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 #14432
Joined: Sat Apr 20 2013, 01:18PM
Location:
Posts: 18
Hi, first of all, I am really sorry if I posted in the non suitable part of forum, I searched and couldnt know where to post this question that has been eating my mind for some time.
I know air core transformers like a Tesla Coil have a resonance frequency where the amplitude will be greatest in the secondary i.e. the secondary voltage output is greatest when primary is tuned or oscillating to the resonant frequency of the secondary.
Lets say we have an air core secondary that resonates at 1mhz (just as an example). Now I really wonder what would happen if you drive that air core transformer with for example with a different frequency than 1mhz?, maybe like feeding the primary with very low frequencies 1khz or 50khz instead or like higher freuencies like 50mhz?(just an exaggerated example to show my point)
What Would happen to the amplitude and FREQUNCY output of the air core secondary ?or what would the frequency of the secondary be ? would the secondary still oscillate at 1mhz at very low amplitude regardless wether the primary driving frequency is as low as 1khz or much higher than 1ghz? or would the secondary also oscillate close to these different frequencies ?
Thanks for your time reading my question. Best Regards
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Think of the coil assembly as a filter. If the input waveforms are sinusoidal, the output frequency must be equal to the input frequency. The series resonance tells us at which frequency the output voltage will be the greatest with input voltage kept constant. Driving the coil at low frequencies will result in large current draw due to the low primary inductance, possibly excessive heating in the primary coil and very low output voltage from the secondary coil. With driving frequencies higher than the series resonant frequency, you get additional voltage peaks at the harmonics of the fundamental resonant frequency.
Registered Member #14432
Joined: Sat Apr 20 2013, 01:18PM
Location:
Posts: 18
Thank you Dr dark current. Let me see if I get this part correct, so the frequency of the secondary will indeed be the same one as the one in the primary if it is sinus. I understood already that the voltage is greatest(i.e. most efficient operation) happens when in resonance , but I thought the frequency of the secondary was also always the same but I am obviously wrong. This brings me to some related matter: Music by Frequency modulation in SSTCs. I asked everyone who owned these sstcs and they said that: "as the prim freq changes, the sec. freq. DOES NOT change at all but it is the amplitude i.e. the sec. voltage that goes up and down ? I am confused as this sound a little contradicting to what you said? My guess is that it depends on how far away the "drive frequency" is from the sec. resonant freq? , maybe??
Registered Member #4104
Joined: Fri Sept 23 2011, 06:54PM
Location: Uk .
Posts: 122
With FM modulation in a SSTC , you are pulling the drive frequency away from the resonant frequency of the secondary buy a small amount at the frequency of the audio , This cause variation in the secondary output arc , thus audio is produced by the arc
Registered Member #14432
Joined: Sat Apr 20 2013, 01:18PM
Location:
Posts: 18
TwirlyWhirly555 wrote ...
With FM modulation in a SSTC , you are pulling the drive frequency away from the resonant frequency of the secondary buy a small amount at the frequency of the audio , This cause variation in the secondary output arc , thus audio is produced by the arc
That's how I thought it worked with the FM SSTC
Yes exactly, but I wonder what exactly this variation is? according to what I was told by musical FM sstc builders (someone showed me an oscilloscope screen too, ha?)is that the amplitude of the secondary i.e. the voltage varies only , while secondary. frequency does not change at all . Here I got the answer that the secondary frequency does change accordingly? I was always not sure. Thanx for your input.
as the prim freq changes, the sec. freq. DOES NOT change at all but it is the amplitude i.e. the sec. voltage that goes up and down ? I am confused as this sound a little contradicting to what you said? My guess is that it depends on how far away the "drive frequency" is from the sec. resonant freq? , maybe??
A frequency modulated sine wave does not have a single frequency. The same is true for an amplitude modulated one. It is a mixture of different frequencies. You get e.g. an amplitude modulated sine by adding two (not modulated) sines of slightly different frequencies. Each fo these sines goes to the secondary unaltered in frequency. What changes, are the relative amplitudes and phases. A frequency near the secondary res f will come out relatively stronger than one further away. These changes in amplitudes and phases add up to the effect you observe, e.g. an amplitude modulated sine wave for a frequency modulated input.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
leviterande wrote ...
Yes exactly, but I wonder what exactly this variation is? according to what I was told by musical FM sstc builders (someone showed me an oscilloscope screen too, ha?)is that the amplitude of the secondary i.e. the voltage varies only , while secondary. frequency does not change at all . Here I got the answer that the secondary frequency does change accordingly? I was always not sure. Thanx for your input.
I think it's something like this:
The sound varies at up to/less than 20kHz, but the secondary frequency is much higher. The amplitude of the secondary varies with the frequency of the sound, but the frequency of the secondary oscillates at a much higher frequency than the sound, It's a bit similar to radio, where the carrier wave is a much higher frequency, but the amplitude varies according to the frequency of the 'super-imposed' sound.
Registered Member #14432
Joined: Sat Apr 20 2013, 01:18PM
Location:
Posts: 18
Ash Small wrote ...
leviterande wrote ...
Yes exactly, but I wonder what exactly this variation is? according to what I was told by musical FM sstc builders (someone showed me an oscilloscope screen too, ha?)is that the amplitude of the secondary i.e. the voltage varies only , while secondary. frequency does not change at all . Here I got the answer that the secondary frequency does change accordingly? I was always not sure. Thanx for your input.
I think it's something like this:
The sound varies at up to/less than 20kHz, but the secondary frequency is much higher. The amplitude of the secondary varies with the frequency of the sound, but the frequency of the secondary oscillates at a much higher frequency than the sound, It's a bit similar to radio, where the carrier wave is a much higher frequency, but the amplitude varies according to the frequency of the 'super-imposed' sound.
I believe you perhaps misunderstood me, yes I know the general operation of a carrier wave and. I wondered if it is only the "amplitude" that changes in the secondary in an FM SSTC singer, that is what I believed indeed, that it is the "amplitude alone" changes in the secondary but if you look at Dr darks post, he means(I believe as I read it ) that the secondary frequency should follow the primary frequency! " the output frequency must be equal to the input frequency"! I am confused as there seems to be some contradictions ?
Uspring Your answer seems to be the most correct one?, I am still trying to decode it though ;)
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Well, I can see that by varying the primary frequency, you 'could' obtain a similar effect, but I don't understand how such 'frequency modulation' can be implemented, if that's the correct term to use.
I wondered if it is only the "amplitude" that changes in the secondary in an FM SSTC singer, that is what I believed indeed, that it is the "amplitude alone" changes in the secondary but if you look at Dr darks post, he means(I believe as I read it ) that the secondary frequency should follow the primary frequency! " the output frequency must be equal to the input frequency"!
Strictly speaking it does not make much sense to talk about _the_ frequency of a frequency or amplitude modulated sine wave. Consider e.g. an amplitude modulated sine wave:
sin(w*t) * sin(wm*t), i.e. a frequency w modulated with a modulation frequency wm.
This can be rewritten as
0.5*cos( (w-wm)*t ) - 0.5*cos( (w+wm)*t )
So actually the amplitude modulated sine is a sum of 2 sines of different frequencies. There is no single frequency you can assign to this sum. For an FM modulated sine, the situation is similar. On the secondary side there will appear a mixture of the same frequencies, as Dr. DC said. Due to resonance effects, their relative amplitudes and phases change but it will still be a mixture of frequencies.
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.
A question about air core transformers!?
