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 #3429
Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288
I discovered something rather amazing that I wanted to share with my high voltage friends. After building my flyback driver I started to experiment with plasma speaker designs. I tried the traditional spark gap (long, thin arc) which worked fairly well, but I wanted to try some unconventional designs to see if I can get better (louder) audio output. In my research, I found some very old papers that describe a plasma speaker made from a quartz tube with a metal central electrode, which is surounded by a grounded metal housing. The h.v. power supply was amplitude modulated at audio frequencies, and the quartz tube was mechanically fitted to an exponential horn which amplifed the sound. Well, I got the idea of using a 100 Watt halogen lamp as the speaker transducer, and it works! (see photos below). I tried applying 120V to the lamp in order to see if that made any difference, but it did not, so I run it without heating the tungsten filament.
With the halogen lamp mounted in its holder, the reflector actually strengthens and directs the sound just like a regular speaker! It's actually fairly loud and sounds pretty good, although there is some noticable distortion when playing music. When playing only voice, the sound is loud and clear, and it rivals any regular paper cone speaker of small size! The only negative issue with this design is the production of ozone, and there's a LOT of it! After running this "speaker" in my shop (about the size of a 2-car garage) for about 15 minutes, the odor of ozone was overwhelming, and I had to open up the doors and windows to air it out!
I noticed that I got best sounds when the frequency and modulator DC voltage were adjusted just right. Too much or too little voltage, or if the right frequency wasn't set, then the audio quality and/or amplitude were very much degraded.
Registered Member #3429
Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288
Patrick wrote ...
Are the two loose metal tubes always at the same potential due to that wire bridge?
Yes. I would have used one long tube, but the lamp has a little evacuation stub that protrudes out the center of the glass envelope, and therefore I was not able to use one long metal tube. The glass stub is in the rear, and so it does not show in the photos.
I probably should explain about the TIP41C transistor that's just hanging on some wires in the picture. Originally, the DC regulator was just a NPN power transistor, and I fed the modulation into its base with an audio transformer. But I needed to turn the volume on my radio way up, to the point of distortion, in order to get good volume output from the plasma speaker. So, I added the TIP41C transistor in a darlington configuration which gives the modulator circuit much more gain. I plan to mount it on the circuit board so that it looks more professional instead of like a newbie hobby project!
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.
Halogen lamp plasma speaker!
