No, not my reference source but his. In a discussion about 'electron clouds' in valves he refers me to a poor Wikipedia entry on electron clouds in accelerators. I was merely pointing out that this is irrelevant.
Where did I say that distortion is not related to linearity?
He keeps wanting to reduce space charge, because he seems to think it creates. nonlinearity. I keep pointing out that space charge is a necessary part of normal valve operation. Linearity in normal triode operation is created by the grid and anode having the same 3/2 power law, due to geometry. Getting rid of space charge increases noise (that is how noise diodes work) and damages the cathode: it is known as temperature-limited operation. Is that sound design practice?
Where did I say that distortion is not related to linearity?
He keeps wanting to reduce space charge, because he seems to think it creates. nonlinearity. I keep pointing out that space charge is a necessary part of normal valve operation. Linearity in normal triode operation is created by the grid and anode having the same 3/2 power law, due to geometry. Getting rid of space charge increases noise (that is how noise diodes work) and damages the cathode: it is known as temperature-limited operation. Is that sound design practice?
Hi jmillerdoc
Thank you for coming to my rescue !!!
I agree with you and that was the point all the time: distortion is due to nonlinearity in valves, and yes electron cloud effect in a valve is called space charge, that affects linearity.
I'm sorry if I insist with Planck constant experiment, it was made with a vacuum photodiode and reveals that space charge increase significantly valve nonlinearity, even at Quantum levels. I'm sorry, but the paper file is corrupted and big to upload.
I'm sorry for the Wiki, as I said my reference are Landau-Lifshitz, Cohen and why not Jackson's Classical Electrodynamics, but I haven't a scanner, neither the time.
I'm not an Electronics Engineer, I don't know the right search, BTW for the level of discussion Wiki is enough.
I made a thought experiment with an underrated valve, and the explanation from my little brain was the electron cloud effect.
Best regards
Johann
Thank you for coming to my rescue !!!
I agree with you and that was the point all the time: distortion is due to nonlinearity in valves, and yes electron cloud effect in a valve is called space charge, that affects linearity.
I'm sorry if I insist with Planck constant experiment, it was made with a vacuum photodiode and reveals that space charge increase significantly valve nonlinearity, even at Quantum levels. I'm sorry, but the paper file is corrupted and big to upload.
I'm sorry for the Wiki, as I said my reference are Landau-Lifshitz, Cohen and why not Jackson's Classical Electrodynamics, but I haven't a scanner, neither the time.
I'm not an Electronics Engineer, I don't know the right search, BTW for the level of discussion Wiki is enough.
I made a thought experiment with an underrated valve, and the explanation from my little brain was the electron cloud effect.
Best regards
Johann
12au7 as Mu follewer or srpp
I did extensive tests on using the 12au7, 6bk7, and 6sn7 tube in this mode
I built a tube mike preamp, using two 12au7s as line out trans stage.
Running three triodes on bottom, and one on top gave me the most output at the lowest impedance
Same with other tubes, running two or three triodes in parallel on bottom and one on top gave much more power.
The surprise tube was a 6gu7, a lot more low impedance drive than a 6sn7!
I have to find my notes, then I can publish
So if you use on 12au7 in parallel on bottom, and one triode on top, then you have a third triode for the bottom.
I did extensive tests on using the 12au7, 6bk7, and 6sn7 tube in this mode
I built a tube mike preamp, using two 12au7s as line out trans stage.
Running three triodes on bottom, and one on top gave me the most output at the lowest impedance
Same with other tubes, running two or three triodes in parallel on bottom and one on top gave much more power.
The surprise tube was a 6gu7, a lot more low impedance drive than a 6sn7!
I have to find my notes, then I can publish
So if you use on 12au7 in parallel on bottom, and one triode on top, then you have a third triode for the bottom.
I don't think he means to say literally get rid of the space charge (electron cloud) but to overcome it's adverse effects. It does have adverse effects as well as good effects (clearly without a cloud of electrons created by the thermionic effect there would be no electron tube to speak of) Unfortunately, in triodes at higher frequencies, the capacitance between the anode and grid electrodes can cause positive feedback, regeneration, or oscillation, or other reactances with the circuit. As i rcall, adding various grid in part works by reducing the inter tube capacitances which effect a whole host of things.
All i am saying is with the possiblity of language barriers here internationally we should be careful not to jump to conclusions and try to read between the lines when we can.
As far as linearity it is inferred....
All i am saying is with the possiblity of language barriers here internationally we should be careful not to jump to conclusions and try to read between the lines when we can.
As far as linearity it is inferred....
Hi DF96
Neither Landau, neither Lifshitz, neither Jackson wrote anithing about valves, only basic Physics that lets us understand the Laws of the Universe.
If you wish to read
Electrodinámica Clásica-John David Jackson-Editorial Alhambra-Segunda edición 1980-Capítulo 15-Página 713-Radiación de frenado
15.1. Radiación emitida durante las colisiones
I'm sorry it's in Spanish, but I think the John Wiley & Sons edition can be consistent.
Théorie des Champs-Landau et Lifshitz-Physique Théorique-Tome II-Éditions MIR 1970-Chapitre IX-Page 242-Rayonnement de Freinage
70. Rayonnement lors d'interaction coulombiene
I'm sorry it's in French, but I hope is consistent with your copy.
Lectures are about colitions between charged particles.
Like electrons (good boys) with electrons of the cloud (bad boys)
Any good book about Quantum Mechanics can illustrates Planck constant measure experiment.
But I will tell a simplified story, and I hope you understand my point.
Einstein eq. for photoelectric effect
E = h f
Gives us measure h as the slope of the straight-line E(f), I used a vacuum photodiode, a monochromator as light source, a Voltmeter and a pico-ammeter,
with the pA-meter good I obtained
h = (6.62 +/- 0.07) x 10^-34 J s
When the most sensitive scale of pA-meter was broken (Keithley) I must use a less sensitive scale, with more photons, and
h = (2.55 +/- 0.55) x 10^-34 J s
The reason? more photons => more electrons => more electrons in the cloud=>electrons arived at anode with less energy due to collisions.
Curiously the straight-line became more and more in a curve like a valve curve, (of corurse I used a vacuum photodiode)
The conclusion was the electron cloud afected severely the valve linearity.
Neither Landau, neither Lifshitz, neither Jackson wrote anithing about valves, only basic Physics that lets us understand the Laws of the Universe.
If you wish to read
Electrodinámica Clásica-John David Jackson-Editorial Alhambra-Segunda edición 1980-Capítulo 15-Página 713-Radiación de frenado
15.1. Radiación emitida durante las colisiones
I'm sorry it's in Spanish, but I think the John Wiley & Sons edition can be consistent.
Théorie des Champs-Landau et Lifshitz-Physique Théorique-Tome II-Éditions MIR 1970-Chapitre IX-Page 242-Rayonnement de Freinage
70. Rayonnement lors d'interaction coulombiene
I'm sorry it's in French, but I hope is consistent with your copy.
Lectures are about colitions between charged particles.
Like electrons (good boys) with electrons of the cloud (bad boys)
Any good book about Quantum Mechanics can illustrates Planck constant measure experiment.
But I will tell a simplified story, and I hope you understand my point.
Einstein eq. for photoelectric effect
E = h f
Gives us measure h as the slope of the straight-line E(f), I used a vacuum photodiode, a monochromator as light source, a Voltmeter and a pico-ammeter,
with the pA-meter good I obtained
h = (6.62 +/- 0.07) x 10^-34 J s
When the most sensitive scale of pA-meter was broken (Keithley) I must use a less sensitive scale, with more photons, and
h = (2.55 +/- 0.55) x 10^-34 J s
The reason? more photons => more electrons => more electrons in the cloud=>electrons arived at anode with less energy due to collisions.
Curiously the straight-line became more and more in a curve like a valve curve, (of corurse I used a vacuum photodiode)
The conclusion was the electron cloud afected severely the valve linearity.
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Hi ElectricMan
Please, publish your results
Hi jmillerdoc
Yes, without the electron cloud we haven't a valve anymore, I'm not so fanatic.
Your diagnostics looks good to me, I don't know about the capacitance and feedback part, but I agree with you in almost everything.
There are people who undestand that they want understand.
Believe me, the electron cloud/space charge can be good, but for me was a total PITA.
Day by day broken my mind....until my discovery
Please, publish your results
Hi jmillerdoc
Yes, without the electron cloud we haven't a valve anymore, I'm not so fanatic.
Your diagnostics looks good to me, I don't know about the capacitance and feedback part, but I agree with you in almost everything.
There are people who undestand that they want understand.
Believe me, the electron cloud/space charge can be good, but for me was a total PITA.
Day by day broken my mind....until my discovery
So your personal opinion that space charge reduces valve linearity in a thermionic triode is based on a photoelectric diode experiment to measure Planck's constant? The former is based on voltage change; the latter on light frequency and intensity. Have you ever wondered why the standard valve textbooks never mention this effect you have discovered?
I am aware of the possibility of language problems, which is why I have given popilin the opportunity to explain his ideas so I can see where he gets his strange idea from. I suspect he is confusing emission (whether thermionic or photoelectric) with total current. In the photodiode all the electrons emitted end up at the anode. In a normal triode this is not the case. Far from being a problem, the space charge is a necessity. Not to be reduced, but encouraged.
What has this got to do with linearity at audio frequencies?jmillerdoc said:
I am aware of the possibility of language problems, which is why I have given popilin the opportunity to explain his ideas so I can see where he gets his strange idea from. I suspect he is confusing emission (whether thermionic or photoelectric) with total current. In the photodiode all the electrons emitted end up at the anode. In a normal triode this is not the case. Far from being a problem, the space charge is a necessity. Not to be reduced, but encouraged.
Hi DF96
How can an electron to know if it was created by thermionic effect or by photoelectric effect?
In a photodiode NOT all electrons emited arrives to anode, after all the electron cloud/space charge isn't my invention, it exists before I was born.
I worked with Vka in te order of 4V !!!
I cosidered "secondary emission"(Anode emission), and covered the anode with black tape.
I made an anode bombardement with a LASER beam !!!
The cathode area was >> than anode area, and "secondary emission" influence was in the orther
Delta(h) = 10^-38 J s
Then I consider photon-electron interactions, same order
Delta(h) = 10^-38 J s
I cosidered everything and the electron cloud was the guilty.
How do you measure emission? I can't, I only can measure the total current.
If you think that in a photodiode all the electrons emitted ends up at the anode, It seems to me that you are confusing emission with total current.
How can an electron to know if it was created by thermionic effect or by photoelectric effect?
In a photodiode NOT all electrons emited arrives to anode, after all the electron cloud/space charge isn't my invention, it exists before I was born.
I worked with Vka in te order of 4V !!!
I cosidered "secondary emission"(Anode emission), and covered the anode with black tape.
I made an anode bombardement with a LASER beam !!!
The cathode area was >> than anode area, and "secondary emission" influence was in the orther
Delta(h) = 10^-38 J s
Then I consider photon-electron interactions, same order
Delta(h) = 10^-38 J s
I cosidered everything and the electron cloud was the guilty.
How do you measure emission? I can't, I only can measure the total current.
If you think that in a photodiode all the electrons emitted ends up at the anode, It seems to me that you are confusing emission with total current.
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With a low anode-cathode voltage (4V) a small bit of space charge will reduce current. No surprise there. Space charge reduces current in a normal valve too - that is what it is supposed to do. Photodiode operation roughly corresponds to temperature-limited thermionic valves: most, if not all, emitted electrons will go to the anode. Anode current will not vary much with anode voltage, but will vary greatly with light/heat. Once you have a substantial space charge developed (high light/heat) then current varies slowly with light/heat but quickly with anode voltage (3/2 power law).
Triode linearity does not depend on trying to do away with the 3/2 law, but ensuring that the anode and grid law are the same - then you get constant mu and low distortion. You are trying to reduce the very effect which makes valves work properly!
Triode linearity does not depend on trying to do away with the 3/2 law, but ensuring that the anode and grid law are the same - then you get constant mu and low distortion. You are trying to reduce the very effect which makes valves work properly!
Hi DF96
You still haven't understood Planck constant experiment, BTW the accepted value for Planck constant is
h = 6.626... x 10^-34 J s
Very close to the result obtained with less electron cloud/space charge !!!
I will try another approach
Lets a vacuum diode at zero total current i=0 now the thermionic effect dominates, we have only electron cloud/space charge and the current density j can be derived from Fermi-Dirac distribution, and is given by
equation (1) (Doesn't matter it's form)
For a given current density j (In the limit of large current densities) the total current i>o
Maxwell Equations=>Poisson Equation=>Child-Langmuir Law or 3/2 power law
equation (2)
For a transition from eq.(1) to eq.(2) we need increase the current. (increasing Vak par exemple)
As current increases, the electrons of the cloud are accelerated and go to the anode.
Not all electrons can escape from the cloud, increasing Vak more electrons can do it and the electron cloud effect tends to decrease as current increases.
From a given Vak, Ia vs Va graph tends to a straight-line.The 3/2 power law tends to a linear law.
Now, if we add a grid, we have a triode, and the analysis is more complex, however, for Vgk=0 the analysis done is a good approximation, and it can be extrapolated to a triode, even at Vg<0.
We must note that electron cloud/space charge ever exists, without it we haven't a valve anymore.
I hope I have explained the reason that most of us used the linear region to design a valve circuit.
Analysis is simple and crude, but can illustrate the point.
You still haven't understood Planck constant experiment, BTW the accepted value for Planck constant is
h = 6.626... x 10^-34 J s
Very close to the result obtained with less electron cloud/space charge !!!
I will try another approach
Lets a vacuum diode at zero total current i=0 now the thermionic effect dominates, we have only electron cloud/space charge and the current density j can be derived from Fermi-Dirac distribution, and is given by
equation (1) (Doesn't matter it's form)
For a given current density j (In the limit of large current densities) the total current i>o
Maxwell Equations=>Poisson Equation=>Child-Langmuir Law or 3/2 power law
equation (2)
For a transition from eq.(1) to eq.(2) we need increase the current. (increasing Vak par exemple)
As current increases, the electrons of the cloud are accelerated and go to the anode.
Not all electrons can escape from the cloud, increasing Vak more electrons can do it and the electron cloud effect tends to decrease as current increases.
From a given Vak, Ia vs Va graph tends to a straight-line.The 3/2 power law tends to a linear law.
Now, if we add a grid, we have a triode, and the analysis is more complex, however, for Vgk=0 the analysis done is a good approximation, and it can be extrapolated to a triode, even at Vg<0.
We must note that electron cloud/space charge ever exists, without it we haven't a valve anymore.
I hope I have explained the reason that most of us used the linear region to design a valve circuit.
Analysis is simple and crude, but can illustrate the point.
You still don't get it do you? If you deliberately run a valve in the region where the space charge is small then you are approaching the temperature-limited region. In this region the triode is not linear: it stops being a triode because the current depends on cathode temperature rather than electrode voltages. This is how a thermionic noise diode works.
Please go away and read up how triode valves really work. There is plenty of good stuff on the internet. I have tried to correct your misunderstanding but there is a limit to how much free tuition I can give to an obstinate student. Maybe someone else can take over. I have had enough.
Please go away and read up how triode valves really work. There is plenty of good stuff on the internet. I have tried to correct your misunderstanding but there is a limit to how much free tuition I can give to an obstinate student. Maybe someone else can take over. I have had enough.
Wasn't this the reason for g3 in a pentode and beam plates in a tetrode? Or ios this another effect?
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