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 #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
I'm working on the construction of a 50 kvdc floating full-wave (4X) multiplier.
In anticipated use, either the positive or negative output may be grounded, or possibly neither (i.e., it may be used in series with another dc source).
As a matter of safety and practical usefulness, I want to build into it something that would indicate the output voltage, even very roughly.
I was originally planning on building into it a 100 uA meter (in series with a 1 Gohm bleeder resistor network), but I can't seem to find any relatively small-sized panel meters.
Does anyone know if any kind of "miniature" panel meters are available anywhere or does anyone have any other ideas how to do this?
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Some cassette tape decks had miniature meters, they had a needle with a 90 degree bend in it, and were viewed 'end on'. They were approx. 20mm x 8mm, or there abouts. they were used for recording levels, etc. I 'think' they may have been used on Phillips units from the early to mid seventies, but I can't be certain.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
A very simple device is a pith ball electrometer. Simply two balls 1/4 inch suspended between two silk threads. Just having one small globe of styrofoam on a string between the terminals may work. Do you think when the terminals are hot there will be a slight pull on the string?
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
jpsmith123 wrote ...
Hmmm that's more than I thought. Are you sure about that Antonio? If that's true I have to scrap the design.
I was looking at the following chart which made me think it'd be ok.
Antonio wrote ...
55 kV will spark between two 2 cm spheres at more than 10 cm of distance.
This table looks too optimistic. I am using an exact calculation of the electric field between two spheres. The results say that in two balls with 2 cm of diameter separated by 10 cm the maximum surface electric field for +/- 25 kV at the spheres is 27.6 kV/cm. With 54.3 kV between the spheres the field reaches 30 kV/cm, that is the breakdown field for normal air. There are other effects to consider, probably, but this looks reasonable, considering that if the spheres are far apart the maximum voltage is 60 kV, with the maximum surface field reaching 30 kV/cm in all the surface of the spheres.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
I think your calculations are correct as far as they go, but AFAIK, having corona at the electrodes doesn't necessarily imply a breakdown across the whole path between them...I think that's where we have to consult empirical data.
But you've made me wish I did it differently however. I wish I could find some cheap, corona-free connectors rated for 50 kv somewhere.
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.
What's the best way to measure a floating (differential) HV output?
