now.
Registered Member #540
Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969
You may want to put under oil then for better cooling because it's running pretty close to the rated max current draw. I think mineral oil would be fine (no vegetable or cooking oil) (correct me if I'm wrong about the mineral oil).
EDIT: Oops sorrry about that. sometimes I think that 100mA is 1A but I have to remeber that it's 1000mA that is 1A
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.
2 Diode Questions
sorrry about that. sometimes I think that 100mA is 1A but I have to remeber that it's 1000mA that is 1A
