Hi DF96
B(AC) = [ U(AC) x 10^8 ] / [ sqr (2) * (Pi) * S * f ]
If U(AC) is fixed, I would say it is the other way around.
I hope it's a typo.
Best regards
Johann
Can you explain better, I think slowly and still do not understand.
With math, please, we are talking about physics, not philosophy.
In post # 36 I took the trouble to do all the calculations, and I'm just a TV repairman, I can not expect less from you, having a Ph.D. degree.
If you're right I will apologize, as appropriate between gentlemen.
Best regards
Johann
Maxwells original equations are well beyond forum chit-chat I suggest. Specific design equations, eg. for transformer winding design, are meant to be assessed in that context (eg. a winding of turns on a core with a voltage applied to the winding and all flux passing through the entire winding).
Heater current/voltage impact has been a problem since the dawn of valves. They've been writing technical papers on the topic for more than 80 years.
http://dalmura.com.au/projects/OPERATION OF THE HEATERS.pdf
There is a plethora of reviewed technical articles on heater related topics - even down to the field 3d orientation and magnitude resulting from twisted cables of various configurations (ie. if you want minimal induction to another wire then don't cross at a simple right angle - get that protractor out ;-).
Ciao, Tim
Heater current/voltage impact has been a problem since the dawn of valves. They've been writing technical papers on the topic for more than 80 years.
http://dalmura.com.au/projects/OPERATION OF THE HEATERS.pdf
There is a plethora of reviewed technical articles on heater related topics - even down to the field 3d orientation and magnitude resulting from twisted cables of various configurations (ie. if you want minimal induction to another wire then don't cross at a simple right angle - get that protractor out ;-).
Ciao, Tim
Sa can we conclude that static electricity (huge voltage, no current flowing) produce a huge magnetic field?
No! It is very simple:
MAGNETIC fields are proportional to CURRENT.
ELECTRIC (aka. electrostatic) fields are proportional to VOLTAGE.
An ELECTROMAGNETIC field is the combination of the two.
curl B = mu_0 J (current) + mu_0 eps_0 dE/dt (time differential of electric field)
See Wikipedia.
As I said, the magnetic field has two 'sources': current and rate of change of voltage with time. I say 'sources' rather than sources because Maxwell's equations do not specify causality but merely equate things.
Similarly, the electric field has two 'sources': charge and rate of change of magnetic field. The big difference is that for the magnetic field both are curling sources, but for the electric field the charge 'source' is diverging. If you don't know vector calculus this might not mean much.
Why are we discussing elementary EM theory, available widely on the web and in many textbooks at all levels of understanding?
See Wikipedia.
As I said, the magnetic field has two 'sources': current and rate of change of voltage with time. I say 'sources' rather than sources because Maxwell's equations do not specify causality but merely equate things.
Similarly, the electric field has two 'sources': charge and rate of change of magnetic field. The big difference is that for the magnetic field both are curling sources, but for the electric field the charge 'source' is diverging. If you don't know vector calculus this might not mean much.
Why are we discussing elementary EM theory, available widely on the web and in many textbooks at all levels of understanding?
Sa can we conclude that static electricity (huge voltage, no current flowing) produce a huge magnetic field?
LOL!
Yes the penetrating insight here has been enormous.
Taking the Electromagnetic Field in hand,
We can see by using the Quantum Tunneling Model here:
that we get a Spin-field around each Electron-+Ion pair as follows:
This results in the following Energy Exchange Evolution:
Looking at the alignment of the metal-crystal domains, we see:
Complimentary Attraction of Ionized particles to the Cathode Surface gives:
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A quick calculation shows:
And so we can expect:
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You do not know even write correctly Maxwell's equations.LOL
Where did you study physics?
That's not what I asked, the equation you mention is one of Maxwell's equations, but badly written, the magnetic field is H, not B, and the electric field is D, not E, J is current density, not current.
If the medium is not "homogeneous and isotropic", you can not treat epsilon and mu as in high school.
If by "time differential" you mean "time derivative" is also incorrect, because that is a partial time derivative.
See Eq (4) in the attachment, there is well written.
Oh! BTW, mind you, just in case that curl ( ) = [nabla operator] x ( )
div ( ) = [nabla operator] . ( )
Change in system of units is irrelevant.
I think you must use another more serious reference than Wikipedia.
I can understand that you confuse E and D, B and H, is quite common, even in textbooks, but I can not believe that you confuse derivative with differential.
Where did you study mathematics? or is the language barrier?
Again WRONG, see te attachment, Eq(4), what you call current, is the current density J, and what you call rate of change of voltage with time, is the displacement current: partial time derivative of D.
Voltage, not rate of change of voltage with time, is implicit in Eq(3), as I showed in Eq(7)...Eq(20)
You're right, the calculations made by my granny, I am just a TV repairman.
Good idea, you could really use one of them.
As I said, we are talking about physics, not philosophy, and you have not made any calculation to show me what I asked, that ironically is the same as you "corrected me".
I remind you that the language of physics is mathematics, leave the blah, blah, blah, for another forum.
I expected a proper response, yours is pathetic, you can not even explain what you "corrected me", not even know Maxwell's equations, you disappoint me.
I think that you bought your Ph.D.
Best regards
Johann
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Sa can we conclude that static electricity (huge voltage, no current flowing) produce a huge magnetic field?
Not really, if you take the trouble to look Maxwell's equations, Eq(1)...Eq(4)
In the case of static charges the only equation that is still remain useful is Eq(1)
But you already have seen in high school.
Best regards
Johann
Hi DF96
You really are amazing.
Since my first post in November 2010, systematically you persecute me, criticize me for no reason, you ashamed me every time you can.
And now you're the victim?
I remember one of my dogs, is a PITA, almost like you, but I can not punish him, places a face of "I was not".
Better not keep on going, lest we be friends someday.
Best regards
Johann
Please keep the discussion to technical issues.
I prefer not to even attempt to regurgitate my own distant recollection of 3rd year physics lectures, which is about the level of uni where Maxwells equations were only just starting to become understandable (both from a mathematics, physical and electrical engineering appreciation). I suggest this is the wrong forum to espouse any such topic, and further suggest diverting such effort to the submission of a peer-reviewed journal paper for us all to appreciate in the future.
The OP was floating two poorly detailed views of why two people had moved from using AC to DC heaters. The background or reasoning to those two reactions wasn't clearly described then, and hasn't been advanced much in this thread.
Ciao, Tim
The OP was floating two poorly detailed views of why two people had moved from using AC to DC heaters. The background or reasoning to those two reactions wasn't clearly described then, and hasn't been advanced much in this thread.
Ciao, Tim
Hi Bigun
Nice to see you around here.
Your idea may be an improvement for my suggestion in post # 3 and post # 22, and if the polarity reversal can be done every time you turn on the amplifier, would be almost perfect.
Even for long-term effects, especially with direct heated cathodes.
Best regards
Johann
I am struggling to appreciate how the act of reversing the polarity of a DC heater supply at infrequent intervals, such as when an amp is turned on or off, could provide some form of benefit. And vice versa, I'm also struggling to appreciate how a DC heater supply could degrade a valve or amps performance over time.
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