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 #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
This is what I've used before I found a real (RCA) surplus one in a store.
The best thing is to get a cheap DIMM and make your tests on a low current source first. Once you see what you're going to need, then you'll feel more comfortable. I would really pay attention to design. Commercial ones have a small "strike ring" in the handle & it can be an important consideration.
Some issues: if you can find quality HV resistors (high wattage ceramic) that can really help - spend your money there as most other items can be designed effectively at home.....Make the thing a bit longer than commercial ones; it's a margin of safety in unique circumstances. And remember that most things that you'll make won't take the place of a professionally manufactured one. So use caution, even if everything seems like it performs well. A cheap tester is a must. Don't run (even a good design) on your $400 Fluke.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
a 100 kv cap can be made by 2 ball bearings, under oil, canola or whatever, i use 0.5" diameter balls 1 inch apart under oil. which gives 0.7pF @150,000 volts HF, squarewave. but i use an oscope, so as not to be misconstrued as if i were a communist coward. i do not use a DMM as waveform can be as important as wave amplitude. i will post pics after i sleep.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
With such a small capacitance you will need quite large resistors for the voltage divider to keep RC times high enough for low rep rates (and a high input impedance amplifier of course, say a TL081).
Could you make a plate capacitor out of foil-paper-plastic-paper-foil in oil and then pulled vacuum for a day? (The paper wicks, so the air should be pulled out.) Maybe fold the edges of the foil and put some extra layers of paper around the rims?
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Pinky's Brain wrote ...
With such a small capacitance you will need quite large resistors for the voltage divider to keep RC times high enough for low rep rates (and a high input impedance amplifier of course, say a TL081).
Could you make a plate capacitor out of foil-paper-plastic-paper-foil in oil and then pulled vacuum for a day? (The paper wicks, so the air should be pulled out.) Maybe fold the edges of the foil and put some extra layers of paper around the rims?
My vacuum pump [refrigerator compressor] burned itself up. Great suggestion though. I'll try it when i find another junker fridge. Those pumps can pull quite a strong vacuum.
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.
measuring high voltage.
