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 #16903
Joined: Thu May 09 2013, 08:00PM
Location: Sumter, SC
Posts: 23
Hello I am building a solid state musical tesla coil and me and my dad were talking about it and I told him I Would need a ~10 amp 120 volt variac to test and isolate the tesla coil from the mains but the only problem is that they cost in the range of $100 so he says that I could use a potentiometer or rheostat to do the same thing. but a since they work on resistance I would need a 1200 watt rheostat which I don't they even make unless it's custom because on digikey the highest is 811 watt.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
No, you would not want to do this. The potentiometer / rheostat would act like a linear regulator and would be highly inefficient, and depending on resistance, may limit the output current of what you would need. Just purchase the variac. I can also guarantee it will be much cheaper than buying a 1200 Watt rheostat from digikey.
You can get a very inexpensive variac on EBAY for less than $50. There are tons on there.
Here is on example I would look at. This is only a 2A one, but look for a similar model rated for 10A.
Registered Member #16903
Joined: Thu May 09 2013, 08:00PM
Location: Sumter, SC
Posts: 23
EasternVoltageResearch wrote ...
No, you would not want to do this. The potentiometer / rheostat would act like a linear regulator and would be highly inefficient, and depending on resistance, may limit the output current of what you would need. Just purchase the variac. I can also guarantee it will be much cheaper than buying a 1200 Watt rheostat from digikey.
You can get a very inexpensive variac on EBAY for less than $50. There are tons on there.
Here is on example I would look at. This is only a 2A one, but look for a similar model rated for 10A.
Thanks alot I told my dad the same exact thing but he doesn't want to believe me
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
Lets say you want only 50% voltage to the load and your rheostat can support that. Then you will have 1200Watts being delivered to the load (assuming that the power number is constant) and 1200Watts being dissipated in the rheostat.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
Most things that blow up usually do it . when power is applied . when the enable/run/go signal is activated . when you think you can get just a bit more ... :( . randomly after running for a while not much can be done about the third or fourth but a mains rated filament bulb in series with the mains can reduce or even prevent serious damage/explosions etc. Once you have the system running then the lamp will be the same as a resistor and full power will not be possible.. but potential costly/embarassing failures will be minimised, once you are confident then the lamp can be removed and full mains applied. Ultimate = variac with lamps and a big red STOP button.
P.S. some circuits work perfectly well when mains is 'switched on' at normal supply voltage, but can fail disastrously at certain (random) voltages.
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.
rheostat or potienometer as a variable voltage input for sstc?
